My subwoofer hates my turntable

Discussion in 'Audio Hardware' started by Dennis0675, Jan 6, 2015.

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  1. Dennis0675

    Dennis0675 Hyperactive! Thread Starter

    Location:
    Ohio
    I have a REL sub that only produces a bad feedback or flutter no mater what setting, input or combination of both I have it set on.

    I have literally set it up in a different room from the than the turntable so I don't think isolation is the problem.

    I am going from the TT to a Music fidelity phono stage to a Denon AVR 980 to a B&K amp.

    There are three ways to connect to the REL. .1/lef input, low level input (both go directly from the Denon as the 5.1 surround option) and a high level input that connects to the left and right channel on the B&K.

    I am thinking that the problem as to be in the Denon. Anyone know of an adjustment in the setting in the Denon that could make the REL work the Turntable?
     
  2. gregr

    gregr Forum Resident

    Location:
    MA
    I'm no expert, but could it be a subsonics problem? Does the phono stage have a filter for subsonics?
     
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  3. Dennis0675

    Dennis0675 Hyperactive! Thread Starter

    Location:
    Ohio
    I'm pretty sure it just as input for MC or MM and on on/off. I recently added the phono stage rather than using the internal one on the Denon in hopes that would make the correction. It certainly sounds much better but did nothing to help the sub.
     
  4. quadjoe

    quadjoe Senior Member

    Check your crossover frequency for your sub-woofer on your Denon. I have a AVR 4311Ci, and you can adjust the crossover frequency at which the receiver outputs the low frequencies to the sub. I have mine set to 80Hz, and my turntable is about 5 feet from the sub. I've had no issues at all. From your original post, though, I'm guessing you've done all of that. Let me ask you this: Are all of the various connections (.1 lef, high level, etc.) connected at once? If so, perhaps you're getting double the signal to the REL (I also have an REL sub, love it) causing some sort of overload or distortion. Try using only one, if that's the case.
     
  5. JBStephens

    JBStephens I don't "like", "share", "tweet", or CARE. In Memoriam

    Location:
    South Mountain, NC
    Well, there's a difference between "feedback" and "flutter". If it happens on ONLY vinyl playback and not other souces, I suggest it's subsonics, in which case you'd need a subsonic filter.
     
  6. PIEP

    PIEP Well-Known Member

    Location:
    Firenze, Italy
    I don't think is a sub problem, even if it doesn't help.
    What kind of turntable? Have you take the cover off from the tt?
    Try to put the tt on the floor, put a stone under tt, or a rubber, polistirene sheet,
    have you a hummin' Grado cartridge? Try another tt, like a never hummin' Dual ,
    for example... or a Shure crtrdg .... :whistle:
     
    Last edited: Jan 7, 2015
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  7. Ghostworld

    Ghostworld Senior Member

    Location:
    US
    No "Subsonic Filter" switch on your Denon?

    I just looked on Denon's website, there is no "Denon AVR 980" You have that model number right?

    There is an AVR 890 which does have a phono input, but no subsonic filter (nice work, Denon) in which case you're going to have to find one and add it. You could try this. High pass filter set at 30hz.

    http://www.amazon.com/FMOD-Crossover-Pair-High-Pass/dp/B0006N41CO/ref=cm_cr_pr_sims_t
     
    Last edited: Jan 7, 2015
  8. PIEP

    PIEP Well-Known Member

    Location:
    Firenze, Italy
    Subsonic Filter does not matter... it is a problem of the turntable,
    but what is the tt's brand?
     
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  9. Ghostworld

    Ghostworld Senior Member

    Location:
    US
    Wait a minute. The sub is in another room from your stereo, or the turntable is in a different room from the stereo? If you're using super long cable from your turntable to your stereo, all kinds of weird things happen.
     
