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  1. #1
    Senior Member
    Join Date
    Oct 2010
    Posts
    150

    Touch EDO versus Allo Sparky Usbridge - actually compared. Why is Touch compressed?

    Hi there everybody!


    Long story short: Why does the "Touch" with Enhanced Digital Output over USB sound compressed and narrow compared side-by-side to the USBridge? Both playing obviously at 100% volume on the Squeezebox Server and Client - Side. Is there a setting I have overseen...?


    The long version:

    I used the Touch with EDO for many years, with a (rather) nice hifi-chain behind it.

    And I was believing that this was "as good as it gets".

    Then I was away from home for some months and had no access to my beloved Touch and hifi-system. So, I searched a temporary solution: Not too bad sounding but not too expensive. I got myself a "USBridge" from Allo based on "Sparky" (and attached it to a nice hifi-setup, however many levels cheaper than the previous one). I have no idea of this Sparky-kind of gear, however, I guess this is some kind of experimental minimalist computer, much like what's more well known as "Raspberry Pi", combined with an additional board festering just one USB - Port that is supposed to be uncoupled from "noisy" electronics, re-clocked and "clean". Whatever that means. And it has Squeezelite on it and therefore works as a squeezebox client. It was a true pain i. t. a. to get it configured tough... hours of trial and error, rebooting etc. until I found the right parameters to get my (temporary) DAC to work communicate right with the USBridge over asynchronous USB audio 2.0. And instructions that are understandable for a non-linux-coder as me are obviously nothing that "Allo" would care much about. However, their support over the forum was reactive and helpful, just to have this mentioned, too. Anyway, at the end, it worked and sounded satisfying all together. And it was my main music setup for a couple of months.

    Now I got my Touch back, together with my "big" hifi-chain. Just to play around, I first attached the USBridge to it instead of the Touch. It just sounded great, very dynamic, very well defined, airy, relaxed and powerfull. No surprise though, I did not expect anything else from my "big" setup.

    Anyway, I switched to the Touch. Mainly, because the Touch has a display and particularly one feature I like, which is, that my DAC and the Touch communicate in a way, that I can use the remote control of the DAC to skip tracks forward, avoiding me to have lunch with my smartphone on the table.

    So, I attached the Touch EDO over USB. And I actually expected it to sound just the same as the USBridge. At the end, I thought, Bits are Bits. And clock timing shortcomings (aka jitter) are no big problem anymore, as long as the through-output (bandwidth) is fast and responsive enough, since USB-Audio got asynchronous, and so the signal is anyway buffered and clocked in the DAC and not anymore in the source. Right?

    I first thought, that it was my mood making me feel that the sound was compressed, narrow, with thinner bass, voices that were not in the foreground, and just everything sounding less involving.

    However, I did the test and switched a couple of times between the USBridge and the Touch. Of course, both of them over USB and with volume settings on the squeezeboxes always at 100%.

    To my surprise (and disappointment...) I am convinced now that the USBridge sounds significantly better than my Touch. Instruments and voices are much better defined and separated, foreground voices are actually foreground, soundstage is wider and more transparent, bass is clearly more distinguishable, timbre of instruments is more natural.

    Strangely I get the impression, that the Touch sounds louder with the same volume set at the amplifier... This makes me think that there is a chance that the problem lies in a setting and not in the hardware. Is there any chance, that the server or the Touch modify the digital information before it gets fed into the DAC?

    Don't get me wrong: It sounds great already with the Touch. Anyway, USBridge sounds really better here.

    Anyway, I still believe that (asynchronous) Bits should be just Bits if the signal gets delivered without being altered, aka "bitperfect". And that the difference resulting of a uncoupled USB-Port in comparison to a "normal" PC-USB-port or the one on the Touch should, if ever, give only a subtle difference in terms of end result in sound quality.

    And I'd like to use the convenience of the Touch...

    So maybe somebody can give me hint about what setting could be wrong on my Touch in order to make it compress the music...?
    Last edited by diego; 2021-07-27 at 03:00.

  2. #2
    Senior Member
    Join Date
    Feb 2011
    Location
    Cheshire, UK
    Posts
    6,167
    Quote Originally Posted by diego View Post
    Hi there everybody!


