Doubling up Altec speakers, I have ?'s

[jeenie67]

Hi, I'm contemplating building cabinets to house two 12" Altec woofers each (combining my model 14's and 15's) and putting both horn drivers between them. I have to build cabinets anyway because the 15's were damaged by water; the drivers surviving unscathed. The 14's are mint, but I can store them. I'd like to use the 15's x-over and cast some horn bodies. Would anyone have some information...will the x-overs design parameters be affected by this? Would it be alright to wire them at 16 ohms or stay at 8? I'd like a fuller sound..just move more air. I'm learning quite a bit on this site and really appreciate all replies.

[toddalin]

Wouldn't it be easier/cheaper to just purchase something like this? Hard to go wrong at $300/pr. No affiliation and yeah I know, Kalifornia sucks!



http://losangeles.craigslist.org/lgb/msg/957688907.html

[jeenie67]

Howdy Doody....Well I work at a technical college and have access to almost anything I desire...so 14 ply Baltic Birch plywood for starters (1") with a 1/4" ply of MDF on the insides and 1/8" on the outsides for the chestnut laminate. I want to keep the same basic design, but horn load the reflex port. I need something to do while classes are running (I'm in the labs just observing the students do their projects) instead of standing around making them nervous. I've noticed by just changing a horn driver the differences it makes with the x-over. I had one model 14 Manta Ray (MR) horn original and a 808-8A driver bolted to the other MR; I had to double the volume of that side to balance with the other. Now I took the diaphram out and put it in the other MR and things are balanced. I intend to run one horn per side (I have two MR's and two 808-8A's) and all four 12" woofers.

[hmolwitz]

You would really be engineering a speaker from scratch which is a fair piece of work even for some of the experts here, certainly you could hack something together and it would move more air than what you have, but I assume that you want to put something together that is also good sounding.
Those are both excellent well engineered speakers, if you just want to move more air, get a big subwoofer and cross it @80. You will get substantial output from the speakers you have at that frequency.
The project you envision isn't necessarily doomed from the start, but would require extensive effort to wind up with an improvement.
Harry
Read here on the 9844 which is similar to what you envisioned.

[jeenie67]

Hi, Highly informative! I appreciate your input highly! And the link. If I had good cabinets I'd go rear speakers maybe off my OPPO disc player. Coming direct from the OPPO into an Aphex interface to the Crowns is pretty damn good sounding (with sacds etc.) I'm thinking more of my vinyl, that's the tough one. I have a Conrad Johnson with mods to the caps etc. set aside for a TT. I have all January to think about this till I resume classes. The bottom line though is my ear, what I hear. It's really hard here in Buffalo to find any high-end systems for ear evaluation. I know what I want to hear and don't want to spend a lifetime trying to acheive it. And with low bucks...college at 54 years is tough on the pocketbook. Glad I have the other college for any materials. Again, thank you. Jeenie67

[jeenie67]

This is the good cabinet (I could use as a template). It won't stand up to any internal pressure, the joints are splitting. Right now my "$10 garage sale find" Columbia phonograph is keeping the cones and coils exercised. Pretty decent little package of vintage musica. The power amp uses three 6L6's and the mono preamp runs a sole 12ax7. It has a terminal for an extension speaker and a jack for a tuner (that's a Meissner tube FM tuner on the radiator (shut down!). For about a $30 investment, it doesn't sound bad. On when I'm giga-boxing. Going back to read that link again, Thanks!

[hmolwitz]

Check With Bill at Great Plains Audio and see if they have the horns for you, they do have some horns available reasonable, if not keep an eye on Ebay, they do come up and not always mucho$$$. You could DIY a horn as well, but the same caveats apply...And you would need to redesign the crossover as well.
You could also post here in the Marketplace, someone may have a stray.
Pair sold here for 75$ http://cgi.ebay.com/Altec-Model-15-H...3A1|240%3A1318

Tod Whites Altec users group is a good spot as well, but the site appears down.

Harry

[Zilch]

What you propose would be well characterized as "A bad design."

Much as we'd like to believe otherwise, there is far more to building loudspeakers than sticking drivers and horns in (or on) a box.

There are two basic approaches:

1) Study up the fundamentals and what makes existing designs successful, OR,

2) Build whatever you like, and then figure out why it sucks, once you recognize and acknowledge that it does....

Pop quiz:

A) Why would M15s suck?

B) What's "special" about M14's MantaRay horn?

C) What is there important to know about 808-8A?

D) What's wrong with running multiple woofers in parallel over a wide bandwidth?

