Very, Very cheap compression-drivers and waveguides?

I can get some very, very cheap compression-drivers that on paper looks impressive for the price.

Around 10-15Eu for a 1,5" diaphragm 30-100W rating. Build quality and size looks much better than a similar prized "hifi-tweeter".

I'm looking to match the driver with a "pro" 6" (91dB, 200/400w, above 150Hz), so I don't need 100dB/W sensitivity that a compression´-driver can do with a proper horn. Crossover around 2-2,5Khz, 4th order active filter. Not looking for audio-nirvana, but good-sounding, loud party-music ( assisted by a 12" sub).

Question 1: can a compression-driver be used with a short waveguide instead of a "real" horn or would it be hopeless?.

Question 2: how critical is the mating of horn and compression-driver? - I'm thinking about buying a few cheap one for testing, but if you say its hopeless, I'll go another route.

Kind regards TroelsM
 

kipman725

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2007-06-10 12:41 pm
Warrington
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List Your Clones

Horn/waveguide are just different names that people use depending on whether their primary objective is loading a compression driver with a desired acoustic impedance over a wide bandwidth (horn) or directivity control (waveguide). Usually cheap waveguides are just copies of other companies designs perhaps made with lower quality plastic. In terms of matching compression drivers to horns/waveguides at a basic level (beyond matching exit diameters etc) there are longer compression drivers that effectively have a portion of horn on the front of the driver (TAD ETC) and generally more modern designs that are less deep and attach to the horn at the tip of the phase plug (IE B&C DE250). A long driver won't work well with a rapidly expanding modern waveguide.
 
This one is threaded. 1,3/8" i think. 44mm Diaphragm. No usefull datasheet. 150 danish is 20Eu, but the same range of drivers goes down to 11Eu with similar build-style.

Does all threaded drivers count as "long" and require a long horn.

Kind regards TroelsM
 

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You could do something as easy as taking some 36mm thick plywood, drill a hole to allow the HF driver to mount, and use a large roundover bit in a router to make a very short horn/waveguide.

Done correctly, it'll probably provide a small boost above 10kHz, which is often where compression drivers need help.


There are lots of problems with cheap compression drivers on cheap horns, though - I measured one that had the 2-3kHz range 10dB over the rest of the range in a large bump. I'm sure you can imagine the difficulty that would present in the crossover.

Chris
 
Hi Chris

Yes, I thought about making a short horn/waveguide. I could get access to a lathe ( or build on... - I need another project like...). I'm doing active filters and I have room to do a little EQ as well.

If you search AliExpress for "Finlemho" a couple of very cheap horns pop up. I'm tempted to buy e few for testing.

(as always: a project starts out as a cheapo, and evolves into something thats, well, not so cheap...)

Kin regards TroelsM;
 
question: Would i prefer a larger or smaller diaphragm for the MRH-80 horn if the goal is to play from 2.2Khz in a 200W system with a 6" midbass?

I guess that power-handeling goes up with a larger voicecoil, and maybe also output, but whats the drawbacks? : breakup? limited HF response?

Kind regards TroelsM
 
My experience is that the mating of horn to driver is critical.
The holes must align perfectly and be the same size. You can't try 1.4" driver in a 1.5" horn throat.

Already pointed out that short fast opening guides and horns won't suit all drivers.

Le Clèac'h profile is in a class of it's own, at least on higher frequencies.
(Taken me too long to find this out, but I'm there now[emoji846])
Unfortunately that profile gives rise too huge horn diameter sizes further down the frequency range.
Unless you have a banquet hall size listening room, they are just too big

I've found that well regarded and expensive drivers do sound better than cheapies but it all depends on budget and expectations.

Good implementation will get the best out of them.

It's fun making horns. I've stuck to making conical (early system), tractrix and exponential (bass) and recently Le Clèac'h upper mid horns.
I've also turned a few pairs of Le Clèac'h tweeter horns. Depending on frequency, they can be pretty small.

Where size allows turning on my lathe and lash up horn lathe has been fun.

Go for it!
 
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