VPI Prime Sig/Lyra Delos / Feedback ...help!

Yeah, I've fought with that on VPI tables in my "difficult room" office setup. Went though all the usual "maybe it's the cartridge / phono / etc" and tried several combinations of each. I've even used 2 different VPI tables here: Aries 3, Avenger Ref. These VPI tables and their arms do seem to pick up frequencies around 100 Hz plus/minus. The Clearaudio Innovation Compact I used prior to these didn't have any problem in these frequency ranges, but then was a nightmare in the subsonic frequencies - which are potentially dangerous to your speakers. 

If your rack / shelf / feet aren't isolating enough at these frequencies, you'll have a problem. Feet can help a little - the HW40 feet seem to mitigate it by ~ 6dB? The classic Signature feet were absolutely useless. The shelf you have the table on matters a lot. I have a Critical Mass Platinum on a Sotto Voce (very expensive) that's surprisingly ineffective at these frequencies - in fact I think it's contributing to the problem (I place more blame on the rack structure underneath). I've heard from a friend that Symposium Ultra platforms was effective for him. I think a Townshend Seismic platform would probably clean it all up, but they're awkward to use and I sold mine with the Clearaudio. 

The one really surprising finding I've made in all this - the VPI arms with 3D material pick up this feedback a LOT more readily than the older metal arms. Even unipivot vs. gimbal vs dual vs fatboy (they're all 3D material) doesn't affect thing like the actual arm material. The metal wands are simply much quieter in this frequency range! The worst wand I had was an older 3D 10" wand (shiny finish). If you have an arm+cart combo that's quieter, it's probably due to the wand, not the cart. 

One last weird finding - I noticed that even the SUT I choose, and its placement on rack, can have a big impact on feedback. I don't know if that's due to the SUT itself being microphonic, or feedback back into the arm through the cable. The Bob's Devices Sky (lightweight little boxes) gave me the worst feedback problems when positioned on top shelf next to my table, until I moved it to a lower shelf - the it quieted down. The EAR SUT (much more substantial box) has no problems on the top shelf. 

@tablejockey @mulveling @larryi @atmasphere 

so frustrating....thanks for the help ..I wanted to add that the low end rumble is basically like the bottom end is not tight & consistently ringing...even tested with acoustic guitars (no drums) still get the low end rumble..

So the latest is the arm was sent back to VPI for repair of the white lead...when it returns I'm going to try some better isolation ...incidentally my room is heavily treated with sound panels ,bass traps, sound absorbing curtains....

I might try the HW40 feet I have , they seem way shorter than the Prime Sig feet so not sure all will line up with motor? 

I might try the HW40 feet I have , they seem way shorter than the Prime Sig feet so not sure all will line up with motor?

@tommypenngotti Yep I had to shim it with hockey pucks as needed to line everything up. The HW40 feet will help for sure - it’s worth it rearranging for.

The issue as you describe it is extremely similar to what I’ve fought with. In fact with some of my worst configurations, it could get excited to an almost runaway level of that rumbly / hum noise (grows in level on its own, until I mute). And yeah, acoustic treatments won’t do a damn thing about it, either. Best I can tell, the problem is due wholly to structure borne energy, not acoustic.

The top shelf and its support underneath is what determines how much of this energy your table has to deal with. The VPI arms are sympathizing with the energy (less for the metal wands), and the table plinths don’t do much at all to stop it. Squishy feet like HW40 are really your last line of defense. Think if I had a rack with cross-bar support level (at least for the top shelf), and support discs positioned more toward the interior of top shelf, that would help a LOT (e.g. higher-end Critical Mass, or for a LOT less money Adona Reference racks, etc). As it stands, my Sotto Voce rack only supports its top shelf along the very front and back edges (with a few simple rubber bump feet) which I think is a big part of the problem in my case - the CMS Platinum shelf, substantial as it is, acts like a drum skin at the problem frequencies.

