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A Compression Driver Flat From 10 kHz - 20 kHz
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infrasound View Drop Down
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Points: 2276 		Post Options Post Options   Thanks (0) Thanks(0)   Quote infrasound Quote  Post ReplyReply Direct Link To This Post Posted: 25 July 2012 at 11:00pm
Oops, double post

Edited by infrasound - 25 July 2012 at 11:00pm
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ceharden View Drop Down
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Points: 11776 		Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 25 July 2012 at 11:49pm
You need to be looking at quite small diaphragm compression drivers surely?  Even a 1.75" diaphragm is quite large when you're trying to do the very top end of the range.
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Elliot Thompson View Drop Down
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Originally posted by Muckerbarnes1 Muckerbarnes1 wrote:

Elliot could you establish a point to this exercise. Some are as we know awful. Some are great, and a tad of EQ is even better.


When you use equalisation to compensate the high frequency inefficiency of a compression driver, it never sounds like a driver that does not require high frequency compensation.

The results are similar to requesting a bass bin to generate 40 Hz that is –10 dB @ 40 Hz. You can boost the equaliser +10 dB @ 40 Hz, however the bass bin will not sound like a bass enclosure that is 0 dB @ 40 Hz.

There are also the fluctuations of the high frequencies from a dB standpoint in the compression driver once you go beyond 10 kHz. This is precisely the reason many companies smooth out the response curve in the graph beyond 10 kHz. It is more of a marketing tactic to make the results look more appealing. The only company I’ve seen that does not use such smoothing is BMS.

So finding a compression driver with a deviation of +/-1 dB from 10 kHz to 20 kHz lowers the chances of any severe dips within the 10 kHz – 20 kHz range not shown in a smoothed out frequency curve.

I can hear up to 20 kHz, which is unfortunate for I tend to notice faulty electronic equipment (Fluorescent lights, CTR monitors, Valves and so on) offering spikes anywhere from 17 kHz – 20 kHz while idling.

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Elliot Thompson
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Elliot Thompson View Drop Down
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Points: 5176 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 26 July 2012 at 12:03am

Originally posted by ceharden ceharden wrote:

You need to be looking at quite small diaphragm compression drivers surely?  Even a 1.75" diaphragm is quite large when you're trying to do the very top end of the range.



I agree.

A lot of those Bullet tweeters house diaphragms that are 1.5 - 1.75"

A may need to explore coaxial compression drivers.

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Elliot Thompson
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B&C DE500
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Originally posted by infrasound infrasound wrote:



Beyma CP21/22

Okay, it's not a compression driver per say. But it is ±2.5dB 10kHz-20kHz.



Thanks for the suggestion.

The Chart is showing the CP 22 offering -5 dB from 10 kHz - 18 kHz.

I never fancied bullets. To my ears they just sound like an add-on to create some tsk, tsk, tsk. You can hear the separation between the horn and the bullet. It doesn’t sound seamless to my ears. Possibly the users crossed them too high why they always gave me that impression.

This is why I prefer a compression driver that can be used in the upper mid range region all the way up to high frequencies.

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Elliot Thompson
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infrasound View Drop Down
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I know exactly what you mean, but I think in your situation it is down to the engineering of the system. Problem is that they're often run in a very narrow bandwidth as you stated, and are boosted to help increase their presence.

I have heard the CP21F sound incredibly transparent in a Hifi setup, so it can be done Big smile

-

Sure this isn't flat enough for you? 102.5dB @ 10kHz  , ±2.5dB  ,  102.5dB @ 19kHz   (CP21F)





Edited by infrasound - 26 July 2012 at 1:01am
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Never really impressed by CP21s with their somewhat limited SPL.

Not into piles of drivers, to get what I want.


Edited by levyte357 - 26 July 2012 at 12:55am
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Timebomb View Drop Down
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BMS 4595 coax is very good up the very high end, also the Fane CD 145.  As has been said most need some EQ.
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Elliot Thompson View Drop Down
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Points: 5176 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 26 July 2012 at 3:15am

Originally posted by infrasound infrasound wrote:


I know exactly what you mean, but I think in your situation it is down to the engineering of the system. Problem is that they're often run in a very narrow bandwidth as you stated, and are boosted to help increase their presence.

I have heard the CP21F sound incredibly transparent in a Hifi setup, so it can be done Big smile

-



The response looks good. I have lots (30 to be exact) of retired Motorola Piezos in addition to ten BMS 4540 Nds. If I needed a Tweeter I could use the BMS or Motorola for either one can produce 30 kHz.

What I need is a compression driver that can produce high midrange (1.5 kHz) up to high frequencies (20 kHz). It’s more about having a single point of source for high frequencies per cabinet than a multitude of tweeters that are not aligned with the horn.

It looks like a coaxial may be the only alternative.


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Elliot Thompson
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Elliot Thompson View Drop Down
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Points: 5176 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 26 July 2012 at 3:21am

Originally posted by LjudLahger LjudLahger wrote:

B&C DE500


Thanks for the suggestion.

Its a pity this driver takes a nose dive beyond 18kHz.

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Elliot Thompson
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Elliot Thompson View Drop Down
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Points: 5176 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 26 July 2012 at 3:34am

Originally posted by Timebomb Timebomb wrote:

BMS 4595 coax is very good up the very high end, also the Fane CD 145.  As has been said most need some EQ.



Thanks for the suggestion.

The 4595 is -8 dB from 10 kHz - 15 kHz. Have you heard this driver?

I'll examine the FANE CD 145.

Best Regards,
Elliot Thompson
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