Unsolvable Woofer Pumping (Phono only)


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?!

branden_8091
@mike_in_nc Thanks, I tried several different records. Do you think a record clamp would help? I've been meaning to get one.
Record warp was my first reaction as well.  Is the woofer pumping worst when the tone arm is near the outer edge of the record and best as it moves close to the dead wax?
Well you've certainly taken all the right steps to narrow it down, so good on you. With a lot of the most likely culprits eliminated we are down to only a very few good options left. One being, its perfectly normal flutter, you're just not used to seeing it. Most people with entry level tables have been raised on CD and don't know some amount of this is normal. Not being there we can't know if this is it or not.

Moving on.... your table has a felt mat and let me guess, you're not using a record clamp. So records lay kinda sorta flat. But not really. Problem being, anything other than absolutely flat gets amplified by the time it gets to your speakers by about a hundred thousand times. 

The solution is a record clamp. Not weight, clamp. Specifically, you want one that's cupped on the bottom, or has something like an O-ring going around the outside. Anything to create a space between the record label and the center of the clamp. Then you also want a thin washer, just barely thicker than your mat, that fits over the spindle. The idea being the clamp will press the record down forcing the edges into the platter making the record lay absolutely flat.

A good clamp used like this will almost always be a nice improvement, which since it will also work on future better tables makes it a fine investment no matter what. 

Since you say its noteworthy mostly when just treble this implies to me you don't really notice it with bass-heavy music, which in turn implies to me that whatever flutter you're seeing is no more than normal music level or less. Which to me means perfectly normal, you're just not used to seeing it. But whatever. Try a clamp and see.


@millercarbon Thank you!  I've grown up with both, but my earlier systems weren't as high quality (I started at about 6 years old with some crappy BSR changers).  I can understand that a little bit is normal, but this seems a little excessive to me.  At lower volumes I enjoy the extra musicality the comes from turning on the "loudness" function.  I realize many audiophiles scoff at this, but, whatever. I like it.  Since it turns up lower end a fair amount, the woofers really show this problem then.

I have the acrylic platter, but no weight/clamp...I've been meaning to get one and can see how it would improve my situation.  I'll definitely look into a clamp instead of a weight though! Thanks.

Here is a video of the intro to Hotel California, at a normal listening level, loudness on. https://youtu.be/sZG5fL4HwN8


It’s sounding like this is probably "normal" performance for this table. With an entry-level table that only weighs 12 lbs, you’re not going to get the performance of a topology that costs more and is focused on design elements such as: high mass in the center of the bearing, incorporation of a low friction bearing, or effective damping that help produce low rumble and smooth operation. I don’t think a clamp is going to help. The KAB will work although many purists feel rumble filters like are sonic bandaids. It just depends on what your goals are and budget you’re willing to spend. It doesn’t sound like you want to spend much if the cost of the KAB is daunting to you.
@three_easy_payments I see.  I will more likely go the filter route rather than clamp, at least until I get a better system.  If that needs a clamp then no problem.  I do plan on upgrading my system relatively soon, which is why I'm hesitant to spend on a filter I may end up not needing once I've upgraded.  I have another thread on upgrading if you'd like to chime in on that :)
I can't see myself ever having more than a $10 000 system. My current one has cost me about $4000.
If you do eventually install a high pass (rumble) filter, you might choose a lower frequency roll-off. 10Hz should do it. If your filter has its "knee" at 20Hz, that will affect higher bass frequencies more than is necessary for the effect you desire.

I must say I read your opening remarks, but you went over all the efforts you made rather lightly. At each juncture, I wanted to ask questions. For example, how, after your tapping on the stand caused the woofers to respond, did you rule out an unstable stand as the source of your problem? In the Tascam experiment, are you saying that a recording made from an LP into the Tascam driven by the output of your preamplifier, also induces woofer pumping? What speakers are you using? What is the stated low frequency extension of the speakers? How are they mated to the floor? Carpet or hard surface? Thanks.
@lewm Sorry about the lack of detail, I didn't want to make it too wordy.  I'm new to forums!  Fair enough about the filter.
I ruled out the unstable stand as the problem by putting the turntable right on the concrete (with thin carpet) floor.  And yes that's what I did for the Tascam recording!...speakers are Focal Aria 906.  It seems (based on all the input I've received here and other forums) that this behaviour is normal for ported, bass reflex speakers such as mine.  Especially with a (in the world of hi-fi) an entry level TT.  I bet if I spent the same on my turntable as I did on speakers I wouldn't have this issue (better bearings, motor isolation, etc.).
The low freq of the speakers on the spec sheet is 55Hz, this is well below that though.  They're both on hard surface with focal stands (which have spikes).
Thank you!


