DIYstompboxes.com

Hi guys,
I think you’ll find it interesting to look through the article describing IMO very interesting approach to the distortion FET stages at:
http://www.rusblues.ru/articles/tech/tech04.shtml

The article is in Russian. But I hope there is no problem to translate it somehow. Besides, the schematic language is more international than Esperanto.
Moreover, there are some opinions (including me, too) that such a circuitry is a kind of sensational and revolutionary.

Then, in turn you can find two times simpler schematic providing the same result here:
http://gtlab.net/forum/index.php?s=5492c68c71214edd5b8e5d08fbd869e2&showtopic=818

I hope some of you will continue and enrich discussion on this theme here on the Forum.

Man, that article looks pretty interesting, I wish I knew russian!

Anyway schematics and also math languaje is pretty universal, so I may be able to understand some of it

Thanks for sharing!

Miguel

if anyone can translate that, they'd sure make a hell of a lotta friends! Looks seriously interesting, damn i wish i spoke russian...

Мю-каскад на каскодных ПТ
 This one, with one fet ...<--way and the other the ---> way, I don't recall having seen before... any :idea: 's...???

8)  8)  8)  8)  8)

Quote from: petemooreМю-каскад на каскодных ПТ
 This one, with one fet ...<--way and the other the ---> way, I don't recall having seen before... any :idea: 's...???

>>>fet Darlington ?
 [fet Pinouts...ufhh..]

This is a gem! Thanks DDD!

Thanks a lot.

I love that.

Gilles C

ran website thru Babelfish several times.
replies  "error 153...try again later".
Tried it w/Netscape7 and Explorer 6.
i used "Russian to English"
Is this actually Russian, or a derrivitive?
Site looks very interesting with all those FET circuits.
LMK if anyone can get BabelFish working.
I tried Google translating, but it dosen't have Russian.
Others???
afn

OK, I just spent what seems like weeks translating the web page into techno-pidgin English on World Lingo and printing it to PDF files. Now, if I can just get somebody's permission, I'll share what I've got with everybody. Speak up - if anybody has any objections, I'll happily delete these files from my server. It's way too close to Christmas to start a flame war!  :roll:

Aron, I'd sure like your input here.

I'll take a look at it. The first site looks related to the MiniBooster.

Aron

Quote from: lovekraft0OK, I just spent what seems like weeks translating the web page into techno-pidgin English on World Lingo and printing it to PDF files. Now, if I can just get somebody's permission, I'll share what I've got with everybody. Speak up - if anybody has any objections, I'll happily delete these files from my server. It's way too close to Christmas to start a flame war!  :roll:

Aron, I'd sure like your input here.

I  would love to have an English Translation of that article,

Gilles C

i'd like a translation also.
I discovered i could paste paragraphs into BableFish
& have text come back reasonably.
Have only tranaslated about 6 paragraphs.
Bablefish must think page/text 2 large.
LoveC, have sent U a PM with my email.
thanx
tone

seems like Babelfish(altavista) and WorldLingo translate only
a limited # of characters.
BableFish says 150characters max.
WorldLingo has similar, but different, setup windows.
It translated about 6paragraphs in one click.
But, won't translate the rest.
LC,
If U've cut & pasted & cut & pasted etc etc,
U've gone thru quite a bit of effort!!!
The translation *does* come out "pigin".
That's what I was getting with Bablefish.
Notice one of the authors is "A.Distortion".
Have sent U a PM with my email.
tone

Hi, I've been trying using the online translators without much success...

Please count me in if you want to share the translation.. I could also help in reviewing the formulae and the simss.

Best regards,

STM.

Hi men,
I'm glad to see some of you got an interest to the subject.
I have to say that there are some quite sensitive points in the schematic you've seen in the article. Of course translation is very important to give you a full understanding of the schematics principle because the principle is rather new and a little bit unusual.
Without full understanding it's impossible to get proper operation of the devices. Moreover, there are some special requirements to the FETs used in the devices, e.t.c.
What about any special permission to translate the article and publish it anywhere (if I understood properly) - I'm sure that no permission is needed since the article is alreadsy published on the Net.
At the same time I've asked the author to look throuogh the present topic and to help the participants somehow. He's responsive guy I hope.

I would like to have an english translation.Or better a Dutch one :wink:
Ed

someone please translate this stuff. it looks very interesting.

OK, FWIW, here's the World Lingo version, in 4 parts and the complete figure 20 that got mangled every time I tried to print Part 4:

http://home.mindspring.com/~williamlove/Russian_dist_pt1.pdf 129K
http://home.mindspring.com/~williamlove/Russian_dist_pt2.pdf 96K
http://home.mindspring.com/~williamlove/Russian_dist_pt3.pdf 104K
http://home.mindspring.com/~williamlove/Russian_dist_pt4.pdf 403K
http://home.mindspring.com/~williamlove/Russian_fig_20.pdf   122K

It's still a machine translation, so don't expect too much - f'rinstance, the word "tube" (or "valve", if you will) translates as "lamp".  :roll:

Quote from: lovekraft0OK, FWIW, here's the World Lingo version, in 4 parts and the complete figure 20 that got mangled every time I tried to print Part 4:

http://home.mindspring.com/~williamlove/Russian_dist_pt1.pdf 129K
http://home.mindspring.com/~williamlove/Russian_dist_pt2.pdf 96K
http://home.mindspring.com/~williamlove/Russian_dist_pt3.pdf 104K
http://home.mindspring.com/~williamlove/Russian_dist_pt4.pdf 403K
http://home.mindspring.com/~williamlove/Russian_fig_20.pdf   122K

It's still a machine translation, so don't expect too much - f'rinstance, the word "tube" (or "valve", if you will) translates as "lamp".  :roll:

HA!  Is that the actual translation of the authors' names, or did you make that up?  Pretty funny!

Hey, dudes, don't laugh at our names! You'll be surprised how funny some American names sound for a Russian ear :wink:

Hey, thanks for the English translation.

Now, everything is clear... heu, almost. And I'm not talking about the translation, I'm talking about the formulas...  :oops:

Gilles

thnx for the time and effeort man... looks like an interesting read

I have to say the following on behalf of the author:
- No any permission is necessary to use his ideas or to publish them
- The subject is PAF
- Good luck!

About the author: his nickname is XBANANOV, one can find him at
http://gtlab.net/forum/index.php?showforum=2

or on the site where he publish his articles under the name "А.Дисторшен" or "Б.Овердрайв"
Regretfully his English is a little bit better than your Russian :-)

I can't really understand all the different stuff in the schematic, but as someone who grew up with all that cold war crap I think it is too cool to be talking distortion boxes with dudes in Russia.  

I also have tubes in my amp from over there somewhere.   :)

Thank you! I am sooooo glad I lost my job!!!...lol. Really! I have a new job that atarts in March which means 3 months of electronics and unemployment compensation! Apparently I'll need it for research purposes. I had the whole 3 months laid out until you through this Russian wrench in the mix. Oh well, there is never enough time anyway...for ANYTHING!!!

Thanks again!!!

DDD, could you probably check the english world lingo version for major bugs  :wink: ........besides the :idea:

you'd do us all a reeeaaaally huge favor,

markus

Thanks for the translation.  It took me about 2 hours of slow reading to understand 75% of the article.  Very thorough and informative.

Now I would like to share some thoughts:

1) Using 4 FETS, of which 2 are of one kind and 2 of another, is quite a hassle.  Moreover, the need for 2 additional FETs for the output buffer adds additional complexity.

2) I agree the results look very promising for simulating the pentode power amp saturation, but I wonder how good would a simple CD4049 / CD4069 be for this task in comparison.  These IC's are known to sound "very amp-like".  As a matter of fact, I built an overdrive with a CD4069 about two weeks ago, and was very pleased with the clipping characteristics.  This is something to further investigate perhaps with an oscilloscope, and definitely with your ears.  Also, the push-pull of P and N channel FET alternative is mentioned in the paper.  The CD40x9 falls within this category, and it is an off-the-shelf device that would need no extra matching or whatever!

3) If you want to be very purist, you can include the two-FET voltage follower after the 4-FET stage (remember the two FETS need to be of different kind).  On the other hand, if you want to keep it simple, I see no reason why you couldn't use an op-amp in voltage follower configuration.  In particular, a rail-to-rail FET op-amp like the TLC2262 should do just fine here.

4) I do not mean to diminish the interest or the author's merit in this apparently new circuit topology.  I only want to study its pros and cons carefully.  There are some very good sounding FET amp emulators, and an ALL-FET design is *very* appealing; I just want to make sure the extra effort is really going to pay-off.  Just take into account the simple tube screamer topology just rocks.

I invite you to post your comments.

STM

Day kind, expensive(dear) friends.
I the writer of this paper also can comment its some positions.
Nobody negates beauty of limitation of numeral invertors such as CD4069. But the invertors a low amplification factor, high output resistance, often have problems to conditions on a direct current owing to some asymmetry.
4FET is dispossessed first and third of the indicated deficiencies. Also gives a not less beautiful sound, than invertor.
TLC2262 It is known MOSop-amp. There is a judgement, that the common closed loop aggravates a sound. I disjoint this judgement, therefore I shall not use any op-amp whenever possible. Certainly, you can have the judgement on this problem.

Thanks for your answer, xbananoff.  I think this is a good opportunity to learn from each other and increase our understanding of FETs.

