Measuring a Tweeter

mikee55 · 23rd April 2007, 05:55 PM

Hello, I just learnt, with the help of richie00boy, how to measure a woofer. I now want to make a small pair of bookshelves to go on my pc. I will be using an Audax 6" fibreglass driver, which I have measured and I want to use a tweeter which its T?S parameters are unknown. With a 2 way passive in mind, what do I need to measure on the tweeter, to mate it to the mid/bass unit.

Cheers Mike

ocool_15 · 23rd April 2007, 07:55 PM

The rear chamber is sealed on tweeters your likely to look at and likely t/s specs are not listed. A frequency response graph and an impedence sweep would be a good start. The lowest crossover for a tweeter is normally stated as 2*fs or sometimes 3*fs.

mikee55 · 23rd April 2007, 08:02 PM

Hi ocool_15, is it a simple matter of finding Fs? And would I use the same technique that I would of used for a woofer?
I used the technique from Readresearch (richie00boy)
And then use that in a crossover calculator?

Sorry for all the questions

Cheers Mike

ocool_15 · 23rd April 2007, 08:48 PM

Finding fs is the same for a woofer or tweeter, I just use a series resistance and measure the voltage drops. The peak voltage drop on the tweeter is then the Fs. A graph like below showing the impedence and frequency response will give you a good start.

You can use a crossover calculator but may find some experimentation is needed. With the woofer especially, make sure you are using the impedence at the crossover point or compensate for the voice coil inductance with a zobel.

Example Dayton Tweeter

mikee55 · 23rd April 2007, 09:35 PM

Hi ocool_15,

I'm confused again, can you explain this a little clearer. I have to admit because its worded different,( no offence) its harder to understand. I wire up my system like this

Quote:

With the woofer especially, make sure you are using the impedence at the crossover point or compensate for the voice coil inductance with a zobel.

Can you explain this any easier.

Cheers Mike.

richie00boy · 23rd April 2007, 09:40 PM

Use the same technique Mike. Start at 3kHz and sweep roughly to get you in the ball park, then you can sweep with finer resolution once you have honed in on a smaller area.

mikee55 · 23rd April 2007, 09:48 PM

Hi Rich, I've been worried in case you tell me off for using your picture. I'll set up tommorrow and let you know what I find.

Cheers

Mike.

richie00boy · 23rd April 2007, 09:50 PM

No worries Mike! You are more than welcome and thanks for the acknowledgement where you got it from

mikee55 · 23rd April 2007, 10:08 PM

Noobs click this way.

http://www.readresearch.co.uk/

mikee55 · 24th April 2007, 09:25 PM

Hello again, I have used my tools and found that I have

Fs=1146.9hz
Re=6.9 ohms

What else do I need to find out to implement this into my design?

Cheers Mike

23rd April 2007, 05:55 PM	#1
mikee55 diyAudio Member Join Date: Dec 2005 Location: West Howe	measuring a tweeter Hello, I just learnt, with the help of richie00boy, how to measure a woofer. I now want to make a small pair of bookshelves to go on my pc. I will be using an Audax 6" fibreglass driver, which I have measured and I want to use a tweeter which its T?S parameters are unknown. With a 2 way passive in mind, what do I need to measure on the tweeter, to mate it to the mid/bass unit. Cheers Mike __________________ If it don't work, I'll fix it in the mix! Or visit http://lsdp.proboards.com/index.cgi

23rd April 2007, 08:02 PM	#3
mikee55 diyAudio Member Join Date: Dec 2005 Location: West Howe	To find Fs Hi ocool_15, is it a simple matter of finding Fs? And would I use the same technique that I would of used for a woofer? I used the technique from Readresearch (richie00boy) And then use that in a crossover calculator? Sorry for all the questions Cheers Mike __________________ If it don't work, I'll fix it in the mix! Or visit http://lsdp.proboards.com/index.cgi

23rd April 2007, 09:40 PM	#6
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Use the same technique Mike. Start at 3kHz and sweep roughly to get you in the ball park, then you can sweep with finer resolution once you have honed in on a smaller area. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

23rd April 2007, 09:48 PM	#7
mikee55 diyAudio Member Join Date: Dec 2005 Location: West Howe	bitin my nails Hi Rich, I've been worried in case you tell me off for using your picture. I'll set up tommorrow and let you know what I find. Cheers Mike. __________________ If it don't work, I'll fix it in the mix! Or visit http://lsdp.proboards.com/index.cgi

23rd April 2007, 09:50 PM	#8
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	No worries Mike! You are more than welcome and thanks for the acknowledgement where you got it from __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more


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23rd April 2007, 07:55 PM	#2
ocool_15 diyAudio Member Join Date: Nov 2004 Location: sk	The rear chamber is sealed on tweeters your likely to look at and likely t/s specs are not listed. A frequency response graph and an impedence sweep would be a good start. The lowest crossover for a tweeter is normally stated as 2fs or sometimes 3fs.

23rd April 2007, 08:48 PM	#4
ocool_15 diyAudio Member Join Date: Nov 2004 Location: sk	Finding fs is the same for a woofer or tweeter, I just use a series resistance and measure the voltage drops. The peak voltage drop on the tweeter is then the Fs. A graph like below showing the impedence and frequency response will give you a good start. You can use a crossover calculator but may find some experimentation is needed. With the woofer especially, make sure you are using the impedence at the crossover point or compensate for the voice coil inductance with a zobel. Example Dayton Tweeter

23rd April 2007, 10:08 PM	#9
mikee55 diyAudio Member Join Date: Dec 2005 Location: West Howe	You're Welcome Noobs click this way. http://www.readresearch.co.uk/ __________________ If it don't work, I'll fix it in the mix! Or visit http://lsdp.proboards.com/index.cgi

24th April 2007, 09:25 PM	#10
mikee55 diyAudio Member Join Date: Dec 2005 Location: West Howe	Measuring a Tweeter Hello again, I have used my tools and found that I have Fs=1146.9hz Re=6.9 ohms What else do I need to find out to implement this into my design? Cheers Mike __________________ If it don't work, I'll fix it in the mix! Or visit http://lsdp.proboards.com/index.cgi

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