Archive for category Hifi Rack – The Minimalist

The Rack – Results

I need to go and buy a cable organiser. Otherwise, it looks pretty cool.

The Minimalist Rack In Action

The Minimalist Rack In Action

OK, so a number of people have been following me on this journey. Here’s the info you wanted:

- Total cost of materials: about $500 AUD. The acrylic was around $300, but was cut to size and all I had to do was polish the edges. The steel was around $50. The rest was paint, sand paper, etc. I did get the feet for free and they may cost a bit normally, but I suppose you could use something like spikes on a metal floorprotector or something. My only concern with that is if you accidentally put that into your floor or your foot, the results will not be pretty. The entire rack weighs probably around 60kg or so. I completely botched up the calculations before. The shelves weren’t 2kg each, they’re about 8.5kg each. So just the shelves weigh in at 34kgs.

- Welding can be difficult at the start but if you practice a bit, you’ll get the hang of it. I wouldn’t recommend building a rack like this if you’ve never welded before, due to the 90 degree joints which are much more difficult to weld than a flat butt joint. So if you’re doing this for the first time I’d recommend practising HEAPS before you start zapping your final work. One good thing about welding is that you can grind down any mistakes.

- I hate filling. I HATE filling. Did I mention that I hate it? Maybe it’s because of the hot weather and my inexperience, but I had to redo some of the filling about 8 times before I got it right. It’ll certainly be easier next time, but can I just say…I hate filling. The sanding part kills me.

- When I first approached my design I thought alot about rigidity and lowering resonance by having high structural strength. But if I had to do it again I’d be more adventurous with the design. The steel I’ve used is extremely strong. Even when really stretched they hardly flex at all, and after some research (& my own experimentation) I found them to be less resonant than aluminium. Next time I’m thinking of removing the T joint at the top, and be even more minimalist…

- The whole thing took me around a week to build, working about 8 hours a day. Not exactly worth the time strictly, but it was a lot of fun in the end and even though my fingers are still a bit red fron sanding, I’d do it again.

- Next time I build a rack (this time next year at earliest) I’m going to try fill it in with lead shot as well as sand. This would make it even more rigid and less resonant.

Anyway, so here’s what really matters:

I can’t say if it makes a huge impact on the sound, but it certainly makes some impact. It’s rather hard to “test” given that I can’t easily shift my system on and off my rack. But I’ve noticed that it improves the sound of my CD/SACDs much more than LP. I used to listen to CDs and find it slightly more detailed but quite colder than LP. But now it’s really getting quite close to LP quality in terms of “thickness”. It’s obviously still not as warm or a “charming” kind of sound, but with this rack I’d say that for the first time in my hifi life I’ve considered selling my turntable.

But fear not! For I won’t. I have too many records and the phonostage is a crappy old one I built years ago. I’m quite certain if I replaced it then LP would be back in front, but it’s an indication that the rack may be doing something right.

Detail, realism, “thickness”, height and to some extent soundstage were the key improvements on CD. The LP improved slightly but I don’t feel that it was a huge gain in any department. They’re my initial thoughts on the sound. I’ll keep listening and report on results…

If you guys have any more questions, please feel free to fire it my way. Use the contact page up top that Ed has kindly set up.

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The Rack – FINISHING

Ok so everything’s done and I just gotta put it all together tonight.

Sand fill, bolts installed, shelves cleaned and installed…

Sand Fill

Sand Fill

Again, if you were to do this, remember to use kiln dried sand.

Bolt Stopper

Bolt to stop the sand from coming out

The Frame

The Frame Complete

I’m quite happy with the way it came out. It’s quite an industrial sort of minimalist look.

Complete

Complete!

Cleaned up the acrylic sheet. I used silicon self adhesive rubber feet to mount the acrylic onto the frame.

Finished

Finished!

So Shiny

It's So Shiny!

Unfortunately it’s nearly 12am and I won’t be able to listen today. Results will be published in the coming days.

I’m tired…

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The Rack – Shelves

I ordered some acrylic shelves a while back and now I have to polish their sides. I’m using a polishing wheel attachment on a drill, and some metal polish. I also bought some of this vuplex stuff which does the final clean and buff.

Results are in:

Shiny

Shiny

Smooth

Smooth

Smooth and shiny. Mmmmmmmmmmmm…..

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The Rack – Painting Day

One good thing about hot, sunny weather is how fast you can paint. Today’s the sort of day I can prime, undercoat, and topcoat in about 20 minutes. Unlike filling, painting I like.

Got up early to paint, and it’s already done. I decided to go for a matt silver finish. 2 coats of primer and 4 undercoats, plus a topcoat.

Undercoat 1

Undercoat 1

Undercoat 2

Undercoat 2

Undercoat 4

Undercoat 4

Painting DONE

Painting DONE!

Lookin' good

Lookin' good

Surface

Surface...not too bad, I think...

Having a break now, and while the frame sets I’m going to start polishing off the acrylic. I’ve purchased a polishing wheel attachment for my drill, with some metal polish. More to come today…

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The Rack – Fill Day 2

Guess what I did today?

Yes…fill.

Filling Almost Done

Filling Almost Done

Filling Done

Filling Done!

Done...finally

Done...finally

I’m never filling again. Certainly not in the heat.

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The Rack – Fill Day

Wow. I hate filling.

