52 responses Add your response
Check phase: you mean speaker phase? This is correct.
DC at amp output: can you explain this?
I probably should have mentioned that I'm using a Triplanar/Dynavector XV-1s.
Read up on the rumble and it does describe my situation. How normal is this? Is there something that can be done or does one just live with it?
The cause of this problem is most likely very simple. Is the woofer pumping worse at the beginning of the record and then lessens as the tonearm moves toward the center of the LP. If so, the outer edge of the LP is probably not coupling with your platter. You may even be able to see light between the outer edge of the record and the platter when viewed on-plane from the front.
If you are using a clamp, try lessening the downward clamping pressure to see if that helps. If it is a problem with LP/Platter coupling, the best solution is a peripheral ring (like the one sold by TTweights and others), but some say that these rings deaden the sound as well. I don't have one so I don't personally know about that.
If the pumping occurs across the entire LP, then Cpk likely has indentified the cause(s) above.
Madfloyd, you system thread lists TW Acustic Raven One as your turntable.
If that's the table playing and your woofers are pumping it's not due to rumble. The Raven is a quiet turntable with very low rumble but it could be susceptible to mechanical feedback which causes low frequency pumping you describe.
Many turntables are sensitive to vibration from footfalls or speaker bass output. How was your Raven set up, a professional familiar with the product? What kind of stand is it resting on, and is your floor completely solid or perhaps pier and beam (suspended).
I may be way off on this, but if your woofers are moving like crazy, you should be able to hear it. If you are not hearing the bass, maybe your listening position is in a null. I have measured a 10db difference in bass by moving my listening position back 1.5 ft.
Is it possible for a woofer to be moving like mad, but not being able to hear the "subsonic" frequencies they are creating? My woofers are behind cloth at the back of the speakers so I can't see them.
you are experiencing a very typical phenomenon as Vegasears suggests. Only a filter that eliminates those lower frequencies will eliminate this. I would venture to say that the other possible causes mentioned may play a diminuative role also. Seek out an inexpensive filter online and try it out for you to see. Then, after concluding that this may be the case, you can start getting the typical audiophile paranoia of whether this is now altering the overall signature of the music.
Thanks for all your replies. I do think it's worse at the beginning of an LP.
My floor is concrete, but the turntable is at the back of the room where there is bass buildup. I think my stand is fairly solid, and I'm using a Terrastone platform underneath my turntable. Coincidentally, I just received this yesterday - it replaced a wooden shelf. I can tap on the terrastone shelf fairly hard and there is (seemingly) no effect on the turntable. I had the rumble issue before changing the shelf.
Dlcockrum, I have the TTWeights peripheral ring, I'll try that and see what happens.
I have to imagine this is adversely affecting the sound of LP playback...
YEah, its rumble originating from the warp inherent in many records that is typically at highest magnitude at the beginning of the side/outer edge perhaps magnified by sonic feedback from vibrations.
A concrete floor is good. IS the table sitting on a solid foundation/stand upon the floor? If not, it should be. If it is sitting up high on a stand, try a lower platform perhaps?
If the table is sitting rock solid and you still have problems, a switchable subsonic fileter may be the only remedy, but if all else is well, then in most cases practically this is not needed.
If your woofers are moving with large excursions for reasons other than the signal from the record, then this is utilizing power to produce noise and the power is not then available for the actual signal/music.
BTW, some of this (woofer excursion due to rumble) is naturally inherent in record playback. If you have everything else set up well together and the records are not abnormally warped, then I would not worry about it.
Not familiar with your table, but another thing that can help is to have a tt platter that is large enough in diameter to support the record all the way to the outer rim properly. TAbles with smaller platters are generally more susceptible to this particular curse.
Also, if you have a dustcover, keep it down while playing. THat should help minimize the unwanted effect.
mapman, I experienced the same problem a while back and purchased rumble filters. It took care of some of the problem but not all. In my paticular case a change of cartridge did the trick- no rumble woofer movement now. I know this is not what you want to hear and may not be your issue but it is what it is. I will offer to let you try my filters to see if they work for you if you like- no charge of coarse. PM me with your address if you want to try them.
YEs, changing cartridges may have an effect but I am not certain how to determine what to switch to to assure desired results. Higher compliance maybe? Something that produces a different resonant frequency with the specific tonearm utilized perhaps?
