FE138ES-R - Dave, your dream came true...

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#141
Sorry for the extreme newbie followup, but regarding the notion that one does not need T/S parameters to design a horn -- only to optimize it:

For any given BLH, is it correct to say that one could put a very wide variety of drivers in it, and though it wouldn't be optimized, the drivers would still "work" to a greater or lesser extent, within the limits of the horn enclosure's tuning frequency? In other words, one could build the Hedlund Horn and slap almost any 8" driver in it (as one builder on Ebay recently claimed)? (That builder provided a way to vary the CC.)

Compared to designing BR enclosures, in which the enclosure seems to be tied almost uniquely to the driver, it seems very odd (yet appealing) to have a BLH in which a wide range of drivers may "work" (though not optimally). Is this really the case? Or am I reading this too literally? (Thanks in advance...)
 
#142
Kind of. Actually, one of the ironies about this is that BLHs are basically bass reflex boxes with extremely large vents which provide LF gain through a combination of 1/4 wave & horn actions.

Anyway, horn math in & of itself existed for decades before the T/S measure came along, so you don't automatically need them to design one, and within reason, there is a degree of flexibility over the driver. It's not a good idea to make major changes of course, but units with roughly similar characteristics will usually work acceptably.
 
#144
M. Paul said:
I build a TQWT with Mr. King's worksheets for the FX120 (my first self designed speaker) and have had some mail contact with Fostex for the Le of the driver (is not on their data sheet). Because they were very helpful in the past and I'm interested in the FE138ES-R too I mailed to Fostex:

"I searched the net for the TSP, but unfortunately there are not very much informations about this driver. I found the following values: fs=60Hz, Mms=5g, Qts=0.27, a=5.12cm (=>Sd=82.4cm²). Are this values o.k.? Can you help me with the missing data Vas/Bl, Re, Le, Cms?"

Here is the answer:

"Dear Mr. Paul,
The FE138ES-R is the unit which was sold in Japanese market limitedly and offered no service for the international market.
It may be hard for you to understand but almost of all Japanese customers don't use the thiel-small parameters for the box design. Thiel-small parameter is not so popular in Japan comparing with U.S.A. and Europe.
Therefore we didn't measure such data, and we are very sorry that we can't supply data what you expect.
fs/Mms/Qts/a values are correct as you said."

So there seems to be no other way as to measure the TSP to get the missing data.
But I' wondering how they calculate their enclosures in Japan?

Martin
Click to expand...

Hi Martin,

Thanks for your inquiry, and the answer from Fostex was exactly as i expected,
that´s why i didn´t bother to mail them myself.

------

and here´s the good news for all:
yesterday i finally received my woofer-tester, so i´m happily able to measure the
TSP´s this weekend !!! 😀 😀

very cheerful, Mirko
 
#145
Preliminary TSP measurement results

Hi Folks,

well, i started measuring with my WT2 and i´m utterly confused... 😕 😕
it seems that Fs and Qt are much higher than Fostex claimed and that Vas is much
lower than we expected.
i tested both drivers, here´s the first set of datas, i testet the Vas with the delta-mass-
method, the measures i took with the box-method showed no reasonable date,
because the box i used seems to be too big. i will re-measure with a smaller box tomorrow.

and i really don´t know if my results are correct...

here´s the data for both drivers:

;------------------------------------------------;
; FE138eS-R (L) Delta Mass ;
;------------------------------------------------;
; Re = 6.4628 ohms ___________ Fs = 70.739 Hz ;
; Zmax = 152.1111 ohms ______ Sd = 0.008235 m^2 ;
; Qes = 0.4094 ________________ Vas = 9.359 L ;
; Qms = 9.2259 _______________ BL = 6.047 N/A ;
; Qts = 0.3920 _______________ Mms = 5.211 g ;
; Eff = 0.0076 _____________ Cms = 971.371 uM/N ;
; Eff = 90.8284dB @1W _______ Kms = 1029.473 N/M ;
; Sens = 91.7551dB @2.83V ____ Rms = 0.251 ohms ;
; Le = 0.0351 mH @1 kHz ;
; Krm = 0.0086 Erm = 0.5702 ;
; Kxm = 0.1634 Exm = 0.2366 ;
;------------------------------------------------;

;------------------------------------------------;
; FE138eS-R (R) Delta Mass ;
;------------------------------------------------;
; Re = 6.8656 ohms __________ Fs = 65.985 Hz ;
; Zmax = 174.3551 ohms ______ Sd = 0.008235 m^2 ;
; Qes = 0.3672 ________________ Vas = 9.730 L ;
; Qms = 8.9590 _______________ BL = 6.682 N/A ;
; Qts = 0.3528 _______________ Mms = 5.760 g ;
; Eff = 0.0072 _____________ Cms = 1009.875 uM/N ;
; Eff = 90.5625dB @1W _______ Kms = 990.222 N/M ;
; Sens = 91.2267dB @2.83V ____ Rms = 0.267 ohms ;
; Le = 0.0436 mH @1 kHz ;
; Krm = 0.0118 Erm = 0.5416 ;
; Kxm = 0.1510 Exm = 0.2540 ;
;------------------------------------------------;





cheerio, Mirko
 
#146
They probably are correct. Personally, I find them believable. Fostex specs, for their smaller drivers anyway, generally appear to owe more to fantasy than they do to reality. Depends on what sort of voltage you're putting into them as well, but I doubt you're doing anything wrong.

