Low frequency rumble

AdamG wrote: Hello from a new member I've just replaced a my pre & power amp with a new integrated and GSP Communicator phono stage and am getting woofer pumping that hadn't occurred previously. The driver movement is cyclic, greater on the outside tracks where cantilever travel is greater compared to inside tracks, and relative to volume (obvious even just above low volume but increases with volume). It doesn't seem to be causing any obvious erroneous though. I understand this to be low frequency rumble. Nothings changed with the TT which is Technics 1200 with ATM 440MLA. Am I right in attributing the rumble to the change in phono stage or could there be another cause. Thanks Adam

I'd have said it's warps. Even with the flattest records there's sufficient energy when you consider the tiniest stylus excursion can result in thundering bass. I've never noticed rumble to such an extent with a Technics SL1200.

Some phono stages use sharp filtering of subsonics but this can send the bass too far out of phase. However, during extreme cone excursions, at the extremes of travel you can run out of movement for higher bass frequencies. But let's not panic - if you observe some "tighter" cones (especially in professional situations), they hardly seem to move whilst producing some powerful bass. Unless you're getting bass clipping (a scratchy noise on extreme bass) there should be no need for concern.

Edit: If I thought users speakers were at risk I wouldn't have been making commercial phono stages this way for more than 12 years. Speakers are more at risk from DC offset and being driven into clipping by weak amplifiers. I consider our £1,476 Harbeth M20 mini monitors safe with this amount of cone excursion on warps.


Edited by Graham Slee - 19 Mar 2012 at 9:07am

Fatmangolf wrote:   Adam can you feel or hear anything between tracks, please?

Still trying different albums (not much time at the moment) but of the 6 or more I've played all are producing equal pumping more pronounced on outer tracks.

The last one at least was causing pumping between tracks. No noise between tracks and hard to comment on any SQ issues during but nothing obvious.

I am starting to understand the inherent rumble of vinyl recording but the driver excursion I'm seeing on outer tracks is significant (have to say near ~75%) at moderate volume.

It's difficult for me to gauge how severe the pumping is as I haven't seen this on anyone else's set-up or with my previous NAD1155 pre.

FYI my amps 55W high current.

Just throwing this out for consideration, when you installed the cartridge, did you "zero balance" the arm and reset the VTF scale to 0 before applying the appropriate amount of VTF ?

Apologies if I am labouring the obvious here, but it is a necessary step prior to any further adjustment to the setup to reduce the severity of the issue without compromising desirable response.

tg wrote: Just throwing this out for consideration, when you installed the cartridge, did you "zero balance" the arm and reset the VTF scale to 0 before applying the appropriate amount of VTF ?

Welcome all possibilities tg. The cart was set up properly when fitted but I haven't revisited for some time.

I'm using 1.6 g VTF which from memory is at low end of manufacturer recommendations.

Reseting VTF and even trying another cart was one of my next tests.

Adam