[JLM]

IMO, the Principles:

It must emulate as much as possible the single point source ideal.

Any good speaker must cover the entire audible range of the source.

A near perfect speaker must allow for playback at peak concert levels.

It must also produce a large and accurate 3 dimensional image and therefore cannot be built into the walls of the room or be designed for placement against walls.

The cabinet itself must be inert.

A cone driver using a whizzer cone is not to be confused with a single driver.


Application:

I can’t imagine putting this all into perfect reality will never come to pass, but thanks to Fostex and Bob Brines I now own the closest theoretical solution that I’ve found to address the above principles.  Using Fostex F200A drivers (30 – 20,000 Hz, minimum 8 ohms impedance, 90 dB/w/m, 80 watts peak input) Bob has designed and built floor standing mass loaded transmission line (MLTL) cabinets that extends this already impressive performance.  The “classic” advantages of MLTL cabinets are improved bass extension and virtual elimination of back-wave reflections through the cone.  Properly designed, the bass roll-off is gradual that “tricks” the ear into augmenting to “provide” a flat/extended response.  With a driver of this size and f3 this low the MLTL can be designed to emulate an infinite baffle (complete removal of the backwave) but with dampening characteristics (to provide higher efficiency).

The drivers aren’t cheap, but cost less than exotic “full range” drivers.  The cabinets are very heavy and rigid (bracing, double walled construction with     ening material added).  With baffle step compensation and careful stuffing of the TL the speaker produces a very flat response without cabinet colorations and the design eliminates out of phase signals.  In room on-axis response is essentially 25 – 20,000 Hz, with peaks reaching 107 dB (with 80 wpc inputs) in a 2,000 cubic foot room without a whizzer.  Bob believes in flat frequency response (which the design and fiber fill allows for) and he has also provided a baffle step compensation circuit.  Purists may gasp at the thought of electronics added to a speaker, especially a single driver concept but plenty of circuits already exist in the overall audio playback chain.


Initial Observations:

Break in of these drivers is measured in the hundreds of hours, as are many other good extended range drivers.  I picked up the speakers with reportedly 250 hours already on them.  After 4 days laying on their sides in a trailer, bouncing 900 miles home and “resting” for a day I connected them to my Rotel 100 wpc receiver and Sony XA20ES CD player.  My first impression was thick and muddy.  Please note that due to current room and domestic restraints the speakers spend most their time almost tight against the walls of my 11 ft x 19 ft x 8 ft room with CD storage cabinet and equipment between them.  The bass was boomy with efficiency only appearing to be around 85 dB/w/m.  Beaming of highs was quite evident.  They didn’t seem very dynamic.  Volume levels seemed to “sneak” up the longer the listening sessions continued.  Thankfully they did not “show the warts” of poor recordings too badly.  Bass did not image (a trait of break-in according to users of the F200A’s smaller brother, the Fostex F120A driver).  But depth of recording venue shows up very well.  Detailing is good and I’m hearing parts of familiar recordings not experienced before.

The beaming was expected, but should not be an issue with nearfield listening.  The boomy bass was also expected with the current set-up, hopefully some experimentation will prove this to simply be a matter of placement.  And the bass imaging should also go away.  But the undynamic, inefficient behavior of the speakers is disturbing.  Having briefly heard them at Bob’s place with completely unremarkable ancillary equipment (a sign of “real” speaker guy) I’m sure they’ll improve greatly.  And I need to get detailed “care and feeding” instructions from Bob, as he suggested changing resistor values on the baffle step circuit as the drivers continue to break in.  

After 2 days and a 3 hours of continuous playing each day I’m finally hearing a very nice amount of sparkle from triangles!  These speakers (against the wall still) are bass animals on Holst’ Planets.  And dynamics seem to have improved as well.  Over the following weekend I pulled out the speakers a reasonable distance from walls and arranged them in a 68 inch equilateral triangle to my chair.  I listened to a rather wide variety of music and at moderate to fairly loud levels. Bass extension/output was unusual in that it seemed full, deep, and musical but lacked a degree of “boom” or apparent energy (blow the pant legs sort of thing) that nearly every “full” bass design (including my previous speakers) exhibit.  This is exactly the predicted slow roll-off bass augmentation effect and should help minimize room energy loading associated problems.   The speakers sounded very good indeed.  Mid-range seemed very natural, highs were clear and imaging was pin-point.  Compared to speakers based on most extended range drivers the response was certainly tilted toward the bass end.  Compared to multi-driver speakers the sound is much more coherent but admittedly lacks a bit extension at each end compared to many of the more elaborate designs.  However much of that extension can be considered “hi-fi hype” and not accurate or essential to listening enjoyment.

