Electronic enclosure

[Luke123]

hello

I need to have suggestions for standard rack mount and table top enclosures manufacturers for hifi and Pro audio projects.
I used to order Sescom chassis. Not bad but something different would be appreciated.

Thanks

Luke

[acoustixman]

Luke123:

I recently built an amp into a Lansing B-style Graybox. They are beautiful extruded aluminum components. The structure is the most intuitive I have seen (side panels dominant (and thick!), front and back between, top and bottom last). The front, back, and side panels have internal "lips" top and bottom which can be used as I did to mount a very strong internal skeleton. It's like a brick outhouse, and without all the corner pieces and small hardware you sometimes see (8 screws hold it, before rack-mount ears are placed.

They have shielding, venting, internal PCB guide, and color options, and the B-style is certainly not their only offering. It is however the one I will use for my next project.

The website:
http://www.lansing-enclosures.com/siteatlas/

Happy constructing!

[Luke123]

Acoustixman

Wowww!
Thanks for the cue!
In fact it is a beautiful line and I think much better thant the Sescom line I used to buy. Looks so versatile. Intelligent features.

But in term of built quality and overall finish, how does it compare to Sescom? Much better?

Luke123

[acoustixman]

Originally posted by Luke123
Intelligent features.

But in term of built quality and overall finish, how does it compare to Sescom? Much better?

Luke, to be perfectly honest with you I have never used any kits besides the black-anodized Graybox-B. The anodizing is as good as I've seen; consistent even finish... The surface of the extruded parts has bits of "brushed-look" extrusion artifacts (makes more noise with fingernail dragging across than lengthwise if you know what I mean). I personally favor that appearance; looks sort of industrial. All blemishes in this project were caused by ME. It's a prototype...

For fit, the chassis can't be beat. The actual dimensions are perfect. My measurement of the parts before setting about milling my internal framework was unnecessary; the specifications were abided to a T by their production. The front and rear panels are identical, and they contain extrusion guides which are tapped for the assembly screws. The side panels mount upon the front/rear, and the screws are countersunk. The alignment is excellent. When I got the box out of the shipping box, I of course put it together. It assumes perfectly flat (4-point) stance on known flat bench top. All I had to do to get it to full strength was install 8 screws, 2 per corner, and tighten.

My favorite part is the L-angle extrusion inside top and bottom perimeter (provides mounting surface for top/bottom yet also internal structural bearing.

The only complaint I have is that the top and bottom panels (sheet / not extrusion) are drilled slightly off so that the countersink screws there can't all center at once. The top and bottom panels have the least dominance (strength is almost completely provided by sides and front/rear, even most of "footprint parallelogram" rigidity) so this is not a big deal for me. The top and bottom mount to an inset area created by the front/rear/side extrusions and are not part of the footprint if that is a good visualization.

Zis help?? I'll try to get you a couple close-ups, but our digital camera is busy at the moment...

[acoustixman]

OK here we go... This should give a good idea of how the panels assemble and the internal structure flexibility you have with these boxes... Hopefully you can also see the surface finish a bit... This is my first photo upload... bear with me... May have to edit.

Like I said the nix in the finish are my own...

[acoustixman]

Guess it worked. Cool. Here's one more angle.

[Luke123]

Acoustixman

Thanks for the photos.
In fact the chassis really looks seriously built.
Nice product for the money.
But about your amp, tell me more about it. It seems to be a long time job!

Luke

[acoustixman]

Luke;

I guess I took this project pretty seriously. It was about 5 months start to finish, partly spent designing and rounding up parts, partly laying out PCBs, partly revising concept and redesigning PCBs...

It's pretty strong; the internals include about 12 feet of 3/4x1/2" 6063 Alum channel (1/8" thick), so at 14.5 kilos it should be mostly OK if it gets dropped from torso height, but I'm not about to do it on purpose.

Key topology influences have been W.M.Leach; low TIM amp,
http://users.ece.gatech.edu/~mleach/lowtim/,
and G.R.Slone's High Power Audio Amplifier Construction Manual (sorry no link but found on http://www.amazon.com/), but I have made some divergences from both. Description OK? So far I know where all copies of the schematic are... I'm still a little afraid to freely distribute it... I promise I'm not trying to be pretentious...

PS: 750VA Plitron toroid (very quiet!), 35A bridge, 2x 37,000uF caps...+/-70V rails... I pull air through with 24VDC fan in rear on aux. reg. power supply, speed is a function of interior temperature.

Amp (x2): Comp-sym (mirrored) quad-cascoded diff in front -> high-beta (non-darlington) mirrored cascoded VA stage with mirrored 2-pole compensation -> BJT class-A EF buffers -> 2x parallelled LMOSFET (TO-3) class-B SF outputs...

Not quite sure of open-loop gain. Moderate degenerative FB provided throughout; (semi-) global FB includes 2x 22pF roll-off direct from VA output + HF control FB from buffers + audio band FB from FETs. +34dB closed-loop. DC coupling throughout - I like to live dangerously (DC-sensing speaker protection included however)!

Class-B biasing turns out pretty easy and clean with Lateral FETs (thermal tracking not necessary) and idles very cool. Most importantly, I am thoroughly pleased with the sound. Transient delivery is crispy! The 2-pole compensation + cascodes on all gain components seem to make it very quick. I'd like to think it's just the right compromise between Hi-Fi and Pro-sound, but of course I am 'biased'...

What about your projects?

[Luke123]

Acoustixman

I was looking for electronic enclosure alternative because I needed something flashier than the usual Sescoms I use for projects.
Mostly chosen for my Lab's custom test gears and pro-audio custom projects.
My next project is an electronic dedicated analog crossover/Preamp for my next 3 way system.

Luke

[acoustixman]

Luke;

Sweet (on the Pre/XO plans)! I have recently been trying to set about designing a similar appliance... My amp is without permanent access to my listening system since it wants to replace a pretty well-featured audio receiver and my wife likes the remote control... my amp can't be turned down without walking over to it. Of course, an active XO means I need 2 more power units...

I'm trying to figure out how rigorously to approach a pre-amp design... I was thinking of using Lin-3/mirror-image topology and low open-loop gain for about 6dB closed... I'm just thinking people use good op-amps for lots of simple tasks, so why not use Lin 3-stage in a pre-amp? ...then again maybe it's too complex to be sensible if very little voltage gain is being done.

What sort of power supply and control section (s.sel / volume / etc.) are you using for your pre-amps? Are you including tone controls and/or balanced XLR inputs? Cartridge capability?

By the way I am definitely going to keep using Lansing boxes (not only because I want everything to look similar); they rock (in the passive sense)!