HELP with DIY JHS AT @ - lack of low end/bass

[Gregst98]

Hi, I recently built a JHS andy timmons OD pedal (from jedspeds kit).

I've never played a real one but I find it lacks a bit of bass and low end. It's not really thin sounding, but I feel like a little something is missing. Comparing it to my full drive 3, it definalty lacks a bit of bass - maybe its supposed to! The only setting I like on the @ is the 100w mode. Its the only with some low end to it. And no matter how much I play with the EQ and air pots, its still a bit thin.

Since this build I've done lots opf reasearch to building pedals not from kits (got some madbean pcbs on order) and found that using differnt capactiors such as ceramics might filter out some low end. Is this the likely cause of my problem? and if so, which caps should I replace, and what with?

Any help would be greatly appreciated.

[mjcyates]

I built the same circuit using the pedalpcb board and it does not seem to suffer a lack of bass. I compared the two bill of materials and they were the same. The schematics on the jedpeds build that you did do not totally match the bill of materials. There is a difference in R3 (1m vs 1k), C2 (1n vs 22n) and C8 (22n vs 1uf). Not sure what you populated on your board but you may want to double check those components.

[JackSkellington]

I would like to built it, too. Check again if you mismatched some parts.
R3 is the BIAS resistor, I don't know what really happend if you change its value, but in this case even the C2 cap value is different. Maybe later you could try some swap them.

[Gregst98]

great thanks, that's really helpful. I'll check what he gave - I've built a few of his kits and the problem is he sometimes just gives rough approximations of the values of parts.

I noticed comparing to pedfal PCB, mine has a 4001, where as PEDALPCB has 1n5817. Also the ICs are 4580D vs a LM833. Could either of those be the culprit?

[JackSkellington]

The diode probably doesn't make any difference, because that is just a polarity protection of the supply, and it cut a little the power.
The IC could make a bit difference, but not so much, I think.