tweeter tweak/match

[paulj]

I am trying to integrate my new tweeters into my speaker setup. The old, blown original tweeters (Monitor Audio gold dome) were too expensive to recone; I am trying to get close to the same sound, which is proving tricky!

I am part of the way there - had to incorporate a fixed L-pad into the crossover (plus an extra resistor in series) to attenuate sufficiently to match the bass/mid driver's efficiency.

However, the new tweeters (now broken-in and attenuated) are still a bit harsh, especially with female vocals. I was thinking of changing the capacitor from 2.2 uF (the original setup) to 1.5, which would increase the low crossover from 9000 to 13000 (but still with a 6db rolloff). What about changing from the exisitng Bennic cap to a better one, say Solen or Auricap, with or without changing the rating? Thoughts anyone?

I am listening more critically than I did before the original tweeters blew, but that's my problem! If I can't get the right sound, I'll get new speakers!!

[rabbitz]

You might have to arm yourself with a handful of metalised polypropylene caps and a bit of trial and error. If the new tweeter has a lower impedance than the original, you'd have to increase you cap value. For example if the original was 8ohm then 2.2uF, 6ohm 2.9uF, 4ohm 4.4uF crossing over at 9000Hz. You still basically want to crossover at the same point or you'll get a dip in the xo.

The original should have some markings on it showing impedance and the new one as well. You should be able to find a impedance graph on the new one which will show you the impedance at the xo frequency and not the nominal.

Bit puzzled with the extra resistor as you should let the L-Pad do the attenuation and the extra resistor will alter the xo values as the tweeter will now have a higher impedance. That series resistor will be pushing the tweeter xo much lower.

Try attenuating with an L-Pad only and then play around with the caps.

Hang in there.

[paulj]

Thanks for your advice. I'll get rid of the extra resistor in series and try the different caps. I might also put in a coil to steepen the crossover curve to 12db/oct.