OK, I know this topic has been done several times over the years, but the last I found was from 2012 and some of the info is now outdated. Was hoping to get a few quick pointers on the current state of things, maybe something I missed in my search.
Finally getting house plans together (after a decade of medical school etc) and am just gathering thoughts on which way to go with a theater, what will be needed, etc. Speakers would probably be self designed, multichannel active, and may consider a large number of speakers in initial design to handle whatever combination of Auro or Atmos or Neo:X or whatever might come. Currently, that might even include something like the Lexicon QLi-32 taking digital outputs directly from source or perhaps modded pre-pro, directing sound to 11 ear level and 11 overhead for a 22.2 system. Crossovers would likely be digital whether accepting digital from QLi-32 or something else requiring ADC, with a resultant boatload of DAC's afterwards.
Processing, crossovers, and DAC's for that many channels are hard (and expensive) enough, but it's the volume control that surprisingly seems one of the bigger challenges. I'd very much like to avoid truncation from digital level control.
So... trying to get my head around options for a remotely operable multichannel analogue volume control options that can handle up to say 80 channels synchronously (!!!) to see if that path is feasible. No specific budget but that is a consideration in feasibility. Would prefer to keep to under a couple of thousand USD or would seriously consider other routes (as DACs, amp channels, and everything else would already be piling up). If not feasible, the other route is DAC and volume control in pre-pro on a more reasonable 8-12 channels, then ADCs, QLi-32 or similar, boatload of digital Xover and signal correction and then DACs. I know tests have shown an ADC/DAC loop can be sonically transparent but I worry about doing that to a highly attenuated signal (low volume level settings) where I insert lots of digital xover and other processing in the middle of the loops. Seems I'd want to maintain full level through processing if possible, not be manipulating the tiny extra noise from the ADC in the digital processing chain, etc...
The previously suggested MBS MVC seemed like it might fit the bill, $399 and could be cascaded, so perhaps $4K for 10 of them... but discontinued, and seems whatever stock is left is listed at $799.
The RDL RU-VCA6A is a VCA solution that can be cascaded, but at $450 or so each that's over $6K.
The BDI ACS-400 8 channel would probably work as it seems likely they could be synchronized, but at over $1300 each (>$13,000 total) that's out.
The SPL Volume8 isn't remotely controllable or cascadable that I can tell, and expensive.
Is the nuForce MCP-18 still available? Can't find much about this one.
Seems like a DIY approach might be needed, which I'm fine with, but would like to keep to prefabbed PCB's and maybe even pre-populated. Anyone know anything about the vicol audio R-2R kit solution? Remote?
Rod Elliot has a multichannel volume control based on VCA's, that seems like it could be expanded, but I'm guessing implementing a remote control might be difficult.
Any other suggestions? Something I've overlooked or not thinking about, like some cheapish studio or PA solution that could be made to work? Seems like the products offered are overpriced for what they are, especially ones that use a cheap IC and handful of analog components.
Finally getting house plans together (after a decade of medical school etc) and am just gathering thoughts on which way to go with a theater, what will be needed, etc. Speakers would probably be self designed, multichannel active, and may consider a large number of speakers in initial design to handle whatever combination of Auro or Atmos or Neo:X or whatever might come. Currently, that might even include something like the Lexicon QLi-32 taking digital outputs directly from source or perhaps modded pre-pro, directing sound to 11 ear level and 11 overhead for a 22.2 system. Crossovers would likely be digital whether accepting digital from QLi-32 or something else requiring ADC, with a resultant boatload of DAC's afterwards.
Processing, crossovers, and DAC's for that many channels are hard (and expensive) enough, but it's the volume control that surprisingly seems one of the bigger challenges. I'd very much like to avoid truncation from digital level control.
So... trying to get my head around options for a remotely operable multichannel analogue volume control options that can handle up to say 80 channels synchronously (!!!) to see if that path is feasible. No specific budget but that is a consideration in feasibility. Would prefer to keep to under a couple of thousand USD or would seriously consider other routes (as DACs, amp channels, and everything else would already be piling up). If not feasible, the other route is DAC and volume control in pre-pro on a more reasonable 8-12 channels, then ADCs, QLi-32 or similar, boatload of digital Xover and signal correction and then DACs. I know tests have shown an ADC/DAC loop can be sonically transparent but I worry about doing that to a highly attenuated signal (low volume level settings) where I insert lots of digital xover and other processing in the middle of the loops. Seems I'd want to maintain full level through processing if possible, not be manipulating the tiny extra noise from the ADC in the digital processing chain, etc...
The previously suggested MBS MVC seemed like it might fit the bill, $399 and could be cascaded, so perhaps $4K for 10 of them... but discontinued, and seems whatever stock is left is listed at $799.
