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Why would I want selectable Digital Filters in a DAC?

137.254.4.11

Posted on August 31, 2015 at 15:05:57
jedrider
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I saw it crop up twice in two days now: A Music Fidelity DAC and a Grace DAC. So, why would I need one?

If you tell me I'll go crazy trying to decide which I prefer, then I'm definitely crossing these DACs off my list!

 

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RE: Why would I want selectable Digital Filters in a DAC?, posted on August 31, 2015 at 15:26:39
Kal Rubinson
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That is a great question. It is my experience that, indeed, switching among filters can change the sound but I find that yet another confusing distraction that leads to compulsive behavior. I'd rather a DAC maker commit to what he/she thinks is best and, ideally, be able to update it as needed.

There's already too many trivial distractions in this hobby.

 

RE: "yet another confusing distraction that leads to compulsive behavior"..., posted on August 31, 2015 at 15:51:32
Ivan303
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Indeed it does.

One should not be flipping switches on their DACs, trying to find different and perhaps better sound.

They should be swapping out their DACs, keeping the wheels cf the audio equipment industry rolling! :-)





 

RE: Why would I want selectable Digital Filters in a DAC?, posted on August 31, 2015 at 16:13:44
PAR
It depends partly on your psychology. If you are someone who fidgets around a lot with equipment, maybe tending to swap gear regularly and at short intervals, then selectable digital filters may not be a good option for you as you may spend more time playing around with them than listening to music.

However if you are able simply to spend a couple of days initially working out your favourite filter then it should be a case of set and forget.

Your taste and supporting equipment may not be identical to the manufactuer's so their choice or recommendation may not suit you or your set up. Further if you subsequently change equipment then you may find that your new stuff sounds better with a different filter than you had been using to date. At least with selectable filters you don't necessarily find that you now also need to replace your otherwise perectly good DAC because you are stuck with no choice.

In addition certain DACs which offer selectable filters are also capable of having them field upgraded as design progresses.

Properly done and used with discipline, selectable filters can offer a lot. I have been running DACs having 6 selectable filters for PCM and 2 for SACD for over 15 years. Although I rarely change my selection the opportunity to do so has proved of great value over time as other factors in my system have changed.

 

RE: "yet another confusing distraction that leads to compulsive behavior"..., posted on August 31, 2015 at 17:04:35
Kal Rubinson
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You are welcome to do all that flipping and trying if you choose. I find it numbing.

The inference about my motives is unfounded as this is a purely personal preference. If you knew me better, you would see that I not fickle in my choices.

 

RE: Why would I want selectable Digital Filters in a DAC?, posted on August 31, 2015 at 18:11:31
Doug A
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My two cents, and in no way humble opinion: I have a Rega DAC with selectable filters, and I ended up looking for the best filter for a given type of music. Yes, I went nuts. I did eventually find an all-purpose filter, and I stuck with that for quite a while.

But now I'm using the internal DAC in a Squeezebox Touch. I will have an external DAC again someday; but it won't have selectable filters.
"Do you need those light bulbs on your stereo?" - my niece, looking at a Dynaco ST-70

 

Because Minimum Phase Filters are Inherently Superior, but some folks insist on driving Edsels, posted on August 31, 2015 at 19:23:16
John Marks
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Howdja like them apples?

jm

 

RE: 'fickle', posted on August 31, 2015 at 19:50:36
Ivan303
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Most of my audio gear is over a decade old, that's with the exception of computer/streaming stuff which is a relatively new to me.

Plus I have never subscribed to an audio journal and would have never had a copy of one in my hands except for the fact that they give them away free at audio shows.

I currently have BOTH Stereophile AND Absolute Sound around here someplace, thanks to the California Audio Show a week or two ago.

Do you have a piece in one of them?



 

Because......, posted on August 31, 2015 at 22:38:25
Todd Krieger
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The sample rate of 44.1 kHz for CD playback is the main reason why we've had digital filtering, because there is such a small gap between the generally-accepted top of the audible range (20 kHz) and half the CD's sample rate (22.05 kHz), the highest reproducible frequency per Nyquist's Sampling Theorem. CD is ideally reproduced with full passband at 20 kHz with full stopband at 22.05 kHz. Since ringing would be introduced with "perfect" filtering with the passband and stopband so close together, time "smearing" exists at the top of the audible band.

So the sample rate of 44.1 kHz for CD playback leads to a compromise, top-end frequency response versus time response. The DAC's filtering can be optimized for either flat frequency response or time response. Or somewhere in between.

