The "SANSVALVE" :
(http://img.photobucket.com/albums/v437/latronax/sansvalve2138.jpg)
Actually, RP & RL can be omitted, and be replaced by a bare wire (link)
block schematic here... (http://img.photobucket.com/albums/v437/latronax/sansvalve2136.jpg)
inspired by a post from gez in brett`s other thread (http://www.diystompboxes.com/smfforum/index.php?topic=59106.msg463393#msg463393).
good as is as a standalone "grinder" for humbucker type guitars.
Modifications coming up...
:icon_cool:
Did you match the transistors? If not, whereabouts do the input/output bias up at?
Ton, almost forgot to mention. You can take the signals at the sources and feed them to diodes to create an octave up effect (works the same as a phase splitter). You might need to increase the value of the source resistors to do this though: I did this with 4007s a few years ago and I think I had to use quite high value resistors to get a decent signal voltage across them. The beauty of this is that you can still take the signal from the 'normal' output. There should be some info in the archives.
ahh - there you are :icon_smile:
no matching - just grabbed the first ones out of 2 bags...
automatic exactly 4,5V (4V5)/(4.5V) biasing!
and that`s what stumped me, too:
no datasheet or schoolbook description has been able to explain to me why this actually happens...
(is it, like in this case, that I apparently happened to grab 2 matching P / N devices with nearly identical UGS/ID,
and that they just by accident are balancing?).
Quote from: gez on July 18, 2007, 05:17:14 PM
Ton, almost forgot to mention. You can take the signals ...
HUSH! :icon_wink: :icon_wink:
Modifications:
1.) "stone"-mod: shortcircuit (= insert a link instead of) RS.
2.) "metal"-mod: shortcircuit (= insert a link instead of) RD.
3.) "wood"-mod: shortcircuit (= insert a link instead of) RS & RD.
1.) & 2.) will produce "dirtier", louder, less compressed distortion (asymmetric),
while 1.) is treblier and less aggressive than 2.).
3.) will be softer (almost symmetric) and more dynamic than the basic version and than 1.) & 2.)...
2.) is noisier than 1.)... ("hiss")
(gez: 1.) & 2.) do severely unbalance the DC offset at the output: 6.5V / 2.5V respectively, instead of 4.5V...)
haven`t measured the current consumption of mod 3.)...
ps:
" RP " & " RL " are the protective and/or current limiting resistors,
inspired by cmos-inverter datasheets,
but of no influence, soundwise...
" RM " can be shortcircuited (linked), but otherwise defines a certain minimum "drive" (gain-factor),
which can go from <1 to ~80 times... (the latter for small input volumes up to ~25mV)*
*anything louder than that, will be squashed/distorted at higher drive/gain settings**
** signals lower than ~250mV can be boosted clearly by a factor of <1 to >10.
Max. output signal voltage (@ 100k load) is ~ 4Vpp; (~6Vpp for mods 1.) & 2.)...
Thanks for posting this, I'll have to break out the bread board later and take a look.
I played with something almost similar for the Mosfet FX-X. I didn't get it done in time though so I ended up with what I entered. Noticed my entry had BS170s and BS250s ? Left overs from playing a similar idea. ;) I'm glad someone got something in that vain out.
Thanks! :)
Andrew
ooops - hadn`t noticed...
came up with this coz I didn`t have non-SMD inverters at hand to quickly view what happens with brett`s "deadshort"
in the other thread... (thanx, gez!),
and I really wanted to know (but still don`t...).
(the "deadshort" secret probably lies in the fact, that it is being (DC-coupled...) biased to half-supply by the previous stage...)
http://www.diystompboxes.com/smfforum/index.php?topic=59106.0
please note, that Brett`s R8 is a " RD " for all stages simultaneously,
coz it`s not de-coupled at pins 1/8... :icon_wink: :icon_wink: :icon_wink:
Quote from: puretube on July 18, 2007, 07:11:14 PM
ooops - hadn`t noticed...
I did try to create something similar to enter but ran out of time. Instead I turned the Mosfet pair into an one shot timer for a noise maker called Forsaken.
Andrew
Looks good that. I've been thinking about this since the comments on the other thread. I'm wondering did you try plugging some random samples in to see if it always biases half way? I don't have any P mosfets to try it out. I have a feeling a similar thing can be done with jfets with different biasing. Does it sound good with a guitar through it?
I forget where I read about this but, one of the "older" electronics manuals referred to this as a "totem-pole".
Wish I could remember where I saw it though. Now I feel older than I did a minute ago..... :icon_rolleyes:
Geez...now I've gotta build this one.... :icon_evil: :D
Looks cool PT...as usual !
I tried simulating it. It has a gain of 600 before it clips. The input impedance looks about 1.5k. Is that right or what? That's without the 100k gain control.
Quote from: puretube on July 18, 2007, 05:37:32 PM
haven`t measured the current consumption of mod 3.)...
What happens (sound wise) if you use source bypass caps?
PS Have you seen the new 'members only' area? :icon_wink:
gez: initially, I did the Rd/Rs bridging with caps...
but when I found those mosfets so perfectly matching,
I wanted to save parts...
This morning I did some random mixing of several BS170 (from 3 different manufacturers (dunno, which)),
with several BS250 (from one batch):
they all stayed within 150mV of Ub/2!
However the 3 bs170s from one manufacturer sounded harsher with either bs250,
2 from an other sounded "different",
while 10 other bs170s from one batch all were "cool" (=warm) sounding and at the exact same bias.
So: manufacturer does matter in sound!
(btw: I have not tried other P- or N-MosFets than the 170/250s!)
Since I noticed the "harsher" ones got quite hot with Rd/Rs shorted by wires,
I now again prefer the bridging with 10µ caps, especially with unknown transistor types.
(although this doesn`t sound as saturated and smooth, when driven hard...)
When done with caps, you probably can omit the safety resistor Rl safely.
Jaytee: simulations are one thing... :icon_rolleyes:
I measured ~80mV out for 1mV in, @ open as well as with 4M7 feedbackresistor,
with the "gain"-pot at zero.
With the sound I hear coming out of this, I don`t care about the input impedance :icon_biggrin:
ps: oh yes - the circuit accepts/welcomes integrating ("de-hissing") caps from out-to-in like all those other integrated
multilegged tempered halfused hexcircuits... :icon_mrgreen:
Quote from: puretube on July 19, 2007, 05:03:40 AM
This morning I did some random mixing of several BS170 (from 3 different manufacturers (dunno, which)),
with several BS250 (from one batch):
they all stayed within 150mV of Ub/2!
Wow, that's really interesting. I wonder why (seems counter-intuitive)?
Nice to know that if the 4000 series ever goes the way of the dinosaurs there's an alternative. We'll just need to power these circuits from the mains in the future... :icon_lol:
from mains to headphones? :icon_eek:
btw:
noticed another thing:
similar to not liking zero Ohm between out & in,
they don`t like to be DC-coupled in cascade: so better use caps between consequent stages... :icon_wink:
oh, yes: "piggybacking": forget it... (zero improvement)
I tried random pairs of fets (simulation) and they all balanced up. It would be interesting to see what happens with a buffer in front of it. If the input impedance is so low you might not be getting full gain. The standing current might be quite high because theres 4.5v bias on the gate. A lower supply voltage or bigger source resistors would reduce it.
