A new rack design - light and rigid school (relatively long) - David Aiken

Tweakers' Asylum

Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ.

A new rack design - light and rigid school (relatively long)

203.54.129.245

On Friday night, I finished assembly of my new rack based on my own design. No photos as yet - perhaps in a week or so when I get a friend to take them, and I'll then try to post them somewhere with a link.
That means we're down to verbal descriptions and I'll try to do the best I can.
The rack is made of 25 mm (1") square section aluminium extrusions welded together. I had the cutting and welding done by an aluminium fabricator. For each of the 3 shelves, the front and back aluminium sections rest on top of the left and right hand side sections, with each aluminium section extending 25 mm beyond the bars it touches - imagine a rectangle with each side extended slightly beyond the corner. The extension beyond the corner is 25 mm and the upright in each corner is welded into that angle. As a result, each aluminium piece is welded separately at each corner to 2 other pieces at right angle to it. This makes the frame quite rigid and stable and also means that the ends of each aluminium piece are exposed so that you can access their interiors for filling/damping.
On the top layer, two further aluminium sections are welded from front to back between the front and back bars. The purpose for these will soon become clear.
The bottom of the uprights has an aluminium piece welded over them (the only ends closed off permanently) and tapped to take the threads from a threaded cone as a levelling foot. I'm using Tiptoes speaker cones.
The interior of the aluminium sections is stuffed tightly with compressed polyester batting for damping and the ends are then closed with plastic end caps tapped into them. The polyester is quite effective for damping and is virtually weightless. I was tapping the plastic end caps in using a mallet as I finished stuffing each section. There was noticeable ringing of the structure when I tapped in the first end caps after stuffing only 2 of the sections. By the time I finished stuffing of all 18 sections, there was minimal noticeable ringing when tapping the last end caps in with a mallett, even though I had to tap quite firmly. Rapping the finished sections with fingernails, they're quite dead sounding with an immediate decay and no hangover.
Now to shelves - there are NO shelves!!! The horizontal struts are placed to directly accept the points of the cones beneath my isolation platforms, for the amp and the two extra front to back bars on the top are designed to take the cones for the platform for the CDP. Everything ultimately rests directly on the aluminium sections. When you look at the completed rack with gear mounted, you look straight through the rack - there's nothing to block your view anywhere.
Overall, the finished rack weighs only a few pounds - I've carried heavier shopping bags from the supermarket - yet everything is quite stable. It just takes a little bit of getting used to seeing everything sitting on 25 mm wide bars. When I said light, I meant it. The only way to reduce mass that I can see is to make the rack smaller.
Now to the sound - it's the cleanest sound I've had from my system and extremely neutral. I can't notice any colouration anywhere. One of the first things I noticed was the extent to which the bass end cleaned up - the best description of the effect that I can give is to say that it reminded me of the improvement I got on installing bass traps. I lost "overhang" or "time smear" I wasn't aware of. Actual bass notes are clear and as well defined as the recording allows with extremely good extension and detail in this area is much clearer. As an example, Chuck Berghofer's acoustic bass solos on Joni Mitchell's "From Both Sides Now" stand out clearly against the backdrop of the orchestra, with detail of string bass tone and orchestra parts not interfering with each other. I can hear much more easily what's going on in complex combinations in the bottom end where before the different parts and instruments tended to "blur" and obscure each other to a much greater degree.
While I've concentrated on bass because many people think that good bass requires a massive support system, this clarity extends to the midrange and high frequency ranges as well. The soundstage is also wider, deeper, and less congested which I also think contributes to the clarity. Tonal colour is richer and more natural. Voices in particular are very lifelike in tone and, like individual instruments, stand in clearly defined locations with "air" around them. Despite the fact that there is no wood in the rack, the sound is definitely not "metallic" or hard in any sense, and I've never had voices sound so "human" before.
Transient response and "snap" on percussion is superb.
