Is it smart to use MiniDSP 2x4HD for DSP/FIR/convolution in an Atmos/Auro3D setup?

[baron-bob]

Hello,
I'm planing my Home-cinema right now and have a question about a general approach to it in regards of digital room correction.

I'm using for all media application my Windows 10 PC (Music, Movie, Games) and got a 8500HA, 3x ROTEL 1506, passive speakers Auro3D 13.1 setup, 4 sub's and one MiniDSP. I'm also a huge fan of Auro3D and want to use it through my AVR.

Recently I found this awesome YouTube channel of "Obsessive Compulsive Audiophile" (OCA) which in my opinion really sticks out because of the in-depth technical and scientific content and practical application of DSP filter creation and convolution. He is also a member of the forum here. I'm already working with REW and MSO and a MiniDSP for my four sub's, so I'm not completly new to the topic of MiniDSP. But I never touched the topics before that OCA is covering in his videos. Now that I got a glimpse of that I would like to know what would be the best approach to implement this to my future setup? Or in other words what would be the best approach that I could integrate with my gear?

I'm thinking about getting 7 MiniDSP 2x4HD to apply convolution filters to each of my channels of my Auro3D 13.1 setup, but I don't know if this is the only or the best way to do this?

Right now I did not had the time to really dive into the content of OCA's channel but I will in the future and probably will try everything out with EQ APO for stereo and 7.1 but I would also like to know if there are even more "things" to take into account apart from phase correction, delay, output-response EQ, crossover phase matching and gain matching for a channel that would be possible to do with a miniDSP or that professionals do in home-cinema building but that I also could do, if I put the work in it?

Thanks for your answers!

 

[TheBatsEar]

Recently I found this awesome YouTube channel of "Obsessive Compulsive Audiophile" (OCA)

I'll look into it as well, let's see what i can learn. So far i really just reduced the tops of my room modes below Schroeder frequency.

I'm thinking about getting 7 MiniDSP 2x4HD to apply convolution filters to each of my channels of my Auro3D 13.1 setup, but I don't know if this is the only or the best way to do this?

That sure sounds ambitious!

 

[voodooless]

I really don’t see too much of a point. You already have room correction with Audyssey, and can use the companion app to tune the system. It will also do convolution…

MiniDSP for the subs may make sense, results of Audyssey sub optimization can be all over the place.

You could also go for a new Denon AVR and wait for Dirac ART to be supported. That will bring it to the next level as well, and is probably a cheaper option.

 

[kemmler3D]

I really don’t see too much of a point. You already have room correction with Audyssey, and can use the companion app to tune the system. It will also do convolution…

MiniDSP for the subs may make sense, results of Audyssey can be all over the place.

You could also go for a new Denon AVR and wait for Dirac ART to be supported. That will bring it to the next level as well, and is probably a cheaper option.

If you can splash out for 7 MiniDSPs then I agree waiting for Dirac ART unit would be a much better option. It's going to automate processes that are very beneficial, and would be difficult and painful by hand with a MiniDSP unit.

 

[baron-bob]

I really don’t see too much of a point. You already have room correction with Audyssey, and can use the companion app to tune the system. It will also do convolution…

MiniDSP for the subs may make sense, results of Audyssey sub optimization can be all over the place.

You could also go for a new Denon AVR and wait for Dirac ART to be supported. That will bring it to the next level as well, and is probably a cheaper option.

Thanks for your reply voodooless.

AFAIK ART for people that can not afford 15-18k for a preamp (Stormaudio) is far beyond the horizon and it is only effective up to ~200hz. So I'm not sure if it is worth the waiting. Also 7 miniDSP come for 1800€ at most (I will look for used ones and got just one today for 176€) I can not see that an upgrade to a new ART AVR will cost me less. Even the AH1 is probably not capable of an ART update and it will take some time until the next top model will come around.

AFAIK Audyssey is not correcting phase or groupdelay. Also AFAIK all AVR's until today have not precise delay settings. Even if you can change the distance in 1cm increments it only changes the actual delay every 3-5 increments in relatively big steps. Also if I'm using miniDSP for my sub's it introduces a delay that can not be compensated with the settings within the Denon because it has this 6m limit between individual speakers. Since I'm very pleased with MSO there is no way back from that for me.

AFAIK right now convolution is a tool which gives us the ability to create several different filters (e.g. group-delay, excess-phase, impulse-response, crossover, crossover phase, ?perhaps even some other useful ones?) and combine them into one FIR filter. It seems to me that the methods OCA uses in his tutorials are supperior to Audyssey or Dirac. It has a step learning curve, but it is no magic and I think, after one has experience with it it is not that hard. Of course it is some work but it is a hobby so not really work ; ) So I do not want to do convolution and FIR for the sake of convolution and FIR but a better one than Audssey or Dirac does.

