A7 VOTT Newbie Help

**ClassicComics** · July 24th, 2008, 07:47 PM

Ok, as most of you know I have owned a pair of Altec A7's for a long time as well as having them powered by Altec 1590B amps, however the system was originally put together for me by a friend. I love this set-up and as many of you know I am currently seeking another A7 for a center speaker for my theater.

The sad part is I never bothered to learn that much about them. In the search for a matching center speaker I have ended up learning a lot (mostly through this forum), but have TONS still to learn.

Since my theater is currently being rebuilt by me, my A7's got piled into my pool table room along with everything else. Well, today I unburied one of them and opened up the back and also pulled out the horn so I could find out for sure what I had, and become more familiar with it.

So I have a 421a bass woofer, a 511B horn with an 807-8a driver and a N809-8a Dividing Network.

What I also discovered is that there is no foam or padding or insulation or whatever in my cabinets and from what I have read there should be. How do I figure out what and how much and wear to put this?

Lastly, I am sure this question will show how truly uninformed I am on this, but I can't learn without asking... so I am trying to get all of my ignorant questions into one post..... on the dividing network there is a knob for the attenuation setting from 0 to 10. I think I have always had these set in the middle at 5, but I really have no idea how to set them, or honestly have a solid handle on what this does. I think it just adjusts the resisitance and allows me to lower the load from the amp to the speaker to make it less loud, but I don't know that I have a solid handle on this and how it would work in my application as far as best sound quality.

So there is it... help me learn. Through this forum I have gotten much more into the Altec vintage stuff, and it is starting to become a bit of an obsession. I have always had friends that were really into vintage stuff, mostly building tube amps etc... but now I am getting into it (although I am sticking with solid state) and I am trying to figure out where else I can use more Altec gear and what I need. forums

THANKS!!

[ July 24, 2008 04:52 PM: Message edited by: ClassicComics ]

**bfish** · July 24th, 2008, 08:28 PM

Hi CC,

Start here;

http://home.earthlink.net/~jmarkwart...es/spaltec.pdf

Your drivers are the "roadie" models, intended for PA/SR/live bands. Higher-Fi can be had if you want it.

2" of fibergalss batting, usually on the back, and at least one side. Season to taste.

The XO control attenuates just the (511) horn, so you can balance it to the LF.

There's a ton of old threads here with more, but the linked article covers the bulk of it in one shot.

**ClassicComics** · July 24th, 2008, 10:51 PM

Thanks - I'm reading through it. A lot to take in. I think I'll have to go through it several times. So far it looks like he doesn't say anything about the 421a woofers, what's your thought's on them? Do I need to replace with something else?

Also, what drivers would you personally recommend for the 511 horns? I don't think I am interested in switching to a different horn right now... and it sounds like I should stick with a 1" driver, correct?

Thanks!

[ July 24, 2008 08:15 PM: Message edited by: ClassicComics ]

**Carl Bill** · July 25th, 2008, 12:42 AM

Hey!

My .02...

I would think you would do better with 416-8B LF drivers and 802-8G HF drivers. The 421's are more for PA sound reinforcement and musical instrument than sound playback - or home theatre.

Also, how far away from the cabinets will the listening area be? I think if you are more of a near field listener, you would do better with Model 19's rather than the horn loaded A7 (828's I assume) cabinets.

Lot's of things to consider.

I am planning on Model 19 variants for my situation. I love my 19's much better than my A7's (so many variables here to discuss) in the house for sound. The horn loaded A7's "project" the sound much farther than my listening area, so they are better suited for larger rooms or outside venues. Horns loaded bass is very nice and I really like it in my 828's in the right situation. But in the house, the Model 19's rule. I know there are Altec Coaxial's that will do similar duty in the home, so you have options. I just fell in love with the 19's in my employment with Altec in 1980.

Hope this gives you any ideas. forums

**Steve Mac** · July 25th, 2008, 02:21 AM

Originally posted by ClassicComics:
...
Also, what drivers would you personally recommend for the 511 horns? I don't think I am interested in switching to a different horn right now... and it sounds like I should stick with a 1" driver, correct?

Thanks!