You mention some interesting points which I will reproduce here in italics (using my own words), and then my comments in normal text.

1) CD40x9 inverters have:

a. Low gain.  Yes.
b. High output resistance.  Yes.
c. Assymmetry when subject to DC loading.  Yes, as a consequence of high output resistance.

There is still a chance to use THREE inverters in series to increase gain.  I don't know if they will exhibit the soft and rounded clipping characteristic, so this needs additional testing.

Usually you use two or three inverters of an IC.  You still have several free inverters which can be used in parallel to have increased drive capability (lower output impedance).  In fact, some CD4049 designs like the Way Huge Red Llama don't use an output buffer at all.

2) The 4-FET topology has:

a. High gain.  If I understood the paper correctly, up to 3000 times?
b. High output resistance.  Hence the need for a buffer.
c. Assymmetry when subject to DC loading.   As a consequence of high output resistance.

3) Regarding OpAmp buffers you mention:

Negative effect on the audio signal due to the high gain and closed loop involved.

In this respect modern OpAmps, and especially "audio" OpAmps, are very transparent and accurate, with THD well below 0.1%.  In fact, one may dislike them due to the lack of coloration in the sound (some people may describe this as "lifeless" or "without character").

On the other hand, the proposed 2-FET buffer will certainly introduce some coloration to the sound, which may be desirable and positive to the overall sound.

4) Summary

a. I like your comments in favor of the 4-FET topolgy, and as such I think some experimentation and A/B testing with the inverters is worthwile.

b. It is also worthy to explore alternatives with CD40x9 inverters to get closer to the sound and curves obtained with the 4-FET topology due to the simplicity of inverter circuits.

Best regards,

STM

Hellow, STM
“I think this is a good opportunity to learn from each other and increase our understanding of FETs. “
I support such judgement completely!

”There is still a chance to use THREE inverters in series to increase gain. I don't know if they will exhibit the soft and rounded clipping characteristic, so this needs additional testing. “
I have conducted such trials. Each following invertor makes waveform by more square. The sound becomes more and more similar buzzness.
I am convinced, that for deriving a good sound it is necessary to try to receive major amplification in one stage. Such approach will eliminate necessity of usage of several invertors.
4FET really gives amplification in 3000 times and even more. And it only using one stage.
The amplification depends from mu used JFET.

“The 4-FET topology has assymmetry when subject to DC loading.”

We (I and You) abnormally have understood one another in a problem assymmetry.
At usage of the invertor to catch a linear condition it is complicated. And when it is possible is a major happiness. It is very similar to the equilibrist in a circus. It is possible certainly to poise an input of the invertor for this purpose. But I do not like the circuit(scheme), which one should be attuned. All should work at once.

About buffers on OPamp.
About good sound-OPamp it is known even in Siberia, where I dwell.;)
The circuits(scheme) on OPamp buffers are known for all. I would like to illustrate an opportunity to apply here JFET also.
They dye a sound low frequency harmonicses really a little. The sound in effect(result) becomes closer to a sound tube. And we you see like all a vacuum-tube sound?

4FET the circuit(scheme) is not composite. And places takes no more half-digital-chip.
I want to pay attention. 4FET gives a beautiful sound without an obtruncating of low frequencies up to the device. This indirect affirming of a small amount of intermodulation contortions of a high frequency. It is good for a sound.

Best regards

xbananoff

Welcome xbananoff! 8)

Thank you for joining with us and thank you for your great article. 8) 8)

I am eager to construct your circuits. :D

Best regards,
-Peter Snowberg



----------------------------

Big thanks also to lovekraft0 for your translation! 8) 8)

I'm glad that math and the love of distortion are universal languages. ;)

It is a pity, that in English there is't a word, which one is similar to Russian "xyeBo" (khuyovo). Such performance to the full meets to that translation. The text is transferred(translated) abnormally in many places. It hampers exact comprehension of ideas.
I wish successes in recurring those circuits(schemes).
Xbananov

Has anyone built this yet?

I would like to try it, but I don't know if it would be possible with the FETs I have.  This is what I've got:

J201
2N5457
2N5458
MPF102

I have about 10 units each, except for the J201 which I have 20, so I don't have too many to do some serious sorting/pairing.

My bet would be to use 2N5457 / 2N5458.  Of course it would be best to use 2N5457 / 2N5459, which I don't have.

Another possibility that might work is J201 / MPF102, but I don't feel like mixing two different families.

If I understood correctly, ideally you need to have the Idss in a 3:1 ratio?

Xbananoff, your comments are appreciated!

Regards,

STM

Hellow to all.

It is not necessary very carefully to select details.
This device will work after installation of any properly functioning builders.
Versions of possible substitution are reduced below.
Russin KII303A,X-->J201
KII303I' -->2N5457,2N5458

Russian KII303A and KII303I ' have a low noise and allow to receive fine result.
The application J201 and 2N5457,58 will give hardly the greater noise probably (but it will be noticeably only in a position "MIN" of a level regulator on a guitar)
In speakersim circuit:
Russian p-channel KII103 -->J2N5020
KII303X-->J201
I hope, that this information will be useful.
I wish success to all.
Xbananov

To Peter Snowberg

On this site it is interesting. Many interesting ideas and people.
Specially impress some devices operating one transistor!
To me is to that studies here.

great to see such collaboration!

welcome aboard, xbananoff!  And I'm inclined to agree about the people here being interesting (and helpful!), not to brag, of course!

You're circuits may soon be occupying bench space!

PnL,

Jeff

xbananoff,

Your english seems quite good in your posts here, would you consider making another webpage but in english?

RedHause.
The good impression about my English is bastard.

But the problems, which one preset here in a ratio of a paper, allow to make the inference about poor translation.

Natural translation to me to make complicatedly, unfortunately. The following version is possible: me send html version of that paper, translated on English, then I shall correct a little this translation to reach(achieve) the greater clearness and comprehension of a material of a paper.
Who is ready to such cooperation?

OK, I built the D90x2 circuit with J201 fets and I'm getting no sound. Are the diodes silicon or germaniums? I used 1N914's.
Jered

The circuit(scheme) does not work because of errors in assembly most likely.
it is necessary to test conditions on a direct current. On a sink T1, T6 there should be half of supply voltage, if all is collected correctly.
In D90x2 the silicon diodes utilised.

Sorry, ".. on drain T1, T6" - this is correct.

Practically a year has gone... I'm very surprised that nobody not even tried to make it. :o Ok, lets aweken your interest.
http://webdrive.purga.ru/egorov/slo/sloII11.rar (http://webdrive.purga.ru/egorov/slo/sloII11.rar)
Heh ;D

"xyeBo" (khuyovo)  thats one cool name for this project  8)
'from Russia with love' this one is ...

А по делу? Матерится мы все умеем, слава богу...  :icon_evil:

Hey, is it realy uninteresting? :o

Hi all,
Medved is surprised that nobody reports on building the subject. To be frank, the fact (if true, of course) is more than surprising.
I can say for sure that more than a half of Russian-speaking stompbox DIYers are crazy about the devices from Xbananoff (the author). Maybe, because they've built and compared the devices with the other distortion stuff?
To remind: the "heart" of the device is a cascode circuit based on couple "so-so complementary" JFETs. That gives soft clipping together with tremendous gain in a very wide dynamic range of the input signal. Moreover, such method of amplification\clipping produces very "musical" and pleasantly distorted sound. Also viirtually endless sustain and negligible noise.
At the same time the JFET buffers,  JFET speaker simulating stages e.t.c give some pleasant colour to the sound.
The sound is actually great. One can easily try it. The sound clip is in the link above.

DDD, hi! It's very pleasant for mee to see here familiar nicknames;)
And it's really, really strange that this topic which was so poular here a year ago now is called

Quote from: goosonique on November 12, 2005, 01:51:12 PM
"xyeBo"

:o  :o  :o
Ok,lets try again to awaken an interest. Here are two more samples:
http://webdrive.purga.ru/egorov/d90xgt/d90xgt1.rar (http://webdrive.purga.ru/egorov/d90xgt/d90xgt1.rar)
http://webdrive.purga.ru/egorov/d90xgt/d90xgt3.rar (http://webdrive.purga.ru/egorov/d90xgt/d90xgt3.rar)

Quote from: DDD on November 14, 2005, 12:10:05 PM
Maybe, because they've built and compared the devices with the other distortion stuff?

DDD, please, don't instigate me to begin a flame about JFETS vs All  ;D

i just noticed this because of your recent comments.  that d90x2 is one big circuit.   :icon_wink:  it might help interest if there were an english translation of the schematic.  the russian version is clear to an english reader except in a few spots.

is C1 a 1uF cap?
what do the asterisks/stars on C2, C3, C4 denote?

cheers, gm

The d90x2 schematic is rather old, but it is still rather good. Today, there are new tendences in russian  JFET schematics mostly thanks to xbananov and some more guys (me, Gunpowder, Dionis and... that's all  :( ) You can find us here http://forum.gtlab.net (http://forum.gtlab.net)
Today we have these projects:
-Bsiab mod's and unique "Bsiab Extrem" by xBananov
-Slo100 on JFET's by me
-D90x/D900 by xbananov and me
-Some variations on Orange MKII by Gunpowder.
-SpeakerSim on JFET's by xbananov
-High accuracy SpeakerSim on JFETS by Gunpowder
-Simple guitar compressor on JFETS by xbananov and Lart.

