I only know speakers as far as DIY competence goes so this can't be my project, but curious if the concept would make financial sense, and also if anyone else thinks it sounds good.
Reason I was thinking of this is that mid-to-high-end AVRs (consumer and pro) can be found cheap-to-free all over these days. Could a device like this be cheap enough to be worth buying for the approx. 100% discount on 7-8 channels of amp?
- It's a stand-alone board/box with up-to-date digital input options, input of which is converted/mixed to a digital 2-channel stereo bitrate and depth suitable for DSP.
- That digital stereo signal goes to a miniDSP type of EQ+xover with 3x2+1 output channels.
- Those 7 output channels are sent to an HDMI output that will be accepted by an outdated 7.1 AVR. Now we have everything to run 3-way DSP speakers and a DSP subwoofer channel, right?
Reason I was thinking of this is that mid-to-high-end AVRs (consumer and pro) can be found cheap-to-free all over these days. Could a device like this be cheap enough to be worth buying for the approx. 100% discount on 7-8 channels of amp?
I have done this with PC and EQ APO. Works, but can be tricky to get the signal through the AVR dsp unchanged.
You don't need hdmi do, AVR will mostly accept multichannel signal from spdif too.
Main problem is how to mix 6x I2S out of dsp signals into 1 spdif, properly so AVR reciver understands it. There must be chip for that somewhere....
On AVR's, usually you can run surround channels through only volume control, but front and center remain going through tone control chip. Depends on receiver. I use surround channels for mids as it is most critical. (I use analog multichannel inputs).
Easy option (as I do) is to have all signals converted by dacs (with multichannel soundcard (I use RME fireface) or dcx2496) . Then only volume control and power amps are utilized from AVR.
Main problem is how to mix 6x I2S out of dsp signals into 1 spdif, properly so AVR reciver understands it. There must be chip for that somewhere....
On AVR's, usually you can run surround channels through only volume control, but front and center remain going through tone control chip. Depends on receiver. I use surround channels for mids as it is most critical. (I use analog multichannel inputs).
Easy option (as I do) is to have all signals converted by dacs (with multichannel soundcard (I use RME fireface) or dcx2496) . Then only volume control and power amps are utilized from AVR.
S/PDIF without a codec is 2-channel (PCM). 6ch over S/PDIF requires a codec (AC3, DTS etc.) which makes it a proprietary thing and therefore trouble.
And AVRs usually do not accept 3 x S/PDIF.
Hi, you are right.
But I think there is no difference with HDMI connection neither. I think it is same SPDF signal is just added within multi-core HDMI (together with video and other protocols), or I got it wrong?
In any case, I believe as OP said that AVR that were popular 20 years ago are super available today. Using just power amps + volume control is worth it. All other boards could be removed providing the device still works (easy job, just unplug one after another that are not needed and see if main thing still works).
Final from my side, these AVR's also came in very different qualities. If already spending time , get higher class one, that was priced at least 1000€ at time when it was new.
Think we all agree that propriety protection built in these devices is pain and not worth fiddling for us. (for some people with different agenda probably it is, but that's not us)
Than again multichannel stream is available in pro gear (as I mentioned many sound-cards and dedicated XO DSP devices) that are also not very expensive and there the multichannel is opened and free to use, exactly what is needed for active speaker, and simple... we just feed AVR (or what is left of it after ditching unneeded parts) with analog signals.
Again, old AVR's , higher quality ones, still have pack of good power amps and sometimes very good chips for multichannel volume control. This is more than worth 100€ that one pays today for excellent AVR...
Some thoughts about that were recently typed here: https://www.diyaudio.com/community/...ve-and-seven-channel-amps.413824/post-7708021
Than again multichannel stream is available in pro gear (as I mentioned many sound-cards and dedicated XO DSP devices) that are also not very expensive and there the multichannel is opened and free to use, exactly what is needed for active speaker, and simple... we just feed AVR (or what is left of it after ditching unneeded parts) with analog signals.
Again, old AVR's , higher quality ones, still have pack of good power amps and sometimes very good chips for multichannel volume control. This is more than worth 100€ that one pays today for excellent AVR...
Some thoughts about that were recently typed here: https://www.diyaudio.com/community/...ve-and-seven-channel-amps.413824/post-7708021
No sure about proper licenses, but e.g. linux supports 6ch -> on-the-fly encoding AC3 for SPDIF to AVR (e.g. https://www.avnirvana.com/threads/hdmi-vs-spdif.14008/page-2#post-106318 )
When modding the AVR, the DSP board + I2S multich DACs could be placed directly into the AVR, using just the AVR's analog circuitry.
On a computer yes, Windows can do it as well e.g. AC3Filter, but the OP was talking chips ... Surprisingly in AC3Filter, HDMI is called SPDIF. A simple tick on SPDIF turns on the HDMI output (if available).
Last edited:
OK, I did not get this from his post.
IMO for the AC3Filter which needs only 2ch output HDMI and SPDIF are identical. Actually the 2ch HDMI audio stream is identical to SPDIF.
I was talking chips, yes, but I figured proprietary issues were likely and software is fine too.. The question with software I guess becomes what sort of very cheap options do we have for a computer that will do the 8-channel output to an old AVR? And, can we give it a digital input or does it have to become the source?
The 2ch source was just something I opened and AC3Filter's HDMI output is indeed 8ch PCM. The EQ / controls etc. are also 8 ch. The filters are FIR and gain / delay is adjustable across 8 channels.
👍
You just need a computer with an HDMI graphics card and since these licensed cards already have the proprietary HDMI magic built into them, there's no need for a separate licence to get it going. You could also run the video by using the passthrough feature in most AVRs.
The computer has been the source in my arrangements but someone here could know of ways to input something that I do not know of.
Sorry, I didn't read your post completely earlier.
It looks like maybe this setup https://www.minidsp.com/community/threads/minidigi-with-raspberry-pi-and-camilladsp.22531/ could work.