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  1. #1

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    Default High Frequency Distortion

    I recently purchased a Musical Fidelity A3cr preamp, a few days later I got a good deal on a second hand Raysonic CD128. After settling in for a few days, I started noticing a disturbing problem, higher frequency sounds like female vocals, organs, guitars etc, were starting to come through with a slight amount of distortion. It reminded me of the effect that results when you listen to a low bit rate MP3, not as extreme but in the same vein. I found that it is not as audible on some CDs as it is on others. I began to try to narrow down the issue, I tried playing the same CDs on my Oppo player and got the same distortion. That meant it didn't appear to be the new player or the CD input in the preamp as I have the Oppo connected via the SACD input. I then tested out some LPs and found that no matter what I played there was none of the distortion that I had heard listening to CDs. I even tried playing the same albums on both CD and LP and found that the distortion was present on the CD but not the LP. I have the TT connected to the preamp via the Aux1 input as it's going through an external phono preamp. I then tested the TT using all the other line level inputs with the same result, no distortion. After all this, it seems like the preamp is over-amplifying the line level signals coming from certain CDs. I wondering if anyone has every experienced this sort of problem and if this sounds like something that would need professional service to fix.

    Thanks
    Mains - Chario Constellation Delphinus
    Subs - Rel T5 x 2
    Amplification - Denon POA S-10 Mono Blocks
    Pre Amp - BAT VK-3i
    CD - Raysonic CD128
    SACD/DVDA- Denon DVD 5910 w/ Underwood Level One Mod
    TT - Pro-Ject RPM 9.1 w/ Ortofon 2M Black Cartidge, TT Weights Super Ring
    Phono Stage - Jolida JD9 w/ Mods

  2. #2

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    Does the distortion come thru both channels? Have you tried different IC's?
    'Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."

  3. #3

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    Default

    It does come through both channels and I tried different IC's between the pre and power amp as well on the CD player to the preamp and got the same result. I even got a little crazy and picked up a power conditioner from Best Buy (30 money back return!) to see if it had anything to do with the AC, no difference.

  4. #4

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    In that case, it would seem as though your pre has an issue. Time for a trip to the repair shop.
    'Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."

  5. #5

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    I was afraid of that. Thanks for the help. I guess these are the pitfalls of buying used equipment. :(
    Mains - Chario Constellation Delphinus
    Subs - Rel T5 x 2
    Amplification - Denon POA S-10 Mono Blocks
    Pre Amp - BAT VK-3i
    CD - Raysonic CD128
    SACD/DVDA- Denon DVD 5910 w/ Underwood Level One Mod
    TT - Pro-Ject RPM 9.1 w/ Ortofon 2M Black Cartidge, TT Weights Super Ring
    Phono Stage - Jolida JD9 w/ Mods

  6. #6

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    Maybe try a different input on the A3CR?

    Source: Squeezebox Touch/CIA Power Supply
    DAC: Benchmark DAC/PRE
    Linestage: Placette RVC Passive
    Power Amp: Parasound HCA-1500A
    Speakers: Harbeth Compact 7ES-3 Monitor
    Subwoofer: SVS PB12-NSD

  7. #7

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    Default

    I had an issue like this. The recording was hot, and the particular CDP had
    a higher output than most. A Rotel pre mixed with that CDP had some
    harsh sounds on, you guessed it, female vocals. I dumped the Rotel preamp
    because of it, and later with my Parasound had the same problem. That
    pre had a little red input overload light blinking when I heard the problem.
    That pre had a input gain adjustment that fixed it! My other CDP didn't
    have the problem. The cd was Nora Jones. There's a couple of cuts from that
    album that push it a bit. Amy Winehouse is recorded so hot that the whole
    thing sounds like crap.
    "The legitimate powers of government extend to such acts only as are injurious to others. But it does me no injury for my neighbour to say there are twenty gods, or no god. It neither picks my pocket nor breaks my leg." --Thomas Jefferson

  8. #8

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    I'm looking at in-line attenuators right now. I guy is sending me a set of Harrison Labs attenuators for free so I'll see how it effects the issue. I was also looking at Rothwell attenuators. I’m glad to hear that I'm not the only one experiencing this problem. I'll let you guys know what happens after I try them out.

    Oh yes, I did try all the inputs on the pre and got the same result, except phono of course.
    Last edited by Bass_Pedal; 03-24-2009 at 03:04 PM.

  9. #9

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    Default Sweet!

    So today I received a pair of Harrison Labs attenuators in the mail. Since the I was getting them for free from someone I didn't know I didn't think it was cool to ask him what kind they were, beggars can't be choosers! So as I opened the package I wasn't sure which ones I would get... the 3db version... hey it's better than nothing! So I tried them out. Guess what? All my distortion problems, thus far are gone. I tried all the test discs I had played before and all but the new U2 album (which appears to have been mastered for a full on dance party!!) are clean and distortion free! So now that I have confirmed that the issue is gain coming in from the CD player, does anyone have any suggestions as to a better attenuator or are there other possible solutions. I am particularly worried about effecting sound quality.

    Thanks

  10. #10

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    Iíve experienced clipping/distortion from the analog output from a DAC in the past, with very hot recordings. Interestingly, certain tracks on Norah Jones Feels Like Home is one of them. The clipping sounds like fuzziness and hardness in some of the vocals.

    This is not the same as having a gain issue with the preamp though. The preamp issue may be more related to overloading the preamp with the combination of a high output source playing a hot recording (voltage too high). However, it is interesting that both of your CD players produced the same result. What preamp were you using before, and do you still have it for experimentation?

    Although the source and preamp equipment should be able to handle the output voltage of any CD track, these damn super-hot recordings are definitely part of the problem, IMO.
    Polk LS90
    Polk CS400i
    Polk FX500i
    Outlaw LFM-1 Sub
    Polk Monitor 7C (secondary location)
    Pioneer Elite VSX-45TX
    Audiosource Amp Three (2), Amp One/A (1)
    Cambridge Audio C500 Preamp
    Sony 222ES CD/SACD
    MSB Nelson Link III DAC with P1000 Power Supply, Music Hall DAC 25.2
    Squeezebox Classic
    Sony BDP-S1000ES
    JVC DLA-HD250 Projector
    Da-Lite HCCV - 100" Permwall 16:9
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    Panamax 500 DBS
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  11. #11

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    Default

    I thought it was odd that both players caused an issue as well. I hadn't tested my previous preamp until yesterday. I was using a MF A3.2cr before I got the MF A3cr that I'm using now (I prefer the more laid back sound of the A3) When testing the A3.2, I didn't get any of the distortion problems. While I'm happy that the attenuators solved most of the problem, I do find it odd that it is an issue in the first place. My preamp may need to be serviced, but I really don't know what kind of cost that might incur and I’m a little afraid to find out.

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