Quote from: jaytee on July 19, 2007, 08:49:30 AM
The standing current might be quite high because theres 4.5v bias on the gate. A lower supply voltage or bigger source resistors would reduce it.
Good point! Removing the source resistors and running things at 5V might improve the current consumption (yet retain the softness resulting from the exclusion of these resistors).
I wonder how a power stage would fair? I tried this last year, but (assuming that the power inverter wouldn't bias at half supply) I incorporated a servo circuit to do the job. End result was oscillation that I just couldn't get rid of. Had I known they balance up nicely, I wouldn't have bothered with the servo! :icon_rolleyes:
only done this with those smallsignal babies - dunno how the powerdevices would behave (???)
So as not to show off the usual schoolbook curves/waves of the common smooth clipping,
instead I got a nice experiment with 2 of them discrete inverters + 1 cap & 1 resistor:
creeping frequency "dubbler" (http://www.youtube.com/watch?v=AOxVo-9BM60)
(looks like someone writes the initials "m m" onto the screen... :icon_lol:
blending frequency "multi plyer" (http://www.youtube.com/watch?v=aLgmxghNUUg)
(both envelope-dependant: no knobs moved during recording).
The clips don`t sound as seary as it comes out of the speakers, due to the microphone pointing towards the damped ceiling...
Quote from: gez on July 19, 2007, 06:59:31 AM
Quote from: puretube on July 19, 2007, 05:03:40 AM
This morning I did some random mixing of several BS170 (from 3 different manufacturers (dunno, which)),
with several BS250 (from one batch):
they all stayed within 150mV of Ub/2!
Wow, that's really interesting. I wonder why (seems counter-intuitive)?
Hmmm... I don't really know anything about mosfets, but could the nice bias be related to the same effects that cause the soft clipping?
This is what got me thinking about it (quote from the other thread):
Quote from: gez on July 17, 2007, 07:56:34 PM
Transconductance of each device drops off when pushed into saturation, hence the compression.
So if the transconductance is a smooth curve where transconductance goes down when SD-voltage goes down, this kind of symmetrical circuit probably will seek an operating point whre they balance or something...
I'm not too sure I understood this stuff at all... Just quessing.
I like!
Andrew
Petri: I had posted some nice basic FET links in an old thread (http://www.diystompboxes.com/smfforum/index.php?topic=29414.msg245542#msg245542),
(see also reply#24, there)
which I had deleted a while later after having been annoyed/molested by the usual gang, for whom I thought
it wasn`t worth pointing to at that time...
I dug them out again for explanations in some other recent threads (http://www.diystompboxes.com/smfforum/index.php?topic=59303.msg463000).
they`re interesting, but don`t reveal all questions:
FET principles & circuits pt.1 (http://www.nutsvolts.com/~downloads/fetmay.pdf),
pt.2 (http://www.nutsvolts.com/~downloads/fetjun.pdf),
pt.3 (http://www.nutsvolts.com/~downloads/fetjul.pdf),
pt.4 (http://www.nutsvolts.com/~downloads/fetaug.pdf), by the great Ray Marston.
Quote from: The Tone God on July 19, 2007, 02:24:09 PM
I like!
Andrew
I wonder, whether the MO or the PM-Club is the better place to disclose the schematic for the
Waveply,
or if I just ought to wait to submit it for the monthly contest (being a neg-FB-circuit)...
Quote from: puretube on July 19, 2007, 04:18:20 PM
they`re interesting, but don`t reveal all questions:
Cool stuff! Thank you! I did not read it all yet but sooner or later I will. Even if they don't answer everything, they seem to be just the kind of basic info that is relatively easy to use when experimenting.
Got to try this mosfet circuit too when I get some other things out of the way... Your sounclips sounded very cool.
Quote from: puretube on July 19, 2007, 04:24:37 PM
I wonder, whether the MO or the PM-Club is the better place to disclose the schematic for the Waveply,
or if I just ought to wait to submit it for the monthly contest (being a neg-FB-circuit)...
Its your design so the choice is yours. :)
Andrew
Quote from: jaytee on July 19, 2007, 08:49:30 AM
The standing current might be quite high because theres 4.5v bias on the gate.
I'm beginning to think that this is the reason why everything biases at half supply. As there
is so much voltage on the gate, both channels are conducting nicely. If manufacturers produce devices that have consistent Rds when in such a state, it would make sense that a discrete inverter would bias around half supply.
Edit: bias is one thing, but how a pair behave as an amplifier is another matter: I should think that 'unmatched' devices would produce a little asymmetry. Ton, out with the scope again! :icon_lol:
no need to... :icon_biggrin:
the different sounding ("different"/"harsher") fets of various manufacturers that I mentioned in reply#16 (http://www.diystompboxes.com/smfforum/index.php?topic=59383.msg463960#msg463960),
were indeed accompanied with deviations from an otherwise ("cool"=warm) symmetrical waveform.
The "good" ones:,
(http://img.photobucket.com/albums/v437/latronax/MosFets02158.jpg)
which stayed closer @ Ub/2 than the mentioned ~150mV deviating ones
happened to be from the same distributor, but obviously not from the same manufacturer...
concerning: a day out with the scope, again :icon_lol:
I tried to capture the frequency tripling (http://www.youtube.com/watch?v=qy2NV4nu8zY) on the "WAVEPLY" vid,
but the cam wouldn`t wanna focus sharply... (but with a little imagination you can see 2cuts descending from the top of the wave,
cutting it into 3).
another setting gives a larger multiple of peaks (3-7 or8) (http://www.youtube.com/watch?v=KsYJM3XpIJ4),
again not to be seen very well,
but maybe better heard here (http://www.youtube.com/watch?v=x9-lWqIYQ1g),
where for the first 10 seconds the guitar volume was rolled down, then turned on to full volume...
Petri: more food... (http://www.geofex.com/Article_Folders/mosboost/mosboost.htm) from R.G., this time.
Without the (admittedly) dirty "add 1 resistor + 1 capacitor"-trick,
that made a "WAVEPLY"
out of a dual (cascaded) "SANSVALVE"
the following pic shows, that a "cleaner" ordinary frequency-tripleing
(as is well known from other circuits...)
can also being achieved, by using a less mean trick,
to bring forth the: "TRIFOLD":
(http://img.photobucket.com/albums/v437/latronax/trifold2160.jpg)
(now the sun doesn`t shine onto the tube anymore, the image became clearer...).
It`s obvious to be seen, how during (the imposed) one cycle of the input sine
which shows one "peak" up and one "peak" down,
the derived wave shows 3 peaks up and 3 peaks down.
:icon_smile:
referring back to the sansvalve, you can get some asymmetry by putting a resistor "inside the inverter". for example, between the drain of the PMOS and the "out" junction. sort of a joe davisson kind of idea. :icon_wink:
[oops. editted "resistor" back into the post.]
