Adjusting Zero Point SDX input gain for line level

[Oscilloclast]

So I built the Zero Point SDX and I really like it.  It sounds great when I put guitar through it but when I put a synth through there is a noticeable amount of distortion on the output.  I'm wondering that if I lower the input gain into the delay if this may help clean up the signal a bit (I'm well aware of the lofi-ness of the PT chips).  Could anyone tell me which resistors I need to change on the input OP AMP to lower the input level?  Much appreciated!

[midwayfair]

Almost nothing about the ZP would be appropriate for line-level signals, which from a synth are often as much as 12V/-12V peak to peak. First you'd have to knock it down to 1/4 of that just to avoid overdriving the dry path (which runs on 9V), and it has to be under 2.5V peak to peak to avoid overdriving the PT2399. You can't run the pedal on higher voltage because you'll melt the 5V regulator, and you can't get more than 6V (absolute max) to the pt2399 in any case.

Essentially the only thing you can do is put a volume control on the input. This will knock down the volume of the synth, but of course it's also going to massively reduce the volume of your signal when you turn on the delay.

[alanp]

It could be a good little project to work up a synth module to take synth level signal, bust it down to guitar FX level, and then take the return signal and boost it back up to the synth level. Then you could use it with multiple FX.

[Oscilloclast]

Opps.. I stated my question wrong.  What I meant to say was that I want to run a keyboard (with line level out 1-2volts?) through the delay not a modular synth (10v plus).  I'm assuming that the delay is designed to accept a guitar signal which is much lower voltage then line level.  I think it may just be a case of having to lower the gain on the input opamp but I'm just not sure which resistors to change.  Sorry for the confusion.

[midwayfair]

Opps.. I stated my question wrong.  What I meant to say was that I want to run a keyboard (with line level out 1-2volts?) through the delay not a modular synth (10v plus).  I'm assuming that the delay is designed to accept a guitar signal which is much lower voltage then line level.  I think it may just be a case of having to lower the gain on the input opamp but I'm just not sure which resistors to change.  Sorry for the confusion.

Is there distortion when it's 100% dry?

A 9V circuit should normally be able to handle 1-2V of input; humbucker guitars get that high all the time. The answer will be different if it's present in the dry path or just the delay.

[pickdropper]

I knocked the gain down on mine, but I did it on the second amplification stage (R5).  It wasn't because of distortion, but because the pedal was above unity, which I didn't want.

[Oscilloclast]

There is no distortion on the 100% dry signal, just on the delayed signal.  I have a feeling that the delay chips are being slightly overdriven (which is causing the distortion) so If I could lower the gain on the input signal I may be able to lower the distortion.

Thanks!