Building the tap tempo tremolo

EDLK · March 06, 2011, 09:55:11 PM

Thanks Taylor for the clarification on both these issues.

I am Italian, and love spaghetti, however not in my gear, my wiring is short and tight as possible. However, I do twist my pot wire and switch wires together to make them more manageable in the box. The led wires are not twisted, however all the other wires are, could this add to the ticking?

Taylor · March 06, 2011, 10:37:46 PM

Twisting by itself is no problem, but if you twist something carrying the LFO with something carrying an audio signal, you could have a problem. So if you twisted the LED wires with the in and out wires, for example, it could lead to ticking.

EDLK · March 06, 2011, 10:48:28 PM

Ok Thanks
I will keep the LED wires clear and short.
Are there any other leads coming off the board that should be run with out being twisted.

EDLK · March 07, 2011, 08:50:20 PM

I did the switching/LED mod and in doing so was able to shorten up my LED leads as well.
This cut down the ticking in the first 3 wave forms significantly. There is still a faint, but noticable tick. After the square wave it goes away 100%
I ordered up various size caps from 1u to 10u, I will try them out and let you know what value knocks out the tick.

Question on the Led brightness pot. It seams like increasing the led brightness reduces the level of the tick but all seems to "mud" up the signal.
What are the expected changes in the tone as the brightness pot is adjusted.
Is the other trim pot all gain/distortion adjustments. I am trying to understand the balance between the two trim pots and the over gain trim pot.

Thanks

Taylor · March 07, 2011, 09:04:27 PM

Hey Ed, I want to reiterate that you want to swap the 330p with something in the 1N to 10N, NOT 1u to 10u. 1u or higher will drastically alter the sound of the pedal, removing all but the lowest frequencies. Check out this link if you're not familiar with how these values relate to each other:

http://www.justradios.com/uFnFpF.html

Regarding the trims, there really should be no change in EQ. Basically, the trimpot right next to the PIC (the 14-pin chip) controls the optocoupler, lower this resistance to get a bigger difference between quiet and soft parts of the trem. The trimpot next to it just controls the brightness of the visible LED. It should not effect sound at all. Make sure not to put it all the way at the brightest setting. The trimpot above the TL072 controls the gain, and you should just set this AFTER trimming the one next to the PIC to give you equal volume in bypass and effect modes.

EDLK · March 08, 2011, 06:36:41 AM

yes, thank again for the clarification, it ordered the correct parts, just keep writing it wrong.
On the LED, it does seem to affect the sound of tick. When the led is brighter the tick is muffled sounding.
When it is lower it is a more defined tick sound. I assume one the cap is changed, this will not matter either?

thedrivel · March 08, 2011, 11:07:43 PM

Is this how you would wire an external gain?

Taylor · March 09, 2011, 12:14:22 AM

The points you've labeled 1 and 2 are connected inside the PCB, so you just need to use points 1 and 3. Looking at your pot from the front, wire them to the left most lug, and the center/wiper. It doesn't matter which goes to which.

EDLK · March 12, 2011, 02:12:33 PM

I pulled the 330p cap and inserted a couple of sockets, I then tried, 1n, 2.2n, 3.3n, 5n,6.8n, and 10n. None of which knocked out the ticking in the square wave from. In fact for the most part I could not notice any difference in the ticking sound or volume between any of the caps I tried. I did not pay much attention to the change in tone on the guitar signal as I would like to solve the ticking first and then see if I live with how it affects the tone of the signal.
Once I dial past the square wave from, the balance of the wave forms are clear with no tick.
Is there any thing else I can try. Would replacing the opto be worth a try. Is this a characteristic that has been reported before and solved by changing the opto.
I purchased my opto from small bear and most everyone who has reviewed there stock from small bear has had no issues.
Any additional ideas would be much appreciated.
Thanks

Taylor · March 12, 2011, 04:02:11 PM

Can you post a photo of your wiring?

EDLK · March 13, 2011, 03:18:47 PM

Here is the wiring, the cap in the 330p position is a 2.2 it was trying.

http://gallery.me.com/edlk#gallery

Taylor · March 13, 2011, 04:29:19 PM

Hmm. It would be better if that LED wires didn't run over the audio portion of the board (right side). I think at this point you'll need to try to adjust the trims differently unless you're willing to rebuild it using onboard pots. Try lowering the visible LED all the way, turn the gain to the middle, and adjust the trim next to the PIC until the ticking is tamed.

Are you using 22k trimpots and gain pot (would have to be 25k for the gain pot)?

EDLK · March 13, 2011, 05:17:00 PM

The trim pots are 22 K the gain pot is 25 K
I originally had the led wires around the board but shortened them as advised in earlier posts.
This was done simultaneously with the cap changes.
Is there any merit in re routing them around the board.

EDLK · March 13, 2011, 06:10:51 PM

I think I have every combination of trim pot and gain settings.
The one thing consistent is that the tick is does not change in sound or volume with any of the adjustments.
And as previously stated the cap value in the 330p location has not affect from 1n to 10n
If were any other form other than the square form, I would live with it, however this wave form is the one I use the most.
I'm game for any suggestions

Taylor · March 13, 2011, 06:18:12 PM

If the trimpots really have no effect on ticking, and a 10n cap doesn't, that's very weird. 10n should totally choke it at the expense of a lot of high end. I will try to ponder what could be happening in your build and get back later.

EDLK · March 13, 2011, 06:43:03 PM

let me clarify
The caps do not affect the tick in any noticeable way. the guitar signal tone was affected.
If I roll the led pot to full bright, the tick does "muffle" a bit, however the volume of the muffled tick is the same.

Ed

defaced · March 14, 2011, 08:54:21 AM

Found this in another thread, http://www.diystompboxes.com/smfforum/index.php?topic=90425.0. As Taylor has eluded to, your build technique may be what is causing the ticking. This person ended up needing to screen the PCB from the jacks to eliminate ticking. I'd be tempted to pull the circuit/pots/jacks from the box and start moving stuff around to see what, if anything, is coupling to cause the tick.

EDLK · March 14, 2011, 11:23:37 AM

THanks for lead,
My next move will be to pull everything out of the enclosure and see if screening parts from the board make any difference.

EDLK · March 15, 2011, 09:32:45 PM

Ok, here is what I have tried so far
I tried a different led, that made no difference
I pulled the led out of the holder and moved it around the enclosure and straight up in the air, that made no difference.
As suggested above, I pulled everything out of the enclosure and laid it on the bench, out of the enclosure I got the same tick in the on the same first three wave forms, strongest in the square form, and was a bit louder.
It did seam that touching the led wires affected the tick, making it louder?
I have a 2.2 cap in the 330p position.
Is this symptomatic of a bad opto?
Am I at the point where I need to rip all the pots off and install on board pots
Any other opinions or suggestions would be welcomed.
Thanks Ed

Taylor · March 15, 2011, 10:04:56 PM

Another opto might be a good thing to try. The pot wires don't make a huge difference really - they don't carry the LFO signal, so I don't think they would cause the really noticeable problem you're having. Sorry you're having so much trouble Ed! This hobby's supposed to be fun, not frustrating. $:-\$ Try a couple other optos and see how it goes. Allied electronics has them cheaper than anybody else.

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Building the tap tempo tremolo