Building the tap tempo tremolo

[LaceSensor]

Build and use an audio probe...

[lokki]

hi there, long time reader first time poster.

i built the tap tempo tremolo and i had issues with ticking, tried adjusting the 330p cap to 10n and all other suggestions, still ticking.

at some point i realised it was my amplifier that produced (most) of the ticking. if i put the tremolo into another amp it was quiet. (at very loud volumes you can hear a subtle click)
so to anyone struggling with clicks and ticking, try another amplifier, it might solve your problem.

so i now have a fully working tremolo, with clock output and metronome in!!! great. taylor thanks so much for a great pcb!

cheers

[therealfindo]

hi there, long time reader first time poster.

i built the tap tempo tremolo and i had issues with ticking, tried adjusting the 330p cap to 10n and all other suggestions, still ticking.

at some point i realised it was my amplifier that produced (most) of the ticking. if i put the tremolo into another amp it was quiet. (at very loud volumes you can hear a subtle click)
so to anyone struggling with clicks and ticking, try another amplifier, it might solve your problem.

so i now have a fully working tremolo, with clock output and metronome in!!! great. taylor thanks so much for a great pcb!

cheers

I had never noticed a click with my tube amp, but heard one when I tried it on my 1W punch SS amp.. which amps did you try it on?

[lokki]

i actually tried it with bass on a gallien krueger combo amp. the normal input did click, the return of the amp did not click. i then tried a fender twin, no click either...

i realised that the click on the gk amp is only when the led goes off, not when it goes on...

[9aul]

Hi, I've been trying to get this pedal working for some time, and having got my echo base recently working (which by the way is absolutely amazing, I think I'll be singing its praise and posting some pics soon) I've been filled with a new found drive to get my tap tempo up and running. So my problem was ticking (I seem to be in a similar boat as many other people, so sorry if you've heard it all before). When I say ticking, its not really a ticking but a variety of noises as the LED switches on and off which changes with the rate and wave shape etc. this is much louder than the actual guitar signal (which if you listen carefully you can hear and sounds quite nice).
ANYWAY, i have played around with the trim pots to no avail, ticking is always louder than guitar signal. I then replaced the 330p with a higher value cap as suggested, I've gone up to 22n (which is probably overkill but I just wana get this ticking out my head). this didnt change a thing. I've also replaced the opto (maybe a slight reduction but it was still louder than the guitar). These are the values I had for the chips:

I know this post is already dragging on, but sorry I'm not going to stop there.
So I went back to this pedal with my 3rd NSL-32 and replaced it. While I was at it I thought id re wire the jack and power so they switch the power on/off (like so http://www.beavisaudio.com/techpages/PedalPower/ )  , I also just used the ground tab for grounding the in jack (which is also linked the the ground of the out jack) since I had been using the LED -ve as a ground when fault finding which I've since read is a no no, especially for ticking. anyway I plugged in to test and now I get distortion! like a fuzz pedal.. the trem is working behind this and ticking is less (perhaps something I can even tame) but first I'd like to address the fuzz issue. Ive read this is probably something about bias but I'm not quite sure how to tackle it. Any suggestions would be much appreciated. Here are the new values since adding the new NSL and change of wiring:


Thanks to anyone can be bothered to read this essay, and a bigger thanks to any suggestions.

[9aul]

Also I cant seem to find the pic of the new bypass wiring that Taylor suggested and others have referred to

The LED does flash with the tempo already.

The bypass wiring in the PDF has kind of been replaced by the diagram in this thread:

http://www.diystompboxes.com/smfforum/index.php?topic=84020.msg713301#msg713301

Do you need some special glasses to see this or has it disappeared?
And could this be the answer to all my ticking worries? 

[Taylor]

For me, debugging with an audio probe has always been easier than looking at DC voltages. The audio path of this circuit is very simple, so you should be able to trace from input to output to see where things go awry. Since your LED is flashing and presumably responding to the pots, most of the circuit is working properly.

Since you're now getting distortion, this could be because you have the gain trim for the last opamp cranked up very high, so I'd revisit the trimpots now that you have audio.

The picture that you're not seeing doesn't change anything when the pedal is on. It grounds the LFO signal when in bypass. Ideally I should find that picture or reproduce it and add it to the documentation on the site. The day job is taking up all of my time right now but I will try to get to it! Feel free to bug me via email if I haven't gotten around to it in a week or two. 

[9aul]

Thanks Taylor. I'll check tonight but I don't think I was getting any ticking In bypass, so I guess Id probably be OK with the standard switch wiring.
Last time I checked with an audio probe, I was getting ticking throughout the whole circuit accept right at the beginning (it gets past the 1u cap and then when it gets to the op amp  only really pin 1 gets a clean signal, the rest have a very loud pulsing sound. The 0V side of R10 also made the pulsing sound.) This was last time I checked and I haven't checked since changing the opto and getting distortion. I'll get onto that and see what I can find. It may help with pinning down this distortion ,as I fiddled around with the gain trim and just got a quieter distorted signal and didn't get rid of the fuzz, it may be something else that i could find with a probe.

[p_wats]

Just wanted to say that I finally boxed my Tap Tempo Tremolo board up (after ordering it years ago!) and it's awesome. I now have at least 2 friends who want one as well...Great boards, as always!