[ July 24, 2008 08:15 PM: Message edited by: ClassicComics ]

Carl's pretty spot on with this:
416-8B LF drivers and 802-8G HF drivers
The 421's you have will take a licking and keep on ticking. They are not bad sounding at all.

The drivers I have are 808-a's...alnico but no tangerine phase plug. After I followed the mods here on this forum for these drivers...they are...sweet! I think I've been playing with ~3dB of EQ above 10kHz...

The problem with drivers and passive crossovers is that you must find a system. In other words...the crossover, the bass and midrange horns and drivers must match. As I've been tweaking my big rig, I stepped around the problem by getting a digital crossover. One of these puppies will allow you to set time delay, XO slopes, XO points, gain, limiting and EQ. Some of the old timers here will say that's cheating. forums

They're right! forums

But you will dial your system in quickly and the issue of driver mismatch is mitigated. Some driver combinations will never work well together or in the cabinet or horn they are placed.

But Carl's recommendation will work and work well.

If you like the sound of this system right now...even though it may be improved...you may just leave them as is...and tweak as you learn more and feel confident with phasing in the changes.

Oh, and with the horn you have you are limited to the 1" driver types. I've got a pair of 511E horns that will accept the larger format compression drivers. I've yet to use these just yet. Just trying to get other things right at this point. I've got a big room...bigger than yours and believe me, yer not even opening up yer system in that room...in effect you got PLENTY of oommph.

But with larger drivers...you will have about as high efficiency as high efficiency gets which means yer amp had better sound good at a half a watt. IMHO, and in general, the less the driver has to move to make sound the faster and cleaner it gets.

**Steve Mac** · July 25th, 2008, 02:30 AM

So I have a 421a bass woofer, a 511B horn with an 807-8a driver and a N809-8a Dividing Network
I'm guessing/assuming that 807-8a can load down to 500hz. I honestly don't know. If it does...and it's just my personal opinion...but I've played for hours with XO points and I've been listening to a XO point of 565Hz...shoot...I should know this...I think 12dB slopes...this is what I like. Some say 700-800...but it clears up for me better at this lower point.

**RonSSS** · July 25th, 2008, 06:22 AM

For HT. I would reccomend 416 woofs. Either -8A or -8B It's going to depend on whether the 421 frames are 15" or 16". Even a -8C would be better.
For HF, I'd look for 902-8A. Sound even better than 802-8G to my ears, and a ton cheaper.
Damp the horns.....sand and latex paint, bondo, or even the expensive stick on stuff.
X-over.....find some model 19 or 1201-8A....same thing, you can tailor the mids vs. hf. Wonderfull on A7's. Altec used these on the late A7X speakers....which featured 416-8B and the 802-8G hf drivers. I bought a pair new in 1977......

You never know what you have till you take em apart.....

I wonder if the 421's have the same motor as the 416....they could be reconed.

Your hf drivers could get new frams and become 806's. If they are stock, they have the symbiotic frams as mentioned, and won't go real high. Tangerine is better.

Ron

**notloudenough** · July 25th, 2008, 03:01 PM

cc,
You either have a set of 1208's or 1236's depending on the date of manufactoring. Or, a ******* version of the above, since you said that your friend put them together for you. You'll have to tear into them a little more to find out what exactly you have.
1. What diaphragms do you have in your drivers?
Are they original symbiotics (with the orange surround) or are they all metal ?
2. Are the accoustical loading caps in place ?
You may or may not want these depending on your listening preference. You'll be able to tell when you take the back covers off, can you see the metal dome of the fram or is there a black cover over it ?
3. Running the volume pot at 5 or 6 doubled the power handling of the system from 50 to 100 watts pink noise.
4. If you've had these for awhile I'd recommend turning your 421's 180 degree's in the cabinet to avoid cone sag. The 416 and 515 are more succeptable to this than the 421 but it's good practice anyways. Keeps the coil from rubbing and leading to failier.
I have two 1208's and a ******* for my center. And i love them. I replaced the symbiotics with all metal frams but kept the loading caps. I kept busting the frams in my 605's 'till I put the caps on and carried the practice over with my 808's. I have three 421's across the front and two more for side surround, and my 605's for rear surround. Not only do I use this set up for loud music but also for my HT . Depending on how and what your going to listen to will depend on what you'll want to change or not. The 421's will handle power and produce good bass.