I think, that it'll be better to discuss each project in separate topic, and most common things about xbananov's circuit technique here.
As for me I  see no reason to build the distortion + spikersim in one circuit (D90x2). Individually these devices are more universal.

c1 is a 1uf cup
Star means that this cup shoud be filled in individually according to your guitar and tastes.

Quote from: Medved on November 15, 2005, 03:31:57 PM
The d90x2 schematic is rather old, but it is still rather good. Today, there are new tendences in russian  JFET schematics mostly thanks to xbananov and some more guys (me, Gunpowder, Dionis and... that's all  :( ) You can find us here http://forum.gtlab.net (http://forum.gtlab.net)
Today we have these projects:
-Bsiab mod's and unique "Bsiab Extrem" by xBananov
-Slo100 on JFET's by me
-D90x/D900 by xbananov and me
-Some variations on Orange MKII by Gunpowder.
-SpeakerSim on JFET's by xbananov
-High accuracy SpeakerSim on JFETS by Gunpowder
-Simple guitar compressor on JFETS by xbananov and Lart.

I think, that it'll be better to discuss each project in separate topic, and most common things about xbananov's circuit technique here.
As for me I  see no reason to build the distortion + spikersim in one circuit (D90x2). Individually these devices are more universal.

All the projects you mention sound really interesting, especially the BSIAB EXTREME, D90X/D and the Speaker Sim ones.  It would be great if you could post the links to the threads where the actual schematics are. I tried to navigate through the forum but it is really difficult, since it is not a matter of a different language, but also a different alphabet as well!

For instance, typing BSIAB in the search box gave me just one hit, which is a copy of your last post. Also, typing D900 gave me some hits, but couldn't get to the schematic either...

Best regards.

Heh, most of them are on our site www.gtlab.net (http://www.gtlab.net)
Ok, "Bsiab Extrem":
http://gtlab.net/gtlab2/readarticle.php?article_id=33 (http://gtlab.net/gtlab2/readarticle.php?article_id=33)
SpeakerSim on JFET's by xbananov
http://gtlab.net/gtlab2/readarticle.php?article_id=36 (http://gtlab.net/gtlab2/readarticle.php?article_id=36)
And rather old SpeakerSim by xbananov is in his famous article
High accuracy SpeakerSim on JFETS by Gunpowder:
http://gtlab.net/gtlab2/readarticle.php?article_id=31 (http://gtlab.net/gtlab2/readarticle.php?article_id=31)
About D900 you can (cannot :) ) read in russian topic which is named
"Frequency correction between cascades":
http://forum.gtlab.net/cgi-bin/yabb2/YaBB.pl?num=1118341835 (http://forum.gtlab.net/cgi-bin/yabb2/YaBB.pl?num=1118341835)
it's a link to the first page of a discussion

http://forum.gtlab.net/cgi-bin/yabb2/YaBB.pl?num=1118341835;start=all (http://forum.gtlab.net/cgi-bin/yabb2/YaBB.pl?num=1118341835;start=all)
it's a link to ALL posts in topic (>18pages), so be patient. There you can see even some clipping oscillograms of xbananov cascades.
Link to scheme of my view of D900 (which i call D90xGT)  is
http://forum.gtlab.net/yabbfiles/Attachments/Dist90xGT4.PNG (http://forum.gtlab.net/yabbfiles/Attachments/Dist90xGT4.PNG)
Samples of D90xGT are in my post on 15-11-2005, 23:47:36, sample of Slo 100 on JFET's is in my first post (12-11-2005, 20:23:50)

Hmmm. I've forgotten to tell that we have a very big time difference- 11 hours. So it's a late night in my city now. I have only 4 hours till the morning, so i'd better go to bad  ;) . See you $)

Thanks a lot.  Very interesting reading.

Babel fish does an average job in the translation, so I'm trying to fill in the gaps and missing words!

The advanced speaker simulator is very interesting, especially the "rectified" response, which is much in accordance to what you actually *hear* in comparison to the "classic" response which is more in accordance to the theoretical response in an anechoic chamber (if I understood correctly).

Regarding your D90x Ampsim, there are four schems from D90xGT1 to GT4.  I assume the numbering is chronological and increasing in quality (?) or does it have something to do with a particular model of the D900?

Best regards,

STM

Quote from: stm on November 16, 2005, 09:10:53 AM
Babel fish does an average job in the translation, so I'm trying to fill in the gaps and missing words!

Sorry, I can't understand "Babel fish". Is it a name of a translator?

QuoteThe advanced speaker simulator is very interesting, especially the "rectified" response, which is much in accordance to what you actually *hear* in comparison to the "classic" response which is more in accordance to the theoretical response in an anechoic chamber (if I understood correctly).

Hmm :) I really don't look at the classic/rectified mode from this point of view. Interesting %) As far as i know the main idea was to reproduce the amplitude-frequency characteristic of classic loudspeakers.

QuoteRegarding your D90x Ampsim, there are four schems from D90xGT1 to GT4.  I assume the numbering is chronological and increasing in quality (?) or does it have something to do with a particular model of the D900?

First of all, D90x isn't an Ampsim. It's a serious preamp like Soldano Slo-100, Bogner, Engl tube preamps. It isn't JFET schematics problems that mentioned above tube preamps cannot work from batteries and cannot be placed in a small box.  8)
Schems GT1 to GT3 were an evolution of the preamp with a clipping stage after the classical marshall tone stack. It was not a good idea. I've build it- not for my tastes. GT4 is a completed schema which sounds great.
There are two more samples, which show how D90xGT process music intervals and complex accords.
http://webdrive.purga.ru/egorov/d90xgt/d90xgt4.rar (http://webdrive.purga.ru/egorov/d90xgt/d90xgt4.rar)
http://webdrive.purga.ru/egorov/d90xgt/d90xgt5.rar (http://webdrive.purga.ru/egorov/d90xgt/d90xgt5.rar)
Only few very serious tube preamps can do something simiiar.

Quote from: Medved on November 16, 2005, 10:40:13 AM
Sorry, I can't understand "Babel fish". Is it a name of a translator?

Yes, it is an online translator capable of processing web pages as well.

Quote
Hmm :) I really don't look at the classic/rectified mode from this point of view. Interesting %) As far as i know the main idea was to reproduce the amplitude-frequency characteristic of classic loudspeakers.

You are right, after reading the translation several times I came up to understand that the term "office" (given by the translator) was refferring to the "speaker cabinet" and not to the "room" where the speaker was in.

Quote
First of all, D90x isn't an Ampsim. It's a serious preamp like Soldano Slo-100, Bogner, Engl tube preamps. It isn't JFET schematics problems that mentioned above tube preamps cannot work from batteries and cannot be placed in a small box.  8)

I see, so if you place a Magnum MkII speaker simulator after you are ready to go!

Quote
Schems GT1 to GT3 were an evolution of the preamp with a clipping stage after the classical marshall tone stack. It was not a good idea. I've build it- not for my tastes. GT4 is a completed schema which sounds great.

From what I found in the links you posted, the D900x (xbananov) and D90xGT (mod by you) preceded the GT1 to GT4 series.

Quote
There are two more samples, which show how D90xGT process music intervals and complex accords.
...
Only few very serious tube preamps can do something simiiar.

I agree, lots of clarity and sustain!

Please be aware that you have opened a can of worms, so now many questins have arised.

1) Is the LED shown in the source pins of the cascode JFETS a standard RED LED or other type?

2) I haven't been able to find information on the different diodes shown across the schematics. Consider there are at least five diode categories (apart from zeners) to consider:

a. Silicon rectifier (like 1N4001 and 1N4007)
b. Silicon signal (like 1N4148 and 1N914)
c. Shottky rectifier (like 1N5819)
d. Shottky signal (like 1N5711 and BAT45)
e. Germanium detector (like 1N34 and 1N60)

Could you please indicate the corresponding type for the following russian diodes:

KD509A
KD510A
KD521A
GD507A / 1D507A (are they the same?)

Best regards,

stm

Quote from: stm on November 16, 2005, 01:19:27 PM
I see, so if you place a Magnum MkII speaker simulator after you are ready to go!

Of course! Speakersim is very usefull thing even in a guitar head, not only in a stompbox.

QuoteFrom what I found in the links you posted, the D900x (xbananov) and D90xGT (mod by you) preceded the GT1 to GT4 series.

M... I'll try to explain... I number my schems chronologically. When i have a new idea i use a new number to publish the scheme.
The situation around this schemes is:
1) D900x (xbananov) & D90xGT - practically one thing. In GT i used bass boost in first clipping stage at it's minimum gain. That's all difference. This schems rather old.
2) GT1-GT3 is really poor choice. It was just a check-up of some ideas (mostly about tonestack and clipping stage after it). Of cource, you can build it, but result will be bad. At least I've got a bad result.
3) GT4 is the latest version of d900 at that moment. Bananov and me discussed ideas of this schema, he even made it, but didn't published the final schema. So I published my variant and named it GT4.

QuotePlease be aware that you have opened a can of worms, so now many questins have arised.

Heh, it was my goal $)

Quote1) Is the LED shown in the source pins of the cascode JFETS a standard RED LED or other type?

