JEN DOUBLE SOUND volume drop issue ???

[tubelectron]

JEN DOUBLE SOUND volume drop issue

I recently bought at a reasonable price a minty early 70s JEN Double Sound with her original Vinyl bag :







Here is the inside :



And the Schematic plus matching PCB layout details :





The Fuzz is placed before the Wah, as done on most of those Wah-Fuzz of the era : Arbiter Wah-Face, FoXX FuzzWa, Ibanez Wau-Fuzz, etc...

The problem is : no issue with the Wah itself (it's even a really good sounding one) but when I engage the Fuzz with the Wah(with still a good sound), the volume shows a significant drop in level...

Any ideas ? Would a buffer be between the Fuzz and the Wah ? 

Thanks for your input, Guys ! 

A+!

[GibsonGM]

One option (very common) is to play with the value of R14 (increase it...1.2k perhaps).  This is the 'fuzz central' approach to getting more level out of a FF...I do this to my fuzzes and like them much better!

https://fuzzcentral.ssguitar.com/axisface.php

[tubelectron]

One option (very common) is to play with the value of R14 (increase it...1.2k perhaps).  This is the 'fuzz central' approach to getting more level out of a FF...I do this to my fuzzes and like them much better!

https://fuzzcentral.ssguitar.com/axisface.php

Thanks @GibsonGM ! 

I see - You mean this :

Another common problem with the Fuzz Face is that there just isn't enough output level. In order to get the pedal good and loud, you would normally have to crank the "Volume" pot up to about 2 o'clock or so. To fix this, I've replaced the 330-ohm resistor that's in the Silicon Fuzz Face with a 1K2 resistor. This gives the pedal quite a bit of volume boost so that it's good and loud by 11 o'clock in the rotation of the "Level" pot.

Extracted from the text on the link you provided me... Good and simple idea ! 

I will indeed test it, but by your experience : beside the volume increase, does it changes the amount of Fuzz effect of not ? is it significant ?

I have also the idea of reducing R17 18K to a lower value, hoping that it would increase the output volume of the Fuzz. But this resistor may act also as an oscillation suppressor, in order to avoid the tandem Fuzz-to-Wah to howl ? Did you experimented that way too ?

Thanks to let me know... 

A+!

[GibsonGM]

I've never noticed any 'loss of fuzz' by changing the "R14 resistor" to a higher value, at all.  My fuzzes always need to be turned back from 12:00 on the pot to 11 or so to be useable, so I'd say it affects it very little.

I suspect that yes, the 18k is there for stability, equivalent of a 'grid stopper' maybe...not sure how it plays with the fuzz output impedance (strange in a way).  I wouldn't hesitate to see what lowering it does - you could jumper a wire across it to take it out of the circuit, see what that does.   But I think by just substituting a 1.2k for R14 you might be happy     

My instinct with such a clean box is to do very little to it, just get the volume where you want it to be...my 2 cents...maybe by working out the parallel R needed to get 1.2k, and leave the original one in place, piggyback the new one so it can be cleanly removed later if you want... 

[ThermionicScott]

You can't raise the value of R14 by adding a resistor in parallel with it.    You'll have to take out the 270-ohm, but I don't think you'll regret it.

Changing the value of the resistor will affect the bias, but you'll have to try it and see whether it makes enough difference to warrant futzing with R13 as well.

[tubelectron]

Thank you, Guys ! 

My instinct with such a clean box is to do very little to it, just get the volume where you want it to be

I agree absolutely : preservation is the rule, so a non-intrusive, easily removable mod is way preferable  . That's why I am very relunctant to add any buffer anywhere inside... 

What you suggest in the posts above is just fine  . I just want to balance the output volume between Wah and Fuzz+Wah functions.

I will test these options and report back ! 

A+!

[GibsonGM]

You can't raise the value of R14 by adding a resistor in parallel with it.    You'll have to take out the 270-ohm, but I don't think you'll regret it.

Ha ha, brain cramp. 

[tubelectron]

OK Guys !

The suggestion from @GibsonGM works fine : raising the value of R14=270R to 390R give the requested compensation in volume. 



I noticed an oddity about my JEN Double Sound  :

I thought that - like on many (not to say most) Fuzz-Wah pedals - the FUZZ section, when engaged, was preceeding in serie the WAH section : I was wrong.

