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Thread: Raspberry Pi 4 and Caiman SEG

  1. #1
    Join Date: Oct 2008

    Location: Southampton, UK and Nicosia, Cyprus

    Posts: 1,139

    Default Raspberry Pi 4 and Caiman SEG

    I have not posted here in ages and only recently returned to the Squeezebox forum.

    I have restored Squeezeboxes to my home network and moved Logitech Media Server from an ageing PC to a Raspberry PI 4 running PiCorePlayer. It works extremely well.

    In Southampton I have an old 7510 DAC which has no USB input. In Nicosia I have an original Caiman with Gator board fitted DIY. That too still works well.

    My plan is, in due course, to get a new Caiman SEG and connect the Raspberry Pi 4 directly to it by USB.

    Has anyone in these parts experience that combination? In the other place the opinion was offered that the USB out from a Raspberry Pi 3 was a bit rough, but from an rPi4 was excellent. The Topping E30 is known and common in the Squeezebox forum, and PiCorePlayer has an adjusted USB output option for it, but Standacs are virtually unknown.

    Does anyone here use PiCorePlayer via USB to a Caiman? Can anyone shed light on the need to have various USB audio output configurations? Surely USB out is USB out!

    Here is my Raspberry Pi 4 in a KODI case next to my router with a CD to show the scale. Tiny, tiny, tiny!

    IMG_20220131_124458125.jpg

    My Flac library of ripped CDs is now on a 128GB button sized USB flash drive, and that's my complete server! It runs on less than 10W.

    I am presently using a Google Chromecast Audio dongle as a virtual Squeezebox optically coupled to the 7510 DAC, but if I get the USB connection right I can lose that extra bit of hardware and put the Raspberry Pi behind the TV next to the DAC.

    What can anyone tell me?
    Brian

    In Southampton: Raspberry Pi 4 running PiCorePlayer, Beresford Caiman SEG, Quad 77 Int Amp and CD Player, AVI Neutron 4, Sennheiser HD25 headphones.
    In Nicosia: Small Format HTPC, Beresford 7520 ,Quad 405-2, Quart 980s German Tower Loudspeakers.

  2. #2
    Join Date: Jan 2011

    Location: Wiltshire

    Posts: 194
    I'm Alastair.

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    I used the USB output from a Pi3 to a Caiman SEG a few years ago and it worked fine but the Allo Digione Pro SPDIF was better. I replaced the SEG with a Topping D90 and the Pi3 with a Pi4 and spent quite some money on a reclocker and expensive USB cables only to conclude USB is not the way to go unless you need very high sampling rates or are willing to spend serious money. I now have a Pi2AES hat in my Pi4 feeding I2S to my DAC but SPDIF is almost as good. With the SEG, the Digione is worth a try.

    Sent from my SM-G988B using Tapatalk
    Cheers

    Alastair

    RPI4/PI2AES running PiCorePlayer/LMS-> AQ Carbon AES -> Topping D90 DAC-> Khozomo Passive Pre-Amp -> 4x Temple Audio Monoblocks powered by 2xLiFePO batteries->Van Damme Black Bi-Wired to B&W 804 Nautilus and Sommer Carbokab 225 Interconnects

  3. #3
    Join Date: Oct 2008

    Location: Southampton, UK and Nicosia, Cyprus

    Posts: 1,139

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    Thanks Alp.

    Stan is about to send to me one of his latest batch of his latest DAC. My 7510 is close to 20 years old!

    Experts on https://forums.slimdevices.com/ offer the opinion that whereas the USB output from a Pi3 could be rough that from the Pi4 is extremely good.

    Time will tell. Maybe Stan has some comments even now.
    Brian

    In Southampton: Raspberry Pi 4 running PiCorePlayer, Beresford Caiman SEG, Quad 77 Int Amp and CD Player, AVI Neutron 4, Sennheiser HD25 headphones.
    In Nicosia: Small Format HTPC, Beresford 7520 ,Quad 405-2, Quart 980s German Tower Loudspeakers.

  4. #4
    Join Date: Jun 2015

    Location: London/Durham

    Posts: 6,869
    I'm Lawrence.

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    Can't comment on the individual DAC in question, but from my experience older DACs have weak internal USB to SPDIF convertors and you can't judge USB as a medium by listening only to them. A decent external convertor will upgrade them and keep them sounding their best with any source.

    I've read reviews of more recent DACs where the USB was said to be the best sounding input, so it depends on the individual DAC and implementation.

    Sent from my BKL-L09 using Tapatalk

  5. #5
    Join Date: Aug 2021

    Location: South West

    Posts: 151
    I'm Stuart.

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    Can’t answer the specific question re Picore player to a Caiman but I have used a RPi4 for about 18 months now, with a variety of DACs.
    I previously used the USB connection and about 6 months ago, bought a 2nd hand Allo Digione Signature, allowing me to connect to my DAC via co-ax.
    Over Xmas, I put together another RPi4 streamer and whilst it was in my possession, couldn’t resist doing an A/B between the 2 RPis. Both playing exactly the same FLAC tracks, into the same DAC (one USB, the other co-ax), into the same amp and speakers.
    I’m not going to say that I couldn’t hear a difference, but quite honestly it was so small a difference (in favour of the co-ax connection) that I’d be more than happy reverting to USB if I had to.
    I suspect that part of this may be down to the quality of the USB connection on my DAC - a fairly new Schiit Modius.

  6. #6
    Join Date: Feb 2008

    Location: http://www.homehifi.co.uk

    Posts: 6,288

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    There are so many variables to think of, I have started to get paranoid about the quality of the individual audio files that I have in my library. I'll probably do a write up on various technical aspects of things that I found out compared to what is generally talked about. But I might end up turning others paranoid as well...

