Rega DAC filter settings

Discussion in 'Audio Hardware' started by TVC15, Jan 17, 2011.

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  1. TVC15

    TVC15 Forum Resident Thread Starter

    Location:
    New Jersey
    Hello all... curious what the filter settings for the new Rega DAC actually do, and how these might impact sound quality. Honestly, I'm not really hearing much of a difference, if any, so I wonder of the usefulness of this feature. But if I know what to listen for... perhaps I can improve my ear in the process.

    Here are the different settings:

    (low sample rates 32/44.1/48K)
    1 Linear phase half-band filter
    2 Minimum phase soft-knee filter
    3 Minimum phase half-band filter
    4 Linear phase apodising filter
    5 Minimum phase apodising filter


    (medium & high sample rates 88.2/96 & 176.4/192K)
    1 Linear phase soft-knee filter
    2 Minimum phase soft-knee filter
    3 Linear phase brickwall filter
    4 Minimum phase apodising filter
    5 Linear phase apodising filter

    Thanks!
     
  2. Minimum phase apodising filter is the rage du jour.

    "Soft-knee" filter means "slow rolloff," another filter algorithm that saw its heyday a few years ago. Esoteric calls this filter topology "RDOT."

    Linear phase brickwall filter sounds like a standard sharp roll off FIR (finite impulse response or non-recursive) filter.
     
  3. See here too:

    http://www.stereophile.com/features/106ringing/index.html

    Also, check out the white papers on Ayre's website for their "MP" filter (slow roll-off minimum phase filter [non-apodising]) and on Meridian's website for their slow roll-off, minimum phase apodising filter.
     
  4. TVC15

    TVC15 Forum Resident Thread Starter

    Location:
    New Jersey
    Thanks for all of those links, will do some research.

    Now honestly, I can't hear much above 17khz. Is any of this going to really matter for me? Or is there some affect in the lower frequencies as well?
     
  5. TONEPUB

    TONEPUB Senior Member

    Location:
    Portland, Oregon
    Just listen and see which one you prefer....
     
  6. TVC15

    TVC15 Forum Resident Thread Starter

    Location:
    New Jersey
    Well I've tried that but not hearing a whole lot of difference. Perhaps beyond my range of hearing, or perhaps this represents an ear training opportunity. Was curious if anyone might be able to describe what these different settings do, sonically.
     
  7. KT88

    KT88 Senior Member

    So far, that's the setting that I have preferred for many CD's. It sounds smooth and yet immediate. Some others were hardly noticeable in their differences or were not as sweet and it depends upon several things. One thing is the source as not every CD has the same level of detail or sonic attributes that allow the subtle differences to be revealed. Of course your hearing ability can have some bearing as well. Much of the effect is in the highest frequency ranges. Also the loudspeakers response matters. The more transparent the rest of the system, the more the effects can be heard.
    -Bill
     
  8. TVC15

    TVC15 Forum Resident Thread Starter

    Location:
    New Jersey
    I have Thiel 2 2's, so those should be pretty revealing. But if I can't hear above 17khz then it may all be lost on me....
     
  9. KT88

    KT88 Senior Member

    I'd not give up hope just yet. There are audible parts further down in the spectrum. It'll just take the right tracks and moon phase to hear them. It's really a subtle effect, so when you do hear the change, it'll not clobber you over the head. On some tracks, I have trouble hearing a difference between a few similar DACs, so narrowing it down to one DAC and a slight change to the HF response, it becomes even more challenging. The system really does need to be quite revealing.

    I don't even have the one on display here in the best system, so it will become even more revealing once I shuffle the equipment. It's not shabby though. I am comparing the Rega DAC directly to the Cambridge Audio DacMagic and the Music Hall 25.3 DAC.

    The rest of the system has identical digital and analog audio cables, Cambridge Audio 840E preamplifier, Cambridge Audio 840W power amplifier, and Dali Ikon 6 Mk2 loudspeakers.
    -Bill
     
  10. TVC15

    TVC15 Forum Resident Thread Starter

    Location:
    New Jersey
    Oh, I love the Rega DAC. It's just the various filter settings aren't making a difference for me. Perhaps I'm switching back and forth to quickly, waiting to hear something obvious, when I should just pick a setting, live a week with it, then try another, etc.
     
  11. KT88

    KT88 Senior Member

    I know; I was suggesting that you should not lose hope that you can hear the difference in the filters. It isn't suppose to be obvious. If it were, something would be wrong. I mean, a high fidelity system should not change the input, it should reproduce it faithfully. So any filter that was heavy enough to have a pronounced influence on the sound would be an EQ or tone circuit, not an out of band filter.
    -Bill
     
  12. Averara

    Averara New Member

    Location:
    Lisboa, Portugal
    jlw2000, do you notice any difference in terms of listening fatigue after a few hours listening with each filter setting?
     
  13. TVC15

    TVC15 Forum Resident Thread Starter

    Location:
    New Jersey
    I don't get fatigued listening to music after a few hours, typically. My sessions go for 3-4 hours, usually 9pm - 1am. Sometimes actively listening, sometimes background while doing something else. I watch very little TV.

    Right now I'm on filter setting #4 and will keep it there for awhile. Then one day I'll swap and see if I hear anything.
     
  14. Spitfire

    Spitfire Senior Member

    Location:
    Pacific Northwest
    What DAC chip does the Rega have?
     
  15. KT88

    KT88 Senior Member

    A pair of Wolfson WM8742 DAC's in parallel.
    -Bill
     
  16. Spitfire

    Spitfire Senior Member

    Location:
    Pacific Northwest
    Thanks. This DAC can do DSD. Too bad Rega doesn't make a nice SACD player with them. Here's some info: http://www.wolfsonmicro.com/products/dacs/WM8742/

    The datasheet link has some info about the filters.
     
  17. JonP

    JonP Active Member


    Try listening to some classical orchestral music and the differences between the filters should be a lot more obvious. For example, you should be able to observe the first violins sounding a bit more metallic and edgy with the minimum phase filter types but conversely the notes upon change of bow will also seem to start more decisively with a clearer "bite" to them and you will thus get a slightly better sense of the individual players making up the section (since the players being human, there is no such thing as all the players playing in perfect synchronisation, plus each violin / bow / string brand and type / player combination will sound different).

    On the other hand, the linear filters, especially the soft knee should make the violins and woodwind sound a bit warmer and silkier, but also a bit more clouded in sound, with the starts of notes upon bow changes (in the case of the strings) being less clear and well-defined compared to the minimum phase filters. The linear filters may also make the individual contributions of each player less obvious.

    In my opinion, the best combination of filtering would be the soft knee linear filter when used in conjunction with high resolution, high sample rate source material, whereas the minimum phase filters may in some circumstances provide a subjectively better sound with low resolution source material.
     
    jonasbegood likes this.
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