„PAB anti-vibration platforms are used for placing audio and (or) video components on them, to isolate them from external vibration; thus minimizing resonances resulting from imposition of those on intrinsic vibration of electronic devices. Very good anti-resonance characteristics of those platforms come from the way the shelf, on which the equipment is placed, is suspended. This suspension is made in such a way, that there is only minimal contact with the environment (the shelf is suspended on four cables going through four pulleys and anchored in tension mechanisms).
However, we also found out, that there are some other things, that have a positive impact on those characteristics:

• Materials for the construction of the shelves and plinths (mostly birch and alder plywood, covered with natural veneers; to a lesser extent MDF and particle boards with synthetic veneer);
• Materials for the mechanisms, that keep the shelf horizontally suspended above the plinth (brass, non-magnetic steel, nylon and rubber);
• Tensioners, allowing to level the shelf and position it on a specific level (note: the platforms supplied to the users have the shelves leveled at the lowest possible level, however the muffs for the tensors have a length of a few centimeters, what allows to rise the shelf significantly and adjust the sonic capabilities of the platform to the needs of the equipment used and personal taste).”

(source – materials on the PAB web page)

This is all true. I met with Mr. Władysław Skrzypczak some time ago, when he brought me a platform destined to be tested in “Audio” (that test appeared in the issue 9/2010). Because at the same time I tested also other platforms, including the very expensive Harmonix RS15-ANV, supported by the TU-666ZX feet as a reference, I had the opportunity to compare many different solutions and philosophies behind such products. Two of those seemed very similar to me – Pro Audio Bono and String Suspension Concept Base Classic. And it was no coincidence. After talking to Mr. Władysław, it turned out, that bases from SSC gave him the impulse to work on his own solution. After longer contact with both solutions I must say, that the Polish one seems better conceived, has better craftsmanship, and is just plain better. SSC was still very good, it is a simple, but very efficient idea. But I chose PAB for myself.

PAB platforms base on decoupling two shelves – the top one, on which we place the device, and the lower one, a plinth to which the upper is mounted. Important is the fact, that both those shelves are mechanically decoupled – here by means of nylon strings, on which the upper platform is hung. This idea is known from turntables, most notably the models SME 20 and SME30 from SME Limited. In their construction we also have two platforms, but decoupled by means of many rubber rings. The idea behind their mounting is exactly the same as in PAB – to the lower plinths some kind of pillars are mounted – metal pipes, reaching a few centimeters above the surface of the top shelf, with which they have no contact. On top of the pillars there are the rings (SME) or “strings” (PAB), on which the shelf is mounted. And that is it. In the Polish platforms it is a bit more complicated, but not by much. The “strings” are made from nylon, a material chosen from a few dozen of tested materials. They needed to be strong, have good damping characteristics and could not elongate in time. They are not mounted to the supports permanently, but by means of a pulley, going back to the lower plinth to the tensioning mechanism. This tensioner is made from a mechanism used in string instruments to apply tension to the strings. The whole platform needs to be leveled, and then strung in such a way, that the upper shelf is floating as low as possible over the plinth, while not touching it. Tensioning should be done without the load placed on the platform! Otherwise the string will be over strung and will lose its capabilities. This means, that we need to make the adjustments with trial and error. But in fact it does not require much time to do it right. The mechanical properties of such a setup, for example its resonance frequency, the way it damps vibration coming from outside or from the device placed on it will be defined by the parameters quoted by Mr. Skrzypczak in the fragment I placed in the beginning of this test. I would add to them the thickness of the shelves and the length of the strings, on which it is supported. And the weight of the device placed on it, as well as its mechanical setup. So we need to take many elements into consideration, but this is just how it is.

Because this time I wanted to test the influence of the shelves on the sound in my own system, thinking about my own devices, I ordered a platform with the dimensions suitable for my Ancient Audio Air player. But to complicate the issue, and to have a reference point, I asked Mr. Skrzypczak to send me another platform, with exactly the same dimensions, but with the shelves made from plywood with double thickness (also birch plywood). This other platform had golden feet. In this platform the tensioning mechanism could be placed inside the plinth, with only the pins sticking out, which are operated by a small crank. On a classic platform a device with a mass of 48kg can be placed, the double thick one accepts 60kg units.

