Author Topic: Altec A7 Voice of the Theater  (Read 598 times)

AlexanderMartin

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Altec A7 Voice of the Theater
« on: September 10, 2016, 12:20:21 AM »
Since all the guys on the other audio forums gets all their fun with their speakers, let's have some fun ourselves.
So I went into depth on a post about a score I made on same magnepan speakers, didn't draw much attention but maybe it will when I actually get around to working on them. So I got something a bit more 'period correct' if you well, I present to you the Altec Lansing A7 VOTT, one of the most iconic loudspeakers of all time.
These speakers are not perfect, they are quite beat up and the horn arrangement is unusual, as the horns are actually inside of the bass port (if you can call it that.) the paint appears to be totally original, and I wasn't even expecting the extra horn. We'll be taking them apart, as these are actually now my Dad's 'end game' speakers that he'll be running with a SE 6BQ5 amplifier. So I'll report on the driver compliment and progress painting (we got some factory matched paint with it!)

picard

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Re: Altec A7 Voice of the Theater
« Reply #1 on: September 10, 2016, 06:45:39 PM »
From what I've seen those are some expensive speakers. Very nice

AlexanderMartin

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Re: Altec A7 Voice of the Theater
« Reply #2 on: September 11, 2016, 12:35:15 AM »
They're quite pricey, we got plans to make them VERY nice. Here's some more pics, we popped them open today.

picard

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Re: Altec A7 Voice of the Theater
« Reply #3 on: September 11, 2016, 08:20:16 AM »
Always a relief to find everything untouched and all original. I was nervous opening up my Altec's. I would hate to find some Walmart speakers in there.

AlexanderMartin

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Re: Altec A7 Voice of the Theater
« Reply #4 on: September 11, 2016, 12:18:30 PM »
We were able to identify most of it from the auction pictures. Too bad two of the horns are blown. We got a pretty small sum into these, so we can work with it.

AlexanderMartin

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Re: Altec A7 Voice of the Theater
« Reply #5 on: August 08, 2017, 10:10:51 PM »
I return! And with updates! The A7's after a long tedious journey of purchasing drivers, selling drivers, priming, painting, and setup, we now have the Altec A7's in business! I try not to leave threads hanging. My dad is very happy. Here's the comprehensive list for those curious:

#1 Used bondo to fill in all the cracks, scuffs, corner damage, holes, ect.
#2 Thoroughly lined the cabinet with fiberglass
#3 Recapped crossovers, and cleaned the potentiometers for the HF attenuation
#4 Sold the original 811 horns and 807 drivers and replaced with the 802-8G drivers and 511 throats
#5 Removed and cleaned the woofers, using a very mild cleaner on the surrounds to remove dirt and crud
#6 Fabricated a rear mount as the original was for the 811
#7 Made some new wire utilizing high quality 14g copper wire to replace the worn old wire
#8 Fabricated new ports for better bass performance to Great Plains Audio specifications

As it sits, it produces highly detailed, articulate sound. They have a very "large" sound and fill the room with music and do so with little effort on their part. Quick and dynamic is the easiest way to summarize their sound. When you play some old jazz through these, the detail and clarity is stunning. the slightly rolled off sound of early mono records blends perfectly well with the tinge of forwardness the horns have and equalize wonderfully. We will be augmenting their lack of sub 50hz frequency response with a JBL 4645B subwoofer. When properly configured we should get 22hz flat for proper movie theater-like bass performance.

We will be actively bi-amping these in the next post utilizing (ironically) a magnavox push-pull EL84 amplifier that some ebay gutter put up for sale, as well as an Adcom GFA2535 for the woofers and JBL. More progress to be made.

TC Chris

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Re: Altec A7 Voice of the Theater
« Reply #6 on: August 08, 2017, 11:16:37 PM »
Nice.  What are the surrounds on the woofers--paper?  Foam surrounds were one of the great frauds perpetrated on the buying public.  Paper-surround speakers from 80+ years ago still work fine.  Cloth surrounds on my KLH Model 17s work fine after 50 years.  But foam....   My ca. 1983 Genesis speakers lost their surrounds all at once just after I had hand surgery, so I paid for surround replacement--but with butyl rubber.

Chris Campbell

AlexanderMartin

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Re: Altec A7 Voice of the Theater
« Reply #7 on: August 09, 2017, 12:12:54 AM »
Foam surrounds are commonly seen among Acoustic Suspension loudspeakers and Bass Reflex. These are completely hornloaded, they utilize a cloth surround that uses a special doping compound to keep it soft and pliable.

TC Chris

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Re: Altec A7 Voice of the Theater
« Reply #8 on: August 09, 2017, 10:21:53 PM »
My KLH 17s, currently semi-retired, are waiting for future service.  They're acoustic suspension and cloth-surrounded.  I've read that the doping material evaporates or disintegrates, and there appear to be much discussion about what to use as a replacement.  Have you done that?  With what?  The goal is obviously something that works but without changing the speaker's characteristics like resonance.

Chris Campbell

Harbourmaster

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Re: Altec A7 Voice of the Theater
« Reply #9 on: August 10, 2017, 01:47:51 PM »
Nice work. The finished product seems closer to an A5 than an A7 to me.


and I had to chuckle just a bit at those monsters sitting in such a tiny room...
-- Aloha, Ken

No Console Left Behind!

AlexanderMartin

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Re: Altec A7 Voice of the Theater
« Reply #10 on: August 10, 2017, 04:44:01 PM »
My KLH 17s, currently semi-retired, are waiting for future service.  They're acoustic suspension and cloth-surrounded.  I've read that the doping material evaporates or disintegrates, and there appear to be much discussion about what to use as a replacement.  Have you done that?  With what?  The goal is obviously something that works but without changing the speaker's characteristics like resonance.

Chris Campbell
Well Acoustic Suspension utilizes air in the cabinet chamber as an actual spring on the driver, hence why the woofers in classic AS speakers are so loose. So having a compound seal the edge (and any crack that breaks the air seal, for that matter) is crucial in the proper operation of the speaker. So in my opinion, re sealing is quite necessary and if I ran KLH's as daily drivers I'd make sure the edge and the entire cabinet is sealed, as well as the driver mounts.

AlexanderMartin

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Re: Altec A7 Voice of the Theater
« Reply #11 on: August 10, 2017, 04:46:22 PM »
Nice work. The finished product seems closer to an A5 than an A7 to me.


and I had to chuckle just a bit at those monsters sitting in such a tiny room...
A5's utilize the 1005 multicellular horn if my memory serves me correct.

And yes, they aren't in a 20x25 room, but they still perform quite well. And they're not the biggest speakers i've played with :)

TC Chris

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Re: Altec A7 Voice of the Theater
« Reply #12 on: August 10, 2017, 06:01:37 PM »
My question was what kind of doping material you use on old cloth surrounds.  I've read that it deteriorates or disappears and needs to be supplemented.  There have been lots of approaches.  I was wondering what you have used.

Chris Campbell