Question on hi-pass tweeter x-over

[chuck55]

I am running the Tang-Band W4-616s full range and want to add this super tweeter:
add5/8 neo tweeter

I cannot get a consistent answer from the folks at Parts Express.
I would like to:
1) attenuate the tweeter by 2,3, or 4 db

and

2) hi-pass it at ~12-15,000 hz

No L-pad.
If I put the resistor after the cap., no L-pad is needed? Just the cap then resistor? What values do I use?

Is this a first-order x-over?


Tang-Band W4-616s:
http://www.partsexpress.com/pe/psho...818&FTR=264-818&CFID=1572396&CFTOKEN=81932895

 

[sreten]

Hi,

The order of the resistor / capacitor does not matter but due to
the tweeters Fs impedance peak a capacitor followed by an
L-pad arrangement, i.e. series R then parallel R is better.

Parallel R shoud be around 10R giving ~ 4 ohm nominal.
Use 4R and the series R to calculate attenuation
and 4R + series R to calculate the capacitor.

e.g. series R of 1.8R gives -3dB, ~ 6 ohm nominal, C for 13kHz = 2.0uF

This is a first order crossover.

TBH likely you need some form of BSC circuit on the
TB and then more attenuation of the supertweeter.

🙂/sreten.

 

[chuck55]

Thanks Sreton.
So I would be using 7.56 and 1.89 ohms for -3db attenuation?
I have choices of 1.5 / 2.0 / 7.5 for non-inductive resistors.
HERE:
http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=004-2
or HERE for 1.8 or 2.0:

http://www.partsexpress.com/pe/psho...016-2&FTR=016-2&CFID=1572396&CFTOKEN=81932895

What about for 2 dB and 4 dB attenuation?

Fro the cap I have 1.5uf for 14khz, 2.2uf for 13 kHz, and 2.7uf for 11kHz. Is this correct?

Thanks again.

 

[sreten]

Hi,

7.5||6 = 3.3 so tweeter impedance = 3.5 to 4 over most of the range.
Lets say 3.7R nominal. 20log (3.7/(3.7+1.8)) = -3.5 dB. Assuming 7.5R :
1.5R = - 3dB Rin = 5.2R, 2.2R = -4dB Rin = 5.6R, 1.0R = -2dB Rin = 4.7R.

for 4.7R Rin : 2.2uF = 15kHz, 3.3uF = 10kHz, scale for other Rin / F's.

🙂/sreten.