The Double Sound has her FUZZ section, when engaged, which is connected in parallel with the WAH section. I rechecked  to be sure and I confirm that // disposition, and the wiring is fully factory-stock.

I read this point somewhere, and did not believed it first, but now I can say that's true...

Were all JEN Double Sound factory-stock wired in parallel ? I don't know  ... It seems that there's not much litterature about them.

Another point of importance : whithout surprise, this pedal needs to be rewired TBP to avoid the well known treble tone sucking often found on vintage wah pedals...

So there's a little bit of work to do on it ! 

A+!

[ElectricDruid]

That schematic is wrong then!! That's pretty clearly series, fuzz first.

Still, it wouldn't be the first time that a widely-circulated schematic was way off the mark!

Lovely old pedal. Nice find.

[anotherjim]

R17 maybe makes more sense if it's from the wah pot output to the fuzz input.

[ElectricDruid]

One other thing i notice about that schematic:

Assuming SW1 is the toggle, switching the fuzz in or out, that leaves SW2 as the footswitch. The two options for that are then Off/Wah and Fuzz Only/Fuzz+Wah for the other toggle position. E.g. if you have the fuzz switched on, you can't have the effect off. That's suspicious, and certainly suggests to me it might be a badly traced schematic.

[duck_arse]

as drawn, S2 connects nothing to the output, or the wah input AND the top of the wah pot to the output at the same time. can't work like that. S2 should probably be drawn with one pair closed, the other open.

[ElectricDruid]

as drawn, S2 connects nothing to the output, or the wah input AND the top of the wah pot to the output at the same time. can't work like that. S2 should probably be drawn with one pair closed, the other open.

Good spot! The number of errors in that schematic is starting to stack up!

[tubelectron]

Yes, Guys ! 

The schematic is indeed wrong about the FXs and SWs arrangement, but fortunately is correct about the values and the circuits of the two effects : everything matches in my pedal - with the exception of the transistors (see my layout for references).

I rewired it in TBP, by displacing only two wires on the FSW, and it works fine without tone sucking anymore. 

That said, despite cleaning, the pot needs to be replaced and possibly the FSW, as they show wear and noise. These parts are on order...

This relaunches on sleeping/lagging wah projects... So Wait and See ! 

A+!

[pacealot]

My understanding is that Double Sound pedals have been found "in the wild" with either series or parallel wiring from stock, so it's possible that the schematic was drawn from a specific series-wired example.

[tubelectron]

My understanding is that Double Sound pedals have been found "in the wild" with either series or parallel wiring from stock, so it's possible that the schematic was drawn from a specific series-wired example.

Yes, possibly - I don't know, in fact...

Funny thing : I removed the original Wah pot of the Double Sound, and while it was marked 100K/S, meaning it is a 100Kohms value with a S taper, I measured it at 1.5M, with a S- curve variation from 100K to 1M between 25 and 35% or the total rotation...

OK, so I put a B125K Wah pot instead, and the wah sweep - while spreaded - wasn't wide enough, I mean going enough in the treble or the bass Wah tones. Clearly, this denotes that the pot value at 1.5M offered the right sweep width, but then, why the original pot was marked 100K ? 

This inconsistency is uzzling... 

A+!

[Alban88]

Hi everyone!

A few months ago, I bought the same model. Found in a flea market for really cheap.
The guy told me that it didn't work anymore but that there might be a way to fix it.

I have absolutely no knowledge of circuits, fuses, etc. But for the price, I thought I'd give it a try.

Once I got into it, I realized that it's not in my capabilities at all, I've probably definitely screwed it up

[PRR]

Welcome!

So what have you tried? What do you see? What exactly is "don't work"? Hiss? Hum? Peruvian radio? No guitar? Dead-nuts nothing at all? Any loose bits bopping around inside?

[KaenaB]

Hi all!

I recently acquired a Jen Double Sound with non working fuzz circuit. A transistor was replaced, some rewiring done, fixed a trace and now it works! 

When switched to the fuzz-wah position, I get FSW DOWN > fuzz-wah; FSW UP > clean signal with a lot less treble, which is kind of nice for jazz but not what I want.

I would like to have only the fuzz in the FSW UP position but I can't figure out what I need to do.

Would be great if anyone could help me with this, thanks!

Here's a picture of the wiring.

[antonis]

Let us see of what we're talking about..





So what exactly do you want..??