Quote from: gaussmarkov on July 20, 2007, 02:08:17 PM
referring back to the sansvalve, you can get some asymmetry by putting a resistor "inside the inverter". for example, between the drain of the PMOS and the "out" junction. sort of a joe davisson kind of idea. :icon_wink:
[oops. editted "resistor" back into the post.]
I posted a circuit that has that very implementation a few years ago. It's hosted by Marcos. I think I called it the Nut Cruncher.
Quote from: puretube on July 20, 2007, 06:25:21 AM
the following pic shows, that a "cleaner" ordinary frequency-tripleing
(as is well known from other circuits...)
Hey, keep out of my waveforms! ;)
Andrew
Quote from: gez on July 20, 2007, 02:57:43 PM
Quote from: gaussmarkov on July 20, 2007, 02:08:17 PM
referring back to the sansvalve, you can get some asymmetry by putting a resistor "inside the inverter". for example, between the drain of the PMOS and the "out" junction. sort of a joe davisson kind of idea. :icon_wink:
[oops. editted "resistor" back into the post.]
I posted a circuit that has that very implementation a few years ago. It's hosted by Marcos. I think I called it the Nut Cruncher.
:icon_biggrin: and exactly (not "sort of") a gez kind of idea! thanks gez. :icon_cool:
for those who are search-challenged: gez's nut cruncher (http://www.geocities.com/diygescorp/nutcruncher.gif) at Munky DIY (http://www.geocities.com/diygescorp/)
Quote from: The Tone God on July 20, 2007, 03:19:41 PM
Quote from: puretube on July 20, 2007, 06:25:21 AM
the following pic shows, that a "cleaner" ordinary frequency-tripleing
(as is well known from other circuits...)
Hey, keep out of my waveforms! ;)
Andrew
:icon_razz:
I`m doing an initials-collection:
in reply#21 it was the "MM"
a little while ago I had a very nice "Z"-sign :icon_wink:
and recently, a quite realistic looking (fastood-)"M" logo... :icon_mrgreen:
does the sansvalve need matched MOSFETs? i see that gez used a CD4007 for his nut cruncher and that gives nicely matched pairs. but given that asymmetry introduced by a resistor is interesting, it seems possible that "odd couples" might be a good thing too.
ton, you just grabbed a pair out of the pile for your experiments, right?
Quote from: gez on July 19, 2007, 08:55:16 AM
Quote from: jaytee on July 19, 2007, 08:49:30 AM
The standing current might be quite high because theres 4.5v bias on the gate. A lower supply voltage or bigger source resistors would reduce it.
Good point! Removing the source resistors and running things at 5V might improve the current consumption (yet retain the softness resulting from the exclusion of these resistors).
I wonder how a power stage would fair? I tried this last year, but (assuming that the power inverter wouldn't bias at half supply) I incorporated a servo circuit to do the job. End result was oscillation that I just couldn't get rid of. Had I known they balance up nicely, I wouldn't have bothered with the servo! :icon_rolleyes:
Wait!:
4.5V bias?
isn`t the bias: V
GS?
the "R
S" & "R
D" inserted between the sources and the rails
reduce the voltage between the rails
and the sources (in the sansvalve case by ~2 - 2.5V, with the 1k "inline"-resistors),
so there`s only 2 - 2.5V left for "bias"...
Quote from: gaussmarkov on July 20, 2007, 05:20:03 PM
does the sansvalve need matched MOSFETs? i see that gez used a CD4007 for his nut cruncher and that gives nicely matched pairs. but given that asymmetry introduced by a resistor is interesting, it seems possible that "odd couples" might be a good thing too.
ton, you just grabbed a pair out of the pile for your experiments, right?
yep, the "Nutcruncher" doesn`t count here, because it`s not discrete :icon_eek: ( :icon_smile:);
upon jaytee`s request in reply#10, I tried a lot of combinations of all (~30) mosfets of the named types (170/250) I had at hand,
as noted in reply #16.
The (small) variations in the established bias
was audible and visible,
but close enough to be acceptable for the usual circuits, and especially for a "trimmerless-field-effect-stage"
(that very first breadboard test was a completely "blind" test, but perfect).
Gotta keep in mind, though, that it`ll always be a "classA/B" configuration, with a potential for crossoverdistortion ( :icon_wink: :icon_wink:).
Back to your question:
it obviously doesn`t need matched components (for the types used), and no adjustments.
(which is the fact I loved about the hex-inverters, and always thought is immanent only to
them...).
It seems that the manufacturers are able to produce tight V
t tolerances in these devices nowadays;
and the use of those "inline"-resistors, that increase ("linearize") the resistance of the voltage-divider (Rds
P/Rds
N)
which in fact establishes the bias fromout its center-node, seems to add to the symmetry (me thinks)...
Quote from: puretube on July 20, 2007, 05:24:25 PM
Wait!:
4.5V bias?
isn`t the bias: VGS?
the "RS" & "RD" inserted between the sources and the rails reduce the voltage between the rails
and the sources (in the sansvalve case by ~2 - 2.5V, with the 1k "inline"-resistors),
so there`s only 2 - 2.5V left for "bias"...
Yeah, I had accounted for that. Even with the reduced voltage (can't remember off-hand, but isn't typical threshold of BS170 about 1.8V??) both channels should be conducting nicely (though not fully on).
looks like somebody ( :icon_question:) needs to hook up 3 ampere- and 4 volt-meters plus scope and amp to the circuit,
and make up a datasheet... :icon_eek:
(gez: former post is add-on edited...)
I tried a single stage this afternoon and it biased up just as you said it would (trebles all round)!
I used a couple of medium power MOSFETs that can take up to an amp of drain current; all run from a 12V supply. Have only tested it with my function generator and scope so far. With source bypass caps the signal goes straight into hard clipping. However, once removed I got the soft clipping you normally associate with inverter ICs. This pretty much backs up my findings from the last time I investigated all this.
Although the chips - they're little 4pin DIL MOSFETs - I used can source a fair bit of current, gain was killed with a heavy load (even with the bypass caps) due to the output being taken from the drains: impedance is too high. I'll stick a little audio transformer on the end tomorrow and see if I can get the circuit to drive headphones.
Quote from: puretube on July 20, 2007, 05:16:27 AM
Petri: more food... (http://www.geofex.com/Article_Folders/mosboost/mosboost.htm) from R.G., this time.
Oh... Somehow I have missed that even though I have read much stuff from geofex during the last 5 years (or maybe 10 years). Thanks again. I think I will print these all as I need some reading for a holiday trip I'm going.
That 4007 chip seems handy for this... I wonder how it sounds compared to separate discrere mosfets...
Does anybody have any recordings of this circuit with bass guitar please?
Thanks for the inspiration Ton!
(http://hometown.aol.co.uk/Gezpaton/Kink+Tank.gif)
For a one stage circuit, it's not bad: like an amp just on the verge of breaking up. My scope seemed to suggest some limiting of highs and this was confirmed when I plugged a guitar in (slightly muffled sound, but nothing too dull and it meant there was no need for a tone stack). Probably gate capacitance; I'll have to check the data sheets.
welcome, gez! :icon_cool:
(did you try a second "boostchannel", or "fuzz" with one or both Rs switchably bypassed?)