First of all, lets come to an agreement about terminology.
1) About JFET
Vgs- gate-source voltage
V0 - gate-source cut-off voltage
I0 - drain current when Vgs=0

2) About cascades
(http://webdrive.purga.ru/egorov/d90xgt/mucascade.gif)
It's called mu-cascade.
T1 and T2 should have equal V0
According to transistors vo diode is:
v0<1v silicon signal with voltage drop ~0.5v
1v<v0<2v IR led with voltage drop ~1v
2v<v0<3v red led with voltage drop ~1.4v
v0>3v green led with voltage drop ~1.8v
The main rule is that:
if bias on gate t2 is 4.5 then output bias should be approximatly the same (4-5v).
Instead of diode resistor with nominal of R2 can be used

(http://webdrive.purga.ru/egorov/d90xgt/cascode.gif)
It's called mu-cascade on cascode JFET's or just cascode.
T1 and T3 should have equal V0
T2 and T4 should have equal V0
V0 of T2,T4 should be 2-4 times bigger then V0 of T1,T3
Good values are 0.5-0.8v for t1,t3 and ~2v for t2,t4.
All transistors, especially t2,t4 should be with low noise!
Instead of diode resistor with nominal of R3 can be used

That's why you shouldn't install Leds in cascode! -it's the answer on your question.

KD509A,KD510A,KD521A are small signal silicon diodes.
GD507A / 1D507A are germanium diodes.

Now, you know main principles of basic schematics and we can discuss schems more deeply.

http://www.online-translator.com/srvurl.asp?lang=en (http://www.online-translator.com/srvurl.asp?lang=en)
Try to use this translator- may be it'll give better results. Or you can just compare translations.

Nice explanation ;D  Your comments are KEY to understand and design these FET circuits  :icon_idea:
Certainly we needed to establish the basics in order to be able to go deep into this.

I think there are three main causes for these FET circuits not gain so much popularity in the past here:

1) The lack of understanding of the principles behind (which you have clarified now!)  This has to do with the language barrier as well.

2) The need of different types of JFETS with well-defined parameters. This may be a barrier for those who don't have more than one type of JFET available. FETS are also not so easy to get by.  In this respect an equivalence between the russian FETS and the more familiar J201, MPF102, 2N5458, etc here might help to break this barrier.  For instance, I can see that pairs like J201 and J202, as well as 2N5457 and 2N5458/2N5459 are good candidates for the 4-FET cascode.

3) Finally, the very large number of JFETS involved in the designs may scare away many people from experimenting, especially beginners, since chances of a mistake and a circuit not working are quite high  :icon_confused:  I'm not scared at all, however I must confess I'm lazy!  :icon_redface:  Nevertheless I fell in love with the Magnum MkII speaker sim. Especially the "rectified" mode.

I have a question regarding the samples. What was the setup you used? Guitar amp/speaker sim?

I believe you have achieved a great Marshall sound.  I'm more into cleaner sounds, like a Fender amp at breakup (with a bell-like or glass-like sound) and Vox amps as well.  I would like to experiment with this FET circuits along these lines.

Thanks again, and let's keep the channels open!  I'm confident more people will jump in as we start making progress.

STM

P.D. I'll give a try to the translator you suggest. It's good to have a second opinion, however not from doctors, since you end up with two different diseases!  :icon_lol:

QuoteThe need of different types of JFETS with well-defined parameters. This may be a barrier for those who don't have more than one type of JFET available. FETS are also not so easy to get by.  In this respect an equivalence between the russian FETS and the more familiar J201, MPF102, 2N5458, etc here might help to break this barrier.  For instance, I can see that pairs like J201 and J202, as well as 2N5457 and 2N5458/2N5459 are good candidates for the 4-FET cascode.

You've forgotten a great 2sk170 :) - perfect choise for t1,t3 in cascode. It has ultra low noise... $)

Really, D90xGT has 3.5nv/vHz of input noise on 1kHz and 355nv in 70-10000 Hz. It's amazing result.
It begins to distort the output signal when input voltage is only 100-150 microvolts.

Quote3) Finally, the very large number of JFETS involved in the designs may scare away many people from experimenting, especially beginners, since chances of a mistake and a circuit not working are quite high    I'm not scared at all, however I must confess I'm lazy!    Nevertheless I fell in love with the Magnum MkII speaker sim. Especially the "rectified" mode.

You can start with only 2 jfets and one mu-cascade and get many interesting sounds. Is it so complex? :D
Pairs of fet's in each cascade in magnum speakersim should have equal I0

QuoteI have a question regarding the samples. What was the setup you used? Guitar amp/speaker sim?

Guitar->D90xGT->PowerAmp->2/3 closed back cab with 12" Celestion Classic Lead 80->Shure 565sd (analogue SM58)->Audigy.

QuoteI believe you have achieved a great Marshall sound.  I'm more into cleaner sounds, like a Fender amp at breakup (with a bell-like or glass-like sound) and Vox amps as well.  I would like to experiment with this FET circuits along these lines.

In a week or two I'm going to do a clean channel with light crunch on JFET's...

QuoteIt's good to have a second opinion, however not from doctors, since you end up with two different diseases! 

:icon_lol: :icon_lol: :icon_lol:

Quote from: Medved on November 16, 2005, 03:53:27 PM
Really, D90xGT has 3.5nv/vHz of input noise on 1kHz and 355nv in 70-10000 Hz. It's amazing result.
It begins to distort the output signal when input voltage is only 100-150 microvolts.

:icon_eek:

QuotePairs of fet's in each cascade in magnum speakersim should have equal I0

So here is where you need matching. I found the 2N5461 P-channel (available from RS Components) and I can buy locally the 2N5458 N-channel, which is its complementary pair. They both have I0(min) between 2 and 9 mA.  I think they are good candidates for the buffers on the speaker sim. Also the following couples are suitable for this, if someone can get them:  2N5460 and 2N5457 ; 2N5462 and 2N5459.

QuoteI have a question regarding the samples. What was the setup you used? Guitar amp/speaker sim?
Guitar->D90xGT->PowerAmp->2/3 closed back cab with 12" Celestion Classic Lead 80->Shure 565sd (analogue SM58)->Audigy.

So you used here the older D90xGT version? (not the GT4?)

QuoteIn a week or two I'm going to do a clean channel with light crunch on JFET's...

Great!

Regards.

While trying to digest the information given in the translated form is not that easy, is it correct to say that there are two types of cascaded FETs
One using the same type FET (J201's) and different FET's (J201 and 2N25457/8) and that the rule is that when both the same they must have matched VO or VGS and when different the FETs must meet a set Vo or VGS range so like the Phase90 the FETs must be matched.
Why do you use these different types of cascades in the shematics , are there rules for this as well.
When the ROG amp emulators hit the forum a lot was learned and some famous preamp ccts became great little stomp boxes. Can the cascade thing be taken into those designs and even further ? Im glad you have reignited the spark in this thread.

;)

Thanks
ISC

Quote from: stm on November 16, 2005, 04:48:50 PM

So here is where you need matching. I found the 2N5461 P-channel (available from RS Components) and I can buy locally the 2N5458 N-channel, which is its complementary pair. They both have I0(min) between 2 and 9 mA.  I think they are good candidates for the buffers on the speaker sim. Also the following couples are suitable for this, if someone can get them:  2N5460 and 2N5457 ; 2N5462 and 2N5459.

You can build this device using only n-channel (or p-channel as well) but in this case mathing pairs are nedeed too.

QuoteSo you used here the older D90xGT version? (not the GT4?)

No, no! GT4 of course $)

Quote from: ISC on November 16, 2005, 05:32:29 PM
While trying to digest the information given in the translated form is not that easy, is it correct to say that there are two types of cascaded FETs
One using the same type FET (J201's) and different FET's (J201 and 2N25457/8) and that the rule is that when both the same they must have matched VO or VGS and when different the FETs must meet a set Vo or VGS range so like the Phase90 the FETs must be matched.
Why do you use these different types of cascades in the shematics , are there rules for this as well.

I can't well understand you...

QuoteWhen the ROG amp emulators hit the forum a lot was learned and some famous preamp ccts became great little stomp boxes. Can the cascade thing be taken into those designs and even further ?

Yes, for example i've built Slo100 preamp on JFET's

Quote
Thanks

Not at all $)

I'll try to clarify things up (based on my current level of understanding):

Quote from: ISC on November 16, 2005, 05:32:29 PM
While trying to digest the information given in the translated form is not that easy, is it correct to say that there are two types of cascaded FETs

Don't forget to check the original article by Xbananov cited in the very first message of this post. Also, go down and you'll find four PDF files with the (automatic) translation. I suggest you print them all and contrast the original with the translation, since the translation changes some acronyms in the original making them unreadable.

Regarding JFET AMPLIFIER circuits, three different topologies have been used extensively so far:

A) Single JFET amplifier (no matching needed for obvious reasons). This kind of amplifier has been widely used for boosters and in ROG's amp sims, oh and don't forget the Fetzer Valve (by ROG) and the Marsha Valve (by Erik Vanhansen).  Clipping on the lower side is soft while clipping on the upper side is hard. IMHO this is a good representation of triodes, however the upper clipping might be too hard for some tastes. This topology has moderate gain (around 20 dB).

B) Mu-cascade (AKA Mu-amp). This uses two identical JFETs. Accurate matching is not a must, however in my sims I found that mismatch changes the upper and lower clipping level a bit, so the upper JFET biasing might need some adjustment around Vcc/2 if you desire clipping symmetry. This explains why swapping JFETs in the circuit DOES alter the sound, but IMHO, it is nothing that you can't fix with a biasing pot. This topology has been successfully used on many designs (Jack Orman introduced its use as a guitar booster), and a good example are the BSIAB I & II. Clipping is soft on both signal ends. This topology has high gain (consider around 40 dB) and it is typically associated with preamp valves. Only very light loading on the output is acceptable.

