More volume from a tube screamer circuit

[idsnowdog]

I recently bought a Kokko Overdrive pedal and it's nearly identical sounding to a Tube Screamer. It's good for adding a bit of dirt to an already dirty amp but it isn't very loud when compared to a newer design like a Joyo Ultimate Drive. Would replacing the 100K level pot with a 250K level pot increase output? Because otherwise the disparity in volume between the two is so drastic that they basically don't belong together on the same pedal board.

 

[GuitarStv]

How much room in the chasis is there? Boost circuits are easy and small, you could stick something like this in with a mini-pot to fine tune how much boost you want. Just put it after the tubescreamer circuit and since it'll always be on you can simplify it by removing the 1M pulldown resistor:

 

[Mincer]

Yeah, TS-type pedals aren't that loud. And if going into an already distorted amp, they get more compressed not louder. I don't even know if a boost would help- it would depend on how much preamp gain there already is.

 

[idsnowdog]

How much room in the chasis is there? Boost circuits are easy and small, you could stick something like this in with a mini-pot to fine tune how much boost you want. Just put it after the tubescreamer circuit and since it'll always be on you can simplify it by removing the 1M pulldown resistor:

For the price of a LPB1 I would opt for the Kokko Booster. It has volume, bass, treble, and seems to be more transparent.

 

[GuitarStv]

For the price of a LPB1 I would opt for the Kokko Booster. It has volume, bass, treble, and seems to be more transparent.

It's about 10$ to build an LPB1 into the chassis of another pedal.

 

[idsnowdog]

It's about 10$ to build an LPB1 into the chassis of another pedal.

The Kokko pedals are mini's and the majority of components are SMD so they aren't easy to modify. About the only parts that are accessible are the pots. Not a bad idea though.

 

[GuitarStv]

The Kokko pedals are mini's and the majority of components are SMD so they aren't easy to modify. About the only parts that are accessible are the pots. Not a bad idea though.

Ah, I didn't realize that. Thought we were talking about a full sized pedal. Sorry.

 

[idsnowdog]

Here's a picture of the board. It has those tiny surface mounted component and it only has a 9v adapter because it's too small for a battery. It makes for a small and cheap pedal but I don't think you can do much for mods.

 

[ErikH]

It is the nature of overdrive circuits. Now, if is possible to get more volume by making the output stage hotter but that would require a rebias if the output transistor so as to not make it distort. Another way that is quick and easy is to remove the diodes or swap them out for LED’s. LED’s have a higher forward voltage so take more before they clip. SMT components are a pain but not impossible to work with.

 

[PFDarkside]

Is that already using LEDs for clipping? I’ll admit I’m not the best at identifying SMD parts, but the board says LED.

 

[ErikH]

Is that already using LEDs for clipping? I’ll admit I’m not the best at identifying SMD parts, but the board says LED.

You could be right there. The two components to the upper left of those labels with the + on the opposite sides look to be the LED clippers. I admit, I didn't look that closely at the board. Well, with that being the case, the output stage would be the place to fiddle with if you dare. Otherwise it is what it is.

 

[idsnowdog]

No they are silicon diodes. The LED is the on/off light. From what I have read capacitor C3 is a high-pass filter that cuts frequencies below 720hz. Which is part of the Tube Screamer's characteristic sound. However, part of the problem is when the Tube Screamer was designed pickups had less output so what sounds like a boost for a weak single coil sounds like a bottleneck for a high output active pickup. They say if you change the value of that capacitor you get more low frequencies which makes the pedal sound louder. Which would make sense if you are attenuating fewer frequencies the louder the signal will sound. But expanding the frequency range might alter the characteristics of the Tube Screamer sound.

http://www.muzique.com/lab/fatt.htm

 

[ErikH]

Well, yes and no to getting more volume from changing that cap. I've done the same with a Boss SD-1 (same circuit really) and the actual volume overall remained the same, just with more low end. More true volume overall is a different change.

LED2 is the on/off indicator. We're looking at LED1 and LED3. I bet if you play through it with it out of the enclosure, you might see the two components mentioned light up a little from clipping. Worth checking out. They are labeled as such.