Current Lover 2023 - another clock calibration question (no chirps)

[Mkstewartesq]

I have a calibration question around the Current Lover 2023; this is a build for a friend and I'm not that familiar with the underlying pedal or with flangers in general:

As background, I'm running this at 18 V using the 3007 chip.

For the clock trim pot, I took MadBean's suggestion in another thread and used a 20 K trim pot rather than a 10 K trim pot.  The instructions are to start with the pot set at 1/3 and adjust it to the point just before you hear any chirps at the peak of the flange sweep.

But as I go through the sweep, I'm not hearing anything that I would characterize as a "chirp" – the tonality definitely changes and the tone gets more metallic and pitch shifted as I go through the sweep - and there's even bit of an ascending and descending nasally whine at points – but not anything I would characterize as a chirp even when I take the trimpot to 100%. Does anyone have a sound sample or reference for the "chirp" that I should be listening for so I can set the trim pot to just before that chirp kicks in? Or any other guidance to get this pot dialed in correctly?

Alternatively, other guidance for properly setting the clock? I did see the instructions in the other thread about setting the clock speed frequency to where it should be - but I don't have an oscilloscope. I do have a DMM that measures frequency but I'm not sure how in this particular circuit to make that work to get the reading (i.e., where to place the DMM leads, etc.)

Thanks,

Mike

[skeeter]

should sound like trp trp trp ,I use a tech21 9v that stops the chirping , with my digitech 9v the chirping starts again this pedal can be difficult to bias more so than the mxr ,why 18v

[Bio77]

You can measure the frequency of pin 2 and 6 of the 3007 in matrix mode adjusting the range knob. The frequency range for a vintage EM is ~35-680kHz.  Since this one has 1024 stages instead of 512 you are looking for 70-1.2MHz.  You should check out the frequency capabilities of your DMM first, some can't measure very fast rates.

When I set these up, I use the low end (70kHz) as a starting value.  After you set this, if there are no weird sounds at the extremes of the sweep, you can leave it.  Occasionally there are weird sounds (chirps); you will definitely recognize these if they are there.  In this case you need to dial the clock trim until they are gone.

[tron]

Just finished building mine (2023ver) with mn3007 and 18V, and it sounds nice. With a 10k clock trimmer (fully CW) I get a max delay of ~8ms. I thought about changing the C21 cap from 22pF to 47pF. Holding another 22pF in parallel with the one on the board gets me 13.5 ms max delay. Now I am seeing here (and on the schematic) that I could use a 20k clock trimmer. My question is what is the delay time of vintage units? Was it close to the 8 ms I already have, or more like 15 ms?

EDIT: nevermind. I think it's fine as is. I wasn't getting where the factor of 2 in the equation delay = 1024 / (2*clockfreq) comes from, but I understand it now. So if the original had 512 stages with 35kHz clock, then it would match the 1024 68 kHz clock I have here. Sweet. This is a nice low noise chorus/flange effect, with fairly high (~2Vpp) headroom.