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  1. #1
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    digital output format?

    I am sending the output of the squeezebox to a behringer digital equalizer to a benchmark dac. I'd like to make sure I am getting the best possible quality. Is the digital output of the squeezebox always 24 bit resolution, or does it depend on the source file?

    I think the behringer uses the input format as the output format, so it would make sense that starting with 24 bits would be better before equalization. Also the equalizer has a dithering setting, should this be on or off with the squeezebox output?

  2. #2
    Senior Member pfarrell's Avatar
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    digital output format?

    On Tue, 2005-08-30 at 12:58 -0700, mazurek wrote:
    > I am sending the output of the squeezebox to a behringer digital
    > equalizer to a benchmark dac. I'd like to make sure I am getting the
    > best possible quality.


    The audiophile answer would be to not use the equalizer. The fewer
    things in the chain to mess it up, the better.

    A lot of audiophile preamps and integrated amps don't even have
    bass and treble knobs for the same reason, fewer things to mess
    up the music.

    > Also the equalizer has a dithering setting, should this
    > be on or off with the squeezebox output?


    Dither is critical every time you reduce the number of bits in
    a signal. If you are feeding the Benchmark and it is doing 24 bit
    processing, there is no reduction in the number of bits.

    But you may be doing something. If you multiply two 24 bit numbers
    together, you get a 48 bit answer. Or more properly,
    up to a 48 bit answer depending on what you are multiplying.
    If you then map that answer back to 24 bits, you need dithering.

    BTW, the Behringer brand is not normally considered in the same
    class as the Benchmark DAC-1. They have good products at very good
    prices, but audiophiles sometimes scoff at the brand.


    --
    Pat
    http://www.pfarrell.com/music/slimse...msoftware.html



  3. #3
    Senior Member Mike Hanson's Avatar
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    Quote Originally Posted by mazurek
    Is the digital output of the squeezebox always 24 bit resolution, or does it depend on the source file?
    Ripped WAVs from CDs are 16-bit, so 24-bit will not happen.

    I'll second Pat's comments: equalizers are generally frowned upon in the audiophile world. I would skip it, unless you have an unbearable desire to twiddle knobs.

    -=> Mike Hanson <=-

  4. #4
    Gadfly, Former Founder Slim Devices dean's Avatar
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    Re: digital output format?

    On Aug 30, 2005, at 1:22 PM, Mike Hanson wrote:

    >
    > mazurek Wrote:
    >
    >> Is the digital output of the squeezebox always 24 bit resolution, or
    >> does it depend on the source file?
    >>

    > Ripped WAVs from CDs are 16-bit, so 24-bit will not happen.

    Yes, but... MP3 is a lossy encoding. Our MP3 decoder does generate
    24 bits of output.

    Then decoded MP3 and FLAC audio may have a volume adjustment applied
    to it with 24 bits of accuracy.

    The D/A converter then gets 24 bit output. S/PDIF output will be
    converted back to 16 bits.

  5. #5
    Founder, Slim Devices seanadams's Avatar
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    Quote Originally Posted by dean
    S/PDIF output will be
    converted back to 16 bits.
    Correction: we output 24-bits to both the s/pdif and the internal DAC.

  6. #6
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    Behringer Digital EQ

    For what it's worth, I use the Behringer EQ completely in digital mode, and I've found it to be not only totally transparant but to have a very decent DAC to boot. I use the SB's digital out to the DEQX 2496 and I find it an absolute dream - and find that MP3's on shoutcast radio stations (128k or higher) sound surprisingly good.

    The audiophile answer to not use an EQ applied more when EQ's were in the analog domain with all their attendant filters and electronics - when in purely digital mode all it does is alter the bitstream, I can find no lack of transparancy via my Quad electrostatics at all and that says a lot. When I switch back to non-eq mode now and hear the bass bouncing all over the room, I quickly realize that whatever slight loss in transparacy there may be, it pales in comparison to the room problems it solves!

    I'm still absolutely amazed that MP3 streams at 128k are as listenable as they are via the SB. Many 128k stations are not that good - perhaps they play comprimised MP3 sources or don't have as good an encoding scheme as other stations, but those stations that play CD's at the source with good encoding to 128k sound surprisingly good. I'm getting a faster modem to tap into the 320k bitstreams, very interested to hear how they sound.

    You'll love the Behringer + SB - and if you want a different sound, you can add a DAC onto the end of the Behringer - perhaps a tube based DAC. True, you're adding some jitter possibilities, but I've found the jitter from the SB to the Behringer negligable - it sounds fantastic!

  7. #7
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    Dither setting

    Whoops! Forgot to answer your actual question - I assume the "Dither" setting you refer to is on "Page 2" of the "I/O" menu? Mine is set to 24 bit and sounds great, although I haven't tried turning it off. I think 24 bit is the factory default. However I don't know if it even matters if the Behringer is not feeding an external DAC.