(yes, I know it pops while switching...)
couldn`t get my hands off the basic circuit myself,
and, inspired by a comment in another post (reply#38) (http://www.diystompboxes.com/smfforum/index.php?topic=59383.msg464555#msg464555)
I came up with the: "CSPWMB" *:
(http://img.photobucket.com/albums/v437/latronax/CSPWMB02164.jpg)
(block schemo)
the sounds of which in turn inspired me towards a new song...
*: "Can`t Stop Playing With My Baby"
:icon_smile:
Quote from: puretube on July 20, 2007, 05:16:32 PM
Quote from: The Tone God on July 20, 2007, 03:19:41 PM
Quote from: puretube on July 20, 2007, 06:25:21 AMthe following pic shows, that a "cleaner" ordinary frequency-tripleing(as is well known from other circuits...)
Hey, keep out of my waveforms! ;)
Andrew
:icon_razz:
I`m doing an initials-collection:
in reply#21 it was the "MM"
a little while ago I had a very nice "Z"-sign :icon_wink:
and recently, a quite realistic looking (fastood-)"M" logo... :icon_mrgreen:
Today`s special is the "VW" initials:
(http://img.photobucket.com/albums/v437/latronax/VW-logo2161.jpg)
it was drawn with the follow-up circuit of the aforementioned "CSPWMB" (http://www.diystompboxes.com/smfforum/index.php?topic=59383.msg464987#msg464987),
whose inspiring reedy, raspy, and brassy as well as its cut-membrane and mis-biassed-amp sounds has lead
to another modification, the:
"WORN-SECTION".
To me it sounds
that terrific, that even Sir Stephen would let it slip through the fuzz-box barrier... :icon_wink:
Messed around a little with headphones this morning. I know from previous experiments with CMOS headphone amps that you need to treat them like Class A amps and get the drain current right up. Using 15 ohm source resistors (with suitable power rating) I got about 120mA. Slightly short of what I calculated would be needed to drive 320mW 32 ohm phones (both cans in parallel), but it worked. The chips ran hot, but according to the supplier's calatogue they can take 1A and don't require heatsinks.
As a headphone amp it sounded better than a stand-alone effect, and was a lot of fun (almost like having a tube amp in your cans: clean, but with a little breakup here and there). Not exactly efficient, but less hassle than a toob.
Gez: did you use a "hard" power supply, or rather the "saggy" type?
btw:
the comment mentioned in reply#45 (http://www.diystompboxes.com/smfforum/index.php?topic=59383.msg464987#msg464987)
was about the fact that these inverters are class AB devices...
trying to exploit some possibilities concerning crossover distortion, I thought about swapping the "inline"-resistors from the sources to the drains, for the "CSPWMB", but with no result;
Instead, I then put some resistors in series with the drains additionally to the circuit with the "source"-resitors...
to try out all possibilities, I substituted these resistors with a pot (P2), whose wiper constitutes the new output,
and parallelled another pot (P1), in order to be able to blend out the effect of the drainresistors altogether:
(http://img.photobucket.com/albums/v437/latronax/overcrosser2168.jpg)
(both 100k, but 50k or 25k will do, too, depending a bit on the sourceresistors values...)
Playing a bit more with the "Worn-Section" (http://www.diystompboxes.com/smfforum/index.php?topic=59383.msg464994#msg464994), it was able to create an even less sharp "TriFold" (http://www.diystompboxes.com/smfforum/index.php?topic=59383.msg464317#msg464317) than in the "WavePly":
(http://img.photobucket.com/albums/v437/latronax/tripler2166.jpg)
(@ ~25mV input amplitude)
but the most fascinating effect is the phasey changing interaction of the harmonix,
when the louder signal gradually descends from the "Fivefold":
(http://img.photobucket.com/albums/v437/latronax/fipler2167.jpg)
(@ ~100mV input)
down through above trifold to the single fundamental, as it decays...
:icon_cool: :icon_cool: :icon_cool:
Quote from: puretube on July 23, 2007, 12:46:02 PM
but the most fascinating effect is the phasey changing interaction of the harmonix,
when the louder signal gradually descends from the "Fivefold":
down through above trifold to the single fundamental, as it decays...
Now I am again going to have to ask you to step away from my waveforms.
Andrew
P.S. A forth coming design does something similar.
You ain`t heard nothing yet...
ps: I`m not aware of your waveforms... :icon_confused: :icon_frown: :icon_question:
:icon_wink:
Quote from: puretube on July 23, 2007, 01:18:03 PM
ps: I`m not aware of your waveforms... :icon_confused: :icon_frown: :icon_question:
The tripling is something
Finish Line does and a newer version goes into this phenomena further hence me bugging you to "keep out of my waveforms". :)
Andrew
Quote from: puretube on July 23, 2007, 12:18:40 PM
Gez: did you use a "hard" power supply, or rather the "saggy" type?
Hard/stiff: variable-voltage, regulated power brick (running things off 12V).
Interesting that you're experimenting with drain resistors. I'm wondering if this isn't a better way to go in reducing current as the inclusion of source resistors generates a little distortion of its own. An alternative would be to bias the gates either side of the centre point and leave out all source resistors. I'll do a little testing after I've finished experimenting with the headphone amp.
I haven't had a chance to get any MOSFETs yet - can anybody tell me how this circuit sounds with Bass guitar, please?
Or better yet, does anyone have any samples or Youtube videos of the above, please?
Thanks,
Alex
Quote from: The Tone God on July 23, 2007, 01:36:13 PM
Quote from: puretube on July 23, 2007, 01:18:03 PM
ps: I`m not aware of your waveforms... :icon_confused: :icon_frown: :icon_question:
The tripling is something Finish Line does and a newer version goes into this phenomena further hence me bugging you to "keep out of my waveforms". :)
Andrew
Sorry, I didn`t wanna anticipate future circuits/waveforms of yours... :icon_smile:
(arrgh - and I was so proud of the linear+exponential sawtooth (http://www.youtube.com/watch?v=-E0_UW-qD3k) generation of the "Worn-Section" with that sharp little dent at the bottom, during attack...)
(maybe this then is the right thread to note that I happily delivered some of my more advanced IC-based "dancing harmonics" tri-and-more-folders to a safe place, during MusikMesse Frankfurt (http://img.photobucket.com/albums/v437/latronax/hidden%20pix/DIRTY015.jpg), in April 2005) :icon_surprised:
hopefully, the following 2 waveform movies don`t interfere with anyone`s plans:
The 2 "OverCrosser" (http://www.diystompboxes.com/smfforum/index.php?topic=59383.msg465245#msg465245) pots described for the "CSPWMB" work as follows:
P1 controls the amount (percentage) of crossover-distortion, and can vary the waveform horizontally (http://www.youtube.com/watch?v=e4yfG_JVbHk), when rotated,
while
P2 controls the position of the crossover point in the waveform vertically (http://www.youtube.com/watch?v=3LdyQzOD7fI), when rotated.
another one for Isaiah, who may have missed the other clips hidden in this thread... :
"Devolution" (http://www.youtube.com/watch?v=RG9JxsOfVmc) shows the decay from multiple (sharp sounding) peaks to more or less pure sinewave, when the signal gets weaker (from the "Waveply").
