[andyr]

What I'd like some people to do is compare the sound they get from their system after they've put their AKSA amp on an "air isolation platform" (which I'll define below) ... compared to the sound without it.  And then report back. 

Why I ask this is that I recently decided to put air isolation platforms underneath my two amp boxes.  You can see a box here:
http://www.audiocircle.com/index.php?action=gallery;area=browse;album=487&pos=11

This box contains my Maggie 3-way active XO and 3 AKSA LF modules ... and 4 power supplies.  The pic shows the box rests on a 20mm stone slab (offcuts from our kitchen renovation!  ) and this slab rests on the carpet ... which covers a ground-floor concrete slab.

An "air isolation platform" can be made by putting air bladders under a relatively heavy slab of stone or cement (like a garden paver).  Suitable air bladders can be:
* a partially inflated bicycle inner tube
* squash balls (which is what I used).

There is an optimum relationship between the weight of the slab + the amp, and the number of squash balls ... for a typical AKSA stereo amp and a 20mm slab of stone/concrete, I would recommend 12 squash balls.

What this arrangement theoretically does is isolate the amp from earth-borne vibrations.  Yes, I know it's hard to believe that there are such vibrations - and that they affect the sound - but all I can say is ... Wow!  What an improvement!! 

Now, given that I previously had my amps resting on a concrete slab - and some of you might have fancy isolating racks - if you do my experiment, you may well not notice any improvement.  But all I can say is ... listening to the excellent "Vocals Mix" CD which DSK gave me - which is a superbly recorded CD, BTW - every track seems to jump out at me with more dynamics! 

I won't try to explain why this might be - all I'll say is ... the squash balls ain't coming out any time soon! 

Hugh, Marty, Darren, Theo, Laurie and Lyn ... you're welcome to come round to see whether the sound now is better than the last time!   

Regards,

Andy

[manta]

Hi Andy

I recently auditioned a similar product found here

http://www.merlinaudiodesign.com.au/specials_folder/09_feb_xtra_specials.pdf

We demoed the sound difference between a CD player on the board and then just on the rack.
I noted a subtle improvement in sound stage and detail.

The board itself was a sandwich material with layers of foamy rubber (black in the pic). It sat on 4 squash balls siliconed to the base. I think you could make one cheaply for yourself.

[DSK]

Good stuff Andy 

About 6 years ago I went through a phase of being completely obsessive about platforms and footers, read hundreds of posts and articles on constrained layer damping, isolation vs coupling, etc etc. I made a variety of multi layer constrained layer damping platforms with different materials including foams, glues, bubble wrap, etc etc, used Media Isolation Bearings, Symposium Roller Balls, VibraPods, PolyCrystal cones, IKEA Lack tables, .... and the good old partially inflated bicycle tube. I also played around with mass loading on top of speakers and components.

In most cases the audible differences between footers/platforms were nil or slight but there were a few exceptions. I recall that I hated VibraPods under a tube CDP I had but loved them under a solid state pre-amp I had at the time. Many cones and spikes (under components) made them sound a bit bright and tizzy. The bicycle tube gave a slightly more relaxed sound but was a pain to maintain and looked crap. When I was using Symposium RollerBalls it was great fun to get non-audiophile guests to give the SACD player a light nudge then jump back in surprise when it started oscillating forward an back, left and right. I used 10kg leadshot bags on top of box speakers to great effect. They were very solidly built floorstanders that passed the knuckle test with no problems, yet the mass loading provided a more relaxed sound that allowed more inner detail and PRAT to come through. Mass loading on components had no effect on some and minimal effect (of the same type) on others.  Similar results were obtained by judicious placement of Dynamat Extreme inside component chassis.

Due to changes in equipment, trying to make things look better, and obtaining larger improvements from equipment mods and changes, I didn't feel the need to pursue this area further. My components now just sit in the wooden low profile cabinet, directly on the shelves (there is insufficient space above to use most footers or platforms anyway). Maybe one day, when I've completely finished with component changes and mods (like that's gonna happen  ) I'll revisit this area.

