Springs under turntable

MC, You wrote, "Audio is full of complex concepts and this is a big one: human beings DO NOT hear all frequencies the same."  Yes, that's right; it's called the "Fletcher-Munson Curve", and you didn't invent it.  It's why once upon a time a conventional receiver or integrated amplifier had a "Loudness" contour knob on its front panel.

Then you wrote, "So if there's no location information, and moving the subs around by feet all over the room never alters any bass detail, how can it possibly affect (nonexistent) bass detail if a spring lets a sub move a millimeter? Rhetorical question. It can't."
Here you are conflating location information with distortion.  If the sub moves in response to a low frequency audio signal, that means that some of the energy in the signal was lost in doing the work necessary to move the speaker.  This could cause an aberrant presentation of the musical signal at certain frequencies, due to loss of energy at certain frequencies.  That phenomenon is a form of distortion. So, in my opinion, it is best to anchor a subwoofer as firmly as possible in the listening environment.  You can argue the other side of that question, but not using the rationale presented in your last post.  You'll have to do better.  I don't disagree with your bit about bass location.  But I will turn your conclusion around; if the springs do nothing to affect bass detail or a sense of bass location, then why use springs at all?

MC, I wonder about this too, especially when people talk about the bass response of headphones.  Duke is a great guy. One of the best and most honest people in the audio business.

mahgister, You may hear what you say you hear, but the phrase "damp the internal resonance" as a mechanism for what you hear is unclear.  In other words, as is so often the case in this hobby, we have a phenomenon on one hand and a hypothesis on the other, and we marry them often without much evidence.  Can you say how a mass on springs placed on top of a cabinet can "damp the internal resonance"?  I do believe that just placing a  mass on top can lower the resonant frequency of the cabinet, but why the springs?

uber, If your cat is big enough to nudge a 75 lb weight, I am more afraid of IT than I am of the weight falling on anything.  I don't know if I want to get into it, but I don't see the added benefit of putting springs under a weight to be placed on TOP of a speaker, although a weight per se can be beneficial, and I do that myself.

Whatever gets you through the night.

Platter and top surface of plinth should both be level, or both should be on the same plane even if not perfectly level. Otherwise, you might have an issue with the tonearm mount not being on the same parallel plane with the platter, which would mess up your alignment for sure. Ideally it should not matter where you put the level on the platter, unless you have a deliberately dished platter, in which case yes put it in the center of the platter.

But of course.

“Butte”, a nice town in Montana.

This is why I use Delmonte Mandarin orange slices in water, in small cans, as my turntable isolation devices. I use three of them to support a slate slab containing a turntable chassis, either Denon DP80 or Lenco. I support the weight of the slate on the outer rim of the unopened can, and I support the base of the can at its center using a black diamond racing cone, away from the outer rim, so the outer rim never touches the shelf. The springiness comes from the flexing of the top of the can inside its stable outer structure. Someone gave me the black diamond racing cones, and I paid two dollars each for the cans of mandarin orange slices in water.

Mijo, I owned a Star Sapphire for 10 years, and I’ve had some experience with a Cosmos too. Based on my memory of these products only, I would have thought that the spring rate is certainly a bit higher than 3 Hz. In fact, I am now remembering that there was a modification to the springs that was performed by many owners, so as to reduce the spring rate. I can’t remember, but it had something to do with shimming the springs. Do you know anything about that?

Mijo, Re your response to Indra, how would you delivered energy to the equipment on an isolation device such that you could then “count” it’s resulting oscillations? Seems to me you’d want to replicate the natural state where hitting the TT with a hammer is irrelevant.

Yep. I do know what I am missing, and I don't miss it.Even when electronic manipulation of the system response is "transparent" (and I will believe that when I hear it), the subjective impression of the listeners I have been around is that they are not pleased with the SQ, compared to using no equalization on the very same system in the very same room.  Measurements do not coincide with the sense of verisimilitude that is after all what we are all ultimately seeking. I have attended several such demonstrations, and the net impression of other listeners and me is turn off the EQ. On the other hand, in your particular room with your particular equipment, etc, perhaps the results are different; I can hardly say otherwise. You can go your way, and I will go mine.  It would behoove you to recognize more often that you are expressing your opinion based on your own experiences, rather than to speak as if you are presenting the gospel.  This is not to say I don't advocate and implement room tuning to get the SQ I am after.  But I am sure that my room that satisfies me would not measure perfectly flat across the audible spectrum.

Every electronically-based room equalizer that I have ever heard does far more damage to the sound than it does good for the sound. So I agree with your strategy of altering the room, rather than the signal to give you your desired response at your listening seat.

