I spent some time with the bass butler build and the more i played with it the less i liked the drive section - the clean channel works brilliantly - the compressor works well and the tone controls are smooth acting and overall do exactly what is required, BUT, that drive channel sounds scratchy and...

yet another update: I tested a few more of the smd MMBFJ201 I had in stock and the 0.21mA Id one i originally tested was on the low end of the scale it seems - after testing four more with my TC1 tester they measured: 1/ 0.36mA Id@243mV Vg 2/ 0.4mA Id@ 280mV Vg 3/ 0.37mA Id@ 257mV Vg 4/ 0.38mV Id@ 2...

I can now confirm that the compressor section works with the Chinese VTL clones, although it is not a compressor it functions more like a limiter - above a certain input (threshold) level the signal level remains the same despite adding more gain from the compressor control With respect to the fake ...

Hello Tuck yes - exactly like the Ampeg ;-) You could always remove the input jfet buffer and connect the input socket directly to the normal/bright switch - in this case you would have to scale up the resistor values x10 (100k, 47k, and 5M6) and decrease the capacitor value x10 (220p) - then it wil...

Hello Tuck The way you have wired the switch is correct BUT, it has been so long ago that i designed this pedal and upon investigation of the Ampeg SVT schematic the 220n capacitor is far too large to be effective - it should 4.7nF ! Also i would suggest changing the 330k for a 560k resistor, althou...

Hi Temol I am using these: https://www.aliexpress.com/premium/VTL5.html?spm=a2g0o.order_list.1000002.0&initiative_id=SB_20230301114959&dida=y They use a red led and seem to work fine in most circuits - my problem with the bass butler at the moment, is that I don't seem to be getting enough s...

IMPORTANT I am still working on my bass butler build - mostly working well, but still a bit more work to get the compressor working as i would like - a work in progress ;-) However: i have found some mistakes in the schematic for three of the resistor values in the clean section DI out. According to...

Hello Tuck
Thanks for that information - I did not know of the T4 existence and unlike my TC1, it displays the idss of the jfet which is a much better piece of information ! - I have just ordered one from China
cheers
bajaman

Here is some hopefully helpful advice to those using J201 njfets As i mentioned previously in this thread, it is usual practice to bias the jfet similar to the triode vacuum tube - bias to approximately 2/3 of the supply voltage. So if you are using an 18 volt supply rail you would ideally adjust th...

Hi folks I edited Tuck's Kicad pcb layout - imported his gerber and drill files into Sprint Layout V6.0 and made the traces a little wider and generally tidied up the distance between tracks and pads - still essentially the same - I sent the gerbers off to the fab house and have a few spare boards (...

sorry - i do not have a pcb for this project
cheers
bajaman

Hi Tuck
Okay - I do the same with my pcb layouts to CorelDraw
So the actual print was done with a commercial laser printed direct to enclosure service ? How much did that cost for a one off, if you don't mind me asking ?
cheers bajaman

What did you use for your front panel label Tuck ?
It looks real nice
cheers bajaman

I downloaded the zip file - opened Kicad beta version 7 and saved the project's gerber files. Then I opened my trusty favourite Sprint layout V6.0 and imported the saved gerbers and drill data - i had to do a little editing but eventually came up with this - i manually tidied up the track routing an...

Hi Tuck
Just choose the best J201 you have (the ones that bias up closest to 10v dc) and adjust the drain trim pot (100k)(R5) - ok, in theory this alters the gain, but with 4 cascaded stages there will always be more than enough to give you some nice jfet crunch
cheers
bajaman

hello karter2000 - yes

Hi Tuck - in the meantime, you could always adjust the drain resistors (R10,17,25,30 ) for the jfets that get you closest to 10v dc at the drain (your measured Q3 and Q5 would be ideal candidates) - try a 100k trim pot and see how you go

cheers
bajaman

Hi Tuck some further suggestions: buy some genuine MMBFJ201 smd parts from Radiospares, Element 14, Mouser or Digikey and make some pcb adapters to fit them in place of the through hole parts - if you purchased your through hole J201 from China you will probably have counterfeit devices - I will NEV...

footswitch was connected to wrong side of C17 etc
compare your original with final correction 3
cheers
bajaman

Ok Tuck
Thanks for those corrections
here are hopefully the final schematic and sprint layout pcb gerber files cheers
bajaman