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Ergo Number Nine - Adventures in Micromonitor Design

James

God has a timeline ... he obviously did not want me to build the 3s ... although all the mdf sides have been formed and routered. He moves in mysterious ways.

Destiny has directed me to the 9s.

Have you any detailed plans?

quincy
 
Quincy,

quincy said:
Have you any detailed plans?
Click to expand...
No, not just yet. I can, however, give you the dimensions of the cabinet as a starter. It's 305mm tall, 190mm wide and 255mm deep. I'll ask Stevea nicely if he would use his CAD software to draw the plans.

James
 
James,
Quick question, do you (or do you need to) take into account the cabinet internal volume displaced by the drivers? In such a small box the drivers seem to swallow up the volume quite significantly.

There seems to be a lot of ABW around, I wonder if I can lay my hands on some Rosewood.
Ashley
 
Ashley, the internal volume displaced by the drivers is around half a litre by my estimation, and the XO will take up another half. Not a lot to lose any sleep over with a 9L sealed box design. In any case, a light to moderate degree of stuffing will make up for the lost volume. The 9L should result in a maximally flat alignment (Qtc = 0.7) and an unstuffed 8L is only slightly higher. You'd have to go down to around 5L to get the emphasised midbass that the LS3/5a is known for.

Rosewood is lovely. Is it an endangered specie or one that is only marginally so? I think Bubinga falls in the later category but I can't be sure.

James
 
James, When you said you could design the speaker for free space or for up against a wall. Is this done by the size of the box or the crossover? . . . . . Mine would have to go no more than 150mm off the back wall.
 
fatmarley said:
James, When you said you could design the speaker for free space or for up against a wall. Is this done by the size of the box or the crossover? . . . . . Mine would have to go no more than 150mm off the back wall.
Click to expand...
Mat, it's all in the crossover. The box size remains constant. I normally design for free space (but in room) placement, which normally requires the mid and treble to be attenuated by around 3-5dB relative to the bass compared to a boundary design. We can play around with the baffle-step adjustment when the time comes to simulate the XO.

James
 
James

Did you use plywood for the fillets because you had run out of walnut?

I checked my supply a few minutes ago and it is depleted so I am sourcing some stock this afternoon.

I should have the raw walnut in my hand in an hour or so.

quincy
 
James

I was checking thru the stocks of ABW at my suppliers yard when I noticed that amongst the rough timber there was a pallet of steamed and planed
lengths ( one inch thick ).

I lifted 11 of them ( 2.61 cubic metres )

TOTAL : £95.29 including VAT.

The guy behind the sales counter told me that the other hardwoods were selling around £20 per cubic meter.

I am off to my local DIY store to cast my eye over the Makita range ( calm yourself Mr Tibbs !! )

quincy

quincy
 
James

You appear to have used #0 biscuits in a #20 slot.

I assume that you did this to give you some leeway when clamping.

quincy
 
Quincy,

quincy said:
Did you use plywood for the fillets because you had run out of walnut?
Click to expand...
That is partially correct. However, as they are glued flush to the rebated edge of the hardwood body (and therefore the baffle will be bolted tightly against the main chassis, so to speak) I don't think it would make a great deal of difference whether you used 18mm square marine ply or walnut.

quincy said:
The guy behind the sales counter told me that the other hardwoods were selling around £20 per cubic meter.
Click to expand...
:eek: :eek: :eek: Twenty quid per cubic metre?!!!! :eek: :eek: :eek:

You're having me on, aren't you? I paid the equivalent of NZD4K per cubic metre (roughsawn) for Sapele, and ABW goes for around NZD6K/m3. Someone here is making a killing! Please tell me it ain't so. If hardwoods are so cheap in the UK, I might have to consider shifting production of the Ergos to chez Dubois. ;)

quincy said:
You appear to have used #0 biscuits in a #20 slot. I assume that you did this to give you some leeway when clamping.
Click to expand...
That's very observant of you, Quincy. I did use #20 biscuits but posed the photos with #0s. #20s in a #20 slot still affords around 5mm of lateral movement either way.

