Quote Originally Posted by J Henry View Post
I've been reading a lot of threads about 604's lately & it occurred to me....why do they sound so good when all the theory says that they shouldn't?

I mean, most say that 1500Hz is way too high to cross over at.....that you need multicell horns or the big radials or Mantarays to get the best sound from the top end driver......that 2 inch, or at least 1.4 inch, is superior to 1 inch throat drivers. The odds just seem to be stacked against this speaker, yet all reports are that it is a fine sounding unit.

With regard to the actual driver....is it a 416 driver?....and what is the top end driver...a 902? an 802?

Just curious to see what yars think.

I had a very interesting discussion with an EV engineer once. When he finished measuring the 604-8G for AcoustaCadd, he called to tell me how bad the coverage measured. He then went on to say he thought the 604 sounded wonderful.

This story is to illustrate a couple of things . . .
First: You will not know what a speaker sounds like from looking at the specs
Second: The 604 is a near-field monitor and sounds best from 10 or 12 feet away

"1500Hz crossover is too high"
The LF of an early 604 is very similar to an early 515. Later the LF was a bit of a combination of 416 and 515 (per an Altec engineer in OKC, about 1990). The 416 and 515 have very light moving mass and are relatively "fast" or accurate when a signal is applied. They are fast enough to stay up with the 802/902 at 1500Hz and deliver a warmth that would be missing at a 1000Hz crossover. This lack of warmth in the HF driver is likely a function of the very small horn.

The A7-500 gets away with the same type components crossed over at 500Hz. I suggest the much larger HF horn is supporting this success. I also would point out that a stock A7-500 is very "fat" in the mid-range and needs lots of work before it is usable as a hi-fi speaker. Not so with the 604.

604 Duplex vs Two-way . . .
The biggest issue here is that the ear can easily detect, from 10 feet away, that there is a distance between the HF and LF on a two-way system. As you get a further away this is no longer an issue. The 604 Duplex has the HF and LF sources together.

"that 2 inch, or at least 1.4 inch, is superior to 1 inch throat drivers . . . "
As with most things, there is some truth in this thinking. At high sound pressure levels the 1" driver starts to break up and distort before the larger driver. Some people have morphed this into a flat statement that the larger driver is better. My comment is; it depends. A larger driver is my choice when high SPL is needed. If I were building a home hi-fi speaker and was bound and determined to use a 500 - 600Hz crossover, I would want to use a larger HF driver on a medium-to-large horn. My A700-8A speakers are loaded with 902/515G and crossed over at 1200Hz.

Many people base their beliefs on facts that sometimes do not apply to the need at hand. Others are simply defending their decision to use this driver and that horn.