I think part of the clarity and openness comes from the fact that there are no shelves to provide large reflective surfaces. The rack has to sit between the speakers - I have no other choice for placement - and there is noticeable improvement in imaging. I have no doubt that getting rid of the large reflective surfaces of the shelves is a significant contributor to the improved openness and imaging.
Dynamics, both macro and micro, seem improved and this is consistent with my previous experiences in reducing mass in my system by removing granite and replacing lead and sand with polyester batting for damping purposes. Music seems "liver" as a result, especially good live recordings.
OK, so there have to be some problems. There are, and they have nothing to do with the sound.
This is a "fidgety" rack in that you have to make it precisely to measure for your gear. In addition, things don't have to move far to fall off - around half an inch to be exact. That means this rack is no good if you have small children or if you live in California or anywhere else where you're likely to experience earth tremors. It's no good if you change gear frequently because the new gear simply may not fit. In practice in my house - two adult occupants and one large dog and a slow gear turnover pattern - I'm experiencing no problems with stability, and I ran with a mockup of this arrangement for around a month where I took the shelves off my Lovan rack and tied aluminium sections to the frame with cable ties to test whether there would be a sonic advantage to going this route. That mockup was a noticeable improvement over the Lovan rack with shelves but the finished product is still noticeably better again. I did not expect to get the improvement I got over the mockup from the finished design.
The other drawback is cost. It's not cheap and most people would need to get someone to build it for them because of the need to weld aluminium. That tends to put it more in the category of design it yourself rather than build it yourself. Overall, the cost came in at just under $500 Australian or $250 US for a three "shelf" rack, and I can't think of anything I've seen here at a comparable price that could touch it for sonic benefits.
It's not limited to use with cones to support gear - you could easily modify it to take Aurios, DIYumas, or your isolation footer of choice - but the same restrictions will apply. You need to know exactly where your footers go in relation to your component and to measure those placements extremely accurately in order to determine the dimensions of the frame.
It's the ultimate minimalist rack - there's absolutely nothing you can remove from the design, and it has proven remarkably effective in my system. I'm happy to handle private emails about it and to forward pictures to clarify construction details when I get them.
I also expect to field a few comments to the effect that I'm crazy and no-one in their right mind would ever build a rack like this, but my response to that will simply be that this is an asylum and I'm not claiming to be in my right mind :-)
I hope at least some people enjoy reading this and that it prompts a bit more discussion on what the essential requirements for a good support system for our gear is, but I feel more and more strongly that the light and rigid approach yields benefits that can never be obtained by mass loading and produces those benefits with no down sides when done well.
I'd like to thank inmate Bald Iggle for email discussion of some of the design features, and Ken Lyon and Simon Linton for doing much to convert me to the light and rigid school last year. Having said that, the design of this rack was all mine and those inmates should not feel discouraged to query my approach or raise concerns. I know there's still a fair bit I can learn in this area, even if I'm very happy with the outcome here.
David Aiken

This post is made possible by the generous support of people like you and our sponsors:

VH Audio

Topic - A new rack design - light and rigid school (relatively long) - David Aiken 01:36:00 09/04/01 (11)

A problem. . . - Hantra 11:44:17 09/06/01 (2)

Re: A problem. . . - David Aiken 12:52:46 09/06/01 (1)

Kewl!!! <nt> - Hantra 13:05:30 09/06/01 (0)

Use aluminum fence uprights???? - Bruce Righter 05:25:22 09/04/01 (4)

Re: Use aluminum fence uprights???? - David Aiken 12:31:44 09/04/01 (3)

Re: Use aluminum fence uprights???? - Hantra 11:48:10 09/06/01 (1)

Yes, it's on spikes (threaded Tiptoes speaker cones) for levelling (NT) - David Aiken 12:47:12 09/06/01 (0)

Re: Use aluminum fence uprights???? - Bruce Righter 15:27:39 09/04/01 (0)

Re: A new rack design - light and rigid school (relatively long) - JDK 03:33:04 09/04/01 (0)

... one further "thank you"... - David Aiken 02:55:48 09/04/01 (1)

12 step sponsor? - dave c 13:48:51 09/04/01 (0)

You can not post to an archived thread.