crazy speaker pulsating with turntable

[brightpav]

Hey folks,

I’ve got an ongoing issue with my setup that I can’t seem to figure out so I thought I’d turn to the experts here at AK! The details of my gear are below but here’s an explanation of the issue:

Long story short, the woofers in my speakers are violently pulsating back and forth both visibly and audibly when playing records. This only happens when listening to vinyl and is not limited to a single recording nor does it happen with every record.

And here’s the real doozy; it even happens when no music is playing!

A video is worth a thousand words in this instance so take a look at the link below to see it in action:

Video: https://www.dropbox.com/s/tvtxu19x8c5t0k0/Speaker_Vibrate.mov?dl=0

In this video I have the tone arm down, needle set in the run-in groove of an LP (Cecil Taylor - Looking Ahead if you’re curious.) The platter is not spinning.

As I raise the volume on the receiver, the speaker starts to vibrate back and forth aggressively and makes a terrible noise. As you can imagine this sometimes happens when music is playing as well, when a volume threshold is reached I assume. It’s worth noting that the behavior is worse in the right speaker than the left.

Some things:

• The TT is decoupled from the speakers and receiver on its own shelving unit
• TT connections are properly seated & TT is grounded to the receiver
• Speakers are on the floor, roughly 8ft apart (best I can do)
• Floor is hardwood with a crawl space beneath
• Electrical is updated but core building was built in the 20s

My first thought is feedback or maybe something to do with electrical. The thing that perplexes me is that this happens when there is no music playing, but the needle is simply on a record!

As for any other possible audio “interference” there is a slight hum that sounds like a ground loop to me, that can fluctuate better or worse. This is only audible on phono and the needle is on the record. Though the electrical is updated who knows if it’s been fully re-wired and what’s going on in the other flats.

Things I’ve tried:

• Flipped the plug to try to solve any grounding issues
• Reseated all connections
• Auditioned different records and different volumes
• Added a small slab of wood under the turntable to attempt to further decouple
• Moved speakers further away from TT

No dice.

I’m stumped and hope someone out there might have a clue. As mentioned my gear setup is below. Appreciate any thoughts as always.

Thanks!

—

Receiver: Harman Kardon 330 C
Speakers: Klipsch Heresy I
Turntable: Music Hall MMF 2.2
Cartridge/stylus: Nagaoka MP 110

 

[homebrew]

Sounds like feedback or turntable rumble. Do you have another source like CD? Do you have the same issues with that? If not, then it's your turntable.

 

[vonclod]

A rumble filter would likely end it, I use a KAB https://www.kabusa.com/frameset.htm?/rf1.htm, I bought one years ago..money well spent.
Weird that it does it when not spinning, maybe try another cartridge if you can.

 

[Montycat]

That's totally acoustic feedback. You need better isolation between speakers and the turntable.

Stands or isolation blocks for the speakers, placement of them away from walls etc. Turntable on a wall mounted shelf preferably on a load bearing wall. Or give me the speakers; I have some Minimus 7 I'll trade straight across.

 

[brightpav]

That's totally acoustic feedback. You need better isolation between speakers and the turntable.

Stands or isolation blocks for the speakers, placement of them away from walls etc. Turntable on a wall mounted shelf preferably on a load bearing wall. Or give me the speakers; I have some Minimus 7 I'll trade straight across.

Thanks!

That’s what I was figuring but even when there isn’t any audio playing I can still get feedback? The stylus/cartridge are essentially a microphone I suppose but I thought there would need to be some audio to pick up, no?

What about Vibrapods under the TT?
Any isolation blocks you recommend?

 

[brightpav]

A rumble filter would likely end it, I use a KAB https://www.kabusa.com/frameset.htm?/rf1.htm, I bought one years ago..money well spent.
Weird that it does it when not spinning, maybe try another cartridge if you can.

That’s the most perplexing part. Even without audio!

 

[Montycat]

You can try various homebrew things. I don't have feedback problems so never really had to do anything and don't have specific recommendations.