SOUND

Discs I used while testing:

• Stereo Sound Reference Record. Jazz&Vocal, Stereo Sound, SSRR4, SACD/CD.
• Ann Richards, Ann, Man!, ATCO/Atlantic Records/Warner Music Japan, WPCR-25181, CD.
• Artur Lesicki Acoustic Harmony, Stone And Ashes, Fonografika, 559040, CD + master CD-R; review HERE.
• Gerry Mulligan Quartet, Dragonfly, Telarc, CD-83377, CD.
• Jim Hall, Live!, Horizon/A&M Records/Universal Music Japan, UCCM-9225, CD.
• Mikołaj Bugajak, Strange Sounds and Inconceivable Deeds, Nowe Nagrania 001, LP+CD+WAV 24/44,1.
• Miles Davis, Seven Steps To Heaven, Columbia/Analogue Productions, CAPJ 8851 SA, SACD/CD.
• Nat “King” Cole, Love is the Thing, Capitol/Analogue Productions, CAPP 824 SA, SACD/CD.
• Savage, Tonight, Extravaganza Publishing Srl/Klub80, CD001, 25th Anniversary Limited Edition, CD; review HERE.
• Suzanne Vega, Close-Up. Vol 1, Love Songs, Amanuensis Productions/Cooking Vinyl, COOKCD521, CD.
• Youn Sun Nah, Same Girl, HUB Music/ACT Music + Vision, ACT 9024-2, CD.

Japanese versions of the discs available on CD Japan.

The most important element in the sound of each audio system is the midrange. This is a mantra repeated over and over by the British, partially to cover-up for the requirements posed by their living rooms, where large speakers would not have any place, and partially supported by the BBC experience, which is the same for the British as for us the… Well, in fact we do not have something similar. Anyway – midrange rulez, is the best and so on. Like I say, this is not about any technical or psychoacoustic truths, but about a certain quibble, which legitimized the sales of small form loudspeakers, which do not have any bass, and usually had a bad treble (now this has changed). There is a lot of truth in that, but only when looked at from a certain angle.

The midrange, let’s say around 1kHz, is the area of the sound spectrum, where the human hearing is especially sensitive, what means we perceive any, even small distortion, phase changes, departures from tonal balance, etc, in a much stronger and direct way, I would say a “natural” one, than the same problems on the top or bottom of the sound spectrum. This is a good reason to fight for the best possible emission of the human voice (because this is what the whole evolution was about). But it is so, that the British “fight for the midrange” had less in common with a natural sound as we might think. Research, but also my experience, shows, that to reproduce the human voice well, we need a very wide frequency response – a change on the lower octave in the cut-off point from 30 to 50Hz shows the voice completely different. Experiments made during audio shows by the magazine “Hi-Fi+”, which added a good quality subwoofer supporting the loudspeakers from 20 to 30Hz allowed to show the music in a completely different way. The same thing happened when adding a super tweeter to wide band loudspeakers – it added to the clarity of the bass and at the same time the naturalness of the midrange.

But let us get to the point of the test – this long introduction was needed to be able to see what PAB gives to the sound from the right perspective. The change of the sound when placing the Air player on it is evident. And it did not have to happen – the player is supported on very good feet finite elemente CeraBall, and the whole on a very rigid shelf Base. By placing the player on the PAB platform most improvement is in the midrange. It becomes fuller, more saturated and warmer. But not by changing the tonal balance. And this is the reason I needed the introduction – in fact the changes are in the sound of the treble, now smoother, fuller and deeper and the bass – stronger, but not as contoured. I perceived the change in a totally positive way. Better treble and bass combined in what I told before – better midrange. On itself it could have been perceived as becoming warmer, if not for the fact, that I heard this effect many times, and it was always related to lower distortion, more peace in the sound and darker background, as if there would be less noise everywhere. This is of course only a description, this cannot be classified unanimously, but only in such an indirect way we can show what has changed.

