Orange Bass Butler  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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bajaman
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Post by bajaman »

Hi Tuck
i already corrected the schematic and pcb P2 and P3 error on the last version i uploaded !
cheers
bajaman
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tuck
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Post by tuck »

Woops... you are right!
I noticed that timol mentioned it...

But I couldn't find this:
c31.PNG

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Post by tuck »

In the latest schematic C7 is still upside down.
c7.PNG
c7.PNG (7.25 KiB) Viewed 826449 times
And because I don't have the latest gerber files C4 seems to be not matching the schematic. Pin 6&7
ic4.PNG
ic4.PNG (107.71 KiB) Viewed 826449 times
Other than that Kicad does not complain about anything else. every connection is drawn according to your pcb and there is no unconnected pad left :-)

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Post by bajaman »

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

Any chance we could get a PDF of the final schematic here on the thread so I can look at it on my phone? (Sprint is on my computer and won't be able to view it until this weekend).

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tuck
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Post by tuck »

bassbutler final corrected 3.pdf
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Post by tuck »

I switched the two Gain pots but that was just to get the correct connections in PcbNew (pcb designer) of Kicad
green is the latest version, red mine to have the correct connections
gain.PNG
Also the switching was changed a bit because I noticed that I did not have the FSG in the earliest schematic
green is the latest version, red mine to have the FSG pad on the PCB
switch.PNG
This is how the switching should be. A neverending story

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tuck
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Post by tuck »

@bajaman I‘m just reviewing some comments.
What did you mean with this?
bajaman wrote: 10 Dec 2022, 23:22 the drive channel looks ok at this point except for the footswitch connection ;-)
I may be to blind to see the difference to the original schematic.

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Post by bajaman »

footswitch was connected to wrong side of C17 etc
compare your original with final correction 3 ;-)
cheers
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Post by tuck »

.

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Post by tuck »

What brand are the red caps like C15?
Maybe Panasonic ECQE? But I think the lead spacing might be not correct.

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Post by tuck »

As a reminder: the groudn lift switch is missing so far. If needed connect it on the XLR out ( green wire in the picture on the first page).

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Post by Tassieviking »

I just noticed this one, I love it, great work.

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Post by tuck »

Parts are here, PCB still in production...

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Post by Tassieviking »

Tuck, what FET's are you using for this build ?
It looks like you are using TO-92 Fet's.
I would give this one a go myself if I can find a substitute for the MMBFJ201 surface mount Fet's.
My eyesight is not the best any more and arthritis in the fingers does not help either.
Not many TO-92 Fet's left any more that can be used as far as I know.

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Post by tuck »

I have a few J201 in my drawer. It's time to use them as long as they are no fakes.... I bought them years ago.

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Post by tuck »

A65F2918-76CC-4BDC-91C2-96D56312043A.jpeg
The clean channel works, the dirt channel not so much. The J201
drain voltages are ~12V for clean.
The J201 for distortion only have 1 to 4V.
Will check again.
I messed up the pins on the J201 footprints but already bent some legs to correct this issue…

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Post by tuck »

The dirt channel kind of works, I forgot to add the expression jack. But it's very, very low in volume and there is no distortion.
The resistor and pot values are ok.
I used a cheap component tester to check all the J201. Are these reasonable values?
Drain voltage at the end. When I unplug a transistor I get around 15V on the pin header where the drain pin should be.

edit: Idss seems way off according to the datasheet.

Code: Select all

Q1 Idss 0,1mA  I 0,90mA Vg 0,62V  14,6V
Q2 Idss 2,2mA  I 0,94mA Vg 0,65V  1,16V
Q3 Idss 1,1mA  I 0,54mA Vg 0,38V  4,40V
Q4 Idss 1,9mA  I 0,82mA Vg 0,57V  1,27V
Q5 Idss 0,86mA I 0,48mA Vg 0,33V  5,4V
Q6 Idss 2,9mA  I 1,2mA  Vg 0,82V  14,02V
My messed up transistors in the schematic and on the pcb. So I turned the transistors and bent each source pin outwards.
butler_j201.png
IMG_5247.jpg

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Post by bmxguitarsbmx »

Is it possible that your Source resistors are a magnitude off? Like 15k instead of 1.5k?

J201's should have a very tight grouping and align with the data sheet. I sorted 500 j201's and I found no outliers, granted I bought my j201's back when they were 5 cents each.

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Post by 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 NEVER by semiconductor devices from Aliexpress having been bitten far too many times - charge pumps that whine because they operate at too low frequency, 16A power transistors that have difficulty switching more than an Amp etc.
As a rule of thumb, I like to bias my jfets at approximately 2/3 of the supply voltage - in this case set the drains to around 10v dc - you can either adjust the drain resistor (preferred) or the source resistor - if you have a lot of jfets, just start with the first stage and try inserting one after the other until you find one that biases up near 10 volts at the drain terminal.
I hope these suggestions work - keep going - it looks like a nice compact build
cheers
bajaman
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