balancing speakers

[JohnST]

I have an amplifier, audiolab 8000a, which powers two pair of speakers. One pair are KEF series 104, circa 1974, and the other pair are celestion ditton circa 1966.

The speakers, which are in different rooms, have very different power requirements - I believe the KEFs are 80 watt and the dittons are 25 watt.

I want to place something in between the amp and the Dittons to equalise the output.

All suggestions are welcome with the caveat that I am fairly ignorant about things electonic.

regards,

JOhn

 

[Rocky]

IMO you should get another amplifier (so you can use two), for instance build a gainclone, or replace one of the speaker sets with a better match in sensitivity. Ofcourse, you can L-pad (passive XO component) the highest sensitivity speaker pair to match the lowest sensitivity pair, but you'll loose some detail on the celestions. Try it, it's cheap as it'll only cost you 4 resistors on the celestion speakers. You will need to figure out sensitivity (dB/W/m) and impedance to calculate resistor values. Check out L-pad in a crossover FAQ.

 

[Paradise_Ice]

The audiolab does not like a big load on it so be careful, i used to repair audiolab amplifiers and the main reason for there death was over loading them with to many speakers.

If you want to reduce the output then just get a pair of 2.2 ohm resistor and put them in series with your celestion or maybe a 1.0 ohm resistor just make sure its a high power resistor maybe 20 watts or 2 small 10 watts in parallel so they dont get to hot.

 

[JohnST]

Rocky and Paradise Ice, many thanks for your replies.

In the light of Paradise Ice's reply I can see why you suggest another amp but the audiolab has managed to drive this, albeit unsatisfactory, arrangement for a number of years.

I will try the resistor route for the moment - the KEFs are 8 ohm and the Dittons are 4 ohm.

Paradise Ice - am I right in thinking that each ditton speaker will need a pair of 2.2 ohm resistors - sorry if it appear to be obvious but it is so long ago that I did any physics that I am reaonable ignorant.

Thanks again

regards,
John