Minidsp 2x4HD and Marantz PM8005

[Huey2001]

Hi, can anyone advice on the use of a Minidsp 2x4HD for room correction, in combination with a Marantz PM8005?
I currently use (Focus Fidelity generated) convolution filters in Roon, that is connected via (Topping) DAC to the PM8005. I have an active subwoofer connected to the pre-amp of the PM8005.
This works great for the digital stream.
I would like however, to use the filter (in combination with the sub) also for analog cd and phono…
I read that it might be possible to connect the 2x4HD to the tape-out and tape-in, but I do not understand how that would work. Can someone explain that, if indeed possible, or maybe advice on how to do it otherwise?

(I do understand that the Minidsp Flex would allow you to use that as pre-amp for cd/phono, digital and sub, but it would also add a phono amp and I would like to reuse the PM8005 features as much as possible, also from a WAF point of view.)

Tia for any points of view

 

[Old_School_Brad]

The input/output you should use are these.
Pre out to miniDSP input.
miniDSP output to Power amp direct in.
Then you can keep the amplifier with your devices hooked up the way it is.

 

[Huey2001]

The input/output you should use are these.
Pre out to miniDSP input.
miniDSP output to Power amp direct in.
Then you can keep the amplifier with your devices hooked up the way it is.
View attachment 419578

Hi, ok thanks, but then where do I connect the subwoofer?

 

[staticV3]

Hi, ok thanks, but then where do I connect the subwoofer?

To the 2x4HD directly, or to the PM8005 Pre out in parallel to the 2x4HD.

 

[Huey2001]

To the 2x4HD directly, or to the PM8005 Pre out in parallel to the 2x4HD.

Ah, ok, that makes sense!

 

[staticV3]

Ah, ok, that makes sense!

Personally, I'd connect the sub to the 2x4HD.

Not only would that give me more fine-control as I could use the 2x4 for subwoofer integration, but I could also connect the PC to the 2x4 via USB and bypass the Topping DAC, PM8005, and 2x4HD's ADC for a higher fidelity signal.

 

[Huey2001]

Thanks for your suggestions,

Reading the Minidsp manual I now find however that I woulkd need to resize my filter...
The Minidsp only has room for 4090 taps in total for the 3 channels I would like/need to use (reserve 6 for the unused fourth). Looking at Roon it seems my filter now has 33k tabs...

How would I be able to bring the filter down to say 1024 per channel?
I assume I would then be able to load the minimized filter to Roon as well to get an impression on how it would sound?

 

[Huey2001]

Ok, reading on I guess this needs a completely different approach. Will stick with my current filter for now.

 

[Old_School_Brad]

Do you really need such a complex filter to achieve the sound you're looking for?

 

[Huey2001]

To be honest: I do not know. I have used umik-1 measurements with Focus Fidelity to generate it for room correction. I do perceive the sound as better.
No idea if and how I can replicate the correction with peq only or in combination with a less taps filter...?

 

[Joe Bloggs]

I read that it might be possible to connect the 2x4HD to the tape-out and tape-in, but I do not understand how that would work. Can someone explain that, if indeed possible, or maybe advice on how to do it otherwise?

If a tape out and a tape in exist, you would connect the input of the minidsp to the tape out and the minidsp output to the tape in. Then figure out how to have the system play from the tape in while continuing to route the phono input to the tape out.

But, why not just get a USB audio interface and plug the CD and phono outputs into that?

Would also be interested to look at the wav files generated by Focus Fidelity If nothing else you can always convert them to minimum phase for a short version

 

[Huey2001]

I enclosed the left and right filter (for 96K), so you can have a look and maybe tell how to convert?

 

[Joe Bloggs]

I enclosed the left and right filter (for 96K), so you can have a look and maybe tell how to convert?

Did you mean to crop it to 1024 taps at 96k or resample down to 48k first?

Is there a different limit at 96k vs 48k?

I would guess there's a longer size limit at 48k and, even the same length is worth more at 48k than at 96k.

(I never do convolution at anything above 48kHz)

 

[bmwr75]

The miniDSP 2x4HD has to be upgraded to do room correction with DIRAC Live or you can use REW to create EQ files and load them into the 2x4HD. I'm going on memory on that last REW part because it has been many years since upgrading my 2x4HD to a DDRC-24.

 

[Huey2001]

Did you mean to crop it to 1024 taps at 96k or resample down to 48k first?

Is there a different limit at 96k vs 48k?

I would guess there's a longer size limit at 48k and, even the same length is worth more at 48k than at 96k.

(I never do convolution at anything above 48kHz)

The minidsp makes use of 96k filters as I understand…
I read it is dangerous to “just” crop a convolution filter?

 

[Huey2001]

The miniDSP 2x4HD has to be upgraded to do room correction with DIRAC Live or you can use REW to create EQ files and load them into the 2x4HD. I'm going on memory on that last REW part because it has been many years since upgrading my 2x4HD to a DDRC-24.

Does the Dirac filter use more taps than the fir filter slots allow?
Maybe I should switch to using Dirac then…
Makes the experiment to be able to compare the result a bit complicated and costly though…

 

[Joe Bloggs]

The minidsp makes use of 96k filters as I understand…
I read it is dangerous to “just” crop a convolution filter?

Cropping them to 1024 at 96k is certainly a bit... .

You choose a range that captures most of the impulse's activity, then add some lead in and lead out. (see attached zip file)

At 1024 taps, you certainly can't expect results very very close to the original. This is what REW reckons the cropped impulse will "sound" like on one channel vs the original. The smoothed out trace is the cropped one

 

[bmwr75]

Does the Dirac filter use more taps than the fir filter slots allow?
Maybe I should switch to using Dirac then…
Makes the experiment to be able to compare the result a bit complicated and costly though…

I don't know the answer to your question. Dirac just works and takes up one of the 4 "profiles" you can access at any one time. Profiles may not be the right word.

 

[Huey2001]

Cropping them to 1024 at 96k is certainly a bit... .

You choose a range that captures most of the impulse's activity, then add some lead in and lead out. (see attached zip file)

At 1024 taps, you certainly can't expect results very very close to the original. This is what REW reckons the cropped impulse will "sound" like on one channel vs the original. The smoothed out trace is the cropped one
View attachment 421487

Hi, thanks for your efforts. Curious in how you have done the cropping.
I do notice the lows are now not included. I already read that the lows take up most taps, so that is probable why... (correct?).
Will give it a listen though.

 

[Huey2001]

I don't know the answer to your question. Dirac just works and takes up one of the 4 "profiles" you can access at any one time. Profiles may not be the right word.

Yeah, but maybe when going the Dirac route, I might be better of as to keep saving and replace the Marantz for maybe a NAD C397 (or if I hit some jackpot even a M10v3 when it finally support even DLBC then)...?