Is There a Schematic Available for the CAPI VC528?
« on: October 10, 2020, 09:24:14 PM »
Hi All,

I recently posted a question about building a passive summing mixer:


I've been thinking about adding some type of subtle distortion to it, and was initially thinking of using something like a very gentle guitar overdrive (e.g. Mona Lisa, etc.).

I recently came across the CAPI VC528 and it's probably more like what I'm after. However, I'd prefer to build it into the summing mixer box and not have it as a separate 500-Series device (I don't have any 500-series stuff).

I realise that the CAPI VC528 is a commercial product but was wondering whether there is a schematic available for it anywhere? Failing that, is there any alternative to this device that does something similar?




Re: Is There a Schematic Available for the CAPI VC528?
« Reply #1 on: October 11, 2020, 07:15:09 AM »
I don't have a schematic, but I think the VP528 is very similar to the input channel of the old API desks, but without the mic input transformer and associated parts.
This scan of the 528 input module I uploaded to the Tech Docs section will be broadly similar.
(Scroll down...)


Re: Is There a Schematic Available for the CAPI VC528?
« Reply #2 on: October 11, 2020, 08:42:02 AM »


Re: Is There a Schematic Available for the CAPI VC528?
« Reply #3 on: October 11, 2020, 11:42:01 AM »
+1 what walrus said.   Api mic pres have a cleaner sound when used on their own.   An api console channel strip has a fader and a booster amp to drive all the bus, sub, aux,echo outputs.   You go through an extra amp and transformer out the channel and it creates a fatter sound but also tends to change clarity of the topend.   If I needed more clarity (Acoustic instruments)I would come out of the mic pre out.   But many times the kick and snare Bass, would sound better/thicker  coming out of channel fader out.   

The VP528 is a line level module and the real 528 channel strip would use the input 2520 as a combo mic pre or fixed line level active diff amp line input (tape in) When you use the vp528 module with another 500 series mic pre ,  there is an extra transformer in and transformer out as well as the Two 2520s.  Also in an actual api console,  there is a 550 or 560 eq module.   So when using the channel strip,  there is the mic transformer,  2520 amp,  to eq Prefade active unbalanced input 2520, to eq output 2520 to eq output  transformer, to channel fader to 2520 ch fader booster 2520 to ch output Transformer, to direct ch output.   So you have more stages than just the VP528.   Getting the filters are On VP528 are nice as well and more flexible than an original filter on an old api console.   

If I were to sell my console ,   I would order VP528s as well as Mic pres and some 550 eq’s to get the more classic sound of the console. As well as the active combining networks for mixing out of the box.


Re: Is There a Schematic Available for the CAPI VC528? New
« Reply #4 on: October 14, 2020, 01:26:36 PM »
+1 what Faze said.   ;D

Total aside:

Was experimenting with high-gain, attenuated output of a 312 style micpre placed at A1 of channel (528) or going straight to 2nd stage of 528 (A2), and some interesting shelving effects were had depending on insert point.

Edit: I'll have to make some audio clips of it down the road and share.
« Last Edit: October 15, 2020, 01:19:32 AM by boji »


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