My first Altecs - 604-8H

**Toph** · October 8th, 2014, 08:52 AM

Originally Posted by cradeldorf

Are those even alinco? I thought they were ceramic by that time? I won't give my opinion on sending them out but you should have just ordered the phragms and put them in yourself. they just drop in and paying to ship them to GPA is gonna kill ya.

everything I've read said these are the last with Alnico, and first with the Mantaray Horn.

I like the peace of mind knowing the magnets are up to spec and diaphragms installed correctly. Especially if they may be taking the place of my beloved JBLs!

**juniper** · October 8th, 2014, 02:49 PM

Welcome to the board Toph! Great purchase! 604's are great speakers with the right amp and source. With piano music and strings, I haven't heard better, with a good recording. I have 8g's with tangerines, and H's with less than 10 hours on them per the original owner. I haven't hooked them up yet. I would like to hear your impressions compared to your jbls. I have heard some very nice jbls and the clarity of the Altecs with the right recording can keep up with them.604's with some music, give my 19's a lesson in respect, but with some types of music its the other way around. Good luck!

**Altec Best** · October 9th, 2014, 01:31 AM

Originally Posted by Toph

everything I've read said these are the last with Alnico, and first with the Mantaray Horn.

Right and Right again.. They are the last alnico version and the first with Mantaray horns.

GM · October 10th, 2014, 02:24 PM

Originally Posted by oface1

Thoise cabs look like they're 612's.... I might be wrong though.

Or right, they look like either early Lansing 612 or copies, but have no access to the drawing to post to compare to.

GM

**Toph** · October 10th, 2014, 03:30 PM

Originally Posted by GM

Or right, they look like either early Lansing 612 or copies, but have no access to the drawing to post to compare to.

GM

They appear to be "loosely" based up 612's...

either way...big and ugly.

I've got some cabinets that are just shy of 5 cubic feet. I plan on using these until I can build some StoneHenge V.

What type of vent/porting do I need to do? How low should I expect the 604's to go in that type of cabinet? And will a 5 cubic foot cabinet be harmful to the drivers?

GM · October 11th, 2014, 02:23 AM

Yeah, the early utility cabs I've seen were varnished commercial grade plywood with a basic inset rectangular grill with no cosmetic pretense.

The rule-of-thumb is that with up to a ~0.403 Qts, driver Vas = net Vb and Fs = Fb, so that's the size limit for having a flat frequency response down to Fs, ergo any smaller means a higher F3, Fb, which of course allows a greater power handling with an increasingly smaller cab tuned higher.

The question then is how big can you afford to get the desired bass response once any room, boundary gains are factored in.

I currently have no access to all my tech data, design programs, etc, so can't answer the other Qs for awhile yet beyond that a round vent is always the most efficient, ergo any other shape will require a longer vent for a given Fb and that a simple vented box program can't accurately calculate a high aspect ratio cab's vent design, such as a V5 or what we now call a mass loaded [vented] transmission line [MLTL].

For a max power handling vented alignment down to Fs, you can use a sealed box program to find the cab net Vb that tunes the box to 1.56x Fs, then empirically find the vent length of a vent area [Av] = at least o.25*driver Sd; though without a lot of room, boundary gain, bass will be limited pretty much to a strong mid-bass.

GM

**Toph** · October 16th, 2014, 02:19 PM

The speakers arrived at GPA safely yesterday!

can't wait to get them back.

I've been told I should recap the crossover. I figured this would be a good project while I wait.

I've never done this before - can someone point me in the right direction?

P.S. it is the 604-8H crossover

**Altec Best** · October 17th, 2014, 11:48 AM

Can you post photos of the internals ? But basically you just swap out component for component. Take lots of closeup photos or draw a schematic or do both..It will help you put them back together properly.. I would change the Capacitors,resistors and the wiring..Leave the inductors ! They very rarely go bad and is a waste of money IMO.