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In Reply to: Sound of CD player with different isolation mechanisms. posted by SoftwireEngineer on August 11, 2003 at 14:33:50:
First off dont let anyone in the other forums here tell you its all in your head, its real. I mass loaded my dv47a with 15lbs of granite and put a vibrapod under each footer the sound was so much smoother in the highs,imaging and bass tightened up. But I wasnt prepared for the effect the pods had under my center channel speaker. My center sits ontop of a 55" Mitsub diamond vision TV and after isolation it was incredibly liquid and clear. Since then I isolated my pre and surround amp with the pods and my 2ch amp with molly toes (It didnt respond to the pods as well as the mollys). Also if your fronts arnt spiked definatly try doing that. FYI. I would forget the bike tubes and bubble wrap and spend the six bucks to the pods or mollys, get them at needledoctor.com
Follow Ups:
Exactly..I had the same feeling..I thought isolations will change the sound a little bit..but I could clearly see a difference between different mechanism and the difference is really stark.I think the VibraPod technique is similar to the bicycle tube but more elegant. I will order that next. My Int. Amp is already on three feet (Audio Refinement Complete). But I am going to get some nice spikes for my rack and put something heavy in each shelf (like granite or marble slab).
Hi SoftwireEngineer,"I think the VibraPod technique is similar to the bicycle tube but more elegant."
"Elegant" perhaps but a well implemented bicycle tube will be more effective.
Two things to keep in mind with inner tubes:
1. Inflate only enough to achieve air support. One pump too much and the resonance is too high and the benefits go away.
2. The larger the circle described by the diameter of the inner tube, the easier it is to balance gear atop it.The only thing I'd add is that the combination of an air bearing with roller bearings will result in your player being "freed" to perform its best. It will sound like all your CDs have been remastered (at a higher level of Quality).
You might want to check out the link below.
Happy Listening!
Barry
I've experimented off and on with inner tubes and am curious what air pressures others use. I have found when the tube appears to have the proper pressure the stiffness of the valve stem and attaching skirt interfere with the buoyancy of the apparatus. Adding enough air to remedy this problem makes the tube too stiff IMO. You all doing things differently?I suppose it would fairly easy with the use of tube repair kits to fashion a remote valve away from the component, is that what you're doing?
Hi Hafdef,I haven't experienced the valve stem interference you describe. Maybe this has something to do with the inner tube design (?). I've had success with tubes I purchased from bicycletubes.com (see link below).
Happy Listening!
Barry
Two things to keep in mind with inner tubes:
1. Inflate only enough to achieve air support. One pump too much and the resonance is too high and the benefits go away.
2. The larger the circle described by the diameter of the inner tube, the easier it is to balance gear atop it.Barry - sounds like you've experimented with the pump quite a bit.
question:
"achieve air support" - does that mean the moment the load is suspended above the below surface by air, with the inner tube still nearly flat on the ground?
I have an inner tube under my CD player, separated by a board of MDF over the tube, then two large paving stones on top of that, then the roller bearings and the CD player on top of that. Is mass loading the inner tube the way to go? I think it is, but that's just based on my own assumptions that it would be harder for vibrations to excite that heavy load on top of the tube than for the rack to do the same if the heavy stones were on the rack below the tube.
So in short - is mass-loading the inner tube the way to go? I tried mass loading my CD player with a 5 lbs bag of fine sand on top of the roller bearings, and that was definitely NOT the way to go.
Second scenario in my sytem:
I wonder if there is a limit when the mass gets too high, and the pressure in the inner tube becomes too high to still isolate the above items effectively, simply because it needs to be pumped up very hard to support the load? I have my mono amps on platforms (spikes below 2.5" of maple board sandwich, then 16" inner tubes, on top of that 2" thick 18x18" paving stones, on top of that 60lbs amp resting on factory installed vibrapods). There's at least 100 lbs on the inner tube, and it gets rather flat even with a few good pumps of air into it. I don't really need the heavy stone under the amps unless I go to roller bearings, and even then I could probably get by with a lighter mdf platform on top of the inner tube. Since the amps are right behind the speakers, there's still ample vibration in the rather thick (1/4" aluminum) amp cases, even though there is damping material on some of the inside surfaces. Perhaps you just can't win the isolation game by putting your amps right behind the source of vibration, especially like in my case when it's a planar speaker sending a full back wave of audio in that direction?
I'd have the amps on roller bearings if I culd come up with a cost effective "cup" that will actually support the weight. Still looking.