Long filters generally do best with flat measured frequency response to 20 kHz, but have "smeared" (ringing) time response. (These filters closest resemble the ideal filter per Shannon/Nyquist.) Short filters have a slightly rolled off top end at 20 kHz, and better time (transient) response than long filters. Non-oversampling filter-less designs (NOS) do best with transients and time response, but have the most "rolled off" top, due to nulls/modulation in the sampling toward the top of the audible band.

There is also a choice between "linear phase" and "minimum phase" filters. Linear phase has zero average phase error through the frequency range, but minimum phase filters better resolve the attacks and decays in music. (NOS designs do not have this option.)

If the music is heavy in HF information or transients, a short minimum phase filter might be ideal. If the music is more continuous, like Samuel Barber's "Adagio for Strings", a long linear phase filter might be ideal. If the music is small scale like a folk ballad or string quartet, a NOS design might be ideal. Your mileage may vary.

No single filter is ideal for all music. I generally prefer short minimum phase filters personally, if I were to choose just one filter type. But other listeners might prefer other filter types.

And finally, if you're loaned a DAC with these filter options, you can find out which filter types are most suited for your music and listening. You can then acquire a DAC with the filter type you most prefer.

 

RE: 'fickle', posted on September 1, 2015 at 06:47:36
Kal Rubinson
Reviewer

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I don't know what issue you have, so I cannot say. As a reviewer, it is necessary for me to have reference equipment and that means that it needs to be of recent manufacture to be relevant to the reader. Also, I need keep up with new technology.

That said, I just changed the speakers in my CT house for the first time in about a decade and the main power amp there was purchased in 2000. One of the amps I use every day in the NYC system was purchased in 1995. OTOH, I change among EQs, DACs and file-streaming stuff more frequently because the technology is changing rapidly. I don't change cables unless absolutely necessary.

 

RE: Why would I want selectable Digital Filters in a DAC?, posted on September 1, 2015 at 08:22:28
Thorsten
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Hi,

The main reason would be that some Digital Filters measure very well when using something like an AP2, but the sound quality is not great.

On the other hand some of the Filters that many find good sounding (including no filter at all) measure, shall we say interesting, on an AP2 (here is one for the AP2 and 'scope jockeyes - how come often what measures quite poor sounds great?).

One way around this is to make the filter switchable, Ayre did this quite tongue firmly in cheek by labelling one position for the filter "Listen" and the other "measure". So AP2 and 'scope jockys can marvel about the great measured results while people who prefer to listen to music may choose what sounds better and not worry about what it measures like.

Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?

 

So, PERFECT sound is not even possible!, posted on September 1, 2015 at 09:15:41
jedrider
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I thought so.

 

Because recordings are made with different filters, posted on September 1, 2015 at 09:21:49
Tony Lauck
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When playing a CD there are two filters that are relevant. The filter used to make the recording and the filter used to playback the recording. These two filters interact and their interaction is well predicted both by theory and practice. One can look at waveform plots and see this interaction on test signals and one can listen to music and hear this interaction. The situation is like a subtle form of the LP equalization debate prior to the adoption of the RIAA curve. If the audiophile used the wrong equalization he would not hear what the mastering engineer intended.


Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

Not at 44.1 kHz. nt, posted on September 1, 2015 at 09:25:05
Tony Lauck
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Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

However, CD can be much better than most vinylphiles think, posted on September 1, 2015 at 09:54:30
John Marks
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You need a nice (literally) clean CD, played on a Read Until Right transport with vanishingly low jitter, such as Parasound's CD-1, a S/PDIF cable that does not mess things up, and a superb DAC with sophisticated filters, such as Bricasti's M1.

Under such conditions, CDs can be astonishingly good, especially CDs that were themselves remasterings of golden-era master tapes.

Yes, an unedited raw pure DSD file will sound better--but in almost every case, there will be a better performance of that particular piece of music.

jm

 

Now, you have REALLY messed up my mind, posted on September 1, 2015 at 10:27:17
jedrider
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I don't think I will recover from that.

 

RE: Because recordings are made with different filters, posted on September 1, 2015 at 10:32:47
I would bet must people never hear what was intended

 

RE: Because recordings are made with different filters, posted on September 1, 2015 at 10:57:35
Tony Lauck
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"I would bet must people never hear what was intended"

I have, because I listen to my own recordings and I can compare the hi-res studio master with the 44/16 version to see how far they deviate. :-)

I have said before, and I guess I have to say it again, if one only plays back recordings and does not make them, then one is not fully participating in the audio hobby. No problem if one is a music lover, but if one thinks of himself as an audiophile he should understand the technology and this is simply not possible without some experience of the entire record - playback process. (In the case of DACs, this at least means use of ADCs as well as DACs.)

Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

What is perfect sound?, posted on September 1, 2015 at 12:33:19
sbrians
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Even live, maybe I don't like the type of strings that a player is using, etc. Then even this perfect "playback" is "flawed".

