DIY Stompboxes => Digital & DSP => Topic started by: funkgang49 on October 18, 2016, 06:16:58 PM

Title: Adding Tap Tempo to Delay
Post by: funkgang49 on October 18, 2016, 06:16:58 PM
I built a Multiplex Jr. Delay from Josh over at 1776 Effects and I am trying to add Tap Tempo using the Taptation chipset & microcontroller from the Tonegod on the TapTempo Board from Barry at GuitarPCB (see build docs)
Multiplex Jr.:
file:///C:/Users/funkman49/Documents/Footpedals/Effects%20Layouts%20Schems/Current%20TJ%20pedal%20schems/Delay%20&%20Reverb%20Effects/Stutter-Step%20Schems/Multiplex-Jr-BOM.pdf (http://file:///C:/Users/funkman49/Documents/Footpedals/Effects%20Layouts%20Schems/Current%20TJ%20pedal%20schems/Delay%20&%20Reverb%20Effects/Stutter-Step%20Schems/Multiplex-Jr-BOM.pdf)

TapTempo v2:
file:///C:/Users/funkman49/Documents/Footpedals/Effects%20Layouts%20Schems/Current%20TJ%20pedal%20schems/Delay%20&%20Reverb%20Effects/Stutter-Step%20Schems/TapTempo_v2_Build_Doc.pdf (http://file:///C:/Users/funkman49/Documents/Footpedals/Effects%20Layouts%20Schems/Current%20TJ%20pedal%20schems/Delay%20&%20Reverb%20Effects/Stutter-Step%20Schems/TapTempo_v2_Build_Doc.pdf)

After verifying that the Multiplex Jr. circuit is working properly and measuring proper voltage on the Tap Tempo board as well as functioning Tempo Scale LED, working momentary footswitch, double time switch, and tempo scale switch. I proceeded to connect the Multiplex Jr. to theTap Tempo board.

All Tap Tempo functions are working properly, however I cannot get the Delay to respond correctly or sound like a delay.

I tapped into the MP Jr. at pad 3 for the Time pot and connected the other end of that wire to the PT6 pad of the Tap Tempo board as is suggested in build docs for the GuitarPCB D'Lay.

With the 2.7K R25 resistor in place I get no delay effect except for some mild & occasional popping sounds. Changing R25 to 2.2, 2, 1.8, 1K (this value is used on the D'Lay board), as well as inserting a jumper I go from louder popping to increasingly weird blips, bleeps, and bloops.


I am not using the Modulation from the TapTempo v2. I prefer the sound of the Macron optocoupler and the ability to use the Depth control for the Modulation which is supplied on the Multiplex Jr. board so I have omitted R4 & Q2 on the Tap Tempo board. There is no connection from the pin 6 of the Tapflo chipset to pin 7 of the digital potentiometer.

See gutshot:

Could my tap-in point on the Multiplex Jr. be the problem?
and/or could my use of the modulation on the Multiplex and not the modulation circuit on the TapTempo board also be a contributing factor?

Any insight or advice would be greatly appreciated!
Title: Re: Adding Tap Tempo to Delay
Post by: slacker on October 19, 2016, 01:26:46 PM
If you aren't using the taptation's modulation then pin 7 of the digipot need to be connected to ground, I'm guessing you haven't done this. I haven't seen the layout but you can probably do this by jumpering the outside two pads of where Q2 is supposed to go. Also you said "tapped in to pad 3" of the delay time pot, which is the right place according to the schematic but you need to remove the delay time pot not just add the connection for the taptation, in your photo it looks like the pot is still connected. The pot on the taptation replaces the existing delay time pot.
Bear in mind that the Multplex's modulation will probably mess with the accuracy of the tap tempo, it might work fine with modulation off but with it on it won't be accurate.
Title: Re: Adding Tap Tempo to Delay
Post by: funkgang49 on October 22, 2016, 03:53:30 PM
Slacker - you nailed it!
I jumpered the outside pads of Q2 together and with a slight adjustment to the value of the MP Jr. R25 resistor and a tweak of the output of the modulation the Delay and tap tempo work beautifully together.
There is a slight inaccuracy of the tap tempo time when the Modulation depth is all the way up but not anything significant - I can definitely live with it.
Thanks so much for your help!
Title: Re: Adding Tap Tempo to Delay
Post by: Boba7 on December 06, 2016, 10:41:32 PM
Hi funkgang49, would you mind doing a short video showing how (in)accurate the tap tempo is with the modulation engaged? That's be very helpful for me! I'm planning on building a Madbean Dirtbaby with tap tempo... Maybe... :)
Title: Re: Adding Tap Tempo to Delay
Post by: Boba7 on January 09, 2017, 05:28:20 PM
Hey funkgang49, any chance of seeing a short video of the tap tempo with modulation from the Multiplex? Pleeeeaaase? :)