Rightio. I've never seen one in the flesh, so I now know!Originally Posted by bowtie427ss
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Really hard to day. Sonically the GPA will be great.
The 8G is a desirable 604, mind you so are most AlNiCo things Altec.
The cabs themselves have a value, and if cared for and in good nick, could make you money.
There is not a lot of GPA stuff on flea pay yet, but it seems to hold value.
Im not sure how these drivers work exactly but the HF section is said to be very fragile. Even with the 3khz xover. I like the idea of having a beefy 802 driver built right in.
Its my understanding that the 604 is a 515/802 and the 605 is a 416/806. Im not sure what the other 60x are based on.
I am also interested in the newer PAS, Renkus, and Radian "coax" drivers. I would like to find a cheap pair to play around with
From my experience the C/D era was like this.. The C had a paper surround cone part no. 20598. When the C was discontinued in catalogs around 1957 to push the 605 for home use, there was an outcry from studios. To meet this commercial demand Altec put together the first generation D duplex speakers. They used NOS 20598 cones and labeled them as D. I have a D that has a new part number on the cone for the D, but hidden behind one of the spokes is the 20598 number verifying to me that it is a C cone with new numbers on it designating it as a D. The early D's were pretty much identical to C's. Then as they morphed into the later D, the spider was changed, the voice coil was shortened (too give it a deeper throw) and the cones were changed to the accordion edged style as seen on the next generation Duplex "E". So essentially an Early D is same as C and a late D is same as E or very close to it. Currently the only re-coning options available for an early D or older speaker is to have it re-coned using the later accordion edged cone. While this will work, it will no longer perform like a C. I have original 606 cabinets and they were designed specifically for the C, so by example if I were to mount a late D or any other later duplex the port would have to be tuned specifically to that speaker. Many have tried to say that the 604C paper edged cone is the same cone as used in the 515a. At this point I can't verify this.I recently aquired a pair of empty model 17 (620) cabs. I have been looking on the 'bay at different 604 models. Please help me understand which is the best value for the performance. Please post any corrections to my notes. I posted this over at AK first but did not get many responses.
604-RWB
Looks like the first gen. Paper surround. AlNiCo magnets. Too expensive for me
604-B
Looks the same as above
604-C/D
Same as above except they switched to cloth surrounds. This is the generation (or G model) I would like if I can find a deal
Correct, a N3000 [super] tweeter, which is a little horn loaded microphone diaphragm, so quite 'transparent' sounding and very fragile with no user replacement parts and seems like there's either no more diaphragms and/or the guy that was repairing them is no longer in business, but not sure.
Some folks really like them, but I'm no fan of using woofers over such a wide BW, so for me would only be fine for AM/FM Muzak type systems.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Hello,
Well, I find this thread to be very interesting, I have been wondeering about all of this for some years now. Thank you, for all who have contributed !!
My friend and audio mentor uses the GPA 604, and he tells me, in his opinion, they are the best 604 ever, due to their magnetic design primarily. . " Well, its NOT alnico, " I tell him. He says, so what !! He points out that with a ferrite magnet, the magnet is CENTERED around the voice coil gap, it does not have a huge offset " U" shaped magnet structure, on ONE side only of the voice coil gap. In a way, he seems to be suggesting to me it has symmetrical magnetic drive, and it is engineered that way, as a design advantage. He feels, all the GPA 15 inch, etc, drivers have this advantage.
He is the only person I have heard this from. He uses the GPA in his company's 604 MLTL speaker offering, and at home, in his home system.
Anyone familiar with this, care to comment and verify or dismiss it ?? Thanks in advance.
Low Ohms.....Jeff Medwin
Hmm, all drivers have a ~symmetrical magnetic drive AFAIK since the VCs are centered in the gap, hence the ease of calculating the [Xmax] spec. Anyway, look at Klippel measurements to see how much real world offsets can be, though seriously doubt there's been any done on Altec drivers or even AlNiCo for that matter. I'm sure these folks can provide you with all the tech info ya'll can handle on the subject.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
You are not quite getting what my friend was trying to tell me. Yes, voice coils are centered in the gap, but the alnico has a U shaped structure, essentially all on ONE SIDE of the voice coil gap. A Ferrite, latest from GPA, has the magnetic structure, NOT hanging on the rear of the driver, but rather, in the same plane as the voice coil gap, with a equal magnet structure mass, on each side of the voice coil gap.
The Alnico magnets look annular/concentric to me. Nothing sticks-out to one side.
Altec Lansing DUPLEX(R) Loudspeaker Systems
Opinion is only as valid as its verifiable supporting evidence.
Oh,I'm getting it, but based on my experience designing various electric motors with AlNiCo, Ferrite, Cobalt and Samarium Cobalt, all of which each has its own 'quirks' WRT orientation in relation to the coil or armature among others, just don't believe these differences he's noted is anything beyond each being optimized for the material, etc., differences.
The bottom line for me is that the AlNiCo motor is the better performer overall, though not necessarily over time and that to improve on it will require a new design using Neodymium.
Again though, pretty sure the Klippel folks can get to the bottom of it.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
From what I have read it seems the 604 8gs are the best bang for the buck, and sound really good. I know I adore mine with great recordings, so much depth, power, delicacy and imaging that is second to nothing I have heard. Plus you get to loan them for free, buy them use them sell them break even or come out ahead.
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