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Subwoofer rumble issue

I’m having a hard time solving a problem that seems to come and go. My subwoofer will rumble uncontrollably when playing records at a higher volume. If I turn the volume down sharply it goes away but when I creep the volume back up it comes back. I’ve tried isolating my turntable as much as possible with diy books, isolation feet, etc. (I don’t want to buy an expensive isolation platform unless that really is the issue.) Any thoughts on what I can do to fix this? Thx!
paulgardner
georgehifi's avatar
georgehifi
10,312 posts
 
Back in the TT days Paul you had speakers that were lucky to go below -3db@50hz, now there’s subs that can go 2 octaves lower, with 1000w plate amps, this is what I found with Linn LP12/Ittok/Supex1000 and my Kef B1814’s 19hz, then CD came along, and then no problems.

Cheers George
paulgardner OP
183 posts
 
Well I’m not going to CD
georgehifi's avatar
georgehifi
10,312 posts
 

No not telling you to, would never do that Paul, but beside putting the TT in another room, it was the only other fix for me with bass that goes to very low frequencies.

Just dawn on me, if you have any tubes in the chain, these can go "microphonic" some call it "euphonic" (w**k w**k) and this can cause runway bass oscillation also.
If you have then do the finger nail light tap test on these just like the plinth test, but without the stylus on the record this time.

Cheers George
paulgardner OP
183 posts
 
Ok I’ll try that test and report back. Thx
big_katydid
50 posts
 
years ago I lost a bass unit on a rega jura. The combination of TT, room, track and record warps led to a loop that saw the drivers very quickly oscillate more and more until the paper cone literally tore open around the center area, this took less time than I could get over and turn the volume down....the other driver survived the experience, I don’t think the voice coil burnt out but somehow the extreme excursion caused the cone to rip.
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