Film-Tech Forum ARCHIVE: altec HF driver general info

This is topic altec HF driver general info in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=010182

Posted by Jeff Else (Member # 4063) on 11-20-2009, 08:29 PM:

what is the difference in terms of performance between the following:
802-8D
802-8T
902-8T

i see that the 802-8D looks much older than the similarly sized 802-8T. any perfromance difference or are they the same if outfitted with new diaphragm voice coil assemblies? the 902-8T is lighter and smaller, but takes the same diaphragm, and looks to be of similar vintage to the 802-8T. whats the difference?

Posted by John Walsh (Member # 168) on 11-20-2009, 09:59 PM:

Steve is putting down those small cubes of cheese and will begin typing shortly ....

Posted by Steve Guttag (Member # 268) on 11-20-2009, 10:12 PM:

Normally, as Altec changed their driver in any way (including just a diaphragm change) it necessitated a change. Sometimes it also differentiated the impedance.

I think you will find that the 802D versus the 802T was the phase plug (radial "tangerine" versus concentric) The 902T would be Ferrite versus the 802. Mind you, I'm less up on the 800/900 series drivers than I am on the 288/299 series or the 15" LF drivers.

Steve

Posted by Jeff Else (Member # 4063) on 11-21-2009, 02:24 PM:

what does the radial phase plug do? what, if any, is the advantage of ferrite?

Posted by Steve Guttag (Member # 268) on 11-21-2009, 02:43 PM:

The radial phase plug increases the HF response...I know of no negative attributes of it.

As for Ferrite over Alnico...the only "advantage" is that a ferrite magnet is permanent...and Alnico can loose its charge (but can be recharged). From a service standpoint, the Alnico has an advantage since it can be discharged, disassembled and fixed, reassembled and then recharged.

Sonically, you'd be hard pressed to do a double-blind test and have any real meaningful results.

Steve

Posted by Jeff Else (Member # 4063) on 11-21-2009, 02:53 PM:

i see, thanks!

Posted by Jeff Else (Member # 4063) on 02-10-2010, 03:17 PM:

i have an assortment of these drivers, 3-802-8D's 2-802-8T's one 902-8B, and one 902-8T. i really don't know much about the condition of the drivers, some seem to sound better than others, and a couple don't make any sound. what would be the best 3-channel configuration of these, and where can i have them tested/repaired as necessary, and how much might i be looking at spending? i love the way these sound, and i think they are a good fit for the auditorium which is a little under 40' long and seats 120.

Posted by Steve Guttag (Member # 268) on 02-10-2010, 06:49 PM:

I would probably use the 902-8T in the center and the 802-8T on L and R...re-diaphram all either with Aluminum or Pascalite diaphragms (probably Pascalite for better power handling).

Steve

Posted by Jeff Else (Member # 4063) on 02-10-2010, 11:26 PM:

are these still made new? where can i get them? it it a matter of simply (and cleanly) slipping the new diaphragm assemblies into place or is there more finesse/technique to it that would require experience?

Posted by Steve Guttag (Member # 268) on 02-11-2010, 05:18 AM:

Yes, they are still made new. Though not ment as a pitch...we do stock them at Cardinal Sound & Motion Picture.

Installation is quite easy. The biggest thing you need to do is ensure that the air gap is clean of all metal particles that may be stuck to the magnet structure (use masking tape an something like fish paper to pull the masking tape around). If it is clean, the new diaphragm shouldn't have any problems. You will likely also need a diaphragm kit to switch from screw terminal, to push-on terminal (on the diaphragm itself, not the back cap). Some prefer to solder the wires instead of changing them to the push-on...just don't over-heat it.

Steve

Posted by Jeff Else (Member # 4063) on 02-11-2010, 03:14 PM:

locally i have found an excellent deal on MR94A horns. i've heard a lot of good things about MR94's whats the difference, if any?

Posted by Steve Guttag (Member # 268) on 02-11-2010, 06:04 PM:

I want to say it is in the throat and 1-piece versus 2 piece...but I could be wrong there. The MR94/MR94A is the best 90x40 constant directivity horn...ever. Note, they are for the 288/299/399 series...not your 800/900s.

Steve