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.
128x128chilehed

Hi Chilehed

I design a lot of audio platforms and racks out of different types of pine and it can be one of the best sounding materials to use, but if done incorrectly can sound horrible.

It's too late to go back and reclaim the pine if you have already finished the surface, but there are some things you can back step that will help.

(1) get rid of the dampening

By now you know there is no such thing as isolating in the audio range. Your products are going to sound like your rack. Once you get rid of the dampening material, your going to hear some of the equipment range come back. You will also hear your room sound better.

(2) how is the wood finished

What type of finish have you used and how many coats, and how was the surface sanded? Pine takes a very long time to cure (especially that thick). If you live in a humid area you could set a dehumidifier in the room and set it at 30-35%.

If you would like you can get ahold of me from my website and I could walk you through some things. http://www.michaelgreenaudio.net/

Your probably a lot closer to good sound than you think, it's just that pine is such a wide range wood type it's easy to get lost in the voicing of it.

Michael Green

Hi Michael,
I can remove the damping material easily enough and will give that a try.
I got the pine slabs from a local mill and have seen no movement (expansion / contraction). The fellow I bought them from told me they were dry and it seems he was right. I live in the northeast so we get some pretty wild swings in humidity. The original boards were 2" thick and I had them surface planed and then I used a palm sander with 60, 120 and 220 grit sandpaper. I finished the boards with Minwax stain then Minwax Helmsman polyurethane (3 coats). 
Thanks for the feedback and advice.

Hi Chilehed

Yep after the dampening is gone you should give another report. And from there I'd be happy to help.

220 is going to close the pores so the poly isn't going to soak in as much but with pine you still might be ok (will just take longer to cure). A dehumidifier will help.

I do my pine in the desert so I start off super dry, and then cure it a long time before I start my sanding and coating. After I cure the wood it is about 1/3 the weight of when it was at the lumberyard.

But, that's not where you are at, so your going to need to be patient as the 3 coats is going to take a long time cure for you.

After the dampening is gone (be sure to sand and refinish where the dampening was) your still going to hear a cloudy sound. In time that will clean up. Your also going to want to look at what type of feet your going to want to use under your components.

What components are you using and I can make some recommendations for you when tuning in the transfer.

I had homes in Ohio and NY NY, so I'm pretty up on your curing area.


have a good weekend


mg

Hi Michael- Nice to see you posting here on the forums!

Would brass cones help if used below electronic components to "decouple" ?


David Lynch

@chilehed
I did improve things by putting three granite sample blocks under the turntable and tube preamp. You don’t say what gear you are using so not sure how it will effect things. You can check out some of my pics in Systems.