The sound of chassis?

[Peter Daniel]

Here's what Shannon Dickson of Stereophile says about pneumatic platform. After trying it myself, I have to agree with every word he says:

" In fact, it was the rather dramatic experience of hearing the sonic effects of pneumatically isolating a turntable and---surprisingly---a digital transport with the Vibraplane that led to this report, lest the relative sonic impact of these systems be confused with that afforded by more traditional means of equipment support.

Before floating my source components with the Vibraplane, I was, like many of you, intimately familiar with the array of tonal changes afforded by various tuning devices. But by the time the stylus of my Lyra DaCapo cartridge had reached the inner groove of the first record played on my RPM-2 turntable after a Vibraplane had been installed beneath it, I had experienced a pronounced enhancement in the broadband resolution of my system that was very different in degree and quality from that offered by tonal manipulation alone. These benefits were turned out to be both predictable and repeatable with a variety of source components.

I rank an even, natural tonal balance---with the emphasis on balance---as one of the most critical factors in true high-end performance. (This is to be distinguished from simply highlighting one area of the spectrum over another just because it sounds "better.")

But I'm not anti-tweak. Creative experimentation has often led to real breakthroughs, even when the relationships of cause and effect are not well understood. Tonal alterations that make listening to a given system more enjoyable are perfectly fine in my book as long as the effect is not mistaken for, or promoted as, a de facto increase in fidelity. In my experience, those improvements which prove most fundamental and genuine tend to be consistent throughout the audible spectrum, conferring greater cohesiveness, refinement, and presence to the entire presentation.

Tonal changes, particularly positive ones, are usually expressed with references such as "tight, focused bass," "good midrange detail," "extended and silky highs," etc.---all laudable individual attributes. But the kind of subtle yet significant improvement I'm speaking of breathes new life across the entire range of sonic attributes, enhancing every aspect of the musical experience.

This is what happened to me with the Vibraplane. A certain synergy permeated the individual elements of the usual sonic checklist---and, in a way, superseded them. As a result, I found myself absorbed in one record after another, with barely a thought about sound quality. Clearly, sophisticated pneumatic isolation is a technique that deals with external vibration at a more fundamental level than the usual practices of rigid coupling and elastomer damping, and yet each of these methods plays a critical role in any comprehensive, logical, effective vibe-reduction plan."

[fdegrove]

Hi,

I am making a case for a gainclone, and the RF noise is kinda bad where I live..

Neither copper nor alu will effectively shield against RFI.
Copper is very effective to combat EMI.

RFI can be tackled at the input of the amp by means of filtering (usually this limits the bandwith too),a small .01 mF ceramic cap across the input is quite effective or the use of a steel enclure is very effective as well.

Cheers,

[JordanG]

Originally posted by fdegrove
Copper is very effective to combat EMI. RFI can be tackled ... the use of a steel enclosure

Ok.. So maybe steel case lined with copper.. Here's my concern though. My heatsink is aluminum, and is going to make up one of the sides of my case. I was thinking I could put the copper between the heatsink and the IC, as copper is going to do a good job of conducting the heat to the heatsink. But steel is just no good at that. So then my "steel box" will be missing a wall.. Or I suppose I could cut out just the area where the IC will attach to the heatsink. Will that undo the RFI shielding?

--Jordan

[fdegrove]

Hi,

Will that undo the RFI shielding?

No,you should still be fine.

Cheers,

[Peter Daniel]

One other way would be placing heatsinks inside the chassiss and use a sort of perforated steel panels around. But is the RFI so bad in your area, that you have to go through all that trouble?

[Peter Daniel]

Here's how I build my RFI shielded Clone. I found an old amp, removed everything out except for transformer which is perfect for that purpose, cut the chassiss in half and with few mods and additions I have a very nice chassiss. I bought the amp for $50.

[Peter Daniel]

And here how it looks with a top on. I only had to add side panels, front and rear. Everything else is reused.

[planet10]

Originally posted by Peter Daniel
I found an old amp, removed everything out except for transformer which is perfect for that purpose

What amp? so we can keep an eye out for them.

dave

[Peter Daniel]

An old Dyna Reflex, pretty nicely built actually.

[jh6you]

Originally posted by Peter Daniel
I found an old amp, removed everything out except for transformer which is perfect for that purpose, cut the chassiss in half and with few mods and additions I have a very nice chassiss.

Mmm... what a smart guy!