Sonic Frontiers SFD-1mk2 Vintage DAC for $750 That Stomps Most Modern DACs

Discussion in 'Digital: DACs, USB converters, decrapifiers' started by purr1n, Nov 9, 2015.

  1. Ntbm3

    Ntbm3 Friend

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    Mine is quieter than my Gungnir both xlr our. But same as my Bifrost 2 SE out.
     
  2. lehmanhill

    lehmanhill Almost "Made"

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    I think there may be a problem. It sounds great, but the volume is lower then my other dacs. Out of curiosity, I dug out a Linkwitz Lab test CD that has a 20 - 20 kHz Pink Noise track. Using an old Radio Shack noise meter on a tripod, I measured the A weighted sound level for the SFD-1 and Pavane, both with coax in and balanced out. Specs say that the SFD-1 should be approximately 5V for a normal CD and balanced out. The Pavane is rated at 4 Vrms balanced out. Assuming the SFD-1 is talking peak to peak, those are within 1/2 dB.

    The Radio Shack meter had the SFD-1 at 61 dBA and the Pavane at 68 dBA for the same preamp level. R2R dacs output depends on the input or reference voltage. Because the SFD-1 sounds good, just quiet, I wonder if the reference voltage is slipping over 30 years? Does anyone know if the reference voltage is generated inside or outside the UltraAnalog chip? It could be the output stage too.

    I guess I will have to contact PartsConnexion for more info and, maybe, see if HiFi Heaven will accept a return if its impossible to fix.
     
  3. murray

    murray Friend

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    Does it have a PMD100 filter chip for HDCD support? This can result in a 6B (or so) drop on a normal Red Book CD signal. My Adcom dac seems to do that. It has to allow for boosting HDCD in peak extend mode.
     
  4. purr1n

    purr1n Desire for betterer is endless.

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    5Vpp is about 1.8Vrms.

    1.8Vrms to 4Vrms is about 7db less output.
     
  5. lehmanhill

    lehmanhill Almost "Made"

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    It does have the HDCD support, but I was quoting the non-HDCD balanced spec which is half the HDCD number.

    You are correct. I mis-stated the spec. Actually, they don't say what kind of volts. The spec for output voltage is:

    Output Voltage - Approx. 5.0 Volts (non-HDCD/balanced)

    According to the pdf on the UltraAnalog chip shared by @ChaChaRealSmooth, the chip outputs +/- 5V which is not p-p but is about 3.5 Vrms or about 1dB below 4 Vrms. But then, with the PMD100 filter and other elements in the output stage, I guess I don't really know voltage it should put out.
     
  6. rikkitik

    rikkitik New

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    The seemingly (and real) lower output is, in fact, normal. It is/was a frustrating requirement for the PMD HDCD implementation. The standard was a 6db level drop in "redbook" playback. IIRC, it may be mentioned in the manual (if you can dig one up).
    If you look up old reviews of HDCD, players and DAC's, I believe you will find it mentioned in a couple. Some Pacific Microsonics "thing", maybe to make HDCD seem more dramatic.
    (I've owned a few SF DAC's)
     
    Last edited: Jul 15, 2020
  7. rikkitik

    rikkitik New

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    '95 Stereophile review of PS Audio Ultralink, "When decoding non-HDCD discs, the 6dB of attenuation called for by the HDCD license is performed in the digital domain by the PMD100."
     
  8. murray

    murray Friend

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    I'm pretty sure that is to provide headroom for the HDCD Peak Extend boosting. My DAC effectively uses the bottom 17 out of 18 bits for Red Book data, so that it can boost the levels for the Peak Extend. Hence the effect provides boost by "scaling everything else down". I came to that conclusion after checking voltages, resistor values and schematics. That's the only way I could reconcile the maths.
     
  9. Scott Kramer

    Scott Kramer Friend

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    Screen Shot 2020-07-16 at 12.00.08 AM.jpg
    I seem to remember on my adcom gcd-750 hdcd's were always quieter. Normal CD's were louder.

    You guys had me curious so I used the latest hdcd.exe to convert a disk just now (created larger 24bit/44 files)... much quieter overall (seems like more than 6db, not sure).
     

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    Last edited: Jul 15, 2020
  10. lehmanhill

    lehmanhill Almost "Made"

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    Thank you all for that information. I don't care if it is quieter or needs more volume, I just care that something isn't failing, especially something that you can't replace like one of these esoteric chips. As I said, it sounds great, so I will just enjoy it.
     
  11. lehmanhill

    lehmanhill Almost "Made"

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    Tying up loose ends.

    This is for anyone wanting to compare results or check how their SFD-1 compares to mine. It may also explain Sonic Frontiers specs.

    I found at test track from PS Audio that is 1 kHz, 0 dB. Perfect for checking output levels of a dac. Thank you PS Audio. It has an equal signal on both channels. The track is linked below, if anyone wants it.

    https://www.dropbox.com/s/vknsyly6f993vqc/11 Sine Wave 1khz.wav?dl=0

    I put the track on my LMS server and selected no volume adjustment and 100% level. Then I measured the AC voltage (rms) at the analog output of the SFD-1 with a multimeter.

