signalflow
Well-known member
Ok, so. After the mix amp & the VCA compressor circuit. It feeds the master fader then into a balancing circuit?
-casey
-casey
Mini SSL? Schematic included...
- Thread starter jwhmca
- Start date
Help Support GroupDIY Audio Forum:
helterbelter
Well-known member
Ehhhh, am I missing something ? the summing amp IS a mix amp. You'll want to swap these.signalflow said:
signalflow
Well-known member
jwhmca said:
Irony at it's greatest ;D
helterbelter said:
Ok so a mix amp is a summing amp. But I'm confused at what I need to swap.
-Casey
thefastvinny
Well-known member
The Master Fader is the VCA of the Mix Amps. QB Mix amps are VCA's. Not much going on after the Master Fader other than just distribution... What was the original question?
tinwhiskers
New member
FAO, @jwhmca : I hope you don't mind my asking, did you ever finish this project? I'm looking to do the very same thing, but it's a step-up from my previous projects, so I'm looking for any info/guidance I can find.
I've asked on @helterbelter 's 552 thread too. There, they convert their mix amp cards to a quad comp using the s/c from the Gyraf PCB. With that in mind, I was wondering if one could work back from the Gyraf PCB to make a set of mix amps...
I note the DBX202X VCAs I see in the G-series service manual are absent from your schematic. In @helterbelter 's post here, they mention 2x2 2152 VCAs w/ fader controlling level. I'm wondering where the VCAs fit into the eqn (partly as I have the opportunity to pick up some 202Xs).
At present, I'm trying to simplify the circuits I see for a DIYable set of G-series mix amps, and am understanding more the more I read and sit with the schematics, but it's still out of my reach as yet what with the quad comp, etc., being enmeshed with the mix amps.
I'm also wondering how the actual channel summing connections look as hitherto I've only had experience with simple passive summing arrays. Reading the Forsselltech doc on active/passive summing, it looks as though the main difference here is more in the connection of the amplification stage rather than the resistor network.
I'm a new member so cannot message directly, but if anyone has any pointers—at all—on how the G series sums then amplifies the mix, I'd be v grateful to hear from you.
Cheers!
P.S. I should also mention my motivation here is curiosity and personal use only; I'm struggling as it stands, and have no designs on making this a commercial endeavour!
Michael Tibes
Well-known member
The SSL mix bus is basic active summing, SSL enhanced the noise performance of the mix amp with the added low noise transistor circuit. The vcas are not involved in the summing, they are there as master fader and bus compressor.
The summing amp and the vcas are located on the same physical card / schematic, but the functions are independent from each other.
The diy bus compressor designs don’t include the summing amps.
I don’t think that there’s any stardust in the SSL mix amp, a 5534 based active summing circuit should get you there for a few channels. The low noise aspect of the SSL circuit will get more relevant with higher channel counts.
Hope this helps,
Michael
The summing amp and the vcas are located on the same physical card / schematic, but the functions are independent from each other.
The diy bus compressor designs don’t include the summing amps.
I don’t think that there’s any stardust in the SSL mix amp, a 5534 based active summing circuit should get you there for a few channels. The low noise aspect of the SSL circuit will get more relevant with higher channel counts.
Hope this helps,
Michael
