Keeley - Bassist Compressor

[x-tn]

https://robertkeeley.com/product/bassist-compressor/

The Keeley Bassist Compressor provides true high-fidelity compression and limiting.
...
is built around the exotic and extremely high fidelity THAT Corp. 4320.
...
It uses high performance Voltage Controlled Amplifiers, on board true-RMS detector, and ultra high performance op-amps
...
Where our older compressors were based on the CA3080 or the LM13700 and are perfect for single coil guitars,
the new Keeley Bassist Compressor has no problems with active pre-amps and line level input signals
...
you now have rack-mount quality at your feet.
...
The timing capacitor gives you attack and release times that are adaptive to your playing level or the signal input to the compressor.

http://www.bassplayer.com/effects/1167/ ... edal/49148

[lohstah]

similar to the carl martin comp probably, using the 4320 instead of the 4301, so they don´t have to deal with the dual supply voltages.
otherwise, those two chips should be pretty identical. slightly better THD in the 4301 model.

very curious to see the insides.

btw, built a carl martin comp clone and it sounds awesome.

[lohstah]

btw 4320 seems only to exist as surface mount versions, QSOP and QFN.

[RobertKeeley]

similar to the carl martin comp probably, using the 4320 instead of the 4301, so they don´t have to deal with the dual supply voltages.
otherwise, those two chips should be pretty identical. slightly better THD in the 4301 model.

very curious to see the insides.

btw, built a carl martin comp clone and it sounds awesome.

Howdy Builders!

The 4320 requires a substantial amount LESS V/R...CURRENT.
We added a nifty Threshold indicator that far exceeds the performance and noise of a comparator circuit. I've almost decided to never use a comparator in an effect pedal.

According to THAT Corp chief engineer we were the first to design a stomp box with the 4320. He was very glad we broke that market. Another engineer enjoyed using it with his bass and said it had a very organic tone, nice compressor. Pretty darn cool for a guy that has spent his life listening to compressors.

Robert Keeley Electronics

[lietuvis]

Hello, found on web compressor bare pcb posted possibly by Sir Robert Keeley himself. That picture helped me to almost trace schematic but without values. As I understand input is done by inverting amp with high impedance input topology something like mutron 3, compressor very likely is done close to that4320 demo board and threshold indicator is from that corp design note 123 http://www.thatcorp.com/datashts/dn132.pdf as in figure3. All very clever and neat.
However I took a brave step to try design that4320 compressor into 1590A enclosure. My setup is slightly different to Roberts design, input is set as voltage follower with gain of 1, compressor as demo board and threshold indicator I took from Carl Martin that4301schematic, so not much of my own design apart PCB. I have to say it works ok but I have some issue. When Ratio is set to 1:1 (no compression) and if I set Gain to max I get distortion at the output. So I'm interested in some of Roberts compressor resistor values marked as R27,R8,R13 on that pcb.
For now adding some pictures and later on will post schematic and PCB files as all work is still going on.

[vadgrek]

For now adding some pictures and later on will post schematic and PCB files as all work is still going on.

Hi! Now, what about schematic and PCB files

[lietuvis]

For now adding some pictures and later on will post schematic and PCB files as all work is still going on.

Hi! Now, what about schematic and PCB files

Hi, here is the pcb file for sprint layout, haven't really draw a schematic for it but used stock demo as base, input buffer as unity gain, nonlinear capacitor is from one knob squeezer and indicator is from carl martin that4301 compressor.
That corp now have pedal page on their website so as for complete schematics you can look there http://www.thatcorp.com/pedals/index.html