ASR Acourate users

[CK.]

You can use as many IIR allpass filters as you wish using biquads in miniDSP (can be designed in REW EQ) but they will all probably shift the phase in the opposite direction of what you really need. For time-inverted allpass filters, 2042 taps (not 2048) at 96kHz limits you to a min 47Hz frequency resolution and not much can be done in the region of interest even with rePhase optimization tricks.

In case of using IIR all-pass filters, what max Q would you recommend?

 

[john61ct]

2048 taps is too few to do anything meaningful. Opinions vary about how many taps you actually need, e.g. the author of LinFIR thinks that 16384 taps at 48kHz is enough (bin width = 48000/16384 = 2.9Hz) but Acourate typically uses 65536 taps at 48kHz (48000/65536 = 0.7Hz). MiniDSP typically has 2048 taps at 96kHz - which results in a bin width of 96000/2048 = 47Hz.

I wish I could make sense of those numbers, I did put that thread on my reading list.

What does the type of crossover have to do with amplifier count? We're talking likely over 12 channels here, most needing crossovers.

Using one amp per pair (not necessarily "stereo") or even mono one per channel is cheaper than big multichannel amps, and certainly more flexible.

I'm not considering AVRs if that's what you're referring to, bare power amps only.

if you have the budget for multiple amplifiers, a multichannel DAC, and some kind of computing device - it's DSP active XO all the way.

I don't.

Maybe a separate rPi convolver running each crossover will deliver enough taps, but that's not cheap.

or Wondom / Sure ADAU1701boards, or Dayton?

This looked sorta reasonable

ADAU1452-based "BEAYEAU" M26DSP from China, not cheap - any good?

M26DSP ADAU1452 Audio Processor 2 in 6 Out USB QCC3084 Bluetooth XLR/RCA Coaxial /fiber Input - https://a.aliexpress.com/_mKiL9Vj DSP noob here please ELI5 Use cases include crossovers, general PEQ, maybe non-automated room correction? Using REW + UMIK-2 for measuring... Yes I realise...

www.audiosciencereview.com

but sold out

 

[OCA]

In case of using IIR all-pass filters, what max Q would you recommend?

With IRR you will have no pre-ringing so sky is the limit but you would be adding more and more group delay

Actually, REW default 0.7071 (sqrt(2)/2 - Butterworth) is a good start. Some people prefer Bessel (0.577 for maximally flat group delay).

 

[3ll3d00d]

I wish I could make sense of those numbers, I did put that thread on my reading list.

bin width means frequency resolution, if you were drawing a curve then think of it as the points in the curve you can drag up and down. Now if those points are linearly spaced every 47Hz then that's basically completely useless at LF and totally fine at HF.

 

[pierre]

Great! In that case, a PC + interface is all that you need. Your choice of Roon / JRiver / Foobar2000 / Kodi / etc. + a convolver of your choice, all running on the same PC. Note that JRiver and Roon have built-in convolvers, but those are a bit basic. As for the interface, choose one from a reputable company (I recommend Motu or RME) that has as many output channels as you need.

The only question is whether Acourate is suitable for you. There are many options, Acourate is only one of them.

SotF has a convolver included too and it is free to play with

 

[john61ct]

Sons of the Forest?

 

[thcdru2k]

In case of using IIR all-pass filters, what max Q would you recommend?

I played with this in my Flex HTx setup. OCA’s 0.707 / 0.577 were great starting points, in my room the broad issue around 44 Hz measured best with Q0.5 on the right sub.

After that I still had a smaller weakness around the upper-50s, so I added a second AP at 56 Hz Q2.0. My thinking was the first AP was a broad low-bass phase correction, while the second needed to be more localized since it was closer to the main/sub overlap region.

With the APs off, the 25–45 Hz region loses a lot of foundation. With them on, low-bass summation comes back while the 60–100 Hz region stays mostly intact.