Peter
Hi Peter,""achieve air support" - does that mean the moment the load is suspended above the below surface by air, with the inner tube still nearly flat on the ground?"
Yes. You want the tube as loose and floppy as possible but the component to be supported by air (as opposed to sitting directly on the tube compressed under the component's weight). When I've heard complaints about using air bearings (loss of "air" or sloppy bass), they've invariably been from folks who over-inflated the tubes.
"Is mass loading the inner tube the way to go? I think it is, but that's just based on my own assumptions that it would be harder for vibrations to excite that heavy load on top of the tube than for the rack to do the same if the heavy stones were on the rack below the tube."I haven't yet heard any particular advantage to mass loading. I don't believe this makes it "harder for vibrations to excite" the load, it just changes the frequency of the vibrations that can excite the load, perhaps making the load more sensitive to the lowest, most sonically damaging vibrations.
"I wonder if there is a limit when the mass gets too high, and the pressure in the inner tube becomes too high to still isolate the above items effectively, simply because it needs to be pumped up very hard to support the load?"The amount of air necessary to achieve "air support" will vary with the load. In other words, achieving an optimal, very low resonance will require much more air when supporting a heavy power amp than when supporting a light CD player. In other words, under the amp, more "pumps" are required to achieve the same resonance as the CD player with fewer "pumps".
As far as the speaker back wave exciting the amps, I'd try:
Placing the inner tubes directly on the floor, topped with thick (1"?) ply (not MDF), then roller bearings, then the amps. If you're going to use inner tubes without roller bearings, I'd go tubes, platform, then amps. In my opinion, the spikes, paving stones and Vibrapods might be working against you in this case.
Hope some of this helps. Also, please post what you hear as you experiment further.Happy Listening!
Barry
Peter,The tube acts like a spring with its own resonant frequency. You want that frequency to be as low as possible.
The easiest way to get a handle on the frequency is to lightly push the component on top of the tube and see how fast it rocks. The more the tube is inflated, the faster the component will rock. You want it to rock back and forwards slowly, only 2 or 3 times a second at most.
How much air will be required in the tube to achieve this will vary depending on the mass of the component. Heavier components will require more air.
I would NOT use Vibrapods with a tube system. They are both 'springs' and I have never been able to achieve the best result using 2 different springs in an isolation setup. I also don't like adding lots of mass, especially below the spring. High mass bases resonate at low frequencies and spring systems actually transmit and magnify vibrations at frequencies lower than 1.4 times their resonant frequency. You may actually end up creating a low frequency vibration source that the inner tube can't deal with and may actually magnify. I'd go for a much lower weight but very rigid base for the tube. An inch thick layer of ply or MDF, perhaps with aluminium sheet on both sides of it, would be preferable to the pavers and granite in my view and I would use spikes or cones beneath it to couple it to the floor. The tube, properly set up, should work more effectively on a much lighter bass actually coupled to the floor.
David Aiken
the problem with lowering the weight is that soon there will be a stack of two mono blocks, with the amps alone weighing in at 120lbs on each speaker side.The tube is on a very rigid maple ply sandwich (3x 3/4" screwed and glued together), so that should be ok.
I'll drop the paving stone and put something light under it, but I can't dump the vibrapods quite yet, since I have no roller bearing dishes that will handle even a single amp. Perhaps I need to move the amps off the platform, which is what my speakers are sitting on as well, but I don't have enough room anywhere near the speakers to put them, plus I want to keep the wires as short as possible. I have to think about the entire structure some more, and possibly replace it with a thin and rigid metal stand.
the other thing - things are currently sounding better than ever before in my system, so I don't think there's anything inherently flawed with the current amp stands. However, since I have not tried a very different approach yet, I am exploring the ideas here in the forum first. Tomorrow I'll place some mdf on the tube and see if I can get rid off the vibrapods easil. Heck, before that, I'll just place the amps on the ply platfrom without inner tube and paving stone just to see what vibrapods alone can do. If my setup amplifies problems, then this should sound better, right?
Peter
I read your setup description wrongly and thought the mass of the amps was part of the mass below the inner tube.OK - things are reasonably light below the inner tube because there's only maple there.
Above the tube, the mass is really the 2 cement pavers.
What I'd recommend for you to compare is the amps on their Vibrapods on top of the maple (remove the tubes and pavers) against just replacing the pavers with a second piece of the maple ply. I think that either should sound better than with the slabs, though I'd bet on replacing the pavers with another piece of maple and retaining the inner tube sounding best provided you get the air pressure right.
