Can someone explain to me the difference between overhung and underhung voice coils ? On the Altec Lansing Forum site we were discussing the pros and cons of installing 400 watt JBL 2225's into Altec 210 VOTT cabinets and how they would compare to the 75 watt Altec 515's that originally came in them. Jim Dickenson - think he's the president of Iconic speaker corp. (and a noted expert on the big Altec theater stuff) said this:

"An A2 has a 1M/1 watt rating of about 114 db. The mutual coupling of the 2 210 bass horns is to below 50 Hz at full level! A good 515 with a paper voice coil support handles 75 Watts AES. This gives you a max continuous SPL of about 140 at a Meter, go to 150 for peaks.

The JBL unit will handle 500 watts AES, has 98 db 1 W 1M efficiency. Max Spl is about 127 at Max. 137 at peak. It would take the JBL 2000 Watts to get to the same continuous level as the A2 at 300, the speaker simply will not handle the power. Who is more digital ready??? It is just simple math, every time you double the power you get an increase of 3 dB. The more efficient speaker wins every time. The JBLs have heavy inarticulate cones with clumsy overhung voice coils. The ALTECs and now our Iconics have light moving mass with underhung voice coils. You could simply have your 515s reconed with High Temp Voice coils and double their power handling, something we will be doing soon with our new 166 model. We have already done it with our 164 which is more intended for short bass horns and venjted boxes. It would work way better than any JBL in a 210, even though we do not recommend it for that use. Even a cast frame Eminence (3" VC) will sound better in these boxes than a JBL 2227.

The fellow above has a very old set of A2s, complete with original 515s, yes the software is probably aged, everything wears out sometime, have it repaired, not thrown away for something that does not work as well. Put new 299 style diaphragms in the drivers, then they will handle as much power as the JBLs and sound better, then biamp the system and watch the customers come to the show because "it does not hurt their ears" and sounds better. I could go on and on..... JIM "


So JBL 2225's have heavy inarticulate cones with clumsy overhung voice coils? It just seems like 400 watts into 8 JBL 2225's will blow away 75 watts into 8 Altec 515's. I don't quite get it...............



Guy