Dolby CAT22 mod - the extras

[tata]

hello gents,

could you please help me modding the CAT22 further than the lift (R109, R209..) and jump (R109 lifted and wired to R186, etc) mods ?

i did these, did the switch mod too (lift+jump in one), and i also added some potentiometers. 50k pots seem to have a nice effect in series with these resistors.

this is my demo of a lift mod (only) + some more fun

manual says: "The overall signal gain of the compressor is precisely set during the manufacture by selecting R117."  and R217, R317, R417 - as the compressors are identical, afaik.

does this mean we can change the gain by changing those resistors? iirc R317 is 10.7k in my "adventure CAT22" module. i added a 10k pot in series to it - so far i hear no difference in sound. should i remove the R317 and leave just the pot?

can we change crossover freqs 'easily' ? band2 may be trickier than the others (?)


thank you for all your help

 

[tata]

here is what i have now : (i have the in/out potentiometers wired in since this photo)

its _awesome_, and it could be more awesome.. if anyone is intrested in modding this further.
im too noob to do all the mods id like to see/hear.

here is a fairly good quality scan of the CAT22 NRM, i hope it helps:
http://beatbybit.com/gears/Dolby/Dolby_CAT22.zip

for eg. id like to know if its possible to tune the lowpass filter w/ a potentiometer somehow?

thank you

 

[synthiaks]

This is really interesting me , What exactly does this mod do? (Bypassing the Noisereduction circuit?) Just from a quick glance at the Schematic the points J, M ,F ,S could be wired as separate inputs for the compressor stages. Or i guess you could choose to wire them before the Filter Circuit. I would LOVE it if someone could roughly explain how the Comp stage is working.

 

[synthiaks]

So after some staring on the schematic i think it might be possible to mod the CAT 22 into a CAT34.  You would then have sliders for the gain/Reduction on each FQ Band for example. I have a 34 at work so im going to open the Remote up to see whats inside sometime next week.

I still havent figured the comp part. Is it a differential FET amp where the 2 factory Resistors are? It could be the threshold? the 3rd resistor the makeup gain. But this is wild guessing.

 

[synthiaks]

so, i opened half the 43 up, that i have at work.  It is a lot more going on in there than i thought... Sadly the fader unit had a screw that vas F-ed so i couldn't get it open without a drill, and i didn't want to go there, so what kind of circuit they have in there will remain unanswered :-(