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Exciting new line of fullrange drivers from Feastrex

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Nelson Pass said:


The whole point of the F3 was to emulate a triode with a power JFET
operating in the "linear" triode-like region. A fine SET would be the
go-to choice, and by "fine" I mean something with .1% thd or less
at 1 watt.

:cool:


Is there a specific reason for such a low THD requirement at 1-watt? For smaller DHTs like a 45 or 2A3, getting that low a figure (without feedback) could be a challenge.

Regards, KM
 
Structual View of MCAP-CR

Richidoo said:
Nice to see the latest interesting Feastrex updates from everyone. Shegeri, I am intesterested in your b version box for D5nf, is it actually possible to build it without going crazy? I do not like puzzles ;) I enjoyed reading the papers.

bven, Those who have heard the combination have said that the F5 is delicious on the Feastrex drivers. It is not difficult to build with a PCB, checkout the group buy in Pass forum. Also new ones are on sale now at renohifi.com 2200usd

I am working slowly on a simple spherical sealed box for D5nf.

The OB looks awesome Phil!


Hello Richidoo,

MCAP-CR enclosure is more complex than double bass reflex, but not much. Some skill is required, but not so difficult, if cutting dimensions are accurate enough (may be +/- 0.1mm to 0.2mm).
I uploaded internal structural photographs in my page.
I appreciate it if you try this.

Shigeruhttp://www.geocities.com/sg_suzuki/documents/TR130_assembly_photographs_with_internal_views.pdf
 
MDOFCR for Feastrex 9e

Shigeru-san,

In one ou your previous posts, you mentioned that Feastrex is evalutaing your designs? Any outcome yet? Does Teramoto-san like it? DO you have a design for the Feastrex D9e? I would like to build one to try on my D9e. Also, what type of wood do you recommend for your boxes? Birch or Marine plywood?
 
The one and only
Joined 2001
Paid Member
kmaier said:
Is there a specific reason for such a low THD requirement at 1-watt? For smaller DHTs like a 45 or 2A3, getting that low a figure (without feedback) could be a challenge.

Yes, it is a challenge, in fact there are SETs out there that measure
1% at 1 watt with negative feedback.

I set the bar at .1%. Having spent time with several SET examples,
amplifiers with 1% 2nd harmonic at 1 watt are problematic unless you
only want to listen to very simple music.

With anything more than just a single vocal or instrument, then
inter-modulation distortion is simply too audible, and the performance
wearisome.

:cool:
 
Re: OB and the Feastrex... A short story of love and hate

Phil Townsend said:
In a nutshell it is everything I want and need in a driver/box combo...or boxless combo as is the case here.
If you boys and girls out there in cyberspace have not tried the OB and the Feastrex all I can say is shame, shame on you. Get your sorry ***** in gear and build yourself an OB. You will be amazed and delighted.
A few pages ago I showed some pix....
The size is not so critical. But big is good. Mine was 18 inches wide and 40 inches ish high.
I plan to build another. I'll go 24 wide and 45 or so high. I might try a 15 inch Tone Tubby.

I love the sound, the tone, the very wide and deep soundstage, no stuffing, no muss, no fuss.
What I dont love... The price of the Featrex 9Dnf.
Oh well...
I have built this one for my client/friend, Johanna, so the question remains,
Will I pony up the bucks for a pair of 9Dnf's for myself?

If you know some (much cheaper) alternatives in the 8-10" range, let me know.
Unfortunately I cannot pony up the bucks for the Feastrex :/
 
Re: MDOFCR for Feastrex 9e

ddriveman said:
Shigeru-san,

In one ou your previous posts, you mentioned that Feastrex is evalutaing your designs? Any outcome yet? Does Teramoto-san like it? DO you have a design for the Feastrex D9e? I would like to build one to try on my D9e. Also, what type of wood do you recommend for your boxes? Birch or Marine plywood?


Hello ddriveman,

Mr. Teramoto called me to pick up these cabinets (TR130d) on March 15, but I was not at home then. He became really busy since then and it did not happen yet. He is really interested in MCAP-CR. I will write an email to him.
You may write an email to him.
I will write report on my website later.

Shigeru
 
Nelson Pass said:


Yes, it is a challenge, in fact there are SETs out there that measure
1% at 1 watt with negative feedback.

I set the bar at .1%. Having spent time with several SET examples,
amplifiers with 1% 2nd harmonic at 1 watt are problematic unless you
only want to listen to very simple music.

With anything more than just a single vocal or instrument, then
inter-modulation distortion is simply too audible, and the performance
wearisome.

:cool:


Agreed, it's a challenge. IMHO, negative feedback diminishes many of benefits of using a pure SET design. With careful design, parts selection, chassis layout and hand-selected/matched-tubes, I've managed to get down to 0.35% @ 1-watt (45 DHT with zero feedback). I'm not certain it can be reduced much more, at least not by much.

If your (THD) requirement is accurate versus perceived performance, than most, if not all, SET amps are incapable of proper playback with more complex material. I'm not disagreeing with your assessment of the perceived performance, but I'm not completely certain that 0.1% is the make or break target.

Regards, KM
 
MDOFCR for D9e

Shigeru-san,

Thanks for your reply. I will be in Japan on May 1 and hope to see Teramoto in Nirasaki. Maybe your TR103d will be there. Hope to listen to it. Also, BTW has contacted you about building a D9e version and I am the same person mentioned by him. Hope to build your design here in Singapore. We have high hopes that your design will be better than current Feastrex box.
 
ddriveman,

Please be sure to let me know if you have any free time while you are in Japan next time -- depending on your schedule, I may be able to invite you to a concert. And I hope I can join you in Nirasaki. The folks at Feastrex have been "up to no good" again on several fronts, so it should be a lot of fun to visit there.