Does that table have a dust cover? If it does you should remove it and see if that helps!
Branden, this is called rumble. It is worse in your instance because of your speaker's design, little ported woofers. The enclosures are designed to push those little woofers as low as they can go. The end result is that they have to move farther to have any output down low. 
You have two fixes, a rumble filter or using a subwoofer with a high pass filter for the satellites. The subwoofer is a better solution. With a high pass filter on them your speakers will sound MUCH better and you will get better bass with a subwoofer system. Two subs or more will work best. You have to have a high pass filter for this to work. 
And Branden the low frequency limit is 55 Hz because the woofers are too small to have any significant output below that that you can hear. It does not mean that they do not try to follow the waveform below 55Hz. They will unless you have a low pass filter on them.

Mike
@yogiboy Yes it has one, I’ve tried removing it, no change. Of course, I always play with it up anyay.
Mike,
@mijostyn Ahhhh thank you! Little pieces of this puzzle keep coming in. I can’t afford and don’t have the equipment to drive a subwoofer...but would a more full range (i.e. floor standing) speaker be a better choice when I do decide to upgrade next? That entirely makes sense about the frequency limit as well.
No. A speaker with extended bass response would not help. Most cabinets are ported in one way or another and therefore don’t exert much control over the woofer motion. However such designs in my opinion offer a natural sounding bass response. What you’d want is an acoustic suspension type, with a closed box.  The closed box exerts some back pressure on the woofer cone which inhibits the phenomenon you are observing. But in my opinion such types are less natural sounding in the base. That’s just my opinion. By the way, there are several Inexpensive subwoofers on the market that would cost you less money than replacing your entire speaker system. And I agree with others it would help your problem. Many such subwoofers, in order to remain small in physical size, do use some form of acoustic suspension cabinet. That alone would help.
Might be due to cartridge/tone arm mismatch. Some damping of the tone arm might help also. Something to research I think. I had a similar problem with a tone arm with a well for oil to damp tone arm vertical movement which went dry. There used to be add on devices to accomplish the same thing. Good luck.
newbee, Good point.  But the cure of damping might worsen the disease.  Damping would add mass to the tonearm, and that would drive the resonant frequency downward.  Resonant frequency is inversely proportional to effective mass.  Oil damping, as you mention, might help if it could be applied to the OP's tonearm.
Branden, the woofers in any speaker including subwoofers will still dance to the rumble but with a larger driver in a sealed cabinet it will be much less noticeable at moderate volumes anyway. All records have some rumble built in. You may notice that some records are worse than others.
You would have to have a damaged turntable or an old idler wheel drive for it to rumble that bad. For all of us the only way to keep our main speakers clean is to divert everything under about 100 Hz to subwoofers.
For those of us with two way or one way loudspeakers this is actually critically important even if you do not use a turntable as low bass will Doppler distort everything else the woofer or speaker is trying to reproduce. For those who do not know what Doppler distortion is just have a friend drive by you at 40 MPH leaning on the horn. As the car passes you the horn will change tone. It will go from high to low. That is exactly what is happening when the woofer is flapping back and forth at low frequencies. 

