number 60 - rebote 2.5

[lowstar]

hi everybody,

circuit number 60 was the rebote delay 2.5.
fired up right away but the noise accompanying longer delays mentioned by other builders is pretty annoying.
on shorter delays it´s not so prominent but i rather want delay than slapback...guess i´m gonna take it apart again to salvage the more expensive parts like caps.

cheers,
lowstar

[sfr]

Honestly, I've seen mention of this quite a bit (and I've mentioned it myself!) and I have to say one again that while it can be annoying when you notice it playing alone, it is really unnoticable playing in any sort of band context.  I think we've all blown it out of proportion.  In fact, I really only find it annoying once I start noticing it - it's one of those things that once you pick up on it, it grates at you, but if you're really playing, you don't notice it at all, because you're focused on the music!  People who have seen me perform have said the same thing - if you're music is moving, they aren't noticing that annoying noise at all because they're listening to the music - if you tell them about the noise and they notice it, then it gets to them because they continue to notice it.

I've also notice some of my junkier amps don't reproduce the annoying noise, and it is also absent when I run my LPB after my Rebote.  If you put a graphic EQ after the Rebote (or you have on on your amp) you should be able to dial the noise out fairly easily w/o effecting your guitar tone too awful much.

I increased some cap values in one of the Rebote 2.5's I built, and it effectively cut out that noise except at the longest settings of delay (I have a switch on mine that adds resistance to the delay rate, and effectively doubles it, at the expense of sounding kind of "lo-fi" and upping the noise that accompanies the repeats.)  This change does change the tone of the repeats slightly, making them "warmer" or "tone sucking" them, depending on your point of view.

I'm digging out that pedal to see which two I changed, and I'll posting that info in the other Rebote thread going on right now in a little bit.

[markm]

I still say, all of this noise issue is news to me as this was the first I have read anything about it and I have not noticed it myself however, I do only use mine for slapback.
I'll have to fire it up today and check it on longer delay times and see if I hear what you fellas are describing.

[lowstar]

try it with headphones and it will be easy to hear. it is like some white noise added to the repeats.
thru a guitar amp it is much less noticeable probably cause of the lack of highs that the speakers put out, but since i´m a bass player, our rigs usually have tweeters, and our di´d signals thru the p.a. carry lotsa highs, too (and i´d wanna use it for bass if i´m gonna box it up).

cheers,
lowstar

[markm]

try it with headphones and it will be easy to hear.

Well then, in that case I wouldn't be surprised to hear some noise at all. 
I don't have a method at this point to listen to my effects through a set of phones, I just have a BF Deluxe or Twin, or a Tweed Bassman.....It sounds good through those though.
Sorry I can't help. 

[Barcode80]

i've been looking at the perf layout, and i'm a little confused. the insulated wire runs are a little hard to make out, and the legend in the upper corner lists some runs that don't appear (e.g. c2 to grnd). a little help...

also, i'm not familiar with that transistor, what other transistors have worked for you guys. i have a supply of most of the "gen purpose silicon" values.

[oldrocker]

Well when I first built mine I didn't hear any noise either and believe me I was listening close for it.  I had headphones on.  It wasn't until I resoldered a cold solder joint, that's when it showed up.  So I don't know what happened.  I wish I could find what I did different because I was heating up many solder joints and I don't remember what I did.  But the bottom line is it was clean before that.

[oldrocker]

Has anyone tried making the PT2399 Delay circuit that is on the datasheet.   Does that suffer from the same noise problem?  I'll be building it anyway since I've been wanting to try it when I saw the layout on Geo.  Although the PT-80 sounds interesting too.

[Barcode80]

hey guys, anyone notice my questions?

[oldrocker]

Hi barcode,  I don't understand your question about insulated runs or transistors since the Rebote doesn't use any transistors.  And the subject matter of this thread is noise caused by the delay effects.  Your question seemed a little off topic.  I know I'm guilty of getting off topic myself at times so no offense intended.  You might start a new subject with more details and I'm sure you'll get more responses.  Sorry I can't help.

[Paul Perry (Frostwave)]

The technology used in those PT chips isn't "low noise". But having said that, in my opinion, it's "close enough for rock & roll". Maybe not studio work.
Maybe if you are using it with bass, a low pass filter on the out would help. (or, better, just after the chip). And, like all noisy technology - including the BBD - compression before the unit & expansion after it will help. And it is essential to have max signal level going to it (below clipping, of course).

[Barcode80]

oldrocker, check out this rebote 2.5 layout:

http://aronnelson.com/gallery/albums/rebote25/Rebote_2_5.gif

see the trannie?

[sfr]

The transistor there is a 78L05, a voltage regulator.  (I believe it's a 5V one?)  Can't really sub it with anything else except another equal voltage regulator.  Small Bear carries them, I believe Radio Shack might have something that will work as well. 

[oldrocker]

Sorry barcode, yeah that 5v voltage regulator sure does look like a transistor.  But it regulates voltage only.  I can see where that can be confusing.  As for the unsulated wire runs that is also confusing but if you get the schematic and study it along with the layout it will be more clear.  That's how I figured it out.  Go to tonepad.com and print the schematic and lay it side by side with the layout and write on the layout the corresponding components to match the schem and it might clear up the insulated wire confusion.

[puretube]

anyone knows, or has measured the max input voltage before clipping of this chip?
("headroom issue?")

maybe some lowpass filtering in the feedback-path can help lowering the noise?

[Sweetalk]

Hi!... I build a rebote 2.5 and noticed the noise in the repeats... I been experimenting a little bit and found out that running it at 12 or 15v the repeats are much cleaner and better sounding... The noise it's still there, but improves the overall sound. Carefull with this... Op-amps has a 18v max voltage supply, and look the electrolytics to see the voltage, with 25v has to be fine.

I hope this helps a little.

[Barcode80]

makes sense, that's probably why my old DOD 585 runs on 18v instead of 9.

[puretube]

I was rather thinking of sending higher signal-voltage into the chip...

[Barcode80]

but the logic does follow, much like getting more clean headroom by running a boost at 18v.

[Sweetalk]

I tried at 15v max because I had a 16v electrolytic and I was LAZY to change it to a 25 or 50v one..., you can try with a 7660 voltage doubler to run it with 9v.

Another question, maybe off topic : anyone experimented that a 9v battery doesn't last nothing?... anyone measured the consumption of the rebote?, I think it's very high....