For example, the attached is what Troel found for his FE126Es. YMMV.
 

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#147
The "Official" Fe138eS-R T/S-Parameters

Ok, this morning i measured my drivers with a smaller, now 11L , Box,
and now i´m pretty happy with the results, cause the data i got are fairly close
to the data i got from the delta-mass-tests.
so they seem to be quite consistant.

so here are the average values of the TSP´s of the 4 data-sets:

Re = 6,525 Ω
Zmax = 158,25 Ω
Le = 0,0414 mH @ 1 kHz
Fs = 67,807 Hz
Qes = 0,3851
Qms = 8,7658
Qts = 0,3689
Vas = 9,336 L
Mms = 5,717 g
Sd = 8235 mm²
BL = 6,483 N/A
SPL = 91,329 dB @ 2,83V


...more later...
cheerio, Mirko
 
#150
ianc13 said:
Mirko,

I would just like to say thanks to for gathering all this data.

I just received my pair of 138ES-R's in the post and I am sure that everyone on this thread who now owns a pair is very grateful.

Ian
Click to expand...


Dr. ODD said:
HI

My Speakers arrived Yesterday🙂 🙂 🙂

Bernhard
Click to expand...


wow, that´s great, two lucky guys recieved their babies the same days !!:cheers:

Ian and Bernhard, did you heard them yet ? and what enclosures are you two
planning to build ?


cheerio, Mirko
 
#154
HI

I have a lack of time at the moment so it will take a while till I can build my enclosures:bawling: :bawling: :bawling:
At the moment my favorit is littel enclosure + active Bass
But on the other Hand there is enough time to cange my mind about it a few times😀 😀 😀

Bernhard
 
#155
ianc13 said:
Hi Mirko,

No chance to listen to any yet. Looking forward to building some cabinets for them.

As to which cabinets:

Most likely the same as a few people on this thread 😉
Click to expand...


Hi Ian,

well, i ment if had put them any sort of test boxes for first impressions,the thing is
those drivers need alot of brak-in time, and would be a good thing, to have them
playing whie you wait for the "real" enclosures to be build.

...and the BVR is a really good decision...


cheerio, Mirko
 
#156
Dr. ODD said:
HI

I have a lack of time at the moment so it will take a while till I can build my enclosures:bawling: :bawling: :bawling:
At the moment my favorit is littel enclosure + active Bass
But on the other Hand there is enough time to cange my mind about it a few times😀 😀 😀

Bernhard
Click to expand...


Hi Bernhard,

yeah, they should play well in closed boxes with a sub. personally i think it would be a
waste to run them not fullrange, cause the es-r´s are capable to produce some decent
bass, and implemeting a sub properly is as much work (if not more) as building a large
BVR or BLH for them, otherwise, if you want a really "big" sound, a sub is the way to go.

i found out that i can simulate closed and vented boxes with my woofer-tester-2.
it does it better than the normal box-calc-softwares, cause it calculates the boxes
from the measured phase- and impedance-curves and not only from the
TS-Parameters. maybe i could help you out in finding the right volume for your boxes.


cheerio, Mirko
 
#158
I wouldn't get too excited Tom, given that only about 500 pairs were made AFAIK, & of those, probably half a dozen have made it out of Japan. I'm sure it's a great unit, but 'exclusive' is something of an understatement, and as such, there's only ever likely to be about 2 people who would benefit from a DIY offering, as the Japanese do not tend to look outside their own community for designs.
 
#160
Scottmoose said:
I wouldn't get too excited Tom, given that only about 500 pairs were made AFAIK, & of those, probably half a dozen have made it out of Japan. I'm sure it's a great unit, but 'exclusive' is something of an understatement, and as such, there's only ever likely to be about 2 people who would benefit from a DIY offering, as the Japanese do not tend to look outside their own community for designs.
Click to expand...


Hmm. Well, it might be interesting to try it but you are probably right. The 40 or so hours that go in to a design may be better spent on a more conventional offering. Shoot, when I was so sick for over a month I forgot about finishing my 168 plan. I suppose there are those that are interested in that one. That should be my priority. Regardless, I should put out a call for driver suggestions to design for. Would anyone be interested in suggestions? If so I will go ahead and start a thread for that. (Sorry guys, don't mean to hi-jack the thread)

Tom
 
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