@mijostyn Very interesting.  I don't have any equipment to drive a subwoofer yet, just good old fashion two channel stuff.  A subwoofer will be something to look into in the future possibly!
@lewm I'm just itching to audition some speakers now! Ha ha. I was more asking if a more full range speaker would be about equal to adding a subwoofer now? I'm currently not able to have a subwoofer...and still my heart prefers old fashion two channel setups.
Is there an airport near you??   I had this happen to me years ago...radar interaction I was told...   I had the electrician drop another ground wire....went away.
Branden, I have heard some very incredible systems using small stand mount speakers with subwoofers. You do not need any more than a two channel system to run subwoofers. The amps and crossovers are usually built in. Sure, if you are itching to get new speakers go for it. Focal's aere not shabby loudspeakers and to get a floor stander of that quality will cost a lot. I am an old fashioned two channel guy. Each of two channels has two subwoofers attached to it and my speakers are 7 feet 10 inches tall.
Newbee, cartridge tonearm mismatches can cause a lot of trouble but not like this. If the tonearm is too light the system will feed back when the right base note comes along. If the tone arm is too heavy the tonearm will start shaking when the right warp comes along and can even fly up into the air. When you are about to replace a worn out cartridge start adding pennies to the head shell and see what happens. Oil damping will do absolutely nothing for this problem as the cartridge is doing exactly what it is supposed to be doing, picking up vibration. It is not shaking, jumping off the record or feeding back. Do this. Take your speaker covers off. Put the stylus in any run out groove and turn the volume all the way up. Now look at your woofer dance. 
@stringreen Interesting.  There is one about 15km away...I will try a 'cheater cord' to ground to my house rather than to the pre-amp's grounding point.
@mijostyn I was unaware...I thought subs were generally un-powered. I may be trying out some Harbeth speakers this weekend. Quite excited for that. I went to a few hi-fi shops around today and talked to them about this...have a few more things to try so I hope it is solved!!
Since the advent of small, high power, Class D solid state amplifiers and the rise in popularity of home theater, about 20 or more years ago, there have appeared in the market a myriad of small, self-powered subwoofers that typically also have adjustable crossovers and built-in attenuators (so the output can be balanced with that of the main speaker).  Try a pair with your present speakers, which in my opinion are probably excellent, as I have high regard for Focal.  What you are doing is shifting the "problem" (woofer dancing) from the main speakers to the subwoofers, which you can cross over to at very low frequencies, like 50 or 60 Hz.  The result will be a cleaner sound AND more extended bass.  Anyway, that's what I would do in your situation.  I wouldn't necessarily swap Focal for Harbeth, unless you are truly dissatisfied with the Focals for other unrelated reasons.
Neat. I was unaware that that's how they worked.  I'm not dissatisfied with them per sé, just a little underwhelmed in some cases.  A sub-woofer seems like it may be a viable solution though!  One of my potential upgrade paths are the 936s, simply because they have more range/volume.  Maybe a sub would be a viable alternative!
I'm just trying the Harbeths for fun (mostly)...they offered to let me borrow them so I said sure, why not? :)
What about other sources, such as a CD player? If the problem persists with other sources, its likely to be an amplifier problem.
Little pieces of this puzzle keep coming in. I can’t afford and don’t have the equipment to drive a subwoofer...but would a more full range (i.e. floor standing) speaker be a better choice when I do decide to upgrade next?


When the subject is cost-effectiveness then:

Skip the filter, waste of money, won't improve the sound in the least. The clamp will, but only if you get a good one. 

Always in my experience the most cost effective upgrades are tweaks. By tweaks I mean attending to every single facet and component of the whole entire system. Things like Orange fuse, Cable Elevators, HFT, ECT, PHT will bring improvement far beyond anything you can get for the same money the usual way.

You could for example replace fuses in three components with SR Orange, add Cable Elevators, and a full compliment of HFT, ECT and PHT all for about $2k and no way no how will you ever find any turntable or cartridge or anything else for $2k that will come anywhere close. 

Then factor in that these are all "lifetime" in that they will all work wherever you go and whatever you buy forever. Its no contest. Nothing else even comes close.

Also power cords, interconnects, speaker cables, Cones, and Shelf. Same thing. You simply cannot find any component anywhere for say $500 more money that will do what a $500 power cord (or interconnect) (or speaker cable) will do for what you already have. Well, from Synergistic, I should hasten to add. Not that there aren't others this won't work with. I just happen to have 30 years experience that tells me with SR you can throw a dart. Everyone else you pays your money....

Note: not idle speculation- I have TRIED! Compared. Home auditioned. Put a $300 Synergistic Master Coupler on a phono stage, you won't get another phono stage that good (without the pc) until you're into it for three to five times as much. If even then.

My system is heavily tweaked out with all this and more. I've done demo's and removing even one or two of these people notice right away. Heaven forbid I should remove it all, let you hear what the same components sound like the way most people do. Shudder. Cue Brando: "The horror... the horror..."


@millercarbon I see what you're saying, but I don't *think* that my base system is at a level (at the current moment) to benefit from such tweaks, save for the stand and cones.  The whole thing is worth about $4000.
Is it consistent with all records or worse on some than others? If its the same it could be a bad or dry platter bearing. Check the bearing and see if it needs lube or if there is play in it. Also check to make sure the TT is perfectly level, measured on the platter. Its also good to have a test record to check the performance and setup of the table. Spend some time checking the table for proper setup (or have a dealer help you). Its the only way to get the most out of what you already have. Some how very low frequency info is entering the system and a bad bearing is one posible cause. Better quality TT’s have better bearings. Good luck!
@sonicjoy I've just finished doing some more experimenting...and I think that after alllllll of this, it is just record dependent.  I'm relieved, but not overly happy that it's something so simple!  My Hotel California LP must be particularly bad, especially the way I was playing it with loudness on.  I found that if I moved to certain records and cranked it (with loudness off of course), there was very little/no woofer pumping.  I still would like to try a filter to get rid of it, just for peace of mind...but now I'm not so worried.