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  10. ggergm

    ggergm I don't believe in Santa Claus or MoFi

    Location:
    Minnesota
    A subsonic filter would definitely help. The Harrison Lab piece linked to upthread will do the job but it's a bit cheesy. I've used them often, and have Harrison Labs filters on my whole house audio system right now to limit the bass to inwall speakers. Just know they aren't audiophile products. But you can't beat them for the price.

    You say you've tried different locations for the turntable. I have found three things help that you might not have tried. If your stand is on castors, those have to go. Next, see if you can set up your turntable next to an exterior wall and not in the corner. Keeping it out of the corner will lower the amount of bass shaking the stand. Then put something between the back of your cabinet and the wall itself. Most of the time I've used a coffee mug. It will give your stand two points of support and make it more stable. My experience has been that feedback problems more often come from the stand the turntable is on than the turntable itself.
     
    Last edited: Jan 7, 2015
  11. Could be a possibility. How long are your cables and what are they?

    Still sounds like a feedback problem. If that's the case you need to isolate the TT (proper mounting) or work on tuning resonance frequency to a low enough point it's not an issue.
     
  12. Dennis0675

    Dennis0675 Hyperactive! Thread Starter

    Location:
    Ohio
    It's an AVR 988, I don't see anything that says subsonic filter.
     
  13. Dennis0675

    Dennis0675 Hyperactive! Thread Starter

    Location:
    Ohio
    It's just a Pro-ject debut carbon with the Acrylic platter and a Ortofon 2m Blue.
     
  14. Dennis0675

    Dennis0675 Hyperactive! Thread Starter

    Location:
    Ohio
    The .1/lef input, low level input cable is about six foot. The high level input that connects to the left and right channel on the B&K is pretty long, at least ten ft. I think I have successfully made sure that anything coming out of the sub is not is not making it to the TT.
     
  15. Drew769

    Drew769 Buyer of s*** I never knew I lacked

    Location:
    NJ
    I had the same problem recently with my 2WQ subs and my TT. Solved 100% with an isolation base of a 2 1/4 inch thick Boos Block and some isolation blocks similar to the Mapleshade ones.
     
  16. Ham Sandwich

    Ham Sandwich Forum Resident

    Location:
    Sherwood, OR, USA
    I'll place my bet on motor rumble subsonics. 60 Hz, 120 Hz, maybe even some 30 Hz.
     
  17. bresna

    bresna Senior Member

    Location:
    York, Maine
    I had that problem and I solved it by making a isolation turntable shelf out of two 1.25" thick pieces of butcher block held apart by 4 superballs that I got at a local toy store. I partially drilled 1" holes on the top of the lower shelf and the bottom of the upper and dropped the super balls in the holes. My problem went away.

    BTW, the worst offender was Pink Floyd's "Comfortably Numb" from my original "The Wall" LP. :)
     
  18. Kyhl

    Kyhl On break

    Location:
    Savage
    The question was, how long is the interconnect between the turntable and the phonostage? The sub wire length won't matter. The TT signal is very weak and suscptible to electronic interference. Also, long runs of cable raise the cables capacitance which will greatly affet the sound of your TT.

    Also, can you give more discription to your use of "feedback" and "flutter"?

    I asume the AVR has a tuner. Does the sub act the same when playing music off the radio or a CD?

    I am also leaning towards a rumble filter but more info is needed to get to the bottom of this.
     
  19. Dennis0675

    Dennis0675 Hyperactive! Thread Starter

    Location:
    Ohio
    I can only describe the feedback or flutter as a wild vibration that makes one feel as if the sub is going to crack if the signal isn't shut off. Its like it is having a spasm and sounds nothing like the bass on a recording. It is an angry low rumble. It certainly sounds like feedback but the volume can be so low that barely anything can be heard from the front speakers and the rumble will be faint but still an uncontrolled sound. It works perfectly with every other signal source, Just not the TT.

    The only thing going from the TT to the Phonostage is an RCA with the ground wire connected at the TT and the Phono stage, it is about three ft. and then it is an RCA from the phonostage to the receiver.