Here they talk about what I would like to do in the end

Of course I have passive speakers but OCA explains how to apply crossover phase correction not only to the sub but also to passive speakers.

Please correct me if anything is wrong what I wrote and point me to sources to learn from.

 

[ernestcarl]

7 miniDSP come for 1800€ at most (I will look for used ones and got just one today for 176€) I can not see that an upgrade to a new ART AVR will cost me less. Even the AH1 is probably not capable of an ART update and it will take some time until the next top model will come around

AFAIK right now convolution is a tool which gives us the ability to create several different filters (e.g. group-delay, excess-phase, impulse-response, crossover, crossover phase, ?perhaps even some other useful ones?) and combine them into one FIR filter. It seems to me that the methods OCA uses in his tutorials are supperior to Audyssey or Dirac.

It's only better if you know what you are doing, and are actually able to get better results than the more semi-automated procedure with Audyssey/Dirac.

@gnarly suggested in another thread searching ebay for used QSC 110f processors -- not sure what the max tap limit is per channel, but it's very likely more than what's available with the 2x4HD.

 

[baron-bob]

It's only better if you know what you are doing, and are actually able to get better results than the more semi-automated procedure with Audyssey/Dirac.

@gnarly suggested in another thread searching ebay for used QSC 110f processors -- not sure what the max tap limit is per channel, but it's very likely more than what's available with the 2x4HD.

Valid point. It will be probably a hermeneutical process ; )

Thanks for the tip about the 110f. I will look into it but daaaaamn it is expensiv. Not sure if even a used one will be less than 3000€ and perhaps it will take an extra license for FIR support.

 

[ernestcarl]

Valid point. It will be probably a hermeneutical process ; )

Thanks for the tip about the 110f. I will look into it but daaaaamn it is expensiv. Not sure if even a used one will be less than 3000€ and perhaps it will take an extra license for FIR support.

Might depend on where you live but a quick glance for me:

That's actually pretty reasonable for used gear... occasionally sellers will reach out privately to reduce the price. That's sometimes how I get cheaper prices for my audio stuff.

Eh, also I don't really think you need to pay extra to use FIR filtering in these units.

 

[baron-bob]

not sure what the max tap limit is per channel, but it's very likely more than what's available with the 2x4HD.

The number of tabs being used is directly related with the delay that is introduced by the filter right? Can you tell me what the delay will be if all tabs of the 2x4HD are used? It has ~4000 and it would ~2000 for each channel when utilized for two channels?

 

[kemmler3D]

You have a point on ART vs. DIY and $$$... but it will be a lot of work.

I haven't attempted all of these correction techniques myself, but they should all be doable to an extent. However, correcting crossover phase and things like that are tricky to the extent that getting really good measurements is tricky. Not hard by any means but lots of things can go wrong with the measurements.

Other adjustments may not be "juice worth the squeeze" type of changes. For example, adjusting delay isn't hard, but in a room that's less than 20 feet across it is going to be hard to notice. EQ above Schroeder demands that you have full quasi-anechoic on- and off-axis measurements of your speakers so you can be sure you're making things better and not worse. Fixing crossover phase might actually be beneficial, but again, measurements need to be good, and maybe the phase is a little off on purpose to correct something about the FR. Designers do all kinds of wacky stuff with passive crossovers. Also, the difference between perfect and okay phase response is hard to hear.

If you want to go extremely hard, you can do something ART-like by using surround channels for active cancellation of modes/reflections in the MLP. There's no reason in theory you can't do it manually, it will probably just take a lot of work and experimentation. It will also stop working if you move your speakers.

All that said I fully support going after these tweaks and posting your measurements and impressions.

 

[baron-bob]

Might depend on where you live but a quick glance for me:

View attachment 311869

That's actually pretty reasonable for used gear... occasionally sellers will reach out privately to reduce the price. That's sometimes how I get cheaper prices for my audio stuff.

Eh, also I don't really think you need to pay extra to use FIR filtering in these units.

I'm from Germany. I could get one for 2500€ from GB it seems. It would be nice to have only one device tough....

 

[ernestcarl]

The number of tabs being used is directly related with the delay that is introduced by the filter right? Can you tell me what the delay will be if all tabs of the 2x4HD are used? It has ~4000 and it would ~2000 for each channel when utilized for two channels?

If you use miniDSP's max ~4k taps the overall delay/processing latency would be above 20 ms:

rePhase

You could change some of the parameters to get near 0 ms of delay -- say, if limiting use for minimum phase only EQ, for example:

 

[baron-bob]

If you use miniDSP's max ~4k taps the overall delay/processing latency would be above 20 ms:

rePhase
View attachment 311871


You could change some of the parameters to get near 0 ms of delay -- say, if limiting use for minimum phase only EQ, for example:

View attachment 311872 View attachment 311873

Thanks that was very helpful! Because I also use my system for gaming it would be a really annoying if the delay would be over 100ms or so.

