MADBOX mixer splitter problem

[damianoc]

Hi guys !
Recently I built up a madbox splitter mixer but unluckly it isn't working properly.
The splitter section produce a lot of clipping and a big loss of frequencies , I'm using it with my music man stingray five and with a onespot power supply.
The transistors in the circuit seems to be fine and everything is built up in the right way.
To me it seems like an impedance issue but I'm not sosure about that...
Any advices or tips for trying to solve that problem?
Thanks so much for you help.

keep up making sick DIY pedals.
cheers from italy

[WormBoy]

Are you talking about the TH Custom project? For bass, you might want to increase the value of the 220n caps; that may cure the loss of (low) frequencies, but that does not explain the clipping you experience. Are you using an active instrument? If it puts out quite a hefty signal voltage it might send the ICs into overdrive. With a passive instrument (or volume on the bass turned down) there should be no clipping, and if there is, there's something wrong (I would then start by checking whether the reference voltage VR is indeed 4.5V.

If the ICs are clipping due to a high input signal voltage, you could try a higher supply voltage. Make sure you check the max. allowed voltage on the filter caps C9 and C10 (which sees half the supply voltage) and make sure you stay well below their specified max. voltage! Alternatively, you could try rail-to-rail opamps that clip a bit later (but you won't gain that much headroom that way, I guess).