New FE206E TQWT

[Scottmoose]

If anyone is looking for a new 8in speaker project, you could do a heck of a lot worse than checking this out guys: http://www.vitalstates.co.uk/ -click on the vofo tab. Ed's a friend of mine & there's some really good stuff on his site. As well as this project there's a write-up of an Ariel, and an Electrostatic build, plus plans for an adjustable mitre-jig available on request etc.

These folded 206 pipes are by a long way the best traditional type TQWT I've ever heard. In-room Clio response is also given on the page. It's basically flat to 50Hz in a smallish room -in a larger room it goes lower. I've run MathCad sims on this design as well. The in-room plots tally almost exactly with the measured response. If anyone's concerned about the slight peak at 200Hz, don't be, it's a room, not a speaker effect. They kick like mules, especially in the mid and upper bass. Punch and weight is superb, they do dynamics as well as some horns I can think of, and they've got a lovely throaty roar for rock. Imaging is razor-sharp -the lage radii combined with 206 clearly help here. Up top the 206 is as good on female vocals as you'd expect -no need for me to waffle on about that. Normally I wouldn't consider the 206 for a box speaker. I've changed my mind on hearing these. For the pretty minimal cost, it's a great project, and an interesting alternative to some of the other designs out there.

Regards
Scott

[freddi]

Hi Scott - do you think they might sound "similar" if built with flat/diagonal reflector at top and perhaps 1/4" pieces of sonotube for the bottom vent deflectors? My building friend got wore-out time-wise making one laminated curved reflector for a Karlson-type.

Freddy

[Scottmoose]

They should sound pretty similar. Ed is exceptionally good at building things, so he puts a lot into the fine details. The Sonotube idea is a good one -I like that. I suspect the curved ones will have a slight edge, but there probably won't be a great deal in it. One way to find out! The basic design is good enough to experiment with to your heart's content.

[freddi]

Hi Scott - so these are only about about 48 inches tall? - are the plans dimensions internal? What do you think would happened if bottom deflectors were omitted? Those distributed vents at the floor boundary might account for some of its magic. How might you describe its virtues vs a BLH 206 horn of similar bulk?

Freddy

[moray james]

Freddy & Scott: from a theoritical point of view the flat reflector should work more in your favor than curved ones. This is also the place where a layer of felt should also be of good use. With a curved reflector mid frequencies will have an easier time of making it around the bend. In this design where the terminus is deflected to the lower sides of the cabinet there is probably less issue of hearing the midrange output especially with the grate vent style used.
With front firing BLH considerable midrange output can be detected from the front mouth. This has a tendency to then alow you to localize midrange ftom the driver as well as the mouth so you get smear. Flat deflectors tenf to diffuse midrange more than smooth curved deflectors do. Best regards Moray James.

[Scottmoose]

Give or take. Dimensions are external I believe. I'd keep the bottom defletor in this case as the pipe is run over a wide passband.

Difficult to compare to a BLH as they're utterly different. Although TQWTs are notionally horns insofar as they are expanding lines, that's about it. It's smaller, the sound is not as massive as you'd get from a full-blown, well designed BLH (pretty big though), but it's far easier to build, and has more punch in the midbass regions. Goes lower for a given cabinet size too. A more natural comparison would be to an MLTL; though it has a flavour of both cabinets. Reminded me of a BIB actually in some aspects to the sound. Which is a good thing generally. I believe Ed got the idea for the vents from the Ariel V6c he built a while back.

[freddi]

Thanks Scott - I want really pretty performance on bowed and plucked bass viola plus some sock on drums and am used to limited LF but good load of Karlson type. (200-400W input peaks on a drum can be good with K)

Hi Moray - (flat reflector might work well in some Karlson? )
what do you think about the curved routing pieces for Vofo's vents? - is there a viable option to simplify or might attempts ruin the design?

(Bill's Fulmer/Karlson-slot BLH might not have a lot of HF leakage ?)

Freddy

[moray james]

would be to use round wooden dowles or you could edge shape vertical rectangular wood pieces to amount to the same configuration. Don't think it would make a lot of difference as long as you keep the open area in the same ballpark. Regards Moray James.

[freddi]

Scott - is there an impedance curve available of the Vofo ? (did I overlook one?) how were the vent's proper area figured? with MJK's sheets? - a modeling program? - "experience"?

Moray - this is a pretty cabinet. I wish the Karlson builders (all two or three - if that many? - out of 6.6 billion people would kome out of the woodwork - there is a page to be found under "Carlson-coupler" which has a cryptic calculator.

Freddy

[Scottmoose]

Originally posted by moray james
Freddy & Scott: from a theoritical point of view the flat reflector should work more in your favor than curved ones. This is also the place where a layer of felt should also be of good use. With a curved reflector mid frequencies will have an easier time of making it around the bend. In this design where the terminus is deflected to the lower sides of the cabinet there is probably less issue of hearing the midrange output especially with the grate vent style used.
With front firing BLH considerable midrange output can be detected from the front mouth. This has a tendency to then alow you to localize midrange ftom the driver as well as the mouth so you get smear. Flat deflectors tenf to diffuse midrange more than smooth curved deflectors do. Best regards Moray James.

Yeah I know. That's why I always advise people not to put deflectors in a BIB. I suspect the construction Ed's used for the curves, with the loght ply and the compressed foam helps damp someof it, and the mild mass loading of the terminus (vent CSA=82% of Sl) filters it, especially as they vent sideways, as you note. The Clio chart indicates it's flat to 1KHz, ignoring the blip caused by a room mode at 200Hz. It's a fairly wide passband design by nature though, so if we're accepting some HF / midrange leakage, as we do with, say, a BIB, or other types of horn, it's as well to make it as smooth as possible! Ed stuffs the first half of the line, and a layer over the bottom deflector. I'm not sure if he's put any around the top -if not, probably a good tweak to experiment with as that's where we usually put a layer in a BIB (well, the other way around, but you kow what I mean!). As always, YMMV. My apolgies BTW -I somehow missed your post earlier.

MathCad generated impedence trace attached. Not bad at all for a TQWT. Using a Karlson instead of the multiple side vents could be a fantastic variation on the idea. What I love about this design is that the basics are nicely refined, but being a large TQWT, they leave plenty of scope for people to experiment with their own variations on the theme.