[jeenie67]

Hola, Thanks for the input. I have scanned the Altec pages on the various speakers such as the 9813,9820-8A, 9843, and some others just to see what other designs used the same drivers and horns etc. as mine. I have only two criteria to meet. One, replace the 15's wasted cabinets with something and two, try to keep the footprint of these speakers to an acceptable limit. That's the one consideration in my idea of combining them. In answer to your POP Quiz: A. the 15's do not suck, I have no usable cabinets for the components. B. The only thing special that I can see in the MR horn is the dispersion pattern and the difference in the magnet structure. C. about the 808-8a's, they're really heavy! D. I have no idea of the problems or anything else associated with running multiple woofers in parallel. That's why I come to this forum, to learn from more knowledgeable individuals. One idea I had is to copy the 14's cabinet for the other 15's drivers and stack them, top inverted (horn on the bottom). I used to have Advents done this way a long time ago. Any input on this? Hey! Happy New Year !

[speakerdave]

What exactly is your question at this point?

[Skywave-Rider]

I'd consider reconstructing new 15 boxes, if you like those, because it's a known design and you have the components (I think.)

Careful, mentioning stacking may be hazardous on some forums.

One thing about the 808s Zilch was referring to is their lack of HF extension.

If you go with a single woofer system, you don't have to worry about phase cancellation in the upper woofer frequencies when listening at certain horizontal angles in a side by side system, or vertical angles in a stacked dual system. (IIRC from my own 9844-8B thread.)

I eliminated that problem, among others, by making a simple mod; running the dual woofer system in 2.5 mode.

But since you don't have 2 identical pairs of woofers (you don't, or do you?) why not go with a single woofer 2way?

Just thoughts from somebody who made a few mistakes on a vintage Altec system.

Hola, Thanks for the input. I have scanned the Altec pages on the various speakers such as the 9813,9820-8A, 9843, and some others just to see what other designs used the same drivers and horns etc. as mine. I have only two criteria to meet. One, replace the 15's wasted cabinets with something and two, try to keep the footprint of these speakers to an acceptable limit. That's the one consideration in my idea of combining them. In answer to your POP Quiz: A. the 15's do not suck, I have no usable cabinets for the components. B. The only thing special that I can see in the MR horn is the dispersion pattern and the difference in the magnet structure. C. about the 808-8a's, they're really heavy! D. I have no idea of the problems or anything else associated with running multiple woofers in parallel. That's why I come to this forum, to learn from more knowledgeable individuals. One idea I had is to copy the 14's cabinet for the other 15's drivers and stack them, top inverted (horn on the bottom). I used to have Advents done this way a long time ago. Any input on this? Hey! Happy New Year !

[jeenie67]

Hi, I have 4 identical woofers, even similar part #'s. I presume there is some kind of code or sequence like some other #'s, eg. first 3 digits classify a spec, the next 4 specify maybe something else etc etc. I like the MR horns sound over the 808's. That's why I was thinking of just using them between 2 vertical woofers. I'm searching for ideas and like I stated before, building new cabinets is not a big deal, I need something to do during the students lab time. I'm open to all suggestions. The 808's from the 15's do not have the horns. I was given the 15's free from a computer lab tutor; he was the original owner and started to part them out before I discovered he had them ( I've built some bookcases for him free and we started talking tunes). A question I have now would be in mounting the woofers, better side by side or on top of each other? And horn placement, between the woofers or on top as original. Their placement is 6 or 7 feet apart slightly angled up and in ( the 14's sit on Marlin 444 rifle cartridges; cheap effective spikes). I also have two diffferent sets of x-overs, the 14's and 15's.

[Skywave-Rider]

Well, it's a ground up design you propose, and that's fairly complicated, at least for me. (Unless you can find a similar Altec product that had these components. I don't recall one.) I'm working on my first ground up, which will be straightforward, so perhaps others will have some ideas to help you distill it down a bit.

I think vertically stacked woofers make more sense in a home environment. Horizontally stacked systems, like my 9844-8Bs, are usually designed as studio control room monitors which in most cases fit better when a console is in the way, or the boxes are hung in the wall/ceiling junction.

Next I assume you'll want to find out how the 2 woofers will perform wired together and in what size/type of box.

Then you've got to design a crossover. You might get lucky with one of your existing crossovers, but it seems unlikely.

I know, now I'm really not helping. LOL.

[Zilch]

I like the MR horns sound over the 808's.

What drivers are on the M14 MantaRays?

[Skywave-Rider]

http://www.lansingheritage.org/html/...s/model-14.htm
I see "tangerine," nothing more yet.
EDIT: Zilch you probably found specs by now, but since both the 14 and the 9842 list FR up to 20kHz, wouldn't that be 902?