Maybe it’s because my lack of experience. But god it was hard work. It’s been rather hot here and the auto filler hardens in about 30 seconds – before I could even stop mixing. By the time I’ve put the stuff onto the rack, it’s the consistency of chewing gum. I had to redo alot of the filling.

Filling

Filling

More Filling

More Filling

Even more filling

Even More Filling

More tomorrow. I’m done for today.

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The Rack – Structure Complete

I’m rather tired, but at the same time pretty excited. Have a look at today’s achievements.

Legs, stoppers and rests are all on.

Legs

Legs

Rests

Rests For The Shelves

Completed Frame

Completed Frame

Tomorrow is going to be fill day. Fill fill fill…

Not the most exciting part. I hate sanding. But the results should be worth it.

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The Rack – Frame Is Up!

Got up at 6am this morning to start building. I must admit, I was surprised at how quickly and easily I was able to put the basic thing together. I mounted everything on a flat surface, clamped it down, and within an hour I had a free standing structure.

Check it out!

Rack - The Minimalist

Frame

Angle grind down the welds, and voila.

I also welded some nuts onto some squares which fit the ends of the columns. This is going to be used as stoppers for the sand fill.

I made a little bottom sealed compartment to put the legs in.

Stoppers

Stoppers

Speaking of legs, here’s what they look like:

Legs

Legs

As you can see, the critical part is a ball that rests onto a rubber covered steel plate. They’re also super adjustable.

Picked up my acrylic sheet (AKA perspex) as well. Check it out…

25mm Acrylic Sheet

25mm Acrylic Sheet

They’re super heavy (about 1.5-2kg each), and sonically dead. (ed: matt botched up the calculations, they’re actually 8.5kg)

Tomorrow, I’m planning to mount the legs, mount the shelf rests and finish grinding everything back.

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The Rack – Materials Purchased

Went out and bought materials. Being in Australia, there’s not alot you can source in terms of cool extruded aluminium or shelf fittings. We only have structural mild steel, nuts, bolts and to be on the exotic side, my dad’s awesome vibration isolation feet.

Anyway. Here’s a list of the stuff:

- 65mm square mild steel, 3mm thick (Inspired by when I built a shed with the same stuff. It’s cheap, easy to weld and very, very strong).

- A bag of kiln dried sand. If you’re ever planning to fill a rack, speaker, plinth with anything, you MUST use kiln dried sand. Normal sand has moisture still in the grains and, over time, will cause rust, mold and general unpleasantness. Stay away from normal sand.

- 25mm acrylic sheet shelves. I decided to use acrylic instead of MDF. It not only looks better, but has more mass. It’s also acoustically dead, and the same material as that of my turntable platter. Cool…

- Nuts, bolts, to finish the sand fill stoppers and to attach on the legs.

- Heavy duty, vibration isolating, full adjustable feet. These things can swivel, adjust for angle and height. I’m not sure what their cost is but I suspect they’re pretty expensive. They’re sourced from my dad who works in precision engineering. They use these feet to mount huge machinery which need vibration isolation to achieve extremely low tolerances. Lacking this I suppose you could use good old spikes or ball bearings on metal floor protectors (which ideally should be rubber lined on the bottom).

- Auto body filler.

- Steel weld wire.

- I still need to get paint, but I haven’t decided on the colour yet.

More to come soon. Here’s a picture of what the steel looks like:

65mm Square Mild Steel

65mm Square Mild Steel

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The Rack – Design Complete

I’ve done a good amount of research over the last week. Obviously the key design requirement for a rack is to have super low vibration at any point that is contacted by the equipment. I.e. the shelves. There’s a lot of junk on the internet about what makes a good rack, but from a more scientific perspective I think it comes down to the following factors:

- High Mass

- Some form of damping

- Unit stability

- A low structural resonant frequency

- Structural strength, yet at the same time achieving the above

- Level adjustable

To control vibration of the unit as a whole, the first 3 points apply. To control internal resonance, which is by far the most important aspect of reducing vibration, all first 5 points apply. Level adjustability is simply to help with CDs and LPs spin on a horizontal plane.

So I think I’ve come up with something like this:

- Minimalist design (since my skills in metalwork are limited)

- 65mm mild steel columns, sand filled do deaden vibrations. I believe steel is more resonant than aluminium, but thick extruded aluminium is hard to find and difficult to weld. It’s also more difficult to finish, although theoretically I could leave it unpainted. Unfortunately my confidence in welding limits my desire to use it.

- Thick MDF shelves (acoustically dead)

- Three feet design

- Vibration isolating adjustable feet (I’m able to get some from my dad, who works in precision manufacturing. They have feet for heavy machinery which are not only completely adjustable, vibration isolating and limiting, they can handle a huge amount of weight).

I’ve been thinking about how I was going to couple the shelves to the rack. The internet tells me to use spikes. They’re the most popular form of contact for any “high end” rack shelf. But I’m not really convinced that it’s a good idea. Ideally with a vibration reduction system you need not just high mass but good damping. If the shelf is much less resonant than the frame (which MDF definitely is), it’s much better to damp the coupling layer rather than fix it. You’d still want the frame to be as unresonant as possible, but it’s never going to be able to achieve the natural deadening properties of wood.

Anyway, the drawings are done. But I’m not going to post them here as my artwork skills are horrible. Going out to buy some materials now. Back later…

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