Tube Phonostage Causing Rumble and Noises

i had not a rumble, but a low, loud, buzz (or hum!? No clue what he right term is) that would gradually appear (especially listening to “sticky fingers” Riling Stones) if my volume was too high using the turntable. It wasn’t coming off up the turntable, either. This is a super-isolated VPI Avenger Titan, siting on a 3 inch slab of hardwood with rubber feet, sitting on a Symbol Audio table.

i read somewhere that the cause could literally be sound vibrating the stylus or cartridge.

I had extra GIK bass trap panels and lined one up right behind the audio cabinet, just sitting on the floor with about two feet sticking up so it absorbed the “bounce” off the back wall. Immediately went away.

i then did a cleaner install.

@davetheoilguy I recently started playing with VPI turntables, and really love them BUT they are more susceptible to a ~ 100Hz resonance, in my experience. I first perceived this as a background rumble / hum / buzz which became more pervasive with higher playback SPL, and thought it was a ground loop - but upon further investigation, confirmed it was indeed feedback!

It’s a combination of the plinth and tonearm. I’ve experienced it with Aries 3 and Avenger Reference, on a Critical Mass Systems rack and Platinum filter. In my case, the issue got FAR worse with the 10" 3D arm wand. With the Fatboys (both uni and gimbal) the problem is mitigated enough to no longer be a concern. The 10.5i metal arm is actually quietest of all (its problem resonance is much higher in frequency but also much lower in level), though the Fatboys do sound better overall. The original 3D arm was just unusable in my small room. In fact, at a high enough volume it could be triggered into runaway feedback - fortunately I’m quick on the mute button! You could destroy your speakers otherwise.

I’ve read a couple other instances of this issue with the original 3D arm, but it doesn’t seem to be well known overall.

With my Clearaudio magnetic bearing (CMB) decks, there are no problems with 100Hz (drum beat like) frequencies, but they can be hell at subsonic frequencies (visible woofer flapping), unless you have truly excellent support underneath them.

Again, I don't think any kind of table feedback is OP's issue since he says it happens with needle out of groove. The cartridge coils form part the "constrained" layer between vinyl groove / cantilever on one side, and damper / suspension on the other side. When stylus is lifted out of groove, it cannot generate signal. 

Thanks everyone for your feedback and advices. I think I will take the easy way out, ie play records without the sub.

Thanks a million.

@mulveling 

“With the Fatboys (both uni and gimbal) the problem is mitigated enough to no longer be a concern.”

Sadly, this is also the Fat Boy — Kevlar 3D printed.

I also have the Esoteric Grandioso turntable.  Same issue when I used the Van den Hul Frog Gold cartridge, so I think it’s the cartridge, which is otherwise lovely.
 

I two huge SVS PB 16 ultras and Bowers 800 (Diamond) to fill a big space and I like to listen loud.

I measured and had an off the charts standing wave peak about 1.5 feet off the front wall.

Regardless of what is picking up the feedback, the base trap solved the issue.

@davetheoilguy 

Interesting - still so many surprises and lessons to be had in this hobby! That's cool you were able to isolate the problem to standing waves, and resolve with acoustic treatments. I *think* the majority of my issue here was structure-borne energy, so that is indeed different (moved rack around a lot trying to avoid the worst of standing waves and structure-borne energy). I've recently had the Frog Gold on the Fatboy here. And agree - it's such a lovely, well balanced cartridge!

@mulveling 

I’d love to say I’m an acoustic genius, but I figured out it was a standing wave because every time I went to look at the turntable to figure out what was going on, the sound would rapidly fade (and my heart would start beating way too fast, which I figured out was relevant later).

A very Heisenberg’s cat situation.  I’d look and the sound would go away.

Eventually it dawned on me that my body was breaking up the wave.  Did a little trial and error and then tests to confirm.

The weird heart rate is a classic symptom of intense subsonics, which I knew from working in a haunted house when I was a teenager.