polkalover .. when I rest the needle on the record (record not playing) and I turn the volume up to the 12 o’clock position, I get an incredible amount of woofer vibration from the logans. Same issue when playing a record. I’ve tried:
1. better isolation ...keep in mind record is not playing so acoustic feed back is out of question. The turntable doesn’t have to be spinning to generate acoustic feedback, which is what it sounds like you have here. |
This is acoustic feedback. Just because the frequency is too low for you to hear doesn’t make it not feedback. The trigger could be your footfalls or environmental sounds but that can be enough to set it off.
The simple solution is a rumble filter which will cure it for sure. Otherwise you need much more sophisticated isolation. You did not say how far you can get the table away. I’d say a minimum of ten feet and ideally more. If you are six feet or less then you are making the problem harder to fix. Real isolation solutions for subsonic frequencies are very expensive (think thousands of $) - space and air is much cheaper!
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A situation, if you didn't notice the woofers, that isnt going to harm anything.
ALL system's speakers will do the same with a table.
Lookup subsonic concerns.
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KAB Rumble Filter from KAB USA online. $179.00 Problem solved.
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There are two paths for acoustic feedback, airborne, and structure borne. You may have a problem with one, or both. |
Good suggestion, so many receivers and amps USED to have rumble filters. |
if you use a rumble filter it needs to be really good as i believe the full signal passes. maybe dumb question but are there really good phono preamps that might have this feature?
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tablejockeyALL system's speakers will do the same with a table. Not so. Feedback may be a common problem with turntables, but it is not inherent in all systems. My speakers are flat, in room, to below 20 hz. I have no feedback at any volume level, and my turntable sits remarkably close to one of the woofer columns. It's all about isolation and, imo, mass. |
The KAB Rumble Filter uses all audiophile approved parts. I run mine via the tape loop on my preamp and I hear no difference with it engaged or not, but it certainly stops all the woofer pumping. |
@polkalover - What kind of woofer vibration?...
- does it pulse evenly? e,g, at a partucular frequency (which freq)
- is it spiradic? e.g. only happens when you walk around it
- are all the pulses of equal amplitude or do they vary?
Since this only occurs when the needle is placed on the record and if the pulsing is of a constant frequency and amplitude then it sounds like a resonance issue.
Have you tried varying the bass control knob on the rear of the speaker? Does it make any difference ?
- try one turned up fullty and the other turned down
Have you tried moving the speakers slightly (e.g. 1"-2") further in/out from the audio stand. The resonance may be occuring between the speakers and the cartridge is picking it up.
Maybe it's a standing wave issue?
Just aome thoughts - Steve
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Just wanted to thank everyone for their input. Here's an update:. I purchased Harrison labs 30Hz high pass plugs and although it allows me to play it a little louder the rumble still occurs at about the 2 o'clock position. Once again not playing a record just resting needle on record. So this leaves me with 2 options: 1. Spend some more scratch for the KAV rumble filter and see if that solves it or 2. Sorbothane isolation feet for table. Room reconfig. Is not possible..... additional thoughts, ideas are welcome |
polkalover... rumble still occurs at about the 2
o'clock position. Once again not playing a record just resting needle
on record ... If you hear noise without the platter spinning, then its source is something other than rumble, and is probably feedback.
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That reviewer may have had a subsonic filter(many phono stages do), speakers without very low extension, a room with differing Sabine coefficients, etc. They don’t mention anything, regarding their reference system. It would be simple, to experiment with your tonearm mass/cartridge weight, to see if anything changes. Also, very advantageous to determine at what freq your system(both great pieces, btw) is resonating. |
Just curious: At what level do you have the Bass Control set, on your Logans and- does your phono stage's IEC button, make any difference when engaged? |
The issue simply put: when I rest the needle on the record (record not playing) and I turn the volume up to the 12 o'clock position, I get an incredible amount of woofer vibration from the logans. Same issue when playing a record.
I had the same thing with a Linn LP12, stylus on record (not spinning) volume up, tap the plinth and watch/listen to all hell break loose with feedback. I was sure it was air born feedback after I tried everything even tried suspending the whole TT from fine wire from the roof bearers. The only cure was I put the TT and all the electronics in the room next door and that cured the problem and NEVER SOUNDED SO GOOD especially the bass. GOOD LUCK, after this I went to CD. Cheers George |
@rodman99999 it varies by LP but I usually keep it at -3. The IEC has no effect.
@georgehifi it won’t come to that but it is a frustrating annoyance. Thanks for tips |
That the IEC switch makes no difference, is really puzzling. Given that the woofers are(I'm assuming) pumping with it engaged, their excursions should increase markedly with it off. Are we talking about an audible, "rumble", or subsonic excursions(trying to better understand your issue). |
