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Can I load my own FIR filter into the SHD? 1 year 4 months ago #48024

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Can anyone send me a copy if his Dirac generated file (for SHD)?
Maybe I can look into it and find out the format.

If you don't have an SHD your questions do rather beg the question of why you are interested in this? In that if you don't want to use Dirac it might be that a different product is more suited to you? Although having said that I did buy an SHD without really wanting Dirac...


Ok, there it goes:

Currently I have a 5.2 setup around an Marantz AV8805 using Audyssey.
The mains are electrostatics combined with a SVS for <125Hz.
I now use the SVS DSP for xover. Its noisy, I have doubts in the signal path quality of the SVS for fullrange.
So the SHD would replace the xover and would add Dirac for stereo listening.
I am confident that the SHD will be enough high quality signal wise. (Transparent)
But I dont want to lose my HT functionality.
This seems to be only possible if the latency of the SHD is low enough.
So I hope this explains my reasoning in wanting to have a solution for a lower latency SHD. :)

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Can I load my own FIR filter into the SHD? 1 year 4 months ago #48025

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Can anyone send me a copy if his Dirac generated file (for SHD)?
Maybe I can look into it and find out the format.

If you don't have an SHD your questions do rather beg the question of why you are interested in this? In that if you don't want to use Dirac it might be that a different product is more suited to you? Although having said that I did buy an SHD without really wanting Dirac...


Ok, there it goes:

Currently I have a 5.2 setup around an Marantz AV8805 using Audyssey.
The mains are electrostatics combined with a SVS for <125Hz.
I now use the SVS DSP for xover. Its noisy, I have doubts in the signal path quality of the SVS for fullrange.
So the SHD would replace the xover and would add Dirac for stereo listening.
I am confident that the SHD will be enough high quality signal wise. (Transparent)
But I dont want to lose my HT functionality.
This seems to be only possible if the latency of the SHD is low enough.
So I hope this explains my reasoning in wanting to have a solution for a lower latency SHD. :)


Subwoofer integration is the most powerful capability of miniDSPs for stereo use for me and is why I use them.

Have you checked the spec of your AVR to know that the latency of the SHD will be a problem?

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Can I load my own FIR filter into the SHD? 1 year 4 months ago #48026

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Can anyone send me a copy if his Dirac generated file (for SHD)?
Maybe I can look into it and find out the format.

If you don't have an SHD your questions do rather beg the question of why you are interested in this? In that if you don't want to use Dirac it might be that a different product is more suited to you? Although having said that I did buy an SHD without really wanting Dirac...


Ok, there it goes:

Currently I have a 5.2 setup around an Marantz AV8805 using Audyssey.
The mains are electrostatics combined with a SVS for <125Hz.
I now use the SVS DSP for xover. Its noisy, I have doubts in the signal path quality of the SVS for fullrange.
So the SHD would replace the xover and would add Dirac for stereo listening.
I am confident that the SHD will be enough high quality signal wise. (Transparent)
But I dont want to lose my HT functionality.
This seems to be only possible if the latency of the SHD is low enough.
So I hope this explains my reasoning in wanting to have a solution for a lower latency SHD. :)


Subwoofer integration is the most powerful capability of miniDSPs for stereo use for me and is why I use them.

Have you checked the spec of your AVR to know that the latency of the SHD will be a problem?


Yes, maximum difference between channels should be below 6 meters, so around 17 msec.

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Can I load my own FIR filter into the SHD? 1 year 4 months ago #48027

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My recollection from reading the Dirac technical papers is that they don't use FIR filters, that's is somewhat old-fashioned and what competitors use to lesser effect. Dirac term their filters mixed-phase and I beleve they use their own filter structure. That structure and the coefficients that go in it are their crown jewels. Even if you could extract their coefficents from files it likely wouldn't help you.

The other point is that I'm not sure anybody has ever measured the latency of an SHD. I use one for live recording in Ableton Live and haven't noticed excess latency and I am normally sensitive to anything above 15ms. I know various figured have been mentioned but I'm not convinced any of them are authorative.

