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Re: Transfer Console Monitor Controller

Posted: Mon Sep 12, 2022 11:08 am
by mediatechnology
Thanks Paul!
I'm looking forward to testing it.

On Sunday afternoon of the 4th we lost power for about 36 hours after a storm and I'm almost finished repairing damaged electronics.
We had hot lines drop onto CATV ground and things went down hill from there.
My bench work has involved changing a lot of MOVs.

Re: Transfer Console Monitor Controller

Posted: Mon Sep 12, 2022 12:40 pm
by Gold
That sounds bad. I hope you get everything sorted out soon. We are waiting to get electrical service in the mountains. The pole is in. We are waiting for the electrician to install the meter and the excavator to dig the trench. I hope we get a good ground rod. I'm leaving the electrician alaone because he seems like he knows what he's doing. He's retired from GE.

Re: Transfer Console Monitor Controller

Posted: Fri Sep 16, 2022 6:27 pm
by mediatechnology
"Monco" runs without any layout errors.

It's a really easy build: The hard part was getting everything around the house running after the storm.
Once I got to it the build and test went pretty fast.

KA-Electronics/Rockmore-Labs Monitor Controller

The power-on delay using the TL431 works rather well.
The +24V relay supply is galvanically-isolated from the +/-15V audio 0V.
A PS2501 optoisolator provides isolation between the 27.5V power OK voltage detector and relay control.

Re: Transfer Console Monitor Controller

Posted: Sat Sep 17, 2022 11:40 am
by mediatechnology
I tweaked the threshold voltage for the power OK detector by changing R41 to 11K and R42 to 121K.
After adding D11 to quicken turn-off the division ratio was changed by the addition of R42.
With the original values Vth was 28V and I thought that was cutting it a little close.
Raising R41 and then using R42 to hone in on 27V did the trick.

I need to touch up the soldering and de-flux the board before running final tests.
I did have a chance to listen though and I really like the feature that allows me to toggle between normal Stereo presentation and Difference.
There's so much that goes on in the Side channel its worth checking as often as Mono.

Looks like for now I'll have 1-2 boards available for anyone that needs one.

Re: Transfer Console Monitor Controller

Posted: Sun Sep 18, 2022 7:03 pm
by mediatechnology
I wanted to first check noise level of the Aux Output that can be used to drive an A/D.

Measured over a 20-20 kHz bandwidth at unity gain the noise is:
-98.5 dBu unweighted providing a DR of 125.5 dB
-100.5 dBu A-weighted for a DR of 127.5 dB

THD at 1 kHz 0 dBu output was 0.0006% which is near loop-back level of the test converter.
I'll fire up ULDO-Nacho with its -140 dBc THD and get a better read.

I also checked the Aux output to make sure that no clicks from monitor path switching was present.
It was dead silent.

Re: Transfer Console Monitor Controller

Posted: Mon Sep 19, 2022 1:56 pm
by mediatechnology
I used ULDO-Nacho to check the 1 kHz THD of "Monco" at +20 dBu input.

On the Aux output, at +20 dBu it measured just a tad over 0.0001%. (-120 dBc) (1246>5532>1646).

The Monitor output, with a slightly longer path and also at +20 dBu, measured 0.00012%. (1246>OPA2134 X2>1646).

The measurable harmonic was THD-3.