I know, I know...Apodizing Filter

[DimitryZ]

I have an MQA DAC - M2TECh Young III, and an non MQA modern DAC - Topping D70. On the same material available on Tidal as MQA and on Qobuz as hires, these both sound VERY similar if the low dispersion filter is enabled on rhe D70. My understanding is the low dispersion filter is the MQA apodizing filter, which pushes all the ringing to the right in the time domain.

Comments? Opinions?

 

[garyi]

I recognise half of those words.

 

[david ellwood]

I have similar options on my D33 and find the apodising filter to be the most analogue sounding.

it’s not a subtle difference but hard to choose as so much changes about the presentation.

 

[tuga]

I have an MQA DAC - M2TECh Young III, and an non MQA modern DAC - Topping D70. On the same material available on Tidal as MQA and on Qobuz as hires, these both sound VERY similar if the low dispersion filter is enabled on rhe D70. My understanding is the low dispersion filter is the MQA apodizing filter, which pushes all the ringing to the right in the time domain.

Comments? Opinions?

MQA is the new MP3. With DRM.

Always Discreet underpants, all the freedom you need to enjoy MQA's leeky filter.

 

[tuga]

Discussion on the MQA filter (and filters in general)... [Update: Including a look at the classic "Apodizing" filter.]

http://archimago.blogspot.com/2017/02/musings-discussion-on-mqa-filter-and.html?m=1

 

[Jim Audiomisc]

This thread caused me to recall a recent one about MQA not having posted their company returns a while ago. However I couldn't refind that thread using the forum' 'search' function. Anyone know if they've now sent in the statement company law specifies? It's not unusual in the UK for a company to fail to do this on time, but it is curious if it continues.

 

[pocketkitchen]

This thread caused me to recall a recent one about MQA not having posted their company returns a while ago. However I couldn't refind that thread using the forum' 'search' function. Anyone know if they've now sent in the statement company law specifies? It's not unusual in the UK for a company to fail to do this on time, but it is curious if it continues.

They're up to date on Companies House website.

 

[Tony L]

As someone who still buys records, CDs & SACDs I’m just not in touch with streaming at all. Is MQA still a ‘thing’? If so which streaming services use it?

 

[Guest432]

As someone who still buys records, CDs & SACDs I’m just not in touch with streaming at all. Is MQA still a ‘thing’? If so which streaming services use it?

Nope it's just a stupid fad that brings no benefit to the sound (if anything it makes it worse) and is an attempt by Meridian to lock users and studios into a single licensed format.

Hopefully it will disappear into obscurity.

 

[DavidS]

Are you all living in another dimension or something.

 

[DimitryZ]

I was hoping for a healthy discussion, not a gathering of MQA hating fly swarm...

 

[booja30]

Are you all living in another dimension or something.

Is that a question.

 

[Stunsworth]

As someone who still buys records, CDs & SACDs I’m just not in touch with streaming at all. Is MQA still a ‘thing’? If so which streaming services use it?

As far as I'm aware it's still officially only Tidal, though Qobuz have a couple of albums that are identified as MQA - that's what the label submitted, and it lights up as MQA on my DAC...

https://www.qobuz.com/gb-en/album/f...qa-steve-dobrogosz-radka-toneff/czn9zsef6y7pc

https://www.qobuz.com/gb-en/album/m...anne-thorsen-trondheimsolistene/ugxl6hzkar99a

That first album by Radka Toneff is very good in an Eva Cassidy sort of way regardless of encoding.

 

[adamdea]

I have an MQA DAC - M2TECh Young III, and an non MQA modern DAC - Topping D70. On the same material available on Tidal as MQA and on Qobuz as hires, these both sound VERY similar if the low dispersion filter is enabled on rhe D70.

I would expect them to sound VERY similar if any sensible filter were used since any differences are likely to be very slight.

My understanding is the low dispersion filter is the MQA apodizing filter, which pushes all the ringing to the right in the time domain.

It will ensure that any ringing occurs after an impulse. But in doing so it will have to change the phase of the signal for all signals, not just impulses, which is the sort of thing that people very much seem to worry about in other contexts. Certainly it is in a sense changing the recorded signal.

