Horn Issues

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After reading through many posts, and surfing the web a considerable amount, I have come to the conclusion that I have formed no conclusion. Maybe some of you guys can help straighten me out. The anti-depressants help. Here's the deal: I'm a mechanical engineer by trade (power plant startup), a dabbler in guitar/mandolin building, woodworker/furniture builder at heart, mid-40's, divorced, small apartment (but my office houses a nice area where all my tools are set up), and too much time on my hands. I'm starting a 2A3 SET amp project. My son and all of his buddies (12-14 yrs old) are all involved with music (listening/playing instruments/singing/choir/etc) and they think I'm the ultimate nut because I'm always into building something. I'm probably on the 12-14 yr-old wavelength........Anyway they are always interested in what I'm doing. So I'm going to build a set of horns for my amp. It's going in my apartment. I'm looking at the Fostex FE103E's and the FE126E's. Bothe are very economical drivers as you guys know. Baltic birch 3/4" ply is easily obtainable and very economical as well. Looking at the Fostex designs and the Buschorn design, and few others, a horn based on one of the two drivers mentioned above comes out for well under $100. Now, I like the looks of the horns with the horn opening in the front, but I see a lot of designs with the opening towards the back...........hmmmmmmmmmm

What is the general concensus on front/rear openings, especially when using the above drivers or similar?

The lads are all ears and eyes on this one as several are getting into doing some building as well. I really admire their interest and want to nurture that through good example.

Comments???? Advice???



I think I understand your point. A frontfiring type of enclosure looks a lot cooler for these youngsters the same way a car has to have presence up front or let's say a woman for that matter. However, the rearfiring enclosures benefit from better bass when placed near a rear wall/corner because the hornprinciple is still working as soundwaves are bounced of the rear wall and are being directed at the listener. Of course this is a pretty simplified explanation of some complex theory but making the walls or corners work for you to produce better bass might prevale over the sexy looks of the alternatives.
if you use the drivers fullrange and want to obtain some bass from the front horn, it will be very long and cannot be folded, because you'd loose the highs and add colorations to the sound, and mask a lot of details. it only works for mid-highs, where the wavelength remains small.

A back horn can be folded like you want, as only the bass is taken from the rear of the driver. It will result in a more compact enclosure that benefits from the floor and corners bounce.
Well, I'm glad the concensus seems to be towards the "out the rear" version. I started on a pair of Buschorn MkII's today. I have all the pieces (baltic birch) cut out, and 1 cabinet 75% complete. In the MkII's, there are 2 voids, or hollow areas. Is it of any benefit to fill those with anything (sand, expandable foam....)? I've also seen where some people line various areas of the horn with a 'sound deadening?' material. How do we feel about this?

I really appreciate the responses...


Sand is the perfect material : it will damp out any vibrations of the cabinet, and because it is very heavy, will make the enclosure more steady on the floor. Moreover, filling these cavities will avoid them to behave as resonnators, which may affect the sound and add colorations.

If you put sand in them : be sure it is completely dry !! Unless you'll damage the wood.

Hope it helps :smash:
Some people like to fill the cavities with kitty litter. It's a little lighter and it's dryness is assured.
Personally, I would not use any sound damping material in the folds or path length. Consider a 1/2" thick Styrofoam disk glued to the back of the magnet, the same size as the magnet. Also, search for Planet10's FE103a mods for some more ideas. All these things can be done after the horn is built.
Too bad your not starting with the FE166e, you could have built Ron Clarke's latest design. The Austin


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Kitty litter..........I just happen to have 2 kitty's.........I wonder if they'd mind? I guess if I scoop and sift first, or do I use 'brand new'...? No really, that's a good idea. (man, I can see those cats scrambling out of those horns when I fire up a little Bach or Haydn!!!)

That 'Austin' is a different-looking conbobulation. Between me and my young crew, I'm sure we'll experiment and try several designs.

Back to the Buschorn MkII's, I'm wondering about things like tuning feet or some kind of broader base. These speakers will have to be in a room that is carpeted.

Thanks again!!

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