skal1

pico se ll calibration procedure
« on: August 06, 2019, 04:03:35 PM »
Hi  lads/gals,

Do anyone of you, know how  the calibration procedure ,for the pico is done correctly .

pico se ll  auto/peak/rms mode plus A/R board, any help would be appreciated


Cheers

skal


Script

Re: pico se ll calibration procedure
« Reply #1 on: August 06, 2019, 05:15:54 PM »
It's been a while for me, but you have the original SE Ii boards plus AR board?

If so, stuff them correctly and there's not much calibration needed.

Only AGC distortion for as low as possible (use 1k frequency and adjust 2nd/3rd harmonics looking at scope). 

And, IIRC, overall gain of the AGC when not compressing. That's it.

When using  Roger's original AR board, I think it simply replaced one resistor (or a jumper, can't remember) on the main board.

skal1

Re: pico se ll calibration procedure
« Reply #2 on: August 06, 2019, 05:27:30 PM »
Hi  Script,

so whats the detection pot for

skal

Script

Re: pico se ll calibration procedure
« Reply #3 on: August 06, 2019, 07:07:39 PM »
Am not at home right now and might be confounding with number of trimmers in different comp.

How many trimmers are on the board?

If its only one trimmer per channel, then those are for optimizing the harmonic distortion of the gain cells. Set for lowest distortion. Although some might deliberately set for higher harmonics. Same left and right.

If it's two trimmers per channel, the second one is for adjusting the volume fed into the gain cell, placed before THAT AGC chip input pin.

skal1

Re: pico se ll calibration procedure
« Reply #4 on: August 07, 2019, 03:16:30 AM »

If it's two trimmers per channel, the second one is for adjusting the volume fed into the gain cell, placed before THAT AGC chip input pin.

yeah thats the one , so whats the procedure for setting that trimmer then.

cheers
skal

abbey road d enfer

Re: pico se ll calibration procedure
« Reply #5 on: August 07, 2019, 03:52:32 AM »
If it's two trimmers per channel, the second one is for adjusting the volume fed into the gain cell, placed before THAT AGC chip input pin.
According to R. Foote's original schemo, it is in the RMS detector input, so it would change/adjust the threshold setting.

yeah thats the one , so whats the procedure for setting that trimmer then.
It's left to your appreciation and somewhat depends on the nominal level and your comfort zone.
« Last Edit: August 07, 2019, 05:19:31 AM by abbey road d enfer »
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Script

Re: pico se ll calibration procedure
« Reply #6 on: August 08, 2019, 05:54:43 AM »
Calibration best done in RMS mode.

Set RMS In trimmer for equal threshold levels left and right.

Adjust 2nd order harmonics to the same level but not lower than your soundcard, for example, when using software signal generator -- for lowest distortion. Use 1k frequency,  or 100k or both. Then set for lowest 2k /200k.


 

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