904-8a conversion???

[oface1]

Hello all,

I have found a set of duplexes for $500 a pair + shipping in working condition/ no XO's or cabs.

He says the surrounds and phrams are good.....The few pics seem like they are good...

I have not bought them yet, with the reason that they are different in model numbers.

One is a 604-8h and the other is a 904-8a. Can I convert the 904 to a 604-8h or equivalent?

There is very little info on the 904, and I told the fellow that I would research it and I am left asking you guys , would you go through with this?

I have been itching for a 604 project and this like a good deal......


Thanks,

-chris

[bfish]

Sure a tempting price Chris.

604-8H is AlNiCo, and 904-8A is ferrite, so conversion for a matching pair's out.

[oface1]

Well,,,

I am confused with the pics he just sent me.....

I am not doubting you one bit....

I swear the 604-8h is ferrite................maybe it is an angle, lighting, or not.....

?are there some ferrite 604-8h's running around like little bastards? or has this had a label change maybe at one point or was it a oops at the factory?

here's my link to my flickr account,,, from the photos it looks like ferrite to me,,, but I might be wrong....

Flickr: denied6969's Photostream


any help will be appreciated fellas.. I am itching at the bit...


Thanks,


-chris

[GM]

Indeed it is, it looks like a 604-8K........ WRT a cover/label change, what's the 391xxx date code on the frame?

GM

[bfish]

Yeah, both drivers in your pics are ferrite (but the only Altec 8Hs I've seen weren't). Methinks one (or maybe both?) the rear caps with decals may not be original/correct.

Added;
Both cores appear to match, whatever they are, so worst case, 2 recones could yeild 604-8Ks.

[RonSSS]

Hard to say what the 604-8H really is. all it takes is a rear cover change and you have a new speaker!

That is clearly ferrite. Could be a 604-8K.

The diff in the two are the cones (can he photo the cone numbers?) and the HF diaghpram (can he remove the covers and photo them as well?)

The 904 had the symbiotic fram......kapton surround. It's very obvious. The 604, of any variety had the all metal surround, except for the 604-HPLN which was actually a 904-8A.

I have a pair of the 904-8A that I changed HF frams in, removed the loading caps, added felt to the covers and they are WONDERFULL. The LF cone is made to handle more power, but they still work well in a home hi fi setting.

For $500, go for it. I paid $400 for mine, and another $200 or so for the kit from GPA and have never regretted it.

Ron

[oface1]

Man, I was scratching my head there for a while, cause I kept telling myself that is ferrite, but maybe I am looking at it wring, I know what happens when you assume.........


So should I jump or not? worth the risk?

After I went over and over on the pics,, It seems that there was a cover/label change at one point........

hmmmmm,,,,,


Thanks fellas...


-chris

[Old Guy]

Here's my dime...two cents adjusted for inflation.

I suspect a pair of 904's.

Check the cone numbers as suggested.

The coating is probably a waterproofing treatment.

And as suggested...check for 391+ numbers, the numbers after 391 identify year and date.

Assuming 904's you'll want to do the mods to the HF, Ebay the original frams. Do a board search for 808's here, same mod.

Since they both have the coating and look so similar, the most logical explanation is the driver cover was switched.

The 904 cones are not bad, especially with a sub. IMHO they actually have more mid bass than the 604 cones.

All in all I'd pull the trigger. If unhappy, sell them at a profit on FleaBay. But I suspect they will be usable as-is, better with HF mods, and VERY nice with a sub.

YMMV.