(haven`t tried bass, yet).
Quote from: puretube on July 24, 2007, 11:03:06 AM
The 2 "OverCrosser" (http://www.diystompboxes.com/smfforum/index.php?topic=59383.msg465245#msg465245) pots described for the "CSPWMB" work as follows:
P1 controls the amount (percentage) of crossover-distortion, and can vary the waveform horizontally (http://www.youtube.com/watch?v=e4yfG_JVbHk), when rotated,
while
P2 controls the position of the crossover point in the waveform vertically (http://www.youtube.com/watch?v=3LdyQzOD7fI), when rotated.
And I answer with Blade (http://www.diystompboxes.com/smfforum/index.php?topic=51877.msg390996#msg390996). ;)
But now that I bring that up I got some new ideas. :icon_twisted:
Andrew
Quote from: puretube on July 24, 2007, 11:03:06 AM
hopefully, the following 2 waveform movies don`t interfere with anyone`s plans:
The 2 "OverCrosser" (http://www.diystompboxes.com/smfforum/index.php?topic=59383.msg465245#msg465245) pots described for the "CSPWMB" work as follows:
P1 controls the amount (percentage) of crossover-distortion, and can vary the waveform horizontally (http://www.youtube.com/watch?v=e4yfG_JVbHk), when rotated,
while
P2 controls the position of the crossover point in the waveform vertically (http://www.youtube.com/watch?v=3LdyQzOD7fI), when rotated.
That's clever! I didn't understand the schematic at first but it finally clicked. :icon_cool:
I've been experimenting a little too. The Kink Tank works well as a headphone amp from a 12V supply, 15 ohm source resistors (bypassed) and a larger drive pot (the thing was too loud). With headphones loading the output, clipping was soft with a test signal. In the real world, the distortion (when it kicks in) has a slight rattle too it, which I'm not that keen on. The sound is reminiscent of 4007 circuits, which never sound as smooth as 4049 circuits IMO. Not bad, just different. For a while now I've wondered whether the n and p devices in the 4007 aren't as well matched as in 4049 circuits. The scope images I'm getting with discrete MOSFETs are similar to those I've got with 4007 chips. Who knows...
I tried biasing both MOSFETs either side of the centre point. There comes a point where drain current drops dramatically. The further away from the centre the gates are biased, the more the mismatch between thresholds becomes apparent: the outputs no longer bias up nicely and the 'symmetry' pot ends up being used as a 'bias' pot to get things to sit in the middle again. I wonder if my earlier comments about Ron being more consistent at higher drain currents is the reason?
Dear My Tone God:
in order to get out of Your waveform-territory,
I implemented a change of topology concerning the output-circuitry of the "Worn-Section"...
(while the complete rest of the circuit stays absolutely the same, ie.: 2 cascaded "SanseValves". );
according to the saying:
"as well as every input can be used as an output, every output can be used as an input"
(or at least something similar to that has been said by a wise (wo-)man a while ago...) :icon_confused: :icon_question:,
out comes a blendable (rotating the blend-knob*) from "clean" (well, err..., cmos-distorted fundamental)
saw-wave, to twice the frequency,
(without the transitional wave-folding going on in those other aforementioned circuits):
http://www.youtube.com/watch?v=hmyplRWeYXM
actually, the clip starts with a spaced sawtooth @ the middle of the blend knob`s rotation,
turning to the (distorted) fundamental at ccw, then rotating cw for full duplex (=octave up),
and back and forth, again.
Yes, I owe You and Gez 2 extra-schemo details by now...
(PM-club...)
btw: the manual blending can be done remotely (in a followup circuit...) by expression-pedal, or dual VCA.
Thank YOU!
BTW I was kidding about playing around with "my" waveforms but it did get me back to thinking about a few different things which I will play with later. Right now I have to work on my FX-X entry for this month which I have yet to start. :icon_rolleyes:
Thanks again for the videos and circuits. :)
Andrew
Quote from: The Tone God on July 24, 2007, 01:28:33 PM
Quote from: puretube on July 24, 2007, 11:03:06 AM
The 2 "OverCrosser" (http://www.diystompboxes.com/smfforum/index.php?topic=59383.msg465245#msg465245) pots described for the "CSPWMB" work as follows:
P1 controls the amount (percentage) of crossover-distortion, and can vary the waveform horizontally (http://www.youtube.com/watch?v=e4yfG_JVbHk), when rotated,
while
P2 controls the position of the crossover point in the waveform vertically (http://www.youtube.com/watch?v=3LdyQzOD7fI), when rotated.
And I answer with Blade (http://www.diystompboxes.com/smfforum/index.php?topic=51877.msg390996#msg390996). ;)
But now that I bring that up I got some new ideas. :icon_twisted:
Andrew
that`s what this thread is for... :icon_smile:
(bringing up new ideas)
BTW: the "OverCrosser" (http://www.diystompboxes.com/smfforum/index.php?topic=59383.msg465245#msg465245)-mod does it
crackle-free. :icon_wink:
Had a little time this morning to do some more testing. By biasing both gates slightly off-centre, I was able to reduce/control current in the inverter and remove the source resistors. However, transconductance was too high and clipping was harsh (no subtle compression as the output nears the rails). Pity, as the source resistors definitely contribute towards distortion of the wave form and, after a little testing, I think I know what's going on.
Due to negative feedback, neither the n or p device acts as a follower. Instead, each source resistor forms a divider with the channel of its respective device. The effective resistance of each device's channel changes with the voltage on the gates. Considering (for convenience) the n-channel's source only, the source will drop as the output drops. However, with negative swings on the gates (positive output swings) the n-channel narrows, its effective resistance increases and it pushes the (comparatively small) source resistor down. End result is full-wave rectification, albeit around a shifting DC centre-point. The latter is partly due to inverters making poor amplifiers. The virtual-earth effect isn't perfect so a tiny voltage is seen at each source (it acts as a slight follower). When either the p or n device are pushed into saturation, negative feedback is lost and a slight voltage builds up on the gates, in turn increasing the slight 'follower signal' seen at the source.
Unfortunately, all of the above causes slight distortion to the peaks of the signals. Perhaps this accounts for the slight 'rattle' I mentioned? Bypassing the source resistors cures the problem but creates another: transconductance is too high and clipping is hard (again, there is no soft compression as the output approaches the rails).
Looks like drain resistors might be the way to go (for me)...
Quote from: puretube on July 19, 2007, 04:24:37 PM
Quote from: The Tone God on July 19, 2007, 02:24:09 PM
I like!
Andrew
I wonder, whether the MO or the PM-Club is the better place to disclose the schematic for the Waveply,
or if I just ought to wait to submit it for the monthly contest (being a neg-FB-circuit)...
