# Ridiculously loud output volume with Roboto



## jpier2012 (Mar 24, 2022)

Hello!

I just completed the Roboto. It kind of works, I'm getting lots of crazy sounds, reminiscent of a ring modulator more than anything, but the output volume is absurdly high and it doesn't sound much like the demo videos. I can only the volume up a hair past 0 before it gets unbearably loud. I turned the gain trimpot all the way down with little effect. I also double checked that I have the correct pots and resistors R8 - R11 along the output path. I even replaced the TL072. No dice.

I'm an experienced builder, and this is a relatively simple build, so I'm kind of surprised there's an issue. My first thought is that I got a bad HT8950, but it looks to be in good condition and I'm still getting a signal coming through.

Has anyone else experienced this? Or know of a reputable source for an HT8950?

Thank you


----------



## jesuscrisp (Mar 25, 2022)

Post pictures please. 

Otherwise double check all your values, maybe something is off there


----------



## jpier2012 (Mar 25, 2022)

Woops

Just checked the voltages on the regulator... outputting 3.28V, so we're good there. Confirmed that's what's feeding the TL072 non-inverting inputs. Even if a cap value is off, idk how that would so greatly affect the output volume. I also measured the volume pot before installing, so I don't think it's that. Seems like it's gotta be the HT8950 chip.

Edit: It's in a box with 2 other pedals, that's why the jacks aren't grounded to the board, they're grounded to the sister pedals.


----------



## mdc (Mar 25, 2022)

Maybe an obvious thing, but are you using an audio taper pot for the volume?


----------



## jpier2012 (Mar 25, 2022)

mdc said:


> Maybe an obvious thing, but are you using an audio taper pot for the volume?


Yes, at least it's labeled as A100k... I'm not sure how often pot tapers are mislabeled, but that might be it? lol


----------



## BuddytheReow (Mar 25, 2022)

I would cleanup those solder joints with some IPA. You also look like there’s too much solder on there


----------



## Dan M (Mar 25, 2022)

I would color code check all of the resistors.  Maybe you installed a 47R instead of a 47k, etc.  I’ve done that before.

I’ve never found a bad component.  I’m sure it can happen, but in my case it’s always been bad soldering or incorrect component install.


----------



## Coda (Mar 25, 2022)

Can you swap out IC2?…


----------



## Dan M (Mar 25, 2022)

Is R12 brown-black-black-red?  I can't see it well enough in the picture, it's the bottom one on the right.


----------



## PJS (Mar 27, 2022)

Have you got an audio probe?  Could be useful to probe the circuit and work out where the volume increase happens


----------



## jpier2012 (Mar 27, 2022)

Hey everyone, thanks so much for the replies. I will investigate further as soon as I get a chance, since it's such a simple circuit I will end up reviewing every component individually. I also agree that I could probably use a bit less solder and may as well clean the board to see if I made any errors. 

I already tried swapping out the TL072 any it didn't change anything.

I did check the voltages on the regulator and ICs and they were correct, but I agree I will probably need the probe to identify where the boost actually occurs.


----------

