Hi, Tweeters in AR18BX?

[Guest]

Hello everyone,

I own a pair of AR18 BX speakers (bought mid/late 80s) in which the mid/bass drivers have blown, I replaced them with some Audax AP210ZO drivers and i have been advised by some very helpful people at www.diyaudio.com that i need to know the crossover point and slope (6 dB, 12 dB or 18 dB) of the tweeters in this model of speaker so i can cross the new driver and old tweeter over correctly.

On the back of the tweeter it says AR 1210068-0C J73TNM, if thats helpful to anyone i dont know.

Do you know if this tweeter is any good and would i be better of buying some new ones insted? I can get hold of some Audax Part no: TM025F1 tweeters easily and quite cheaply, would these be better?

If anyone wants to read my posts on diyaudio.com regarding this project you can see it here http://www.diyaudio.com/forums/showthread....31&pagenumber=1

Thankyou

[Guest Nigel]

Take a look at:

http://www.partsexpress.com/resources/xover.html

Compare the wiring in your speakers to the diagram at the middle of the page. There may also be a resistor in the speakers too, which does not affect the answer to this question.

I am surprised that the woofer you choose offeres an improvement over the AR woofer.

http://www.partsexpress.com/pe/showdetl.cf...t_ID=7819&DID=7

I would not change the AR tweeter.

Nigel

[Guest]

Thanks for the reply.

The crossover in these speakers consists of a 3uF cap in series with the tweeter, there are no inductors or resisters so i wasnt quite sure what to do with the table at Parts express.

[Guest Nigel]

If you look at the chart and pictures below, with your description, you have a 6dB/octave high pass filter.

We also know that the driver is nominally 8 ohms. The table does not go all the way to 3uF, so some calculation is required.

Using MS Excel's charting and trendline features, we find that the 6dB 8ohm data matches the following equations exactly (R^2=1):

uF = 19929 * xfreq ^ -1.0002

or

xfreq = 19891 uF ^ -0.9998

In this case 3uF results in a crossover freq of 6632Hz. If we look at ± 5% in capacitor value we have 6316Hz and 6980Hz.

Nigel

[Neal K]

On 7/1/2002 at 11:25 PM, Guest said:

Hello everyone,

I own a pair of AR18 BX speakers (bought mid/late 80s) in which the mid/bass drivers have blown, I replaced them with some Audax AP210ZO drivers and i have been advised by some very helpful people at www.diyaudio.com that i need to know the crossover point and slope (6 dB, 12 dB or 18 dB) of the tweeters in this model of speaker so i can cross the new driver and old tweeter over correctly.

On the back of the tweeter it says AR 1210068-0C J73TNM, if thats helpful to anyone i dont know.

Do you know if this tweeter is any good and would i be better of buying some new ones insted? I can get hold of some Audax Part no: TM025F1 tweeters easily and quite cheaply, would these be better?

If anyone wants to read my posts on diyaudio.com regarding this project you can see it here http://www.diyaudio.com/forums/showthread....31&pagenumber=1

Thankyou

HI, I have the same speakers. The tweeter is 8 ohms. The crossover is: LF=a 0.46 iron core inductor in series. HF= a 3 ohm resistor followed by a 3 uf cap in series 0.20 iron core inductor paralell. So it is one pole on the woofer and a 2 pole on the tweeter with a 3 ohm padding resistor. I put in a Yamaha version of the Audax TW10 myilar "Balanced drive" tweeter and it works and sounds great. you can find the part at Madisound.com.