James
 
James said:
If hardwoods are so cheap in the UK, I might have to consider shifting production of the Ergos to chez Dubois. ;)




James
Click to expand...

Got a rough quote today for 3mtrs of 19 x 265 BAW - £270!!

I've found a joiner who has some sapele and he wants £50 for it. He has his own workshop and will plane it up for me ( I may even get him to do the rebates )

He's away for a few days but when he's back i will see if he can get some cheap BAW.
 
james

Mr Tibbs rang to say that you had fired up a rash of emoticons.

I bought 2.61 cubic feet of ABW ... but if you do the conversions it looks like you Kiwis are being ripped off.

I am having problems posting pics to the thread but Mr T will upload one for me later.

The Makita mitre saw ... what is the maximum width of board that can be offerred up to it?

quincy
 
fatmarley said:
Got a rough quote today for 3mtrs of 19 x 265 BAW - £270!!
Click to expand...
Even at NZD prices, that's a rip off. Are you sure he wasn't quoting you for 3 cubic metres instead of lineal metres?

I've found a joiner who has some sapele and he wants £50 for it. He has his own workshop and will plane it up for me ( I may even get him to do the rebates )

He's away for a few days but when he's back i will see if he can get some cheap BAW.
Click to expand...
That's better. You'll need to make sure the rebates are cut 7x25mm on one edge (to accommodate the 25mm baffle) and 7x19 on the other, assuming 19mm finished thickness, for the 12mm frontal edges. The finished width of the boards should be 255mm, give or take 1mm.

James
 
quincy said:
Mr Tibbs rang to say that you had fired up a rash of emoticons.
Click to expand...
He did, huh? At the prices I thought you got, I'd arrange for you to send me a container load of ABW.

I bought 2.61 cubic feet of ABW ... but if you do the conversions it looks like you Kiwis are being ripped off.
Click to expand...
Agreed. That's still a very good price, about one-third of what we have to pay here.

The Makita mitre saw ... what is the maximum width of board that can be offerred up to it?
Click to expand...
The LS1013 with the 255mm blade (if that is the one you're considering) will cut up to about 280mm in a single pass. But the thing is so accurate that you can turn a board twice the width around (as long as the edges are perfectly parallel) and make a perfect straight cut. It'll be plenty to cut the 255mm boards required for the E-IXs.

The Makita is a superb tool.

James
 
James said:
Rosewood is lovely. Is it an endangered specie or one that is only marginally so? I think Bubinga falls in the later category but I can't be sure.

James
Click to expand...
Ahh yes, real Rosewood would be very nice but is unfortunately a protected species, as pointed out by PigletsDad. I was referring to either Bubinga or Indonisian Sonokelling which are both sold as a Rosewood substitute, I shall have take have a trip up to Yorkshire and visit the wood yard.
Ashley
 
I am having problems posting pics to the thread but Mr T will upload one for me later.
Click to expand...

At your service;

abw.jpg


Mr Tibbs

PS That Makita is going for a good price here , plus you get to choose a free site radio or cordless drill :)
 
And to think I almost sold the Makita after I had finished building the deck ...

I'm such a hoarder. :D

James
 
James said:
Even at NZD prices, that's a rip off. Are you sure he wasn't quoting you for 3 cubic metres instead of lineal metres?


That's better. You'll need to make sure the rebates are cut 7x25mm on one edge (to accommodate the 25mm baffle) and 7x19 on the other, assuming 19mm finished thickness, for the 12mm frontal edges. The finished width of the boards should be 255mm, give or take 1mm.

James
Click to expand...

He said it was going to be very expensive before he did the quote. I guess what that really means, is :- I'm going to try, to rip you off!
 
James

That Makita saw is big bucks ... you could fill a workshop with ABW that would last you for years for the same cost ( at Northern Ireland prices :D )

My question : surely a cut from a 45 degree router bit would be just as accurate?

quincy
 
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