Well, on second and third thought, it not neccessarily being a neg. FB circuit, but rather some kind of to-and-fro-feed
of those tiny signal-dirt remnants that Gez mentioned above on the "southern" sources,
why not show the block-schemo here:
(http://img.photobucket.com/albums/v437/latronax/WavePly2165.jpg)
and the full one there... (http://img.photobucket.com/albums/v437/latronax/waveply2149.jpg) :icon_lol:
(clips in reply#21 (http://www.diystompboxes.com/smfforum/index.php?topic=59383.msg464085#msg464085)).
BTW., Gez: aren`t you now heading towards the "normal" class AB complimentary pushpull amp?
(my intentions in this circuitry are purely distortional, so I`m not
that puzzled about "sidenoises" :icon_biggrin:)
Quote from: puretube on July 26, 2007, 08:14:15 AM
BTW., Gez: aren`t you now heading towards the "normal" class AB complimentary pushpull amp?
(my intentions in this circuitry are purely distortional, so I`m not that puzzled about "sidenoises" :icon_biggrin:)
Hmm, possibly (though the drains are still doing all the work)... :icon_smile:
wow, how has this thing evolved...
design is rad and samples sound great!
now, the only mosfets i know (and have) are BS270 and 2n7000, both N-channel ..which are common or good replaces for BS250's (none of the near stores have it)?
edit: by stores i mean 'local stores', smallbear-futurlec-mouser are 'international stores' for me
sorry, nordine,
I don`t have any experience with other types
since that 170/250 combination is the most common one here
(a.o. propagated by "Elektor" over the years...)
BTW.: our local store has closed forever, 2 weeks ago :icon_sad:
and: yes, with bass it can sound very cool - depending on what you expect from a bass-effect, however... :icon_wink:
(I`m very Bootsystic in this matter.)!
mmm.. looks i'll have to look harder for these P channel thingyes, overtones are always welcome on bass guitar.. it the secret weapon for presence (when mids give you only honk)
in the meantime, i had to experiment with this concept, so throwed in some starved tubes (hey keep reading :icon_biggrin:), which is weird at least -being it a tubeless design-, and got a real ugly-ass and mean bass distorter :icon_mrgreen:
Any new info on this? I'm going to have to try it this weekend. I'm wondering if 2 of these would work in a dual Mu-Amp set up like the BSIAB, or driven by an op amp like the Shaka or a Mosfet Boost. :icon_cool:
Sine wave through a 1 stage discrete JFET version:
(http://hometown.aol.co.uk/Gezpaton/JFET+Circuit.JPG)
Softer clipping characteristics than the MOSFET version due to lower transconductance. Also very low current consumption - less than 1mA, and could probably get it lower (will see).
Have only scoped the circuit so no idea how it sounds, but if any good will enter it in this month's competition.
Quote from: gez on October 10, 2007, 12:29:26 PM
Softer clipping characteristics than the MOSFET version due to lower transconductance. Also very low current consumption - less than 1mA, and could probably get it lower (will see).
Have only scoped the circuit so no idea how it sounds, but if any good will enter it in this month's competition.
:icon_cool:
Plugged in the JFET circuit today and it sounds amazing! Didn't have to change a single component value of the circuit I sketched out (love it when that happens)!
At the moment I'm only driving a single stage with an op-amp, but it has a wonderful, natural sound: amp on the edge of breaking up sort of thing. Initially, I was going to sort out a tone control, but it doesn't seem to need it. The reason seems to be the softer clipping: even when driving the JFETs (one n-channel, one p-channel) hard so that the sides square up, the corners are always rounded so there's less hi-end fizz than CMOS circuits.
I expected this to be one of those 'quirk' circuits that I just breadboard, have a little fun with, then move on; but, I think I may end up building a variant of this little beast!
Will post a schematic at the end of the month as a part of The Tone God's competition. Stay tooned...
PS The biasing is different, so don't go subbing JFETs into any of the above MOSFET schematics, they won't work.
Quote from: gez on October 11, 2007, 07:29:32 AM
PS The biasing is different, so don't go subbing JFETs into any of the above MOSFET schematics, they won't work.
mind reader!!! :icon_wink: for quite some time, i've been planning a discrete version of the red llama. :icon_biggrin:
I think we should call the 'new' technology CFET, or possibly CJET (complementary JFET). Unless anyone has a better name? :icon_razz:
Quote from: gez on October 11, 2007, 10:10:05 AM
I think we should call the 'new' technology CFET, or possibly CJET (complementary JFET). Unless anyone has a better name? :icon_razz:
It's push-pull no matter what.
JFET push-pull overdrive.
I have an idea what your circuit may be (a bit like the circuits where RG discusses mu-amps, right? - but a tad different)
But what JFET's did you use? I don't know complementary JFET's as close as in 2N3904 and 2N3906.
Quote from: Steben on October 12, 2007, 05:48:10 AM
Quote from: gez on October 11, 2007, 10:10:05 AM
I think we should call the 'new' technology CFET, or possibly CJET (complementary JFET). Unless anyone has a better name? :icon_razz:
It's push-pull no matter what. JFET push-pull overdrive.
I have an idea what your circuit may be (a bit like the circuits where RG discusses mu-amps, right? - but a tad different)
But what JFET's did you use? I don't know complementary JFET's as close as in 2N3904 and 2N3906.
Well, perhaps the 'C' should have been left out as the JFETs aren't necessarily complementary: I didn't match them, I just used whatever was to hand and incorporated a trimmer for bias. Your name/description is more acurate, I suppose, but a little lengthy. I'll have to have a rethink.
The bare bones of the circuit is exactly the same as an individual CMOS inverter, in that a p-channel device is stacked on top of a n-channel device to form a 'totem-pole'. Both joined at the drain, and the output is taken from the drain. It works on exactly the same principal as a MOSFET inverter, only the biasing for the circuit is a little more complicated (source resistors need to be included for one thing, plus separate feedback networks for each transistor).
I'm still experimenting with it, so don't want to post anything yet, but will definitely enter a version in this month's competition.
QuoteWell, perhaps the 'C' should have been left out as the JFETs aren't necessarily complementary: I didn't match them
maybe not complementary (complimentary?) but maybe oppositely "polarized":
OPFET ?
:icon_smile:
Well, I got the Sansvalve working biased at 4.85v with 9v battery. Removed the feedback loop, it's running open loop I guess. BS170/BS250. (stupid pin outs) Reduced input cap to .001uf. Pretty dark, but smooth distortion.
Driven by a Distortion + type op amp, minus the diodes, back to 100n input cap, feedback loop of 1M resistor with 100pf cap parallel for fizz reduction (probably the op amp distortion contributes to this). Tweaks continue. Thanks for the very cool new "stage" :icon_cool:
Quote from: gez on October 11, 2007, 10:10:05 AM
I think we should call the 'new' technology CFET, or possibly CJET (complementary JFET). Unless anyone has a better name? :icon_razz:
'new'?
http://www.geofex.com/Article_Folders/foolwfets/foolwfets.htm (http://www.geofex.com/Article_Folders/foolwfets/foolwfets.htm)
Some really cool looking JFET circuits that are similar to the concepts discussed here can be found on this page:
http://www.rusblues.ru/articles/tech/tech04.shtml
Pa Ruski, but its totally worth playing with Babelfish to get it figured out. Viktor Kempf has some cool ideas!
Очень интересно!
