GPA 604/Iconic 704

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Greets!

AFAIK they are one and the same, but best to ask GPA just to make sure. Regardless, the ML-horn I did for Jay Fisher has enough net Vb to accommodate a variety of specs since it was designed for his ~matching (high output) impedance amps. Jay's wife is expecting twins, so this project's on hold for him, though he offered to do any changes to the drawing, so I need to get back to him, but here's the basic unfolded, bottom vented design, ergo would need to be spaced up a bit:

GM
 

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The Iconic 704 differs from the GPA 604-8HII in the power handling. Iconic uses high temperature voice coils and the higher power alloy aluminum diaphragm in the HF.
Despite protest from those who believe otherwise, the sound of the two is identical, the HF diaphragm sounds and measures identically to the older duraluminum unit and handles 2 1/2 times the power. The LF voice coil has exactly the same number of windings and winding length, just is made with high temperature glue and on a high temperature former instead of a paper one the GPA uses.
The last of the A/L 604s had an overdamped LF section, the current motor setup was designed by Iconic, which releaved this condition and increased the linearity was adapted by GPA in their model also. Yes, there are some differences.
 
064/704 specs

I down loaded and printed the spec sheets for both drivers, all specs are exactly the same, look like the same exact spec sheet with a logo change, so the drivers must be identical. GM, I have a pair of 416's, what would be the feasibility of doing a 2.5 way with the 604/704 and a 416 sharing an enclosure?
Jim
 

GM

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Joined 2003
You'll probably have to use some form of series resistance to balance them out, but I don't see a problem beyond possibly requiring an even larger cab than posted depending on the 416, amp(s) used and desired performance goals.

GM
 
Iconic is getting it together to get the website and specsheets changed, as you can tell, the spec sheets, Iconic's and GPA's were done by the same person, Iconic's was first. The power handling of the 704 sheet is a mistake, it ought to be 140 watts AES. The woofer to use with the 704 is the Iconic 164, which we do not yet have spec sheet on, it uses the same LF topology as the 704 and is the same efficiency.

Watch for changes soon.
 
These units will be used in a room that is 15' wide by 30' deep, with the speakers on the 15' wall. My desires are speakers capable of wide dynamic range without losing low level detail. I listen to a pretty wide range of music, although I tend to gravitate more toward accoustic and classical. They will be used for the occasional dvd (concerts mostly with a movie every now and then). They will be driven by pp 300b amps. At present, the speakers I am using are some 80's vinatge MTM Polks with stereo subs. At lower levels, they sound quite good. Originally, I had contemplated the 604 in a mltl type of cabinet (I am taking the mltl idea to be a variation of a reflex box with a taller, more narrow profile than a more classic reflex design). I have a pair of 12" wide range drivers in this style of enclosure in my office. While the drivers are not high end (modified eminence), they offer a dynamic range that is impressive, even at low listening levels, and the imaging is very good. They offer a certain coherence and dynamic ability that I would like to refine, hence my interest in the larger duplex driver in a suitable enclosure. The idea of using the 416's as well stems from the fact that I had them left over from another project back in the 80"s. They are actually doing sub duty at present, living in 3cf ported boxes with a plate amp. They do a surpisingly good job, better than other commercial subs they have been compared to, although in my application, sub duty isn't movie effects, rather more like the last octave of a string bass or the thump of a kick drum.
 
Hi JimW,

I have beeen looking at a similar option as you with using the GPA 604HII as a monitor mated to a good subwoofer to reduce cabinet volume needed. It would take a 10 - 12 cubic foot cabinet to get down low with the 604HII in a single box sollution.

My listening / livingroom dimensions are 15' x 25' x 10', just to crowded to accomodate a 10 foot box. I was trying to keep the foot print of the box to 18" with a total of 6 cubic foot volume including subwoofer.

Here is an email from Jeff Markwart with dimensions for a satellite cabinet for the 604HII, copied and pasted below.

"I plugged the 604-8HII T/S parameters into WinISD and it suggested that a 3.9 cubic foot enclosure with a 10.25 square inch vent area and tuned to 49Hz would be flat to 100Hz and would be -3db at 58Hz."

Here is a link to his website where you will find many crossover designs, to include one for the GPA 604HII driver.

http://home.earthlink.net/~jmarkwart/

I hope this helps?

NW
 
Norris Wilson said:

"I plugged the 604-8HII T/S parameters into WinISD and it suggested that a 3.9 cubic foot enclosure with a 10.25 square inch vent area and tuned to 49Hz would be flat to 100Hz and would be -3db at 58Hz."

Greets!

FWIW, This alignment assumes a SS amp's vanishingly low output impedance, so if driven with a high output impedance amp the cab's Vb will need to increase, possibly significantly. Also, this size vent's 'speed' is a bit high, so may 'chuff' if driven hard.

Regardless, in such a two way you would normally either set it up so both drivers occupy the same air 'spring' or put the 604 in a sealed separate chamber (or cab), but this Altec Japan spec studio monitor has a separate vented 604 chamber, so as always YMMV (scroll down to model 6041): http://www.fsinet.or.jp/~ash-k/alteccatalog.htm

GM
 
JimW said:
So could I use a 604 and a 416 in a 9-10 cf enclosure, with the chamber area shared? That would make possible employing both drivers in an enclosure that will not upset the waf.
It may have been done before, but I see no good reason why you would. Even crossed out to the 604, then the 416 will modulate the 604's cone via box pressure.
 
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