AudioCircle
Industry Circles => GR Research => Topic started by: Captainhemo on 7 Feb 2017, 11:01 pm
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Has nayone running the OB servo subs and a turntable run into low frequency noise being passed on to the subs which in turn creates oscilation ?
I know one fellow (OE) who has similar issue, he gets around it by turning the subs volume a bit lower while listening to vinyl, he also says using the rumble filter just makes it worse.
Is this common with TT's ? Is there a work around ?
jay
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It varies with the record I'm playing. When it happens I switch the rumble filter on and that usually works for me. I have my turntable wall mounted which seems to isolate it better than the stands I've tried.
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It varies with the record I'm playing. When it happens I switch the rumble filter on and that usually works for me. I have my turntable wall mounted which seems to isolate it better than the stands I've tried.
Thanks, I'll pass that on :thumb:
jay
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I have Brian working with me to solve that particular customers issues. Something else is not right on his set up. The rumble filter will pretty much kill any DC issue. So something else is a miss.
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Cool, sounds good
jay
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I have had the same issue, am very careful with volume when I am using my (wall mounted) turntable.
So I too will be happy to hear of improvements.
It really is a tough world: having great sounding bass with excellent frequency extension, thus exciting the oscillation frequency in your beloved turntable :lol:
Best regards,
The Priest
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I have a wall mounted TT (Well Tempered Amadeus) and a pair of Super Vs. I have had no issues whatsoever with low frequency oscillation.
Shakey
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Some of those turntables try to pass some really low wavelengths. The rumble filters should handle it all unless there is something else going on. If it is sending an oscillating DC signal then it might be impossible to control.
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Depends on the turntable of me, but I have the 3-8" which are probably much more turntable friendly. The Pro-Ject TT had a lot
of problems with the subs. Herbies feet and a TT mat helped quite a bit but did not completely eliminate it. Purchased a VPI TT and in
stock condition, with no Herbies, have had no problems.
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I have a Project RPM 3 carbon TT in my system with the dual 12" servo subs. In addition to the rumble filters in the subs my phono preamp also has a rumble filter.
The TT is pretty well isolated. I's on the same equipment stand as all the rest of my audio equipment but I have it triple isolated. On top of the equipment rack I have Herbie's fat dots, a piece of 3/4" MDF is on top of the fat dots. Next comes more fat dots than a 2-1/2" thick piece of maple (woodworking workbench top), more fat dots are placed between the maple and the TT.
Even with all that isolation, I have some older albums that need both rumble filters on. New albums that are in good condition usually don't need the sub's rumble filter.
Mike
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It could also be that the sub is making audible what was already there but unheard (because the owners speakers don't reproduce the very low frequencies that the sub does)---the low-frequency resonance created by a mis-match between cartridge compliance and tonearm mass. A cartridge and arm need to be paired such that their combined low-frequency resonance is located between 8-12Hz, 10Hz being optimum. If the cartridges compliance is too high for the effective moving mass of the arm, or conversely the arms emm too low for the cartridges compliance, the resulting resonant frequency of the pairing will be too low, below 8Hz. The lower the frequency, the worse. A very low-frequency resonance can cause tonearm instability, power amp distortion, and woofer pumping.
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I'm not TT guy so I don't a whole lot about his gear but I do know it is supposed to be world class and it was all setup by Jeffrey Catalano of High Water Sound so there should not be asetup issue ...
Trying lots of different setting but still gettng major oscillation when turning up the gain
jay
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Okay, I just went over this with Brian at Rythmik Audio.
The fact that you can turn on the rumble filter and the oscillation gets worse confirms that you have a mechanical feedback issue. It can also be confirmed by moving the woofers further away from the turn table.
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He does have the subs inboard of his mains, I'll pas this on to him
(http://www.audiocircle.com/image.php?id=155639)
jay
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I have the same problem with my Merrill Heirloom table with Morch DP-6 arm and Micro Benz Wood body cartridge. The arm tube used is the one recommended by Morch...So I doubt I would have a mechanical mismatch. My table is wall mounted on a Target wall mount. The table is located in a stairwell behind the system and behind a door so it is pretty well isolated from the system.
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I have the same problem with my Merrill Heirloom table with Morch DP-6 arm and Micro Benz Wood body cartridge. The arm tube used is the one recommended by Morch...So I doubt I would have a mechanical mismatch. My table is wall mounted on a Target wall mount. The table is located in a stairwell behind the system and behind a door so it is pretty well isolated from the system.
