View Full Version : 8 Ohm 5K crossover and supertweeter in parallel to 16 Ohm mid horn leg

02-12-2014, 03:29 PM
I have been happily using two JBL theater speakers from the 1960s. The old cabinets with two 32 Ohm 15" drivers in a big bass horn and the earlier 3160 crossover driving the 375 driver and midrange horn and lens, powered by a McIntosh MC2120. The horn is 16 Ohm and rolls off over 9K. I recently added an Eminence 8 Ohm crossover (at 5K) and an Eminence supertweeter in parallel with the mid horn circuit to get the top octave. The fellow at Eminence said that there would not be any problem as the 5K crossover point would not degrade the mid horn's performance or impedance, or affect the JBL crossover. I added 8 Ohm L-pads to quiet the supertweeters a bit and things sound good. Does anyone see an audible or electrical problem with this setup?

Also, is there a test or practical way to decide if a horn driver should be wired the same polarity as the woofer, or opposite polarity? I have a 3115A network. I am curious about phase relationships. Perhaps the images will help.

pix -

Theater speaker with supertweeter on top of mid horn, next to Lava Lamp.
The head is a Theremin.:bouncy:

Two ways to wire drivers to 3115A for another system.:confused:

02-15-2014, 01:49 PM
5k would be ok since a standard 375 rolls off around there anyways. Unless you've got 2441 diaphragms in them 9k is unobtainable.

you want to wire the tweeter crossover on the input of your 3160.

I don't know if anyone told you this but the eminence apt tweeter aren't really a super tweeter. In fact there response crashes like a lead brick in water at around 10khz. As for the phase. If the horn has a 2nd order bandpass crossover on it its normal to invert the phase.

are those c550 back horns? I diyed a pair. I love them. Are you lucky enough to have 150-4c woofers in them? If you do I'm jealous, lol.

I basically have the same setup as you except I'm running 416-8b woofers and 2445 2" drivers. Plus a altec 802-8d for tweeters. I use an active crossover between the woofers and mids. I use a first order crossover between the mids and tweeters.

A very cool systems non the less.