I hadn't picked up on your point that the Vibrapods were factory installed. If you can find some fairly stiff feet or cones that are taller than the Vibrapods, I'd try both the options above with the Vibrapods effectively 'bypassed' - just slip the replacement feet or cones under the amp chassis to raise the amp off the Vibrapods. My feeling is that bypassing the Vibrapods in both cases will sound better than the same option with the Vibrapods.
You say the speakers are on the same platform. That's the maple ply, right? So I'm guessing it is a fair bit larger than the speaker base and there's an area behind or beside the speaker on which the inner tube sits with the amps above that. I think you'd get better results with amp on a separate base but if the tube is set up right, the difference should be slight. I wouldn't worry about that until down the track after you've sorted out differences from the other changes. If you decide to put them on separate platforms, you can cut each maple ply base into 2, leaving the speakers supported as they currently are and using the cut off piece as a base for the inner tube.
David Aiken
I tried the amps just on the maple, vibrapods, nothing else. Very similar sound, but I have a hunch there's a little less bass now.Next I'll move them on the tube, with MDF in between.
CAn't cut the maple base into two - the whole point of it was the rear bracing of the Maggies, and the bottom rear of the platform is where the rear panel braces connect to the base. The amps sit right in between. Theoretically, I could cut a hole into the center of the platform to separate the base the amps sit on from the speaker support structure, but I better know exactly that this is the way to go when I do this. I may just switch to a custom steel stand for the speakers, which will free up the floor behind the panels for a dedicated amp support stand.
Lots of stuff to think about.
Peter
One of the first things that happens when people start to experiment with isolation is that the bass changes and people start having problems with the change.The first thing I would say is that you're very used to the bass presentation that you've had and your immediate response is always a comparison, hence your comment that you suspect there is a "little less bass" now. Often there's an implicit assumption here that 'more is better' and that when a change results in 'less' of something, then it is a step in the wrong direction.
Leave things as they are for a few days and keep listening until you get used to the new bass presentation before you make a final judgement. My experience is that a lot of the times, the 'loss' of bass is due to the reduction of some emphasis in the mid to upper bass range and that what comes with that is greater extension with a bit more becoming audible in the lower bass, and often an improvement in the definition and tone of the bass as it firms or 'tightens' up. We all have different takes on which of those 3 factors - quantity, extension and definition/tonality - is more important to us and which is least. In the long run I seem to have gravitated towards appreciating the extension and definition, and I'm usually quite happy to sacrifice a little weight for a bit of gain in the other 2 areas. Your preference may be different and there's nothing wrong with that. We probably prefer different coffee too :-)
Also, while bass is often the first thing noticed, it won't be the only change. There will be changes everywhere, including in soundstage and imaging, in the overall 'noise floor' and the sense of greater or less 'silence' or 'blackness' between notes, clarity and definition of sound, dynamics, and tonal colour. Trying to sort things out can be quite difficult at times.
My rule of thumb after playing with isolation and room acoustics for quite some time is quite simple. The really good and genuine improvements all tend to do 2 things in common, even though other things may be more apparent at times. Those 2 things are an improvement in clarity and an increase in tonal colour which is associated with a greater sense of difference between instruments and voices. Things just become more 'colourful' in a sense, though without exaggeration. Try putting on a percussion disc and just listening to the different tonal colours associated with drums of different sizes, skin tensions and striking techniques. Yes, it may sound punchier and more dynamic, and go deeper or have more weight, but if you aren't able to better distinguish the differences between the individual instruments, or between voices in a vocal group, then the change may be accentuating one factor in which case you may end up tiring of it eventually, however enticing it is at first. There tends to be a hidden cost when one thing is accentuated, and it can take some time to find it, but it may be a cost you ultimately aren't prepared to pay. In my experience the genuine improvements don't carry such costs.
David Aiken
We should evaluate the changes holistically, not how it increases the bass or highs or soundstage. The sound should get more 'realistic'. You are right about the changes being more 'colorful'. In my case, my player is also a DVD player (963sa) the pictures are now more 'colorful' literally. I have watched the Dinosaur DVD umpteen times (my 2yr old son watches it all the time) now suddenly I can see the light purple tinges to the meteor shower. Whenever the dinosaur or monkeys move abruptly in a closeup shot, it feels as though they would pop out of the screen.
(BTW, I cannot put Dynamat on my player because it gets too hot on the outside, that is why I use coins in a foil wrap for damping. I might stick the Dynamat to the underside of my shelves though).