I eventually found that my goal is not perfect sound, but maximized enjoyment of music.

 

Doesn't matter, as long as it's "Forever" , posted on September 1, 2015 at 13:04:35
The "forever" part made those yuppies reach for their wallets. A good investment is nothing to sneeze at.

 

But whatever sound it is...., posted on September 1, 2015 at 14:35:17
Ivan303
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it's forever.



 

RE: Because recordings are made with different filters, posted on September 1, 2015 at 16:37:06
Like I said Most People


 

RE: Not at 44.1 kHz. nt, posted on September 1, 2015 at 17:09:52
ahendler
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I think redbook can be superb with good equipment. My vinyl sounds great and my cd's as well as streaming are wonderful. I enjoy my system no matter what medium I play back in and yes I have heard Hi-Rez downloads all the way up to DSD and don't find any more enjoyment from them.
Alan

 

Agreed. And for me, the only credible reason. nt, posted on September 1, 2015 at 18:24:39
jusbe
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Big J

"... only a very few individuals understand as yet that personal salvation is a contradiction in terms."


 

Disagree., posted on September 1, 2015 at 18:27:08
jusbe
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Reebok can sound great. DSD and other formats can sound different, but better?

Setting aside the truly hi-res workflow, from recording to publishing (which still seems rare), are we really getting any more music or even verisimilitude from hi-res manipulation in the mastering chain if it's not captured at source?

Otherwise we may as well argue that we'll never, ever have perfect anything - or simply down tools as a species and camp right here, where we are now.


Big J

"... only a very few individuals understand as yet that personal salvation is a contradiction in terms."


 

Not possible, forever? (nt), posted on September 2, 2015 at 07:53:31
Crazy Dave
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I stay away from ANY machine which has selectable filters, posted on September 2, 2015 at 08:46:52
jbcortes
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It's funny because I was pondering that very same question yesterday. It's like these days, you can't buy a machine without selectable filters. It's the latest fad. "Decide for yourself".

So I'lI say it: I want designers who have balls and make a statement through their product. I don't want to have a choice other than which DAC I'll end up buying.

Maybe different filters sound better with different CDs, but life is definitely too short for me to determine which filter sounds best with any of my hundreds of CDs.

I have a DAC I adore now, it doesn't allow for filter selection, and yet it's the best sound I've ever heard from digital, and I was a 100% analogue guy at some point.

Filters are for companies who are not sure what to aim for and have no vision, or don't want to have one. Controversial position but hey, people don't have to share it :)

 

"I have a DAC I adore now", posted on September 2, 2015 at 09:03:36
oldmkvi
Audiophile

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And the Winner Is....

 

I remember back-in-the-day when Wadia was initially skewered..., posted on September 2, 2015 at 09:11:26
meisterkleef
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for not having a perfectly flat FR with their slow-rolloff linear phase Digimaster filter.

While slow-rolloff LP/MP filters are commonplace now, Wadia was significantly ahead of their time trying to market such a thing in the "perfect sound forever" 80s.

 

RE: "I have a DAC I adore now", posted on September 2, 2015 at 10:11:03
jbcortes
Audiophile

Posts: 1378
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It's in my profile :)

Brinkmann Zenith (based on Philips TDA1541).

 

OK, Thanks. nt, posted on September 2, 2015 at 10:19:33
oldmkvi
Audiophile

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/

 

We only have 'Smoke'N Grills' here that are Brinkmann's NT, posted on September 2, 2015 at 10:49:09
jedrider
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Joined: December 26, 2003

 

Agreed...... But........., posted on September 2, 2015 at 11:25:24
Todd Krieger
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SO few DACs and CD players truly bring the medium to its potential.

Prior to the experience I had with the Wadia 7/9 transport and DAC, I once thought CD was hopelessly inadequate for true high-fidelity playback..... Since that experience, my everlasting quest to replicate that Wadia experience.

It wasn't until I attained the Prism DA-2 DAC, and later the Don Allen/Philips CDC-935 CD changer, where I thought I could live with only CDs as my playback source. Yet even there, I still give vinyl a slight edge overall.

In regard to the time response/frequency response compromise with CD playback, I think the key is attaining a happy medium where neither flaw can be readily noticed. I once thought this couldn't be done, but I think I'm close.

 

RE: So, PERFECT sound is not even possible!, posted on September 2, 2015 at 11:34:30
Todd Krieger
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I think when 44.1 kHz was selected for the sample rate (I still don't know how they decided on such an oddball frequency), there was too much faith in the Nyquist/Shannon Sampling Theorem, which unfortunately only holds true for steady state signals. But music isn't steady state. The theorem falls down with non-steady state "transient" events, where "ringing" is introduced in the time domain (using the so-called "perfect" sinc filter). So the "perfect" sound couldn't truly be perfect.

