Which Altec 15" equals the 604E or K 15" ?

[Xhorxhi]

Do one or more of the 416-21 or 515 series woofers roughly corespond or mimick the woofer in the 604 duplex speakers? Further than T/S params do one of the stand alone have a similar sonic signature compared to the 604's woofer component?
-Chris-

[Xhorxhi]

As an adjunct to my above question I'll just spill the beans here!
I have 2 808-8A drivers and I'm quite certain (even though they work "OK") that the diaphragms need replaced since the things were in A7's and run without the crossovers for a rock band's sound for many many years. Now my thinking is that since a 34647 diaphragm can be installed in the 808's per the Great Plains parts "notes" #13 that this would effectively duplicate the high freq. signature of a 604e or 604k with the right horn flair. Is my thinking correct on this? Since the 604 is so very praised (albeit expensive) if I can get the high frequency "just right" with the 808's
then the next step is a woofer that mates well at the 1500Hz crossover of a 604. The only difference is that the high freq. will not be eminating from the center of the woofer. Perfect point source be damned I just would like to duplicate the signature of the 604 duplex even somewhat. Ultimately my goal is to put said woofer into a half width Jensen Imperial horn like this and include the 808's with the 604 diapragms (part#34647) and an apropriate horn to achieve the 604 sonics! The jensen Imperial is a proven design and it works well with almost any 15" driver. I noticed that many of the Altec woofers have the Low Qts parameters to mate well with large bass horns like the Jensen Imperial. As for the half with it has ben done with great result and no loss in low frequency extension.
So to sum up can a separate Altec 15 and 808 with the 34647 (604 duplex) diapragm get close to the 604E or 604K?

[selmerdave]

Chris,

Nice to see you over here. I think (although there are many here considerably more knowledgeable than I) the 604 is basically a 515 LF with an 802 HF. Which incarnation matches the 604E I'm not sure, perhaps it's the 515E but they don't always work that way. The diaphragm should be the same (I think) for both the 802 and your 808, I believe it's mainly the magnet structure that differs.

Having said that if you're not going to have the point source, you can probably do better than the 604 anyway. You might as well lower the crossover point to 800 or 500, depending on the horn you will have. The 604 is a tradeoff that it gives point source but the size of the horn is necessarily limited (to allow the sound from the woofer) and thus the high 1500 hz crossover point.

You may get responses here steering you away from horns, but the 515 has the strongest magnet and I believe the lowest Q so it would be seem to be the best match. But honestly once you've got a set of 515's and a pair of horns you're at least at the price if not over for a pair of 604's. It really comes down to which you would prefer, each has it's benefits.

I've considered the same thing but pairing a set of 515's with my 604's to get a lower impedance, but I'm not in the position to build monster cabinets right now (not to mention having a doorway to get them through).

Best of luck.

Dave

[Xhorxhi]

Thanks again Dave for your insights. I probably should call Bill at Great Plains and have a chat first before jumping in with both feet ehh?

[Xhorxhi]

