Danelectro Tuna Melt - increase volume

[ilcaccillo]

Hello,
I'm re-housing 2 tuna melt pedals,
I already removed the uneedded components and re-house the units.
I have a volume drop when the circuit is activated, I would like to bring the circuit gain a bit higher.


Schematic 1, in red squares are the components that need to be removed for the re-house with true bypass switching (R5 should be removed also):




Schematic 2, circuit with the original switching circuit removed:



My present schematic is "Schematic 2"
Could you please help me in what values I would need to change to increase the gain of the circuit, so I don't have a volume drop when the effect engaged?

If the circuit was stock, people say to change the values of R120 and R102.
But with the re-house R120 is removed from the circuit, so I dont know how to proceed.

Thank you so much

[cortezthekiller]

If you replace R102 with a 50K trimpot you should be able to dial in the volume to your liking.
It will adjust the gain of the last op-amp stage.
This is the same approach used the the Tremulus Lune tremolo pedal.

[ilcaccillo]

If you replace R102 with a 50K trimpot you should be able to dial in the volume to your liking.
It will adjust the gain of the last op-amp stage.
This is the same approach used the the Tremulus Lune tremolo pedal.

Hi,
I did that and it didn't work.

The Volume doens't change, it only changes when you reach 0 ohms and cuts the sound then

[ilcaccillo]

I tried a 100K Pot,
and that worked, I choose the position I liked the volume and then measured the pot.

63K , it's a strange value it seems too high, I would expect the same thing as you suggested that the 50K would have more than enough range to increase a lot the volume.

Well anyway, it works for my needs with a 63K resistor there.
Soldered the resistor and done with that.

Now I just have to solve the terrible POPs I get when I activate the effects on/off.
Horrible Popping sounds, I tried all the main tricks to solve it and none work, think I have to rest and come back to it fresh in another day.

Thanks

[bluebunny]

Now I just have to solve the terrible POPs I get when I activate the effects on/off.
Horrible Popping sounds, I tried all the main tricks to solve it and none work, think I have to rest and come back to it fresh in another day.

Which "main tricks"?  The output already has a DC path to ground, so I would just have tried a large resistor (e.g. 1M) to ground before the input cap.

[ilcaccillo]

Now I just have to solve the terrible POPs I get when I activate the effects on/off.
Horrible Popping sounds, I tried all the main tricks to solve it and none work, think I have to rest and come back to it fresh in another day.

Which "main tricks"?  The output already has a DC path to ground, so I would just have tried a large resistor (e.g. 1M) to ground before the input cap.

Main Tricks tried:

1) 1M to ground after the output cap

2) 1M to ground before the input cap

3) Resistor in series with the input

4) disconnecting the LED

5) Changing the switch for another brand and quality

[pinkjimiphoton]

discarding the input/output boards, ya lose the buffers there. you may need to add a buffer back to the circuit to get it to work well.

it sounds to me like a microphonic solder joint or component. with it plugged in, whack each component you did with a guitar pick or pencil or something. when ya find what makes a noise, thats likely your culprit.usually its a bad joint on a cap or resistor, usually near a cap. caps become piezos if not solidly connected <not really piezos, but they do get quite microphonic>

[antonis]

Don't bother..
(wrong posting)

[ilcaccillo]

it sounds to me like a microphonic solder joint or component.

Thanks

Retouched all the solders, that were pretty good already, touched with the wood stick in all the components.

It's definitelly not a cold solder joint. it has to do with the circuit

[ilcaccillo]

If you want to keep LDR as it is, you have to replace Q1 with another BJT of higher gain (maybe a Darlington) to lower enough buffer's output impedance, due to lower reflected signal source resistance..

Hello Antonis,
your reply was addressing the volume issue or the Pop that occurs while switching the FX on and off?

The volume issue is addressed,
the problem now is loud pops when switching the FX

[pinkjimiphoton]

have ya tried pulldown resistors? they don't just have to be at the input and/or output of boards. you can use 'em anywhere ya have a switch. i usually go bigger in that case, 2.2m-4.7m. works fine with high gain fuzz, so should work in a trem circuit, i'd imagine

[Kipper4]

Switch popping is invariably due to dc on the output of the previous effect or on the input.
Have you metered the inputs and outputs for dc? Or even the amp input?

The idea of the pull down resistor is to bleed off that dc to gnd quickly or slowly depending on the resistance.
This is not a cure all but it often helps.
Note that the size of the pull down resistance might affect the input impedance.

Hope you get it fixed soon.

[Kipper4]

If you use the search function, try. "popping"
Have a look at some previous answers.

[antonis]

your reply was addressing the volume issue or the Pop that occurs while switching the FX on and off?
The volume issue is addressed,
the problem now is loud pops when switching the FX

Obviously was addressing the volume issue..
(didn't read you've managed to addres it..) 

About popping, wire your switch for input grounded when FX off..

[ilcaccillo]

About popping, wire your switch for input grounded when FX off..

thanks, but I still have areally really loud popping when switching on/off.

there are the things I tried, nad didnt work:

- input grounded when off, pull down resistors at input and output
- pulldown resistor + current limiting resistors
- addressed the Led current with the scheme from AMZ
- changed the switch model/brand

nothing reduced the very Loud Pop

I don't really know what to do

[antonis]

Although your Output is already "seriously" grounded (via 10k resistor), try to wire your switch with In AND OUT grounded..

Or try to replace 10μF output cap with a non-polarized 1μF one (just for popping check purpose) and if that works let it be there..
(you'll raise HPF from 1.56 Hz to 16 Hz but, IMHO, it should be a "low price" anti-pop modification..)

[ilcaccillo]

About popping, wire your switch for input grounded when FX off..

thanks, but I still have areally really loud popping when switching on/off.

these are the things I tried, didnt work:

- input grounded when off, pull down resistors at input and output
- pulldown resistor + current limiting resistors
- addressed the Led current with the scheme from AMZ
- changed the switch model/brand

nothing reduced the very Loud Pop

I don't really know what to do