Here’s how I "test" a given configuration: lower the stylus in a still groove (turntable at rest!) and turn the system on / un-mute at your normal listening level. Modestly thump the top shelf near your table with a few fingers. That "drum" like feedback level tells you how bad that config is. The worse ones will be much louder per thump, with a very long-lasting ringing effect. Get a feel for what it is now so when you change configs you can meter it against that. An iPhone can record these frequencies just fine, so take videos for comparisons. However, you will need to playback with decent headphones to reproduce those frequencies.

The problem (obviously) gets exponentially worse at higher SPLs. Guys who cap out at 70 - 85 dB are going to be like like "huh? my table is dead quiet!" because they won’t ever hit that threshold to excite these resonances. I listen loud (up to mid 90 dBs continuous), and yeah in this small room with bouncy floors it’s a struggle. My main rig is in a bigger room with much more solid floors, and it was easier (also that table is on a CMS Maxxum which is much better).

Which exact VPI arms do you have, and which is the one that’s been the bigger problem? The metal arms are just much quieter at these frequencies, in my experience. Sure they might "ring" at high frequencies, but that is MUCH lower in level and easier to deal with. 

@mulveling

Great advice , you hit on 2 things that are my life ...Hockey/Drums 😃

Pucks  .....is there some better isolation thing I can stack under? Pucks seem super stiff and could transfer? But definitely HW40’s under table 👍🏻 Also the checking feedback with LP stopped is on the agenda when I get the tonearm back. I have 2 arms . The metal JMW-10 (no feedback) and the 3D printed JMW-10 that came w my Prime Sig (feedback galore)

I was thinking about trading in arm for the Fatboy Gimbal , but if it’s this same plastic resonant material I’m nervous..🤔

My hifi desk/shelf isn’t anything special, just a long cabinet that holds/displays the amps and TT.

Thanks!

I was thinking about trading in arm for the Fatboy Gimbal , but if it’s this same plastic resonant material I’m nervous..🤔

@tommypenngotti I did exactly that move last year - started with 10.5i metal (Nordost) and 10" 3D wands on an Aries 3. Super cool table, but the 3D wand was just awful in my setup, because of this feedback. Unusable. Then I swapped to 10.5i, and everything was was lovely - big surprise, given all the feedback (haha) online about how much better the 3D arm is. I’ve heard a 3DR sound great - in my buddy’s system. He listens loud as me BUT he’s on concrete slab, and it’s no problem there. It even handled a Koetsu Rosewood Signature Platinum so well (with dual pivot), it impressed the hell out of me (I’m a Koetsu collector).

Of course upgrade urge hit fast and I bought a brand new 10" Fatboy Gimbal. It’s a great arm, I really do think Fatboys are the best sounding VPI arms. However, it’s not as quiet as the metal wands in this feedback problem, and it’s not as bad as the original 3D arms. It falls in between. The Fatboys have more rigidity which helps. I think with HW40 feet and Fatboy combined you’ll be fine. That was the case for me.

Of course THEN I snagged an Avenger Reference plus a couple 12" wands - lovely table but same arm feedback issues persist if you’re not careful. And unfortunately, I don’t think those fancy $2300 Reference feet are as effective as HW-40 feet at these feedback frequencies. So I’m really right on the edge of usability with a 12" Fatboy Unipivot (dual pivot). Even my SUT placement next to the table (I guess the lighter SUTs can pickup energy from the shelf and feedback in via cable) can make or break it. Meanwhile I have a JMW-12 metal wand that’s always silent and happy, no problem lol. MANY cartridge and phono stage combinations were tried here. It’s the wands. The Fatboy Uni is a GREAT sounding arm when I can get it right, though. I like it slightly better than the Gimbal. Gimbal vs. Uni vs. Dual doesn’t seem to impact the feedback much. I think materials and structure of wand is what matters here.

However, it does make me think since the 3D and Fatboy arms are a composite structure (reinforcing rods, etc), there COULD potentially be variance across units - some being quieter than others! Hopefully the Fatboys are more consistent because I really like them.