Krankenstien FET version from GT labs

[twabelljr]

I love crunchy, gritty palm muting and pinch harmonics. Awesome job! Gonna start gathering parts now. 

[euronymous0001]

brymus

where is the gain pot on your final version? 

[Brymus]

brymus

where is the gain pot on your final version? 

It doesnt have one.
The way the MOSFETs are biased it doesnt work the way its drawn on the schematics.
So the circuit works/sounds alot better with out it.
You can use the volume on your guitar,or
You could probably add a JFET voltage follower(buffer) after Q1 and stick it in between Q1 and the JFET voltage follower.

Also I would experiment with the EQ values,I think it could be alot better.
I just wanted to verify the schematics ,and see how close they sound to the sound clips that were posted at GT labs forum.

Also :If you try this, check all your volatges then strum your guitar and turn the trimmer between Q3 and Q4 as you will only get sound in one small part of the travel.
Only the Krankenstien version has this issue,due to the way Q4 is set up,to sound like the actual Krankenstien tube version.

Also:
I have had a couple of PM's wanting to know my PCB layout  - I didn't make a PCB or pedal I simply breadboarded the circuit
and recorded it that way.
The buzzfall layout will work for any of the schematics on that page at GT labs.
http://www.guitarjfet.ru/index.php?option=com_content&task=view&id=30&Itemid=34

Just keep in mind there is also a clean channel on that layout,which is why there are two extra FETS on the PCB.
Also the 4th leg on the Russian FETs is a ground connection,so dont let that throw you off.

[euronymous0001]

brymus

where is the gain pot on your final version? 

It doesnt have one.
The way the MOSFETs are biased it doesnt work the way its drawn on the schematics.
So the circuit works/sounds alot better with out it.
You can use the volume on your guitar,or
You could probably add a JFET voltage follower(buffer) after Q1 and stick it in between Q1 and the JFET voltage follower.

how is "a lot better" sounds compared to the one with gain?

i tried to create a layout following the buzzefall and i was aware of the 4-legged fets and also with the clean channelof the layout.
thanks for the replies!

[Brymus]

I recorded it the way it is on the schematic.
BUT

I discovered I had a bad treble pot,while working on the SLO 100 fet pedal.(same pots I used for the Krankenstien)
Now the EQ works way better, so I am going to have to re-bread board this again.
thats OK I want to try with a voltage follower after Q1 so it can have a proper gain pot.

Listen to how tight the SLO 100 fet pedal sounds,
I KNOW the Krankenstien can sound better with a proper treble pot...DOH stupid ,stupid, Bry
http://www.aronnelson.com/gallery/main.php/v/Brymus/Modern+SLO+100+FET+version/MoP+SLO+100+pedal+_GX20M_JensenJets.mp3.html

[joegagan]

great clips. cool sounding pedal for sure.

i like the way you posted your lab notes. good example for the rest of us lazy bastards

[twabelljr]

Bryan, I like your work. Soundclips kick *ss!! Keep it up.
+1 on the lab notes. Thanks.

[audioguy]

Has anyone knocked out any layouts for the GTlabs stuff? Looks amazing... and being a gain freeeek I look forward to building this bad boy.

OOPS... I just re-read the post stating that the GT emus can be built on the Buzzefall layout. I'll give that a stab.

Quick question- what layout software opens the .lay file?

[euronymous0001]

Quick question- what layout software opens the .lay file?

Sprint Layout 

[audioguy]

Found Sprint... now the 4 legged V's have me confused.. and I don't see where the tone stack would go on that layout. I'm really hoping to get this figured out, because all of those schemes sounded fun!!

[euronymous0001]

Found Sprint... now the 4 legged V's have me confused.. and I don't see where the tone stack would go on that layout. I'm really hoping to get this figured out, because all of those schemes sounded fun!!

tonestack is not on the layout, look for the "3" to the left of R23, that goes to the TS (R26 R27 C22)
lug 2 of your treble would go to "6"  to the left of R24 (atop VOL pot).

as for the 4 legged trannies, i think brymus also stated this earlier that one would go to ground (the pad below the "1" of V1 of the first tranny)

[audioguy]

Now I've got to FIND those trannies! hahaha Thanks for the help.

[audioguy]

Also, what would the 5 pad be above C25. you can see 3 pads there... hmm

NOW I'M CONFUSED...
I just looked at the SLO100 from GTLabs... and it looks like those 4 legged trannies are subbed with J201s- how in the world do I make that work.