Acourate looks powerful, but for HDMI/movie use with the Flex HTx, I think I’m mostly limited to IIR/biquad tools unless I move processing upstream to a PC/convolver. The important thing I learned was lot of trial and error because applying the same AP filter to different sub one at a time creates different results. I'm still learning / experimenting.


Before two all pass filters no other changes to delay, crossover, PEQ

After just AP 44hz Q.5 and 56Hz Q2.0

 

[CK.]

I played with this in my Flex HTx setup. OCA’s 0.707 / 0.577 were great starting points, in my room the broad issue around 44 Hz measured best with Q0.5 on the right sub.

After that I still had a smaller weakness around the upper-50s, so I added a second AP at 56 Hz Q2.0. My thinking was the first AP was a broad low-bass phase correction, while the second needed to be more localized since it was closer to the main/sub overlap region.

With the APs off, the 25–45 Hz region loses a lot of foundation. With them on, low-bass summation comes back while the 60–100 Hz region stays mostly intact.

Acourate looks powerful, but for HDMI/movie use with the Flex HTx, I think I’m mostly limited to IIR/biquad tools unless I move processing upstream to a PC/convolver. The important thing I learned was lot of trial and error because applying the same AP filter to different sub one at a time creates different results. I'm still learning / experimenting.


Before two all pass filters no other changes to delay, crossover, PEQ
View attachment 536863

After just AP 44hz Q.5 and 56Hz Q2.0
View attachment 536864

Thanks for sharing. I found that AP with Q<1 is not surgical enough and affects a broad range of feequencies and sometimes you end up playing whacamole. Sometimes you get lucky though.

Btw your HF seem elevated, is that by choice?

 

[thcdru2k]

Thanks for sharing. I found that AP with Q<1 is not surgical enough and affects a broad range of feequencies and sometimes you end up playing whacamole. Sometimes you get lucky though.

Btw your HF seem elevated, is that by choice?

Yeah, partly by choice. I’m mostly using DSP to fix bass integration, some room issues, not to flatten the whole in-room trace.

The top end doesn’t bother me in actual listening, so I’ve left that voicing alone for now.

 

[Keith_W]

I have been given permission by Uli to talk about this, so here we are. There will be a new version of Acourate available soon. It has a more robust pre-ringing compensation feature which is built into Macro 4.

Uli asked me to use Excessphase compensation of 6/6 which uses a longer window - but this significantly increases the risk of pre-ringing. He then asked me to compare EP 6/6 of the old version to the new version.

In green is the old version of Acourate (v.3.1.7), and in red is the new yet-to-be-released version (v3.3.2). That's pretty remarkable! Uli said that he has been searching for this solution for many years.

Because of the increased resistance to pre-ringing, this new version should allow users to be a bit more adventurous with filters that normally create a lot of pre-ringing. Like high Q filters, asymmetric slopes, aggressive corrections, etc. Indeed the ICPA (interchannel phase alignment) feature can now be used with higher Q's.

 

[CK.]

I have been given permission by Uli to talk about this, so here we are. There will be a new version of Acourate available soon. It has a more robust pre-ringing compensation feature which is built into Macro 4.

Uli asked me to use Excessphase compensation of 6/6 which uses a longer window - but this significantly increases the risk of pre-ringing. He then asked me to compare EP 6/6 of the old version to the new version.

View attachment 542197

In green is the old version of Acourate (v.3.1.7), and in red is the new yet-to-be-released version (v3.3.2). That's pretty remarkable! Uli said that he has been searching for this solution for many years.

Because of the increased resistance to pre-ringing, this new version should allow users to be a bit more adventurous with filters that normally create a lot of pre-ringing. Like high Q filters, asymmetric slopes, aggressive corrections, etc. Indeed the ICPA (interchannel phase alignment) feature can now be used with higher Q's.

Great! Thanks for sharing.

Do you know how we can get this new version after releasing?

 

[Salt]

Great! Thanks for sharing.

Do you know how we can get this new version after releasing?

Download?

 

[markstein]

Great! Thanks for sharing.

Do you know how we can get this new version after releasing?

Usually you need to contact Uli per email and he will send you a download link.