    I got in touch with Denon support and their thought is that is was a grounding issue but I don't know what could be done additionally to ground anything. The ground wire is connected and the whole thing is going through a monster power strip. Not the best but certainly grounded.

    I went into the setup menu and switched the set up on the subwoofer from LFE to LFE + main, that did nothing. I didn't connect to the .1/lef input, low level input only the high level input but I don't think that will make any difference.

    I am way into getting an isolation table or a better turntable with a much more substantial plinth (like a VPI classic) but I really think there is an issue with the Denon. with noise coming from even the lowest levels of volume and not at all close to the table, I don't see how it could be making it to the table to feedback.
     
  20. James Glennon

    James Glennon Senior Member

    Location:
    Dublin, Ireland
    What have you got your turntable sitting on?

    JG
     
  21. ggergm

    ggergm I don't believe in Santa Claus or MoFi

    Location:
    Minnesota
    The Denon, outside of not having filtering, which is not unusual, has nothing to do with your problem. To prove that to yourself, borrow another amp from a friend or a store. It will be easy to prove or disprove if the Denon is at fault.

    If it really is acoustic feedback, your problem is purely mechanical, not electrical. You have to break that feedback loop of sub > turntable > stylus > sub > turntable > stylus > sub etc. Do that and your problem will disappear.
     
    Last edited: Jan 7, 2015
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  22. ggergm

    ggergm I don't believe in Santa Claus or MoFi

    Location:
    Minnesota
    I, too, would like to know this. When you are playing your turntable, if you put your hand on the side or top of your cabinet, do you feel the bass? If you do, there could be your problem. Try my tricks in my post upthread to solve the acoustic feedback.

    I don't want to pull rank but I owned a stereo store for 21 years and have 30 years selling hi-fi. I solved acoustic feedback, and the related problem of footfalls causing records to skip, in customer's homes dozens of times. You will be shocked at the difference squeezing a coffee mug between a solid part of the the rack (not a flimsy back panel if that's all it has) and the wall will make. It keeps the cabinet from vibrating wildly.
     
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  23. Dennis0675

    Dennis0675 Hyperactive! Thread Starter

    Location:
    Ohio
    I appreciate the help. The table is on top of a heavy wood cabinet. It is really more of a hutch that the tt sits on top of. And yes...hard wood floors. So yes, the chance of vibrations making it to the table does sound probable. Again with the levels of volume being almost non existent I don't think the vibrations are being created that could transfer to the needle.

    On either side of the table and the cabinet I have two Paradigm studio 100's that I give quite a bit of power and volume to and I don't get any feedback. I did when I really pushed it but I moved the speakers forward and pushed that table back and that solved it.

    I obviously haven't been using the sub and don't really miss it. I like it for the Phil Bombs on the Web casts or listening to the files on the computer. It is just a drag to remember to unplug the sub when I go back to records. I know one day I will forget and damage the sub.
     
  24. James Glennon

    James Glennon Senior Member

    Location:
    Dublin, Ireland
    The reason I asked is because I too use a REL subwoofer. My REL is about 4ft away from the turntable which sits atop an Origin Live turntable stand. I am using Barry Diament's method of having the turntable shelf sitting on three roller bearings for isolation. See below...

    [​IMG]

    JG
     
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  25. ggergm

    ggergm I don't believe in Santa Claus or MoFi

    Location:
    Minnesota
    Dennis, are you knowledgeable enough to tell the difference between a 60 Hz buzz and a lower frequency howl? A 60 Hz buzz is often what you hear at a club or a show when the guitar player plugs in. It will also be the buzz you hear when you disconnect your turntable's ground wire. Acoustic feedback is at a lower frequency, around 15 Hz. It's a rumble more than a buzz.

    If your problem is at 60 Hz, then your problem is electrical. If it's at 15 Hz, it's mechanical.
     
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