[euronymous0001]

Also, what would the 5 pad be above C25. you can see 3 pads there... hmm

5 pad is the OUT, going to the switch or output jack. this has a buffer so OUT is not directly from lug 2 of the VOL pot.

NOW I'M CONFUSED...
I just looked at the SLO100 from GTLabs... and it looks like those 4 legged trannies are subbed with J201s- how in the world do I make that work.

just ignore the ground pad on those trannies 

[Maik]

Could someone build it and post the correct layout/pcb?
It´s too dificult for me but I wanna have...

[Brymus]

great clips. cool sounding pedal for sure.

i like the way you posted your lab notes. good example for the rest of us lazy bastards

Thank you that means alot coming from you Joe !

Bryan, I like your work. Soundclips kick *ss!! Keep it up.
+1 on the lab notes. Thanks.

Thank you !

Quick question- what layout software opens the .lay file?

Sprint Layout 

Download Sprint layout here http://www.abacom-online.de/uk/html/demoversionen.html
Thanks for the tip,after downloading Sprint Viewer and printing the trace layer it will definetly fit in a 1590BB enclosure.

NOTES:
I have re-breadboarded this and the EQ from the original schematic works fine - I did use a 1M5 Bass pot for more low end though,and I also kept the "presence" from the SLO 100 (on a switch with a 100K pot for fine tuning)

The gain pot,man oh man this is giving me a headache....
I did verify that adding a follower after Q1 and inserting a pot between Q1 and the follower works,
As does using a 100K as a variable resistor to ground like on my re-touched schematic.

Right now I am using a 470uf cap on leg 3 of the gain pot to ground.
This bleeds off the AC signal, without altering the DC levels in the circuit.

I made a regulated power supply and dialed my voltages in even closer to the ones on the schematic,right now my voltages are with in .02V of those posted on the original version.

I added the buffered bypass section,you will notice it is tied gate to gate with Q1 (Q1 and Q7 are connected at the gates)
This effects the voltages too...

It is sounding really good at this point,so I am going to break out my O-scope and signal generator and see whats going on.
I am going to try and match what Old Mike did in his blog here.
http://gtlab.net/gtlab4/archives/216
He states that the best way  (from the Windows Live translation) is to set the bias of each stage with the scope,although the designs we are all familiar with, are supposed more forgiving,but less acurate.(meaning you dont need the scope to set them up)
Anyone interested in these FET emulations should translate and read that page !!!

I am working on a new/revised layout ,I have traced the buzzfall layout (prior to finding out about Sprint)
And am going to make it so the gain pot works right,and hopefully add all the EQ and pots to the PCB to simplify wiring and reduce noise.
When it's done I will post it for everyone to use.
I plan to etch and build this ,as it Freakin rocks !

[euronymous0001]

did you try to have the gain pot go to ground instead of the vref?

[askwho69]

[audioguy]

I am working on a new/revised layout ,I have traced the buzzfall layout (prior to finding out about Sprint)
And am going to make it so the gain pot works right,and hopefully add all the EQ and pots to the PCB to simplify wiring and reduce noise.
When it's done I will post it for everyone to use.
I plan to etch and build this ,as it Freakin rocks !

This would kick ass... would love a full layout. will yours be able to accommodate the other circuits at GTLabs?

[Brymus]

Uhm yeah, running the gain pot to ground instead of Vref was the first thing I tried.
But I think it sounds better using a cap to bleed the AC and keep the DC Vref stabilized at the same time.
I honestly thought (still think its possible) that the voltage bleed (when goingto ground or Vref) could be part of the voltage scaling design.
But out of running it to Vref ,or straight to ground, or via a cap to ground.
I think that latter the best sounding.

I am working on a new/revised layout ,I have traced the buzzfall layout (prior to finding out about Sprint)
And am going to make it so the gain pot works right,and hopefully add all the EQ and pots to the PCB to simplify wiring and reduce noise.
When it's done I will post it for everyone to use.
I plan to etch and build this ,as it Freakin rocks !

This would kick ass... would love a full layout. will yours be able to accommodate the other circuits at GTLabs?

In as much as the buzzfall layout does,yes. I decided revised is going to take less time than new. 
I am just modifying it to include a few changes and the EQ section,trying to get as many pots as possible pcb mounted.
I dont think mine will allow for a 9V battery in the 1590BB enclosure though.
There are 7 pots if you include sweep,and presence.
I would rather lose the battery and have a regulated power supply and board mounted pots.

After finishing (last month) my Dr Boogie I started for the 666 competition, I would much,much rather have as much as possible board mounted.