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GrahamnDodder 16th February 2004 04:26 AM

Fostex 103 horn questions
Anyone built the 103's into Buschorn Mk ll's? Or the Fostex front design? I seem to recall Dave was gonna try the Buschorns.

I love my Solo 103's sooooo much I am going to build a horn with this wonderful little FE 103E driver. Dang, can they image. A guy can do a lot with four inches. Who knew?

Only question is, should I do the Fostex front horn design or the rear-pointing Buschorn. Aesthetics (read, "wife") would say let the mouth point back, and then I could veneer the thing like this guy did (scroll down on link) -- looks nice.

OK, so what is the word on bass (amount) and mids (coloration) on front vs rear horns. Anyone actually built (or heard) either 103 horn version? He didn't give the values on the notch filter, but it is likely ~.80mh/4.7uf/10ohm like the Solo 103's. Or would I be wrong?

Dang, this is fun.

GrahamnDodder 16th February 2004 06:39 PM

Wow. No one has built or even heard 103-based horns? :xeye:

weissi 16th February 2004 07:30 PM

Hi! Ive build that horns, but I dont have the Fostex inside....
Currently, there are some Car speakers inside.... My plan is to use it as two way, I prefer a "sparkling" sound, so Ill go for the combination Vifa TC11 & XT25, XO frequency is currently unknown....
The horn sounds very good, even with the kenwood car speakers... Parameters of the TC11 are very similar to the Fostex, so when I have them I will tell you how the bass sounds like...

GM 16th February 2004 08:44 PM

Probably have better luck here:


planet10 16th February 2004 09:13 PM

2 Attachment(s)
My buddy Chris built a set of Buschorn IIs (he took more care with corners & voids than the plans show). They have had RS40-1197s & FE103As in them (picture of FE103A before the phase plugs were added).

In any form they took, they were good. In their current form -- FE103As, rweaked with phase plugs -- they are quite stunning.


GrahamnDodder 16th February 2004 10:50 PM


What, exactly, do the phase plugs do in theory and practice?

Are those 103's, uh, rusting? Or is that Damar varnish (yet another tweak I know nothing about)...

planet10 17th February 2004 08:10 AM


Originally posted by GrahamnDodder
What, exactly, do the phase plugs do in theory and practice?
Theory... they do primarily 2 things.

1/ they approximately halve the uninterupted distance from one side of the cone to the other, pushing any cross cone resonances up at least an octave... should give a bit better highs

1a) shaped right, it can redirect HF.

2/ allows you to remove the dust cap & fill the cylinder created by the voice coil above the pole piece... this should kill the tincan resonance in that cylinder.

In practise we noted a removal of a chestiness in upper male voices, something which is a big issue in the 1197, less so in the FE103A (but still evident). Highs were also extended... The 1197 still needs a bit of help on the top, but the 103A which sometimes you wished for some extra help sometimes & sometimes not, can now get away without.


Are those 103's, uh, rusting? Or is that Damar varnish (yet another tweak I know nothing about)...
Those are FE103A. They are at least 30 years old, and commonly have a problem with the glue that holds the surrounds down to the cone migrating down on to the cone (usually requires re-glueing the surround). The other tweaks are a coat of puzzlecoat and ductseal on the baskets. Yet to happen are inside basket leg anti-reflection damping and maybe some felt to help with reflections off the spider.


GrahamnDodder 2nd March 2004 01:26 AM


I have been cruising through all of the .jp sites after searching them on google for fe103 and fe107. Geez, that little driver has quite a following over there. Tons of really neat, small 103/107/108 designs.

Given that you likely have experience with both of these designs, which would you build if you were looking to (a) preserve the intimacy and soundstage of the 103's (although Ed Schilling at the Horn Shoppe says I should drop 'em for 107's) and (b) get more moderately bass extension without using a sub.

These tqwt's:

which I like - some neat ideas on the grille mounts, etc. But I would not use screws, and I think his grille cloth is likely not very transparent, and the grille frame likely a little (sonically) constricting.


The Buschorn Mk2's that this guy built:

which we had already discussed.

Dang. I have to say I like the 103's more and more. Just looking to eeek out a tad more bass without screwing everything up if I can. But I can live without the bass if it would mean having to alter the sound of the mids that I love so much.



GrahamnDodder 2nd March 2004 02:05 AM

Actually, these are kinda nice, too, and more up your alley. Whaddya think?

Nice solution on the grilles.

planet10 2nd March 2004 02:54 AM

The 1st TQWT is of classic design -- you can toss it, the 2nd is actually an ML-TL. The Buschorn works well -- It is well worth detailing it from the existing drawings -- and would be really worthwhile reshaping the compression chamber to be shorter (but same volume).

If you only have one driver per box the BHorn is the way to go (at least till someone does an even better one). With 2 drivers a bipole can be considered.


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