Trouble with Emerson Paramount from Tagboard Effects layout

[OasisMcFly]

Hi All,

I am having a weird issue with my Emerson Paramount clone made from the layout on Tagboard Effects.

http://tagboardeffects.blogspot.com/2014/02/emerson-custom-guitars-paramount.html

Everything on the build seems to work great, except for the tone knob. It does control tone as expected, but it also seems to be affecting the gain as well. Setting it to a more trebly setting cleans up the gain, and conversely, setting it to a bassy setting increases the gain and makes it more distorted. On the bassy setting, it also seems to give a noticeable volume boost, though I can't be certain if it is an actual volume increase, or if I am just perceiving more volume as the gain increases.

I have been over my build multiple times and everything is wired as indicated. I checked for solder bridges as well, but I didn't find any. At this point, I am not sure what else to look for. Could it be a bad component, and if so, what is my likely culprit?

Any help would be appreciated.

[midwayfair]

This is normal. Look at the schematic - the tone control is in front of the gain stage, controlling the amount of bass in the signal. If you cut bass, you have less signal overall. Turn up the bass and you get more signal, and more BIG signal from all those fundamental notes, which results in more saturation and more total signal.

I'm willing to bet that there is also a slightly "dead" area in the center of the tone control.

There are a bunch of things to dislike about this design ... the gain control is a large resistive attenuator at the input and affects the highs, and the tone control they slapped on there also adds to the input impedance when it's anywhere but fully "on" or fully "off", so in the center of the pot, it's like having the gain control turned down halfway. It would have been much better to just put, say, a 470K from the base to ground and then make the tone control a 1M variable resistor in series with the bigger capacitor. The gain control is forgivable, but the tone control is, IMO, just poorly thought-out.

[OasisMcFly]

Wow, that was the answer I was expecting, but it definitely makes sense. Thanks for the info. I'm glad to know it wasn't something I had done horribly wrong, but that still leaves me a bit disappointed. I had high hopes for this pedal, based off some videos reviews. Also, I was quite surprised to see that it had such a low part count. The only question remaining for me is how so many people recommended this pedal and never once mentioned that the tone control affected the bass in this manner...

[midwayfair]

Wow, that was the answer I was expecting, but it definitely makes sense. Thanks for the info. I'm glad to know it wasn't something I had done horribly wrong, but that still leaves me a bit disappointed. I had high hopes for this pedal, based off some videos reviews. Also, I was quite surprised to see that it had such a low part count. The only question remaining for me is how so many people recommended this pedal and never once mentioned that the tone control affected the bass in this manner...

Well, luckily you're building it yourself, so there's no reason to use their design if you don't like it. Blending the bass at the input to control saturation is common, I'm just taking issue with how they chose to implement it. What do you want the tone control to do instead?

[OasisMcFly]

I generally try set the tone knobs to be as tone neutral as possible, but I often switch between my Tele and my Les Paul during performances. So I do end up adjusting the tone knob differently for each. I usually mark the settings for each guitar on the pedal with a bit of tape. I had originally intended to use this pedal as part of a stack with a couple of other overdrives, set the volume for unity and set the gain for a mild crunch.

I am also making a clone of the Fairfield Circuitry Barbershop to serve this same purpose. I couldn't decide which pedal I wanted, so I decided I would make both and A/B them so I could see which one played best with my other pedals. I had all the parts for this Paramount drive already, so I went ahead and built it while I wait on the other parts to ship from Mouser.