Mix Bus Compressor from scratch

[DaveP]

These are all very good ideas and I'll try them and report back to the forum.
best
DaveP

 

[Johnny1234]

Thanks Dave, you are the man.

 

[DaveP]

I have taken Jacob's advice and it now looks like this:-



I was never happy putting a noisy resistor on the input so this is a much better arrangement.

I have not yet had the time to fully test it yet, but the negative voltage level is identical to the former circuit, so that looks promising!

Thank you Jacob
best
DaveP

 

[Johnny1234]

quick question. Will the dc control voltage not saturate the core of the input transformer.

 

[gyraf]

There is no current flowing, impedance at grid is near-infinite

 

[Johnny1234]

Ah no current, just potential change.

 

[evil grill]

I am trying to match the "Ohmite" dials of the input and threshold controls, for the attack and Release switches.





I have produced the dials in MS Paint and will use some cellophane circles to give a durable finish.



best
DaveP

Not wanting to hijack this interesting thread, but what is the process for marking the front panel? I have a compressor that will need text and symbols.

 

[MidnightArrakis]

what is the process for marking the front panel? I have a compressor that will need text and symbols.

[what is the process for marking the front panel?] -- Depends upon -- how/what -- it is that you want to have this done and/or you would like for it to look. Putting text and symbols onto a front-panel can be accomplish by:

1) Magic-Marker
2) Dymo-Label
3) Silkscreen
4) Engrave (mechanically or by laser) & White-Fill/Black-fill (my preference)
5) Crayon
6) Lipstick
7) Hammer and chisel & white-fill/black-fill

I had designed this rack-panel for its graphics and text to be "engraved & white-filled":



/

 

[DaveP]

what is the process for marking the front panel?

I worked out the angles for the switch positions and drew it on MS paint. I printed off copies and enlarged them until I got the size right.

When it was finished, I drew a box around each one and coloured the text red. I was then able to paint the white parts black without losing the text.
Finally, I painted the red text white and printed it off. I carefully cut circles from some thick cellophane, like that you get from a new shirt box.
best
DaveP

 

[ruffrecords]

I worked out the angles for the switch positions and drew it on MS paint. I printed off copies and enlarged them until I got the size right.

When it was finished, I drew a box around each one and coloured the text red. I was then able to paint the white parts black without losing the text.
Finally, I painted the red text white and printed it off. I carefully cut circles from some thick cellophane, like that you get from a new shirt box.
best
DaveP

Now THAT is real DIY.

Cheers

Ian

 

[DaveP]

I decided to revert back to the original threshold configuration, but with one addition. I made the original change because I couldn't get any positive pulses from the diode arrangement I had. Then I discovered that you either need a second diode or a resistor, to earth the negative pulses. When I added the resistor the negative supply worked normally. I also changed the signal diode to a rectifier diode because it is possible to exceed the voltage of the original 1N4048 with this circuit. This is the revised circuit.

The Grundig tape recorder schematic I copied, only had a fixed attack and release timing and the threshold control was factory preset. My version with variable timings starts to oscillate with very fast timings so I will have to modify them. Any timing ideas from other users of mix bus compressors will be appreciated.
best
DaveP