    The reason I typed the above is because the quality of the original file will affect the quality of the playback. Less forgiving decoding can quickly make a bad quality file sound bad, whilst a more forgiving decoding system can still make a poor audio file sound reasonably acceptable. Whether you use USB or optical is down to personal taste in any carefully assembled audio system. I myself prefer playing back some tunes via USB, whilst others sound nicer to me from optical. I don't so much use "better" as my reference, but "nicer".

  7. #7
    Join Date: Oct 2008

    Location: Southampton, UK and Nicosia, Cyprus

    Posts: 1,139

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    There is one issue using the SEG and a Raspbery Pi and PiCorePlayer via USB , the cause and remedy you will see in the link below.

    When connecting by USB the SEG has to be running before the rPi is started up (or at least before the player component "Squeezelite" is started.) If not the DAC cannot see the Pi.

    https://docs.picoreplayer.org/projec...-from-usb-dac/

    The remedy requires command line adjustments. I will leave it as it is - my Linux knowledge is not great and I might break something I cannot mend! I hope some future upgrade of PiCorePlayer will have the remedy written in. In the meantime I will remember to turn the DAC on first - though both SEG and Pi I leave on 24/7

    This issue occurs with at least some other USB DACs.
    Brian

    In Southampton: Raspberry Pi 4 running PiCorePlayer, Beresford Caiman SEG, Quad 77 Int Amp and CD Player, AVI Neutron 4, Sennheiser HD25 headphones.
    In Nicosia: Small Format HTPC, Beresford 7520 ,Quad 405-2, Quart 980s German Tower Loudspeakers.

  8. #8
    Join Date: Jun 2015

    Location: London/Durham

    Posts: 6,869
    I'm Lawrence.

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    Quote Originally Posted by StanleyB View Post
    There are so many variables to think of, I have started to get paranoid about the quality of the individual audio files that I have in my library. I'll probably do a write up on various technical aspects of things that I found out compared to what is generally talked about. But I might end up turning others paranoid as well...

    The reason I typed the above is because the quality of the original file will affect the quality of the playback. Less forgiving decoding can quickly make a bad quality file sound bad, whilst a more forgiving decoding system can still make a poor audio file sound reasonably acceptable. Whether you use USB or optical is down to personal taste in any carefully assembled audio system. I myself prefer playing back some tunes via USB, whilst others sound nicer to me from optical. I don't so much use "better" as my reference, but "nicer".
    I'd be interested to know your thoughts on this. I only discovered recently when playing around with the config file on my Zen that there are various compression rates for Flac (1-9?), and the default is usually 5. I reduced mine to 1 and thought it sounded marginally better.

    There's also an optional volume equaliser setting (and I'm talking about the music signal, not metadata) which would be even worse I imagine.

    The former caused some controversy on the Wam when I posted (I think I was in a minority of 1 in thinking there's an issue). I don't think anyone believed me about the latter, every time I tried to explain they kept saying don't worry it's just metadata (but that has a separate setting of its own in the config file).

    Sent from my BKL-L09 using Tapatalk

  9. #9
    Join Date: Feb 2008

    Location: http://www.homehifi.co.uk

    Posts: 6,288

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    I mentioned numerous times in the past that there is an audible difference in the compression levels of FLAC. That's why I don't use any compression if I am the one creating the FLAC file from for example a CD.
    The volume level thing is often referred to as Replay Gain. It is stored in the metadata. But not all replay gain setting programs use the same method to calculate that value. And some even modifies the actual audio file instead of just adding the replay gain value to the metadata. The best known program for that out there is MP4Gain - https://mp4gain.com/mp4gain
    I prefer to use the replay gain function in MediaMonkey, which doesn't modify the audio file.
    But "correcting" the replay gain doesn't mean that you get an improved signal output. So any clipped signal peaks will still be clipped after the replay gain is set. However, it is a useful metadata marker. Many ICE (in car entertainment) systems can now read that replay gain value and adjust the sound output of each track so that you don't have to fight with the volume control to keep the perceived audio level at more or less the same strength.

  10. #10
    Join Date: Oct 2008

    Location: Southampton, UK and Nicosia, Cyprus

    Posts: 1,139

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    Quote Originally Posted by StanleyB View Post
    I mentioned numerous times in the past that there is an audible difference in the compression levels of FLAC. That's why I don't use any compression if I am the one creating the FLAC file from for example a CD.
    I don't understand the point of creating a FLAC file with Zero compression. Why not just leave it as a WAW file (or similar uncompressed format) if the file is not shrunk for easier storage? Maybe there are systems that will not play WAW or whatever, or maybe it's a question of attaching metadata.

    There is of course confusion in some people's minds about the various sorts of compression:

    1. FLAC and similar formats that are like ZIP files unzipping back to where they were;

    2. the lossy formats like MP3 that decrease musical resolution to save storage space;

    3. and dynamic compression that (by analogue or digital process) reduces the loud to soft ratio permitted in the file and on replay.

    It seems to me that dynamic compression sucks the life out of the music faster than the lossy compression used in MP3 and similar. Radio stations apply different levels of dynamic compression - some like Radio Swiss Classic - are only MP3 128kb/s but maintain an open sound when playing CDs, presumably because they are gentle with dynamic compression.
    Last edited by Labarum; 14-03-2022 at 07:43.
    Brian

    In Southampton: Raspberry Pi 4 running PiCorePlayer, Beresford Caiman SEG, Quad 77 Int Amp and CD Player, AVI Neutron 4, Sennheiser HD25 headphones.
    In Nicosia: Small Format HTPC, Beresford 7520 ,Quad 405-2, Quart 980s German Tower Loudspeakers.

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