C) Quad-cascode (I introduced the term QUAD to strengthen the fact that it uses four JFETS). This is the most scary one to implement, since two different kinds of JFETs are needed. This topology can be thought of as an extension of the Mu-cascade. The important thing to remember is that the two new JFETs (T2 and T4) that go over the two original JFETs (T1 and T3) must have larger V0 (VGSoff) and I0 (Idss) in order to operate properly. The matching among the identical JFETs is desirable but not mandatory, just as in the Mu-cascade. This topology has even softer clipping, in a manner similar to the tube screamer.  It has VERY HIGH gain (consider now 60 dB) and it is associated typically with power amplifier valves. An important consideration is that this circuit needs basically no loading to properly function, so a buffer at the output is mandatory.

Now take a look at the waveforms and hopefully you'll get a better idea of what to choose:

(NOTE: image borrowed from Xbananov's article)
(http://tinypic.com/fu49y9.png)

The above was basically a rephrasing of what has been said here before and what's in Xbananov's article. Medved, please correct any inaccuracy!

Best regards,

Quote from: stm on November 17, 2005, 07:19:51 AM
Regarding JFET AMPLIFIER circuits, three different topologies have been used extensively so far:

A) Single JFET amplifier (no matching needed for obvious reasons). This kind of amplifier has been widely used for boosters and in ROG's amp sims, oh and don't forget the Fetzer Valve (by ROG) and the Marsha Valve (by Erik Vanhansen).  Clipping on the lower side is soft while clipping on the upper side is hard. IMHO this is a good representation of triodes, however the upper clipping might be too hard for some tastes. This topology has moderate gain (around 20 dB).

That's right, but! You should always remember that you have to set the working point of the scheme for each JFET individually. Isn't it maching in a sense? You should "match" resistors and JFET $)
IMHO it's bad representation of clipping triodes.

QuoteB) Mu-cascade (AKA Mu-amp). This uses two identical JFETs. Accurate matching is not a must, however in my sims I found that mismatch changes the upper and lower clipping level a bit, so the upper JFET biasing might need some adjustment around Vcc/2 if you desire clipping symmetry. This explains why swapping JFETs in the circuit DOES alter the sound, but IMHO, it is nothing that you can't fix with a biasing pot. This topology has been successfully used on many designs (Jack Orman introduced its use as a guitar booster), and a good example are the BSIAB I & II. Clipping is soft on both signal ends. This topology has high gain (consider around 40 dB) and it is typically associated with preamp valves. Only very light loading on the output is acceptable.

Jack Orman isn't an inventor of mu-cascade. At least in 1983 russian book was published with the description of mu-cascade.
Here is the first page. Pay attention to the year of publising.
http://www.sugardas.lt/~igoramps/article29/02.jpg (http://www.sugardas.lt/~igoramps/article29/02.jpg)
Here is the description of mu-cascade:
http://www.sugardas.lt/~igoramps/article29/05.jpg (http://www.sugardas.lt/~igoramps/article29/05.jpg)

You can change the level of assymetry by biasing the upper JFET- it's absolutly right, moreover, symmetric clip is often impossible when upper JFET bias is Vcc/2 even with matched JFET's. Upper clippnig level is practically Vcc, lower clipping level is gteater than voltage on the source of lower JFET which can be 1.5-2v.

QuoteC) Quad-cascode (I introduced the term QUAD to strengthen the fact that it uses four JFETS). This is the most scary one to implement, since two different kinds of JFETs are needed. This topology can be thought of as an extension of the Mu-cascade. The important thing to remember is that the two new JFETs (T2 and T4) that go over the two original JFETs (T1 and T3) must have larger V0 (VGSoff) and I0 (Idss) in order to operate properly. The matching among the identical JFETs is desirable but not mandatory, just as in the Mu-cascade. This topology has even softer clipping, in a manner similar to the tube screamer.  It has VERY HIGH gain (consider now 60 dB) and it is associated typically with power amplifier valves. An important consideration is that this circuit needs basically no loading to properly function, so a buffer at the output is mandatory.

No, it isn't an extension of the mu-cascade. It is exactly a mu-cascade but on complex JFET's. It's a big difference. Gain can be as high as 70-75db. It's also very sensitive to input capacity of the buffer.

Here is a new sample of D90xGT4 which contains only acoustic feedback of amp and guitar. I think it's interesting... Singinig guitar... $)
http://webdrive.purga.ru/egorov/d90xgt/d90xgt6.rar (http://webdrive.purga.ru/egorov/d90xgt/d90xgt6.rar)

Quote from: Medved on November 17, 2005, 09:57:43 AM
That's right, but! You should always remember that you have to set the working point of the scheme for each JFET individually. Isn't it maching in a sense? You should "match" resistors and JFET $)
IMHO it's bad representation of clipping triodes.

Maybe, but it is well known that triodes clip in an assymetrical way, and I don't see this represented by the mu-cascade or the quad-cascode.  :icon_question:

QuoteJack Orman isn't an inventor of mu-cascade. At least in 1983 russian book was published with the description of mu-cascade.
Here is the first page. Pay attention to the year of publising.
http://www.sugardas.lt/~igoramps/article29/02.jpg (http://www.sugardas.lt/~igoramps/article29/02.jpg)
Here is the description of mu-cascade:
http://www.sugardas.lt/~igoramps/article29/05.jpg (http://www.sugardas.lt/~igoramps/article29/05.jpg)

We are aware of this, this subject has been discussed before. My point in mentioning Jack Orman is that he was (AFAIK) the first guy that reported using that circuit topology to amplify a guitar signal, not meaning he invented it.  I've also seen that circuit in a National Semiconductor Application Handbook which I happen to have at home. I'm not sure of the printing date, but it was during the 80's.

Quote
You can change the level of assymetry by biasing the upper JFET- it's absolutly right, moreover, symmetric clip is often impossible when upper JFET bias is Vcc/2 even with matched JFET's. Upper clippnig level is practically Vcc, lower clipping level is gteater than voltage on the source of lower JFET which can be 1.5-2v.

In my sims I found also that changing the Source resistors on the two JFETs (with values between 100 and 1k) you can achieve this as well.

QuoteNo, it isn't an extension of the mu-cascade. It is exactly a mu-cascade but on complex JFET's. It's a big difference. Gain can be as high as 70-75db. It's also very sensitive to input capacity of the buffer.

This circuit I haven't been able to simulate it properly. I am using 2N5457 and 2N5459 JFET SPICE models provided by Microcap 7, but I only get HARD clipping, much harder than with the mu-cascade  :icon_question:  If you have made succesful simulations, could you post the SPICE models used on both kinds of JFETs?

Best regards.

Quote from: Medved on November 16, 2005, 02:47:08 PM

Quote
First of all, lets come to an agreement about terminology.

2) About cascades
(http://webdrive.purga.ru/egorov/d90xgt/mucascade.gif)
It's called mu-cascade.

(http://webdrive.purga.ru/egorov/d90xgt/cascode.gif)
It's called mu-cascade on cascode JFET's or just cascode.

?

Puretube, I simulated the two circuits above, with the only difference being that I replaced the diodes with 2k resistors.
I also played around with the values of these resistors, making them as low as 100R.

First I started simulating with a single FET amplifier and got the expected waveform shown above (waveform A).

Then, tried the mu-cascade and got the same waveforms I reposted above (waveform B).

Finally, the 4-FET cascode produced much harder clipping instead of the soft curves previously posted (waveform C). I started with V0=-1V for T1 and T3, and V0=-3V for T2 and T4. I also moved these values arounds, but could not reproduce the waveforms. I started with the 2N5457 and 2N5459 SPICE models supplied by the sim SW, and then adjusted V0 (VGSoff) accordingly.  If you invert the positions of the 2N5457 and 2N5459 the circuit won't amplify, which is expected.

I also tried bypassing the lower 2k resistor (diode in the schematic) with a 100uF capacitor, and also with smaller resistors up to zero ohms. I wonder if someone has been able to obtain these waveforms in a simulation or only observed them with an oscilloscope.

sorry for the disturbance,
but my questionmark was related to the images (pics)
that appeared when I looked 2 pages back,
while I had 2 of the russian sites open in other windows...
(those 2 pictures showed changing fotos,
of teddybears and of showering ladies...  :icon_redface:)

I had strange appearances/experiences before, with east-european sites earlier,
but those pics really didn`t fit into this forum!

Must be a funny provider, to show wrong pics,
while looking at "properties", it said to be the relevant
(mu-cascade) pix...

QuoteMaybe, but it is well known that triodes clip in an assymetrical way, and I don't see this represented by the mu-cascade or the quad-cascode.

Heh, 3 JFET cascades are also exists $) (see "Bsiab Extrem" for example) You can use a 2/3..3/4 (1/3..1/4) of vcc to bias the upper JFET- there are many ways to get asyymetrical clipping if needed.

QuoteMy point in mentioning Jack Orman is that he was (AFAIK) the first guy that reported using that circuit topology to amplify a guitar signal, not meaning he invented it.

