Isolation Question- getting low frequency feedback

Fishfood

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I'm now using a 12" bass reflex studio monitor and I'm experiencing low frequency feedback that is clear in the lead in and lead out grooves... so I assume it's in the music as well and can explain some of the congestion I'm hearing on some of my recordings.

The turntable (VPI Aries 1) is on a wall shelf, so it's well isolated, but it sits 4 feet behind the left speaker. The feedback increases with volume and decrease if I relocate the speaker. The problem is we live in a small loft space and I've got no where to move anything. The setup has to stay as is.

So my question is: is it the turntable? Can I expect different results from a different turntable (idler, suspended, just a better table)? Or is the issue simply proximity and the LF sound waves being picked up by the cartridge?
 

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I'm now using a 12" bass reflex studio monitor and I'm experiencing low frequency feedback that is clear in the lead in and lead out grooves... so I assume it's in the music as well and can explain some of the congestion I'm hearing on some of my recordings.

The turntable (VPI Aries 1) is on a wall shelf, so it's well isolated, but it sits 4 feet behind the left speaker. The feedback increases with volume and decrease if I relocate the speaker. The problem is we live in a small loft space and I've got no where to move anything. The setup has to stay as is.

So my question is: is it the turntable? Can I expect different results from a different turntable (idler, suspended, just a better table)? Or is the issue simply proximity and the LF sound waves being picked up by the cartridge?
I would expect this to be the airwaves interfering with the turntable. You can try placing the turntable on some soft feet or on springs. UK company Avid even has a unique spring suspension for their turntable.
 

bazelio

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I guess the burning question is, with the proximity to the speaker, is there any isolation that could help?
Isolation would help. The suggestions to damp the speaker as opposed to the table might be a good place to start. I think with VPI, that floppy uni-pivot arm that they use is going to be very susceptible to mechanical interference.
 

AMR / iFi audio

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A straightforward way to see if vibration control will help is to go to the closest hardware shop and get a 1-1,5" thick plywood. Put it under the turntable and listen if it helps.

@bazelio, excellent point about the uni-pivot arm!
 

Fishfood

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A straightforward way to see if vibration control will help is to go to the closest hardware shop and get a 1-1,5" thick plywood. Put it under the turntable and listen if it helps.


Thanks for the suggestion, but shouldn't this be enough isolation with the 1.5" maple shelf on spikes with brass spikes on the turntable side (and the tubes are filled with half lead shot and half sand)? Maybe I need to get a suspended table in here to test to see if the table is just too susceptible.....

IMG_0559.jpeg
 

Leekg

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Have you tried something soft and squishy for isolation, like the VPI HW-40 feet? I see lots of coupling to your wall but no isolation. Unless your wall is concrete its acting like a big drum with your turntable receiving every movement. I don't know the feet under your table - are they providing some squish?
 

Fishfood

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Or maybe the first thing to do is to try an inline subsonic filter just to diagnose. And then get rid of the unipivot. Although I do prefer the sound of it compared to the VPI gambled version of the arm, maybe it's time to move onto a different TT project altogether.
 
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Fishfood

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Have you tried something soft and squishy for isolation, like the VPI HW-40 feet? I see lots of coupling to your wall but no isolation. Unless your wall is concrete its acting like a big drum with your turntable receiving every movement. I don't know the feet under your table - are they providing some squish?

Nothing squishy. I'm also grabbing a shelf and some squash balls, again just to test. None of these ideas are particularly good for the sound but first things first.
 

bazelio

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Thanks for the suggestion, but shouldn't this be enough isolation with the 1.5" maple shelf on spikes with brass spikes on the turntable side (and the tubes are filled with half lead shot and half sand)? Maybe I need to get a suspended table in here to test to see if the table is just too susceptible.....

I think you've already determined that it's not sufficient isolation. Spikes ... Under speaker stands people call them coupling devices, yet under components or shelves the same spikes are referred to as decoupling devices. Amazing! The spikes aren't really helping you, bottom line. They're not necessarily hurting either. But I suspect the TT is coupled to the floor through the wall, and that you simply don't have enough mass to quell the vibes, despite maple, sand and lead shot. That particular wall bracket looks to me like it'd fold under the weight of a high mass table.
 

