Rebote 2.5 delay "white noise" issues

[hooya]

Just built a Rebote 2.5 delay. It sounds pretty darn good, although I find that when I engage there's a bit of a whilte-noise like background hiss to it. The signal is clear and clean in general. Delays get pretty modulated/distorted at longer times as about how I'd expect it based on what I've read. But nobody has complained about just straight up noise in the background. It's very quiet, and I'm using a headphone amp to test so it's a very sensitive environment, maybe most people just don't notice it through their amp?

Anyway, wondering what kind of component changes I could make to make this delay a little more Hi-Fi and actually less analog sounding. Something in that might help eliminate noise as well, since I figure it's probably the noise of the delay signal of silence when I'm not playing, if that makes sense.

[jkokura]

If you built it using a stock Tonepad board, chances are high that many of your large caps are electrolytic. It may be that using Film caps for the 1uF caps would lower your noise potentially.

Also, the type of resistors might make a difference as well. If you used Carbon Film resistors, there's potential that using Metal film would lower your noise.

Finally, some chips are noisier than others. Particularly the PT2399, and if you used something other than TL072 chips for the dual op amps. Changing your chips may lower your noise.

Jacob

[hooya]

I used the same caps that I use for everything, I can see if I have some nicer caps for the 1uF ones, but I don't think so. But those would be the ones to change? And yeah, carbon comp resistors all the way. Are particular resistors in the circuit going to change the sound more than others? I'm not about to go part swapping all over the place at this time I don't think unless there is a sure thing there.

I etched my own board and used my own part supply...

I did use the TL072 and PT2399 chips. I have a couple extras of both, so I can try swapping chips to see if the helps at all. Would there be "better" options for the op-amp in this circuit? I hear people complain about the TL072 all the time and others saying that they're full of it, but maybe in this circuit it really does matter? I don't think I have any 4558 chips left anywhere.

[.Mike]

Have a look over here to see if it might help with the noise: How to "Sshhhut" up a PT2399 once and for all!

You're not going to make it much more hi-fi and less analog sounding. The PT-2399 requires filtering to reduce noise, and that filtering, along with the chip's limited bandwidth, adds to the analog sound.

If you want crystal clear repeats, you're probably looking at a Spin FV-1, or a commercial delay.

Mike

[hooya]

That actually looks very much to be related what I'm hearing. I'll give it a try and see what happens for me. I'll report back later tonight, in that thread too.

Thanks!