Why are my woofers pumping?

Thanks, all! I think we can conclude that

1) the Atlas / SME V combo is very “receptive” in the lowest frequencies, and that in some resolving systems this may give unwanted effects like woofer pumping.

2) this is mainly a resonance problem, not a rumble or player noise problem (it does not change much, with different platter mats, damping or stabilizing the turntable, etc), and the first measure is to try to move the resonant frequency up - reduce the effective mass of the arm. This is only slightly possible on the SME V, but even small changes may help

3) the somewhat "over-eager" reception at the lowest frequencies of the Lyra/SME combo makes it even more important to correct any residual system noise, drive noise or rumble.

4) if the problem persists, try a rumble filter.

I will now try to decrease system noise – check the turntable, bearing, oil, feet, etc.

I wonder, even if the pumping is already reduced, would a filter be an idea anyway? Are my woofers straining too much, in the lowest bass? Is this prone to happen more, when the suspension of the cartridge is more worn?

@o_holter - You mentioned earlier in the thread about an XLR filter. I was struggling with the same woofer pumping problem and finally commissioned Dan Satoni at DTS electronics to build a custom balanced high pass filter for me. Problem solved with no obvious loss of sonic performance. I know Dan has a minimum board order of 5 units so I am pretty sure he can quickly build another one for you if interested. It wasn't exactly cheap ($550 CAD) but I feel it was an exceptional value at that price.

Todd

VPI Classic 3 w/Lyra Delos -> Whest PS.RDT30 SE -> Custom Filter -> ARC Ref2 MkII -> ARC VT100 MkIII -> Magico S1

Please note that woofer pumping is not only caused by the cartridge/arm. Some CD's cause pumping as well. Hopefully you have a "low-cut" option. Use it only when needed.

Han_n - yes I will test this more. The "low cut" option may be what I lack.
Toddc2 - thanks, I have followed up.

I mailed an audio tech the other day, is it likely my woofers are getting worn out? Even if I don't hear clear problems? Answer: after five years no - it is not likely.

Some more pumping and woofer cone vibration testing today.

Pattern confirmed: the misbehaviour is less than before, but still noticeable on very high volume. There is some subsonic pumping (I can see it but not hear it).

The interesting thing is: it happens at certain intervals per revolution of the record (playing silent grooves between tracks). If I turn up speed to 45, the pattern is repeated, only faster. This seems to indicate that player rumble or drive problems are NOT the main issue. The platter on the Hanss T-30 is perfectly levelled and revolves smoothly – the pitch is steady, there is no sign of imbalance or distress, and almost no perceptible vibration noise touching or stetoscoping the plinth.

So if the player is mainly fine, the answer must be that the cart/arm combo picks up “vinyl noise”. Please correct me if I am wrong!

Could this “inherent vinyl noise” be most strong down around the resonance frequency, at ca 7 herz?

I am investigating different filter options, with helpful answers from KAB and Satoni, thanks to your advice. Since I have invested in a balanced system (from the phono stage to the amps) I am not so keen to go back to single ended connections from the phono to the preamp, although this would be the easiest (and cheapest) way to know if I am on the right course – if a rumble filter would help.  

o_holter

Some more pumping and woofer cone vibration testing today ... still noticeable on very high volume. There is some subsonic pumping ... it happens at certain intervals per revolution of the record (playing silent grooves between tracks). If I turn up speed to 45, the pattern is repeated, only faster. This seems to indicate that player rumble or drive problems are NOT the main issue.

That actually sounds very much like a drive problem, such as a bearing issue or bad belt

.... Could this “inherent vinyl noise” be most strong down around the resonance frequency, at ca 7 herz?

I don't think what you're experiencing is “inherent vinyl noise.” I agree with @stringreen - it would be a good idea to start at square one and have Lyra check that cartridge. Did you buy it used? If so, it's immediately suspect, even if it isn't your only problem.