After listening to them for two weeks at home the only aspect of their performance found lacking is life like dynamics.  This is too much to ask of 90 dB/w/m drivers.


A few more details:

These speakers were a custom commission.  I approached Bob with the idea of applying his knowledge of MLTLs with his craftsmanship to use of the Fostex F200A.  The speakers are 48 inches tall, 14 inches wide, and 16 inches deep, with the driver centered 33 inches above the floor.  The line starts at the top/front of the cabinet 15 inches beyond the center of the driver and makes a 180 degree turn before terminating about 3/4 of the way up the back side.  The panels around the driver are double thickness and braced with dowels producing a weight per cabinet in at about 70 pounds each.  Note that the F200A weighs 10 pounds each with 2 pound magnets and 3/8 inch cast aluminum frame.  They are finished in quarter sawn cherry veneer and cost about $1,500 USD.

Bob was satisfied enough with the speakers that he was considering to add them to his web site as his third speaker offering, unfortunately he has heard that the Fostex F120A and F200A alnico drivers may be discountined soon.  If he builds more he wouldn't finish the back side around the tube mouth (to much of a PIA).  Between that and the savings from using less costly veneers he might knock off $100.  

Wifey just got a digital camera package and as soon as we figure it out I'll try to post pictures.

Note that the baffle step circuit (BSC) takes 2 dB from the rated efficiency, so it's down around 88 dB/w/m.  OTOH it should be a very easy load as the MLTL evens out the bass impedance hump.

Bob's website:  http://www.geocities.com/rbrines1/  

Yes, some settling of the stuffing may have occured during shipping, and I've read of lumping as something to be avoided.  I'll have to take a look.  BTW Bob used very little stuffing (just enough to even out the frequency response), in fact the back fold of the line has no stuffing at all.  Final tweaking (resistor change and permanent mounting of the BSC and permanent wiring of the speaker) won't occur until they are properly nested in my new listening room (about June 2005).

[TheChairGuy]

Wonderful new speaker set-up JLM....do leave us some pics and further impressions as they break in. Very promising they seem to be.....

[Dmason]

Nice write up JLM, gives good insight into the design.

I have a pair of AlNiCo 200A's on the way. I did hear they will likely be discontinued, at least for distribution in North America, which was a major factor in my decision to get some.I will be using them to start, in a 25L BR cabinet, which, admittedly is less than optimal, but nonetheless will be a good home for them.

From what I have read on the F200A, they take sooo long to break in that probably there isn't much point in coming to any conclusions good or bad before about six months of fairly regular play. They evidently take far longer than about any other speaker out there. So, the start is a fine one, indeed. The 200A is quite a dynamic speaker once fully "matured,"  from the stories of others.

Martin King's mass loaded transmission designs have been univerally praised. There is a good review of your cabinet with the Lowther DX I believe on www.tnt-audio.com The Fostex F200A are a bargain compared to even the bottom of the line Lowthers at about $1300 a pair.  

[Scott F.]

Martin King's mass loaded transmission designs have been univerally praised. There is a good review of your cabinet with the Lowther DX I believe on www.tnt-audio.com The Fostex F200A are a bargain compared to even the bottom of the line Lowthers at about $1300 a pair.

Hiya Dmason,

Actually the drivers I use are the PM2As. Jon VerHalen recently had to raise the price due to the US $ getting pounded abroad. The PM2As have gone up to $1575 a pair.  

Granted, these ain't cheap, roll in the fact that the Medallions I run are another $750 unfinished from a local cabinet maker but when you consider the cost of a typical high end 'monkey coffin', it doesn't seem quite as painful.

On the DIY side, Martins MLTL sounded (in certain aspects, bass primarily) better than the Medallions. As I mentioned to Martin and others, I didn't stay with the MLTL's because I'm only running 2.5wpc. The notch filter (as JLM mentioned) takes about 2-3db away from the speakers. When you start with 2.5 watts, there is nowhere to go but down regarding final SPLs and adding filters.

One of these days I plan on buying a pair of 208E's to stuff into the MLTLs. That sound should be a lot of fun.

Oh, and I know, single driver, high efficiency speakers aren't just for fleapowered  SET's. I got beat over the head with that one plenty after that review got published

Heres the link
http://www.tnt-audio.com/casse/lowtherpm2a_e.html

[JLM]

After another couple of weeks of use, the F200A MLTLs are continuing to become more dynamic (micro and macro) and additional mid/high frequency details are being revealed.  I'm having to re-assess which of my recordings are "audiophile grade" as new life is discovered in them.  And they're still gaining efficiency the longer they're left on per session, maybe 8 dB in the first 30 minutes and a bit more afterward that.