-- Chris
 
Re: MDOFCR for D9e

ddriveman said:
Shigeru-san,

Thanks for your reply. I will be in Japan on May 1 and hope to see Teramoto in Nirasaki. Maybe your TR103d will be there. Hope to listen to it. Also, BTW has contacted you about building a D9e version and I am the same person mentioned by him. Hope to build your design here in Singapore. We have high hopes that your design will be better than current Feastrex box.


Hello ddriveman,

You will visit Feastrex on May first. How about planning to visit me before or after? I live in very convenient place in Tokyo: just fifteen minutes walk from Akihabara. You can hear my Feastrex system TR130c in my page.
Please email me.

Best regards,

Shigeru
 
The one and only
Joined 2001
Paid Member
kmaier said:
Agreed, it's a challenge. IMHO, negative feedback diminishes many of benefits of using a pure SET design. With careful design, parts selection, chassis layout and hand-selected/matched-tubes, I've managed to get down to 0.35% @ 1-watt (45 DHT with zero feedback). I'm not certain it can be reduced much more, at least not by much.

If your (THD) requirement is accurate versus perceived performance, than most, if not all, SET amps are incapable of proper playback with more complex material. I'm not disagreeing with your assessment of the perceived performance, but I'm not completely certain that 0.1% is the make or break target.

Of course I did not make a distinction in my comment with regard
to feedback.

Certainly no-feedback has its charms, however a balance must be
struck. Most people would agree that at some arbitrarily high
distortion figure, the potential benefit of no-feedback is less
important. If this is the case, then we are only talking about
where this point might occur.

I find 1% sufficiently problematic that I have arbitrarily set the
bar at .1%. I imply no reproach if you reach a different number.

I can achieve better than the .1% @ 1w @ 1 KHz easily with solid
state; how could it be that tubes cannot do this?

:cool:
 
I can speak personally on experience with the 60L and several of the variations on the enclosures.

I have spent alot of time with the Feastrex single port enclosures and derivations (most of the derivations were of my own).

Starting with the most basic iteration, I personally prefer the sound of the single port 60L cabinets for their midrange beauty. "We live in the midrange." A simple box out of a very nice wood has so many vitrues in this arena.

Some have had to deal with what can be its strong lower midrange character, but if the box is done properly, placed properly, and finished properly, I feel that this character ceases to become an issue and is correct with regards to the reproduction of music in a typical home's acoustic enviroment. (IMO)

The beauty of the enclosure is the ease of its setup. It is meant to sound good and will sound good quite easily.

Getting to the "next level" from there for me tends to mean looking at what you already got with a fresh perspective. So I chose the Feastrex 60L enclosure as the basis for my own commercial design, which is somewhat larger than 60L. The outside looks similar but there are both subtle and major changes to the tuning scheme as well. There are alot of different sound aesthetics that can be wrought from the single port box concept, or any box concept for that matter. It is all a matter of choice. Of course, build quality and subtle design considerations play a HUGE role in the final sound and absolute performance of any speaker, especially a Feastrex. (ESPECIALLY a Feastrex...) So frequently on can find that a well built iteration "X" will sound like a completely different speaker concept altogether form a not so well built "X." I credit this disparity to the inherently powerful acoustic output of the drivers placing greater than typical demands on the acoustic behaviour of a speaker enclosure.

I should note that back in February there appeared a beautiful build of the 60L enclosure by the Feastrex team in Japan. It was outfitted with their new model of Naturflux field coil driver and the cabinets looked a little different.... not sure if they were significantly different or not, but Ill let Feastrex tell the story... The cabinet and sweet looking new driver are viewable on the Feastrex Japanese blog "beecon".

Aesthetically, I like the single port enclosure concept for the simple reason of balance. If it has vitrues, then it is in the body and carrying power in the midrange in an authentic way all the way down to the lower midrange area. This is the kind of "they are here" presence.

If you want better and better, (and simply different) then there are many and many more talented designers out there who are discovering these drivers every day it seems. So many people want to share their findings and I for one am always very excited to hear about everyone's progress.

In either case, everyone seems to be in agreement that the Feastrex recommended enclosure is at the very least "a good place to start." where you go from there is all up to you.

-Clark
 
Daydreams for sometime in the not so distant future

The Feastrex driver with its natural microfibre surrounds and cryo tempered / annealed silver voice coil was mounted in a CNC milled Mikasa-esque enclosure.

The audio signal for the speaker is split and then the high frequency component delayed for the length of the horn and then summed again with the low frequency component before the amplification.

There are now only some minor fuzzyness located somewhere in the crossover area...
 
Re: Daydreams for sometime in the not so distant future

232 said:
The Feastrex driver with its natural microfibre surrounds and cryo tempered / annealed silver voice coil

That's an interesting fantasy . . . by "natural microfibre surrounds" are you suggesting the abandonment of leather? I think the chances of that happening are small indeed. Mr. Teramoto *might* be willing to try a silver voice coil. (That is, of course, only my conjecture based on my contact with him over the years.) As for the signal processing, etc. -- you're on your own technologically because the folks at Feastrex would never think to do something like that themselves, but I'm sure Mr. Teramoto would be happy to provide "moral support" for such a daring adventure.

By any chance are you going to be at the demonstration at Koizumi Musen in Akihabara on Saturday, April 25?
http://www.koizumi-musen.com/09_04_25Feastrex-sityou.html

-- Chris
 
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