Audibility of Crossover Point

jman11964 · 25th February 2011, 05:26 PM

So ... I'm thinking of the Beyma hon tweeter, and a decent Seas 8" driver.

Directivity at about 1kHz should be a reasonable match, I can use an active crossover and be quite steep and/or use a 2nd order passive on the Beyma (I figure it needs some inline cap at least for protection).

So the integration is at least theoretically possible if not trivial.

But I'm concerned - perhaps for no good reason - about a cross there rather than away from the voice area, such as I might get with a 3-way. I used to love the ATC mids in some old proacs I had once. And as a counter-example some of the reference designs for the Excel tweeter cross pretty low.

Should I just Go For It?

Was thinking CA22RNX (I think that's the right one!). Maybe the Excel not sure.

AllenB · 26th February 2011, 02:02 AM

The ear is quite sensitive at 3-4kHz. In my opinion, that is the region to avoid. 1Khz can be made to work. If you have a directivity match there, that may be the best choice.

Pano · 26th February 2011, 03:30 AM

I've used a 1KHz crossover point a few times. It can be done. But, wow, every little change you make to it - you can hear.

At least you won't be wondering if what you did had any effect.

googlyone · 26th February 2011, 04:14 AM

I agree with Pano, a crossover at 1KHz is totally do-able, but you will find that the final result will be quite sensitive to the XO:
- Slope
- Frequency
- Impedance correction for the tweeter
- Zobel correction for the woofer.

So what is new I hear you ask? Sounds like a typical list of crossover issues!

Choosing 1KHz is getting perilously close to most tweeter resonant frequencies. This mans you will have to control these very well.

I get the impression you are thinking of using a horn. Not sure which, but 1KHz is getting low for many horns - watch out for this if I understood you correctly.

Most 8 inch drivers can be pushed well beyond 1KHz, you might find there is a better compromise between toe woofer and tweeter somewhat higher. If there is not, can you consider a midrange

???

Pano · 26th February 2011, 04:23 AM

True, I don't know why you'd need to cross an 8" as low as 1Khz, unless it was meant for sub duty or something.

planet10 · 26th February 2011, 05:29 AM

Quote:

Originally Posted by Pano

True, I don't know why you'd need to cross an 8" as low as 1Khz, unless it was meant for sub duty or something.

Because you could. 1 K XO usually easier to live with than 2-4k

dave

AllenB · 26th February 2011, 06:19 AM

Quote:

Originally Posted by googlyone

thinking of using a horn.

Here's where 1kHz is a different story with dome tweeters whose impedance at resonance will hamper tweaking of the crossover, and excursion will be limited.

jman11964 · 26th February 2011, 02:04 PM

Quote:

Originally Posted by googlyone

you will find that the final result will be quite sensitive to the XO:
- Impedance correction for the tweeter
- Zobel correction for the woofer.
...
I get the impression you are thinking of using a horn. Not sure which, but 1KHz is getting low for many horns - watch out for this if I understood you correctly.

Most 8 inch drivers can be pushed well beyond 1KHz, you might find there is a better compromise between toe woofer and tweeter somewhat higher. If there is not, can you consider a midrange

???

This will be active (and DSP) so I'm not expecting to do any impedance correction, although I might have 1st or 2nd order highpass in analogue to protect the tweeter.

The horn in question is this one: http://profesional.beyma.com/ingles/pdf/TPL150H.pdf

Much above 1k, the directivity of the 8" will start to match badly won't it?

Also there's the possibiliy of using the Excel 8" and being that much further from the cone going nuts above 4k.

gfiandy · 26th February 2011, 03:02 PM

Hi,

With a 102dB sensitivity tweeter my concern would be avoiding audible hiss especially if you are going to drive it directly from a DSP and amplifier.

Unless you have an outstanding DSP and amp you may need to use passive pad just to reduce the noise floor.

This is assuming this is for a home environment.

If you are planning a high quality pro system then this is a great choice of tweeter but then the bass speaker is then not suitable as its efficiency is too low for a pro system.

Regards,
Andrew

AllenB · 26th February 2011, 09:35 PM

Do you have a directivity plot for the tweeter before you condemn your crossover point?

The sensitivity seems like a waste. It can be done if your mind is made up, but this is an opportunity to use a pro woofer.

25th February 2011, 05:26 PM	#1
jman11964 diyAudio Member Join Date: Feb 2011	Audibility of Crossover Point So ... I'm thinking of the Beyma hon tweeter, and a decent Seas 8" driver. Directivity at about 1kHz should be a reasonable match, I can use an active crossover and be quite steep and/or use a 2nd order passive on the Beyma (I figure it needs some inline cap at least for protection). So the integration is at least theoretically possible if not trivial. But I'm concerned - perhaps for no good reason - about a cross there rather than away from the voice area, such as I might get with a 3-way. I used to love the ATC mids in some old proacs I had once. And as a counter-example some of the reference designs for the Excel tweeter cross pretty low. Should I just Go For It? Was thinking CA22RNX (I think that's the right one!). Maybe the Excel not sure.

26th February 2011, 03:30 AM	#3
Pano diyAudio Moderator Join Date: Oct 2004 Location: North Carolina Blog Entries: 4	I've used a 1KHz crossover point a few times. It can be done. But, wow, every little change you make to it - you can hear. At least you won't be wondering if what you did had any effect. __________________ Take the Speaker Voltage Test!

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26th February 2011, 02:02 AM	#2
AllenB diyAudio Member Join Date: Oct 2008	The ear is quite sensitive at 3-4kHz. In my opinion, that is the region to avoid. 1Khz can be made to work. If you have a directivity match there, that may be the best choice.

26th February 2011, 04:14 AM	#4
googlyone diyAudio Member Join Date: Nov 2006 Location: Adelaide, South Australia Blog Entries: 5	I agree with Pano, a crossover at 1KHz is totally do-able, but you will find that the final result will be quite sensitive to the XO: - Slope - Frequency - Impedance correction for the tweeter - Zobel correction for the woofer. So what is new I hear you ask? Sounds like a typical list of crossover issues! Choosing 1KHz is getting perilously close to most tweeter resonant frequencies. This mans you will have to control these very well. I get the impression you are thinking of using a horn. Not sure which, but 1KHz is getting low for many horns - watch out for this if I understood you correctly. Most 8 inch drivers can be pushed well beyond 1KHz, you might find there is a better compromise between toe woofer and tweeter somewhat higher. If there is not, can you consider a midrange ???

26th February 2011, 04:23 AM	#5
Pano diyAudio Moderator Join Date: Oct 2004 Location: North Carolina Blog Entries: 4	True, I don't know why you'd need to cross an 8" as low as 1Khz, unless it was meant for sub duty or something.

26th February 2011, 03:02 PM	#9
gfiandy Audio Engineer diyAudio Member Join Date: Jul 2003 Location: Cambridge UK	Hi, With a 102dB sensitivity tweeter my concern would be avoiding audible hiss especially if you are going to drive it directly from a DSP and amplifier. Unless you have an outstanding DSP and amp you may need to use passive pad just to reduce the noise floor. This is assuming this is for a home environment. If you are planning a high quality pro system then this is a great choice of tweeter but then the bass speaker is then not suitable as its efficiency is too low for a pro system. Regards, Andrew

26th February 2011, 09:35 PM	#10
AllenB diyAudio Member Join Date: Oct 2008	Do you have a directivity plot for the tweeter before you condemn your crossover point? The sensitivity seems like a waste. It can be done if your mind is made up, but this is an opportunity to use a pro woofer.

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