I am waiting for someone to advocate some sort of springs for one's listening seat.  After all, if all the equipment is bouncing around, shouldn't the listener be moving in tune?
Indranilson, I would not be too anal about perfect level for your turntable, although it should be very close to level if not perfectly so.  But what is more important, if you are going to spring load it, is that the spring action moves the table in the vertical direction with perfect symmetry or near to it.  You don't want an external disturbance to cause one end or corner of the table to move more than any other.  In the extreme case, this could provoke a mechanical oscillation. Could also cause problems with tracking the LP.

Mijo, No argument here on the necessity for stabilizing an EM, but you previously intimated that this was necessary because of optical requirements.  Anyway, this is off topic, and I just wanted to be clear.  I used to have an EM, and a person to run it, as part of my lab. She wouldn't let anyone get even close to "her" machine.

Electron microscopes are electronic.At present there is no way to visualize biological molecules using only visible spectrum light microscopy, although there have lately been some tremendous advances in that science too.

I won't be mounting my Transmission Line woofer cabinets on springs any time soon or ever, thanks.  I do go along with getting any speaker up off the floor by at least a few inches if it's a tall full-range type (to de-couple from the floor, you don't necessarily need a springy or spongy support) or by the typical stand if it's a 2-way monitor, but none of that applies to either of my two systems, since both are large planar types, one ESL and one Beveridge which is not quite a typical ESL.

This concept of "zero stiffness" is interesting.  I have been reading the paper that was cited above.  It seems in fact to be a theoretical ideal rather than a truly attainable state. But that's OK as a guide. From my experience with turntable supports, the Minus K comes closest to zero stiffness.  If you can achieve what the Minus K achieves using only inexpensive commercially available springs or modified springs, you are a very patient person.  I would still have more than reservations about seating a speaker on a support that had zero stiffness, especially in the horizontal plane.

A good fraction of the energy that causes speaker cabinets to vibrate is coming from the back wave(s) of the drivers in the box, which is an issue separate from holding the drivers stable in position and a reason for the many ported speaker cabinets, which is an attempt to dissipate the sonic energy without exciting the cabinet.  I've always favored Transmission Line woofers, partly for the reason that such designs excite the cabinet very little, resulting in a very clean output.  The only woofers or subwoofers that I have successfully mated with my ESL speakers have been TL types. The cabinets of my home-made TL woofers that I use with Beveridge 2SW speakers are constructed of 1.25" thick HDF and weigh about 100 lbs each.  They don't move.  But given the fact they are TLs to begin with, they aren't very excitable, either.  Maybe this helps explain why I say that there are two separate issues with vibration and resonance.

First, I apologize to Millercarbon for my snotty tone in the context of my reply to his post about springs and such. I find myself in an irritable state of mind probably due to months of isolation and jitters related to the upcoming election. Only my wife can stand to be around me lately.
Second, I must say for the second time that "we" are confusing "vibration" with the pure problem of controlling the motion of a speaker cone. The box has to hold the body of the speaker stable so that the energy generated by the amplifier to move the cone is converted only into motion of the cone. This is never perfectly achieved, of course. My point was that if you put the box on springs or rubbery mounts, then you defeat the effort of the designer to hold the frame or body of the woofer stably in space, while the cone delivers its energy to the air. Instead, the whole assembly is now able to use up amplifier energy in motion that is opposite to the desired application of the force applied to it."Vibration" is certainly a resulting issue associated with the effort to maintain rigidity of the mount, but controlling or dissipating vibrational energy or resonance is after the fact. Do we know of any commercially available speakers that are supplied from the factory with springy or rubbery feet? I cannot think of one.

Picture a naked woofer hanging from a string or springs in mid-air and trying to reproduce a bass tone. Can you see that it would bounce back and forth in directions opposite to the excursions of the cone?

Miller, Stop trying to teach me physics. You can do whatever you like for whatever reason makes sense to you. I will persist in believing that putting speakers on springs or sorbothane pucks is NOT a good idea. "Vibrations" and their control is a subject for cabinet designers and the like. If you put the best cabinet in the world on springs, you will still magnify problems that are specifically due to the fact that for every action there is an equal and opposite reaction, in Newtonian mechanics. Moreso manifest in the bass region than in the treble, as Mijo says.

"Its not just the drivers going back and forth either."  But that was the only subject of my post.  You've gone off in a related but different direction.  Otherwise, why don't we just hang woofers and/or subwoofer cabinets in free air, from strings or springs? 

I'm not about to argue with whatever one wants to try putting under one's turntable, but I think there is a "logical" argument against putting springs or anything spongy (e.g., sorbothane) under speakers.  The amplifier is putting energy into the speaker drivers.  Ideally you want all that energy to be converted into the motion of the drivers, so as to capture the nuances of the music signal as much as that is possible.  If the speaker cabinet is sitting on a surface that can move, then inevitably (as in Newton's Third Law of motion) some of the energy of the signal delivered from the amplifier is converted into motion of the cabinet, rather than into motion of the driver cone.  That can't be a good thing.