Would an Isolation TT platform further improve my TT?
My new Luxman PD-171 A TT weighs around 55 lbs. and it sits on a heavy audio stand. The floor is carpeted w/a cement base. Prior to this TT I had a Linn w/was much more sensitive and didn't need an additional stand. I wonder if adding an isolation platform would be beneficial to my current TT. I was looking at Butcher Block Acoustics and MDF W/Lead Core and Sorbothane Feet.
Adding more mass to your setup is unlikely to address the one remaining source of vibration that you are not currently tackling -- subsonic or seismic vibrations that are being passed to the table from earth and result from traffic, construction or seismic activity.
Solutions such as a Minus-K platform or a Herzan like active isolation system would be worth exploring, but are both very costly. The poor man's alternative is suitably tuned springs, perhaps a set of such under one of the platforms you are looking at would be appropriate
I have always found that the more rigid the support, the tighter, more incisive and clearer the sound. Damping of the support by using wood or "absorbers" softens the sound. Marble and glass sounds etched while oak sounds warm etc. I'm old school and have to be convinced otherwise but spikes, cones and inertia allow the table to be as fixed as possible. There is also a school of thought where springs in cups provide both isolation and rigidity at the frequencies that matter so look into that philosophy also.
Symposium acoustics sells their Segue ISO platform for just this reason, they use their sandwich technology and add a set of 5 special springs to the bottom, I use one on my 70lb Prime on top of a 3" slab of butcher block on top of a lead balloon turntable stand and in another system it really earns praise supporting my Origin Live setup in a much more needed application. These are less than a $1000.00 and available for different weight loads. Enjoy the music.
Vibraplane ELpF 95% at 10Hz - and a rather pronounced bump at its natural frequency of appx 2Hz - $2.5K plus compressor
Minus-K CT-1 99%+ at 10Hz (vertical), 95% or so (horizontal), natural frequency vertical 0.5Hz (good) but horizontal 2.25Hz (not so good) - $5K
Herzan TS-140 99% at 10Hz in all 6 axes, 90% at 3.5Hz, natural frequency <0.5Hz - $10K
In others words the extra money goes to dealing with 3-10 Hz and in more degrees of freedom. As 3-10Hz is where seismic activity is (pace Townshend et al) I’d at least go with the Minus-K as this is the sweet spot for performance vs price and on a rigid stand which isolates form horizontal transmission (i.e. translates seismic activity into mostly up-down) should perform well. Plus the Minus-K is completely passive.
Also adding seismic isolation will also potentially change the sound of the table
As @noromance noted
I have always found that the more rigid the support, the tighter, more incisive and clearer the sound
The same is true for true seismic isolation -- you will get an even more clear, direct, un filtered and accurate presentation of the LP. Frankly what this means is that a lot of what many people like about analog ("warmth", "bloom", "space") is sharply diminished - if it's not present in the recording.
The reason is is because a lot of these apparently positive benefits are colorations from external vibration and taking it out at first listen can be shock -- LPs sound a lot more like digital in that regard after isolation. But the plus side is unparalleled L-R clarity, greater tonal variety, better micro dynamics and all around an ability to more closely engage with the disc. This really pays back on classical but if your taste runs to rock you may prefer the "before" result ... I've been able to do this test many times with my Herzan as you can switch it in and out and a fair minority of listeners prefer the sound without it on
Vibraplane (I have one) works great. Others use the Minus-K with success. As mentioned earlier in this thread Herzan is a great device, but quite expensive
@luxmancl38, although I’m a great believer in isolation I wouldn’t try too hard in your case. The PD 171 is already one hell of a record deck.
Your existing stand/concrete floor will filter most of the higher level seismic garbage (a la Technics SP10 stands of yore). The decks own isolation system will do most of the rest. To go further you might need more than sorbothane ie high compliance springs. But then you risk lateral stability issues.
All major parts are attached to a 15mm thick aluminum plate which connects to the main chassis by our original under-slung (hanging) method, successfully achieving both high rigidity and vibration damping.
The motor and the power supply transformer, which can cause vibration, are attached using floating mounts to achieve a higher signal to noise ratio.
Four large caliber spring-and-rubber insulator feet directly connected to the chassis prevent feedback and external vibration transmission.
In addition, the hybrid vibration damping structure of the metal chassis and wooden exterior contributes to a high level of sound quality.
Both the vibraplane and my Nimbus single airspring platform of yore employed “underslung masses” to achieve very low Fr isolation and lateral stability. The Nimbus also employed a large aux air canister to boost the effectiveness of the single relatively small air spring. An air spring on steroids. Most iso stands cannot isolate in the rotational directions, which are also important. Isolation effectiveness is proportional to the ease of motion in a particular direction.
According to the last two posts it seems the the Luxman has a built in Isolation system w/the spring insulator feet. I wonder putting this TT on a block w/more isolators would diminish the sound. Any thoughts and opinions.
