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Hackable AVR For Active Speakers?

JaredRad

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Does anyone know of any AVRs that are capable of being modified to use as an active crossover and amplifier? Here's what I want: a single box with a digital input and 6x or 8x amplifier outputs with individual DSP per-channel. I was thinking that AVRs have all of the components you'd need for such a device: multiple channels of amplification and programmable DSP. But any stock AVR firmware certainly wouldn't support arbitrary crossover and EQ per-channel, right? So has anyone ever heard of re-flashing a DSP in an AVR? Or are they generally somehow locked down to make that impossible? It's even somewhat hard to find detailed teardowns of AVRs to start to evaluate which brands/models may be more susceptible to modification. It would be great to discover a relatively low-cost AVR that could be hacked into a simple multi-way stereo amp.
 

MakeMineVinyl

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I have a feeling you're not going to find an AVR which would allow this with any reasonable amount of effort. Going the separates route would make much more sense. Alternately if your AVR has preamp outs, you could route this to an external active crossover, but I think this might still end up being a lot of trouble if you want to use the internal amps.
 
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JaredRad

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I have a feeling you're not going to find an AVR which would allow this with any reasonable amount of effort. Going the separates route would make much more sense.
That seems like the most likely outcome, but I thought I'd ask before I gave up on the idea. One plausible approach could be to use a computer to do the crossover and EQ in software, then real-time encode to some multichannel format over HDMI or S/PDIF that any AVR could ingest. The downsides I see are that 1) then you're going through the stock AVR processing, which may be pretty poor, and 2) it seems that 8 channel uncompressed audio (7.1) is the limit for most HDMI implementations (even though HDMI 2+ can do more) which limits it to a 3-way speaker (the .1 wouldn't be routable to an amplifier output).
 

Justin Zazzi

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This isn't exactly what you want, but it's close:
https://www.digikey.com/en/products/detail/analog-devices-inc/EVAL-ADAU1466Z/7915254

The ADAU1466 demo board has 4x analog inputs, 1x digital input, and 8x analog outputs. You can do literally anything in the DSP core using Sigma Studio. For <$200 it's an astonishingly powerful tool. You can also remote-wire a potentiometer to use as a volume control if you like, or use GPIO pins if you want to get fancy. Very simple to setup and use, however that blank canvas is a bit daunting because of all the possibilities.
 

Chrispy

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Closest avrs I can think of that provided an active crossover were the Onkyo 828/929....but that was only for a pair of two-ways.....but doubt you could hack them to use more....
 

16/44

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This isn't exactly what you want, but it's close:
https://www.digikey.com/en/products/detail/analog-devices-inc/EVAL-ADAU1466Z/7915254

The ADAU1466 demo board has 4x analog inputs, 1x digital input, and 8x analog outputs. You can do literally anything in the DSP core using Sigma Studio. For <$200 it's an astonishingly powerful tool. You can also remote-wire a potentiometer to use as a volume control if you like, or use GPIO pins if you want to get fancy. Very simple to setup and use, however that blank canvas is a bit daunting because of all the possibilities.

Very interesting. Could be useful when making the HiVi 3.1 kit towards becoming a fully active system.
 

andreasmaaan

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This isn't exactly what you want, but it's close:
https://www.digikey.com/en/products/detail/analog-devices-inc/EVAL-ADAU1466Z/7915254

The ADAU1466 demo board has 4x analog inputs, 1x digital input, and 8x analog outputs. You can do literally anything in the DSP core using Sigma Studio. For <$200 it's an astonishingly powerful tool. You can also remote-wire a potentiometer to use as a volume control if you like, or use GPIO pins if you want to get fancy. Very simple to setup and use, however that blank canvas is a bit daunting because of all the possibilities.

FWIW, Sigma Studio, which is Analog Devices' control software, is also excellent, and far more flexible than typical offerings aimed at the consumer market. However, it's also significantly harder to use.

Having said that, I think the OP was after not just a ADC-DSP-DAC, but also 6 or 8 amp channels, all in one unit.

In this case, I'd look in the direction of pro gear. For example, Crown DCi 8300DA, which I think retails for around $4k-$5k (so maybe a bit pricier than a typical AVR).
 
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JaredRad

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FWIW, Sigma Studio, which is Analog Devices' control software, is also excellent, and far more flexible than typical offerings aimed at the consumer market. However, it's also significantly harder to use.

Having said that, I think the OP was after not just a ADC-DSP-DAC, but also 6 or 8 amp channels, all in one unit.

In this case, I'd look in the direction of pro gear. For example, Crown DCi 8300DA, which I think retails for around $4k-$5k (so maybe a bit pricier than a typical AVR).