The discription of the schema begins with words:
"On pic.72 is the scheme of a distortion box on two JFET's..." And so on.
AFAIK- as far as i know... Now you know further  :D  :D  :D
Ok, it isn't really so important today who was the first ;)

QuoteThis circuit I haven't been able to simulate it properly. I am using 2N5457 and 2N5459 JFET SPICE models provided by Microcap 7, but I only get HARD clipping, much harder than with the mu-cascade    If you have made succesful simulations, could you post the SPICE models used on both kinds of JFETs?

Try to use 2N4117 and 2N3819 models in simulator if you have ones. Later i can post models of russian JFET's made by xBananov himself.

Quote from: puretube on November 17, 2005, 12:56:38 PM
Must be a funny provider, to show wrong pics,
while looking at "properties", it said to be the relevant
(mu-cascade) pix...

The ftp server which i use seems to have such bug- once it showed me strange images which clearly belonged to somebody else...

QuoteJack Orman isn't an inventor of mu-cascade. At least in 1983 russian book was published with the description of mu-cascade.

Jack Orman has never claimed to have invented the mu-amp and has always been straight forward in listing the original source for this basic building block...   the National Semiconductor AN-32 applications note that is dated February 1970, or 13 years before your Russian source.

Get your facts straight.

regards, Jack Orman

Quote from: stmI wonder if someone has been able to obtain these waveforms in a simulation or only observed them with an oscilloscope.

I got waveform results similar to that shown above in Circuitmaker 6(student) with the schematic as-is, using the 2N5457 model for T1 and T3, the 2N4416 model for T2 and T4, and a +/-100mV 1KHz sine input, if that's any help to anybody.
(http://home.mindspring.com/~williamlove/waveform.png)

Quote from: lovekraft0 on November 18, 2005, 12:09:53 AM
I got waveform results similar to that shown above in Circuitmaker 6(student) with the schematic as-is, using the 2N5457 model for T1 and T3, the 2N4416 model for T2 and T4, and a +/-100mV 1KHz sine input, if that's any help to anybody.

Thanks, using the models you suggested I got similar results. I checked this circuit has a gain around 65 dB, while a mu-cascade with two J201's give 38 dB in my sim. This is in accordance with the GAINS.

What I cannot get to match is that my mu-cascade amplifier has softer clipping characteristics in comparison to the quad-cascode. I expected the opposite based on the graphs posted before by Xbananov, and reposted by me some replys above.

I was working with an input level of 100mV. I then reduced level to 10mV and the mu-cascade went into the linear region, while the quad-cascode was still clipping, now even harder than before.

The following image shows the waveforms for 100mV input, J201/2N4416 for the quad cascode with two 2k resistors on the sources, and J201 on the mu-cascade with 1 ohm resistors on the sources.

(http://tinypic.com/fuucrb.png)

The quad-cascode has definitely more gain, however the mu-cascade has softer clipping.

Quote from: amz-fx on November 17, 2005, 07:43:16 PM

QuoteJack Orman isn't an inventor of mu-cascade. At least in 1983 russian book was published with the description of mu-cascade.

Jack Orman has never claimed to have invented the mu-amp and has always been straight forward in listing the original source for this basic building block...   the National Semiconductor AN-32 applications note that is dated February 1970, or 13 years before your Russian source.

A key word in my phrase is at least. I just said what i knew. I didn't claim that it was invented in Russia $) Nevertheless in this book mu-cascade was used as a distortion cascade for a guitar.

stm, lovekraft0
Guys, slow down a bit!
Some comments from bananov:

Quote from: stmSo here is where you need matching. I found the 2N5461 P-channel (available from RS Components) and I can buy locally the 2N5458 N-channel, which is its complementary pair. They both have I0(min) between 2 and 9 mA.  I think they are good candidates for the buffers on the speaker sim. Also the following couples are suitable for this, if someone can get them:  2N5460 and 2N5457 ; 2N5462 and 2N5459.

Place at least 0.5k resistor in sources or you'll ruin yourself on bying batteries :)

QuoteThe important thing to remember is that the two new JFETs (T2 and T4) that go over the two original JFETs (T1 and T3) must have larger V0 (VGSoff) and I0 (Idss) in order to operate properly. The matching among the identical JFETs is desirable but not mandatory, just as in the Mu-cascade.

Matching among the identical JFETs is not needed at all- you should make shure that t1 has vo in 0.7-1v, t3 vo is less than 1v, t3,t4 vo in 1.8-3v.

Now about sims. Simulators have VERY poor mathematical model of JFET. They practically don't show the dependence of JFET's mu from VDS and different drain currents. That's why images of clipping are far from real, espessialy of 4FET cascode as modelling errors because of incorrect dependence of mu from vds and Id are multiplying instead of summing in mu cascsde.

And second. Please, don't forget that 4fet cascode has 10times more gain than mu-cascade! Pictures in xBananovs article was given for an input voltage nearly 10 times the voltage of clip beginning of each cascade. All voltages are different! For 4fet cascod it shold be nearly 10-20mv... And cascode shuold be real not virtual... Then you'll see what you want:)

Heh, again no answers...
Ok, I wrote sounds of mucascade and cascode cliipping of 1k wave with variety of input signal's level. It's ~7Mb rar archive and i can't upload it to ftp- i have modem.
Here is only two sounds:
http://webdrive.reborn.ru/egorov/d90xgt/Clip.rar (http://webdrive.reborn.ru/egorov/d90xgt/Clip.rar)
Anyone can open them in sound editor and see real clipping images:) Nothing similar to sims...

And as I promissed I public the scheme of clean channel on jfets:
(http://webdrive.reborn.ru/egorov/clean/Clean2.PNG)
Here is a sample on max gain:
http://webdrive.reborn.ru/egorov/clean/Clean1.rar (http://webdrive.reborn.ru/egorov/clean/Clean1.rar)

Some comments:
KP303G- any lownoise JFET with cutoff voltage near 2V
KP301A~J201
First mucascade starts to clip nearly at 1v input amplitude. It's sensivity is set by R3 and it shouldn't clip while normal playing. I use a mucascade in a first stage for ability to use a booster- clipping will be soft and pleasant. I use linear gain pot. With audio pot "clean" is up to 85-90% and only then overdrive begins- it isn't very convenient.

Thanks for sharing.

What's your setup for recording?

Setup is the same:
Guitar yamaha rgx-112-->Clean channel-->Power amp tda7294-->Cabinet 1*12 2/3 closed back--> Mic Shure 565sd -->Audigy

First of all, you should try supply voltage near 25V with adjusting R3 and maybe R11. I have only 15V, but it's sounds very good. Soon, i'm going to add a tremolo %)

Hi Medved,

Thanks for sharing your work and experimentation here with us. Your exploration of some rarely-used circuits for amplifying guitar is commenable and valued by many of us who share your interest in this area.

Medved said

QuoteNow about sims. Simulators have VERY poor mathematical model of JFET. They practically don't show the dependence of JFET's mu from VDS and different drain currents. That's why images of clipping are far from real, espessialy of 4FET cascode as modelling errors because of incorrect dependence of mu from vds and Id are multiplying instead of summing in mu cascsde.

Well-said!

Spice is good for designing filters under linear operating conditions, and for designing circuits using a few specialized chips that have good models, but most Spice models of JFETs (and most other linear) devices are so oversimplified that their modeling of device behavior under clipping conditions fails miserably to model their behavior with any accuracy.

Thanks for reminding us all of this as well !

More breadboarding and less computer simulations - yeah!  :icon_mrgreen:

Quote from: Medved on December 16, 2005, 04:21:16 PM
Setup is the same:
Guitar yamaha rgx-112-->Clean channel-->Power amp tda7294-->Cabinet 1*12 2/3 closed back--> Mic Shure 565sd -->Audigy

First of all, you should try supply voltage near 25V with adjusting R3 and maybe R11. I have only 15V, but it's sounds very good. Soon, i'm going to add a tremolo %)

Nice sound considering you are using a SS Power amp, which as I understand, it has basically flat frequency response and negligible THD.

It is important to notice the higher voltage requirement. For a typical pedal this circuit could be implemented with two 9V batteries, for a total of 18V.  I did some experimentation last weekend with the Fetzer Valve, Marsha Valve and MuAmp (using 9V), but wasn't very satifsied with the sound when they started clipping.  Gotta try with higher voltage and use the MuAmps instead of single FETs.  In fact I got better results with the experiments I did with a CD4049 in respect to low OD levels for "clean" guitar playing.

Bad sign for this COOL international exchange - all the links on

http://webdrive.purga.ru/egorov/

went dead.  :(

Let's hope Medved just changed servers...

The clean channel sounds a lot like the old single tube preamp Alembic used to make... Mainly the sound of the tone controls. Sounds better just before it starts distorting audibly. I suppose it is just clipping the transient peaks, but my oscilliscope is on the bench to fix this month :(

Anybody else playing with the quad cascode these days? It does have some interesting sonic properties if you play around with various JFETs and circuit values.

Hey folks,

Just switch the web addrress to

http://webdrive.reborn.ru/egorov/

and Medved is back on line.  ;D

Anyone working on the translation business further (trying to clean up the machine translation and symbols to match the USA versions) ?

