compression tweeters for <$200

[Ang]

After the (net) buzz from the Emerald Physic cs2 with the BMS 4540 tweeter going down to 1KHz, I started wondering if there were any alternatives that sound even better in a 12" waveguide for a 2-way design.

There aren't a lot of reviews of these pro drivers so if you've got experience with them please chime in.

[Magnetar]

I have used both small and large format BMS drivers and have to say they really aren't my idea of high fidelity. They sound hard, brittle and fake compared to:

If you want to go to 1K try the Beyma CP380 LINK

They sound better than the big dollar TAD's to me.

Look at the Radians too - They are 'updated Emilars' (I love my Emilar 320's = 3" aluminum diaphrgm 2" exit but good luck finding a pair)

[el`Ol]

Lynn Olson reported about the excellent performance of a speaker using the 380 in an other thread, and we all know he is no born horn-lover. If you desire to clone the Emerald also have a look at this:
http://www.seleniumloudspeakers.com/...w3-slf_new.pdf
It has a performance around 1kHz (especially off-axis) any Eminence can only dream about.

[cph2000]

This might be an "off" question - but why not try a more conventional dome tweeter with a large diameter wave guide, there must be solutions that could go as low but without the extreme senesitivity (IMHO not needed when going the dsp route anyhow) ?

[Sjef]

Ang, when I see the pictures of the backside of the Emerald Physiscs they are defenatly not using BMS drivers, don't know what they are using because a lot of compression drivers look about the same, the BMS drivers look different though.

Magnetar,
The BMS drivers right out of the box with some kind of crossover sound very terrible indeed. First I have tried them on some 18sound waveguides and it was plain terrible, some very cheap 18sound drivers I hade sounded much better on them. Same story went with some other cheap waveguides, all very nasty, while o.k. with my other drivers. After that I had some custom waveguides made by Martin Goedeke and this finally started to sound very decent. the bms do need some special attention and they sure need some mods on themselves as well. After doing so they sounded very clear, open, detailed etc. When I just got them I was very dissapointed and couldn't even believe taht someone would produce such crap in the first place. Now they sound better then my JBL's and B&C's

cph2000,
there's been a lot of discusiion before on using compression drivers vs. domes in waveguides. The first thing you have to understand is how the waveguide actually works and the look at the difference in radiation patteren at the exit of a compression driver vs a dome tweeter and there's no doubt left that a compression driver would work much better in this application. Besides, a lot of compression drivers offer much more value for money then there hifi counterparts anyway.

[tinitus]

Sjef, could you please tell us more about how to mod those BMS

[cph2000]

Remember, I was sugesting the use of a waveguide with a normal dome. I could never live with a true horn tweeter in my hifi system, but that is a matter of taste I guess - in any case the distortion figures of the beyma driver look pretty high to me, even with the horn. Zaphs distortion numbers on the dome horn conversion test looks a lot better, about 30dB for 2nd harmonic (knowing it is hard to compare two distortion meassurements when not done in the same setup)

[audiokinesis]

Lynn made some positive comments on what he heard in my room, so my system might be the one el 'Ol is referring to. Unfortunately I mis-spoke to Lynn and several others which Beyma compression driver I was using in the speakers I showed at RMAF.

The compression driver I use is the Beyma CP385/Nd, not the CP380. I also do a modification to the CP395/Nd.

Sorry 'bout giving out the wrong model number like that. I didn't reject the CP380; just never tried it. I think they use the same diaphragm and voice coil but the CP385 has a slightly more powerful neodymium magnet. Unfortunately, it is also north of the Ang's $200 ceiling.

The CP385/Nd is down 3 dB at 17.5 kHz in my application; the published curve makes it look like it barely squeaks up to 13 kHz. I suspect this driver gets overlooked by a lot of people because of that curve. I wonder if maybe they screwed up and published the wrong curve or something.

Cph2000, might I suggest that sometimes there are exceptions to the rules, and that in audio it is often those exceptions that are the most interesting. I presume you don't like the edginess that characterizes most prosound horns, but that is caused by distortions that can be addressed.

Duke

[audiokinesis]

Typo in the post above and I'm outside my 30-minute editing window: There's no such thing as a CP395/Nd. That should have been CP385/Nd.

Duke

[Sjef]

3db down at 17,5 kHz is nothing I should ever worry about. I have heard many system that don't go higher then 15kHz sounding much better then a lot of the "these go up to 100kHz" systems.

I don't have any experience with the Beyma drivers but they seem very nice. I only know the little cp21 wich is quite good as super tweeter, real ribbon like quality, despite what the measurement tells you.

The BMS diaprhagms are on an intergrated part with the phase plug. This pase plug is made of hollow plastic. when you tap your finger on the bak of the drivers there is some nasty plastic resonant sound coming out of the waveguide/horn in front. I just ripped of the bms logo and fille the hollow phase plug with two-component glue and let it harden out. After that I glued a piece small piece of plastic compound damping material on the back. Don't know the name of the material, it's an industrial machine damping material.

when I tap my nail on the back now there's is a very quiet, short, dry tick coming out of the waveguides and the detail, lushness of the driver is vastly improved. very simple but very effective. without this there's sometimes a earbleeding shout of the drivers.