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Exciting new line of fullrange drivers from Feastrex

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Scottmoose said:
That's my point. A longer wavelength a) takes longer to produce & propagate (otherwise it would be a short wavelength) and b) naturally has a slow decay time. It's not easily damped in-room.

Strictly speaking, a bass wave (except when its production depends on the setting up of a resonance within the speaker enclosure, as in most boxes where tricks are used to increase output levels) does not take longer to produce or propagate, does it?

I can see that it would take longer for a standing wave to reach maximum amplitude in a given acoustic space, but I was allowing for that, as indeed, I allowed for it in the design of my listening room which is rather extreme LEDE as regards particularly bass through low mids (about 1000Hz). As a result the R60, though short, at least is pretty consistent to very low frequencies, judging by ear - I don't have the equipment to measure it. In this room there is very little hangover from the room itself. If I play something with sustained bass content and pause playback, it is surprising how quickly the bass stops - a revelation for some. In this room, sloppy bass is easily attributable to the box.

Quick, to me, definitely includes settling time.

As to buckets of power required for OB, current developments in speaker design - witness the Emerald Physics CS2 - suggest a valid alternate approach, and that is lots of fairly cheap, efficient pro driver cone area, class D power and lots of it, and some form of electronic compensation for dipole cancelation, like Behringer.
 
A transmission line by definition is not resonant. If it is, then its neither a transmission line, nor properly designed. Whatever you've heard obviously wasn't properly designed.

The compensation bit is one of the things that bothers me -no problem with it per se, but the more you boost the LF, the higher the driver excursion & power requirements get. Can be done, certainly, and valid, equally certainly, but the tradeoffs are not to my taste at this time. I heard a clone of the Emerald Physics speakers a week or so before last Christmas. I found the LF to be acceptable, but no more. Vile XO point as well -I felt for those drivers, I really did.

Either way, back OT, the 139 isn't the greatest driver ever made, but it's not bad either if it's loaded right (which isn't often the case).
 
Scottmoose said:
That's my point. A longer wavelength a) takes longer to produce & propagate (otherwise it would be a short wavelength) and b) naturally has a slow decay time. It's not easily damped in-room.

True if you only look at a system limited to the LF such as a HT sub, but as Dave noted/implied, the wider a point source's BW, the faster its rise time and the lower the driver's Qts, the quicker its settling time up to the limit of the amp's slew rate, so properly timing/phasing/amplitude matching the sub to critically damped mains driven by a 'fast'/damped enough amp is essential to having a 'fast', well damped wide BW system, ergo not technically an oxymoron.

GM
 
Scottmoose said:
A transmission line by definition is not resonant.

Hmm, a pipe organ's TLs pretty much define 'resonant'. ;) It's Bailey's definition of an acoustic TL IIRC that's non-resonant, i.e. aperiodic (without period), ergo a flat impedance in the passband, so by his definition any semi-resonant TL is some 'shade' of ~aperiodic.

GM
 
I stand corrected on my prose re the LF. Not one of my finer pieces of writing, that (take it like a man Scott... :D)

My definitions let me down again on the TL side. I forget I have an eccentric way of classifying boxes. :bawling: Similar to Bailey actually; I class resonant pipes as QW (or HW, depending) cabinets, & ~non-resonant / aperiodic designs as Transmission Lines, with anything in between as a hybrid. Problem is, nobody else does... :xeye:
 
frugal-phile™
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I use TL with 2 different things which i use when appropriate to confuse people or stress a point.

I use it as a synonynm for anything in Quarterwave space. And i use it as a pigeon hole for TLs in the classic vein, Bailey Radford, IMF, TDL ... pushed enuff towards aperiodic to have the 2nd impedance peak dissappear,

Tthere is a fringe that defines a TL as Bailey did in the title of the article, and hold this even in the face of reasoning that explains that even Bailey's line does not fully fit this definition. (i think maybe Scott ran into one of those guys and is just having FlashBacks. (ie PSD)

dave
 
:D Right. Bailey has much to answer for with that title, given that his cabinet manifestly was mildly resonant.

