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Unsolvable Woofer Pumping (Phono only)

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branden_8091

Member
I'm at a loss for trying to find the source of my "woofer pumping." It's most noteworthy when playing something that is mostly/all treble, and the woofers of my Focal Aria 906s are going nuts (inaudibly, of course). Turntable is a Debut Carbon with Ortofon 2M Blue.

Initially I was told it's an isolation problem, so I better isolated my TT, even put it right on the concrete floor to test! Next I thought maybe a problem with the TT itself, so tried a couple others, no change. So I figured it must be acoustic feedback, as with the TT stopped and stylus on a record, I could produce woofer pumping by tapping on certain parts of my stand...but it is also not this! I turned off my amplifier and recorded from the pre-out to a Tascam digital recorder and played that back afterwards and the pumping STILL happened! So I tried an Schiit Mani phono stage, no change in woofer pumping...I was sure it had to be my pre-amp...

So a local audiophile came over with a couple of pre-amps and we tried those. The only time the problem went away was when the subsonic filter that one had was engaged. So, I've ordered some Harrison Labs "FMODs" (20Hz high pass) to see if they will help. If they do, I may order a KAB RF1 one day...but don't want to spend that much if I don't have to.

Any other ideas on what could cause this?!

tl;dr: Woofer pumping not caused by isolation, acoustic feedback, phono/preamp or a compliance issue...what's happening?!
 
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Is there an issue with the motor, or with the pulley? Or with the main bearing? A stethoscope might be helpful in tracking down the source. Run the motor without the belt, spin the platter without the belt, and look very carefully at the belt.
 
Nat said:
Is there an issue with the motor, or with the pulley? Or with the main bearing? A stethoscope might be helpful in tracking down the source. Run the motor without the belt, spin the platter without the belt, and look very carefully at the belt.
Click to expand...

I can check that soon, I'll have to get my hands on a stethoscope first. I highly doubt it though as I've tried with a few turntables and the problem remains.
 
It's sub-sonic problem. I noticed the Pro-ject 2Xperience I once owned had that problem. No heavy platform or other isolation devices helped. Only using the sub-sonic filter worked. Your Harrison Lab device should do the job.

BTW... just outta curiosity, did you find the resonance frequency using a test record?
 
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Mr Boochie said:
It's sub-sonic problem. I noticed the Pro-ject 2Xperince I once owned had that problem. No heavy platform or other isolation devices helped. Only using the sub-sonic filter worked. Your Harrison Lab device should do the job.

BTW... just outta curiosity, do you test the resonance frequency using a test record?
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Hmmm, do you think it could be a combination of that along with very efficient speakers such as my Focals? This problem only presented itself when I got them...but seems to happen with every turntable I try.

And no I do not, I don't yet own a test record.
 
jbrainey said:
Well...it's close enough to cause feedback issues but you're the expert so why ask here?
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It's not though...as even with the speakers off, I made a recording and played it back and the woofer pumping persisted. I shouldn't have to turn down bass to diminish the problem, because it's still there, just not visible.
 
If I understand you to be saying you've used several turntables and had the same problem, and you you've played recordings you made of the turntable playing while the speakers were off, that leaves a couple of questions - you don't appear to be using high compliance cartridges with high mass arms, so if there isn't a physical problem with the tables, that leaves the preamp as the likely source.
 
branden_8091 said:
TT is not too close to the speakers, but you're right about the bass...but I like a bit of bass so I guess I'll have to use a filter.
Click to expand...

This is sub-sonic issue. My bet is you have excessive woofer travel, just running the stylus on the inner runout area of a record. I think my Pro-ject was picking up rumble from the platter or the spindle bearing. As no isolation device(s) between the turntable and shelf or speakers helped.

It must be that. I have zero issues with my Sony and Technics direct drive turntables. They must have better inherent isolation between their motors and the tonearm. Quieter motors. Both are placed exactly the same positions as where the Pro-ject once sat.
 
Nat said:
If I understand you to be saying you've used several turntables and had the same problem, and you you've played recordings you made of the turntable playing while the speakers were off, that leaves a couple of questions - you don't appear to be using high compliance cartridges with high mass arms, so if there isn't a physical problem with the tables, that leaves the preamp as the likely source.
Click to expand...
I also tried other pre-amps, as mentioned in the start of the thread. Nothing seems to help except the subsonic filter that one of the tried preamps had built in. It was a higher end Yamaha.
 
Mr Boochie said:
This is sub-sonic issue. My bet is you have excessive woofer travel, just running the stylus on the inner runout area of a record. I think my Pro-ject was picking up rumble from the platter or the spindle bearing. As no isolation device(s) between the turntable and shelf or speakers helped.

