Sola Mark II Pro?

Started by Arn C., September 11, 2003, 08:33:11 AM

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Arn C.

I built this yesterday  according to schematic "w/mods by B. Tremblay & J. Orman applied by RDV"

I used for Q1 & Q2  2n4400's with Hfe of 171 each and for Q3 I used 2n5088 with HFE of 500.

I put 3 pos dip switches for 3 each different value caps for each on input and output.
I adjusted Q3 as per schematic notes (set for 5volts on Q3 collector).
and also trim pots for all three transistors.  
This thing has way too much power where I have it set.  I can hardly turn it up at all and I get feedback.    Would could I adjust to tame it down a bit?
Otherwise it sounds great!
Thanks!
Arn C.

petemoore

Use a lower gain Q3
1 putting something from output fo ground like resistance will DEfinitely down tame anythng.
 2A smaller value volume pot.
3 possibly messing with the Emitter resistor values to reduce gain.
 4adding resistance between the transistors

 I believe most of these fixes are viable, [never actually tried some of them MYs] I usually have the opposite troubles...how to get 'this' thing gained up /enough|!!!
 5 ? 6?
Convention creates following, following creates convention.

RDV

First, I'm glad people are building this thing. :D
It's sounds to me that either there is a slight wiring error, or you've used a linear pot for the volume. An audio 100K is probably what works best there. I've only built the prototype, but too much volume shouldn't be a problem.

Regards

RDV

Arn C.

RDV:
    I double checked the wiring and it is fine.  I used log taper pots for attack and level.  I put trim pots for the collectors of all the transistors and adjusted the first two as Q1=10K  Q2=47K  and Q3 adjusted to read 5 volts.   should I adjust the first two trimpots to lower the gain, if so, would I have to raise the resistance to lower the voltage going to the transistors?  Or should I leave them alone and maybe raise the resistance of Q3?  Or replace Q3 with lower gain transistor?
Thanks!
Arn C.

RDV

Do you have the emitter to ground resistors on all 3 Qs correct?
Also, there should be a lot of gain & feedback with this circuit anyway.

Regards

RDV

Arn C.

Yes there is a lot of gain and feedback!
Yes, all the emitters to ground resistors are okay!
I guess I will fart around until I tame it down a bit.
Thanks for everything!
Arn C.

RDV

Does turning down the attack(fuzz) knob tame it any? There's actually a bit of useful range to it from about 50% on up. It also sounds best to me into a clean amp(like a lot of DIY fuzzes).

Regardley

RDV

Arn C.

Does turning down the attack(fuzz) knob tame it any?  Yes, it works fine.

Just that the Volume is right there when you move it just a tiny bit.

Arn C.

RDV

Are you running into a clean amp, or distorted?

RDV

Arn C.

I tried it through my PA (clean) and through my Montgomery Wards Airline Tube amp volume set at about 4.   I replaced the volume pot with a 50KA.  I will test this and let you know if the volume is more controllable.
Arn C.