Hmm. The Morch is a very low mass arm, the Benz a rather low compliance cartridge. Have you put the numbers into the resonance calculator on the Vinyl Engine site? It could be that you have a mismatch, the arms low mass and the cartridges low compliance creating a very low frequency resonance.
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Shouldn't room treatment, in particular corner bass traps help?
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Turns out that engaging the rumble filter does solve my problem. I know that when I purchased the arm tube from Morch the mass of the "Green Dot" arm tube was supposed to be the correct mass arm tube to match the Benz woody according to Morch.
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hey folks, just a quick follow up on this topic...
After trying pretty much everything we could think of, the customer went ahead and ordered a set of Townshend Isolation Bars for his subs. Here's a copy of his email:
"I just received my Townshend Isolation Bars and stuck them under my subs. My oscillation issue is 100% cured, even at the sub amps full volume! It doesn’t matter if the rumble filter is on or off or where I set the frequency switch or any of the controls. Highly recommended for all those vinyl guys with subs."
(http://www.audiocircle.com/image.php?id=162206)
jay
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A set of the Townshend Seismic Pods (the things bolted onto the ends of the bars pictured above---they are available separately) are at the top of my list of "buy as soon as possible" items. They're not cheap, but they are worth their price. There is a new product that may give them some tough competition, the Isoacoustics Iso-Puck.
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hey folks, just a quick follow up on this topic...
After trying pretty much everything we could think of, the customer went ahead and ordered a set of Townshend Isolation Bars for his subs. Here's a copy of his email:
"I just received my Townshend Isolation Bars and stuck them under my subs. My oscillation issue is 100% cured, even at the sub amps full volume! It doesn’t matter if the rumble filter is on or off or where I set the frequency switch or any of the controls. Highly recommended for all those vinyl guys with subs."
(http://www.audiocircle.com/image.php?id=162206)
jay
The owner of the OB/Dipole Subs has posted on Audiogon about the success he had had in curing the problem caused in his turntable from all the new bass the subs are producing, by putting the subs up on the Townshend Seismic Bars pictured. Little by little, audiophiles are learning of the sub! Great job of assembling and finishing the subs Jay, done to match the owners speakers.
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Hi Folks,
Just now noticed this thread. Here's a description and pictures of a 1 Hz isolation stage contraption I built years ago for a TT wall mount to solve this same problem. Been working fabulously for me ever since.
http://www.audiocircle.com/index.php?topic=82514.msg1306519#msg1306519
Cheers, John
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Hi Folks,
Just now noticed this thread. Here's a description and pictures of a 1 Hz isolation stage contraption I built years ago for a TT wall mount to solve this same problem. Been working fabulously for me ever since.
http://www.audiocircle.com/index.php?topic=82514.msg1306519#msg1306519
Cheers, John
Geoff Kait, frequent contributor on Audiogon, proposes hanging a turntable shelf from the ceiling with bungee cords!
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A set of the Townshend Seismic Pods (the things bolted onto the ends of the bars pictured above---they are available separately) are at the top of my list of "buy as soon as possible" items. They're not cheap, but they are worth their price. There is a new product that may give them some tough competition, the Isoacoustics Iso-Puck.
Indeed. But there is something better than the puck. The Isoacoustics modular design is both inexpensive and custom designed for your particular sub, a patented design with credible measurements. I would recommend the customer return the Townshend and purchase the Isoacoustics. Many of the Isoacoustics products are inexpensive with the exception of the "pretty" looking GaiAs because they primarily cater to pro audio (and the GaiA's cater to oddeophiles). I use their stands for all of my subs. Although the stands come unassembled it takes just 30 min to build them.
http://www.isoacoustics.com/home-audio/
Best,
Anand.
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I'll second this. I use Isoacoustics in three of my systems. They are really effective and mostly inexpensive.
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Indeed. But there is something better than the puck. The Isoacoustics modular design is both inexpensive and custom designed for your particular sub, a patented design with credible measurements. I would recommend the customer return the Townshend and purchase the Isoacoustics. Many of the Isoacoustics products are inexpensive with the exception of the "pretty" looking GaiAs primarily because they primarily cater to pro audio. I use their stands for all of my subs. Although the stands come unassembled it takes just 30 min to build them.
http://www.isoacoustics.com/home-audio/
Best,
Anand.