Quote from: johngreene on October 13, 2007, 08:39:14 PM
Quote from: gez on October 11, 2007, 10:10:05 AM
I think we should call the 'new' technology CFET, or possibly CJET (complementary JFET). Unless anyone has a better name? :icon_razz:
'new'?
http://www.geofex.com/Article_Folders/foolwfets/foolwfets.htm (http://www.geofex.com/Article_Folders/foolwfets/foolwfets.htm)
You'll note that I put the new in
inverted commas, John, thereby acknowledging that it's not new. That aside, the circuit I've devised is 'new' in that the biasing is closer to that used in CMOS inverter circuits. Whether this is responsible for the soft clipping, I don't know: perhaps I've wasted my time reinventing the wheel (hadn't seen RG's article before). I'll breadboard his circuit to make a comparison and report back.
Quote from: gez on October 14, 2007, 03:52:56 AMThat aside, the circuit I've devised is 'new' in that the biasing is closer to that used in CMOS inverter circuits. Whether this is responsible for the soft clipping, I don't know: perhaps I've wasted my time reinventing the wheel (hadn't seen RG's article before). I'll breadboard his circuit to make a comparison and report back.
Well, it seems that I have indeed been reinventing the wheel! RG's circuit exhibits the same soft-clipping characteristics as the one I devised (I used a bypass cap for the p-channel's source resistor in my own circuit and left it in, incidentally). Although there are some advantages to having a feedback network, in the majority of case I'd find it hard to justify the 3 extra components it takes to do this, so well done RG, and thank you John for drawing my attention to his design.
I guess I kinda have a mosfet thing going. The SansValve after the Dist+ without diodes has a really nice "character" to it. It's pretty crispy/crunchy, but has nice fat lows as well. Seems to have lots of compression. I removed the 1K and 100 ohm resistors to no effect, but the parts count is getting lower. Need to try the mods suggested. I have been using this set up with a single Mosfet Boost in place of the SansValve. I'll have to compare after futher tweaking. Thanks again for the new (to me) circuit. :icon_cool:
arrgh - those JoyFets seem to be those devices that seem to vary in pinout from manufacturer to manufacturer... :icon_evil:
GEZ: thanks for all your information, comments, feedback and inspirations!
I got it! :icon_wink:
(in fact it was worth reading/studying paperwork for 3 days on end without finding anything like it...).
The "Starving Pinch Bridge" ... :icon_razz: :icon_razz: :icon_razz:
Ton, not sure what exactly it is that you've got, but I'll defend your right to have it to the death! :icon_razz: :icon_lol:
My rights are Your rights, Sir!
will send you the schemo tomorrow.
3 discrete components, basically - no trimming - 0.5µA @ 9V - instant simulated entubification guaranteed...
(the component values are NO typo!)
(goes under the workname: "puretube`s egg") :icon_mrgreen:
[EDIT]: one active solidstate device...
Quote from: puretube on October 16, 2007, 06:46:02 PM
3 discrete components, basically - no trimming - 0.5µA @ 9V - instant simulated entubification guaranteed...
(the component values are NO typo!)
Well, if the extra parts are for a servo/auto-bias then I
almost beat you in terms of component count. Unfortunately, though, I couldn't stop the circuit from oscillating once AC was decoupled. However, it just occurred to me that if I plumb the signal in via the servo circuit instead of to the gates of the FETs, then it just
might work...doubt it, but one can dream! :icon_lol:
those named 3 components of course do include input and output coupling caps... :icon_wink: :icon_smile:
Quotearrgh - those JoyFets seem to be those devices that seem to vary in pinout from manufacturer to manufacturer...
J201 and MPF102. With those devices, I've nly seen one pinout, which is shared by both (DSG). They give you have access to almost the whole signal JFET universe.
IIRC, there might be a slightly less common Vgs-on range around 3 V, because J201s are mostly higher (less neagative) and MPF102 mostly lower.
cheers
Quote from: gez on October 11, 2007, 07:24:41 AMThe reason seems to be the softer clipping: even when driving the JFETs (one n-channel, one p-channel) hard so that the sides square up, the corners are always rounded so there's less hi-end fizz than CMOS circuits.
It seems that the opposite is true. Onset of clipping is soft, but the output is easily pushed into hard-clipping if the input signal gets 'frisky'. Although this expands the dynamic range somewhat, it doesn't sound very convincing with one stage. Might sound better with 2 stages. Will have to experiment some more...
"JoyFets" soon to be continued in another non-mos thread... :icon_wink:
Quote from: brett on October 17, 2007, 08:57:01 PM
Quotearrgh - those JoyFets seem to be those devices that seem to vary in pinout from manufacturer to manufacturer...
J201 and MPF102. With those devices, I've nly seen one pinout, which is shared by both (DSG). They give you have access to almost the whole signal JFET universe.
IIRC, there might be a slightly less common Vgs-on range around 3 V, because J201s are mostly higher (less neagative) and MPF102 mostly lower.
cheers
gotta love the "pinout" of this Motorola (http://pdf1.alldatasheet.com/datasheet-pdf/view/77364/MOTOROLA/BF256.html) device...
(or here) (http://www.datasheetcatalog.net/datasheets_pdf/B/F/2/5/BF256.shtml)
:icon_rolleyes:
yikes!
maybe it´s a new kind of transistor..the GERMOSBJFET TRIODEY
Hahaha probably some frustrated motorola employee who didn't get his raise.
http://www.aronnelson.com/gallery/v/WGTP/Complement.JPG.html?g2_imageViewsIndex=1
My complements to the Chefs who cooked this up. :icon_cool:
Very cool..hafta try this one.
Anyone tried these? Sound samples? Thanks in advance. :)
grol
Quote from: gez on October 14, 2007, 03:52:56 AM
Quote from: johngreene on October 13, 2007, 08:39:14 PM
Quote from: gez on October 11, 2007, 10:10:05 AM
I think we should call the 'new' technology CFET, or possibly CJET (complementary JFET). Unless anyone has a better name? :icon_razz:
'new'?
http://www.geofex.com/Article_Folders/foolwfets/foolwfets.htm (http://www.geofex.com/Article_Folders/foolwfets/foolwfets.htm)
You'll note that I put the new in inverted commas, John, thereby acknowledging that it's not new. That aside, the circuit I've devised is 'new' in that the biasing is closer to that used in CMOS inverter circuits. Whether this is responsible for the soft clipping, I don't know: perhaps I've wasted my time reinventing the wheel (hadn't seen RG's article before). I'll breadboard his circuit to make a comparison and report back.
Seeing as this thread was revived, might as well give an update.
Although RG's biasing was simpler, I reverted back to my original idea using feedback as part of the biasing. Controlling closed-loop gain enabled me to contain things within the soft clipping zone. Without it, there's a fine line before the amp is pushed into hard clipping (very unmusical as there's no gradual onset). For a workable design a multistage circuit is required, plus a scope and signal generator.
Didn't build a circuit. Unless CMOS chips go the way of the dodo, I'll stick with them as less work is required.
