Transformerless Feedforward Vari-Mu

[Heikki]

Those 2.5 - 6 -1.2s might be dual time constants like release time position 5 & 6 in Fairchild 660 viewtopic.php?p=37#p37

[Script]

That makes sense.

[Script]

The Recom R12-150B is mighty in price. Is there a cheaper alternative you can recommend?

Or a power toroidal backwards also could work, no?

[Heikki]

There are no cheaper alternatives for Recom R12-150B as far as I know. Since the whole thing is powered by 15V DC wall wart you can't use a transformer. You could use a linear power supply and a custom power transformer but it might not be cheaper.

[Script]

What meter is good on this? 200mA? 1mA?

[Heikki]

200 uA meter should be used. LED D7 is also gain reduction indicator. If I were to build another one I would just wire LED D7 to front panel and leave out the meter.

[Script]

I like that idea. Did something like that on analag's DAOC with LED in antiparallel to optocell . But ended up also adding meter slowed down with a cap to show an approximation of average.

[Script]

What is diode D1 on the dcdc board? Same as D9 on main board (170V/5W)? Or just a 400x?

And on the layout picture, D9 is not installed. Not really needed there?

[Script]

Can't find the AM6T-1215D anywhere. Is there an alternative?

I can get hold of a 1218D by same maker, but gives only 166mA and would need to be pulled down to +/-15V. Is that still enough for hooking up two boards for stereo? If not, I might have to think of something entirely different.

Got it.
DCWN06A-15 by Mean Well should work. Same as in VariMu (v1) compressor.

[Script]

Resistors in the sidechain better be 1/2 watt or is 1/4 watt ok?