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Has anyone had experiences good or bad with speaker isolation or isolation in general ?

hi
i have been enjoying buying and listening to hifi for some 35 years now and have seen many items come and go.I have also been interested in the audio cable discussions and i agree that cables do make a difference how much of a difference is a very individual, and a system dependent situation. There has been nothing that has got me so excited and improved the sound of my system that has ever made me want to really share it with fellow audiophiles until i started to try various isolation products.With so much choice from affordable to very expensive i found the hole subject very confusing and i did not know where to start. After trying lots of various products all shapes and sizes with very different results i decided to read reviews which is something i do not usually do to get some advise.I read a review on the Townshend audio seismic podiums they are isolation platforms that go under your speakers .This company is very famous for isolation ideas and have been around some 50 years based here in the UK they also had a factory in the USA back in the 1980s. I contacted Nick at Emporium hifi  and he agreed to install a pair for me so i could have a listen. My speakers are sound-lab dynastats which i use in quite a small room but with the adjustments give a nice sound. After installing the podiums we both sat down with jaws hitting the floor these podium things completely transformed the sound of my system to absolute perfection. After all this time trying various products under my equipment i have now isolated my speakers and the sound quality is exactly what i believe we all are chasing, my sound-labs are now transparent no more bass problems i have just got one big 3D sound stage the dynastats are now very open with deeper much better bass everything is perfect. I now believe isolating your loudspeakers is the first port of call i was so impressed by the Townshend audio seismic products i now sell them as i have never come across anything that has given my system such a great upgrade , the sound is the same as before but now its just so much better its playing deeper bass but tighter much more resolution and no boom , the midrange is so much more human sounding realistic and spacious with the top end so refined and perfect , is anyone using podiums and had the same experiences i would love to hear from you thank you john 
mains
kennythekey
593 posts
 
Geoff -
Here's the issue. Eliminating my power amps, so only the sub amps are on, I drop my arm on a stationary LP. As I turn up the volume on either sub, l start to get oscillation through the sub. I do not get oscillation if I do the same with my arm up. If I'm actually playing music, I have to turn the sub amps way up before oscillation, so at my listening levels all is good. Back to just the subs on and the arm down with platter stationary, I placed a half inflated bicycle inner tube under my table after I removed the feet. Repeating the original experiment, the oscillation was far worse. So, I'm not sure if I'm fighting mechanical or aerial feedback?
Kenny
geoffkait's avatar
geoffkait
23,365 posts
 
Bicycle inner tubes are not what I would call a great idea. For one thing their geometry is totally wrong and for another noone is sure what pressure to inflate the inner tube. They also lose air pressure because the rubber material is not entirely air tight; thus the inner tube must be pumped up every once in a while. I would certainly try inner tubes under the subs, for lack of something like springs. And inflate the inner tubes with sufficiently high air pressure, maybe 30 psi or thereabouts, so they don’t compress too much under the weight of the subs - and are stable. I now offer Super Stiff Springs for heavy turntables and subwoofers, speakers that are not too top heavy, as well as heavy amps as fate would have it.
kennythekey
593 posts
 

Yeah, that inner tube was just a test requested by my turntable builder to see what the results would be. The results were not good, and how much to inflate was a guess.

I'm having second thoughts if this is truly a mechanical feedback issue, so I'm not going to throw darts at a solution I'm not sure about. For example, the guy who distributes my cartridge had me reverse the phase of the ICs going from my line stage to the sub amps. He thought it was phase doubling. This actually killed the oscillation with the arm down on the stationary platter. However, when I play my turntable with only the subs running, I still get the oscillation at the lower sub amp volume level. So, part of the problem resolved, but still a mystery to fully resolve.

My current MC cartridge, uses a different moving coil method (cross ring), and I'm wondering if this may have something to do with it. My dealer, has sent me another lender cartridge to try in order to find out.

My desire to stabilize my rack, is to keep my cartridge safe.

Kenny

toddverrone's avatar
toddverrone
840 posts
 
Kenny - springs are way better at vibration isolation than an inner tube.

I recently got rid of the inner tube I had under the maple butcher block my turntable rests on. I bought my springs from Grainger after doing a few simple calculations to determine size and spring rate. Geoff’s springs aren’t that much more expensive and you wouldn’t have to do any calculations.

My test for the different means of isolation involved hitting my equipment stand with the arm down on an LP but the turntable not spinning. With the turntable sitting directly on the stand, the hits were audible as loud thumps. With the butcher block on the inner tube, the thumps were diminished in volume. With the butcher block on the springs, I had to increase the force of my hits to even get any thump. So springs may help your problem even if the inner tube did not.
kennythekey
593 posts
 
Toddverrone,
I am not doubting the benefits of using springs, when applied correctly will provide benefits against mechanical isolation. I had mentioned that I'm getting upgraded feet that are made by my table's manufacturer that are designed with a built in spring system. I am also getting an upgraded bearing, but that's besides the point. My table already sits on a Silent Running Audio isolation platform, and with that in place, knocking on my rack with the table sitting directly on the rack, is louder than with the SRA in place.

My bigger point is that I can eliminate the oscillation just by changing the phase of the subs IC inputs. If my problem was due to vibration from mechanical feedback then when I switch the phase of the outputs to my subs I should continue to have oscillation if the problem is vibration. In fact, the vibration is just as strong regardless of phase.
Kenny
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