Hi, guys!
Sorry, i was busy with my learning...
First of all more sounds:
D90:
http://webdrive.reborn.ru/egorov/d90xgt/d90xgt7.rar (http://webdrive.reborn.ru/egorov/d90xgt/d90xgt7.rar)
http://webdrive.reborn.ru/egorov/d90xgt/d90xgt8.rar (http://webdrive.reborn.ru/egorov/d90xgt/d90xgt8.rar)
http://webdrive.reborn.ru/egorov/d90xgt/d90xgt9.rar (http://webdrive.reborn.ru/egorov/d90xgt/d90xgt9.rar)
And my favorite:
http://webdrive.reborn.ru/egorov/d90xgt/d90xgt10.rar (http://webdrive.reborn.ru/egorov/d90xgt/d90xgt10.rar)
Clean:
http://webdrive.reborn.ru/egorov/clean/Clean2.rar (http://webdrive.reborn.ru/egorov/clean/Clean2.rar)
http://webdrive.reborn.ru/egorov/clean/Clean3.rar (http://webdrive.reborn.ru/egorov/clean/Clean3.rar)
http://webdrive.reborn.ru/egorov/clean/Clean4.rar (http://webdrive.reborn.ru/egorov/clean/Clean4.rar)
Here is my Fender DG-22CE:
http://webdrive.reborn.ru/egorov/clean/Clean5.rar (http://webdrive.reborn.ru/egorov/clean/Clean5.rar)
http://webdrive.reborn.ru/egorov/clean/Clean6.rar (http://webdrive.reborn.ru/egorov/clean/Clean6.rar)

QuoteJust switch the web addrress to http://webdrive.reborn.ru/egorov/ and Medved is back on line.

Yes, absolutely right

QuoteIt is important to notice the higher voltage requirement. For a typical pedal this circuit could be implemented with two 9V batteries, for a total of 18V.

Yes, for pedal 18v is the best solution. I didn't try to use 25v... There could be some problems... 9v is to low for my clean scheme. If you want to use 9v you should change first cascade to follower.

Guys, if you want a quick response, write me directly on my mail : nospamtomson@bk.ru. Without nospam of course...

http://webdrive.reborn.ru/egorov/d90xgt/d90xgt11.rar (http://webdrive.reborn.ru/egorov/d90xgt/d90xgt11.rar)
In style of Napalm Death. Tunning in B...

Wecome back!!

Thanks.

Nice sound. Is the schematic link dead? I'd love to breadboard this circuit.

hi medved,

i've seen lots of versions of the d90x series. the latest seems to use a lot of complementary push-pull stages. how good does the matching have to be? this seems to be a drawback of using these.

Quote from: theman on February 05, 2006, 01:09:25 AM
i've seen lots of versions of the d90x series. the latest seems to use a lot of complementary push-pull stages. how good does the matching have to be? this seems to be a drawback of using these.

Complementary push-pull stages are just buffers. I can redraw scheme without it.

yes, if you could, please post your latest design schematic using buffers which are not push-pull. what do you recommend (jfet source follower with another jfet as a current source?).

Ok.
http://webdrive.reborn.ru/egorov/d90xgt/Dist90xGT_b.PNG
It's moderately high gain (clipping begins from 0.5-1m of input signal). All trannies are nJFET.
KP303A<-->low noise, V0~-0.6-0.8v, I0~1ma (j201, but it is more noisy then KP303A)
KP303G<-->low noise, V0~-2v, I0~6..10ma or so (2n3819 maybe... but i can't say anything about it's noise...bf245b seems to go... Again i don't know about it's noise...)
Sound:
http://webdrive.reborn.ru/egorov/d90xgt/d90xgt12.rar

thanks!

btw, how do you change the design and get clips out so fast? is the design on a proto-board or breadboard?

Quote from: theman on February 06, 2006, 05:17:32 PM
btw, how do you change the design and get clips out so fast? is the design on a proto-board or breadboard?

Yes.

Some minor changes were maid in last scheme dist90x_b.png, so check it out...
About diods. D1 is any led with 1-1.5v drop (With kp303g (v0=-2v) i use 1v drop infrared led)
D2 is any germanium diod, D3- silicon. You can try any other type of diodes and choose one you like best.

Here is sound in linein and processed one with impulse of 2*12 cab.
http://webdrive.reborn.ru/egorov/d90xgt/Line1.rar
Some comments. Max.gain (more than max.gain of bognerTG by two or three times!) sounds rather pleasant in linein: clear attack, good lows, moderate hiss, accords are well readable...

are the minor changes you mention just the diode changes you talked about in your last post?

No. Some capacitors, etc... Soon, i'll publish more or less finished one...

Ok. Some more changes were maid in dist90x_b.png. Now it's good.

Technical characteristics:
Supply voltage: 9..24v
Quiescent current: 5-6ma
For Russian JFET's input voltage noise at 1kHz: 3.5nv/vHz.
Gain up to 90dB at 1k. With 15 supply it starts clipping at 0.5-0.6mv double amplitude input voltage.

KP303A<-->low noise, V0~-0.6..-0.8v, I0~1ma.
KP303G<-->low noise, V0~-1.8..-2.5v, I0~6..10ma or so.
D1 is any led with 1-1.5v drop.
D2 is any germanium diod.
D3, D4- silicon.

J1,J2 should have equal V0.
J5,J6 should have equal V0.
J7,J7 should have equal V0.
J4 should have I0 5-15% bigger than I0 of J3.
J9 should have I0 5-15% bigger than I0 of J10.
J12 should have I0 5-15% bigger than I0 of J11.

thanks for the new info. please post the new schematic when you are finished. regarding the I0 differences ... these are for the same type of transistor. will the design work if the transistors do not meet the "5-15% bigger" requirement?  also -- would like to understand the advantages and disadvantages of the buffers you use. the push-pull complementary seem to be good, but might need matching as opposed to the JFET source follower with a jfet current source. which is preferred? do you hear sonic differences?

Quote from: theman on February 12, 2006, 07:57:42 AM
thanks for the new info. please post the new schematic when you are finished.

New scheme is in old place. So, download it again.

Quote from: theman on February 12, 2006, 07:57:42 AM
regarding the I0 differences ... these are for the same type of transistor. will the design work if the transistors do not meet the "5-15% bigger" requirement?

From 6 JFETs you'll find 3 pairs. Belive me :)
It will work only if upper JFET has bigger I0. If its I0 is much bigger, than buffer can clip signal. Anyway, just check the output bias- if it's less than 100-200mv then it's ok.

Quote from: theman on February 12, 2006, 07:57:42 AM
also -- would like to understand the advantages and disadvantages of the buffers you use. the push-pull complementary seem to be good, but might need matching as opposed to the JFET source follower with a jfet current source. which is preferred? do you hear sonic differences?

Complimentary buffers have smaller output impedance, a bit (1..2db) less noise and soft clipping.
But in this case it is no difference between buffers at all.

hi medved,

is it possible to use a different jfet for the upper jfet in the buffers ... something like a J202 or Russian KP303I?  these have higher i0. also, i'd like to ask what effect does the gain pot and feedback network have?  is there a way to get rid of the gain pot? the current design already has 6 knobs!  :(

thanks for all the feedback on this cool design ...

theman

Hi. By the way, where are you from? What Russian JFETs can you buy?
If you use high I0 upper jfet in buffer then output potential will be much highier than input one. It can be 2-3v higher- such buffer will clip upper half-wave.
Gain pot changes gain :)
When gain is max, lows and highs are reduced, when gain is min amplitude-frequency response is flat.
It adds one more degree of freedom in sound. I think that it's better to use 2 pots tonestack than removing gain pot. Nevertheless, it can be easily removed.

i'm in california, usa. i don't have access to any russian jfets -- just have read that the KP303I is close to a J202. thanks for your suggestions. your gain pot sounds like a presence or contour knob -- not really affecting gain, but changing the frequency response of the circuit. for example, you said when gain is max, highs and lows are reduced -- does this produce a mid-boost or hump? for many, this is desireable. 

i agree with you on keeping this knob -- it is a pre-gain EQ in a sense, which is needed in many super-high-gain circuits for proper tonal shaping. any thoughts on comments on what's the best post-gain two-knob tonestack to use?  the vox/hotbox tonestack seems to be a lot different tonally than the marshall you are using ...

Quote from: theman on February 12, 2006, 09:59:01 PM
i'm in california, usa. i don't have access to any russian jfets -- just have read that the KP303I is close to a J202. thanks for your suggestions. your gain pot sounds like a presence or contour knob -- not really affecting gain, but changing the frequency response of the circuit. for example, you said when gain is max, highs and lows are reduced -- does this produce a mid-boost or hump? for many, this is desireable. 

No, it's not a contour or presence knob. It affects gain. Max gain of first stage is about 30-32dB, minimum- nearly 12-14db. What's the difference between mid-boost and hump? It's only your choice how much lows and highes are reduced...

Quote from: theman on February 12, 2006, 09:59:01 PM
i agree with you on keeping this knob -- it is a pre-gain EQ in a sense, which is needed in many super-high-gain circuits for proper tonal shaping. any thoughts on comments on what's the best post-gain two-knob tonestack to use?  the vox/hotbox tonestack seems to be a lot different tonally than the marshall you are using ...

The tonestack of xbananov... You can find it on his bsiab mod. I've posted a link...

can you explain what the gain knob does to the tone? at min gain, do you still get a high-gain tone (if drive is cranked), and how does it compare to the tone when the gain is maxed? is there any filtering going on at all?  i thought that the feedback path from the output to the gate of the upper jfet is a high-pass filter.