PErsonally, I am not a fan of filters of any type. With proper setup and match of equipment, the problem is usually not an audible issue to start with. GEtting to that is the trick of course though. Record players can be tricky beasts and not easy to get right!
One thing you might try is to put a gram or two of something like blu-tack on your headshell and a corresponding amount on the counterweight so that your VTF remains the same.
This will change the effective mass of your arm and the resonate frequency of the arm cartridge.
It may or may not work but it is cheap and simple to try.
I am considering buying a TTweights peripheral ring, so I would greatly appreciate your feedback on whether it reduced/eliminates the woofer pumping and also you perception on its effect on sound quality.
Although the woofer pumping generates frequencies that are (mostly) too low to hear directly (unless the woofers are bottoming out), it does load your room with low frequency pressure that will affect the sound (ala REL sub, but in an uncontrolled way).
I have some records that are worse than others when rumble is observed via cone excursion. Same cartridge. Concrete floor...shelves made with carbon fiber/epoxy 1/2 inch thick. The Navy uses this material on bulkheads to minimize internal shrapnel from external explosions. No clamp or other weighted object reduce rumble in my case. Probably in most cases.
Clcockrum: The ring I have is fairly light and isn't much help with most warped LPs. I used to own a VPI table and their peripheral ring worked wonders for warped records.
The TTWeights ring does nothing for my rumble problem, but if I recall there were more than 1 option of rings at TTWeights and I think I got the lightest one.
Well so far I've reversed phase, add damping fluid to my Triplanar arm, double checked level, tried raising lowering VTA, all to no avail.
Kevin at KAB suggested that his filter would be a bandaid and that damping should be the real solution, but unfortunately that didn't work.
Apart from trying a filter, I'm left with the notion of replacing the table, arm and/or cartridge, all very painful thoughts. :-(
Agree with Vandermeulen and others. Don't change your table, tonearm or cartridge. There's almost no chance that would reduce woofer pumping.
I find Kevin's suggestion regarding damping fluid rather odd. Perhaps it would help on one of his tonearms, I don't know them, but it wouldn't on a TriPlanar, at least IME.
Did you experience less woofer pumping when you had the Doshi preamp in your system (if you remember)? Compared to our c-j, the Alaap reduced WP a lot. Nick doesn't include a rumble filter per se, but his circuit is designed to roll off around 16 Hz or so IIRC, which helps.
Thanks, Doug. I did remove the damping fluid as I didn't like what it did to the sound (I've now removed the damping trough as well).
I wish I knew whether the Doshi worked better in this regard, but it was only recently that I removed the lower grills; I have no idea how long this has been going on.
I did try an old Project Tube Box SE II phono stage that I still have - it has a subsonic filter (18hz with 24db slope) and that worked (not that I would use it as my phono stage).
So, this wasn't an issue until the woofers were "seen" doing the dance. I don't think there was much mentioned about "hearing" any issues. Certainly finite detail at low freq. might be improved by defeating the woofer dance, but it usually comes at the cost (price and performance) of additional components in the case of using sub-sonic filtering.
The issue that most miss can arise IF there is not enough headroom in the amp to prevent clipping when those cones are moving an inch in both directions.
I don't know the circuit details (probably wouldn't understand them if I did) but Mapman's comment seems about right from what I remember Nick saying. It's certainly not switchable. I got the impression there's no active filter *added* to the circuit, but rather its a characteristic of the circuit itself. Sorry to sound so mystical about it.
Agree with Dan_Ed, with some elaboration. Certainly if the amp stage or its power supplies clip due to the extra LF energy you'll have sonic problems.
More subtly but more commonly, if the amp or its power supplies are easily modulated by the extra LF energy then it will congest on complex or dynamic passages. Dan's amp and mine (more Doshi stuff, sigh!) are about the best we've heard in their power class for the ability to resist such congestion. The power supplies are radically overbuilt and very carefully grounded, which reduces signal modulation of the PS to very low levels. Similar class amps played side by side are often less transparent, and I'd expect those amps would suffer more from woofer pumping.
If the amp has sufficient isolation and headroom then I agree the sonic effects would be lessened.
The Wikipedia seems to indicate that rumble affects the sound even when not audible.
