904-8A 411-8A system

[RonSSS]

I put this setup back together again after I don't know how many years! A problem with advancing age.
The M19/8184 Subs system is on the other end of this room.
The 904's do have the GPA alum frams. Xovers are stock config but do have some ZEN caps in the HF section. I managed to lose the orig 6uf caps.
It sounds quite good, but not great. My guess is the PA aspect of the woofer cones. I never did get around to having GPA recone to I guess the 604-8K cones. Was never sure if an 8G cone could go in these.......and what I gather is I'll never know.

The 411's here were the first pair Bill did.
Orig cones were toast.

Nice they got the site fixed......again.

Ron


904 System.jpg

[Steve Mac]

I put this setup back together again after I don't know how many years! A problem with advancing age.
The M19/8184 Subs system is on the other end of this room.
The 904's do have the GPA alum frams. Xovers are stock config but do have some ZEN caps in the HF section. I managed to lose the orig 6uf caps.
It sounds quite good, but not great. My guess is the PA aspect of the woofer cones. I never did get around to having GPA recone to I guess the 604-8K cones. Was never sure if an 8G cone could go in these.......and what I gather is I'll never know.

The 411's here were the first pair Bill did.
Orig cones were toast.

Nice they got the site fixed......again.

Ron


904 System.jpg

Goodness, that’s a beautiful looking setup. Congrats!

[RonSSS]

Thanks Steve, not sure if I'll ever get them sounding beautiful, but I'll keep rubbing on them......

[RonSSS]

After further review, and some basic setup, I'm quite pleased with this setup.

I dug out an old Stereophile test CD that contains in/out of phase track, left/right track, pink noise track, and warble tones from 2khz down to 20hz.

Discovered I had right and left mixed up, doh!
Discovered I needed to swap the polarity on the sub woofers, they were out of phase with the duplexes.
Using the pink noise discovered I needed to re-toe the duplexes to eliminate at least some of the comb effect at higher frequencies. In other words, broaden the sweet spot.

I also flipped the duplex boxes over to get the horns just a bit above ear level. Now I have to rotate the crossovers as they are upside down now.

Of course, lastly, dialing in the MF/HF pots on the crossover. My goal is to not "hear" the horns. Just to blend them with the woofer.
That said, I'm not hearing ills of the "high power cone and VC".
We know it's an R904-8 and is also used in the 604-168X, but only a handful of folks know the exact difference and they aren't talking.

Oh, I drew out the crossover. I removed the switch system that allowed the MF only control, so now it operates just like the M19 but of course is different. if interested, I can post it here.

Ron

[LOUDER]

ron, after a bit of research, the 904 seems to have the same high power voice coil as the 515 8ghp the specs are similar. and all the recone kits are interchangeable. but it sounds like you have gotten everything sorted out. enjoy!!!!

[RonSSS]

My inside source, who has spoken to Bill, says no more recones and no more cone kits. Even though the website says different.
So, the point is moot.

If a guy had a dead pair of duplexes, I suppose you could try an aftermarket cone. I’ve never heard any first hand reports on those.

We have a great reconer here. They put my GPA cones in my 416-8C. I may stop in and have a chat. They were a factory authorized Altec service shop back in the day.
They reconed one of my 419-8B biflexes that I dropped a tweeter through. 😊 Didn’t even charge me.

Thanks for the comments.

[LOUDER]

ron , what are you running the 411's at ? From what to want ? Just curious ?

[RonSSS]

70hz and below. I built a Linkwitz Riley 24db/oct low pass that goes ahead of the Kenwood.

The 904’s are 3db down at 70hz.

When GPA reconed these, I measured the TS parameters and they came out closer to a 416. Way different from a stock 411. So they work fine in a ported enclosure.