Monday, April 28, 2008

Dynamics To The People - Bjørn Kolbrek's Private Website

A few posts below, I linked to the articles "Horn Theory: an Introduction" by Bjørn Kolbrek. I forgot to add a link to his private website. I have actually known about Kolbrek and his horns for years, he's had his system up online for years now. It has been fun to follow his developments and I was extremely jealous of the "Kolbrek Sub Horn". I didn't realise his engineering background, the papers published in AudioXpress took me sort of by surprise.

In any case, it is interesting to see what kind of stuff is built by someone who knows what is important and what isn't.

Friday, April 18, 2008

Hornresp 19.00

I passed announcing the release of versions 18.20 and 18.30, because I thought it was getting a little too much, announcing updates almost every other day. This is a fully new version, however, so I am glad to announce it.

I am even more glad that I had something to do with it. David McBean is open to suggestions for his software and many DIY-ers give them. I took the opportunity to ask for off-set driver mounting. This means mounting the driver not at the throat, but at some other location along the horn path. This alters response and can therefore be used to tune the horn in a specific way. Just one more tool in the toolbox. The trick itself, off-set driver mounting, is also known from transmissionlines and TQWTs.

Anyway, David refused initially, but suprised me by releasing version 19.00, with the off-set driver mounting. Thanks David!

Hornresp download site.

Chance Google Find: Horn/Dipole Hybrid

I was looking for Onkens, go figure... :)

Published on diyaudio, by CLS. The midhorn is an Oris 150 by BD-Design, in this case not used with fullrange drivers, but with a focal midrange driver. This system really struck me, because it's an interesting combination between a few things.

First of all, I am a fan of the Oris-style tractrix/fullrange approach to midrange. I have been sold since hearing various Oris systems at the BD-Design showroom and in private homes. A hornloaded fullrange driver gives an excellent overall combination of range, dynamics, resolution and easily achievable coherence. The compressiondriver loaded Oris horn takes it a step further, but the price reflects that as well. I don't have the budget for real Oris horns at the moment, but I have been able to get at least some of the magic with DIY horns, which is proof-of-concept to me. Clearly, the maker of the featured system took a different approach and uses separate midrange and treble drivers, which is fine too. In general, the directional nature of a tractrix horn reduces negative room interactions in a domestic environment (less reflections off side walls), which is useful.

Next is the dipole section. Dipoles are very hot for bass at the moment, partly because they excite roommodes less. The front and rear waves are out of phase, they meet at the edge of the baffle and cancel each other out. In a normal box speaker, the sound is radiated in all directions, but in an open baffle speaker the radiation towards the sides is much reduced. With less sound going into your room, there is less chance of room resonances and other room interactions. Dipoles are also much less efficient than basshorns or box speakers. Overall, people that use dipole bass seem to value the reduced room interaction more than efficiency. You can read more about dipoles at Linkwitz's site or, if you can read German, at dipol+. Also note that dipole is also used for midrange and treble applications and there are strong points to be made for that as well. Linkwitz is a particularly good source for that.

In any case, considering midrange horns are appreciated for their reduced room interactions, and dipole bass sections are appreciated for their reduced room interactions, it seems logical to combine the two. This full blown approach, with three 18" woofers per side, also seems to aim to "fix" the lower efficiency of the dipole section compared to the midrange and treble section. It's large (the television is 53", for reference), I wouldn't readily put it in my own living room, but I see the how and why behind the design.

Finally, it reminded me a lot of the Western Electric theater horns with dipole bass sections. Their obvious strong point was the elaborate and finely designed HUGE midrange horn. Their obvious weak point is the extreme time delay caused by the very long midrange horn. The added path of the soundwaves makes them arrive much later at the listener's ears than the soundwaves from the woofer. According to the Lansing Heritage website (also the source of the image), the delay issue was so serious, that the click sounds from tap dancing could be heard twice; once from the woofer and once from the midrange horn! The featured system is a nice iteration of the Western Electric style system. It features a midrange horn with a fairly low cutoff, mated with a dipole bass section, without the tremendous time delay.

Saturday, April 12, 2008

More wood/DIY multicell horns

I knew I had a nice link somewhere in my bookmarks...

This is a French effort, from the website, showing audio gear by Jerome and Thierry Prevost. I havn't had contact with them, but I assume they are brothers sharing a nice hobby. :)

They have several pages detailing this and other horn developments and show some of the design and construction steps. It's all in French so might be a problem for some, but the pictures alone are worth more than a million words.

(Note: although this horn consists of cells, due to its general lay-out and expansion style, it would probably be more accurately described as a radial horn. Examples of this style follow later.)

Thursday, April 10, 2008

CH Audio Design - beautiful craftmanship

I just came across the CH Audio Design website, through a link posted on Audiotreff. This company (or person?) offers spectacular wood reproductions of the Altec 1505B multicell horns. This style of hornbuilding, splitting the horn into smaller segments and pointing them in a radiating style, is intended to prevent beaming. These smaller segments are the multicells. In the usable pass-band, the wavefronts of the individual horns combine well and a smooth response and wide dispersion is achieved. At higher frequencies, each individual multicell exhibits beaming.

There is more than just pretty pictures there, including a set of drawings for an adjustable base assembly, allowing variable tilting. If, like me, you are used to adjust the position and angle of your midhorns by adding books to the stack underneath your driver (...), you will surely appreciate this feature. :) Also interesting to see is Dietmar of Germany's system. Clearly a Big Rig.

Tuesday, April 1, 2008


I am pleased to announce that this blog has had over 10,000 pageviews since it's start. It's a real joy when people read what you collect/write for them, so thanks for stopping by every now and then!

Sitemeter offers a lot more information than just pageviews. It also shows entry pages, referrals, what search words were typed in Google to get to this page and also, interestingly, how you *left* this site. I set out to make this page a place that could direct you to the information about horns you want to find, good quality stuff that you want to read. It seems that many of you do indeed follow the links and look at the stuff. I am happy to reach that goal.

Also, a lot of people look for stuff on JABO horns. I will endulge and string together some JABO stuff.

Otherwise, just thanks and I'll try to keep it up.