In general with the platform everything was more mature, less hi-fi and more natural. Switching to the marble shelf the sound lost freshness and slightly “collapsed”. In itself. It was not an implosion, the changes did not blow the head off, but they hurt me. This was especially painful, because when Mr. Skrzypczak sent the platforms, I placed the thicker under the player, the thinner under the amplifier Leben CS-300 X (Custom Version) and forgot about them for two months – they were just there, and I did not notice them, perceiving the sound of my system as something given and natural.

So taking the devices off the shelves was a big pain. As you can see there is no speaking about accustoming oneself to the sound during a test, because first I got accustomed to the new sound, I change my way of perception in such a way, that the platforms “disappeared” from the equation. Moving them away instantly allowed me to show the elements I was talking about. Most pronounced were the changes with the disc of Suzanne Vega Close-Up. Vol 1, Love Songs, where there is mostly a strong, full voice and a guitar, sometimes supported by other guitars. Without the platform the sound was more dim, somewhat collapsed and it moved me less. And I must say that earlier, before the platforms came, I did not miss anything, I though the sound is really OK. Interestingly without the shelves supporting the player, the reverbs accompanying the sounds could have been heard better, especially on the piece Caramel. The vocals is recorded in a different way than for example on Small Blue Thing. Worse, with too much reverb, and setting on the reverb device the distance of the voice to the stage further than necessary (for example in the Lexicon reverb unit, there is a slider for virtually moving the sound source in the space, moving it forward and back, without making it quieter). So the sound is more withdrawn, and not as direct as on other recordings from that disc. Without the platform, the reverb, long and low, was heard better. Unfortunately this time the voice was too distant, as if something would cover it up. I have the idea, that this was caused by less pronounced lower midrange and treble, which was less resolving.

And resolution is probably what all this is about. But it is not resolution in itself, detached from music. How well this was shown by the disc Ann Richards Ann, Man!. Suzanne Vega disc is slightly warm on itself, and has a limited instrumentation, so not everything is clear from the very beginning. The effect is the same on each disc, but with Ann, with a very well recorded disc, we just get there quicker. With the platform, the sound almost “exploded” from the loudspeakers, as if someone heated it up. It was still all about a slight warming, but it was not giving the tone to everything, but better shaping of the instruments and better dynamics were. I got used to such sound, that I forgot, it can sound differently. I mean, I know it can sound different, I use the Richards disc for testing for some time, and each change of amplifier, player, loudspeakers, etc, resulted in a different sound. And the platform does not change the sound as a change of an element in the sound chain does. And this does not mean, that the change is smaller. Or bigger – because it is different. In general the character of the sound is kept. And I would not count on any improvement, if we have not a good system, with something wrong in it. It can help cover the flaw up, because it will diminish the background noise, emphasize a little the sustain, what will improve its juiciness and warmth. But those will only be half-measures. In a good system PAB will emphsize its good sides, not having to cover anything up.

Listening with the thinner shelves was equally instructive. The sound was slightly lighter, it did not have such a saturated lower midrange. At the same time treble was shown stronger – but not bright, not dry, just juicy and strong. Maybe this got lost with the shelf twice as thick. Not that I complain – it was superb. But the listening session with the other platform showed, that it can be developed more, we can achieve more. The change of the thickness allows to adjust the shelf to our system. When we think, that it needs cleaning of the sound, but without drying it, we should decide for the thinner shelves. The sound will be clear, resolved, strong, and will not be enlarged. But if we need to put some weight on it, enlarging the virtual sources, etc, then the thicker shelves will fare better.
For my system the thicker platform seems more fitting. For me the way the voices are shown is priceless. I think it is about the whole frequency spectrum, that it improves the top and bottom ranges, but those improvements, those corrections are translated into a more natural midrange, to the voices having more volume, being deeper and stronger. Many times they sound better than during a live performance, better than I know them from an opera or club. How is this possible? Well – audio at home is a kind of “theatrum”, showing only the best things from the performance on the stage. Without the problems of a concert hall acoustics, without problems coming from the placement of our seat in the audience and with the best (that will of course depend on what we purchase) performances. Yes, I want to listen to that.
And Pro Audio Bono has a splendid product. We can already treat it as a finished product. Although some things can be improved here and there, and I will cheer Mr. Skrzypczak on that.