NEW PRODUCT: Taptation Tap Tempo controller

[HellenButterlips]

I finally completed building the DIY Stompboxes D'lay with Tap Tempo (Taptation) this evening.  Everything seems to work as expected, with a few odd issues.
1) All functions of the tap tempo mod work as described - including the "Double Time" switch and the On-Off-On selecting of beat-subdivisions, however when I actually tap the DPDT, it's being read as half notes - everything is translated twice as fast. For example, tapping at a rate of 40 BPM comes out as 80 BPM.  The LED's accurately reflect the beat post-translation, but I don't see how the taps could possibly be read as double the speed.  Is this the way the mod is supposed to work, or should I be able to tap in the quarter note subdivisions?
2) After tapping, there is a full measure (4 beats) of greatly increased delay speed before it settles down to the 'cut time' described in bullet 1.  This doesn't happen when I adjust the delay using the "Time" pot, only when tapping in the tempo using the DPDT switch.
This all leads me to believe that I possible have a faulty Taptation IC.  The digital POT seems to be functioning appropriately.  Any ideas?

[HellenButterlips]

I finally completed building the DIY Stompboxes D'lay with Tap Tempo (Taptation) this evening.  Everything seems to work as expected, with a few odd issues.
1) All functions of the tap tempo mod work as described - including the "Double Time" switch and the On-Off-On selecting of beat-subdivisions, however when I actually tap the DPDT, it's being read as half notes - everything is translated twice as fast. For example, tapping at a rate of 40 BPM comes out as 80 BPM.  The LED's accurately reflect the beat post-translation, but I don't see how the taps could possibly be read as double the speed.  Is this the way the mod is supposed to work, or should I be able to tap in the quarter note subdivisions?
2) After tapping, there is a full measure (4 beats) of greatly increased delay speed before it settles down to the 'cut time' described in bullet 1.  This doesn't happen when I adjust the delay using the "Time" pot, only when tapping in the tempo using the DPDT switch.
This all leads me to believe that I possible have a faulty Taptation IC.  The digital POT seems to be functioning appropriately.  Any ideas?

Update:  After some debugging, and touching up a few of the solder joints, I was able to resolve issue #2 (the odd quick beats when setting the tempo).  I'm still having issue number one, and I've noticed it's a bit quicker than double-time.  It's definitely mis-reading the taps, and I have the same issue when simply grounding the input pin on the chip, so it's not a problem with the DPDT switch or anything in its path.  I definitely suspect a faulty chip (which will be a pain because I soldered it directly to the board), but I'm hoping some of you SME's can provide some alternative debug routes.

[The Tone God]

Update:  After some debugging, and touching up a few of the solder joints, I was able to resolve issue #2 (the odd quick beats when setting the tempo).  I'm still having issue number one, and I've noticed it's a bit quicker than double-time.  It's definitely mis-reading the taps, and I have the same issue when simply grounding the input pin on the chip, so it's not a problem with the DPDT switch or anything in its path.  I definitely suspect a faulty chip (which will be a pain because I soldered it directly to the board), but I'm hoping some of you SME's can provide some alternative debug routes.

Sorry for the slow reply.

What type of switch are you using ? Is this a toggle or momentary switch ? If you are using a toggle switch you need to set the Tempo Clock Pulse Mode Input to low / ground.

Andrew

[JoeEsh]

Is this possible? Connecting 2 delay units to one Taptation unit giving 2 different taps - like quarter and dotted eighth?

[acehobojoe]

Joe, I would think you can just try to run the clock out from one to the clock in on another and it would work, but with just one I'm not sure! I'm definitely no expert.

I was actually posting to show my schematic for the taptation so far. I was wondering if some of you could look it over. The only thing I need to change is to make a rotary for the time pot.
http://i.imgur.com/d22Mpu2.png

[Njkke]

Hi! In my build there's this problem: the led blinks right but the repeats are out of synch.
The wire between tap and pin 6 is 1cm long, it's not a ground problem, I think.
 I've tried 2 different taptation kits, 2 different delay boards and 2 different pt2399 chips: delay totally out of synch, something like 20bpm faster (or useless tap tempo, if you wish).

[mrsuspend]

I have exactly the same problem as the previous poster: The LED shows the correct tempo but the delays are audibly too fast, definitely out of usable range tap wise.
This is a build with PCBs from Musicpcb and JMK. Surely this can't be a digipot issue if the LED shows the correct time..?


