Dustcover Blues

Partial retraction.  OK, I see that if it were the movement of air in the room, caused by your woofers, that was inducing the Helmholtz effect, then shutting down the woofers would possibly reduce the SPLs sufficiently to ameliorate the Helmholtz resonance of your dust cover/TT.  I guess I just find it hard to believe that your subwoofers blow around enough air to do that, but I have not been there, as you have.  Still, I would take a look at your room frequency response correction devices at the suspect frequencies.

Your microphone test for proving the utility of a dust cover.  Isn't that highly dependent upon the room, the speakers, and the proximity of the TT to the speaker?  In other words, you could prove it for yourself and your system, but not universally for all situations. I'd move my turntables before employing a dust cover to shield the tonearm/cartridge from SPLs.  In addition, what do we know about the importance of the effect you observe, in terms of ultimate fidelity?

Dear @mijostyn : I don't know which kind of material you are using in the dust cover.  Years ago when I was using two Denon TTs 80/75 each one was mounted in an Onyx 50kg base and the other marble of more or less same kgs. and I was using with dust covers made it of tigthness glass really thick and I can't remember any trouble down there. Dust cover material is critical.

I don't use any more.

R.

R.

@mijostyn  : At some time we should just seat and enjoy the MUSIC in each one room/audio system.

That " time " is different for all of us and I can see that it's not yet your time. You are still looking for the best way to arrive at the top quality level in your system.

All of us live years and years of room/system up-dates/up-grades/tweaks and the like.

Today my "time " let me enjoy more and more listening MUSIC hours and I think that my " time " is arriving to its end. Can I be sure about? well more or less.

What am I  doing on my system this weekend? something that's a necessity but not really and up-date or tweack job: my Levinson 20.6 Reference monoblocks amplifiers have around 33 years that were made and these running pure class A design over those years work with no single fault but the power supply filter capacitors  I think " needs " to be changed and that's what I'm doing. The cap´s already arrives from Mouser: Vyshay_Sprega and that's it.

Sooner or latter you will done on your room system with out missing the " fun " of those years of up-dates.

R.

I have custom acrylic dustcovers for my 2 turntables(that are on Townshend platforms) to cover when not playing.

While I wouldn't mind, I thought it wasn't a good idea to use them during playing. 

There's one way to use a dustcover when playing that will actually work in terms of both dust and vibration control.