The problem for two stacked iso (spring) systems is they will interfere if the Fr resonant frequencies are close to each other. My Nirvana 2 stage isolation base has two stacked heavy mass-on-spring layers, where the Fr for each stage is predetermined to not be close enough to interfere. The lower layer of springs supports a much higher load than the top layer of springs. If two spring systems are arbitrarily stacked it will be like a car going down the road with two shock absorbers per wheel. It would not be smoother, it would be very bumpy.
I have always found that the more rigid the support, the tighter, more incisive and clearer the sound. Damping of the support by using wood or "absorbers" softens the sound. Marble and glass sounds etched while oak sounds warm etc. I'm old school and have to be convinced otherwise but spikes, cones and inertia allow the table to be as fixed as possible.
The best isolation occurs when there is a great ease of motion. Therefore, ironically and perhaps counter-intuitively, a flimsy and flexible stand would sound better than a rigid one. A rigid frame actually transfers vibration more efficiently than a rickety frame.
Would you put performing musicians on active isolation platforms too ? Remember, seismic activity, traffic etc. Only passive isolation, my friends, active will introduce subtractive colorations - often the worst kind of colorations.
@inna that is a nonsensical comparison. The task of a stylus retracing the groove is to all intents exactly the same as a microscope or scientific instrument and hence solutions that work for the latter will assist the former. This is one area at least where there is hard and obvious science and designers like Mark Dohman have integrated these approaches into their tables
you are right regarding subtraction however, for example subtraction of motor noise, as you can clearly see in the traces posted in my system ... 😉
and Geoff while I agree in principle I should warn that if you are thinking of using an active or spring based approach a rigid support is the way to go, lest the problem of conflicting spring Fr you referred to, or potentially (in the case of a Herzan) even feedback!
A rigid frame actually transfers vibration more efficiently than a rickety frame.
Correct! Well, even a stopped clock....
But even then its not really right now, is it?
What about frequency? What about amplitude? How much and how fast?
Because, there’s this thing, and its kinda old school, really old school in fact, probably not something they teach theoretical physicists these days, but back in the day we called it Newton’s Law. They even made us memorize f=ma. Force equals mass times acceleration. Woo-hoo! I still remember!
Anyway, and I know math is hard and everything (not to mention beneath a reigning theoretical physicist) but it seems to me that from this equation if you use enough m then even a lot of f is gonna result in practically zero a.
But I dunno. Maybe codename should check the math for me?
I don’t see rigidity in the equation F=ma. You must have better eyes 👀 than I do. The problem generally for rigid racks is they move right along with the entire building’s motion. Even something as massive as a building is moving in all 6 directions due to seismic type forces. That’s why decoupling the component is the only real solution to the low frequency vibration problem. Mass per se doesn’t save you.
Seriously this is all you need: AT616 Pneumatic Insulator, on 4 of them you can place any equipment from 10 to 60 kg (and level each insulator individually). They are very rare, i've been looking for original manual for a long time and finally i got it, very impressed by the data in the manual. I am a Luxman owbner too (PD-444), Stillpoints can be an option too if you want to replace stock footers.
Re pneumatic isolators, it might be obvious, maybe not, but using three pneumatic isolators, If it can be done with stability, is better than using four. At least theoretically. The reason is because the total spring rate is the spring rate per isolator x the number of isolators. And since resonance frequency Fr of the system is a function of total spring rate (and mass) you will get lower Fr with three isolators, all things being equal. My original Nimbus employed only one (!) pneumatic isolator, which is how I got the Fr down below 1.0 Hz. As opposed to air bladders and bicycle inner tubes, tall and narrow pneumatic isolators have the ideal geometry.
Am presently putting together my TT isolation package from Symposium. Interestingly enough the Segue Iso platform on 5 springs sits on a diy butcher block on 5/8" treaded brass rod. I've hesitated anchoring this to the wall even though I have angled straps that can be attached to the concrete wall through the sheetrock and the butcher block getting pretty good stability. Question is does the wobbly triple butcher block actually give me some isolation or should I strap it to the concrete wall? I have had some footfall problems but for the most part things have worked pretty well before the platform.
For turntables the primary problem is the resonant frequencies of the tonearm and cartridge are very low, circa 10-12 Hz - too low for the acoustic waves from speakers, but just right for very low frequency seismic type vibration, you know, the ones coming up from the floor. Thus, the tonearm and cartridge are excited by seismic type vibration in the range 10-12Hz. So, the answer is YES, turntables should be isolated. Final answer. 🔚
Which gets us nowhere, since it is still begging the question: How?
The obvious answer everyone comes up with is something soft. Think inner-tubes on the DIY cheap end, Seismic Shelf or whatever on the spendy end. The problem with all of those being they still need to be tuned or balanced if you prefer.