IN my case I am fighting an inherent lack of low freq extension and impact. We're talking Magnepan 3.5R without subwoofers.I've been finding more and more with isolation, rear panel support, etc - none of which I would consider "too much" or "undefined"
removing the tubes and paving bricks has not been a big change in bass, and I am still listening to the plain vanilla "amps with stock vibrapods on maple platform" setup right now. I may go back to the previous setup just for a 2 way comparison again after I am used to the new sound.
After that I plan to do the tube/mdf/DIY roller bearings (instead of the double spring vibrapods).
Need to find 6 chromed basting spoons again so I can get the amps on the ball bearings :)
I'll be going through my bass-relevant test CDs tonight to see where things stand after 2 days just on the maple.
Peter
Gaining extension is a strange process in a couple of ways. For a start, as I said above, it usually comes at the cost of some bass 'quantity' a bit higher up. Educating yourself to appreciate a flatter response takes a bit of time but does yield a lot more enjoyment when you no longer miss the weight a bit higher up in the frequency range. It's also strange when you start to notice just what can gain you a bit more extension.Vibration control definitely helps. My experience is that getting stands as rigid as possible and applying any isolation immediately below a component is best. What is surprising is just where the vibration can get it, and even cables seem to be able to transmit vibration. Try raising speaker cables off the floor with raisers of some kind, and keep your interconnects to the amps, and even the amp power cords raised. You may not notice some of these things initially but they can add up, and as you start to reduce overall vibration levels affecting your system you will start to notice things where you didn't notice anything before. Be prepared to look at everything in your system as a potential source of vibration.
Cable hygiene is important for other reasons. Run power close to other cables and the electromagnetic field from the power cord can modulate the signal in the other cables. This can be another source of premature bass roll off.
Room acoustics, especially absorption and the reduction in room reverberation time, will also gain you some extension. It lowers the 'noise floor' of the room, allowing you to hear some lower bass that was previously masked by the reverberation. This also gives you a better sense of dynamics and a lot of other goodies as well.
And finally there's power. Bass response is always more demanding on amps, regardless of whether we're discussing extension or quantity or both. If you can use a dedicated line for the audio equipment you may well be surprised at the results. Good shielded power cords and a bit of power filtration can help a lot also.
None of these will turn your Maggies, or my Dyn Contour 1.3 SEs into speakers that shake your chest at 20 Hz, but I think you will be surprised at just what paying attention to a pile of little things can do to imporve your sound overall, including gaining a bit of bass extension you never dreamed your speakers were capable of. I'm convinced very very few people ever hear what their speakers, and system, are really capable of. Putting in the care and attention to the little details needn't cost a lot and it certainly can and will yield quite significant improvements. I can virtually guarantee your system will surprise you, no matter how well you think you know its sound.
David Aiken
"Gaining extension is a strange process in a couple of ways. For a start, as I said above, it usually comes at the cost of some bass 'quantity' a bit higher up."that all depends on where you are starting. I started with a 1980 receiver (big, but still 1980), powering maggies standing on carpet, 2 feet off the wall, CD player resting on top of a tape deck on top of a shaky metal shelf, with $10 speaker wires and $10 interconnects.
when you work your way from that setup to what I have now, you gain extension and quantity, to an extent that it can blow people away who heard the speakers a year ago in that configuration and concluded maggies have no bass, to what I have now, where you can sense the bass even at low volumes, while it is tighly defined.
I have changed everything but the raw CD player mechanism and the speakers in that year, so mow I may be in the arena you are talking about, where things are already mighty good, but it gets harder to tell if it's a step ahead or back when you make a change. However, I remember making changes that simply blew my mind in terms of what it did to the bass presentation in my system, such as moving the speakers far off the wall and putting very powerfull amps into service. There was for example the realization one day that my speakers were not "damaged" because I heard a massive distortion on certain CDs that went to deep bass, but that it was a problem with the CD player isolation and lack of amplifier performance.
" Try raising speaker cables off the floor with raisers "
my speaker cables are unable to even reach the floor - they are 11" and need to be tightly bent to reach from amp output to maggie input. Not an issue. ICs are short and well supported.
"Cable hygiene is important for other reasons. Run power close to other cables and the electromagnetic field from the power cord can modulate the signal in the other cables. This can be another source of premature bass roll off."
regarding power cables - they go to the back of the rack and are short, RCA goes out the front to almost mid room where the speakers and amps sit. there's enough power isolation conditioning and filtering on the CD player and analog cicuits, I could just as well run those things on batteries. Power amps go straight into the wall, dedicated circuit for the room where there's nothing else powerd up when I listen.
