20 February 2014

Tube compressor with 6AL5 sidechain and remote-cutoff pentode.

Started a discussion at GroupDIY and DIYAudio. Saw a circuit fragment in an ARRL handbook from 1961. While I am not a designer at all, (and still find it a difficult mental exercise to calc a plate curve...) this looked intriguing.The circuit fragment uses a 6AL5 in the side chain. The circuit calls for a pentode input stage and uses the suppressor grid on the pentode; I've seen other circuits that do this with 6BA6, and decided to give it a swag.

updated  26 Feb 21:00 HST

The orig schematic is here:


A lot of problems are identified with this draft, and there is another one being drawn. The output is missing a coupling capacitor in this drawing, the side chain is directly from the ARRL handbook, except the fixed resistors in the off the sidechain transformer replaced with pots. The values are just guestimates. The other values are also just taken from the RCA handbook, without doing any calculations, so basically place holders. There have been numerous criticisms, which I will summarize later. The two threads are here: GroupDIY 6BA6 thread & DIYAudio=6BA6 compressor thread

Here is another draft. Still not sure about any of this, but it is a learning platform.


EDIT: the bad first draft keeps popping up on google, and it's no good, so i moved it away hoping it will disappear.

Got some more feedback from DIYaudio and a few new tube suggestions. Looking for some more criticism. Also, maybe use the side chain with a 6ES8 triode? One of hte mods suggested for the PRR Varimu. Also, drawn poorly here, but why not just strap the screen to plate?

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