Less obvious is use something sufficiently massive and solid. Go massive enough and at some point the thing simply will not be capable of moving at any but the lowest subsonic frequencies.
Its even possible, if you want to go to all the bother, to calculate based on dimensions and mass exactly what those frequencies will be. Or you could just build one, jump up and down enough to get it rocking, and make a pretty good estimate. Mine is way down in the low single digits.
There's another one the isolationists never seem to answer, and that is the question of: Which matters more- vibrations that are external, ie a part of the environment? Or internally generated?
The answer by the way is: Both. In many if not most, or maybe even all situations the turntable itself is the greatest source of vibration. Given the wackiness of some contributors this might be a good time to say for the record I don't mean during earthquakes. But most other times, just sitting there playing a record, even in your rickety room, the turntable itself is your main concern in terms of vibration control.
Which means, of course, that regardless of what you use or how perfectly it isolates you still have to deal with the question of the very first material the component rests on. Because whatever that is, is going to determine more than anything else the nature of the vibrations reflected right back up into the table.
That's why vibration control is not just words to say, but rules to live by. Isolation is only one aspect of vibration control. I seriously doubt it is even the most important.
The big problem with the “heavy and massive” approach is the entire building is moving, thus everything that’s not decoupled from it is moving right along with it. The mass of the building itself cannot withstand the enormous forces produced by seismic type vibration. “Resonance Control doesn’t work for very low frequencies or is very ineffective. That’s where isolation steps up to the plate. Pretty basic stuff.
What ever became of Torlyte? It was claimed to be stiff, but how stiff can very thin strips of wood be, even if fabricated into a honeycomb structure? There was one valid claim made for it: it's very low mass did not store and release energy. The stuff was like balsa wood!
For an iso stand stiffness is highly desirable for the top plate since a stiff top plate better resists bending forces, I.e., rotational seismic forces. This is why 3” maple boards sound better - generally speaking - than 1” maple boards. They’re stiffer. It’s also why some of the big commercial iso platforms use thick granite slabs for the top plate. It’s also why I use thick granite or bluestone slabs for my stands sometimes.
You guys sometime make me want to pull out whatever hair I have left. You are spending someone else money without analyzing the situation. The TT is sitting on a heavy stand on a concrete floor. There is no isolation platform that is better than four inches of concrete and there is no isolation platform that will help in case of an earthquake! If you are more worried about isolation then get a SOTA or an SME or a Basis. Those turntables do not care what you put them on. Luxmanc138 spend your money on another cartridge or more music or taking the wife out. Buy her some flowers. Your turntable is just fine where it is. Don't fix problems that do not exist.
I already explained that the building and everything in it - including the cement slab - are vibrating right along with the Earth crust motion, at frequencies between 0 Hz and 20 Hz and higher. The peak frequency of Earth crust motion is around 1-3 Hz. Now, I’ll grant you, that cement slabs are not very affected by rotational forces.
And, the seismic vibrations traveling across the Earth's crust are, Max Townshend claims, many times greater in microns than is the distance a tweeter travels when reproducing a not-that-high a frequency. As are the vibrations that swamp the squiggles in the LP groove the cartridge is attempting to measure.
Not to be too picky ⛏ but it’s actually that the Earth’s crust is moving like a wave, that’s what produces the *very low frequency* up and down movement of the building, and the horizontal movement of the building and the rotational forces that try to rotate and twist the building. It’s just like someone shaking out a carpet. This is not to say other things produce seismic type vibration, you know, wind, wave action, traffic, subways, footfall, fans, etc.
Gee, it seems as if you just can’t get turntable isolation low enough. Not easily anyway. Even <10Hz resonance might not be enough for optimal performance.
Apart from totally over the top designs like the Continuum Caliburn and its Castellon stand, it seems as if most designers are happy to settle for just "good enough" isolation.
On the other hand if Michael Fremer’s YouTube videos comparing the Caliburn to the Technics SL1200G are anything to go by that might be enough.
"For an isolation system to work, the ideal support structure must be infinitely stiff, otherwise the movement of the stand will interfere with the isolation system.
To achieve the best possible result the Castellon uses a nautical turnbuckle system which exerts a significant amount of force to cross-brace the vertical legs and resist rocking motions."
Huh? Isolation stands for audio applications have routinely gotten the resonant frequency down to below 10 Hz, almost any of the usual suspects have Fr around 3 Hz or less. The Champs at Fr are my Nimbus Sub-Hertz Platform at 0.5 Hz and the Minus K, also around 0.5 Hz. Without jumping through a whole lot of hoops it’s fairly easy to obtain 3Hz. The trick is getting isolation in more than one or two directions, of which there are six, actually a lot more if you count the boatload of direction in the horizontal plane. Zee plane, boss! Zee plane!
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