[LM]

Hi Andy,

Not being an engineer I have little knowledge of how best to manage air or ground based vibrations or how much they might or might not affect specific components but 'airbags' sure sound logical.  Personally, I sit my components on simple corK and rubber combo blocks - nothing as extensive as DSK has tried.

Regardless, my ears still work and any excuse to come and listen to your kit again and pass an opinion has got to be a good one.  Pretty busy next week or so but soon.

[andyr]

Hi Andy,

Not being an engineer I have little knowledge of how best to manage air or ground based vibrations or how much they might or might not affect specific components but 'airbags' sure sound logical.  Personally, I sit my components on simple corK and rubber combo blocks - nothing as extensive as DSK has tried.

Regardless, my ears still work and any excuse to come and listen to your kit again and pass an opinion has got to be a good one.  Pretty busy next week or so but soon.

Good-oh, Lyn.  Send me a PM when you can see you've got some available evenings/weekend afternoons. 

Yeah, it's hard to see what vibrations could affect an amp case sitting on a stone slab which is resting on carpet, on a ground floor slab ... which is why I never did this previously.  But, as I had a swag of squash balls lying around from a prior experiment, I thought "what the hell"! 

Regards,

Andy

[Sparkie]

Hi All,

Andy, you prompted me to get out a slab of foam rubber which I used for vibration isolation under the turntable. I placed the foam under the Surya which is sitting on the floor within a meter from the VSonics. The position for the Surya is not ideal and a permanent position for it has not been established as we often take it to our holiday house. The sound with the isolation foam seems to be fuller/more rounded and detailed. Likewise, I later isolated the CD player which appears to improve slam/attack of an instrument and particularly decay of a note which seems to be more delicate with as Andy says "a relaxed" sound..

A few days ago I had the Sorya sitting on top of an old boomy but powerfull sub woofer at the holiday house and the sound via a pair of AKsonics was not much better than a $200 mini "hi fi" amp. During a spring clean I repositioned the amp some distance away from the woofer, about a meter & a half away. That improved the sound dramatically and a very good articulate bass is produced. That said the AKsonic boxes are highly modified more to a  reflex style but with a resonator chamber around the inside of the port tube which nearly eliminates the inherent reflex sound. It was the magnetic field of the woofer driver that affected the amp. Lokewise the CD player doesn't like sitting on top of the amp on thhe woofer.

Good component isolation from vibration and magnetic fields works a treat.

I would like to hear your system again Andy. When I heard it a month or so ago I thought that it could not get much better.

Cheers,

Laurie.

[andyr]

Hi All,

Andy, you prompted me to get out a slab of foam rubber which I used for vibration isolation under the turntable. I placed the foam under the Surya which is sitting on the floor within a meter from the VSonics. The position for the Surya is not ideal and a permanent position for it has not been established as we often take it to our holiday house. The sound with the isolation foam seems to be fuller/more rounded and detailed.

I would like to hear your system again Andy. When I heard it a month or so ago I thought that it could not get much better.

Cheers,

Laurie.

Thanks for experimenting, Laurie.  Yes, more detailed was what I heard - with more dynamics. 

Delighted to have you round again (so you can tell me whether my system does sound better than before!). 

Lyn mentioned he'd be free in a coupla weeks ... would that suit?  6 ears is better than 2 for these kinds of things! 

Regards,

Andy

PS:  Foam rubber is, yes, a first step in terms of isolation ... but a heavy slab supported by an air cushion is better, IMO.  When you come round, I'll show you how I keep the squash balls fixed in place.

Regards,

Andy

[Sparkie]

Hi All,

Just had a talk with an aerospace engineer friend who specializes in electronic component interference. Quote. "All metal component boxes can and usually do have an unwanted influence on close by components. All iron based box metals do have magnetic fields. Such boxes are very good at restricting entry of outside signals. Metal boxes can due to vibrate and can reach harmonic points which generate unwanted signals which ultimately have some effect on the purity of signals. In a domestic scene where component compactness is not usually mandatory make sure that all components are well spaced and are isolated from vibrations. Even wrap all pcb's and motors in EFI insulating material to eliminate unwanted influences. Remember that component cooling should not be inhibited by a wrap in any way"

More food for thought and action???

