Fostex FE126 EN, in Madisound BK-12M kit

[Noskipallwd]

Hello, a couple questions for those who have, or have had Fostex drivers. Planing on building my first pair of full-range horn speakers. I am considering the Madisound BK-12M kit, due to price and a small listening space. I also don't feel comfortable building the cabinets from scratch at this time. The kit uses the 4.5" FE126en driver. I will be driving them with a 16 watt PP amp for now but plan on building the Steremour soon. Would these speakers be a good match with the steremour, and would they benefit from the addition of a super tweeter such as the Fostex T90A? Thanks for any advice!

Shawn P.

[Paul Joppa]

The FE126E (I assume the -EN is similar) is rated 93dB, which by itself is satisfactory for most purposes with a 2A3 amp. (For a serious assault on orchestral music, especially in a large room, I'd like to see 96dB.)

It's a pretty small driver, so it will not likely go extremely loud without distortion no matter what power you have on hand. I doubt that you would benefit from more power than a Stereomour has to offer.

Because the BK-12 is a back-loaded horn, it may be more efficient in the bass, and hence get louder than the 93dB midrange rating suggests.

Tweeters used with these type of drivers are usually super-tweeters, crossing in for the highest octave only. They will add some air, but will also muddle the point-source character. It's a crap shoot which any one person will prefer. You'll just have to try it and see.

[Noskipallwd]

Thanks for your reply Paul, yes the EN is rated at 93db. So, if I were to use a super tweeter all I would need for the xover would be a cap? If so how would I determine the value?

Thanks again,
Shawn P.

[Thoburn]

Hi,

You might be interested in the Mark III Frugel-Horn

<http://www.frugal-horn.com/>

I think I am going to build them for my secondary system and just because they look cool.

[Paul Joppa]

...So, if I were to use a super tweeter all I would need for the xover would be a cap? If so how would I determine the value?...

That's what a lot of people do, and it's simple enough that that is where I'd start if it were me. Actually, I'd use a cap feeding an L-pad so you can adjust the level and cut-in frequency independently.

Choosing the capacitance is not as simple as it seems. The cone will have close to adequate frequency extension, measured on axis; it's the job of the tweeter to fill in some more off-axis energy (some call it "air") and perhaps to give a cleaner treble, free of Doppler distortion and cone resonances. Making that balance is a matter for listening, not for calculating. You can spend endless time on the internet getting reams of conflicting advice, or you can experiment. Obviously I'd go for the latter!

For 8 ohms, 2uF is a -3dB point of 10kHz and would be a reasonable place to start. If you want a suggestion, get a pair at 1.8uF and another at 1.2uF. That gives 3uF in parallel, 1.8, 1.2, or 0.72 in series. Between these options and the level control, you should have many happy weeks of careful listening. Get inexpensive polypropylene caps, Solens or similar, and ask Grainger about breaking them in before you make any long-term judgements. Once you have narrowed it down, then it's time to look into better caps. Same goes for tweeters, IMHO.

[Noskipallwd]

Paul thanks for all your help, I think a L-pad is a great idea. Experimenting is alot of fun! Thanks for the link to the Frugal Horn, Thoburn, they do look interesting.

Shawn P.

[debk]

I have the Fostex Fe206en's in a Madisound BK-20 cabinet.  I originally used a pair of supertweeters , but as time went on I found I liked them better with out them. i used a 3uf capacitor and a L-pad.
At first I found them a little shouty and not very smooth.  I put some small pieces of foam between the whizzer cone and the main part of the speaker.  They also needed a very long break in time over 300 hours.  With time and the foam they sound much smoother to me now.

Debra

[Noskipallwd]

Debra, thanks for your reply, I've decided to buy and build the BK-12M stock and give them an extended burn-in, then I'll know if I want to try the super tweeter. I will try the foam behind the Whizzer cone though.

Cheers,
Shawn P.

[Wanderer]

I will try the foam behind the Whizzer cone though.

The FE126En used in the BK-12m does not have a whizzer cone to put foam behind.

A buddy of mine has some older Omega speakers that used the similar Fostex 127E in a reflex box.   

[debk]

Shawn

If you go with these let us know how they sound.  I was thinking of building a pair for a secondary system.