 

[ernestcarl]

Thanks that was very helpful! Because I also use my system for gaming it would be a really annoying if the delay would be over 100ms or so.

I don't game... however, 21ms for me is imperceptible when it comes to lip sync with movie playback e.g. Netflix and Youtube -- since you also have processing delay in the video chain stream anyway (e.g. some monitor models more than others).

 

[baron-bob]

You have a point on ART vs. DIY and $$$... but it will be a lot of work.

I haven't attempted all of these correction techniques myself, but they should all be doable to an extent. However, correcting crossover phase and things like that are tricky to the extent that getting really good measurements is tricky. Not hard by any means but lots of things can go wrong with the measurements.

Other adjustments may not be "juice worth the squeeze" type of changes. For example, adjusting delay isn't hard, but in a room that's less than 20 feet across it is going to be hard to notice. EQ above Schroeder demands that you have full quasi-anechoic on- and off-axis measurements of your speakers so you can be sure you're making things better and not worse. Fixing crossover phase might actually be beneficial, but again, measurements need to be good, and maybe the phase is a little off on purpose to correct something about the FR. Designers do all kinds of wacky stuff with passive crossovers. Also, the difference between perfect and okay phase response is hard to hear.

If you want to go extremely hard, you can do something ART-like by using surround channels for active cancellation of modes/reflections in the MLP. There's no reason in theory you can't do it manually, it will probably just take a lot of work and experimentation. It will also stop working if you move your speakers.

All that said I fully support going after these tweaks and posting your measurements and impressions.

Thank you very much. I was looking for these kind of reply's which give me a better general understanding of the matter and what to take into account.

I will surely share my experiences here in the forum.

 

[voodooless]

All the things described are things Audyssey or Dirac already do for you with the press of a button. ART goes even way beyond that below 200 Hz. And you don’t have to buy a $15k Sormaudio either. Basically every recent Denon model >= X3800H will get it by the end of the year.

 

[baron-bob]

All the things described are things Audyssey or Dirac already do for you with the press of a button. ART goes even way beyond that below 200 Hz. And you don’t have to buy a $15k Sormaudio either. Basically every recent Denon model >= X3800H will get it by the end of the year.

I got your point but by what I know at the moment Audyssey falls completly out of the picture right know because it is only working in the frequenzy domain. I have MultEQX right now but only use it for mains till 400Hz because it makes things worse and for the subs MSO which is fantastic. Dirac is better in this regard because it also works in the phase domain.

I'm still convinced that manual filter creation as described by OCA is better and achivable by me.

I did not know about the rumors for ART coming to Denon, thanks for the tip, by the end of this year but I still would not bet on it. As I understand they still in developing stage and it has to play out first if they can really integrate it in there current hardware.

But even if, there is still the price tag. The only alternativ for me from Denon would be the A1H > at least 3000€ if I sell my 8500HA and not really much in there that would be relevant for me in comparison to the 8500HA. Marantz has the AV8805A and the AV10 > same there and the license for ART will also come around 1000€ and is connected with the device.

Everybody has his own priority's. A good reason for me to get a new receiver or pre-amp would be a new Auromatic version with front wide support or something like that. I like to tinker a bit so manual calibration is not a problem for me and it gives me options that Dirac do not offer at the moment. If they improve there room correction (e.g > 200Hz) in a way as ART in the future, then I will surly get it at some point and with a device that is a real upgrade for my needs. Or I get filthy rich by accident and can afford a Trinnov some day ; )

I think a proprietary solution with separate DSP and is the best choice for me right now. I will look more into the Core 110f as ernestcarl recommended. So if you have some ideas besides automated systems feel free to point me in that direction.

With best regards

Frank

 

[voodooless]

I got your point but by what I know at the moment Audyssey falls completly out of the picture right know because it is only working in the frequenzy domain.

No, it does not work only in the frequency domain.

 

[baron-bob]

No, it does not work only in the frequency domain.

That would be in contrast what is stated by OCA here which I fully trust in regards of his expertise. Please feel free to point me to a source which describes and explains how to get better results with Audyssey than with manual calibration as described by OCA. If there is a way or method I would gladly adapt it. If you like you could also point out other misinformation from his videos. I'm happy for any technical expertise that is contributed to this tread.
Thanks

 

[voodooless]

Well, the computer voice is wrong

Both Dirac and Audyssey use mixed IIR and FIR filters. Granted, Audyssey filters are more limited. Still, both can and will do time domain corrections.

Here are some pointers for better correction with Audyssey:

Configuring Audyssey – The Right Way

Find out how to get the best out of you Audyssey receiver in this article by configuring Audyssey the Right Way!

simplehomecinema.com

And:

Audyssey – Simple Home Cinema

Posts about Audyssey written by Roland

simplehomecinema.com