Rebote 2.5 momentary switching, and a noise problem.

[sfr]

I threw together a Rebote 2.5 over the last couple of days.

I rigged it up with a toggle and an extra (momentary) footswitch, so with the toggle flipped, the input to the delay is broken until the momentary footswitch is pressed.  (Kind of like mentioned in this thread)

I broke the connection at the first 12K resistor immediatly after the 1?F cap coming off pin 7 of the TL072.  (Actually, I lifted the the 12k resistor, attached it to common lug on the switch, and ran the connection wires for the switching off that resistor and the lugs back to the pads for the resistor on the board)

The only thing that's confusing me, is that when I use the toggle to activate the momentary mode, it seems to alter the number of repeats.  That is, with the knob almost dimed, so I'm getting *almost* infinite repeats, if I move to the momentary mode, the repeats are now infinite.  Or what might be 1 and a half repeats in normal mode is two and a half repeats in momentary mode.  It just messes the adjustment range. (Holding down the momentary switch makes the number of repeats go back to what it was.) 

So I assume this a result of where I'm breaking the input connection, although I thought I had it right.   So where *should* I break the connection to make this work properly?  (Not that this is really a huge problem, it's just frustrating.)   Should I break the connection before the 12k?  (Perhaps do what I did but with the pads for the 1?F cap?)

Also, I'm noticing sort of wierd noise along with my repeats - it's sort of like white noise that only comes in with my repeats - that is, if I play percussively, you'll hear the static-y white noise come in with each repeat.  This noise was there before I did the switching mod described above, btw.) This is boxed up and grounded properly. Interestingly enough, my old Rebote 2 delay does the same thing, and I never noticed until now, A/Bing the two.  Given that I've *never* noticed this before, and I've been using the Rebote 2 for quite some time, I think it may be my practice amp I'm using here at the house; it seems to amplify a high end way above what it needs to.  (come to think of it, this amp has picked up other wierd noises with other pedals that I don't get with my regular amp)  Has anyone else noticed this noise with their rebote builds?  I might be able to make a sound clip later if my explanation of it doesn't make sense?  It's not an incredibly bothersome noise, but it's there.

All in all, I love this delay, and probably like this "flavor" slightly better than the Rebote 2 right now, although I'll bring it to practice tonight and see what it sounds like through my "real" rig.

[sfr]

Answering my own question...  (My ride bailed on me so I ended up at the house with time to tinker some)  I replaced the 12k resistor and tapped the momentary switch off of the 1µF cap before it, and everything works perfect.  Just in case anyone wants to do the same thing and was interested.

Still curious about the noise, haven't been able to track it down yet.  Tried it in a different amp (took a walk down to my friend who works at the guitar shop) and it was more noticable on the longer delay settings, so I guess it's just inherent in the chip?

[343 Salty Beans]

i think your link is broken....at least for me.

Glad you answered your own question...dang, now I'm thinking of doing that mod for mine.

PS: The rebote is reputed to get dirtier as the repeats continue. If it's a trebly problem, you can always up the cap that cuts highs with each repeat (I think it's the 560pf?), or simply up the output cap. Of course, that means less treble for your guitar in general.

[sfr]

Well, I take back my second post - I guess I just didn't notice it with the repeat volume down, but playing it some more, I *still* have the same problem, switching to "momentary" mode changes to repeat level.  I guess I need to break the input to the delay somewhere else?  I don't know where.

Yeah, I see that link is broken - a " got appended to the begining and end; I forget that the bulletinboard code is not the same as HTML - the link to that thread is this:

http://www.diystompboxes.com/smfforum/index.php?topic=34587.0

Yeah, I'm thinking of upping the cap in the filter section - the noise is much louder before the filter, so that's cutting some of it, I guess? 

With long delay and many repeats, it does get "dirty" as time goes on, but this is almost something different.  I'll have to see if I can post a sound clip.

[343 Salty Beans]

An unlikely idea, but maybe your power/input/output wires are running to close to the PT2399. I've heard warnings about getting a lot of noise. Perhaps the repeating section of the PT2399 is the only part picking up noise, so each repeat is picking up a little more of the noise from those lines. If you have ferrite beads lying around, try slipping them on  each of those wires. It couldn't hurt 

[searoad]

i did it on my rebote2 recently. works nicely!!
i think the switch should avoid being connected to the capacity or it will cause some pop.
dont know where the trace shoule be broken on rebote2.5.
never find a problem with repeat issue.(however its useful to set the repeat knob min)
rebote is a little noisy but i dont hear a white noise there.

i also add the FXloop and have found lots of interesting effects.
some like:puting the nurse quark in loop and using the momentary switch to control delays.
very similar to a rocker kind of wah wah!
or set the repeat knob higher to get some violin-like sound.(it need some practice )
very worthful to mod!

