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soupbone · August 28, 2011, 01:42:57 PM

My friend gave me a Boss DS-2 Turbo Distortion,and I'm going try modding it,Just for the heck of it

.My main goal is to get rid of the nasaly sound on the "Turbo 2" channel,and boost the mids on the regular channel.Any help on this would be great!Here's the schematic;http://www.freeinfosociety.com/electronics/schemview.php?id=132

Electron Tornado · August 28, 2011, 01:54:37 PM

Try changing C12, C40, and possibly C39 from 0.047uf to 0.1uf. Test it after changing C12 and C40 and see what you think. Then try changing C39.

soupbone · August 28, 2011, 07:17:15 PM

Quote from: Electron Tornado on August 28, 2011, 01:54:37 PM
Try changing C12, C40, and possibly C39 from 0.047uf to 0.1uf. Test it after changing C12 and C40 and see what you think. Then try changing C39.

Nice!What are these changes doing exactly?Also,What are you changing C12-C40 too?

Electron Tornado · August 29, 2011, 02:05:07 AM

Look at the schematic. Those three caps are all 0.047uf. Change them to 0.1uf. Do C12 and C40 first and see what you think. By increasing the value of those caps, you are letting more low frequencies through. Those are simple things that I would try first.

Hopefully someone smarter than me will chime in with more suggestions. If they do, hopefully they will discuss C43, C44, and C45, along with C28 and C21, and maybe even C32 and C34. (For C34, it looks like increasing its value will result more clipping of lower freqs by D8 and D9. I think C32 is filtering some highs so they don't get clipped.)

Slightly off topic, it's an interesting circuit. I can see the FETs being used in the bypass circuitry. It looks like FETs Q10, Q14, Q15, and Q20 are also being used as switches being controlled by BJTs Q8 and Q9 in conjunction with the Turbo switch or an external Remote switch. Ah, so which switches are opened and which are closed for each position of the Turbo switch? I'll just take a gander that Q10, Q14, and Q20 are all switched to the same state (closed or open) together, while Q15 will be switched to the opposite state. Taking another gander makes me think that with Q20 closed, you'll get more clipping from diodes D8 and D9.

OK, now look what you've done, soupbone, now I've got a bunch of questions about this circuit.

Quackzed · August 29, 2011, 02:21:48 AM

that schem is an eyefull man! "discrete opamps", all kinds of strange filtering?!? yikes! if you want a down and dirty idea of whats happeining in the tone cntrl section, jump it! that is, connect an alligator clip from after c36 to the junction of r45/r46! not perfect but an idea of what the tone stack thing is doing! you have the right idea in that you dont like the eqing going on, try jumping over it and see what you get... after that its a question of raising/lowerig caps and resistors in the tone section... so jump it, seewhat the straightish signal sounds like, then parallel each cap with an equalish in value, see what it does- keep notes!- and generally get a better base line idea of what adds bass/treble, and what reduces them! then tune to taste!

soupbone · August 29, 2011, 02:55:07 AM

Quote from: Electron Tornado on August 29, 2011, 02:05:07 AM
Look at the schematic. Those three caps are all 0.047uf. Change them to 0.1uf. Do C12 and C40 first and see what you think. By increasing the value of those caps, you are letting more low frequencies through. Those are simple things that I would try first.

Hopefully someone smarter than me will chime in with more suggestions. If they do, hopefully they will discuss C43, C44, and C45, along with C28 and C21, and maybe even C32 and C34. (For C34, it looks like increasing its value will result more clipping of lower freqs by D8 and D9. I think C32 is filtering some highs so they don't get clipped.)

Slightly off topic, it's an interesting circuit. I can see the FETs being used in the bypass circuitry. It looks like FETs Q10, Q14, Q15, and Q20 are also being used as switches being controlled by BJTs Q8 and Q9 in conjunction with the Turbo switch or an external Remote switch. Ah, so which switches are opened and which are closed for each position of the Turbo switch? I'll just take a gander that Q10, Q14, and Q20 are all switched to the same state (closed or open) together, while Q15 will be switched to the opposite state. Taking another gander makes me think that with Q20 closed, you'll get more clipping from diodes D8 and D9.

OK, now look what you've done, soupbone, now I've got a bunch of questions about this circuit.

Sweet!When you talk about Q20 closed,Are meaning take it out of the circuit?

soupbone · August 29, 2011, 03:10:04 AM

Quote from: Quackzed on August 29, 2011, 02:21:48 AM
that schem is an eyefull man! "discrete opamps", all kinds of strange filtering?!? yikes! if you want a down and dirty idea of whats happeining in the tone cntrl section, jump it! that is, connect an alligator clip from after c36 to the junction of r45/r46! not perfect but an idea of what the tone stack thing is doing! you have the right idea in that you dont like the eqing going on, try jumping over it and see what you get... after that its a question of raising/lowerig caps and resistors in the tone section... so jump it, seewhat the straightish signal sounds like, then parallel each cap with an equalish in value, see what it does- keep notes!- and generally get a better base line idea of what adds bass/treble, and what reduces them! then tune to taste!

Sorry Quacked,I sort of understand what your saying.When you said connect an alligator clip after C36,Are you meaning any cap after that one?Also,You said to the junction of R45-46.Do you mean just taking the other end of the alligator and clipping it to one of the legs of both resistors?Sorry,For all the questions!

Electron Tornado · August 29, 2011, 03:52:11 AM

Quote from: Quackzed on August 29, 2011, 02:21:48 AM
if you want a down and dirty idea of whats happeining in the tone cntrl section, jump it! that is, connect an alligator clip from after c36 to the junction of r45/r46! not perfect but an idea of what the tone stack thing is doing!

The tone control circuit is only a part of the overall frequency response of a pedal. I've changed that on pedals without ever touching the tone control circuit.

Quote from: soupbone on August 29, 2011, 02:55:07 AM
Sweet!When you talk about Q20 closed,Are meaning take it out of the circuit?

No. That FET is being used as a switch. When a switch is closed it completes a circuit, when it's open it breaks a circuit. When Q20, is closed, you could replace it with a simple wire between the source and drain. When it's open, it's as if it was simply removed from the circuit.

Here's another example. Q3, Q4, and Q21 are also used as switches. With Q4 and Q21 closed, and Q3 open, the pedal is engaged, but with Q4 and Q21 open, and Q3 closed, the pedal is in bypass.

Hope this helps.

EATyourGuitar · August 29, 2011, 10:41:57 AM

I haven't looked at it but jumpering the tone stack is not always perfect since you may still have bleeding through the caps to ground making a simple low pass filter. you need to break a trace on either side of the cap to ground. thats the real test.

Electron Tornado · August 30, 2011, 07:00:46 PM

I had a chance to play through one of these last night. Kind of liked the tone on the "Turbo II" setting. It sounds like when it's on that setting that Q15 is open, and Q10, Q14, and Q20 are closed.

So, here's a couple of questions:

1. How does the switching circuit made up of Q8 and Q9 work?

2. What is the purpose of the circuit made up of Q23?

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