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Old 23rd October 2007, 06:50 PM   #1
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Default Newbe questions TQWT using fostex FE206E

After spending some time surfing around, looking for a fullrange speaker I was ending up with more questions than answers. I did find som nice ones like the metronome, Fostex FE207 voigt pipe, BIB and some others. But when I did have a look on the speaker data for the FE207E it started to roll of at 12kHz so that one would problary need a tweeter. When sjekking the FE167E i noticed that it Fs was 51.1 Hz so this one would need a subwoofer in addition. So i did have a look at the FE206E it went from 39 Hz to ca 20 kHz so this one looks promising. The only problem i could se was the rising SPL from around 1.5 KHz. And with a Qts of .18 i did gues it was made for horns and not for a TQWT :-(

So after searchng a bit on the web again i did find the vofo, using the FE206E and acording to the builder it sounded good. So what is the secret, i was reading about people trying to use it in a voight horn and it was no god. Is the trick the mass loading/volume or is there somtning else? So is this the cabinet to build or is there somthing else i should go for?

I did notice that this speaker did have an SD=0 and i did read somewhere that this was not recommened.

Basicly what I am asking for is what element to use and what enclosure i should use. ( i like them narrow and tall insted of low and wide)

The amp i am currently usin is a Pass A-40 But i would like to try out one of those T-Amps in the future. have been looking at some from 41Hz.com
The music i am listning to is almost everything. from classic to rock.

Sorry for my bad english
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Old 23rd October 2007, 08:01 PM   #2
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Nothing wrong with your English.

Ah, the old So=0 thing. Actually, all it does is provide the maximum possible pipe-gain over the widest possible passband. It's harder to design an So=0 pipe, but they ultimately have the edge over a trunkated one IMO, assuming both are designed correctly. They need to be longer than a trunkated pipe though -the smaller the 'throat' CSA, the longer the pipe needs to be, just like horns.

I've actually got Ed's MK2 Vofos temporarily (swapped them for my MLTLs which he wanted to measure) -I'm listening to them now, and very good they are too. He's balanced the length, Vb, driver location and vent positions / CSA very well indeed to suit the 206. So if you want a reasonably sized floorstander for the 206, they're a good option.

No back-loaded cabinet can do much about the 206s rising response, though a very long horn (hyperbolic or catenoid) will pull it down a bit. However, it doesn't seem to be too much of a problem. If things are a little too hot, you can add phase plugs, which tame it, damp the basket & magnet which further pulls it into line, and add some series resistance, or a shelving filter and / or zobel if you like. Better to have a high-power motor IMO -you can always loose something you have too much of.
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Old 24th October 2007, 07:20 PM   #3
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Thank you for the answer. I guess i will give the vofos a try :-)
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Old 24th October 2007, 08:33 PM   #4
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An alternative is Martin King's MLTL: http://www.quarter-wave.com/Project05/Project05.html

Normally, I prefer MLTLs over TQWT, but the Vofo really does work very well indeed with the 206 & will need less correction in this box, so this is my exception.
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Old 25th October 2007, 07:35 AM   #5
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Is there any reason that you prefer MLTL over TQWT? I am looking for a project that is pretty easy since this is my first experience with fullrange speakers, but if Mr. Kings design is a better solution then i might go for that one.

What I am looking for is a speaker with good imaging, god sounding and dynamic.
To put it another way, if you were to build a new speaker using one of the fostex fullrange speakers (or another element in the same price range) , what element and cabinet would you select to achive the best result.

I was reading about the EnABL process ( keept me up until 3 o´clock this night :-) interesting reading) an this might somthing i want to try with the elements. Have you tried this one? or lisened to any speakers who are EnABL.
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Old 25th October 2007, 09:01 AM   #6
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See the comment I made above. I think that it answered your question.

