[BobM]

Jim, on some records (not all, but perhaps 1 in 10) I have a problem with subsonic frequencies sending my subwoofer into perturbed rumblings. I just turn it off now and the rumblings are reduced, but sometimes it is still slightly audible through my regular speakers.

I have been considering implementing a subsonic filter of some sort that is easily switchable/bypassable on/off so that it is only in circuit when I deem it is needed. How would you suggest doing this either inside the Trumpet or exernally, between Trumpet and preamp?

I don't see many separate products offered to address this issue, and the one's I do see I am not keen on, since they are not switchable and not adjustable. I would ideally like something flat to 20Hz and -3db down by 15-17Hz or thereabouts.

Any thoughts?

Thanks,
Bob

[hagtech]

Yeah, I made the TRUMPET reach real low, so that there would be very little phase shift down to 20Hz.  However, that means you need one very good and expensive turntable. 

There are two ways to address this.  Modify the TRUMPET circuit to move the high-pass, or add another one externally.  Ideally, if your turntable can't handle the subsonics, then you could change the 220nF (4 of them) between 1st and 2nd gain stages to something smaller, perhaps 100nF or 47nF.  Doing such voids your warranty.

jh

[BobM]

Thanks Jim. I guess I'll try adding a little more silicone damping to the arm first and see how that improves things.

Like I said, it doesn't happen on all records, just a few, but when it does my inner ears are really thumping from the extremely low non musical frequencies filling the room.

Bob