Cheapish HiFi Bookshelf Speakers Limited Tools NO Aesthetics

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Fred
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Cheapish HiFi Bookshelf Speakers Limited Tools NO Aesthetics

Post by Fred »

Split off from the amp thread!

I ordered some drivers to make speakers to drive with this thing, today! Time to design a set of boxes, and pull my finger out re getting PCBs made!

Thanks to MrOnion for automating my life!

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Re: Simple Cheap Compact IC-based High Performance Amp

Post by MrOnion »

Dude! Hahaha... You learn finnish on the way too. Did this to my friends uncle a while back (well looks like 13 yrs) who publishes hifi magazines. Funny how you find your early "work" is still online and even usable...

.. and reminds you how many fucking years you have been sitting on this damn machine. ;)
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Re: Simple Cheap Compact IC-based High Performance Amp

Post by Fred »

Did this to! LOL! What, like a punishment? ;-)
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Re: Simple Cheap Compact IC-based High Performance Amp

Post by Fred »

How much is that doooogy in the window, toot toot, I do hope that doooogy's for sale, toot toot.

Went to look at wood. MDF. 19mm 300mm 2440mm 8.27l internal volume.

If I were to be horribly and unforgivably stupid and ignorant I'd make it a cube. If I did that, the internal walls, assuming no stuffing, no bracing, no speaker back intrusion, etc, would be:

3√8.27 = 2.02225151688209 decimeters or 20.2225 centimeters or 202.225mm, which would be awfully difficult to achieve with 300mm wide MDF, even after subtracting 38mm + 4mm for thickness and sawcuts.

So given my lack of tools, it'll likely be 300mm ID one way, and 300 - 38 the other, minus 20mm square corner braces, gives us a cross section of:

(30 * 26.2) - (2x2x4) = 770 sq centimeters! DuckDuckGo fucking ROCKS! (mixed multiplication symbols and it still works!)

Converting that to square decimeters is 7.7 more math required:

<went to bed, got up again>

Volume of the bracing is ID of each dimension minus 4cm, times 2cm * 2cm x 2 of:

((30 + 26.2) - 8) * 2 * 2 * 2 = 385.6 ml

(0.3856 + 8.27) = 8.6556

8.6556 / 7.7 = 1.1241038961039

11.241cm / 112.41mm high which isn't big enough for the driver in question, so it'll have to be whatever the driver needs high, and tuned with sand filling.

More as it comes to hand.

Fred.

PS, I'd had a few wines before the <> interlude.
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Re: Simple Cheap Compact IC-based High Performance Amp

Post by Fred »

Speaker cut-out is 145.24mm max, plus 20 on each side for bracing (keep it simple for a simple boy) == ID of 185mm

Caps will need to be 300 + 19*2 long, and 300mm wide == 338mm

So, 8 * 185mm pieces @ 300mm wide + 4 * 338mm pieces @ 300mm wide == total of 2832mm + saw cuts, == two pieces to be diced up.

8 * 185 = 1480 + saw cuts
4 * 338 = 1352 + saw cuts

That's a bit awkward.

Fred.
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Re: Simple Cheap Compact IC-based High Performance Amp

Post by Fred »

Outer dimensions of the box as described above will be 300 x 338 x 225 which isn't quite golden ratio, but is good enough.

225 x 338 will be the front, which sucks, as that'll have the edges of both the top/bottom and sides exposed.

The sides will be smooth with screw holes. And to reduce volume I could inset the back by whatever I want, I guess.

I guess if they don't rape me for cutting fees I could take a few extra small pieces out for bracing internally. But maybe that's not worth it either.

Or maybe the offcuts could turn into a sub box. 4 @ 300 + 2 more @ 338 = a cubic foot and about right for a sealed bass driver.

6 * 338 = 2028

2440 - 2028 = 412 - 32 = 380 == more than 300 (1 out of 4)

2440 - 1480 = 960 - ((8 + 3) * ~5 cut) = fucking near exactly 3 pieces @ 300mm

I guess we'll see what the cutting fees are like! :-p

Fred.
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Re: Cheapish HiFi Bookshelf Speakers Limited Tools NO Aesthe

Post by Fred »

Cuts are 50c each, and a little under 5mm wide, which is what I accounted for, IIRC.

Drivers arrived today! A little treat for Fred. So I went out and bought some stainless steel cap screws to match, and a bunch of various types of stuffing to fill the boxes with.

Need to pick up screws, Chinese jigsaw, glue, sliced MDF, and some square pine for bracing.

Also need to do work on the amp, or I'll never hear them...

Fred.
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Re: Cheapish HiFi Bookshelf Speakers Limited Tools NO Aesthe

Post by Fred »

It'll look something like this, I guess, but without the paint:

http://www.loudspeakerbuilding.com/Maga ... 00952,4353
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Re: Cheapish HiFi Bookshelf Speakers Limited Tools NO Aesthe

Post by Fred »

Final cutting list:

If taken from two sheets @ 2440:
  • 8 * 185 = 1480 + saw cuts
  • 6 * 338 = 1352 + saw cuts (2/6 for a sub)
  • 4 * 300 = 1200 + saw cuts (4/4 for a sub)
Divided in two, so as to guarantee sufficient material:
  • 4 * 185 = 740 + saw cuts
  • 3 * 338 = 676 + saw cuts
  • 2 * 300 = 600 + saw cuts
Per board @ 2440

If just what I really need:
  • 8 * 185 = 1480 + saw cuts
  • 4 * 338 = 1352 + saw cuts
Need to sort out a hole cutting option. So far a 35 euro ching chong router looks like the best (read cheapest) option. Might try to sort that out today.

Fred.
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Re: Cheapish HiFi Bookshelf Speakers Limited Tools NO Aesthe

Post by Fred »

Went on a mission to charge up car battery and get some bits for this:
  • 4.8 meters of 21mm square pine hand-selected for straightness, check.
  • PVA in a bottle with Poly Vinyl Acetate no where to be seen on it, check.
  • 500 No. 2 pozi-drive 4x40 zinc-plated self-tapping wood screws, check.
  • Medium length No. 2 pozi-drive driver bit for cordless drill, check.
  • Dirty, filthy, cheap, nasty, wretched and Chinese wood saw, check.
  • 1L of alcohol unrelated to this project, check. (can't get a litre of meths anywhere here...)
  • MDF sliced to perfection, FAIL. Another day, I guess.
  • A "fresadora" and appropriate router bit for making round holes cleanly, FAIL. Also another day, I guess.
Dinner time! :-p

Fred.
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