Just had a email with Tat - any plans to incorperate super sidechain into design - this could then be included in tats new case.
Regarding mains transformer - it may be worth the forum coming up with a "universal" transormer for valve projects eg 0-7 0-7 at x current for heaters and y volts at y current for HT. May be worth considering winding for 48V also. Extra windings for solid state sidechains etc would be nice but i think it gets "too" custom. If enough people are intersted, we could start getting some bulk pricing to drive cost down.
Any thoughts :?:
Just had a email with Tat - any plans to incorperate super sidechain into design - this could then be included in tats new case.[/quote]
no plans to change the PCB in any way :grin:
if you want options you can mount a switch for different slopes
well, here are a few sound samples of a vocal ad lib recording, 1st one is as recorded, 2nd one compressed with the D-AOC. Furthermore the resulting waveforms can be seen here. The 16 year old female singer is one of my pupils, recorded at school with AT4033 Mic and Yamaha 01V96 Mixer. No further treatment. Happy listening.
after building the first prototype I had a one (self made) problem:
I thought it doesn't compress. passed audio and measured well, but it just didn't want to compress. mhm.
I put in a (red) LED, paralleled to the Vactrol LED (to watch if it will light - since I was able to measure Audio at that point). There was no light, but - compression.
I emailed analag, kubi and viitalahde (since Jakkoo has a running build), and did some experiments while waiting for answers.
today I did some more measuring for this post:
Input 100%, Threshold 100%, Output adjusted for 0 dB Gain without compression.
(= this is although the minimum threshold before compression)
again, sockets were used paralleled to the Vactrol LED:
(blue LED antiparallel in this test)
analags circuit is working as is. my self made problem was the input level.
I tested with my nominal level of +6 dBu, and with the Input and Threshold full open: no compression. (rowan and jakkoo seams to like / have HIGH levels).
with LEDs or Resistors paralleled to the Vactrol LED, you can mod the D-AOC for different slopes, and lower Threshold. use sockets to test what you like best, or if you want to be crazy: use a switch.
[quote author="TomWaterman"]Why was it not compressing much with the input gain at max...there is a lot of range on the threshold control no? Why not just drop it? Was that a +6dBu input signal?[/quote]
would be better to label it "compression" instead of "threshold".
with the compression potentiometer at 100% you have the lowest threshold, there is no compression at 0%.
Input Level at 100% and "compression" at 100% is the lowest threshold, without any mods compression will slowly start at an input level of +12.5 dBu.
[quote author="TomWaterman"]Input level is purely an attenuator at the input of the first tube grid.
But either I'm going mad or it is AFTER the gain reduction vactrol potential divider...hmm[/quote]
you are not going mad, you are right. and the "compression" control is after the Input level control :green: