Fe167e Br

regal

Member
2004-01-04 8:41 pm
MD
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?
 
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.
 
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.
 

Bob Brines

Member
2003-01-31 10:11 pm
regal said:
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
 
Bob Brines said:
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?
 

regal

Member
2004-01-04 8:41 pm
MD
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)?
 
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
 

Bob Brines

Member
2003-01-31 10:11 pm
Dumbass said:
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.

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.

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.

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.

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
 

Bob Brines

Member
2003-01-31 10:11 pm
regal said:
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)?

How do you intend to do the cross-over? At these low frequencies, an active XO or DSP is required.

A Fostex FE167E in a 25 liter BR will have f3 ~60Hz. Alone it is good to ~50Hz with doubling below that. You will "hear" down to 40Hz, but it is faked and sounds funny. Alone, it will not play loud without serious distortion. IMO, you must cross it no lower than 100Hz.

A Fostex FE167E in a proper MLTL is good to 40Hz stand-alone. The bottom end is a little soft, but very listenable for acoustic instruments. Anything but 5-string bass guitar, C-extended double bass and organ. However, running the MLTL full-range but crossing in a sub a 40Hz gives you a new experience. The low acoustic range is much firmer and you can go as low as the sub allows.

IMO, given a proper active cross-over, BR's and subs will give a cleaner sound because of reduced IM distortion and greater overal SPL. If you are going to run the mains full-range, then go with the MLTL. This also gives you the option of much better balance when running without a sub.

Bob
 

regal

Member
2004-01-04 8:41 pm
MD
I plan on using the active crossover from my reciever unfortunately it is set at 80hz.

Funny a previous post metnioned Led Zeppelin, I do intend on listening to Led. I am willing to give up some loudness. I am still in awe at the way a guitar sounds on the 127E's
 
AudioGeek said:
i think on the second post there was a link to a FE167e ML TQWT design which is folded.
does this design have BSC and if not what would be a good starting point?
Martin's Project 2 BSC would be a good place to start:
http://www.quarter-wave.com/Project02/Project02.html
Recall that Bob's design is simply a folded version of Project 2. If you want to "roll your own" or simply double-check the values, he has a generic article on calculating component values:
http://www.quarter-wave.com/General/BSC_Sizing.pdf
AudioGeek said:
i have a pair of 167's and unsure which way to go.
BR for simpleness or the TQWT way...
IMO the TQWT isn't considerably more complex to build. It is, of course, considerably more voluminous and also more difficult to design.
 

regal

Member
2004-01-04 8:41 pm
MD
Re: fe167e folded ml tqwt

AudioGeek said:
i think on the second post there was a link to a FE167e ML TQWT design which is folded.

does this design have BSC and if not what would be a good starting point?

i have a pair of 167's and unsure which way to go.

BR for simpleness or the TQWT way...


If you are woodworking challenged like me a BR + sub is the way to go. By highpassing the BR you also have the advantage of greater power handling and clearer midrange vs a TL
 
planet10 said:
If used with a sub, the box ideally should be sealed or aperiodic. A BR can be made aperiodic by stuffing the port.
Or sealed by completely plugging it up!

You make an excellent point. With stereo 10" drivers, shouldn't be too hard to integrate them, they ought to go up plenty high enough. If you're already putting in a bi-amped woofer, why bother with venting the full-ranger?

In fact, this system is exactly the proposal given by Doc Bottlehead and Paul Joppa (except they choose the FE166E driver, should work even better with FE167E):
http://www.bottlehead.com/loosep/S.E.Xy speakers.html
 

regal

Member
2004-01-04 8:41 pm
MD
If you go sealed with the 167E's then you have to cross in the subs at 150hz. This is probably too high to be mono. To go stereo on the subs you have to have a separate active crossover. Recievers only have a mono sub output.

I have found that you still need BSC because the bass drops off from the BS starting around 200hz.

I would be interested to know if a passive crossover would work, it would probably be expensive with the size of the components and you would need a sub that could play pretty high because the xover couldn't be as steep as with an active xover.