Can you increase the efficiency of vintage speakers?

Hello to all...

I have a pair of JBL L25 Prima speakers which have an efficiency of 73 - and I am wondering if I could increase the efficiency of them by rewiring them: I am now powering them with a Parasound HCA-750a ( high current 75w/c/8ohms) power amp, using the pots on the back of the amp...

I'm assuming that rewiring them would change their sound abit as well: has anyone ever experimented with this approach? 

Thought at first 73 had to be a typo. I had a pair of these myself, yellow with orange grills, and they are more like 92-95dB. 73dB is just off the charts low. But then I did a search and found the factory owner’s manual.

That must be where you got this from. The factory measures 76dB, but notice this is at FIFTEEN FEET! Modern sensitivity measurements are taken at 1m. Rest assured your L25 is a highly efficient speaker.

Anyway no, you cannot increase sensitivity by re-wiring. Oh sure someone will come along and prove me wrong. It’s a sport. You could win a prize. But by and large sensitivity is a function of the native efficiency of each driver and the size and shape and design of the loudspeaker cabinet. You could increase the sensitivity of the JBL L25 only by putting the drivers in a different cabinet.

Which I have done! My first speaker project was a transmission line design by Roger Sanders in which to save money (starving college student) I used the L25 woofers. This wasn’t really much of an increase in sensitivity, but it was a huge increase in terms of bass that was smoother, flatter, and deeper. The native sensitivity of the tweeter is something like 95dB, which is why they have the control to let you turn it down.

Which is what I would do if I were you. Messing with these like I did, transmission line, is a huge amount of work. The high density MDF alone will today probably cost more than you paid for the Primas.

The amp you have now is perfect. The Kenwood mine ran with for decades was 60 watts. So relax. You are fine. Enjoy!
You can sometimes improve the efficiency of a multi way speaker system but only if you use multi amplifiers and remove any padding.  For instance, tweeters are often padded down about 3 dB or more to match mids.  To do this they use resistors which generate heat from the lost signal.

Remove the resistors, use a line level volume control, and voila, no more wasted heat.

The other way to improve output is to use boundary reinforcement.  That is, push the speakers as close to as many walls as you can.
Thanks for your input... BTW: Miller carbon pointed out to me that the speakers are much more efficient than I was led to believe.
Presently: they are only about 12" away from the walls and sound amazing!

...enjoying these speakers immensely: presently using solid core 14g copper wire twisted together (homemade) as speaker cables - would changing this to 16g "modify"/change the sound?

"Oh sure someone will come along and prove me wrong. It’s a sport. You could win a prize."
+1 MC
middle mass

Sorry - but I am confused by your comment... Are you word-waring with millercarbon for reason?

And please explain your "+1 MC" note - it's meaning is obtuse to me within the context of this forum and my question...