Debra

[Noskipallwd]

Hello,
Hey Wanderer, your right about the whizzer cone, did your friend like these drivers in a Bass reflex cab?
Deb I will surely give you my impressions, after I've had a chance to build them and have some quality listening sessions. I plan on ordering them this week, I work 7 on and 7 off in a Hospital lab, so I would like to time their arrival just before my time off. I was at the DIY audio forum recently and apparently the cabinets were designed by the gentleman from Planet 10 Hi-Fi who is responsible for the Frugal-Horn. Grainger gave me some good tips on breaking the drivers in, looking forward to it. Finally finished my Crack bulild, and our fellow Bottlehead HF9 built a great new cable for my HD 650s, so I have spent most of my free time listening to some great records I have not spun in awhile, anxious to hear how they sound on some great gear.

Cheers,
Shawn P.

[Wanderer]

Hey Wanderer, your right about the whizzer cone, did your friend like these drivers in a Bass reflex cab?

My friend is using them with a older hybrid Musical Fidelity amp. He likes them, but I found them like a girl I used to date in college, Hot, Thin and Harsh.

I don't think these Omegas used any baffle step compensation ("BSC") and sound too treble forward to me. I have since talked my buddy into trying an inexpensive small Sony servo "sub"woofer Amazon had on sale for next to nothing. Adding a little "thud" to the bottom end tended to warm things up and he now likes that sound better.   

Back horn loading should take care of the BSC and has the potential to sound more ballanced sans add on helper woofer.   

[Laudanum]

I know this is getting a bit old but ...  I have a pair of older Fostex speakers, and cant remember the model number.  I was to say FE207's but not sure.  They are shielded as at the time they were going next to a CRT television (10 years ago atleast now).   Anyway, I built double bass reflex cabinets for them.  I used Damar varnish on the cones if memory serves.  I also placed a fairly efficient tweeter on the back of the enclosure.  Cannot remember the cap value I used.  The tweeter is not on an L-pad and I got very lucky with it.  It really doesnt add any treble extension that you can notice but just adds the very slightest bit of "air".  Anyway, yes they take a long break in.   They are connected to one of the original version S5 amps (cheap push pull kit amp) with a tube CDP as source or sometimes swapped over to the DIY Tube 35.  I have no idea what measurements would show, might be a mess but they actually sound really good with solid bass.  Although not extended I never felt like I was missing anything with the blues and rock that I mostly listen to.   I liked them so much that I was looking into doing something with the Sigmas but found a pair of JBL LE8TH's (need a re-foam now).

Fostex drivers are great, especially for those on a budget looking for the single driver experience.  Several models always seem to have real good potential and someone always seems to come up with good enclosure designs for them.

[Paul Joppa]

Laudanum, a cautionary note on the LE8-Ts. There are I believe several after-market replacement foam suspensions, but they have ***four times!!*** the stiffness, and raise the resonance frequency by an octave (and double the QT).

Try to get a real JBL kit installed. Those kits typically are "out of production" then every few years they make a batch of them and they are available again for a year or two. They are not cheap, but nothing else works. You can sometimes get kits to re-cone them as 2115s instead; a little more efficient and less flat response.

[Laudanum]

Thanks Paul.  Im probably 1/2 hour away from Speaker Exchange in Tampa FL.  I've spoken to them a couple times about it but was more concerned about the dustcap.  I dont know if you know who they are but they are pretty well known and have been around a long time.  They can do the re-foam without replacing the dustcap.  I also inquired about surround materials wanting to avoid butyl rubber and stay with foam which also isnt a problem.  But I didnt know about needing the specific JBL foam to retain stock parameters. Makes perfect sense though as that foam was really "soft" for lack of a technical term.   Thanks so much for mentioning it.  I will have to give them a call again.  I know that they know JBL so I may just need to talk to someone there who has been around a long time but Im a bit miffed now that they wouldnt mention it.  Hopefully it may have just been who I talked to not knowing.   These arent the alnicos but they are still great speakers.  I use them as extended range with a fostex FT17H capped and through an L-pad.  Ive had them for 10 years, they are dropped into large vented enclosures.  They are my favorites.  I may be best off trying to find the JBL re-foam kit and then brining them in with it, even if I have to wait for production.

Thanks again Paul, you probably saved me some heartache.