My A7-500s. A journey

**Panomaniac** · November 19th, 2009, 06:21 PM

Starting here a running account of my "new" Altec A7-500s
I'll document my findings and the work I do one them. I've been wanting a pair of A7 or A5 speakers for many year, now thank to forum member "old Guy", I have a pair. And at a very reasonable price, too!

These belonged to a fellow who ran a music store in Ohio.

Here's what I got (see photos below).

825 cabinets (I think) in 3/4" ply. Looks like A/C grade, lots of knot holes on the inside. But pretty solid and in nice shape. They have been taken care off.

416-8A drivers in the 16" frame. Don't know if they have been reconed. It looks like the cabs had 15" woofer originally, as the bolt circle is so small that it just barely fits the 16" cast frames. There is window screen in front of the 416s, as you can see in the photo. Don't know if it's to keep bugs out or beer bottles!

On top of the cabs, bolted on, are the horn houses. More 3/4" ply with a 511 horn + 802-8 ohm driver. The 802s have the symbiotic diagrams and loading caps. They appear to be from 1971. I've never seen the horn house before, Todd W says they may be from the 50s.

Crossovers are the stock N-501-8A type. Nominal 500Hz, 2-way with L-Pad on the HF side. I will post schematics and photos later.

OG said that one of the compressions drivers was bad, but it turned out to be an easy fix. The spade terminals were touching the inside of the back cover causing a short. Bent them down and it works!

So I have a fully working pair of A7-500s. Yeah!

**Panomaniac** · November 19th, 2009, 06:41 PM

Part two, the sound.
Well of course I fired them up to hear the glorious "Voice of the Theater" sound.
And how do they sound? Well, they work....
To be honest, I do not like the sound. No bass, very midrange heavy, a bit muffled. I can see why a lot of folks don't like these old girls. Maybe great for dialog behind a movie screen, but not great for music. I've heard a horn + 15" sound much better. Much.

I spent a few hours carefully measuring, listening to and adjusting the the horn level to get it set right. Better, but not great.

At the moment I am running 1 A7 on the right and one of my "Big Ugly Speakers" on the left. The do sound different. The A7 sounds midrange heavy and closed in compared to the B.U.S.* I am mixing all signals to mono and going back and forth between the 2.
The big 803 multicell horn sounds so much more open and live than the 511. Voices seem to come from the area of the speaker, but can't be pinned down to the speaker. The A7 on the other hand, is definitely "speaker" sounding. The horn is there, no mistake.

I did a lot of EQ work (DEQ-2496) to get each as flat as possible. They still sound different. The BUS is bigger and more open, the A7 closed and midrange heavy. But the 803 seems to have a slightly annoying edge that the 511 does not. The 511 may sound like a horn, but it is not fatiguing or edgy.

*Altec 604-8K in a 14 cubic foot box topped with an Altec 803 horn driven by a 291 1.4" driver (Symbiotic fram). Passive crossover of my design crossing at about 450Hz, 2nd order.

Next - crossovers.

**Leland** · November 19th, 2009, 08:25 PM

Thanks and good work. I will be following your thread closely, as I too am a recent A7 Voice of the Theater owner. I too agree that it doesn't have much bass and sounds muffled.

Compared to my Klipsch La Scala....the La Scala blows the A7 away in bass and clarity of sound.

But if I drag the A7 out of the garage and crank up the volume....watch out...geeze...it has absolutely stunning sound and clarity at higher volume.

Which leads me to believe....they might not be suitable for in home use.

**Panomaniac** · November 19th, 2009, 09:46 PM

Hey Leland. Yep, that sounds about right. Just got off the phone with my friend John who had the Klipsch when he was in high school. His buddy had the A7-500. Johns says his buddy coveted the bass of the Klipsch, while John coveted the smooth detail of the A7.

There are some things to try.

Put them against the wall. This should help with bass. Maybe add wings
Change out the symbiotic frams for all aluminum. May reduce the horn sound. Should be better overall. I'll try my 806 drivers.
Damp the horn. The 511 does ring (my 811s ring much less). Damping the horn should also kill a lot of the "horn sound."

My goals:

I hope to bring these old girls up to date. I know they can sound better with proper care.
Damping, tuning, crossover work, etc.
The reason I know they can sound better is because my favorite speakers ever are the pair of A5s that I helped rebuild in Paris 22 years ago. They are the only speaker I've heard that had NO speaker sound, none. Others I've heard were close, but none disappeared the way those did. Even with different amps - everything from 300B SET to Halfer, to Krell, vintage Scott, Dynaco or MacIntosh - all the way to a Luxman integrated. All sounded great on these speakers. Different, more or less colored, but great. No speaker has ever sounded more "real" to me. Like real people playing music on real instruments in a real space. Changing the electronics was simply like putting on a different pair of sunglasses looking at the rand Canyon. A different tint, but still obviously the real thing. Beautiful.

That's were I hope to go with this pair.

**Leland** · November 19th, 2009, 10:00 PM

Panomaniac, Thanks.

Yes, I have done nothing to work on the sound or modify the Altec. Mine has a 515-16G and an old 288B Driver with an 805 horn. N-500-C Crossover. It is old school, perhaps late 1940's except for the Woofer. Don't get me wrong...I love it....but just not as refined as the La Scala for my uses.

I know so little about the Altec....it could be an A5 and not an A7.....

I've played around with the antenuator on the crossover...that is about it.

THe Altec is a true Professional Audio unit....for pro audio applications. At "Volume" it is stunning.

By the way,,,Yours look GREAT...congrats on the new speakers. Do you have a pic of the 803 horns?

**scharron** · November 19th, 2009, 10:10 PM

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** · November 19th, 2009, 11:41 PM

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** · November 20th, 2009, 01:47 AM

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

**Panomaniac** · November 20th, 2009, 01:56 AM

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.