Quote from: theman on February 15, 2006, 04:42:01 PM
can you explain what the gain knob does to the tone? at min gain, do you still get a high-gain tone (if drive is cranked), and how does it compare to the tone when the gain is maxed?

At min gain it is just an overdrive. And sounds like overdrive. At max gain... You have heard how it sounds at max gain.
At min gain and low drive it has clean sound with light crunch...
Ok, i'll write you some sounds soon.

Quote from: theman on February 15, 2006, 04:42:01 PM
is there any filtering going on at all?  i thought that the feedback path from the output to the gate of the upper jfet is a high-pass filter.

At min gain no filtering is perfomed, at high gain lows and highes are reduced. In mucascade feedback is positive, that's why low and high pass filters in feedback path boost mids by reducing lows and highs.

I've bought american strat $)
Here are some samples of clean channel from all strat's pickups:
http://webdrive.reborn.ru/egorov/Clean/StratB_r.rar
http://webdrive.reborn.ru/egorov/Clean/StratB+M_r.rar
http://webdrive.reborn.ru/egorov/Clean/StratM_r.rar
http://webdrive.reborn.ru/egorov/Clean/StratM+N_r.rar
http://webdrive.reborn.ru/egorov/Clean/StratN_r.rar

A sample of very new distortion design:
http://webdrive.reborn.ru/egorov/Bogner/bog_fet3.rar
(611kb)

Hi
would somebody post a current schematic of this effect?
thanks

I'd like to take a peak at this too!

There are some problems with tunning- it's only a sample device. I can show the scheme, but without oscilloscope it's hard to make it working in proper way.

This 3d is VERY interesting !!  :icon_idea:
Thank you boys  ;)

Antonello

Sample of another device (practically full copy of DualRecto) with same clipping stages:
http://webdrive.reborn.ru/egorov/Slo/SloIII_1r.rar
(663 kb)

Scheme:
http://webdrive.reborn.ru/egorov/Slo/slo.PNG
Please, don't try to build it, if you have no oscilloscope. I can't help you to tune the scheme in this case.

Could you make the drain resistors as trim pots and get it to work more easily? The architecture looks similar to many 4 stage tube preamps -- just different inter-stage filtering and attenuation -- which I believe contribute a lot to the character of the distortion. The Dr. Boogey and Cauldron of Gain (similar to Bogner XTC) are some examples. They also use a Marshall-style tonestack at the end, driven by a follower.

QuoteCould you make the drain resistors as trim pots and get it to work more easily?

Without osci or precise math - no. I can't explain it to you, because of my poor English. :(

QuoteThe architecture looks similar to many 4 stage tube preamps -- just different inter-stage filtering and attenuation -- which I believe contribute a lot to the character of the distortion. The Dr. Boogey and Cauldron of Gain (similar to Bogner XTC) are some examples. They also use a Marshall-style tonestack at the end, driven by a follower.

The interstage filtering is exact copy of Slo100/DualRecto. The main difference from Dr.Boogey and others is clipping stages. J2 and J4 clipping is practically identical copy of tube stage clipping.

http://webdrive.reborn.ru/egorov/Bogner/bog_fet4r.rar
(1.02M)
One more sample.

oh my god..this pedal is simply awesome!!!will someone post a layout or a pcb for this wonderful effect?

Be patient, we are working on maths...

Hi Medved, I gained a lot of understanding with respect to the operation of FET equations during the development of the Fetzer Valve article (http://www.runoffgroove.com/fetzervalve.html (http://www.runoffgroove.com/fetzervalve.html)).  I offer you my help with the math and the preparation of the text in english.

Also, regarding the schem, are the D9b diodes typical signal diodes or are they germanium or power diodes?

D9b are germanium. Schottky are also usable (1n5917, etc).
About math. Let's do this way: you'll try to calculate the shown stage yourself (stage+load). We (xbananov (the author of a stage) and I ) have different points of view on calculations. 3 methods are better than 2, aren't they? :)
I'll try to explain you the basic concept. The main idea is not to allow the stage to clip hard the lower half-wave of stage output.
And, please, do calculations of source resistors with given drain resistor, not inverse...

Medved, PM sent.

stm, i've sent an e-mail, but there is no answer.
http://webdrive.reborn.ru/egorov/Bogner/comp.rar
(272kb)
One sample is tube BognerTG Sharp channel, another- FET preamp.
Any assumptions? :)

Medved, I'm afraid I didn't get your message.  Most likely the spam filter took it away.

I developed a couple of equations for the simplified circuit with one Drain and one Source resistors.  I can calculate the source resistor (Rs) for a given FET (Vp, Idss) with a given supply voltage (Vcc), with a give drain resistor (Rd) and a given biasing drain voltage (Vd).  The formula is not simple, as it includes a squareroot.  This assumes the source resistor (Rs) is bypassed by a large capacitor.

I also derived a formula to predict gain in the above condition, which again is rather cumbersome.  I have them at home, so let me know if you want me to post them.

Cheers.

Did anyone try to build this actually?

I have access to 2n5484 2n5486, but those have quite high cutoff voltage ... 1.1- 1.3V (5484) and 3.7-4.5V (5486). Could I try with these or should I try to get access for some J20x:s.

Hell yeah!!!!!!!!!

Let's get this thread back on track.

STM - did you and xyeBo ever get the collaboration going?

mr coffee

another vote for thread re-opening !!

i think it's time for a new generation of F4T :-)

First of all, guys, let's forget the word "xyeBo" since the word is pretty bad, OK?

Agreed. Very interested in reading this.

AFAIK the "brains" behind those russian FET distortions are currently working for AMT Electronics (also russian). As a result now you have FET pedals such as M-1, P-1, F-1, R-1 etc. which means they would be somewhat reluctant to share more than what is already available. There are also some interesting ideas about emulating  FETs with opamps but most links to schematics are dead now.

Here is something similiar and Google translates it into English for me.
All of these designs are very excellent ,dead ringers to my ears, of the original amps they emulate.
http://www.guitarjfet.ru/index.php?option=com_content&task=view&id=30&Itemid=34

I would get those schematics while they are still there.
I have wanted to try some of them all year but just too busy.
I listened to the sound samples when I first found this and they all sounded excellent.

I found the above link here at DIYSB somewhere originally if IIRC.

This one too,this guy's stuff is awesome very realistic sounding FET emulations and cab sims. http://milas.spb.ru/~kmg/index_en.html

This is a similiar page with scope shots.It also translates with Google.
http://www.sugardas.lt/~igoramps/article68/article.htm

This will help with your cross referencing of part numbers. http://matthieu.benoit.free.fr/cross/russian_equiv.htm

As will this one: http://www.ok1rr.com/e107_plugins/content/content.php?content.28

Here is more related FET stuff: http://www.radiomuseum.org/forum/the_trioderizer_a_solid_state_triode.html

http://www.diystompboxes.com/smfforum/index.php?topic=70065.80

http://home3.netcarrier.com/~lxh2/

The sugardas site just explained how a circuit works that I'm making right now. Gonna go board it shortly and get it finalized and drawn up. Uses J201's.

Thanks for the links. Just motivated me!

The top link above has a Mesa boogie sim that's not a doctor boogie may be worth boarding up although some of the transistors look like there models I haven't seen before?

Cool ideas! But these guys need to hire a translator...or we should learn russian. I can't follow all they say as i do with the fetzer valve article.  :icon_sad:

(http://i852.photobucket.com/albums/ab86/pigyboy_2009/FETpreamplayout.png)
This is from the page Brymus posted the link to above. What are the V's with 4 pins? ???

                     Possibly dual-gate mosfets - the only thing I've seen with 4 pins in a metal case . Worth a shot.

Glad I could help create interest in these FET emulations.
Hopefully some will be verified and layouts drawn up for the forum at some point.

I did accouple Eagle layouts of some of these schematics. I never made any, I was just tyring to learn how to use Eagle. If anyone wants them let me know. I can not say they are the best designs.

Quote from: caspercody on October 23, 2010, 09:24:32 PM
I did accouple Eagle layouts of some of these schematics. I never made any, I was just tyring to learn how to use Eagle. If anyone wants them let me know. I can not say they are the best designs.

Put them up please. It is another place to start. Can you post the eagle files too so we can use what you have already done?
Thanks
Chris

Nice to hear there is people who like this article too. I've been reading these victor kempf /xbananov articles for few weeks now. I have become an big fan of his works.

Specially i am amazed of this 4fet high-gain cascode thingy. I just havent found an sound sample if this four fet cascode thing, which would be nic :icon_biggrin:e to heart. Getting those even harmonics with solidstate, ü

For me google chrome does the job for translating from rus-eng . Its not perfect, but readable...

I hope to get some lab.time soon to start with protos.

VICTORTION is my idea if a petname  :icon_biggrin:

I have nver figured out how to attach files on this forum. If you send me a PM with your email address, I can send them to you.

Quote from: nick d on October 23, 2010, 07:06:29 PM
                    Possibly dual-gate mosfets - the only thing I've seen with 4 pins in a metal case . Worth a shot.

Nope, the 4th V's (КП303...) leg (actually it is th 1st from the mark cw) is ground contact, reduces noise. КП303 are n-channel Jfets, not mosfets. :icon_wink:

By the by, I use BF512 FETs instead of the Russian КП303В successfully.
BF512 are very good FETs, low-noise and tolerant to static electricity, etc, etc.

Does anyone still have copies of the 4 fet schematics ?

This all sounds so interesting but the links are dead