[343 Salty Beans]

searoad: where did you find the FX loop mod? Is it the same one that was posted for the AD-2380 delay?  If so, how/where did you splice it in?

[searoad]

i think u ask how moosapotamus's idea using on rebote delay right?
i tried and split the connection after the pin7 of opamp.
(i thought its the path of the audio input to the mixer stage which Mr.Hammer mentioned)
(i also tried but FXloop doesnt work on the connection between the audio input and the PT2399)
lift 22k resistor and 1uf cap then wire something like this:
http://www.diystompboxes.com/smfforum/index.php?topic=44831.msg326675#msg326675
(use clips to test before soldering on the switch will save lots of time )
i remembered 'idiot savant' also posted an article to how to avoid the pop.

i wired it at the volume knob after all/(i think its the same keeley modded DD3)
put the FXloop before signal going to delay and filters will drop a little volume, espically for distortion pedals.
but its good for modulation pedals.
i didnt have enough space to put another toggle switch so i chose another way to mod it.
u can try both to suit ur taste!

sorry for my poor english if it let u misunderstood

[sfr]

Just an addendum here - I was playing around with this pedal some more, trying to solve my problem.  The problem being that breaking the input to the delay around the 1µF cap and 12k resistor coming off pin 7 of the TL072 to allow use of a momentary switch to only "feed" the delay input with signal while the switch was pressed down, while still allowing repeats already occuring to trail off would mess with the "repeats" setting - in some cases creating self-oscillation with the repeats knob halfway, whereas normally I wasn't getting oscillation at all.

I was messing with it, and it was fun because I could get the pedal oscillating and then step on the switch (as if to "feed" more delay into the chain) and it would stop the oscillation (setting the "repeats" back to where it should be.)  Well, I noticed a couple of things - that more that just upping the amount of repeats, breaking that connection also upped the volume of the repeats, and in some cases added a bit of distortion.

I went back and looked at the circuit again - breaking the input around the 12K resistor/1µF cap also effectively raises the gain on the second opamp in the circuit (the one integrated into the PT2399 with an inverting input at pin 16 and an output at pin 15) because that resistor is now "hanging" only connected on one end.  (The gain of the opamp being set by the ratio of the 47K feedback resistor and the three 12k resistors on the way into pin 16, and I just removed one of those 12k resistors)  I guessed all I need to do is use the other side of my momentary switch to tie that open end of the 12k resistor to ground. (the switch is one of the x-wing ones with a pair of NC and NO connections, each set sharing a common middle lug - a momentary DPDT.)

A quick experiment confirms that this keeps the levels the same. 

There may be some popping - I'm uncertain at this point, I'm using a wire and alligator clips to make that ground connection, and doing it manually (play a little into the delay, release the momentary switch, then reach in and ground that resistor with the clips) since I have the wrong wire going to the common lug right now, preventing me from just attaching the wire to the NC side of the momentary switch.  I'll see what happens when I have it wired up to the switch proper.

So I feel pretty silly that this never occured to me - ground the input, don't just break it.  Seems like common sense now that I look at it.

Looking back at the schematic, making the break to the input line where I am, I wonder whether it's better to break before or after that 1µF capacitor - that is, should I leave it attached to pin 7 of the TL072 and break after it, or should I leave it connected to the first 12K resistor feeding into pin 16 (inverting opamp input) of the PT2399 and break the input line before it?  I'm not sure it matters?

[Wounded Paw]

I'm gonna try this on a Rebote 2.5 I'm building for our guitar player.  I posted here -> http://www.diystompboxes.com/smfforum/index.php?topic=54263.0
with a quick schematic and my switching plan.  I think I have it right.

[Fp-www.Tonepad.com]

Good stuff!

[Wounded Paw]

i'm gonna post my schematic again here cuz I want to build this tomorrow and wouldn't mind some confirmation that I've got things correct.  The schematic is just the section after leaving pin 7 of IC2b and after splitting the clean signal away, up to the first 12K resistor of three on the way to pin 16 of the PT2399, ie this whole thing would replace the 1uF cap that's there now.



so in the first position for the DPDT toggle the delay send is on until the momentary is pressed and in the second position the delay send is off until the momentary is pressed.  I've incorporated what I interpreted to be R.G.'s advice on avoiding any pops when switching.

Does it look right?

[Barcode80]

why would you put the switch in-circuit? why not run your switch assembly right on the input?

[Wounded Paw]

Because that would change the output level.  Putting the switch there only interrupts the send to the delay section.  Any previous delays would continue and the original signal would still be present so the output of the whole pedal would not change.

[Wounded Paw]

Well this is gonna have to wait as I can't seem to get a DPDT momentary foot switch around here.  Got one on order from Small Bear.

So, do I have this right?  Will my schematic avoid popping and do what I want it to?