    Long story short: Why does the "Touch" with Enhanced Digital Output over USB sound compressed and narrow compared side-by-side to the USBridge? Both playing obviously at 100% volume on the Squeezebox Server and Client - Side. Is there a setting I have overseen...?


    The long version:

    I used the Touch with EDO for many years, with a (rather) nice hifi-chain behind it.

    And I was believing that this was "as good as it gets".

    Then I was away from home for some months and had no access to my beloved Touch and hifi-system. So, I searched a temporary solution: Not too bad sounding but not too expensive. I got myself a "USBridge" from Allo based on "Sparky" (and attached it to a nice hifi-setup, however many levels cheaper than the previous one). I have no idea of this Sparky-kind of gear, however, I guess this is some kind of experimental minimalist computer, much like what's more well known as "Raspberry Pi", combined with an additional board festering just one USB - Port that is supposed to be uncoupled from "noisy" electronics, re-clocked and "clean". Whatever that means. And it has Squeezelite on it and therefore works as a squeezebox client. It was a true pain i. t. a. to get it configured tough... hours of trial and error, rebooting etc. until I found the right parameters to get my (temporary) DAC to work communicate right with the USBridge over asynchronous USB audio 2.0. And instructions that are understandable for a non-linux-coder as me are obviously nothing that "Allo" would care much about. However, their support over the forum was reactive and helpful, just to have this mentioned, too. Anyway, at the end, it worked and sounded satisfying all together. And it was my main music setup for a couple of months.

    Now I got my Touch back, together with my "big" hifi-chain. Just to play around, I first attached the USBridge to it instead of the Touch. It just sounded great, very dynamic, very well defined, airy, relaxed and powerfull. No surprise though, I did not expect anything else from my "big" setup.

    Anyway, I switched to the Touch. Mainly, because the Touch has a display and particularly one feature I like, which is, that my DAC and the Touch communicate in a way, that I can use the remote control of the DAC to skip tracks forward, avoiding me to have lunch with my smartphone on the table.

    So, I attached the Touch EDO over USB. And I actually expected it to sound just the same as the USBridge. At the end, I thought, Bits are Bits. And clock timing shortcomings (aka jitter) are no big problem anymore, as long as the through-output (bandwidth) is fast and responsive enough, since USB-Audio got asynchronous, and so the signal is anyway buffered and clocked in the DAC and not anymore in the source. Right?

    I first thought, that it was my mood making me feel that the sound was compressed, narrow, with thinner bass, voices that were not in the foreground, and just everything sounding less involving.

    However, I did the test and switched a couple of times between the USBridge and the Touch. Of course, both of them over USB and with volume settings on the squeezeboxes always at 100%.

    To my surprise (and disappointment...) I am convinced now that the USBridge sounds significantly better than my Touch. Instruments and voices are much better defined and separated, foreground voices are actually foreground, soundstage is wider and more transparent, bass is clearly more distinguishable, timbre of instruments is more natural.

    Strangely I get the impression, that the Touch sounds louder with the same volume set at the amplifier... This makes me think that there is a chance that the problem lies in a setting and not in the hardware. Is there any chance, that the server or the Touch modify the digital information before it gets fed into the DAC?

    Don't get me wrong: It sounds great already with the Touch. Anyway, USBridge sounds really better here.

    Anyway, I still believe that (asynchronous) Bits should be just Bits if the signal gets delivered without being altered, aka "bitperfect". And that the difference resulting of a uncoupled USB-Port in comparison to a "normal" PC-USB-port or the one on the Touch should, if ever, give only a subtle difference in terms of end result in sound quality.

    And I'd like to use the convenience of the Touch...