The break-in has gone from being a worry at times to rather fun.

[JLM]

Two weeks more time put on the speakers and they're sounding better everyday.

My speakers now have a name:  FTA-2000

See them here:  http://www.geocities.com/rbrines1/

[mcgsxr]

Any line on where to find the drivers themselves?  Weren't they discontinued?  Oh, maybe that was the more affordable FX200.

mark

[gonefishin]

Hi JLM...sounds like you've got some nice speakers breakin' in.  So far, my favorite single driver is the pm2a Medallions, but I really can't afford the drivers.  

   Maybe one of these days I'll try a Fostex project...I'll certainly be looking foward to hear anything you've got to say about your new speakers.

  congrats!

[JLM]

I bought the F200A drivers from Madisound last spring.  They had them in stock, no problem.  Nice folks to deal with.  I've heard that Fostex may stop importing them to the U.S., but am no longer in the market.


I haven't done tons of serious listening as my current room set up is laughable and I've been very busy (in part due to trying to get construction for a new bigger house, with dedicated listening room started).  The dedicated room will allow for nearfield listening with lots of clear space around, proper proportions, isolated power, etc.  As I go through my collection I continue to find new detail or deeper bass than I remembered.  Wifey mentioned the other day that they were sounding good.  (Always a plus, not that I really understand what she means by that.)  

I've listened to I. M. Fried MLTL speakers for the past 25 years, so much of what I'm hearing is very familar, nothing like typical punny single driver speakers with no bass.  But the bass is somehow different from anything I've heard before.  The depth of bass stuns me from time to time, but the volume of it can be less than expected for the given depth.  I did some very quick measurements using a RS spl meter and Stereophile test CDs a few weeks ago, but came to no real conclusion as I figure that they're still breaking in and even with moving furniture around the setup was still less than ideal.  Midrange continues to improve (more open, more detail).  At 48 I'm not missing the treble sparkle that a supertweeter could add, espeicially when seated on axis.  And I know that my 5 year old Rotel stereo receiver and Sony XA20ES CD player aren't up to the challenge.

Overall break-in is offering a very fun ride.

[mcgsxr]

It is great to hear from a satisfied customer, who so well conveys what they like about what they have - nice series of posts.

Mark in Canada

[JLM]

Last weekend a couple of friends from the Decware forum came over with some of their stuff and spent the day.  Driving my FTA-2000 was a 3/7 wpc integrated tube amp (SE34I) and a 12 wpc tube integrated amp (Torii).  Each sells for about $1,500 depending on configuration.  The original SE34I (now updated) offers two different output circuits via each pair of EL34 tubes that can each be run separately or combined in series or parallel for tons of flexibility.  The Torii is a dual mono SET/push-pull crossover sort of design.  Both sound similar, but my vote with these speakers is the Torii.

The numbers say otherwise, but the Torii offered all the volume I need and has raised the bar significantly compared to the 6 year old 100 wpc Rotel I own.  Resolution in improved, dynamics are greater, imaging can be spooky good (the amp is still breaking in after recent updates) and bass is much more solid.  Unfortunately the Torii is only on loan, but the good news is that Decware offers a power amp only version and a high output tube pre-amp for only $300 more combined ($1,800) than the integrated version that reportedly makes a huge improvement.

I'm reporting all this to let folks know that a 90 dB efficiency single driver speaker (we took the baffle step circuit out with good results that had been costing 2 dB) can be a surprisely easy load to drive.  I'm sure the MLTL cabinet (that smooths/flattens out the bass impedence curve) helps.  Single driver speakers rule.    

[mcgsxr]

Have you had the chance to hear a digital amp on these speakers?  I know that there are many advocates of this combination around here, and would be interested to hear your thoughts, if you get the chance.

mark in Canada

[Dmason]

I am using the JVC F10 with the AlNiCo Fostex 200A. Startling is the word with the DSP x-over in the receiver, and the sub out to a VBT sub to reduce the excursion of the Fostex. All I can say is that digital amps with singles are a conversion on the road to Damascus for me. I cannot imagine what JLM's outfit might sound like with a nice digital amp on it.