It was set up by my dealer, so I'm not worried about that.  They're experienced.  I do intend to get a test record one day though.
KAB rumble filter will take care of all your problems with no side effects. Call me a very satisfied customer. 
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"My Hotel California LP must be particularly bad, especially the way I was playing it with loudness on. I found that if I moved to certain records and cranked it (with loudness off of course), there was very little/no woofer pumping."

The loudness control should only be used at low listening levels. It’s no wonder that the woofers are pumping like they are. If you use the loudness control you are wasting your money with any kind of rumble filter!
The fact that a subsonic filter eliminates the woofer pumping indicates that there is an isolation/feedback issue of some sort. Figuring out the sort is the trick. The problem may not be acoustical.

Your cartridge is picking up some low frequency vibrations form somewhere and creating sometype of feedback loop within in itself. A subsonic filter does not eliminate the problem it just keeps the problem from being amplified and sent to your speakers.

Is it possible that there is some electro magnetic interference being created by something not system related or possibly in your power grid that could be causing the problem? Have you tried a power conditioner?

Where's Ralph and Almarg when you need them?
The OP did not try a subsonic filter. He is using the loudness control that is causing excessive woofer pumping. That is what seems to be the problem!
@audiorusty You're more than likely right about it being some sort of power related problem (to an extent)...but I think what's causing most of what I'm experiencing is just certain uneven albums, with a little too much bass from my settings

@yogiboy I did try a subsonic filter, it fixed it, but it's not mine so will be getting my own soon.
I would expect woofer issues if you use the loudness function!
The more you turn down the loudness, the more it boosts the bass. It does not roll out until you are halfway across the dial on most volume controls.
I prefer not having the loudness on; in reality there is only one **sound pressure** at which the loudness setting could possibly correct, sort of like a clock that doesn't work is right 2 times a day. So its highly likely that all its doing is introducing coloration!
BTW, a ported loudspeaker that only goes to 55 Hz isn't going to have its woofer properly loaded at frequencies below that. Its very natural for it to pump around as a result. A sealed box would be less prone to this issue.

Millercarbon, I don’t say that I’m right and you’re wrong, but I am at opposites to you with respect to all the SR products you mention in your first paragraph or two on tweaks. Not that those things can’t make an audible difference, but I cannot imagine a more profligate way to spend money for what could be very tiny results.And none of those items will address the complaint that brought the OP to this forum.
I've done some critical listening and found that unless my speakers are above a whisper, the loudness kind of makes them muddy anyway.  If I play a smoother record (especially in the inner tracks), the woofer pumping is not there, even at high volumes (loudness off).
I guess the issue is solved! Thanks to all.
That is what subsonic filters on amplifiers used to be for, I think.
I had a very similar issue occurring at higher volumes and and only at the beginning of the track as soon as the needle dropped (before the music played) - the woofer seemed normal once the track started playing. Brand new Stabi R - so it bugged the crap out of me. After much fidgeting, I narrowed it down to my Google Wifi router which was in proximity to the turntable. After moving the Google Wifi to a lower platform on my rack, most of the issue seemed to go away. Loudness on my ARC Ref 2SE is on - there's no other way to listen to it. Any chance you have a router nearby?

Currently, the acoustic feedback (that's what I'm calling it) is 95% better.  HRS suggested that I try replacing the regular feet on my platform with low frequency feet. I just got them today - I'm hoping they'll work.
@rdk777 Very interesting...I think I've removed everything from the proximity of the TT that may cause that.  Someone told me it could be a dimmer switch on the same circuit.  Turned out to not be that.
Just looked up your ARC Ref 2SE, that's one hell of a phono stage!


I had the same problem. I have a Rega 3 TT with Exact cartridge like you I tried everything but nothing worked. I even added two subs to my system. I broke down and got the KAB filter and problem solved. I’ve listen with and without the filter and there is no loss of sound quality. Well worth the money. 
You need a subsonic filter. In the past many phono stages had them built in with no bypass switch. No idea why they have become optional. 

The pumping is the vertical movements of the cartridge being translated into low freq audio and then being massively boosted by the RIAA Eq. You have a fairly light arm and a high compliance cartridge so it's unlikely to be a cartridge/ arm mismatch. 

If you added speakers with more bass response the pumping would not change. 
I had a similar issue with a Pink Triangle turntable using a Moerch tonearm and a Benz Glider. It turned out that my TT was just too close to my speakers. I changed my system layout and the problem disappeared. Good Luck sorting this out.
@lenmc2964 It seems to have settled down a lot dependent on the record I choose, and my bass settings, but I will still likely consider the rumble filter in the future :)
@raindance I have no idea either, it should really be a no brainer to include IMHO.
@joey54 thanks!