Back in April, I succumbed to the analog rabbit hole and bought a Mofi Ultradeck M+ turntable, and PSA Stellar Phono Pre.
Initially, I connected the Phono Pre with Iconoclast interconnects to my BHK Pre–> BHK 250 amp → FR 20s.+ REL T9/x pair.
However I noticed the RELs were oscillating very very fast, potentially the FR20s too although not that noticeably. This got me worried about their integrity of the speakers and subwoofers during prolonged listening sessions. Is this damaging the woofers?
A quick google search and apparently this issue is not that uncommon. The consensus was to attribute this to subsonic resonance from the TT cartridge and to get a subsonic filter (apparently many phono pre have this function built-in but this is not the case with the Stellar phono pre)
In the end I bought a KAB Subsonic Rumble Filter which did reduced the excess subwoofer activity…
But… Now I am forced to connect from the Pre Phone to the BHK Pre with two sets of not so nice RCA interconnects interconnect instead of my prefered Iconoclast XLR.
So here are the questions:
Is the excessive rapid movement of the subwoofers really detrimental to the RELs and (worse) the FR20s?
If so, is there any other method to avoid this without having to resource to a cheap subsonic filter that would allow me to connect the Phono Pre to the BHK 205 using balance connectors?
P.S #1: I tried using a PSA PowerBase as the TT platform but the issue persisted.
P.S.#2: I cannot use a wall shelf for the TT, it has to sit on the audio rack.
Do your speakers/subwoofers exhibit this “oscillation” with the system on but not playing a record?
In what way is the sound quality affected by this?
Years ago I took the grilles off of my subs and noticed what I thought were some crazy movements of the woofer cones. I’ve had these particular subs (REL R-328) for 11+ years.
They continue to do what they do (SQ-wise) admirably.
Thank you for your response.The fast woofer push and pull only happens when the TT is playing (without the rumble filter in-line). Digital sources do not have this issue. I have been told but I am not certain, that the rumble comes from resonance between the cartridge and tonearm that is picked up by the phono pre.
Whether the quality is affected is a really good question. Unfortunately cannot do A/B testing but I suspect it may be. I just would prefer not using the filter and connect with the balanced interconnect but I am afraid this may damage the speakers and subs.
It’s a side effect of a stylus reacting to vertical motion due to the imperfect flatness of LP playback. It can cause both excess excursions of the sub driver and/or over driving the sub amp. That’s why the subsonic filter reduces it, though that can introduce other issues as any analog filter does.
Interesting. I too had a REL, a Mofi Ultradeck M+ turntable, and PSA Stellar Phono Pre. I did not have the “rumble” that you describe. I did have the TT on an oil and buckshot filled platform - I wonder if this prevented the issue you describe.
Possibly an arm/cartridge mismatch (outside chance)?
If there’s enough space in your rack an isolation platform or footers might help; if this affected the woofer pumping then you would know that’s the problem.
Flooring is ceramic tiles and rack is a Pangea Vulcan X-Brace. I think part of the problem may be the closeness of the right speaker and sub to the rack creating a feedback loop.
Thanks for the suggestion. The cartridge and arm are both Mofi Electronics (same as the TT) and they came preinstalled as part of the purchase. I will try a Zazen or perhaps a Fluance IB40.
I live in an old house with a suspended floor. My turntable would actually jump grooves when I walked over to it. The solution I found was to place thick Sorbothane pucks under each of the turntable’s feet. I haven’t had any problems with feedback since.
Like previously suggested, I’d start diagnostics by first disconnecting the sub in close proximity and then seeing if the problem diminishes. Then, see of the problem increases as the main speaker volume goes up. NipperDog’s suggestion is also a good place to start and it doesn’t cost a lot to try.
I will try disconnecting the right speaker and sub to confirm though I do not have the space to move them further away, or the TT, if that resolved the issue.
I tried disconnecting the right speaker and sub (closest to the turntable rack) and by-passing the rumble filter bu the left subwoofer still showed the same excessive movement, so it does not seem like the proximity of the speaker and sub to the TT was causing the rumble.
Isolation. Get some nice pointy feet or something very soft. For giggles, put a folded large bath towel under it and put a record on. It’s free and it’s easy. Skies the limit for special feet, platforms, even active vibration cancellation devices. So much to look forward to.
Another cheap solution is a slightly inflated bicycle inner tube under the turntable. Vary the air pressure for the desired effect. If it mitigated the problem it can be sandwiched between two platforms of your choosing.
and bought a Mofi Ultradeck M+ turntable, and PSA Stellar Phono Pre.