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Old 9th August 2005, 11:36 PM   #1
regal is offline regal  United States
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Default Fe167e Br

BR 167E

I built a pair of the standard BR (not double) for the fostex 127E. I absolutely love the way the speakers reproduce the guitar and image. I want to build another pair of speakers with these qualities but with better midbass and bass. This time I plan on including a sub for 80hz and below.

What are the thoughts of the 167E with the above enclosure?
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Old 10th August 2005, 12:02 AM   #2
Dumbass is offline Dumbass  British Antarctic Territory
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If you are going to build a floorstander, why not build this design:
Folded ML for Fostex FE164/167E
which is simply a folded version of this one:
Fostex FE-164 in a ML TQWT Project

I think that Fostex design is kind of nifty, but the TL enclosure ought to give you deeper and better bass than a simple BR. They model flat down to roughly 40Hz, so integrating with a sub ought to be pretty simple.

I have read nice things about the FE167E. I myself use FE207E drivers in BR enclosures, I like how they sound. The 167 ought to give slightly nicer high-end, this is what people say subjectively and also if you compare the published freq-response curves.
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Old 10th August 2005, 08:21 AM   #3
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Forget BR designs if possible; a properly designed TL is always more versatile.

It's a pity Bob has removed most of the basic designs from his site, leaving only his old projects and ideas there. I don't blame him though as he has to make money! The folded version of Martin's ML TQWT that he still has on his site is worth using however: I've built several pairs of Martin's design as it stands, using the 167, and loved them. A single fold won't make any difference to the sound.
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Old 10th August 2005, 03:11 PM   #4
regal is offline regal  United States
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Does it make sense to do a TL if using a sub? Looks like the BR enclosure is pretty flat at 80hz.
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Old 10th August 2005, 09:26 PM   #5
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Quote:
Originally posted by regal
Does it make sense to do a TL if using a sub? Looks like the BR enclosure is pretty flat at 80hz.
Well, yes it does. If you are going to use a sub, then you are for all practical purposes designing a two-way speaker. With any two-way, is would be nice to have a couple of octaves overlap in the cross-over region. This means that if your TL goes south at 40Hz, you should be considering your cross-over at 160Hz! Of course, at these low frequencies, a passive cross-over is is hard/expensive to do, so you go active or digital. An HT receiver is a good solution.

In reality, tough, A quarter-wave resonator with f3 of 40Hz can be run without a cross-over without much worry about over excursion. A BR with f3 of 60-80 cannot. So.... I run my MLTL's full range with a sub crossed at 40Hz but cross my BR's at 100Hz through the HT receiver.

Bob
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Old 10th August 2005, 09:57 PM   #6
Dumbass is offline Dumbass  British Antarctic Territory
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Quote:
Originally posted by Bob Brines
In reality, tough, A quarter-wave resonator with f3 of 40Hz can be run without a cross-over without much worry about over excursion. A BR with f3 of 60-80 cannot. So.... I run my MLTL's full range with a sub crossed at 40Hz but cross my BR's at 100Hz through the HT receiver.
Bob, what is drop-off of MLTL? 2nd order? (I believe it's in between what a BR has and what a straight TL has, right?)

If you have 167 in BR, it starts tailing off at 80Hz. So you need to run it full-range, and get into excursion/boominess problems like you said.

Do you ever add, say, a first-order high-pass to 167 MLTL to steepen the natural drop-off curve?

Now that we have reliable computer models for TLs, it seems unnecessary to use simple BRs for drivers like this, unless space is an issue.

P.S. Next time my wife and I visit her grandmother in Hot Springs Village, would you be willing to audition some of your stuff?
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Old 10th August 2005, 11:07 PM   #7
joensd is offline joensd  Germany
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Quote:
If you have 167 in BR, it starts tailing off at 80Hz.
In the 15l recommended it already does so at 100Hz if you believe simulations.
Even if you plan in a sub IŽd go with ~25l net volume similar to the FB-16 or the omega-loudspeakers.
http://www.geocities.com/rbrines1/Pages/FB-16/Main.html
http://www.omegaloudspeakers.com/
Just tried it today (15l recommended) with a sub and even then I wished the "satellites" would have more bass to make crossing over easier.

greets
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Old 11th August 2005, 12:33 AM   #8
regal is offline regal  United States
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I mainly listen to blues and guitar rock prefering classic sealed 3 ways. Having just built a 127E BR for my daughter I was amazed at the clarity and imaging of the way the electric guitar and vocals are delivered.

So it would be better to use Bob's MLTL full range with a sub at 40hz
instead of the BR high passed at 80hz (sub low passed 80hz)?
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Old 11th August 2005, 07:50 AM   #9
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Yes.
Bob's FT1600MK2 will be wonderful for acoustic blues (or any acoustic or vocal-heavy music come to that). Partnered with a sub, you won't get much better for the money. In fact, I don't think you'd get better for the money, period.
However, when you say guitar rock, how heavy are we talking here? Led Zep style? If so, while it can do it, expecially when partnered with a sub, it might not be quite ideal; they weren't designed for rock. They can do it of course, and are surprisingly adept, but do have certain loudness limits -there's only so much air you can move with a 6" driver after all, and you might want to think about moving to 8" units. Bob has several larger designs using 8" Fostex and Lowther units too.
Cheers
Scott
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Old 11th August 2005, 09:05 AM   #10
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Quote:
Originally posted by Dumbass
Bob, what is drop-off of MLTL? 2nd order? (I believe it's in between what a BR has and what a straight TL has, right?)
An MLTL is a resonant cabinet. The port response rolls off 2nd order like a BR and the driver rolls off 2nd order giving an overall roll off of 4th order. If there is any port output from a "straight" TL, it will also roll off 4th order, albeit at a rather low Q.

Quote:
If you have 167 in BR, it starts tailing off at 80Hz. So you need to run it full-range, and get into excursion/boominess problems like you said.
Remember that with a resonant cabinet, you run out of excurion 1/2 octave above f3. Whether the speaker is boomy depends on the shape of the high-pass tail. The Fostex 15 liter BR is designed with a strong peak at cutoff, presumably to eliminate the need for a baffle step correction filter. But this means you need to cross it over before that, at least by 100 Hz. It is strictly an HT speaker.

Quote:
Do you ever add, say, a first-order high-pass to 167 MLTL to steepen the natural drop-off curve?
First of all can you imagine the size of the cap you would need at 40 Hz? Secondly, you want to have the high-pass tail exactly compliment room gain. Ideally, you want somthing far less than the natural 24dB/octave roll-off of an MLTL.

Quote:
Now that we have reliable computer models for TLs, it seems unnecessary to use simple BRs for drivers like this, unless space is an issue.
This all depends on the driver chosen and the goals to be obtained. My FB-16 BR and FT-1600 MLTL, both using the Fostex FE167E, have the same footprint, but the BR is half as tall.

Quote:
P.S. Next time my wife and I visit her grandmother in Hot Springs Village, would you be willing to audition some of your stuff?
Give me some decent lead time. I am "retired", so my life is not very structured. But sure, drop on by.

Bob
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