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Can I load my own FIR filter into the SHD? 1 year 4 months ago #48028

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My recollection from reading the Dirac technical papers is that they don't use FIR filters, that's is somewhat old-fashioned and what competitors use to lesser effect. Dirac term their filters mixed-phase and I beleve they use their own filter structure. That structure and the coefficients that go in it are their crown jewels. Even if you could extract their coefficents from files it likely wouldn't help you.

The other point is that I'm not sure anybody has ever measured the latency of an SHD. I use one for live recording in Ableton Live and haven't noticed excess latency and I am normally sensitive to anything above 15ms. I know various figured have been mentioned but I'm not convinced any of them are authorative.


Indeed if the Dirac is that secretive about the resulting filters it might be impossible to get my idea working :(

About the latency:

A direct question to miniDSP gave 23msec as latency.
On audioscience.com there was a member who said he measured it himself at 25msec.

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Can I load my own FIR filter into the SHD? 1 year 4 months ago #48029

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My recollection from reading the Dirac technical papers is that they don't use FIR filters, that's is somewhat old-fashioned and what competitors use to lesser effect. Dirac term their filters mixed-phase and I beleve they use their own filter structure. That structure and the coefficients that go in it are their crown jewels. Even if you could extract their coefficents from files it likely wouldn't help you.

The other point is that I'm not sure anybody has ever measured the latency of an SHD. I use one for live recording in Ableton Live and haven't noticed excess latency and I am normally sensitive to anything above 15ms. I know various figured have been mentioned but I'm not convinced any of them are authorative.


Indeed if the Dirac is that secretive about the resulting filters it might be impossible to get my idea working :(

About the latency:

A direct question to miniDSP gave 23msec as latency.
On audioscience.com there was a member who said he measured it himself at 25msec.


I did some reading and now see the Dirac is a propriety solution and openDRC is completely open.
So conclusion could be I need an SHD with openDRC..

@miniDSP support: is it possible to have a openDRC version of the SHD? That seems like a nice addition to the SHD Dirac product.

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Last edit: by mvs0.

Can I load my own FIR filter into the SHD? 1 year 4 months ago #48030

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My recollection from reading the Dirac technical papers is that they don't use FIR filters, that's is somewhat old-fashioned and what competitors use to lesser effect. Dirac term their filters mixed-phase and I beleve they use their own filter structure. That structure and the coefficients that go in it are their crown jewels. Even if you could extract their coefficents from files it likely wouldn't help you.


I nearly made this point myself actually but given that both Dirac filters and traditional FIR filters are both used to adjust phase there is at least a good deal of commonality. My hunch is that both are stored as a set of values, one for each 'tap' and so may be interchangeable. Note also that if a 2x4 HD is 'upgraded' to a DDRC-24 the FIR capability of the original is replaced with Dirac functionality.

I still think all this is moot since even if the file could be found and edited I'm doubtful it could be sent on to the SHD.

Stereo music is my top priority and for blu-ray playback I accept that whilst I have got the mains and sub in phase there is a 1-cycle lag of the sub vs the mains. This really isn't noticeable, and not that this is the sort of thing everyone was doing before AVRs allowed main speaker signals to be delayed. Good phase matching is more important than perfect first arrival matching I think.

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Last edit: by Ultrasonic.

Can I load my own FIR filter into the SHD? 1 year 4 months ago #48031

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My recollection from reading the Dirac technical papers is that they don't use FIR filters, that's is somewhat old-fashioned and what competitors use to lesser effect. Dirac term their filters mixed-phase and I beleve they use their own filter structure. That structure and the coefficients that go in it are their crown jewels. Even if you could extract their coefficents from files it likely wouldn't help you.


Stereo music is my top priority and for blu-ray playback I accept that whilst I have got the mains and sub in phase there is a 1-cycle lag of the sub vs the mains. This really isn't noticeable, and not that this is the sort of thing everyone was doing before AVRs allowed main speaker signals to be delayed. Good phase matching is more important than perfect first arrival matching I think.