Well Dave, what a surprise!
Nice to see you here as well and thanks for the response. I guess we can continue this over here then instead of at Decware.
Apparently the later versions of the 604 like the "G" and the "K" with the Manta ray horn are the most "raved" about as far as "real"sounding and super top notch Studio performance. These (604G & 604K) seem to be fetching from $1,000 to upwards of $1,500 per pair on Ebay. I know I can do better than that if I'm patient on Ebay with. I do think the 515 woofers of an 8ohm variety will be the toughest thing to conquer if indeed that is what I need to somewhat "duplicate" the "tone" balance of the Duplex. I have seen the rear chamber cover of a 604G and indeed it is the more "modern" one like the 802 driver, but the more vintage 604s have a high freq. driver body like the older style 806 and 808 drivers. It is encouraging to note that the 34647 aluminum diaphragm works in the 808 in place of the "symbiotik" diaphragm which I assume was for more commercial high power and sound reinforcement use. I understand from some reading on the web here that that "symbiotik" diaphragm has not much upper extension and the mids are harsh at close range. The 808-8A's I have did com out of AOTT A7's so that makes sense. I'm thinking that a diaphragm upgrade will at least get me a solid foundation in the general direction of "604ness". I really should hear some 604's first but I know of no one close by that has them. Some research on another of the finest Altec hifi speakers, the much lauded Model 19, has revealed that although the 19 uses a 811 horn and an 802 8ohm high freq. driver, the Altec folks chose a much higher 1200Hz crossover point than normally used with the larger Altec horns. Apparently letting the 416 in the Model 19 to cover the midrange gives that speaker its favorable signature. My thinking is that if the 604Duplex's crossover is 1500hz and the Model 19's is 1200hz (as opposed to the more common 500 or 800 crossovers used by Altec) then a big horn like a 811 or 511 is not needed. More like an old 32A horn or even a DIY home fabricated Manta horn like on the 604K mounted on the baffle as close to the 15 incher as possible would do well Yes? So this avoids the cost of buying the horns. I just need to get my hands temporarily on someone's 604K to take some measurements on the horn dimensions if I were going to make one (manta horn) properly. My next thought was that since the Imperial is so damned good with just about any 15" that I may not need a perfect 15" for the job. The Imperial loads a driver so consistently and the driver unloads more gradually with horn loading vs. a more conventional ported box that the freq. response of the 15" would smooth out real nice with good control and nice tight low "extension".
I know it sounds like I've got myself talked into this but I still need someone to bounce these ideas off of who at least has heard the 604! BTW the 416 is the 15 used in the model 19 and many other of the "home" audio versions of Atec and the Qts while a bit higher than I'd like for bass horn use might be easier to get. My first concern is getting the bulk of the sound right and that would be to see, or more rightly, "know" if an 808-8A retrofitted with the 604 Duplex diaphragm (#34647) will indeed get me the sound I need from the "raw" driver. The horn flair can be solved a number of ways.
So after all this drivel now what do you think Dave? Anyone else?
Thanks again,
-Chris-

[selmerdave]

As far as the diaphragm, go with whatever Bill tells you. If he says it's the right one, do it. As far as the casings of the various drivers, that has more to do with the magnet type and vintage than anything. The more "modern" style casing that you describe started with the 604E2 I believe, and the 604-8G also has it. The 604-8K has ceramic magnets and it's a little different. That's just looks anyways, you'll find the same thing with the HF drivers.

As far as the 604-8K or 8G being the ideal, I'm not sure. The 8K with the ceramic magnets is really quite different I think, with considerably higher power handling (and heavier voice coil likely). I know there are many posters here that stand by the 8G's, but to some the 604E is the ideal LF cone and to some the 604B is the best overall. I certainly haven't read too many people's opinions here in favor of the CD horn over sectoral (for hifi). Rather than spend too much on the "ideal" I'd go for whatever is in your area or is at the right price, I have a feeling they're all pretty darn good.

Dave

[RonSSS]

Hey Chris,
Jensen Imperial Folded Horns! Thanks for the memories, those things rock. Haven't seen any of those since the early 70's!

You should be able to compare T/S parameters of the various 604's with the 515's and the 416's.
The 604-8H appears to have the largest QTS and the 8K the lowest.
But since you haven't heard either of these, I suggest you just pick the Altec Woofer that best matches the box.

For the HF, 808's were just a symbiotic version of the 802 I believe. A simple diaphragm change will get you what you want.

Altec sold just the mantaray horn version of the later 604's as a seperate. The part # is MR902-16HF.
http://www.lansingheritage.org/image...ro/1993-28.JPG

In my opinion, using one would be way too small for your setup. Consider either a 511 or the similar sized Mantaray horn that can be used with the small format drivers. MR994A

http://www.lansingheritage.org/image...ro/1993-27.JPG

Have fun!

Ron

[Xhorxhi]

Thanks Ron for the great tips & links. (Sounds like breakfast HAAA)
As for the Imperial recall I said 1/2 width! So that would mean the speaker pictured in the link I posted above cut vertically down the center and only one 15" and a horn tweeter low on the baffle.