There are DIY sandbox or scooter/kids bike/wheelbarrow inner tube things for example. However, start at the speakers, isolating at the source. They create the low frequencies that the very sensitive cartridge picks up.

Try some foam rubber under them as a start. You can get more elaborate or expensive but start simple.

 

[vonclod]

That’s the most perplexing part. Even without audio!

Yes, that is weird, some kind of resonance/feedback, Monty has some good suggestions. I use some pieces of foam rubber from an exercise mat, under my TT feet, it helped isolate the TT from the room.

 

[Greenie]

Yes, that is weird, some kind of resonance/feedback, Monty has some good suggestions. I use some pieces of foam rubber from an exercise mat, under my TT feet, it helped isolate the TT from the room.

Well even if the TTs not turning or playing music it's cartridge is still acting as a basic microphone/vibration sensor. By placing it on a disc you are using your record to magnify any low level feedback (eg subsonic or very low level hum), and pick up any noise if the motor is running but not engaged (unlikely).

An old Garrard of mine years ago did something similar, at high volume levels you could get howling eventually after several seconds.
The plinths on some TTs from the 70s/80s seemed almost designed to to this, but they looked nice or were cheap to make. And of course all amps had a rumble filter back then!

 

[w1jim]

Here’s a silly question - have you removed the shipping screws?

 

[rothwellaudio]

...but even when there isn’t any audio playing I can still get feedback?

That’s the most perplexing part. Even without audio!

You don't need any audio playing to get feedback - why would you?

Yes, that is weird, some kind of resonance/feedback...

There's nothing weird about it - the turntable will pick up any vibrations and feed them back to the speakers. The "wobble" you see is due to the arm/cartridge resonance. A cartridge of different compliance would shift the resonant frequency and maybe reduce the effect.

Well even if the TTs not turning or playing music it's cartridge is still acting as a basic microphone/vibration sensor. By placing it on a disc you are using your record to magnify any low level feedback (eg subsonic or very low level hum), and pick up any noise if the motor is running but not engaged (unlikely).

Yes, that's what's happening. A subsonic filter like the one mentioned by vonclod would probably cure it. Some phonostages have subsonic filters built in, some permanently on, some switchable. They used to be quite common on phonostages but seem to be less common now.

 

[Montycat]

You can get the Art Dj Pre for a lot less and it has a low cut filter. I'm not sure how effective it would be in your circumstance but it might work.

http://www.artproaudio.com/product/djpre-ii-phono-preamplifier/

 

[bimasta]

When you say "no music playing", do you mean any music? No music from any source? The room is silent?

 

[bimasta]

When you say "no music playing", do you mean any music? No music from any source? The room is silent?

 

[Greenie]

You can get the Art Dj Pre for a lot less and it has a low cut filter. I'm not sure how effective it would be in your circumstance but it might work.

http://www.artproaudio.com/product/djpre-ii-phono-preamplifier/

I have two, the low cut filter works well with rumble generated by an old, well used Garrard AP76 I gave away recently.

I've tried it on TTs which generate no low frequency problems and it doesn't seem to affect the sound so the cutoff is sensible.

 

[cartop]

I had the same issue and I tried everything to no avail. Then someone said to try and removing the dust cover and I thought how could that help but guess what it did. I don't know if your TT has the cover on or off but if it can be removed try it and see if it helps. Don't ask me how it helps because I am not really sure but it did.

 

[Lavane]

I had a Realistic Lab 500 direct drive table years ago that would do this as well. Even with the tone arm parked not playing. Moving the deck and speakers would help some, but never cured the problem. Instead of buying a sub sonic filter I ditched the turntable for a Technics.

 

[ttbccw]

Does it still do it if the cartridge is disconnected? That would confirm the feedback if it doesn't.

 

[classic carl]

Speakers are on the floor, roughly 8ft apart (best I can do)

How close is the turntable to the speakers? Can you move it further away?

 

[brightpav]

Here’s a silly question - have you removed the shipping screws?

Not silly. No such thing! Yes, the shipping screws are removed.