So how is your HT+stereo wired up?
You use an SHD for mains and still have the subs on the AVR?

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Can I load my own FIR filter into the SHD? 1 year 4 months ago #48032

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So how is your HT+stereo wired up?
You use an SHD for mains and still have the subs on the AVR?


I don't own an AVR and so run a 2.1 system for blu-ray playback using analogue outputs from my OPPO player. As I said, stereo music is my priority.

I actually realised that I now could in principle sort out the time delay issue for blu-ray playback since I am using a 2x4 HD on the sub channel and an SHD on the left and right main speaker channels. But doing so may well cause lip sync issues. For now all I do is use the 2x4 HD to EQ the sub with the OPPO providing the crossover and my SHD applying no processing. Volume control is via the OPPO.

I wouldn't particularly recommend this approach to anyone. I upgraded from the 2x4 HD to the SHD and realised I could use my original miniDSP this way.

For stereo music my system is:

SHD -> Bel Canto eVo 4 power amp -> Meadowlark Shearwater HotRod main speakers
______-> Power Sound Audio S1510 subwoofer

For blu-ray playback my system is:

OPPO BDP 83: L + R -> SHD -> Power amp -> Main speakers
_________________Sub channel -> 2x4 HD -> Subwoofer
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Last edit: by Ultrasonic.

Can I load my own FIR filter into the SHD? 1 year 4 months ago #48050

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I have now tracked down where my Dirac projects are saved but they aren't in a simple text format and so not something I can see an easy way of opening outside of the Dirac Live application. As I said earlier I'm not sure this will include the actual filter data anyway.

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Can I load my own FIR filter into the SHD? 1 year 4 months ago #48051

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And as I understand it, SHD has same latency whether Dirac is turned on or off, so the latency isn't due to Dirac, even though it requires it for lookahead to deal with non-minimal phase room effects.

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Can I load my own FIR filter into the SHD? 1 year 4 months ago #48052

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And as I understand it, SHD has same latency whether Dirac is turned on or off, so the latency isn't due to Dirac, even though it requires it for lookahead to deal with non-minimal phase room effects.


Or the latency with Dirac off is deliberately but unecessarily made to match that with Dirac on. I think this is what the OP was thinking may be the case, which seems possible to me. I don't see any way round it though!

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Can I load my own FIR filter into the SHD? 1 year 4 months ago #48053

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And as I understand it, SHD has same latency whether Dirac is turned on or off, so the latency isn't due to Dirac, even though it requires it for lookahead to deal with non-minimal phase room effects.


Or the latency with Dirac off is deliberately but unecessarily made to match that with Dirac on. I think this is what the OP was thinking may be the case, which seems possible to me. I don't see any way round it though!


Yes, the OP was under the impression that it might be possible to tweak the Dirac filter coefficients to remove the latency. I guess they've done it this way to avoid objectionable 23ms glitches when turning Dirac on and off. That is quite long for a glitch. If instead they had used a 23ms mute music rhythm would change slightly when turning Dirac on and off which is also rather objectionable. Still, I can quite understand that a permanent 23ms latency causes huge issues for some applications.

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Can I load my own FIR filter into the SHD? 1 year 4 months ago #48057

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I have now tracked down where my Dirac projects are saved but they aren't in a simple text format and so not something I can see an easy way of opening outside of the Dirac Live application. As I said earlier I'm not sure this will include the actual filter data anyway.


Could you share these files with me so I can take a look?

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Can I load my own FIR filter into the SHD? 1 year 4 months ago #48061

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Could you share these files with me so I can take a look?


I could but actually I won't because @Devteam may prefer I didn't and I really think they would be completely useless to you anyway. I doubt they include Dirac filters (as there is no need for them to) and even if they did I don't think you could upload an amended filter to an SHD.

You could try contacting support directly if you haven't already.

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Last edit: by Ultrasonic.
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