I’mhaving 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 creepthe 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!
First look to see how much subsonic turntable rumble is getting through. If the woofers flutter a lot at high volume even with no signal, like on the lead-in and lead-out grooves, or between tracks, that’s one thing.
Also does this ever happen playing CDs?
If you have no problem playing CDs, and especially if you also have a lot of flutter, then yes you need a better platform.
Just not any sort of isolation platform. There is by the way no such thing. What there is is vibration control. This false notion of isolation makes people forget what is so plainly evident, that a box full of sand ain’t gonna isolate nuttin but it certainly will control and eliminate a lot of troublesome vibrations reaching your turntable.
I hear ya on the isolation thing. It does rumble in between tracks. I do not run a CD player, just phono. I’ll keep playing with trying to reduce vibration. Hmmmm
paulgardner My subwoofer will rumble uncontrollably when playing records at a higher volume.
Your are getting "air-born feedback", and it can’t be cured with better stand mounting.
Do this. If you just put the stylus on a record NOT spinning, turn the volume up to your normal position, one hand on the volume control, then gently tap the turntable plinth, you will see you’ll get "runaway feedback", which just gets louder and louder. The only way to cure this is no subwoofer or the turntable goes in another room.
I had the same problem with my 3 VPI tables (I no longer have them). I tried everything under the sun and spent lots of cash on maple platforms, granite, special feet, Target shelf bolted to wall, nothing worked. The KAB rumble filter which goes in either a tape loop or between pre and power amp solved the problem It cost 179.00. It uses all audiophile grade parts inside and there is no loss of bass or any frequency's. I have had many different people over the house who could not hear a difference as I didn't either.
Everyone will tell you it is a band aid approach but it works and totally solves the problem. My new Technics SL1200G does not have that problem, not sure why.
Its unlikely you're getting feedback, unless you have some really lightweight rig with a dust cover sitting on a flimsy particle board rack, something that extreme. In which case, remove the dust cover.
People confuse feedback with rumble and its easy to do since it all seems the same but they're really quite different and its a really hard problem to solve if you can't tell the difference.
There's mechanical vibrations coming from the sub sitting on the floor. There's also mechanical vibrations coming from the rack being made to move by low bass sound pressure. Either way results in added platter/cartridge vibration that can over drive your subs.
A filter is one answer. But this does nothing to address the real problem. The extra vibration is still there, you've only gotten rid of the obvious part to the problem. The guy telling you no one can hear the difference is missing the point. The comparison is not between the filter and no filter, the comparison is between the filter and a rack that lowers subsonic noise down to the same level. Which of course will be a lot better.
The solution is trial and error. It can be as simple as taking something like some lids from a large open mouth jar, turning them upside down, packing with sand and putting the table on them. To at the other extreme filling a box a couple inches deep with sand (always mix with oil so it packs down and stays dust-free) with a platform of wood, MDF or stone laying on top of the sand. To the creme de la creme, a concrete/ABS/sand and granite stand with carbon fiber. https://www.theanalogdept.com/c_miller.htm You will not get any feedback with this, let me tell you!
paulgardner OP3 posts11-17-2019 2:11pmGeorge- I’ll give that a try when I get home tomorrow. Thank you
Yep air-born feedback. I bet nearly 100% it’s your problem.
1: Remember system all on including sub (not in standby auto switching mode). 2: Stylus on a record but not spinning, 3: Turn volume up to your normal loud position. 4: One hand on the volume control, with the other hand solidly tap the turntable plinth with end of your finger .
And watch your "finger donk" on the TT plinth turn into an ever increasing earthquake with airborn-feedback and continue to get louder and louder as it starts to run away and if not stopped will take out your amp and speakers.
The sub is driving the room. Some room are incredibly microphonic. Isolate the sub from the rest of the system by putting it on short stiff springs. You know, like Super Stiff Springs. Trademark. Problem solved! 🤗
Thanks for all the reply’s and ideas, awesome! I’m running a Clear Audio Concept table and the sub is a REL T9i. They’re both very good products so the lack of quality materials in the turntable build is likely not the issue. I will do the stylus down on a still record/finger tap on platter test later today and report back on the weather conditions - earthquake or other! I’m not sure how I feel about a subsonic filter. Maybe as a last resort but moving the table to another room is not really an option - I live in a 2 bedroom condo loft with 20 foot ceilings so it’s essentially one big open space with 8 foot half walls for bedrooms and a bathroom and furnace/washroom being the only closed off rooms. I will report back on my findings!
I should add all (rpt all) components including front end electronics should be isolated. Not only because of subwoofer mechanical feedback but also structure borne vibration. It’s a vicious cycle.🔄
Paul, two possibilities. If your sub has room control turn it off and see if the problem goes away. Then as others have mentioned, feedback which can be worsened further with room control. The feed back can be due to a cartridge tonearm mismatch but can also be due to improper turntable isolation. An SME , SOTA or Basis turntable will never do this.
I will play around with isolation some more. Think I’ll focus on the sub first. I will look at picking up a test record as well. Thanks for the suggestions!
