Why are my woofers pumping?
The other day, with sunlight direct from the side, I noticed that the
woofers in my speakers are pumping in and out, much more than I was aware of,
when the stylus is in the groove, even between tracks (no music). I can see it, even if I don’t hear it. Why
does it happen? The woofers behave normally (no pumping) with digital music, and
when the stylus it lifted from the groove, so it is not the speakers, amps,
preamp or phono stage.
I’ve read that the typical reason for woofer pumping is that the cartridge / arm resonance is too low. I tested, with my Hifi News test record, and yes, the lateral test puts the resonance at 7 hz or so – too low (but I’ve seen some doubts about the results from that test record). It is strange, since the combo I use – Lyra Atlas cartridge and SME V arm (on a Hanss T-30 player) is supposed to work well. I tried to strip my arm of extras, cleaned the damping trough, etc – but it did not help much.
Anyone has an idea, why it happens, or what to do about it?
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- 185 posts total
@o_holter : Again: https://forum.audiogon.com/discussions/why-are-my-woofers-pumping/post?postid=1551771#1551771 With all respect to those gentlemans that insist on the KAB filter or the like please ask you: who of them owns the Atlas or even listen that kind of very high quality performance levels? Seems to me that no one of them because they are not taking in count what really means: quality level performance at the Atlas levels- They say that with the filter they almost did not listen degradation and this just makes no sense. R. |
Almarg 4-24-2018 Consider replacing the belts! Best regards, -- Al |
Correction: the Atlas has a 121 ohm load (not 100) - and sounds fine. Replacing belts - yes, new ones ordered. I will give the spindle a drop of oil, and fasten the spindle housing when I get the right tool. BTW, reading up on the Hifi News test record shows that people find a lot of problems with it. On the lateral resonance test the actual test tones are different from those stated. I know from before that the record's anti-skating test is not good, in my case at least. Some years ago Michael Fremer reviewed the Kuzma 4-point with his Lyra Titan i cartridge, pronouncing it the best arm he had heard so far. But using the calculators, resonance is down to ca 7.2 hz. Even more problematic than with the SME V (ca 7.5), since the 4-point weighs a bit more. Yet it wasn't a problem, to his ears. |
Hi Raul, thanks, I reread your former post, where you wrote: "even at 100hz the Atlat compliance and effective mass puts the resonat frequency in a " solid " 8hz." I get results closer to 7hz (arm mass 10.5, screws 0.5, cart 11.6g). It all depends on what we assume is the 10hz measured compliance (supposed to be x 1.5 to x 2 of the 100hz measure - 12 in the Atlas case). I have to assume a compliance of 17 to get above 8hz. I have found no exact Lyra specification. So this is really "blind", especially if we assume - as some do - that small variations in resonant frequency play a role, at the margins at least. I get confused by all the web debate on this, "fundamentalists" who say resonance is of key importance, some who say it varies with the type of arm, player, and what not, and some who simply dont believe in it (at least not with modern fairly "medium" cart/arm combos). Likewise, I can find no objective measure of how much the resonance increases, by adjusting the static counterweight so it does all the lifting on the SME V, compared to using the dynamic spring mechanism (but a lot of debate about how the dynamic may sound best and be more kind to the cartridge). I do see the point of Lyra including light weight alu screws (among several types). Regardless of their problems, both the Hifi record test and the calculators indicate that the arm could be lighter. So - back to the ears? Only listening can really be the judge? Test records not correct, calculators failing to take into account important parameters - like the arm stiffness - you name it. |
- 185 posts total