    So maybe somebody can give me hint about what setting could be wrong on my Touch in order to make it compress the music...?
    First thought. Are they really at the same volume level?
    Jim
    https://jukeradio.double6.net


    VB2.4 storage QNAP TS419p (NFS)
    Living Room Joggler & Pi4/Khadas -> Onkyo TXNR686 -> Celestion F20s
    Office Joggler & Pi3 -> Denon RCD N8 -> Celestion F10s
    Dining Room SB Radio
    Bedroom (Bedside) Pi Zero+DAC ->ToppingTP21 ->AKG Headphones
    Bedroom (TV) & Bathroom SB Touch ->Denon AVR ->Mordaunt Short M10s + Kef ceiling speakers
    Guest Room Joggler > Topping Amp -> Wharfedale Modus Cubes

  3. #3
    Senior Member
    Join Date
    Oct 2010
    Posts
    150
    Quote Originally Posted by d6jg View Post
    First thought. Are they really at the same volume level?
    Well this was my first thought, too. However, yes, I set the the volume always to 100% (as I regulate the volume with my preamp). I believe that 100% is the only setting that makes sure that LMS sends the digital pcm information to the client and the latter to the dac just as it is found on my flac-files.

    I doublechecked this several times while doing this comparison. Always 100%. However, as I wrote, I got the impressum that the Touch sounded slightly louder. Which is indeed strange. However, it might be just an impression.

    I rather think by now, that the USB-port at the Touch, that can also deliver (a small amout of) power, probably mixes with the power supply of the DAC when connected (or the grounds connect together), making the DAC operate with noisy power, which might explain that the DA-conversion is not as precise as it can be.

    Anyway, I remain curious to know if someone else knows this kind of issues and maybe also a solution to it...?

  4. #4
    Quote Originally Posted by diego View Post
    Well this was my first thought, too. However, yes, I set the the volume always to 100% (as I regulate the volume with my preamp). I believe that 100% is the only setting that makes sure that LMS sends the digital pcm information to the client and the latter to the dac just as it is found on my flac-files.

    I doublechecked this several times while doing this comparison. Always 100%. However, as I wrote, I got the impressum that the Touch sounded slightly louder. Which is indeed strange. However, it might be just an impression.

    I rather think by now, that the USB-port at the Touch, that can also deliver (a small amout of) power, probably mixes with the power supply of the DAC when connected (or the grounds connect together), making the DAC operate with noisy power, which might explain that the DA-conversion is not as precise as it can be.

    Anyway, I remain curious to know if someone else knows this kind of issues and maybe also a solution to it...?
    I don't think it is power related. My guess would be that "full volume" either isn't exactly the same, or the Touch does something different, I've never had one so I don't know how they work or sound. I guess one way to test their respective output would be to record the output from the DAC or feed it into an oscillioscope.

  5. #5
    Senior Member
    Join Date
    Feb 2011
    Location
    Cheshire, UK
    Posts
    6,167
    Quote Originally Posted by diego View Post
    Well this was my first thought, too. However, yes, I set the the volume always to 100% (as I regulate the volume with my preamp). I believe that 100% is the only setting that makes sure that LMS sends the digital pcm information to the client and the latter to the dac just as it is found on my flac-files.

    I doublechecked this several times while doing this comparison. Always 100%. However, as I wrote, I got the impressum that the Touch sounded slightly louder. Which is indeed strange. However, it might be just an impression.

    I rather think by now, that the USB-port at the Touch, that can also deliver (a small amout of) power, probably mixes with the power supply of the DAC when connected (or the grounds connect together), making the DAC operate with noisy power, which might explain that the DA-conversion is not as precise as it can be.

    Anyway, I remain curious to know if someone else knows this kind of issues and maybe also a solution to it...?
    But whatĺs the setting in Alsamixer on the USBbridge? That affects the volume at the digital level before output via USB.
    Jim
    https://jukeradio.double6.net


    VB2.4 storage QNAP TS419p (NFS)
    Living Room Joggler & Pi4/Khadas -> Onkyo TXNR686 -> Celestion F20s
    Office Joggler & Pi3 -> Denon RCD N8 -> Celestion F10s
    Dining Room SB Radio
    Bedroom (Bedside) Pi Zero+DAC ->ToppingTP21 ->AKG Headphones
    Bedroom (TV) & Bathroom SB Touch ->Denon AVR ->Mordaunt Short M10s + Kef ceiling speakers
    Guest Room Joggler > Topping Amp -> Wharfedale Modus Cubes

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