I've had debates with theoretical engineers who thought I was a crackpot for questioning this theorem for audio application..... They treated the time domain issues as a strawman argument.

 

RE: Because recordings are made with different filters, posted on September 2, 2015 at 12:13:19
Todd Krieger
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Since the A/D filtering method is almost never disclosed with a recording, we have to fall back on the music type, in regard to selection of the best-suited D/A filtering method.

If the A/D filtering method were disclosed with all recordings, I agree it would take a lot of guesswork and evaluation out of the D/A filter selection process.

 

RE: Because recordings are made with different filters, posted on September 2, 2015 at 12:49:07
Tony Lauck
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Neither the A/D filter mode or the polarity (absolute phase) are disclosed. However, to the extent that they matter they are readily discernible by listening. I suspect, but I haven't tried confirming this, that one can discern the general parameters from examining the files, e.g. looking at spectrograms and waveform plots of transients.

The most important parameters of a filter are 1. its center frequency, 2. the width of the transition zone, 3. the depth of the transition zone, and 4. whether the filter is linear phase, minimum phase, or some mixture thereof. The first three factors are readily pulled from spectral plots. If one can find a transient in the music at the right point, one can see the extent of "pre-ringing". This will not necessarily answer which filters are best for playback, because there are other issues as well, e.g. tonal balance issues a function of microphone placement and EQ and system "house curve" issues as a result of speaker/room interactions.



Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

RE: "I have a DAC I adore now", posted on September 2, 2015 at 16:54:55
Todd Krieger
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Should have just said "Zenith"..... Would have thrown everyone here for a loop...........

 

RE: Why would I want selectable Digital Filters in a DAC?, posted on September 2, 2015 at 21:21:10
AbeCollins
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Contributor
  Since:
February 2, 2002
I had a $5000 DAC with selectable digital filters. Set it once and left it there until I sold the DAC. None of the filter settings made it sound better than the two DACs that I presently own.

Both of my DACs have very different fixed filter designs.

My favorite has a "minimum phase digital filter" using custom DSP implemented in FPGAs.

My other DAC (an outstanding bargain buy IMHO) has an all passive analog filter.


 

Go down to Tony Lauck's reply and ignore, posted on September 3, 2015 at 05:04:50
fmak
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those who just post what they did, with or without pictures.

The roll off point, the slope, and the type of digital filter all affect ultimate sound quality. One issue is how these are implemented and with what algorithm. Often it is a suck it and see thing.

 

RE: Not at 44.1 kHz. nt +10, posted on September 3, 2015 at 05:07:25
fmak
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nt

 

"I want designers who have balls and make a statement through their product. I don't want to have a choice ", posted on September 3, 2015 at 05:08:47
Awe-d-o-file
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I hear you but I would say that often in electronics decisions are made where the choice comes down to making one area better at the expense of another. A compromise in other words. Like the topic of negative feedback in an amplifier for instance.

So maybe the manufacturer has a preferred setting but still chooses to add the multiple choices because he thinks that some may like a different choice than his. Even if that decision is made just to make the product look more flexible which it would be.


I don't have a DAC with adjustments and if I heard a DAC that had adjustments and did prefer one over all the others I don't think all DAC's would need that switch. I think it should be decided case by case. I've read several reviews of DAC's with those adjustable filters where the reviewers did hear differences and referred one setting over another.


E
T




ET

"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936

 

+1, posted on September 3, 2015 at 05:10:35
Awe-d-o-file
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yep, that's how I see it. As George W. Bush once said "I'm the decider". Hey, that's a good one!~


E
T

ET

"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936

 

Blind squirrel finds nut... , posted on September 3, 2015 at 07:21:46
Ivan303
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Not often, mind you, but this time you did!

With and assist from Tony.





 

RE: "A compromise"...., posted on September 3, 2015 at 07:28:00
Ivan303
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Which, in this case, is the recording process that, at some point, takes a perfectly good analog audio signal and turns it into digital.

Then leaves the job of returning it back to analog up to us in our home systems.

Not an easy job. More bit depth and/or higher sampling rates do not necessarily make it easier or better. In fact one could argue the opposite.









 

Yes but can he "bust" said nut? n/t, posted on September 4, 2015 at 07:35:51
Awe-d-o-file
Dealer

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ET

"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936

 

RE: "A compromise"...., posted on September 4, 2015 at 07:39:48
Awe-d-o-file
Dealer

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except I usually feel only 1 in 20 recordings at most are perfectly good anyway. Most are very lackluster in many ways. That just makes the gems all that much better.


E
T

ET

"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936

 

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