Thanks for the tip Anand. I've been looking at the IsoAcoustics website, and Guitar Center is a dealer! That usually means significant discounts---I buy some of my drum gear from them, and they sell it at about a third off list. What attracted me to the GAIA is that it can be bolted onto the Sound Anchor stands I have my speakers mounted to. But I'll look into their other products too. The new (they're not in stores yet) Iso-Puck is made for not speakers, but for components, and they are about $30 apiece, much less than the Townshend Pods.
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I use the Isoacoustic stands too. Not fun to move but effective.
(http://i576.photobucket.com/albums/ss207/corndog642/OB%20Subwoofer/4B55D256-55C0-4C37-81C2-327080B095D5_zps8krcdd2x.jpg)
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One thing you guys need to keep in mind with these devices is the type of floor that you have.
If you have a wood floor, suspended floor, and any type of floor that can move, then these devices can really help keep the speakers from mechanically moving or flexing the floor. And the benefit can range from minor to significant as the flexing or moving floor in turn moves the speakers, electronics, turn tables, etc.
And they aren't technically isolating the speakers from the floor. The speakers are still coupled to the floor. What they are doing is applying a damper. It is just like the car that you drive. The shock absorbers damp the ride and give you a smooth ride. But the car is not de-coupled from the road. The car is still coupled to the road via the wheels and tires. Likewise these stands are still coupled to the floor but there is an added damper or shock absorbers.
However, if you have a solid concrete floor then your best option is to spike the speakers straight through the carpet and onto the floor so that they do not move.
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Indeed. But there is something better than the puck. The Isoacoustics modular design is both inexpensive and custom designed for your particular sub, a patented design with credible measurements. I would recommend the customer return the Townshend and purchase the Isoacoustics. Many of the Isoacoustics products are inexpensive with the exception of the "pretty" looking GaiAs primarily because they primarily cater to pro audio. I use their stands for all of my subs. Although the stands come unassembled it takes just 30 min to build them.
http://www.isoacoustics.com/home-audio/
Best,
Anand.
And you can see here how they're shipped and then assembled.
http://www.audiocircle.com/index.php?topic=149780.msg1605230#msg1605230
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I have always spiked my speakers to the floor, my last couple of houses having a concrete-floored listening room. But my new (and final!) room has a suspended wood floor, and it's a kind of bouncy one. I'm going to crawl underneath, and see if I can add some pillars (4 x 4's) to brace it stiffer. At least my turntable, SACD player, and tube electronics are right up against an exterior wall, the stiffest part of the floor.
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I wonder how these The Isoacoustics modular stands would work on a speaker like the Super V?
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I wonder how these The Isoacoustics modular stands would work on a speaker like the Super V?
Don't know but they definitely add height. When I used their calculator to determine what modular stand the NX-Otica Monitor/dual 12 H-Frame combo needed, the recommended stand was 5-1/5" high.
I would expect the Super Vs to be the same.
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Don't know but they definitely add height. When I used their calculator to determine what modular stand the NX-Otica Monitor/dual 12 H-Frame combo needed, the recommended stand was 5-1/5" high.
I would expect the Super Vs to be the same.
I didn't think about that, I can't have mine any higher than they are as they are already taller because they were built to look like the Super 7. They aren't that tall but taller than a normal Super V.
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Don't know but they definitely add height. When I used their calculator to determine what modular stand the NX-Otica Monitor/dual 12 H-Frame combo needed, the recommended stand was 5-1/5" high.
I would expect the Super Vs to be the same.
All the Modular custom Isoacoustics stands are 5.5 inches in height. So you have to accommodate for that or try one of their other stands which are height adjustable from 3 inches to eight 8 inches. The other option is just getting the GaiA footers which are more expensive due to looks and marketing but not due to performance.
Best,
Anand.
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If the stand allows it, having the back of it a little higher than the front will point the speakers down toward the listening position, solving the height issue.
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If the stand allows it, having the back of it a little higher than the front will point the speakers down toward the listening position, solving the height issue.
Some of their stands allow for tilt adjustment like you suggest, but the Modular series isn't one of them. The ISO series, and the Aperta series do.
Best,
Anand.