I have Springs for Subwoofers on sale on Audiogon as we speak. Wink wink 😉 By the way, Even if you didn’t have an audible problem with the sub’s woofer the springs improve the sub’s performance per se by allowing it to operate with less distortion. It’s a win-win! 🤗
All the problems lying dormant in the system spring to life, as it were, when the volume is turned up. - old audiophile axiom
It might be your turntable. I had a Concept and it was super sensitive to footfalls. I couldn't walk anywhere near it without the arm jumping around. Granted, I have springy floors and it wasn't very well isolated, but I've had a number of tables before and after it that didn't have that problem. I seem to remember issues with what you've described at high volumes also.
It's surprising and unfortunate, because it does seem to be a solid and well built table. It may have something to do with the magnetic bearing tonearm design.
There are a number of reports of this issue if you do a web search. There are also many who love it and report no problems with it. There seems to be a consensus that it needs to be really well isolated.
I really liked mine and wanted to love it, but it didn't work in my less than ideal setup where many other tables have worked great. You'll notice I use the word "seems to" a lot in my post, there's obviously some supposition on my part, as I was never able to figure out how to get mine to work satisfactorily in my system and I know many others have that table and love it. Do you have another table you can try out and see if it has the same issue?
I don’t have another table on hand to swap in to see if it is indeed the Concept that’s causing the issue. I might give the subsonic filter a shot before giving up on the Concept. I really do like it aside from this apparent issue. Time to play the DIY isolation game!
@georgehifi you were spot on. Stylus resting on a still record then tapped the plinth and the sub rumbled like crazy. Would a subsonic filter fix this or what’s the best solution in you eyes?
11-18-2019 5:27am@georgehifi you were spot on. Stylus resting on a still record then tapped the plinth and the sub rumbled like crazy. Would a subsonic filter fix this or what’s the best solution in you eyes?
There you are. The the initial sound of the "donk" tap of your finger is the first mechanical starter vibration, but the growing intensity of the following earth quake rumble is "air-born" feedback, which you have end of story, don't listen to others trying to sell you stuff like special voodoo springs ect.
You can hang your turntable as I even tried from the ceiling on fishing line and it will still happen.
The only way is to get rid of the broad band frequency that’s doing it (the sub) notch filter may help a little, but it needs to be board band, may as well not have a sub then. No isolation BS in the same room is going to be a fix for this, if hanging the turntable in the air couldn’t fix the problem.
Or move your turntable to a place where the air-born vibrations can’t get to it as much, which is what I did, in the next room. Then I could wack the plinth even harder and only get the initial "donk" sound nothing after it. Then my system sounded awesome in the bass, you won’t believe it, I had sub bass unit’s <60hz (2 x Kef B1814 in 11cuft enclosures each) that were flat to 19hz!!!! Those bass drivers made the Kef B139 look like tweeters
I had the exact same problem, though it was so long ago now I can't recall whether it was with my VPI or my current Garrard 401/ home made plinth. In any case, I contacted Dan Wright at Modwright, and he sent me a few resistors to try on my SWP 9.0 SE Phono Stage, and photos of where to put them on the circuit board.
This worked like a charm, and didn't cost me a cent. Another act of kindness by Dan Wright, he's number one to deal with in my book. I'm certain the subsonic filter you bought will get the job done.
George, Dan - thanks again for your insight and ideas on how I might go about resolving this! I did end up ordering a subsonic filter from KAN Electro Acoustics. Fingers crossed it at least help because relocating the turntable to another room just is not an option given the space/layout I’m currently working with. When the filter gets here and I get a chance to try it I’ll post a quick update. Paul
This filter you bought, is for very low arm cartridge 7-12hz resonance (below 20hz), this you can’t feel or hear, it’s just very slow woofer movement. I think from what you described you problem is far higher, around 30-70hz this you feel and hear like an ever increasing earthquake.
If you have floor standers with half decent low bass as your main speakers, try doing the "donk" test again but with the subwoofer/s turned off this time. try it even if they are just stand mounts also.
And what’s causing the problem with the table? The subwoofer. The REL is driving the room. It’s the structureborne vibration, seismic plus Rel. The resonant frequencies Fr of the cartridge and tonearm are circa 8-12 Hz, the platter can be even higher. Some rooms are incredibly microphonic, especially the upper floors of buildings. Some racks/stands amplify the vibration. The REL weighs only 42 lb so my cryo’d Baby Prometheans would be sufficient to properly isolate the REL. $48 free shipping, cannot beat with stick!
It was in the correct phase when - before you switched the cables or after? When your sub is in correct phase is the turntable problem worse, better or the same as when the sub is out of phase?
Yeah I’m not into the spring thing. Never gonna happen.
The REL has a phase switch. 0 or 180. My system likes 180. Flit it to 0 while music is playing and the Sub rumbles uncontrollably. Earthquake time! I understand that a properly set up REL should go unnoticed but apparently I Guess I like more bass than most “purist audiophiles”. I absolutely love my set up (aside from the recent sub rumble issue) and am blown away by how good some recordings can sound. I’ve always been into listening to music and sound quality but only up until recently (about a year) have I really discovered what a very good stereo sounds like. Partly due to financial reasons. I’ve always had a nice stereo set up but never really nice stereo. It’s a different game when you get into the $10k+ realm. I have a subsonic filter on the way. I’ll play around with that - otherwise I’ll learn to live with a sub crossover/volume combo that sits below the earthquake rumble reaction. My next upgrade is a new phono stage. The MS Phonomena II+ is great but I do miss the all tube experience I once had. A rabbit hole this game really is!
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