As to whether pre-ringing matters, I am aware of no evidence that it does at anything like 20Khz even.I've tried telling minimum phase from maximum phase which is a daft filter which should be much worse than an ordinary linear phase filter.
If you are dealing with hi rez then I'm assuming the transition band of the filter is above 40Khz. At that level there really is very little information even on a good recording. In that context minimum phase filters make even less sense to me than they do for 16/44

 

[John Phillips]

I have an MQA DAC - M2TECh Young III, and an non MQA modern DAC - Topping D70. On the same material available on Tidal as MQA and on Qobuz as hires, these both sound VERY similar if the low dispersion filter is enabled on rhe D70. My understanding is the low dispersion filter is the MQA apodizing filter, which pushes all the ringing to the right in the time domain.

Comments? Opinions?

I think the "low dispersion" AKM filter in the D70 has both pre-ringing and post-ringing in its impulse response (but mostly post-ringing). See here about 2/3-way down the page.

It does not seem to exactly resemble the impulse response any of the MQA filters as shown here. But as the latter are of proprietary specification, I think, nothing can be said for certain.

 

[John Phillips]

I would expect them to sound VERY similar if any sensible filter were used since any differences are likely to be very slight.
…
As to whether pre-ringing matters, I am aware of no evidence that it does at anything like 20Khz even.I've tried telling minimum phase from maximum phase which is a daft filter which should be much worse than an ordinary linear phase filter. …

I have done the same sort of test with SoX's filter when up-sampling to 384 ksamples/s into my AK4490-based DAC. The results were, to me anyway, so similar that I concluded that manufacturers probably offer filter choice more because audiophiles demand that there be a tweak to try out, than for any significant audible difference.

 

[Julf]

I concluded that manufacturers probably offer filter choice more because audiophiles demand that there be a tweak to try out, than for any significant audible difference.

That is my theory as well.

 

[darrenyeats]

I prefer intermediate phase filter (SoX) over linear phase filter for long term listening. Sometimes with linear phase I get a sense that the sound is cold. Not all the time but now and then.

This has never, ever happened to me with intermediate phase.

On a quick A/B I hear no difference, so if this is a real thing it's subtle.

All comments in my own system. And I don't say a minimum-ish phase filter alone is sufficient for good sound, other things must be right too.

PS: See https://pinkfishmedia.net/forum/threads/digital-filtering.221996/ for pictures, minimum vs intermediate phase in SoX.

 

[DimitryZ]

I think the "low dispersion" AKM filter in the D70 has both pre-ringing and post-ringing in its impulse response (but mostly post-ringing). See here about 2/3-way down the page.

It does not seem to exactly resemble the impulse response any of the MQA filters as shown here. But as the latter are of proprietary specification, I think, nothing can be said for certain.

Thank you for linking this. There is a detailed tech datasheet for the AK4497, which describes all the filters.


https://drive.google.com/file/d/1AiZaJPWimCxEy9YExJaIbrjO5LzWpxPq/view?usp=drivesdk


ASR measurements of the D70, suggest that the low dispersion filter has a pretty sharp frequency cutoff, in contrast with the slow and super slow ones.

 

[Jim Audiomisc]

It will ensure that any ringing occurs after an impulse. But in doing so it will have to change the phase of the signal for all signals, not just impulses, which is the sort of thing that people very much seem to worry about in other contexts. Certainly it is in a sense changing the recorded signal.

The key point of having a standard 'time symmetric' sinc reconstruction filter is that it outputs the analogue waveform *defined by the recording process* which includes the choice of ADC. Thus it is the 'correct' result. i.e. if the creators of the digital recording wanted to have no pre-ringing they could have produced a recording that provides this with a standard 'sinc' DAC reconstruction filter.

So in reality, if you have a 'slow' reconstruction filter it may time smear a recording that was originally made with an ADC input chain that avoided pre-ringing. So if you think you dislike time 'smear' it may make the results worse in such cases. It isn't a magic bullet.

My personal guess is that when people prefer one reconstruction to another they may well simply be using the choice as an HF 'tone control' to tweak the HF levels they hear. Possibly offsetting a departure elsewhere in the record -> replay chain.

But again, personally, I've never felt the difference were worth bothering about in the systems I've used. YMMV