Compound hornloudspeakers

[angeloitacare]

i discovered today a homepage, which shows a Compound hornloudspeaker , invented 1936 by Harry F. Olson und Frank Massa.
It seems to me this speaker configuration has been completely forgotten , but looks amazingly clever. These guys were far ahead of their time.



it would not be easy to be built, but the result might be worth the effort.

more about it at my forum

Angelo

[sdclc126]

Those look like transmission lines.

[aubergine]

Hornloaded on front, tl on back. Is that right? The driver would experience loading on both sides is my guess, better?

There's a few more designs like that, way back everybody wanted to get as much from one woofer as possible.

On a tangent
Have you heard a Tasco Harwell 215 bass unit?

[Scottmoose]

I don't think so. I imagine GM would know exactly which of Olson's designs it is, but FWIW, the picture's dodgy, but it looks to me like an early version of one of his Studio horns. There might be some QW / TL action in the bottom octave of the bass-horn's BW, but it's going to be maintaining horn loading down a long way compared to a lot. You're only seeing 1/2 of the total horn CSA there as it's using concentric radiation (mouth on the top, bottom & both sides) & unless I've missed my guess, it'll be running anything from an 8in to a 15in driver, which gives you some idea of the size of the thing.

Anyway, compound horn = one of the better compromises when a back-horn gets involved, & 7 decades on Olson's horns are still amongst the best around. Fairly rare, mainly due to their size & complexity, as well as the difficultly of matching the outputs from the front & rear. They're not unknown though -Tannoy have been using compound loading with their GRF Autographs & now Westminster Royal's since the 1960s (not that I rate them very highly).

[soongsc]

It can be a very interesting load to the driver if the back bends are used skillfully. The front side would create an interesting response with a full range driver. Hmm.

[aubergine]

I've seen examples of this in other cabs, but I just can't place them! The horn at the back I remember did not surround the HF horn, but instead went downwards to look like a classically folded BLH only with a FLH tacked on the front...anyone?

[angeloitacare]

the throat of the basshorn surrounding the HF horn is a big advantage, the transducer acts almost like a true pointsource - and hornloaded gives that " fast " and powerful bass. the backwave not in phase: i don't see any problem, since the frequency band is another one than of the MH - almost no cancellation will occure. what i do not like - is the format. In fact it would be very large - not useful for most homes. However, the cabinet could be shaped .

Stephan Stoske made a similar designstudy with his Wellenwannenhorn:

[Scottmoose]

I don't think Olson had homes in mind when he designed most of his cabinets.

[mightym]

I have been searching for info on compound horn systems for a while, mostly without much result. At least none beyond the Tannoy autograph.

Recently I found the Lowther TP1 London ( or Isis, depending on where the info comes from).

I also found another Olson patent #2224919, for a compound horn loudspeaker. I used Google patent search. The rear horn looks very similar to the work ascribed above, the influence he had on Nagoka is evident too.

I'm interested in the Lowther design because it utilizes an 8" fullrange driver, while I'm not of means to afford the Lowther driver, the specs. seem to favor replacement with a Fostex FE206, or the like, which I could actually afford in this lifetime. I would like to better understand the design and implementation of horns though, as I've little interest in a corner enclosure, I could measure the CSA of the Back horn on the TP1, and length, expansion etc, and try to design a new folding resulting in something not requiring corner loading ( which I've read the TP1 didn't require anyway).

I'm just not educated enough to make the judgement as to whether I would be wasting my time and effort to construct such a cabinet. Taking into account the rising nature of the response of the FE206, you would need horn loading to eq the bass, while having enough rear chamber to high pass the mid's to the front horn which would need to horn load the mid's with a roll off to the rising top end. I would like to not have to use a contouring filter, or have to pad down the response, as I'd like to drive these with a low watt class A amp with a pretty low damping factor.

Any comments or suggestions?

John

[winslow]

Someone on Audio Asylum built some of those maybe last year.