My A7-500s. A journey

[Panomaniac]

Hey John - yes, I'll get them there. And I'll be smiling!

Scott. Right on. Flat just does not sound right. That's one of the reasons my "home made" Altecs sound better. I tuned the passive x-over by ear and pulled the mids down. Doing that makes listening to them close up a lot more pleasant. I just wanted to start the A7s as flat as possible for a reference. Doesn't sound like they will end up there.

I'll post x-over schematics, photos and impedance curves tomorrow for the technically minded reader - and those who just like pretty graphs. =)

Here is the stock N-501 crossover schematic. There is a typo in it. That should be 3mH, not 30! I'll revise and repost.

[mah]

I found this crossover schematic but I don't know where it came from.

Possibly from here:My latest DIY speakers - Club Polk

[Mustang Marvin]

Pano,
Thanks for this thread. I have just completed my A7-500 project. I posted some of the restoration in another post. Mine have 416-b, 902-8t, 511B, and 800HZ Eminence XO.

I had the 416-8B's re coned by GPA. They also recommended that I reduce the port size for home use. This tuned the port to the 416. The size now is 26 in. X 3 1/4 in. or 84.5 cu in. This does help the bass, but you really have to crank them up. I also have boosted the bass on my amp by about 4db. Someone also told me the cabs are actually too large volume wise for good musical sound reproduction. (I hope not)

I have heard that "bracing" the cabs also helps the bass although I have not seen any detailed description or pictures. I have also used Redux acoustic insulation in pretty much the same manner as the original Altec design. Could more insulation help? I don't know.

The 511 on my cabs was mounted inside. I moved it back to the top. I used steel angled stock with the holes in it I got at Lowes for mounting. The holes line up perfectly with the bolt holes in the 511. I also used rubber grommets, also from Lowes to mount the 511 to the angel stock. Rubber washers were used between the 902 and the rear stand off bracket. this makes the 511/ 902 assembly completely rubber mounted. I have detected NO ring. Striking the horn only gives a dull thud.

As the others have noted, I am not satisfied that my A7's sound as good as they could. I will pay close attention to your progress. Please don't leave anything out.
Thanks and good luck.
Marvin

[mah]

Ping AB.

The pics in Pano's OP, above, do not show on my computer screen. Other members can see them. Is there an ex-USA block involved somewhere or is there a Hostboard setting that I need to enable?


Cheers, Marshall.

PS. Also, generally, links shown are very similar in appearance to normal content text, making it easy to miss them. Do others have this problem?

[GM]

Pics? I didn't see any in this thread just now.

Me too; it's always been bad for me and now I can see no difference, so started using different colors and/or BOLD text to highlight them.

GM