Quote:
Originally posted by Scottmoose
Normally, I prefer MLTLs over TQWT, but the Vofo really does work very well indeed with the 206 & it will need less correction in this box, so this is my exception.
Normally I do prefer MLTLs. The Vofo with the 206 is an exception. The 206 needs less correction in a TQWT than a straight mass-loaded line, which is fine with me.

What would I do? Depends how big the room is, where the speakers are positioned, how big a cabinet I can stomach, what I listen to & what the rest of the system is like. There's an infinite number of combinations, because there's no real 'best' -all design is a compromise. Fs isn't especially useful as a measure of how low a speaker system will go BTW -my 167 MLTLs are designed for (and achive) an easy 40Hz in-room, so don't let that put you off. Where larger drivers really score over smaller ones is in a large space, where the greater cone area means they shift more air, though they sacrifice some fine detail & imaging to get it (not that they're lacking on the detail & imaging front themselves).

If you can cope with a tall box, & you've got corners, or at least a rear-wall to load them with, I'd be inclinded to build a BIB pipe-horn, preferably with an 8in driver like the 206 (that'd be big though) or more reasonably, the FE168ESigma, or FF165K. Tall, reasonable footprint. It will kill the same driver in a smaller cabinet stone-dead in the LF & gives a very spacious presentation. There's a little more ripple than some, but not that much, and most people don't find it bothers them. One of my all-time favourite cabinet types for FR units. see www.zillaspeak.com/bib.asp If you can't cope with the height, the Vofo's as good as any other simple build (& better than a lot), assumining the 206 is selected. But there are literally hundreds of designs around, some complicated, some relatively simple, so have a browse around the forum.

No, I haven't tried EnABL yet -I'll be applying it to my 126s & 167s when I'm able to, out of interest.
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Old 25th October 2007, 05:21 PM   #7
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I guess the 206 is out of the question when using a BIB since the hight in my room is only 87 inches (220 cm) unless I use the shortened BIB (140") or the FE167E (136"). Hmm guess i have to search bit more on the web.
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Old 30th October 2007, 03:02 PM   #8
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Default For first project must you use the Fostex?

Interesting project. I too am searching for a like project however I already have one pair of AudioNirvana Super 8s that I want to use. They work well in a bass reflex design in which it was provided and have much potential too. I think they will perform better in a horn design though.

I have already looked at the saxophon design (http://www.hm-moreart.de/) but this is too large (pessimistic wife factor) and difficult to build. I was considering the Voight Pipes that are from Miller's site. They are already designed for the Lowther so only minor modifications I believe will be necessary. I would like to avoid correcting with signal and prefer to do this mechanically if possible.

I think I have paid about €250 for the pair 8" with shipping to Italy. The cabinets will not cost very much. so maybe less than €350 you can possible have a nice pair.

The Saxophon model is very interesting but difficult to build.

BG,
MV
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Old 30th October 2007, 03:27 PM   #9
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Miller Voigt (no 'h': P.G.A.H. Voigt you know, not that he had anything to do with them ) Pipe? Haven't heard of that one before.

If you're talking about the Lowther Club of Norway 'Voigt Pipe' I strongly advise you not to try it. Nominally designed for the Lowther PM6c they might have been, but they're not up to much at all. Response is ragged & cut-off is needlessly high -you won't be getting anything extra out of them than your existing (sub-optimal) BR cabinets. If you want a simple build, I'd suggest you look at a BIB instead, which is even easier, and you'll get much better performance.

WRT not wanting any electrical correction, only mechanical, something like the BIB can use its own gain to compensate for baffle step loss (all cabinets suffer from this) but no back-loaded cabinet can correct for the ANS8's rising response by itself. It can help in the LF, but note that above ~500Hz, it continues to rise until peaking at roughly 14KHz, 15db over the driver's nominal sensitivity figure. The only way you will get that into line is either with an electrical shelving filter, or adding another driver & rolling it off above, oh, about 2KHz or so (Horst does something similar I believe).
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