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woofer pumping

Today I tried to play some vinyl through my new setup (Dynaudio C1 speakers and VTL MB-450 amps/VTL 5.5 pre) and I noticed a large amount of woofer pumping (Whenever I listen through the CD player or Squeezebox the woofers barely move at decent listening volumes).

My turntable is a Technics SL1200, cartridge is AudioTechnica 440 MLa and the phono pre is a Cambridge Audio 640P. Nothing fancy but the woofer pumping is worrying me and I'd like to reduce it. It's currently sitting on an Ikea Expedit so it's not the best for isolating vibration since just tapping it immediately makes the woofer travel more.

I was thinking of getting a 4" maple platform from Mapleshade with the Isoblock footers. Any other suggestions?
jibbonacci
apachef1
164 posts
 
IT SHOULD HELP BUT REALLY IT SOUNDS LIKE THE ROOM AND SETUP MAY BE ON THE SMALL SIDE. THE TT IS MOST LIKELY PICKING UP SOUND WAVES IN THE ROOM.

I CANT COMMENT ON THE BENEFITS OF A 2" VS 4" PLATFORM FOR YOUR TT. IT COULD BE SITTING ON A SLAB OF CONCRETE AND THE TT WILL STILL PICK UP SOUND WAVES IN YOUR ROOM.

START WITH THE 2" AND HOPEFULLY IT WILL TAME IT DOWN ENOUGH FOR YOU TO LISTEN TO YOUR VINYL UNTIL YOU MOVE INTO THE NEW SPACE

DIRECT DRIVE TT ARE NICE AND EAST TO USE BUT YOU DO END UP WITH SOME SOUND QUALITY ISSUES FOR THE ADDED CONVENIENCES
steveaustin
57 posts
 
I second (third?) the KAB Rumble filter suggestion. Really no sonic compromise I'm able to discern when using it -- no more woofer-pumping, and the 'table is also actually now less vulnerable to footfalls (no more tiptoeing around when listening to vinyl).

Another benefit besides the obvious reduction/elimination of woofer pumping is that your amp (and sub(s) if applicable) will no longer waste a lot of energy and effort trying to reproduce those inaudible low frequencies that cause those woofers to frantically pump away. No point in having your amp struggle to reproduce something you can't hear (and can only 'see').

Got mine here on Audiogon used for around $150 - turned out to be a great investment for me. Any concern I had about adding something into the chain and possibly degrading the delicate phono signal has been far outweighed by the more effortless overall presentation I'm getting when listening to records.
jibbonacci OP
31 posts
 
Thanks for the suggestions everyone... I think I may try the KAB rumble filter since it would be a fairly cheap fix if it actually works for me.
newbee
4,751 posts
 
No one has mentioned that the probable cause of the woofer pumping is a mis-match between the cartridge and the arm. This will do it every time. It is a arm mass/cartridge compliance issue you should investigate.

There is nothing wrong with using a subsonic filter but it better to fix the underlying problem than to add a band aid, I think. The problem still exists, you are just masking it. Additive is usually subtractive in audio.

FWIW, just a thought.
steveaustin
57 posts
 
Good points, Newbee. I hadn't considered that the arm on Jibbonacci's Technics may present a mis-match with the Audio Technica cartridge he's using.
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