Still, irrespective of what Bailey et al actually did I generally like to classify boxes in my own mind, or what passes for it these days, as above: unresonant / aperiodic = TL, mildly resonent (what Bailey, Radford, IMF etc actually produced & called TLs) = hybrid line & highly resonant = QW. But it's idiosyncratic to say the least. I shall now shut up & go and drink the equivalent of the Atlantic in Cabernet to recover. ;)
 
Wow, had no idea TLs would result in such an active discussion. Anyway, I have a new pair of B139s and I intend to put them in TLs at some point. If they can match either the Quads or the D5nf units, I'll be happy... if not, they get sold and someone else can be happy.

Back to the drivers.... I've done more listening since returning from travel. They are just flat impressive. The sheer punch these deliver on transient material is very surprising. Some really well mastered vinyl will shine past digital sources, especially in the upper frequency spectrum. So, still happy... need to finish the enclosures up, take a few more pics while they're open and just enjoy them.

Regards, KM
 
High praise for Feastrex at Manchester Show

"The Aura Note with the little Feastrex drivers in ply cabinets, and the Marantz CD12/Air Tight with the Feastrex ply cabinets. Both were stunning, airy, detailed, natural, open and very breathy, sounded superb."

"The best: The Air Tight 300B with the Feastrex single driver, ply cabinet speakers. Gorgeous, open, musical and clean. One of the cheapest systems at the show, and murdered everything else by a long shot."


http://www.hifiwigwam.com/forum8/22113-4.html

My understanding is that the above Feastrex drivers are D5nf units -- some of the earliest D5nf units that were shipped commercially. Also, I am almost certain they were demonstrated in the smaller cabinets (about 30 liters internal volume) that Feastrex first introduced. The newer 50 liter cabinets are easier to use, and the fact that they sounded so good at the show is a testimony to the efforts of Feastrex's representative in the U.K., Select Audio. Mr. Teramoto tells me that the current D5nf drivers have been improved considerably; however, he also told me that the older drivers have a secret ingredient that the newer drivers currently lack: the passage of time. Feastrex drivers continue to sound better and better as they age, so even though the newest D5nf units sound better than the earliest D5nf units, the first D5nf units have by now aged to the point where they sound really wonderful. Feastrex has a pair of very old D5nf drivers that they keep for their own use because they are a "one-off" set using oddball parts that make them a bit different from all the other D5nf drivers, so they couldn't sell them as regular product. Mr. Teramoto frequently mentions how amazed he is by the constant gradual improvement of their sound over time. This is true of all Feastrex drivers, not just the D5nf. I hear it's true of Lowthers as well, except that in the case of Lowthers their edges are almost ready to fail about the time they finally sound their best. The Feastrex drivers should be good for half a century, at least.

-- Chris
 
Here's more on the Manchester show:
http://www.audio-talk.co.uk/phpBB2/viewtopic.php?t=470
They were indeed some of the earlierst D5nf units in the basic 30 liter enclosure.

'The Naim demo was just extraordinary. The £59k system managed to turn music into a combination of apparently unconnected sounds. It was the most unmusical "hi fi" I think I've ever heard. I did get two boiled sweets though.

In marked contrast the Feastrex speakers were the most musical and "natural" sounding thing we heard at the show IMHO. As we were listening I described them as the antithesis of what we had heard in the Naim room. For once the hype seems to be justified. I don't think you would need any treble augmentation but some well integrated bass extension would make them just fabulous. I can't imagine how good their field coil drivers must be. '


(Probably the 50-liter enclosure would have more bass.)

-- Chris
 
cdwitmer said:
Here's more on the Manchester show:
http://www.audio-talk.co.uk/phpBB2/viewtopic.php?t=470
They were indeed some of the earlierst D5nf units in the basic 30 liter enclosure.

'The Naim demo was just extraordinary. The £59k system managed to turn music into a combination of apparently unconnected sounds. It was the most unmusical "hi fi" I think I've ever heard. I did get two boiled sweets though.