[9aul]

Just found where the fuzz was coming from! (I've only just got round to actually looking at it). Couldn't work out where it was with the audio probe but then as I was going through I noticed one of the opto legs was touching a leg of a trim pot. Sorted that out and that sorted the fuzz out. Now its working pretty good. Ticking is still there most of it can be removed using the trim pots  (its not huge but still potentially a problem at higher volumes). Since I've already replaced the 330p with a 22n I think I'll go back and try the other two optos I have kicking about (I think I hastily changed these when the problem was else where). I think I'm well on the way to getting this one sorted.  One problem I have noticed however it that with when I change the wave form pot there is a point where I just get LED flashing (a quite harsh on and off) but absolutely no signal (just ticking), is this just in between switching wave forms? either side of this point all is fine. This is something I can live with, but I was just wondering if this is normal or if I should consider replacing the pot or something like that.
Thanks for all the help so far.

[Taylor]

My guess is that you have the wave distort all the way to one side so the square waveform has 1% duty cycle. Because of the slow speed of the opto it will never turn on this way. While getting used to the pedal try keeping wave distort in the middle until you understand its function.

[9aul]

Great, that's easy to solve! thanks for the info Taylor.

[threepwood]

Hey there

After ballsing up my first attempt, I'm having another go at building this circuit.

I've decided to wire the internal volume trimmer as an external volume pot. Just wondering how to go about this. The build doc says to use a 25K A pot but doesn't say how to connect it. Do the trimmer's PCB pads correspond to a pots lugs as I've numbered below or have I mixed things up?



Thanks in advance.

[Taylor]

That will work but it might work backwards. I get confused with the 1 2 3 numbering as I've seen people use it differently (are we looking at the back of the pot when counting or the front? Lugs pointing up or down?).

On the bottom of the board you should see that two of the trimpot leads are connected in the PCB. These two should go to the middle and right lugs when the pot shaft is pointing towards you, lugs pointing towards your feet. You can even just wire from the center pad to the center lug and connect a short wire from right lug to center lug. The other connection goes to the left lug of the pot.

If that's still confusing, short answer is to try it like you wrote it. If backwards, swap wires.

[threepwood]

That will work but it might work backwards. I get confused with the 1 2 3 numbering as I've seen people use it differently (are we looking at the back of the pot when counting or the front? Lugs pointing up or down?).

On the bottom of the board you should see that two of the trimpot leads are connected in the PCB. These two should go to the middle and right lugs when the pot shaft is pointing towards you, lugs pointing towards your feet. You can even just wire from the center pad to the center lug and connect a short wire from right lug to center lug. The other connection goes to the left lug of the pot.

If that's still confusing, short answer is to try it like you wrote it. If backwards, swap wires.

Thanks Taylor. That's great.

One more question.

I know the other two trimmers on the board can be 10k or 22k. Will 25k also work or is that too large? I only ask as I have a couple of 25k's spare and so won't have to order any in if they will do the trick.

Thanks again.

[Taylor]

25k is fine. The "gain" trimpot is a variable resistor in the feedback loop of the last opamp stage. In this case, larger resistance equals more gain. So, with a bigger pot value you'll be able to boost the gain higher at maximum. Things will distort if you amplify too much of course.

[threepwood]

Cheers Taylor

Finally got round to putting it together.

I wasn't getting any effected signal so poked around with my audio probe and found that the wet signal was present at pin 7 of the IC so I just soldered the out wire to the underside of the pin (spot the 1uf cap poking out of the right side of the board). No idea how it's working but remarkably it is. Although I do get some horrible clicking in certain settings. I tried upping the cap next to the LDR but no luck. In fact I took the cap out altogether at one point and there was no noticeable difference to when there was one in place. I might look to fix it in the future but I'm done with it for now. Can't wait to give it a run out! Hope you like it.

[Taylor]

Cool design, looks really nice!

[ListenLoudly]

Finished this a couple weeks ago, thanks to all the help on this forum! I used rotary switches for the multiplier and waveform, and allowed for an external tap tempo. I found the finishing (decal, clear coat, etc) to be the most difficult and time consuming part of the process. Hopefully I'll get better at that part  

https://www.dropbox.com/s/cyxnatfm80vb54a/2014-03-30%2018.42.57.jpg

https://www.dropbox.com/s/1salo0g5gm4rt2e/2014-03-30%2018.47.37.jpg

Had to use links; inserting a picture from my dropbox didn't seem to work...is there some trick to it?

[sdb guitars]

I've purchased three tap tempo tremolo board sets (not all at once) and I seem to be having the same problem with each of them so far - the LED flashes correctly and syncs with the tap tempo switch input correctly, but I'm not getting any audio through the board.  I've built two of the three boards now, and other than a couple of minor part substitutions, they are both exactly like the build document describes.  Here are the part substitutions I've made, as they are what I had on hand:

C1 and C2 (right off the crystal) - 33pf instead of 22pf - does not appear to be affecting the LFO, or at least not the blink rate of the LED, which is right in time with the tap tempo switch

C9 (parallel to R15) - 470pf instead of 330pf - this one is the only one in the audio path, right?

C14 (at voltage regulator) - 470nf instead of 330nf

I re-touched all of the solder joints, and verified that there are no solder bridges.

Here are voltages at the OP AMP

1) 3.60v       7.28v
2) 3.60v       7) 3.59v
3) 3.58v       6) 3.59v
4) 0.00v       5) 3.58v

Any help would be appreciated.  I'm ordering the correct capacitors from Tayda now, I'm just concerned because I've built two already, and had the exact same issue with both of them.

Thanks,

Shawn.