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DIY Audio Rack [*fail*]

Seen a few discussions on this topic and wanted to chime in with my experience. A recent amp upgrade necessitated a change from the "Solid Steel" rack I was using. New amp is deeper and taller so I needed a solution to provide deeper shelves and more clearance for ventilation. Didn't see a lot of offerings that were aesthetically appealing enough to motivate me to immediately bust open my wallet, and a few months earlier I built a "live edge" bar height table to accommodate extra seating in my listening room. The table project was fun and turned out very decent and provided the form and function I was looking for. With all this in mind I thought it would make sense to maintain a consistent look and build a rack using the same materials. Form factor of the Solid Steel rack is 3 shelves in 2 columns accommodating 6 components. I was keen on lowering the profile of the new rack as it is situated in front of an 8' casement window with a low sill so I built it using two shelves which are 65" wide to accommodate the width of 3 standard components. 
Materials used for the table and new rack are 2" square steel tubing that I had fabricated by a local welding shop. The shelves are made from 2" thick live edge pine that is milled/finished to ~1 3/4" thickness. I had concerns using pine, but after working with it I prior, it felt heavy and solid and I thought it would have the density to not negatively effect the sound in the room. The rack is located on the front wall between the speakers so I thought that by lowering the profile, there was an outside chance I might even get better sound. Lastly, when I assembled the rack, I isolated the shelves from the frame with 1" wide by 1/4" thick neoprene tape. I also used rubber washers between the screws and the frame so  the shelves and the steel frame are isolated from one another.
Once I got the rack assembled I was more than pleased with the look. I was seriously chomping at the bit to get it situated in the room with components installed but didn't right away because I really enjoyed just looking at the finished product. I recruited my son to help me move it and was really encouraged as the thing is a beast and weighs a lot. 
I installed components into the new rack, powered everything on and gave it about 30 minutes before I queued up the first song. I think I was still interested in how great it all looked when the music started but it didn't take more than several seconds to realize something had changed and I don't mean just a little. It was like someone put a blanket over each of my speakers. It seems that aside from building a fine looking rack, somehow I also succeeded in building a broadband attenuator that does an awesome job of damping most of the audio spectrum in my room and is particularly harsh on low and mid frequencies. Of course as this happened I shut everything down and rechecked and re-seated all my connections which changed nothing.
I've been super busy since completing this project but in the coming weeks will start to systematically deconstruct the setup to better understand the culprit(s). I am reasonably sure the pine shelving is at least part of it but am interested to see if the isolation technique I used is also damping the sound somehow? I phoned one of the rack companies that advertises a lot here on A'gon and a gentleman (forgot his name) was kind enough to answer some questions for me and mentioned that the coupling technique I used could be a major offender and that there are different schools of thought for when to isolate and when to couple directly. While I am going through this exercise I'll also experiment with moving my components (or most of them) from the front wall to an alternative place in the room. 
In the end I just wanted to share the experience with others that might be considering a similar effort and to say that there is much more to this than meets the eye. I didn't realize how much material, construction technique and perhaps even form factor (size and shape) can all make a dramatic difference. Since all of this transpired I've read a bunch of reviews on racks and many of them comment on the sound of the rack....I probably would have called BS on this before doing this project but now I am a true believer.
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geoffkait's avatar
geoffkait
23,365 posts
 
By the way, I’m not entirely dismissing the original Michael Green brass cones - the really nice tall brass cones with a long ballistic tip, which are *very* good sounding. Alas, in the competitive world of high end audio there is always the risk of a faster gunslinger coming into town. But things got considerably more complicated in the past twenty-five years, you know, what with the advent of vibration isolation methodologies and new high-performance cone materials.

I don’t think there has ever been a comprehensive and scientific evaluation of competing audio cones but I think it would be interesting to see, including but not limited to Shun Mook, Mapleshade, Black Diamond Racing, Michael Green, Marigo, the original Tip Toes, Golden Sound, Starsound, Herbies, whatever. The Cable Company lists 4 pages of audio cones, a total of 40 different “cones.”

I do not have a dog in the big cone fight.

Geoff Kait
Machina Dynamica
Advanced Audio Concepts
geoffkait's avatar
geoffkait
23,365 posts
 
theaudiopoint
Since there are hundreds of steels manufactured each with a different chemistry and damping factor, what type of steel does one choose for shelving that manages the pitch variables of hard ceramics in order to outperform a specific brass alloy?

Hardness of materials has little to do with sonic outcomes especially when you take into consideration the rack design which is totally responsible for the cone or footer performance.

>>>Well, it actually might be best to add some caveats to those statements. Racks are not necessarily the best solution for *vibration management* as you call it. No matter what is done to a given rack, even a very stiff steel rack, better results in terms of *sound quality* can usually be obtained by *eliminating* the rack entirely and moving the components to the floor and using vibration isolation devices. Racks by and large, even very RIGID ones, tend to transmit or even amplify seismic low frequency vibration. I would say the whole idea of a very rigid and well damped rack is rather archaic.
uberwaltz's avatar
uberwaltz
13,381 posts
 
Maybe very true GK
But the reality unfortunately for the vast majority is that some type of rack is a necessary evil due to space constraints with amount of equipment owned.
I know I do not have room to spread all my gear out on the floor each on their own separate isolation platform or footers etc.

Perfect world scenarios do not exist for the majority.
bdp24's avatar
bdp24
9,868 posts
 

If sufficient isolation is achieved for every component, the importance of the rack itself is minimized. Maybe not completely eliminated, but close enough for Rock ’n’ Roll---a classic musician’s joke. Audiophiles tend to drive themselves crazy, trying to achieve that last few percentage points of sonic improvement. And all in an effort to reproduce what is highly compromised sound to begin with. Does that sound anti-audiophile? High performance systems are often far better than the source material played on them. A system is only as good as it’s weakest link, and once a system has achieved a "certain" sound quality level, that is generally speaking the recording and/or storage medium. What level has to be reached for a system to be "good enough" is of course a very personal one.

MG’s basic premise raises the interesting question of how much of any given component's sound quality potential has been realized in the basic design and build of the piece, how much that potential can be more fully realized, and by what means. If can be argued that the less a component’s sound can be improved with tweaks, the better it has been designed and built. Is any tweak going to make up for a, say, power amp’s poor power supply? Would the money spent on expensive tweaks be better spent instead on a better amp? I’m just askin’.

geoffkait's avatar
geoffkait
23,365 posts
 
I know, Uber, but surely you must realize I’m not into the whole vast majority opinion or necessary evils or convenience thing. And I have, I think, made that abundantly clear. Of course everyone is free to choose. Whatever.
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