Quote from: puretube on July 19, 2007, 04:18:20 PM
Petri: I had posted some nice basic FET links in an old thread (http://www.diystompboxes.com/smfforum/index.php?topic=29414.msg245542#msg245542),
(see also reply#24, there)
which I had deleted a while later after having been annoyed/molested by the usual gang, for whom I thought
it wasn`t worth pointing to at that time...
I dug them out again for explanations in some other recent threads (http://www.diystompboxes.com/smfforum/index.php?topic=59303.msg463000).
they`re interesting, but don`t reveal all questions:
FET principles & circuits pt.1 (http://www.nutsvolts.com/~downloads/fetmay.pdf),
pt.2 (http://www.nutsvolts.com/~downloads/fetjun.pdf),
pt.3 (http://www.nutsvolts.com/~downloads/fetjul.pdf),
pt.4 (http://www.nutsvolts.com/~downloads/fetaug.pdf), by the great Ray Marston.
Those N&V links don`t seem to work anymore
but excerpts are found here: http://www.uoguelph.ca/~antoon/tutorial/xtor/xtor10/xtor10.html
Quote from: grolschie on May 20, 2008, 01:25:58 AM
Anyone tried these? Sound samples? Thanks in advance. :)
grol
IIRC, there were some more or less crappy U2be clips earlier in this thread?
Obviously the OP has tried out some.
Quote from: gez on May 20, 2008, 03:09:07 AM
Seeing as this thread was revived, might as well give an update.
Although RG's biasing was simpler, I reverted back to my original idea using feedback as part of the biasing. Controlling closed-loop gain enabled me to contain things within the soft clipping zone. Without it, there's a fine line before the amp is pushed into hard clipping (very unmusical as there's no gradual onset). For a workable design a multistage circuit is required, plus a scope and signal generator.
Didn't build a circuit. Unless CMOS chips go the way of the dodo, I'll stick with them as less work is required.
geez, gez, i was hoping for a better outcome. this is really disappointing news, though a really appreciate that you have told us.
cheers, paul
p.s. apologies for the cheap pull on your handle. :icon_twisted: :icon_wink:
Quote from: TELEFUNKON on May 20, 2008, 03:10:30 AM
Quote from: puretube on July 19, 2007, 04:18:20 PM
I dug them out again for explanations in some other recent threads (http://www.diystompboxes.com/smfforum/index.php?topic=59303.msg463000).
they`re interesting, but don`t reveal all questions:
FET principles & circuits pt.1 (http://www.nutsvolts.com/~downloads/fetmay.pdf),
pt.2 (http://www.nutsvolts.com/~downloads/fetjun.pdf),
pt.3 (http://www.nutsvolts.com/~downloads/fetjul.pdf),
pt.4 (http://www.nutsvolts.com/~downloads/fetaug.pdf), by the great Ray Marston.
Those N&V links don`t seem to work anymore
but excerpts are found here: http://www.uoguelph.ca/~antoon/tutorial/xtor/xtor10/xtor10.html
i have copies. here are links:
FET principles & circuits pt.1 (http://gaussmarkov.net/docs/nuts_n_volts/fetmay.pdf),
pt.2 (http://gaussmarkov.net/docs/nuts_n_volts/fetjun.pdf),
pt.3 (http://gaussmarkov.net/docs/nuts_n_volts/fetjul.pdf),
pt.4 (http://gaussmarkov.net/docs/nuts_n_volts/fetaug.pdf), by the great Ray Marston.
Of course, I have a copy, too...
Just ain`t got no rights...
BTW: that "~antoon" link leads to some very nice stuff... Thanx!
Quote from: gaussmarkov on May 20, 2008, 09:16:56 AM
geez, gez, i was hoping for a better outcome. this is really disappointing news, though a really appreciate that you have told us.
Paul, my comments refer to the JFET inverter idea. Nothing wrong with it (sounded good), it's just that I
personally don't see the point of building discrete circuits when there's an easier alternative: CMOS inverter chips. The day they stop making these, then I'll start playing around with JFETs etc.
Quotep.s. apologies for the cheap pull on your handle. :icon_twisted: :icon_wink:
Consider me flushed! :icon_lol:
Quote from: gez on May 20, 2008, 04:00:47 PM
Quote from: gaussmarkov on May 20, 2008, 09:16:56 AM
geez, gez, i was hoping for a better outcome. this is really disappointing news, though a really appreciate that you have told us.
Paul, my comments refer to the JFET inverter idea. Nothing wrong with it (sounded good), it's just that I personally don't see the point of building discrete circuits when there's an easier alternative: CMOS inverter chips. The day they stop making these, then I'll start playing around with JFETs etc.
ah, but you have given us a point already, haven't you? :icon_wink: an asymmetric version? i haven't forgotten, because you scooped me on that one by several years. :icon_biggrin: :icon_cool:
What about the 170/250 MOSFET idea at the beginning of the thread? ??? Or have I missed something? :icon_redface: Thanks in advance. :)
Quote from: TELEFUNKON on May 20, 2008, 03:30:27 AM
Quote from: grolschie on May 20, 2008, 01:25:58 AM
Anyone tried these? Sound samples? Thanks in advance. :)
grol
IIRC, there were some more or less crappy U2be clips earlier in this thread?
Obviously the OP has tried out some.
All "puretube`s" circuits, schemos and "crappy" sound-/video clips until reply#77 are tested, measured 170/250 builds...
(and the reason/origin for this thread explained in 1st post & reply#8)
One of the fine options of the WWW is the clickability of hyperlinx... :icon_wink:
Quote from: puretube on May 21, 2008, 07:56:45 AM
Quote from: TELEFUNKON on May 20, 2008, 03:30:27 AM
Quote from: grolschie on May 20, 2008, 01:25:58 AM
Anyone tried these? Sound samples? Thanks in advance. :)
grol
IIRC, there were some more or less crappy U2be clips earlier in this thread?
Obviously the OP has tried out some.
All "puretube`s" circuits, schemos and "crappy" sound-/video clips until reply#77 are tested, measured 170/250 builds...
(and the reason/origin for this thread explained in 1st post & reply#8)
One of the fine options of the WWW is the clickability of hyperlinx... :icon_wink:
Another fine free thing for all non-illiterates* is the socalled topic- or thread-title (aka: "subject"),
which in this special case says: "Discrete..." as opposed to: "integrated..."
As mentioned in above post,
an explanation for the experiments with 2 complementary discrete MOSFETS was given in reply#8,
and will be repeated in the following quote,
for those who don`t wanna look past the first pic in a thread:
Quote from: puretube on July 18, 2007, 07:11:14 PM
... came up with this coz I didn`t have non-SMD inverters at hand to quickly view...
So it should be clear,
that this whole stuff was not about "emulating tubes with fets",
but: "replacing a CMOS inverter IC with discrete MosFets"
(as far as my circuits are concerned).
And: it should also be clear by now, that those circuits are not an attempt
to make fets sound like tube-amps at all.
On the contrary:
I haven`t witnessed any (pure) tube-amp or (pure) tube-pedal outside my premises,
that would feature most of what those MosFet circuits do, soundwise...
*that come forum-crossing to this thread for the first time
pleez also see replies #24 & #38 for further understanding...