Re: Repeater noise problem

[Kim Flint <kflint@loopers-delight.com>]

>From: "sukhjindersandhu" <sukhjindersandhu@home.com>
>
> > I'm wondering if any other repeater users have noticed a strange 
>wavering
> > of pitch when nothing is looped, but the phones or main outs are 
>cranked.
> > It's almost like a low oscillating tone. Again, i'm not playing 
>anything
> > through repeater but the noise level is very high. Could it be software
> > or hardware related? I've tried moving repeater away from other gear, 
>plus
> > all kinds of level changing and checking but the noise persists. Is 
>there
>a
> > bypass option someone can suggest?


I was noticing this too, and wondered if it was just me so I checked back 
a 
few days and saw these posts where others had the same noise. What baffled 
me though, is it is on the direct audio through Repeater, even when there 
is no loop recorded? I guess I would expect the direct audio to be much 
more transparent? I can see the loop audio being noisy since it has to go 
through digital convertors and dsp algorithms and such. (and that's the 
sort of noise it sounds like to me.) But does the direct audio go through 
that path too? If so, why?  I did notice the noise seems to somewhat 
relate 
to what is on the display, and I guess Damon had said that before. When I 
optimize the gains it isn't very noticeable, so it really isn't that big 
of 
a deal most of the time but you can hear it when the levels are up loud.

I was also looking at the audio routing diagrams in the back of the manual 
and saw the direct audio path through Repeater actually does appear to go 
through the digital convertors and through the DSP. Is that correct? The 
direct audio path isn't analog? (shh, don't let any guitar purists know 
about that....:-)  I wondered if I could hear any difference in the direct 
sound through the Repeater so I set up a parallel path through the mixer 
and ran some drums and guitar through it. I didn't really notice any audio 
difference, but I'm not exactly golden-eared and didn't do any real 
serious 
tests. But it's probably good enough for me.

However, I was quite surprised to notice a delay on direct audio through 
the repeater when I played the parallel path and repeater direct path 
together. It wasn't just a phase error sort of thing either, but enough to 
sound like a fast slap-back delay when mixed with the parallel path. 
Pretty 
obvious on the percussion sounds I ran through it, definite flams. Playing 
guitar through it I could feel there was a delay, but only when I really 
concentrated on it and compared against playing direct to the amp. kind of 
like playing guitar synth, a bit sluggish but you can compensate for it. 
So 
I guess there is quite a bit of buffering going on in the dsp path, even 
on 
direct audio? I had a vague hope that maybe this delay would offset the 
midi sync problems but no luck there. :-) Maybe all that buffering is what 
causes the midi sync problems?

kim


______________________________________________________________________
Kim Flint                     | Looper's Delight
kflint@loopers-delight.com    | http://www.loopers-delight.com