The RDL RU-VCA6A is a VCA solution that can be cascaded, but at $450 or so each that's over $6K.
The BDI ACS-400 8 channel would probably work as it seems likely they could be synchronized, but at over $1300 each (>$13,000 total) that's out.
The SPL Volume8 isn't remotely controllable or cascadable that I can tell, and expensive.
Is the nuForce MCP-18 still available? Can't find much about this one.
Seems like a DIY approach might be needed, which I'm fine with, but would like to keep to prefabbed PCB's and maybe even pre-populated. Anyone know anything about the vicol audio R-2R kit solution? Remote?
Rod Elliot has a multichannel volume control based on VCA's, that seems like it could be expanded, but I'm guessing implementing a remote control might be difficult.
Any other suggestions? Something I've overlooked or not thinking about, like some cheapish studio or PA solution that could be made to work? Seems like the products offered are overpriced for what they are, especially ones that use a cheap IC and handful of analog components.
I'll boil it down to the simple question...
Thoughts on most cost effective sonically decent way to remotely control dozens of channels of line level analog volume attenuators synchronously?
Thoughts on most cost effective sonically decent way to remotely control dozens of channels of line level analog volume attenuators synchronously?
What kind of quality level do you have in mind? I guess that really boils down to what DACs will be directly in front of this multichannel volume control? A secondary question is what volume control range you're wanting?
Hi, thanks for responding. Yeah, a project with multiple chips would be fine... but I'd much much prefer a kit type project that included remote control, at least one that I could easily daisy chain or cascade multiple PCB's to get to the required channels. Haven't had a lot of luck coming up with anything.
Hi,
You're right RHosch, multichannel (>8ch) volume control isn't easy to find.
I've been down this road myself, I use PC/DSP based crossover and speaker management in my humble home theater. What I have found is that volume control before ADC seriously degrade SNR at moderate levels unless you have a very high spec ADC and DAC (SNR >120dB). Doing digital volume control is much easier you just need a high-spec multichannel DAC.
However the best solution is like you have described, to use an analog volume control between DAC and amplifiers. The best price/performance ratio per channel is achieved by using the PGA4311 or CS3318 chips even though they are not exactly cheap. Unfortunately not many boards are available with these (there is a 8ch PGA4311 board on ebay), and none of them can be daisy-chained even though both chips are designed with this in mind.
So what I did was to develop my own CS3318 based board that can easily be daisy-chained. It has an on-board microcontroller that takes RC5 remote codes and rotary encoder input, and drives a LED display. I have tested daisy-chaining just two boards for 16 channels, but it can in theory be expanded up to 128 * 8 = 1024 channels, which ought to be enough for anyone.
The rev-A boards had some mistakes so it required quite a few mods to be usable. So even though I have some spare boards I am a bit hesitant to sell these. If you were to make your own boards I could offer some advice, but it seems like you are more interested in ready-made PCBs. If there is enough interest I could consider making a rev-B version for a possible group-buy. I have a few ideas on how to improve on the design.
Br,
OJG
You're right RHosch, multichannel (>8ch) volume control isn't easy to find.
I've been down this road myself, I use PC/DSP based crossover and speaker management in my humble home theater. What I have found is that volume control before ADC seriously degrade SNR at moderate levels unless you have a very high spec ADC and DAC (SNR >120dB). Doing digital volume control is much easier you just need a high-spec multichannel DAC.
However the best solution is like you have described, to use an analog volume control between DAC and amplifiers. The best price/performance ratio per channel is achieved by using the PGA4311 or CS3318 chips even though they are not exactly cheap. Unfortunately not many boards are available with these (there is a 8ch PGA4311 board on ebay), and none of them can be daisy-chained even though both chips are designed with this in mind.
So what I did was to develop my own CS3318 based board that can easily be daisy-chained. It has an on-board microcontroller that takes RC5 remote codes and rotary encoder input, and drives a LED display. I have tested daisy-chaining just two boards for 16 channels, but it can in theory be expanded up to 128 * 8 = 1024 channels, which ought to be enough for anyone.
The rev-A boards had some mistakes so it required quite a few mods to be usable. So even though I have some spare boards I am a bit hesitant to sell these. If you were to make your own boards I could offer some advice, but it seems like you are more interested in ready-made PCBs. If there is enough interest I could consider making a rev-B version for a possible group-buy. I have a few ideas on how to improve on the design.
Br,
OJG
Cool, thanks....if you ever get around to a rev B and happen to remember this thread, shoot me a PM. I have 24 months or so before a room will even be complete so am just starting to get my head around potential problems and solutions. If I find no good solution for this one, I may have to take a different path up front.
And then this thread died…. I am looking for the same solution, albeit i only need 8 channels (4x2).