    All of these are for non HDCD as the test track is a 1 minute wav file.

    Single ended - spec = approx. 2.5 volts
    measured - 0.992 Vrms or +/-1.4 V or 2.8 Vp-p

    Balanced - spec = approx. 5 volts
    measured - 1.989 Vrms or +/- 2.8 V or 5.6 Vp-p

    Although it is not what I expected, it appears that Sonic Frontiers specs are peak to peak voltage.

    And for me, I'm happy to learn that my SFD-1 is OK.

    Jac
     
  12. Scott Kramer

    Scott Kramer Friend

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    IMG_0153.jpg
    IMG_0070.PNG
    @lehmanhill damn you so you have me hunting down my HDCD's! Processing them properly...

    Sounds amazing 24/44.1 into Yggdrasil, just such kick at least on this one! How is the SFD with actual HDCD content?

    PS this King Crimson version is really good, and vinyl for camparison.

    Even wrote a quickie script to do the whole disk.
     

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    Last edited: Aug 14, 2020
  13. lehmanhill

    lehmanhill Almost "Made"

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    What's really funny is that you have only yourself to blame for this. I wasn't even aware that you could convert files to HDCD until you posted about it in post #210. Before I bought the SFD, I didn't even know about HDCD. When I figured out the details, I decided that I wasn't going down that road, but when I decided to sell the SFD, I put the conversion program information in the sale post and got questions about it. That all refers back to you.

    So, I don't have any HDCD content, converted or otherwise and haven't heard it on the SFD. Sorry. The SFD is still available (self serving plug), although I may just keep it for a future project as it is a awfully nice DAC.
     
  14. Luckbad

    Luckbad Traded in a unicorn for a Corolla

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    You might consider just keeping it if you paid your asking price for it, otherwise you will lose some cash. I try not to call out prices, but consider it advice from someone who has owned several of these DACs (I tend to sell them reluctantly each time, and usually because I don't want money stuck in a nice transport for them):

    - For a stock SFD-1 MKII, you can generally get $600-$800
    - For an SE+ modded SFD-1 MKII, you can generally get $700-$900

    The only time I've paid your original asking price for one was direct from Parts Connexion with a clean bill of health and fresh SE+ mods, shipped from Canada to California.

    Modifiers to price: If it has SE+ mods, the price goes up. If it has AES input, the price goes up. If it's in really good condition, the price goes up. If it has nice tubes, the price goes up. If it's been to Parts Connexion recently, the price goes up. If someone desperately wants one, you get lucky and sell high. If it smells like smoke, the price goes down.
     
  15. YMO

    YMO Chief Fun Officer

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    Considering @lehmanhill you posted this made me think there was something wrong with you unit. I was considering sending you a PM for an offer, but that post made me changed my mind. I think others are thinking of the same as well after reading that post.

    Edit: Looks like since your unit has HDCD they lower the db output on purpose. My bad for not reading it right.
     
    Last edited: Aug 15, 2020
  16. lehmanhill

    lehmanhill Almost "Made"

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    Just curious, what post gave you the impression there was something wrong? Post #203 when I first learned about the lower output? Or a later one? Post #212 clears up the output level as correct to spec. I'm just wondering if I need to do something more to clarify that its OK.
     
  17. YMO

    YMO Chief Fun Officer

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    Your posts cleared it up, thanks.
     
  18. Azimuth

    Azimuth FKA rtaylor76, Friend

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    I think you can put the HDCD code to notify if a file is HDCD or not, I doubt you can encode to HDCD because that takes specialized mastering equipment and choices such as peak extension and low level range extend, etc. I think you had you have some Pacific Microsonics equipment for such things.

    Basically you can't get a 20-bit stream from a 16-bit file. And if you did have a 24-bit file, why would you encode to HDCD anyway? You have the full 24-bit file.
     
  19. lehmanhill

    lehmanhill Almost "Made"

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    That's very interesting. I looked at hifishark to research pricing and there were 2 units sold, one in Canada and one in Ukraine, that sold in the last month with asking prices of more than $1000. Both were the same spec as mine. That said, there was one sold in Canada in Dec 19 that was $600.

    I have thought about DIYing an AES input. It seems like it would be pretty easy. Do you think a DIY AES still adds value?

    In the end, I think you are right. Even if prices are occasionally higher than your numbers, I can't assume they will hold up for such a relatively narrow market. I'm going to leave it up for sale, but look at keeping it. It's totally worth keeping if I can put it to use.
     
  20. A Child of the Jago

    A Child of the Jago Facebook Friend

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    Interested in this DAC and am wondering if anyone can chip in with its synergy with either Black Widow or ECP DSHA-3F or how they feel they might pair.

    My chain will be: Eitr -> SFD-1 MK2 -> BW or 3F -> Verite

    Sound-wise I'm particularly interested in warmth, visceral bass, rich tonality and musicality - although the SFD-1 isn't NOS that's the way I lean. On that point, I'm also wondering how this fairs against the newer Metrum DACs - Onyx and Pavane - or the Holo Audio Spring.
     

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