My A7-500s. A journey

[scharron]

Hi Guys,
I own a pair of Magnificents for my two way stereo, and have a pair of A-7s in my home theater with the equivalent of a 9844 for my center channel, JBL surrounds. [ I know, but they came out of a theater in Oklahoma]. After having lived with these speakers for at least 25 years, the one thing I have found is that they sound a lot better when they are EQ'd, anything but flat. I boost low bass up to about 100 Hz and then start a gentle climb on my EQ from about 1000 Hz up. Not a lot but, but just a gentle climb. Augment the Maggies with a def tech supercube one, and the HT with a supercube reference. I mix sound on a regular basis and I can almost guarantee all the live sound you hear anywhere has been EQ'd for the venue. I do it for my boards and I do it to the great big speakers with the mildly ugly horns that we all know and love as this company named Altec. And I might add, that anyone that listens to these giants of audio in my house, and HT all say that they sound amazing.
It thrills me to this day that I have not grown tired of their sound. Can't say that about the multitudes of speakers that they replaced.
side note: was at a festival relatively recently that had an old school sound guy running four 825 cabs with larger horns on top fed by 288's. there was a great big "honking" ugliness to the midrange. I got to talking to him for a while about his speakers and how he EQ'd and he said there set the way his RTA said to set them. I gently suggested he listen to the mids and he started pulling them down. all of a sudden he started smiling and said I knew my ears were telling me something just wasn't right but I couldn't find the problem. problem was solved when he just listened for a little bit. the sound got much much better. and the old altecs sounded a lot better than the shrill stuff guys are using now, although
the altecs are always a lot bigger!!!
just my .02, but anything but flat!
regards,
scott in nc

[Altec Best]

Hi Mike, They look Fantastic though it's a shame about the sound but I have no doubt once you get the acoustics right on the room,tuning,crossovers,etc... you will have that smile on your face that all Altec owners will have once project complete.Once you get your Altec's set right that smile on your face will be PRICELESS !!! Kinda like this guy right here to the right > You are doing a great job on the evaluations and providing great info for everyone Thanks !!!

[RonSSS]

Try the later N1201 crossovers. Or the model 19's. Way better than the originals.
Remove the screens over the woofs.
416-8B's are better woofs. The -8a are a bit wooly.
Use 802-8G or 902-8a drivers with the bug screens removed.
Do damp the horns.
Brace the cabs per Jim Dickensons article.
They will come around.
BTW, EQ the low end only, a 1/3 octave EQ below 500hz will work wonders.
I actualy added 1/4" plywood spacer rings at the woofer mount to keep the cone from hitting the cab on big excursions.

Remember, these are theatre speakers, not home. But with work and patience, they can be quite nice.

There is a reason M19's were better for home use.

ron

[Altec Best]

Remember, these are theatre speakers, not home. But with work and patience, they can be quite nice.

There is a reason M19's were better for home use.

Hey Mike, I think Ron brought up a good point. These were designed for large areas not a small room inside a home.So it will take some tweaking to get them right but you do good work very thorough.I thought your port was too big also for the 416 I would even try reducing it even more to what the M19 uses a 2 1/2" x 11" port you can always enlarge it.Also the 802 symbiotik with loading caps, most people I have talked to don't like the loading caps so they remove them and stick in a thick piece of felt in the end cap instead.And the symbiotiks are more or less for power handling replace with a all aluminum diaghram. Well anyway nice job Mike you are no novice we all can learn more each day for sure.I learn something new every time I come to this forum isn't it great !!! Those A-7's look to be very nice shape though. Regards

[Panomaniac]

Thanks guys, lot's of good feedback. I didn't know this thread would get so much interest. Yep, a get a nice set, thanks to O.G.

Some more playing this afternoon. Just FWIW.

• Putting the A7s in the corner or right against the back wall helps the bass a lot. Certainly seems to be the way to go in a room like mine.
• Adding a wing to one side also helps the bass. The A5s I used had wings in both sides.
• Rolling the crossover point up and down from 450Hz to 1.8KHz does not change the sound nearly as much as I thought it would. The 511 seems to blend well with the woofer all thru this range. Above that and the mids start to drop away (woofer roll-off) and below that the low mids go away (horn roll-off). Things do change, but it's fairly subtle. Good drivers, I suppose!
• Pulling out some mid with EQ does help the horn shout. A dip of about 3-4dB centered at 1.5K is a good starting point. Overall or just on the horn.
• Vibration. The woofer horn vibrates like crazy. It's the worse part of the cabinet. And it's pointed right at you. Mine are not kerf cut in the back, but are a solid bent piece. Damping material and some bracing back there ought to work wonders.

I agree about the symbiotic frams and the loading caps. They can't be helping. Will swap in an 806 driver tomorrow for a listen. That may smooth things out a lot.
OK, back to the music (Carlos Santana).

Note, just a quick swap to a 811/806 made a BIG difference. So much smoother, better balanced and more top end. Gives the 803/291 a run for its money. Eager to hear what the 806 does on the 511.

[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