Fishfood

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I think you've already determined that it's not sufficient isolation. Spikes ... Under speaker stands people call them coupling devices, yet under components or shelves the same spikes are referred to as decoupling devices. Amazing! The spikes aren't really helping you, bottom line. They're not necessarily hurting either. But I suspect the TT is coupled to the floor through the wall, and that you simply don't have enough mass to quell the vibes, despite maple, sand and lead shot. That particular wall bracket looks to me like it'd fold under the weight of a high mass table.

Actually the bracket is anchored with 4 long lag bolts to a post that is attached to a load bearing beam in the ceiling. But your point about the isolation is well taken. I've got some new feet for the table on order. If that makes a dent in it, I'll look to isolate the shelf more. Most likely I'm getting a new table and arm, eventually, because all I read about when I search now is the unipivot being subject to low frequency waves. Don't like the VPI enough to invest in the gimbled version of this arm.
 
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Mike Lavigne

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there is a solution; but it's heavy (near 100 pounds) and very expensive ($10k-$12K retail).

Herzan TS-150 or TS-140. assuming they are on a solid base, they are designed to attenuate low frequency resonance down to .5hz. i use 5 of them (an exotic version of them) in my system. my tt's are near my bass towers, 750 pounds/7' tall with -4- 15" drivers -3db at 7hz and -6db at 3hz. these towers pump out lots of base. i only use the Herzan TS-140 under the turntable closest to my bass towers (the other 4 units are under electronics).

one caution about using active isolation is that it only works under gear which does not have any self noise. if your tt generates resonance of it's own, then that resonance will be picked up by the TS unit's piezo electric sensors and the unit will try to attenuate it. this feedback loop will burn the unit out.

if your floor or rack is not solid, don't bother with thinking about the active approach. it does require some mass and solidity to perform.
 
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Solypsa

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All good advice so far, and yes isolation ( whether engineered such as Herzan or Minus K, etc. ) is the ideal I do feel the turntable may be culpable as well. Lots of people have turntable's between a pair of speakers so its clearly possible. And as awesome as those Diatone's are they aren't exactly pumping out 16hz so take heart - it can be done!
 
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bazelio

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All good advice so far, and yes isolation ( whether engineered such as Herzan or Minus K, etc. ) is the ideal I do feel the turntable may be culpable as well. Lots of people have turntable's between a pair of speakers so its clearly possible. And as awesome as those Diatone's are they aren't exactly pumping out 16hz so take heart - it can be done!
Doesn't the Motus plinth have some internal damped isolation? Now might be a good time for a sales pitch... It is a legitimate step up from the VPI in terms of quality after all.
 

AMR / iFi audio

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Thanks for the suggestion, but shouldn't this be enough isolation with the 1.5" maple shelf on spikes with brass spikes on the turntable side (and the tubes are filled with half lead shot and half sand)? Maybe I need to get a suspended table in here to test to see if the table is just too susceptible.....

View attachment 95548
Oh yeah, that's more than enough. I didn't think it was this solid already :)
Somebody mentioned a subsonic filter for your phono, did you think about that?
 

Fishfood

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Oh yeah, that's more than enough. I didn't think it was this solid already :)
Somebody mentioned a subsonic filter for your phono, did you think about that?

Yeah. I ordered an inexpensive inline subsonic filter just to assess that part of it as well.
 

Solypsa

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Doesn't the Motus plinth have some internal damped isolation? Now might be a good time for a sales pitch... It is a legitimate step up from the VPI in terms of quality after all.
Well now that you bring it up :)

@Fishfood *if* you look at upgrading your VPI please look into the suspended, direct drive turntable made by STST, their Motus IIDQ. STST makes all in house including drive system, well established company, great value. I am their rep...

Pic of a Motus with interior shown:
Screenshot-2018-11-03-at-15.42.57.jpg
 
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Fishfood

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Well now that you bring it up :)

@Fishfood *if* you look at upgrading your VPI please look into the suspended, direct drive turntable made by STST, their Motus IIDQ. STST makes all in house including drive system, well established company, great value. I am their rep...

Pic of a Motus with interior shown:
View attachment 95572

I worship that table! I've been looking at them on the AnaMighty site since I deal with Francois a lot with my cartridge and step up. Definitely will be in touch. Thanks.
 
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