Andy, I will be free for a listen in a few weeks.
Cheers,

Laurie.

[DSK]

...PS:  Foam rubber is, yes, a first step in terms of isolation ... but a heavy slab supported by an air cushion is better, IMO.  When you come round, I'll show you how I keep the squash balls fixed in place...

.. and then you get into another debate ... light & rigid vs. heavy & massive. The latter takes more vibration to induce resonance but once resonating it continues longer (a bit like inertia), whereas the light and rigid will resonate earlier but also stop much quicker, especially if well damped. But that's a whole 'nother discussion ...

Would love to drop around to hear your system again Andy ... still have to get you around here ...close now, just sorting out a few minor things...

[AKSA]

Shall we all make an evening/day of it?

Waddya say, Andy?  Can you handle it?

Hugh

[gerado]

Andy,

I had some bubble wrap, shaped in long tubes about a foot long and about as thick as a bicycle tube. This came in a sheet about a 2 feet wide.
I folded it in 2 and did put it under the GK, the LF and then the CD player. Cant say made any difference. However under my turn table it did find a home and thats were it stayed. Seemed to clean the sound up there.

Kyrill is always talking about the bad influences of metal enclosures and how wood is best, seems like there is merit in his argument.

Andy love to come but not in the next few weeks.

T

[andyr]

OK guys, I thought I might try to nail down a suitable time for y'all to come round and confirm my system does sound much better with the air-isolation platforms under my amps! 

Seriously - I'm a big boy and while I'm hoping to get confirmation that my ears are not deceiving me, if you guys can't hear any difference ... no sweat - we'll have had a pleasant listening experience!     (And I know it will be difficult to be sure, coz your last listen was quite a few weeks ago.)

So far we have Lyn, Laurie, Darren, Hugh & Theo who have indicated an interest - so how about Sat afternoon the 28th or Sun afternoon 29th March?  (Vicki is planning on being away at that time, which makes it very convenient.  )

And as well as some of the music we played last time, for direct comparison, given your recent epiphany with speaker placement, Hugh, I thought I would also play "Cowgirl" so you can tell me whether you can hear an uneven base line (I can't).    Hopefully, my new vinyl purchase "Lonely Hearts Dub Band" will also have arrived by then! 

Regards,

Andy

[AKSA]

Andy,

Thanks for setting up a group meet, 28th is out for me, Ben Williams is marrying that day in Sassafras, but 29th would suit?

Hugh

[andyr]

Andy,

Thanks for setting up a group meet, 28th is out for me, Ben Williams is marrying that day in Sassafras, but 29th would suit?

Hugh

Sun 29th is fine, Hugh.  (Now let's see if that's OK for the others.  )

Regards,

Andy

[kyrill]

hi, guys
Can you post a summary of the listening experience?
Or is it "just"  having some nice social fun?

[andyr]

hi, guys
Can you post a summary of the listening experience?
Or is it "just" having some nice social fun?

Kyrill, it's really just a concession to me so the guys who know my system can make a judgement as to whether the air isolation platforms which I recently put under my amps (see first post on this thread) actually do make an improvement. 

So about all that can be "reported" is "yes" or "no" from each person who attends. 

If you want comments from people about AKSA LFs and 3-way active Maggies, this thread has feedback from the last listening session:
http://www.audiocircle.com/index.php?topic=63258.40  (scroll down a bit)


Regards,

Andy

[gerado]

Hi Andy

Sunday nights are not good for me. I'm grounded pretty much on week ends with family activities.

T

[andyr]

Hi Andy

Sunday nights are not good for me. I'm grounded pretty much on week ends with family activities.

T

I was actually thinking of Sun afternoon from, say 1:30pm or 2pm ... but let's see how this time fares with the other people.

Regards,

Andy

[AKSA]

Andy,

1:30 suits me fine.  Theo, I'll pick you up!

Hugh

[andyr]

Andy,

1:30 suits me fine.  Theo, I'll pick you up!

Hugh

Hi Hugh,

As I understand it, Theo was saying that weekends are out for him.

Regards,

Andy