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Sibilance Issue

Discussion in 'McIntosh Audio' started by beej, Jun 30, 2018.

  1. beej

    beej Proud BaPa of G, A and AJ Subscriber

    Messages:
    2,887
    Location:
    Southeastern Virginia
    My setup:
    Amp: MC250
    Pramp: C-26
    Turntables: Tech SL-1200 MkII, Pio PL-9 (multiple carts used on each)
    Speakers: EPI-100S and Klipsch KG-2s

    Cave.18x14, carpeted, EPIs in n/e + n/w corners, KG2s in s/w + s/e corners. Setup is in 5' X 6' closet w/ample ventilation. When I had the home built I had speaker wire run from the closet to the 4 corners. I have zip cord pigtails running from the pre to speaker cable and from the speakers to the speaker cable.

    Issue is I'm getting sibilance varying from barely noticeable to clearly there from both speaker pairs regardless of source. Carts are properly aligned, vtf and a/s correct. (Also getting some noticeable sib from cassette deck and tuner as well). I'm getting some sib through my Sennheiser 280s (not the best, I know). Very pronounced in America's I Need You, Crosby, Stills & Nash Marrakesh Express and a little less so on Gordon Lightfoot's Sundown.

    I've done an A/K search and haven't come up with much. Outside A/K I've seen a couple of references to a suspected cause being pigtails that don't 'match' cabling. Not sure about how legit that is.

    Any and all thoughts welcome here. Thanks.
     

     

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  2. Pio1980

    Pio1980 AK Member Subscriber

    Messages:
    26,482
    Location:
    Angel Station, Alabama
    Tried cleaning and working the interconnects? Particularly between preamp and amp, also work all switches and pots on preamp and amp.
     
    chef free likes this.
  3. TSmith8605

    TSmith8605 Senile Member Subscriber

    Messages:
    786
    Location:
    Sunnyvale, CA
    Systematic substitution and testing can usually isolate a problem to a specific component. The part of your post that I put in bold eliminates everything but the line level portion of the C26 and the MC250 as those are always there when you hear the problem. The other possibility is that nothing is wrong with your system and you're just hearing poorly engineered recordings.

    To finalize the process-of-elimination, you could substitute another pre-amp in place of the C26 keeping everything else the same to see if that fixes the problem. If not, put the C26 back in and substitute a different power amp.

    Have the C26 and / or MC250 been restored / recapped / cleaned, etc.?

    Also, if you have access to someone else's system that is known to working well, you could take the three records you cited to that system and see if you still hear the problem. If so, likely the problem originated in the recording studio.
     
  4. twiiii

    twiiii Addicted Member

    Messages:
    6,222
    Location:
    west Texas
    My early 2100's were a little edgy compared to my 275's. After a year or so there were a couple of updates that lowered the IM distortion quite a bit. MY old 2505 had the same issue but was updated for me at a Mac clinic, which helped. I still have the 2505 driving some of my headphones and it does a great job. Its not as analytical as the monitor amps in my C-34, but everything considered it stands up well against my 206 driving electrostatic headphones.
     
  5. kevzep

    kevzep Its all about the Music Subscriber

    This is what my reply was going to be too. I would look at this first.
    I would add, average pressings, ingrained dust/dirt/muck, the kind that cannot easily cleaned off records....
    The inconsistency in vinyl is pretty much why I don't listen to it very often these days...
     
  6. c_dk

    c_dk Addicted Member

    Messages:
    6,240
    Location:
    West Michigan
    Typically sibilance issues stem from mechanical issues........overheated voice coil allows a coil or two to comes loose and rattle. Phono cartridge mistracking causes the stylus to clip off the waveform is most often the issue.

    I wonder in this case if he is clipping the MC250. I do not know the impedence curves of the speakers but would not be surprised if running two pair it would drop to 2 ohms. The amp is 45 years old, under stress would not be surprised if he isn't draining the current out of the amp.......even if he is using the 2 ohm taps of the autoformer.
     

     

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  7. Pio1980

    Pio1980 AK Member Subscriber

    Messages:
    26,482
    Location:
    Angel Station, Alabama
    This has always been the problem with vinyl. Best thoroughly cleaned before play, especially if history is unknown. Next, production values and skills vary widely, dynamics get squashed and capricious EQ choices abound. What is lost or butchered cannot be recovered.
     
    Bill Ferris likes this.
  8. cajunpepe

    cajunpepe New Member

    Messages:
    41
    Ssssssorry to hear you are having issssssues.
     
  9. ron-c

    ron-c AK Subscriber Subscriber

    Messages:
    8,207
    Location:
    N. Ca.
    Does the system play a CD cleanly? If so that eliminates a lot.

    Ron-C
     
    Bill Ferris and Pio1980 like this.
  10. ddude003

    ddude003 New Member

    Not knowing much about your listening room acoustics, treatments and/or eq, could it be the unused set of speakers effecting the acoustics??? If you are playing both sets of speakers at the same time then there could be some other issues to look at with something like Room EQ aka REW...
     
    Last edited: Jul 5, 2018
  11. beej

    beej Proud BaPa of G, A and AJ Subscriber

    Messages:
    2,887
    Location:
    Southeastern Virginia
    Thanks guys - appreciate the input. Let me provide some measure of update as I'm still working my way through the various options. Both the C26 and MC250 received Terry DeWick audio path updates 18 months ago. I've switched carts multiple times and have confirmed proper alignment on all of them. Not a great deal of difference in result. I won't discount the room acoustics although I'd be surprised if this were the case since I'm detecting sibilance (although it seems not quite as much) through headphones. I've not yet cleaned all of the interconnects or worked all of the pots and switches but am getting there. I've played one speaker pair, the other speaker pair and both - no real difference. With respect to the LPs themselves I just finished listening to Phil Collins No Jacket Required - Sussudio. I don't recall Phil emphasizing his Ss to that degree before. I'm not done working the issue. Just thought I'd provide an update. Thanks again.
     

     

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  12. damacman

    damacman Blown and Injected Subscriber

    Messages:
    8,601
    Location:
    Gilbert, AZ
    Did you try what ron-c suggested above?
     
  13. kevzep

    kevzep Its all about the Music Subscriber

    Listen to the same album on Vinyl and then CD, this will tell you where you need to be looking....
     
    Pio1980 likes this.

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