It must be that. I have zero issues with my Sony and Technics direct drive turntables. They must have better inherent isolation between their motors and the tonearm. Quieter motors. Both are placed exactly the same positions as where the Pro-ject once sat.
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You may be on to something there! I wonder why this happens with other turntables though. Unless they all for some strange reason have the same issue. I'm thinking of upgrading most of my system, the TT I'm eyeing now is a Music Hall mmf-7.3. I realize they're made in the same factory as Pro-Ject, but a world of difference exists between them I believe.
 
When you say 'I've tried it with a few turntables and the problem still remains' and 'it seems to happen with every turntable I try', that suggests to me that the turntable is not the problem. What amp are you using - it sounds like you have a preamp and power amp, and that only using a preamp with a subsonic filter solves the problem. But it may actually just be masking the problem. If your amp is unstable, any low frequency may cause it to act up. That's not a good thing, and probably wasn't how it behaved when new. You may have some sort of problem there.
Are the Focals ported - that will definitely make them more likely to pump.
And no one has asked about the frequency of the pumping - is it uniform, is it violent, is is on again and off again?
 
branden_8091 said:
You may be on to something there! I wonder why this happens with other turntables though. Unless they all for some strange reason have the same issue. I'm thinking of upgrading most of my system, the TT I'm eyeing now is a Music Hall mmf-7.3. I realize they're made in the same factory as Pro-Ject, but a world of difference exists between them I believe.
Click to expand...

Knowing the resonance frequency of your tonearm + cartridge is important for this reason. Get a used Shure Type III, Type IV, or Type V Obstacle Course test record. It has many other testing features besides resonance frequency. Very easy to use. Good instructions.

Headshell and cartridge weight effects the resonance frequency. Along with many other factors. Compliance of tonearm and stylus, weight of tonearm, etc.

For my setup... 8-12 Hz seems the best resonance frequency. For good bass response, yet least amount of feedback or excessive woofer movement.

https://www.amazon.com/Audio-Obstacle-Course-Trackability-Cartridges/dp/B008FFVU7O

https://www.ebay.com/sch/i.html?_fr...A0.H0.TRS0&_nkw=Shure+audio+obstacle&_sacat=0
 
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gadget73 said:
another thing that will cause this is a poor match between the arm and the cartridge. Not that I know anything about this specific arm and cartridge but if you know the arm effective mass and the cartridge compliance you can plug it into the calc at vinylengine to see if its a bad idea.

https://www.vinylengine.com/cartridge_resonance_evaluator.php
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I have a Pro-Ject Debut Carbon DC with a 2M blue cart. Considering it comes stock with a 2M red...I don't think it's a poor match.
 
Nat said:
When you say 'I've tried it with a few turntables and the problem still remains' and 'it seems to happen with every turntable I try', that suggests to me that the turntable is not the problem. What amp are you using - it sounds like you have a preamp and power amp, and that only using a preamp with a subsonic filter solves the problem. But it may actually just be masking the problem. If your amp is unstable, any low frequency may cause it to act up. That's not a good thing, and probably wasn't how it behaved when new. You may have some sort of problem there.
Are the Focals ported - that will definitely make them more likely to pump.
And no one has asked about the frequency of the pumping - is it uniform, is it violent, is is on again and off again?
Click to expand...
I have an AMC 2100 amp, using a rebuilt (by a reputable guy with good parts) Marantz 2240 as my pre-amp. This issue happens with both though, as in if I used the Marantz 2240 on its own as an amp. It's fairly uniform...here is a video I took and uploaded to Youtube. They of course, muted the sound. It is of the intro to Hotel California, guitars only, at a regular listening volume...loudness function turned on (the issue is still there without isn't this bad until higher volumes) https://youtu.be/sZG5fL4HwN8
 
Mr Boochie said:
Knowing the resonance frequency of your tonearm + cartridge is important for this reason. Get a used Shure Type III, Type IV, or Type V Obstacle Course test record. It has many other testing features besides resonance frequency. Very easy to use. Good instructions.

For my setup... 8-12 Hz seems the best resonance frequency. For good bass response, yet least amount of feedback or excessive woofer movement.

https://www.amazon.com/Audio-Obstacle-Course-Trackability-Cartridges/dp/B008FFVU7O

https://www.ebay.com/sch/i.html?_fr...A0.H0.TRS0&_nkw=Shure+audio+obstacle&_sacat=0
Click to expand...
Thank you! Will look into a test record.
 
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