/Magnus

[lars-musik]

I have to chime in here: I made the same out-of-sync-experience with the tap tempo chip available in Germany from uk-electronic. Tried it with a DBD and a Rebote 2.5 (also tried several pt-2399, but I admit all from a chinese ebay source).

I thought maybe the pin 6 resistor for the VCO might be the culprit and tried to adjust it (tapped to a metronome then measured the resulting tempo at various tempi) but the discrepancy turned out to be non-linear. I just ordered a taptation chip to see if it is the AVR but now I read you have the same trouble with the taptation I am afraid the pt2399 might not be consistent enough. I just wonder why so many tap delays seem to work?

[mrsuspend]

I have to chime in here: I made the same out-of-sync-experience with the tap tempo chip available in Germany from uk-electronic.

Hi Lars,
Did you use a pcb and if so, which layout?

/Magnus

[lars-musik]

Hi Lars,
Did you use a pcb and if so, which layout?

/Magnus

This kit:
http://www.uk-electronic.de/Download/Beschreibung%20Tap%20Tempo%20mit%20TA.pdf

Plus these etched layouts:
DBD:
http://revolutiondeux.blogspot.de/2012/01/mad-professor-deep-blue-delay.html
Rebote 2.5:
http://www.tonepad.com/project.asp?id=51

Any ideas?

[mrsuspend]

Any ideas?

Not really except that the problem is more likely to be with the PT2399 as the tap kits are completely different.
I bought mine from Musikding but people have pointed out that even good batches vary quite a bit.

/M
 

[mrsuspend]

After wading through the entire thread it seems there may be a few reasons for the tap tempo problem:

• The Echo Base modulation may interfere with the tap even when turned off and may have to be disabled
• Someone suggested inserting a 1k resistor between pin 6 and the taptation
• (Most probable cause) The PT2399s are notoriously dodgy and you'll just have to buy a bunch and experiment.

I haven't tried any of these yet myself.

Edit: I am a bit suspicious still about the MCP41100 because of its 30% tolerance. I'll probably buy one or two more to test.

/Magnus

[mrsuspend]

Well, I measured my MCP41100 and it's only 80K so there it is...
I'll try to get a better value digipot somehow, maybe someone on the forum could part with one? I'll gladly pay a premium for a good one!   

/Magnus

[blearyeyes]

Just finished a GuitarPCB Delay and Taptation daughter board. At this point things are pretty hit and miss. The guys a GuitarPCB measured a 20% tolerance for the PT chip speed and 10% for the Pot chip resistance.

Is it possible to get this to work properly with these kinds of tolerances and if so How?

Is it just hit and miss and buy a ton of chips? 

Dan S.

[mrsuspend]

Well, the PT2399s at least are very cheap- around £3 for 10.
The digipots are another matter at £2.50 each.
Yes, I'd say it's pretty hit or miss. 

/Magnus

[blearyeyes]

Well it looks like the last fellow at GuitarPCB had a bad TT chip.
Replacing it fixed the issue he had. 

[blearyeyes]

Tried two TT chips, several pot chips and 5-6 PT chips and every time the the repeats are faster than the LED wether tapped or set by the speed control. It seems to be very consistently faster and seems to be by the same amount. I tried a trimmer and you can calibrate it at one speed like slow, then it will be out at another like fast. Always faster without the trimmer..

Any help would,be appreciated

[acehobojoe]

I hope someone has a solution too!

[mrsuspend]

Have you measured the Digipots?

/Magnus

Tried two TT chips, several pot chips and 5-6 PT chips and every time the the repeats are faster than the LED wether tapped or set by the speed control. It seems to be very consistently faster and seems to be by the same amount. I tried a trimmer and you can calibrate it at one speed like slow, then it will be out at another like fast. Always faster without the trimmer..

Any help would,be appreciated

[blearyeyes]

Not yet because I bought two digipots with the two TT chips and one from mouser and they all behave the same. Also the PT chips I have are from three different vendors and so far all behave the same.. I'll check the digi pots tonight if I get a chance. I guess I figured that since they came with the taptation chips as a set they would be tested if for no other reason than to save on these kind of support issues. I'll post my findings.

Thanks for the reply.