You’re correct, I was specifically thinking of a low-cost and low-fuss way to DIY an active system. Using separates is definitely a better route, but seems somewhat challenging to put together something halfway decent for under ~$1k or so (active xo + 6-8 channels of amplification), whereas AVRs with DSP and 7 or more channels of amplification can be had for ~<$500ish. If there were an AVR that could be reflashed with different firmware and maybe even a couple of easy hardware tweaks to make it a simple active crossover and amp that would be cool. It could open up active speakers to a whole new segment of people, both on price and convenience.

That Crown amp is definitely cool, but for $5k+ you could get 6-8 channels of purifi amp modules and a minidsp 4x10HD and a couple grand left over.
 

andreasmaaan

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You’re correct, I was specifically thinking of a low-cost and low-fuss way to DIY an active system. Using separates is definitely a better route, but seems somewhat challenging to put together something halfway decent for under ~$1k or so (active xo + 6-8 channels of amplification), whereas AVRs with DSP and 7 or more channels of amplification can be had for ~<$500ish. If there were an AVR that could be reflashed with different firmware and maybe even a couple of easy hardware tweaks to make it a simple active crossover and amp that would be cool. It could open up active speakers to a whole new segment of people, both on price and convenience.

That Crown amp is definitely cool, but for $5k+ you could get 6-8 channels of purifi amp modules and a minidsp 4x10HD and a couple grand left over.

Totally agree with that assessment.

If you're looking to cobble something together on a tight budget, Wondom does a 4-in 4-out DSP for $20 using an ADAU1701, plus plenty of 2-, 4- and 6-channel cheap chip amps, mostly based on TPA3116 and similar chips.

This would be kind of the opposite of what you asked about in your OP, ofc ;)
 

Plcamp

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The most annoying “feature” of my Yamaha RX-A3030 is the fact it will not provide a digital output that could be sent to an external dsp. (Ie you cannot output an SPDIF optical from an HDMI input signal).

So you cannot even use the AVR as a digital source selector into an external processor for things like biamping. Only the analogue pre-out is available.
 

maverickronin

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The most annoying “feature” of my Yamaha RX-A3030 is the fact it will not provide a digital output that could be sent to an external dsp. (Ie you cannot output an SPDIF optical from an HDMI input signal).

So you cannot even use the AVR as a digital source selector into an external processor for things like biamping. Only the analogue pre-out is available.

You can blame the movie cartels for that one.
 

Robovox

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Not quite what you wanted, but inexpensive and low fuss: you can pick up a 10-15 year old Arcam AVR 300 for under £200 - in UK at least - this has a 7.1 channel analogue input (RCA sockets). When this input is selected, the AV processing is all bypassed but you still have use of the master volume control. You could use any of the inexpensive DSP boards suggested above to implement the cross-over etc and then feed six channels (assuming a three-way ’speaker) into the AVR. Arcam claim 90W/ch with all 7 channels driven at 0.01% THD.

I have done something similar with a DIY active 2way - my Arcam 2ch integrated amp has a 7.1 preamp board fitted. I used an additional 2ch power amp for the tweeters. The was some hiss audible from the tweeter, which in my speakers was considerably higher sensitivity than the mid-bass so I used passive resistors to attenuate the tweeter output to match that of the mid bass. This rendered the hiss inaudible.
 

Chromatischism

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In theory you could make it work with an AVR...someone needs to write a modified or custom firmware like has been available for Canon Cameras for a long time. That way you could increase the available crossover frequency options, among other things. That's needed because the AVR operates as if each channel is going to a complete speaker. Then you might need to play with the stereo mix because it's programmed to play to specifically the L/R channel amps. Then you might run into issues if relays are in use. And many more complexities that are above my pay grade. But it's an interesting idea.
 

dougi

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Not quite what you wanted, but inexpensive and low fuss: you can pick up a 10-15 year old Arcam AVR 300 for under £200 - in UK at least - this has a 7.1 channel analogue input (RCA sockets). When this input is selected, the AV processing is all bypassed but you still have use of the master volume control. You could use any of the inexpensive DSP boards suggested above to implement the cross-over etc and then feed six channels (assuming a three-way ’speaker) into the AVR. Arcam claim 90W/ch with all 7 channels driven at 0.01% THD.

I have done something similar with a DIY active 2way - my Arcam 2ch integrated amp has a 7.1 preamp board fitted. I used an additional 2ch power amp for the tweeters. The was some hiss audible from the tweeter, which in my speakers was considerably higher sensitivity than the mid-bass so I used passive resistors to attenuate the tweeter output to match that of the mid bass. This rendered the hiss inaudible.
This is exactly what I do for the same application with a Denon AVR-2310 I picked up cheap. Similar power. Next trick is to try and fit the miniDSP nanodigi/Topping E30s/BT rx into the case.
 
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