In marked contrast the Feastrex speakers were the most musical and "natural" sounding thing we heard at the show IMHO. As we were listening I described them as the antithesis of what we had heard in the Naim room. For once the hype seems to be justified. I don't think you would need any treble augmentation but some well integrated bass extension would make them just fabulous. I can't imagine how good their field coil drivers must be. '


(Probably the 50-liter enclosure would have more bass.)

-- Chris

Hey, I said that! Blimey Chris how the hell did you find it?

Ian
 
On the link it shows a company that sells the D5nf driver for 900 euros each, inc 19.6% VAT.. Does anyone have the Canadian or US price list for these or any other of the Feastrex drivers? I was under the impression that the D5nf driver was going for 2 or 3 + thousand each ,or something crazy $$$$$$ like that. Man if these are like a thousand each or less then that could be doable to save for.. Dave:)
 
frugal-phile™
Joined 2001
Paid Member
cdwitmer said:
in the basic 30 liter enclosure.

(Probably the 50-liter enclosure would have more bass.)

The models show that with anything larger than 26 litrers net you get a low peak followed by a depression. There is also the potential to start loosing control. There is only so far you can push a driver with an Fs >100 Hz without a compromize elsewhere. Of course this is only a model, but work is underway to test it.

dave
 
frugal-phile™
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DaveCan said:
On the link it shows a company that sells the D5nf driver for 900 euros each, inc 19.6% VAT.. Does anyone have the Canadian or US price list for these or any other of the Feastrex drivers? I was under the impression that the D5nf driver was going for 2 or 3 + thousand each ,or something crazy $$$$$$ like that. Man if these are like a thousand each or less then that could be doable to save for.. Dave:)

Dave,

Retail is $4k /pr. There were some pairs put up at an introductory price to seed the units into the field. Those should be almpst gone by now (none left in North America anyway)

900 euros each less VAT ends up right at the early adopter price that many here took adbvanatge of.

dave
 
Since most of the "Feastrex buzz" on the Internet comes from outside Japan, I thought I'd share one Japanese blogger's thoughts:

http://shinshu.fm/MHz/44.04/archives/0000225555.html

"Since my interest in the Feastrex Naturflux series speakers had been piqued by a magazine advertisement, I visited IBI's listening room in Nirasaki. The clock on the wall of the office was set to Western European time, reflecting their overseas business focus. The listening room had a wonderful collection of vintage electronics, including an EMT 950 record player and a parallel push-pull amplifier using WE311B tubes. I listened to both the smaller 5-inch size and the larger 9-inch size drivers, with a variety of magnetic circuits, including the spherical yoke Naturflux series, the "monster magnet" alnico series, and field coil drivers -- a total of six different kinds of drivers. (There are other variations as well, depending on the materials used in the yoke, pole piece, etc. -- some drivers use high purity iron or Permendur in the magnetic circuit to enhance magnetic permeability.)

"The sound of all the drivers was characterized by a surprising sense of presence, speed, tightness, and power. Not only were bass and percussion instruments reproduced with great authority, I never heard such a lush, rich harpsichord from a 5-inch speaker before. It was an amazing experience. The pièce de résistance was the 9-inch field coil speaker. With the larger diameter there is more effortless reproduction of the bass, and the powerful motor the sound reproduction is extremely tight and precise. The high sensitivity lets the drivers reach deep into the silent portions of recordings. Their performance knocked me out. Listening to these speakers impressed upon me how a good fullrange driver has the potential to be the best speaker of all.

"If you want good sound, you have to be ready to pay the price . . . to an unemployed person such as myself, budgeting for a pair of these drivers is no easy task. I left the listening room without a pair of those speakers, feeling frustrated in the extreme. But IBI's president Mr. Akiyama gently assured me as I was leaving, 'We're trying to find ways to bring the cost down, so let's stay in touch.' I hope to find some way to be able to afford a pair, and I was grateful for Mr. Akiyama's taking time to share the speakers with me."
 
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