"Even when not audible, rumble can cause intermodulation, modulating the amplitude of other frequencies. The unweighted response curve is intended for use in assessing the level of inaudible rumble with such intermodulation in mind"
Also, one has to wonder how a speaker can produce accurate bass when the woofers are pumping violently.
That being said, I've given up on doing anything about it for the time being.
Definitely, you are reproducing the record warps. You need a subsonic filter. Your amps are using a lot of power to reproduce frequencies that you cannot hear, and that you don't WANT to hear. Also, if you are using a heavy arm with a high-compliance cartridge, this makes the problem even worse.
Tell us what cartridge and arm you are using together.
Oh, I just found your answer. The Triplanar/Dynavector XV-1s is a fine combination. So you simply have warped records and a system that reproduces 3 to 10 HZ very accurately. You need to insert a subsonic filer.
Sounds that you can hear, you cannot see. If you see your woofers moving, it means you are reproducing frequencies that should be filtered out.
Very likely it is simply a matter of ported speakers and the sound is lower frequency than the port tuning frequency on the speakers.
When you have sounds below the tuned port frequecny of your speakers then the woofers flap around uncontrollably and make almost no sound, which is exactly what you have. Sadly, this flapping around will add plenty of IMD distortion to any music you play becuase the speaker drivers are operating way way outside their linear range when they pop out of the speaker in the way you have observed - look for a big port on your speaker probably tuned around 30 Hz to maximize bass extension...
Either you can filter out all the LF electronically or select a different design of speaker...
Yes, ported speakers are more commonly susceptible to this kind of thing from what I have observed over the years, but I think the problem can affect other designs using dynamic drivers as well.
I think since porting is a very common approach to extend low end response on speakers that the problem is more common there, but not a result of the porting itself.
Not sure about IMD distortion, but it still might result in faster amp clipping even with a planar or electrostatic speaker with similar frequency response I would think.
I'd suggest the KAB rumble filter. I had the same problem, and not only it most likely affects the sound adversely, but it might also with time damage the speakers' voice coils since the woofers expand uncontrollably.
At first I thought I noticed a slight difference in sound upon installation of the filter (slight lessening in bloom or thickness perhaps), but now I think the sound is tighter and more detailed. All in all, when you weigh the pros and cons, I'd go with the filter before doing anything else as you have not much to lose but you could possibly benefit significantly. You have a world-class set up; I think you can spend another $160 to possibly get the best out of it.
Wow, this two year old thread is what I am experiencing right now
I also have woofer pumping to a great degree
Triplaner arm, zyx cartridge
I have records which don't appear warped but have slight air gaps between the record and the platter as the table spins (coupling issues?)
I also have a Doshi preamp which rolls off at a very low freq. There is the option to change out the capacitors on the phono pre although Nick feels it affects slightly higher freqencies.
Mine isn't positioning - passed the placed the needle on the non spinning record test.
Placed a nickel on the headshell and couldn't tame arm / cartridge resonance.
May try a TT periphery clap, but not sure it would fit in between my platter and triplaner. Also the risk of breaking a Universe may be too much to try.
My Salk Soundscape 10s go down to 22 hz at 1.5 dB down. Is there really usable music down there outside of Saint Saens Organ Symphony #3 ( not HT )?
Seems to be robbing a bit of my amp power left for musical dynamics
The cartridge and arm are known to work very well together.
Starting to lean towards rolling the doshi off higher.
Any other suggestions?
Yes - a rumble filter I recommended in the last post before you revived the thread. At this level of playback and setup, if you're still experiencing woofer pumping, I'm not sure what else you can explore to address it. Perhaps moving your turntable from between the speakers if the room allows it, but I'd suggest trying the KAB, which I found very transparent and incredibly effective.
You might play with the way your counterbalance is set up. The Triplanar has a multiple weight system and you can use that to affect the effective mass of the arm and cartridge.
If the effective mass is off, the setup might be susceptible to warp and the like. I have the same arm and cartridge, with no problems and no rumble filter.
We have the large weight and one of the smaller ones (about 3/8" thick) set fairly close together to get our tracking pressure. The amps and preamp have bandwidth to 2Hz no problem, but no problem with woofer pumping either, even with some pretty warped records.