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Old 4th August 2005, 02:09 PM   #11
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Bob lines his cabinets, rather than stuffs them, using acouctic ceiling tile -1/2" firbeglass. You canusually get it from people who do ceilings...
Yes, the Lowthers are stunning, but your wallet screams for mercy whenever it hears their name mentioned...
Scott
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Old 4th August 2005, 10:28 PM   #12
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Is Bob's internal design the same then except for the foam?
Or has he tweaked the sizes of Martin's so there is a definite difference?
Seeing as I'm within budget on this one....yes you guessed it..
Are there any better drives that would be around that 200 budget?
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Old 4th August 2005, 10:45 PM   #13
Dumbass is offline Dumbass  British Antarctic Territory
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Quote:
Originally posted by Lostcause
Are there any better drives that would be around that 200 budget?
Probably not. The Fostex drivers are a great value.

Go to this page for Bob's discussion of and plans for a folded version of Martin's FE164/FE167E design:
http://www.geocities.com/rbrines1/Pages/Proposals.html
It models down to 40Hz, would be a right nice design IMO.

For stuffing I would just use polyester batting (from any fabric store) or [url=http://www.partsexpress.com/pe/showdetl.cfm?DID=7&Product_ID=5687]Acousta-stuf.

For a TL, airtightness and stuffing location/density are of the essence. The stuffing details should be tweaked to taste.

Regarding the FE206E/FE207E design, even if you don't use the BSC, you still need to put a series resistor in for proper tuning. Nice non-inductive resistors, however, are not expensive. It's the coils and boutique caps that get kind of pricey.
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Old 5th August 2005, 07:43 AM   #14
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Quote:
Originally posted by Lostcause
Is Bob's internal design the same then except for the foam?
Or has he tweaked the sizes of Martin's so there is a definite difference?
Seeing as I'm within budget on this one....yes you guessed it..
Are there any better drives that would be around that 200 budget?

No, it's quite different. There is a general relationship in terms of dimensions, as you'd expect, but Bob's are a more refined piece of engineering. They aren't based upon Martin's project you see: Martin simply licenced his MathCad software to Bob, who uses it to design from scratch (as do the rest of us MathCad types, but as a hobby) what are basically production speakers. That's not to say Martin's are poor however -quite the reverse. The fact that I've built two pairs will probably give you a good idea of how highly I rate them. For the price, I would go so far as to say they are the best speakers in the world in many respects. Bob's are a slightly more refined commercial product -he does this for a living remember, so they cost more as they are more complex to build.

Beware of external baffles etc. by the way. You can do unpleasent things to the sound quaility unless you are very careful. If you look at the gallery on Martin's site, you'll see plenty of FE206/7E MLTLs built to his design, and the driver looks quite at home.

Best
Scott
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Old 6th August 2005, 01:55 PM   #15
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Quote:
Beware of external baffles etc. by the way. You can do unpleasent things to the sound quaility unless you are very careful
That sounds a little worrying....Does that mean I have to follow the design exactly, with 3/4" ply and no more additions?
Bob's have a nice esthetic addition to the front, do you mean it is accounted for in the calculation, and the design does not work without it?
I'm asking because I thought I would break up the plain appearance and integrate it into our room by adding some laminates etc. (well bonded of course)
If I modelled it up (I am a 3D CAD engineer) could I put it through some sort of simulation (Ansys or something) to prove it?
Are Bob's superior then? (however slightly).
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Old 6th August 2005, 03:06 PM   #16
el`Ol is offline el`Ol  Germany
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I had very good results with the FE126E in the recommended horn/BR enclosure driven by the T-Amp. I don`t miss any bass, an 8" is not necessary.
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Old 6th August 2005, 03:32 PM   #17
Dumbass is offline Dumbass  British Antarctic Territory
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Quote:
Originally posted by Lostcause
That sounds a little worrying....Does that mean I have to follow the design exactly, with 3/4" ply and no more additions?
Bob's have a nice esthetic addition to the front, do you mean it is accounted for in the calculation, and the design does not work without it?
I'm asking because I thought I would break up the plain appearance and integrate it into our room by adding some laminates etc. (well bonded of course)
If I modelled it up (I am a 3D CAD engineer) could I put it through some sort of simulation (Ansys or something) to prove it?
Are Bob's superior then? (however slightly).
As long as inside dims are same, you will be fine. Just ensure that driver is securely mounted.
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Old 8th August 2005, 02:19 PM   #18
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Quote:
Originally posted by Scottmoose

Beware of external baffles etc. Scott
What did you mean by this Scott?
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Old 8th August 2005, 03:28 PM   #19
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Bob's are slightly superior designs; as I mentioned, Bob is the master at refining things. There won't be a huge amount in it however.And no, you won't have to stick with the plywood, MDF is just as good in this application; if anything, it'll be slightly superior in that it's less resonant and easier to work with. So you can cheerfully use this without problems.

External baffles are a bit of a problematic area, but not one you should really worry about with what you're planning, so go ahead with confidence.

The baffle, strictly speaking, is the front (and rear) panel of the speaker, but the word tends to be used to describe an external addition to this panel, like those oval shaped pieces attached to the front of Bob's (excellent looking) speakers. Those are there both for appearance, and because they provide worthwhile additional damping to the speaker cabinet. The major problems generally occur when people go too far, with wide baffles sticking out over the edges of the main speaker cabinet. That's when you run into diffraction issues. It's just something to be aware of really. Martin's site has a link to some baffle-step simulation software.
Best
Scott
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