Thigns are pretty clean, and when I change from putting an inner tube under a paving brick under my amps to amps on vibrapods alone, the change is very minimal (nothing like an amp upgrade or pre-amp tweak). It's actually very hard for me to hear any difference at that stage, and I don't think my ears are good enough to actually be able to tell what happened. I simply will follow what "I like" to hear, since that's what matters. I have certain ideas of what I like in my bass and it may or may not be what some sort of amp isolation method accomplishes. I just keep trying out different modes, and when I find what I like, just like with my CD player setup, I move on to other things. Right now I just haven't tried out enough approaches to isolate the amps. It's a challenge, since we're dealing with heavy amps, and soon a stack of two heavy amps on each channel. It has to be mechanically sound beyond simply sounding good. I don't want 120 pounds of amp to roll off some roller bearings just because the inner tube below everything leans over a little too much.
I will sacrifice some sound quality for the peace of mind that the amps won't roll off the platform when I vacuum behind the speakers or the kids play hide in seek between my cables ;-)
But if it was easy and there was one perfect solution, this woudn't be as much fun as it is, right?
Peter
I agree!Timbo
--SF
Hi Barry,I have an amp that I put in a Par-Metal 2U style metal chassis (www.par-metal.com). I want to try using a bike inner tube, but do I really need a piece of ply wood on top of the tube? I ask this because the bottom of my amp chassis is all flat, so it should be able to rest on the tube without the ply wood. Plus, maybe the ply wood adds different resonant effects?
Thanks for your info!
Vinnie
Hi Vinnie,"...do I really need a piece of ply wood on top of the tube? I ask this because the bottom of my amp chassis is all flat, so it should be able to rest on the tube without the ply wood. Plus, maybe the ply wood adds different resonant effects?
I use the plywood to support my Hip Joints © roller bearings, which I'm using in conjunction with the inner tube air bearing. I find the 1" maple ply to be less damaging to the sonics than MDF or other materials I've tried so far. (My setup is shelf/inner tube/plywood "platform"/Hip Joints © /component.)
If you're using an air bearing without roller bearings, give it a try and see. As David said: "The inner tube resting against the chassis will damp vibration in the chassis itself to a degree...". One consideration though, might be heat from the amp. Wouldn't want the bottom of the chassis marred by residue from the inner tube.
If you try any of this, please post what you hear.
Happy Listening!
Barry
Vertically isolated by the tube and horizontally by the Hip Joints. Till I get an Aurios MIB or Daruma or any such device, my CD player will be directly on the inner tube. Placing it directly on the tube, I feel is good when the chasis is not that heavy/strong, draining away some chasis vibrations. My mass loading is not that heavy, probaly a pound or two of coins wrapped in aluminum foil and laid flat in the center on top.
With a light weight chassis, you may find the tube damps it sufficiently without added weight on top. If it doesn't I'd consider adding a couple of strips of Dynamat instead of the mass.As a somewhat bizarre suggestion, if your chassis is steel rather than aluminium then try replacing the coins with some of the soft rubber type fridge magnets that everyone has. Place them to cover a bit over half the distance from the left to the right side of the chassis and make sure they are placed a quarter of the way from the front to the back of the chassis. The chassis needs to be made of a material the magnets will stick to for this to work.
David Aiken
Try it. The inner tube resting against the chassis will damp vibration in the chassis itself to a degree as well as isolating the amp from floor borne vibration. The damping will also change the sound. You may actually prefer the sound with a ply or mdf slab on top of the tube, and the amp sitting on the slab with or without feet.David Aiken
Hello, Recently i did replace the seismic sink under my Rega Jupiter transport by Black diamond racing cones. So far they aren't attached firmly to it. It rest on a very sturdy wall attached frame. The plinth is made out of mixture of stainless steel , ordinary steel, brass, aluminium, lead, wood, vinyl. Most of the layers are joined by a bituminous product to repair roofs. The whole is more sensitive to feedback because when i hit the plinth, the cd will skip. But the sound is much more analogue then before. Maybe if the cones are glued it will be less sensitive and i can massload the transport with lead or sand. Maybe there is a lot of room inside the player that can also be filled. You can see that nothing is sacred and there isn't a solution that will give an upgrade in every situation. Ed
I agree that there is no universal solution. Personal taste guarantees that since we all like a different sound presentation. I like things light and rigid, but I don't use inner tubes or air platforms. Never had much luck getting things balanced and the air pressure right with the inner tubes.David Aiken
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