Experimented with 604E in scratch built A7-500 (825 cab) tuned to ~40 Hz using 3/4" marine grade ply and extra bracing. Horn section damped with kitty litter. Wound up lining the top inside of the flare with a thick foam and putting the HF horn mounting angle back on to brace the top. Sounded pretty good to us, but worked even better as a three way with the 511, though the owner ultimately put them in a false wall IB with 515B 'helper' woofers which was best overall.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
You may want to ask Analog Addict as he is running a pair of 828's/604's now I think, maybe he can give some help.
http://www.hostboard.com/forums/1834553-post1.html
Will the ferrites fit without modding the back panel?
Easily. The ferrite 604's are about the same overall depth as a 515B, give or take a 1/4 inch. The alnico 604's don't interfere much, about the depth of the HF cover, just enough that you have to modify the back panel to accept them.Will the ferrites fit without modding the back panel?
Not all vegetables make good leaders.
Interesting, the rear mount published dims says that it would be a press fit in the 825 and too long for any 828 or clone made from 3/4" or thicker material. Only one way to know for sure though.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Hmmmm..... I have a pair of the ferrite 604s. They are too deep for my cabs. Not by much, just enough. Could be some of the 828 cabs are a bit different?
I'll be over at Analog Addict this afternoon. Don't know if he has the 604 rig running - I'll let you know!
My experience was with 904's, shouldn't they be dimensionally the same as a ferrite 604?
Of course it now occurs to me that the 904's may not have had traditional rear covers, only loading caps as i seem to remember them having the same style loading cap as the 902's on model 14's. That would certainly reduce the depth by a good 1/2 inch vs a driver with HF cover in place. It's been a while, and i never spent a lot of time looking at the combination internally, but i do positively remember the backs being properly installed with no holes in them.
Apologies if i've sent anyone astray.
FWIW, there should be ~8-1/2 inches between the inside of the back panel, and the mounting surface of the woofer baffle of an 828.
Not all vegetables make good leaders.
Is there no concern for the HF diaphragm being modulated or even damaged by being "contained" in the LF pressure zone?
"[I]We're going all the way, till the wheels fall off and burn[/I]!"
Bob Dylan, from [I]Brownsville Girl[/I]
[I]"Time wounds all heels"[/I]
John Lennon, referring to the Nixon/Hoover deportation fiasco.
Again, interesting since the published specs actually show the 904 being 8-7/8" when rear mounted Vs other Ferrites including GPA's as being 8-3/4". Can't say as I'm surprised though, Altec's marketing dept. was already getting pretty sloppy by the mid '70s. You're right though, with loading caps only they should at least fit the 825 and if yours fit a 3/4" thick construction 828, then seems like even a regular rear cover would at least mild pressure fit any of the 5/8" thick cabs, mass loading it to be cab.Originally Posted by bowtie427ss
Sounds like we need some folks to measure the various models to see what they really are.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Thanks to all, and by all means continue!!
GM,
Regarding your comment on using foam on the flat horn top, would it make more
sense to slope the top so it is symmetrical with the horn bottom surface,
equalizing the angles so the expansion remains the same? I assume this is all
intended to stop the cabinet horn from reflecting vertical spill from the small
HF horn on the 604C.
I wonder what the comparability of the VOTT is to the Tannoy Autograph/
Westminster, at least in front of the driver.
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