    I'd sure love to hear the Benchmark on the end of my Behringer - now there's an empirical mod for the Benchmark too, but man is it expensive. Never seems to end.

  8. #8
    Senior Member pfarrell's Avatar
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    Re: digital output format?

    On Tue, 2005-08-30 at 20:36 -0700, quadguy wrote:
    > The audiophile answer to not use an EQ applied more when EQ's were in
    > the analog domain with all their attendant filters and electronics -
    > when in purely digital mode all it does is alter the bitstream,


    if you like it, use it. Use your ears, not mine.

    But applying EQ without impacting phase is very hard.
    It takes very fancy algorithms and lots of computation.
    Impacting some frequency's phase and not others can
    have serious impact.

    Many of the EQs used in professional studios and mastering
    houses are not phase neutral. Some have specific "color" that
    can be used as an effect. Often times, it is a good effect.
    Often the specific color of the EQ means people pay serious
    money to get the exact Class-A discrete circuit, API, Neve
    and other companies made or make EQs that cost thousands of
    dollars per channel.

    As I've posted before, humans are much more sensitive to
    phase than they are to frequency response.

    The bitstream is the music. Altering the bitstream
    changes the music.


    --
    Pat
    http://www.pfarrell.com/music/slimse...msoftware.html



  9. #9
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    Agreed

    Agreed, it doesn't attempt to handle phase relationships as would an expensive Tact unit for example. But I only EQ bass and the effects on phase from say 250Hz down are far less evident than if one were EQ-ing the critical midrange region. I bought it to take the boom out of the room, and it does that with no apparant negatives, far better than my expensive ASC tube traps ever did. With my Quads + Behringer, I can hear soundstage info pasted to the left/right walls of my 23' wide room and a smooth spread of sound from stage right to left - so if phase is reflected in imaging, there's no problem when not EQ-ing above the bass. Abient recordings image waaaay outside the speaker boundaries, even on some MP3 stations, and dance and techno are a pure acid trip. This all happens with the Behringer's internal DAC which was just a pleasant surprise and bonus for me - I wasn't even sure it had a DAC when I bought it, I thought it was a purely digital device considering it's cheap price.

    There are a few professional reviews out there that compare it's digital to it's analog mode, and although they generally say it's fine in analog mode, but the digital mode is far superior - of course in analog mode, you have to undergo an additional A/D conversion to get the advantage of the Digital EQ, so it's no wonder things are getting rough when you go that way.

    When I run the digital signal through the Digital EQ with no EQ settings - all flat - there's no difference at all. When the EQ settings are changed to equalize the bass the difference in quality of sound overall is so massive once the room-boom is gone, trying to split hairs over minute changes in transparancy is near impossible, and pointless really compared to the overall improvement. Them's my ears anwyay, in my room.

    The reason I mention this is that after having suffered with room problems for the past 15 years of my audiophile career, I've never found anything so remarkable in it's level of improvement for so little money - $300 US street price - I'd hate to see others pass up such a bargain if the have roomboom problems. My ASC tube traps were thousands and thousands of dollars, and so terribly ugly - they're long gone now, got back fifty cents on the dollar for them, for a net loss of many thousands.

  10. #10
    Senior Member pfarrell's Avatar
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    Re: digital output format?

    On Tue, 2005-08-30 at 22:00 -0700, quadguy wrote:
    > With my Quads


    I'm in serious lust mode for some Quads. They have sounded great
    every time I listen to them. But they are too big, require too big
    a room, and totally flunk the WAF in my world.


    > There are a few professional reviews out there that compare it's
    > digital to it's analog mode,


    Got any URLs? I find "professional audio" trade magazines to have
    even less credibility than the high-end audiophile stuff. Most of them
    do not really review stuff. One of my big shocks getting into recording
    was that I've been reading the car buff books for 25+ years. They
    regularly do comparisons with four or more cars aimed at the same
    market. The "Recording" and "Mix" and the like never compare and
    rarely make more that "you should consider this" as a comment.

    > The reason I mention this is that after having suffered with room
    > problems for the past 15 years of my audiophile career,


    Room problems are serious and I think under considered.
    Guess it is easier to buy a $400 interconnect than fix a
    listening room that is 8x8x24.

    Real Traps, sold by Ethan Winer, actually are big enough, and
    are really engineered to stop the 80 to 300 hz standing waves that
    typical home listening rooms are cursed with. They are not cheap,
    and don't pass WAF for me. Acoustic treatment is tough. The random
    "skyline" diffusers work, but at frequencies that are usually not the
    major problem. To work at room standing wave frequencies, each "step"
    has to be about four inches, and you need to cover many feet.
    Cue Recording Studio has a suitable low frequency diffuser in
    their "A studio" that you can see in the background of
    http://www.cuerecording.com/aroom.htm


    There is no way such a treatment will exist anywhere near
    my living space. In my studio, I use lots of old sofa, etc.

    --
    Pat Farrell PRC recording studio
    http://www.pfarrell.com/PRC



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