I  recently built a pair of Voight pipes for the Jordan JX92S, which is working equally well, within its limitations. For vocal and instrumental music, the Jordan pipe is pretty hard to beat in any way at any cost. The amount of bass wrung from this design is hard to square with what's going on. The 92 is the culmination of forty years of effort   by Ted Jordan, jolly country squire and speaker guru, at his lab in Exeter. The legendary Goodmans Axiom were Ted's design, in the early sixties, and the very first  use of thin metal diaphragms.

[JLM]

Mark,

I'd really like to try a digital receiver as I could always use it to create a HT system if it didn't pan out (as a very good audio only amp).  But we're trying to build a house starting yet this fall, so finances and time are both at a premium.

DMason,

Please excuse me for not reading 30 pages of posts, but does the JVC F10 allow for 5.1 HT (as our room lays out with the screen on the wide wall and 5.1 would seem to work the best)?

[Bemopti123]

What is the lowest powered tubed amp you have used with these speakers?  I have a 300B SET amp that puts out 9 watts per channel as well as a DC powered 10 watts per channel SS amplifier, that was measured to about 17 watts until clipping and I wonder whether both would be decent matches to these speaker.

What is the purpose of the face part being oval and raised?

[Dmason]

JLM;

 the F10 is actually 6.1.  The RX-ES1 is 5.1, otherwise, they seem to be identical internally. You could quite easily do surround in the new place using Brines Boppers as mains, and small Fostices in small boxes from PartsExpress. OR, think about the little Jordan JX53, which would be ideal, in their small sealed boxes, designed to be wall mounted.

The HT implementation in these JVC's is pretty good in my totally inexperienced opinion on the matter, but I do know that it uses a high speed Motorola chip for all that stuff, and it also has a couple of really nice, useable reverb tails, handy for adding some wetness to some of the older stuff, or as I use it for some rather dry, acoustic recordings.

[mcgsxr]

JLM, I can totally understand not wanting to pop for pricey gear, if it won't do the trick.  I just sent tvyankee some $$ for the RX-ES1 that he was selling, it should be here in a couple of weeks.  It is affordable, and can do the 5.1 you might seek.

Also, there are a number of people who are combining the Teac $99 digital amp that I have 2 of, with speakers similar to yours - single driver, no Xover etc.

I just put an order into CSS for a pair of their little 4.5 inch full rangers (since the Fostex FX200 is discontinued, and the Jordan JX92S is on back order...) so I will let you know what the baby Teac does with those, once I build them out.

Oh, and I will report on how the Bolder Cable modded Teac sounds too...

Just a thought for you, since so many Omega and Horn Shoppe people are pleased with the cheap (well below affordable...) tripath combinations out there.

In the end, give them an ear if you can, but buy what turns your crank, just like those speakers do!

Good luck,

Mark in Canada

[JLM]

Bemo,

We tried a 3 wpc EL34 amp and it did O.K., YMMV.  I won't get into the tube watts versus solid state watts discussion.  Your 300B should do fine if you're not a in a large room or like to really       it.  With the 12 wpc Torii satisfying background levels start at 8:00 on the volume control (7:00 is zero volume), serious auditioning would be about 9:00, 12:00 is as loud as I'd ever want (and it goes up to 5:00).

The black oval is additional baffle reinforcement, allows for additional room to fit the driver in front of the slanted partition that defines the tapered transmission line, and is Bob Brines signature styling.  He offered to do something different, but I honestly couldn't think of anything else that would reinforce, be at least the size of the driver, and look better.


DMason,

Not interested in using the FTA-2000 for HT, they will be safely kept in my locked stereo listening room.  I'll probably just add to my existing 2.1 HT system with additional Ascend Acoustics speakers (great for the price, too good for HT IMO).  HT is a low priority to me, so I'm sure the JVC would be plenty good enough.


Mark,

This set-up will be a nearly no compromise system, so I don't want just a great for the price solution, but a near great at any price solution or great at any reasonable price solution.  The HT is for family use and must be very user friendly (translate: tough to mess up).  Not interested in multiple amps in order to save a couple of pennies.  Am interested in saving $1,000 on the audio system if it sounds good/great.  The Ascends are slightly cheaper than any of the Omegas.  Now if I can squeeze a small system into the master bedroom, it'd be the Omegas.

[mcgsxr]

That is a very well thought out set of statements, and I think you have done an admirable job of putting forth what you want.

I cannot say if the any of my suggestions are a fit for you, you'd have to hear them and then tell me!

In any case, I love your speakers, wish I could hear them, and wish you all the best in your hunt - if you can, do audition some form of digital amp (at whatever pricepoint) just for kicks, you never know....

Mark in Canada

[mcgsxr]

JLM I sent you a PM.

Mark in Canada