On the Horns of a Dilemma

[Cloth Ears]

I've been looking for further information on this and can't really find any (and possibly my search terms are just bad...).

I found Jack Dinsdale's article on a mini-horn (his term, I think) which combines both a Front-Loaded Horn and a Back-Loaded Horn for a single driver. It was mentioned in the first and third articles he did for wireless world in 1974, which I found here and here. FYI, the second one is here.

The I had, based on these articles, would be to have an FLH (say, 12½ square inch throat) down to the baffle step (say 260Hz for a 17" wide horn mouth), run a back chamber to cut off the BLH at 260Hz (about 52 cubic inches with a 6¼ square inch throat), and then using the smaller throat for the BLH, boost the signal below 260Hz by 3-4dB. Then all you have to do is ensure that the length of the entire thing is "something-and-a-half" times the "crossover" wavelength - and 78 inches is almost exactly 1½ times 260Hz wavelength (52 inches).

Sounds simple, doesn't it? Aside from getting the horn to fit together, what's the catch? My best guess is that it doesn't work in the real world, or else it's just too complicated to actually make - although with some of the horns around, I'd say that's not the problem.

[tade]

sounds keen. Ill let it roll around in my brain!

[Cloth Ears]

The idea was to put the 'cream-cone, holey-basket Coral FE103a's I got from Bill F. to work. And I figured that this might be a way for me (a confirmed multi-driver'o'holic) might be able to try out the wonderful world of full-range.

OK. I'll probably slot in my bass bins to handle the bottom octave or 2, as they have to have a bit of SAF... ...so I can't make them too big.

[Colin]

One of the Bruce Edgar articles for Speaker Builder wasn't too complementary about the Dinsdale horns - mostly because of lack of spec for the Eagle drivers used.

[Cloth Ears]

Originally posted by Colin
One of the Bruce Edgar articles for Speaker Builder wasn't too complementary about the Dinsdale horns - mostly because of lack of spec for the Eagle drivers used.

Yup, and he didn't like the KEFs either (from the Audio Asylum posts). But I didn't see anywhere that he didn't like that actual design idea. What I'm not sure of is, that if you use different sized throats for the FLH and the BLH, do they interact badly or well?

With only the Dinsdale article available (and the promise that MJK is going to investigate this on his Quarter Wave Site) there's not much to look at. At least, I can't find it... yet.

[Cloth Ears]

Found this (at least, someone from the High Efficiency Speaker Asylum did) from Olson, which shows a FLH+BLH design. So they've been around since before 1937, yet there's not much current information on them. Also, Olson's patent seems to be (uh) incomplete (IMHO). He's got 2 new ideas, neither of which I've ever heard of in practice. The series resonant circuit in the FLH mouth sounds like something he designed while drinking (a lot of) beer from bottles, and the second constriction in the BLH doesn't sound like it would work correctly to reduce higher frequencies (at least, not while allowing the base horn section to continue to function correctly).

The Tannoy Westminster Royal is of this design, so they can be made successfully - but I wasn't planning something quite so big.

[planet10]

Originally posted by Cloth Ears
Jack Dinsdale's article... which I found here and here. FYI, the second one is here.

That is the pdf i scanned & put together. Good to see someone is hosting it.

Dinsdale has lots of good stuff in it, but it isn't bug-less. Use it as a background, not a bible.

dave

[phase_accurate]

A little OT - but I like the title of your thread. It reminds me of an article by Dindsale's wife titled : "on the dilemma of a horn .....".

This one is quite funny reading BTW.

Regards

Charles

[doggy]

These corals had a beautiful midrange, my fe108ez are nice but these were like going from a ss amp to a triode amp.One thing for sure, be careful with the volume control.

I put them into a short horn of my own. Can be seen post #85-90, page 9 of the"full range speaker gallery thread"

[Cloth Ears]

Originally posted by planet10
That is the pdf i scanned & put together. Good to see someone is hosting it.

Dinsdale has lots of good stuff in it, but it isn't bug-less. Use it as a background, not a bible.

dave

Thanks, Dave.

I've only been using it as an idea, and using the info from MJK's papers to work out some of the detail. Unfortunately he hasn't yet finished his paper on combined FL+BL horns yet.

I'm keen on using the FLH and most of the BLH to test out my 'plywood-bending' skills - to allow the 'mini-beasts' into the house. SAF is much higher when there's smooth curves of glowing Tasmanian Oak (rather than square thingies).