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://images.craigslist.org/11c1fd1263k23m03o38ce04c3de9a83821e11.jpg

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 (http://audioheritage.org/vbulletin/showthread.php?t=18913)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-Horns_W0QQitemZ260332915750QQcmdZViewItemQQptZVint age_Electronics_R2?hash=item260332915750&_trksid=p3286.c0.m14&_trkparms=66%3A2|65%3A7|39%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.... :yes:

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/altec/specs/home-speakers/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?

[speakerdave]

Here are the issues I see, if I've understood what you have and what you are proposing:

1) The four woofers: I believe those woofers are designed for linear response in those speaker systems. Used in pairs acoustic coupling between the woofers in one cabinet could very well complicate things because it would create a big hump in response at frequencies that are already often exaggerated by placement in the room.

2) Crossovers: If you rebuild with one woofer per side you must use the crossovers that go with the horns you have, and you must use the drivers that go with that horn and crossover. Neither of the crossovers will work correctly as-is with two woofers on each side. The low-pass sections would have to be modified; you are not competent to do that, and nobody can do it for you at a distance.

3) Compression drivers: the 808-8A is a good driver, but for hi fi you would want to fit it with the diaphragm made for the 802. The 808-8A/802D and 808-8B/802G drivers are otherwise the same. The Altec lit seems to be saying the drivers have a tangerine phase plug, but the 808-8A does not (the 808-8B does). So, there may be things in these speakers that are not original. I can't figure out what your other drivers are, or even, for sure, whether there are other ones, or whether you have drivers, crossovers and horns that were all originally part of one system.

4) MTM's: Configuring a speaker with a treble framed above and below by lower frequency drivers is actually quite complicated. It involves, first of all, aligning the acoustic centers of all the drivers, and the distance between the cone centers of the LF drivers and the diaphragm center of the HF driver should be no greater than one wavelength at the crossover frequency. Failing that, then IMO you must use a larger horn and lower frequency and the distance between the two LF drivers must meet the same standard or better, preferably no more than one-half wavelength. Just by the nature of the physics and the dimensions of the horns and drivers that do the necessary things, this is difficult to achieve. Otherwise the purpose of the configuration, the seamless melding of the drivers, is not met, and negative complications result. If you play the LF drivers higher than the frequency for which one-half the wavelength is less than the distance between the axial centers of the two LF drivers, the two LF drivers will not work as one source, which is bad for a couple of reasons.

You have not said so, but I gather that you want to use just speaker elements you already have and you do not want to put ANY money into this project. Therefore, for this reason, and because of the apparent lack of knowledge about acoustics and electronics--i.e. speaker building--you should repair or rebuild the cabinets for the pair of speakers for which you have the crossovers, horns and all the drivers, and that's all you can do. Beyond that, your work, time, and effort, and your employer's materials, will not be rewarded by good sound.

If you want to get started in speaker building, making an enclosure for an already-engineered system and learning to tune the enclosure correctly is plenty enough to do the first time out.

Good luck!

POSTSCRIPT: By the way, a bit of advice. I cannot reply to your speaker project without adding this. Your intimation that you are helping yourself to materials that belong to your employer may not sit well with everyone, including, by the way, your employer, who, though he or she may tolerate a certain amount of it because he expects it is going to happen anyway, at bottom may well not like it very much. At this point in time, and if I understand your particular position as you have alluded to it, I would NEVER take anything from the job and use it for my own purposes. Employees have rights, but none of them is sufficient to undo the vulnerability you would create by taking something that belongs to your employer and appropriating it for your personal use.

[jeenie67]

Hi, The MR's driver is a bare magnet assembly with a small very hard plastic cap, padded on the inside, covering the coil, standard screws, 3, non magnetic. The assembly looks like a squared off flying saucer. The ring of the coil houses the terminals. There are no numbers anywhere. The horn is the standard black plastic 14. I don't like the 14's x-over, a printed circuit board. I just have something against PC boards. The 15's has coils and caps and nice stuff, but that x-o is particular to the 808-8a which the sound hurts my ears....what..r..ya goin to do! I would really like to make , learn for the first time, a x-o. I always will have the 14's in the closet; I need to play. I like the feedback on verticle woofs. I 've researched sites and Altec/JBL pages, been into power stereos all my life (since 1973) and have owned, years before, some basic equipment that has just done the job (during that era). I've played live music from hard rock (played a cut off Zepplins 2nd album at it's release at a high school dance which stunned everybody, nobody in those school bands at that time plugged into stacks of amps and Lelie speakers) to tube melting blues to Bob Wills cowboy stuff. I am a schooled musician and play piano, almost anything with strings, and percussion. I know what a 17" Zilg cymbal sounds like, a wooden Ludwig snare, and can tell with a high accuracy what guitar someones using on an album or disc;the timbre. I know when a violinist's rosin is wearing thin, I only have my ear and experience with real instruments to guide me, and all your technical intellegence.

[jeenie67]

Oh Yeah, for Speaker Dave...when I mentioned all the materials at my disposal...you should see the CAD fed CNC saws, CNC milling machines I can play with to produce small hardwood or alloy products. Not to mention mig/tig welders, metal forming breaks and shear presses if I want to make some lenses, hydralic tubing benders ( jeeze? ..how bout some strange looking port tubes!) every conceivable software for CAD...the list goes on and on and the Chair of both Departments I'm in, like what I'm doing, because I pass it on to others. Something learned in fabricating my stuff may apply to a course project or process. Materials such as woods etc. I buy through the college at mass bulk prices even though I might purchase one piece. Materials such as cutoffs etc. are paid for and end up in the dumpster semesters end if nobody takes interest. The piles of plywood, just because its been sawed is scrapped. And that list goes on and on......just to clarify. Oh yeah, I'm getting to know the people in electrical tech. a few wings down from me. So far I've been "gifted" with some resistors and caps for my vintage radios. And they offer to repair parts on PC boards like the 1/4" jacks that always break. Jeenie...Thanks for YOUR input; almost have to print your reply!

[hjames]

The best approach is to forget the dual woofers and build dupe cabinets of what your original parts were used in.
That's the best design, its a proven design, and its a known quantity.

Its really not a matter of having really good machine tools at your disposal, its a matter of design, and everyone is very nicely trying to tell you you're pretty much on your own with this. Dual woofer designs are NOT easy to design - if thats what you really want, have at it ...

If you want to take this in reasonable stages, look into building modular boxes for each driver. Find a cabinet design for just one woofer and build that. Your woofers are a bit different, build the best cabinet for each. the horn can just sit in a basic cabinet that allows stacking. Build external crossover networks as needed.
Redesign and expand as required.

With separate cabinets for each driver, you have maximum flexibility for each and can shuffle parts as you like ...

If you like how the result sounds, you're home free. If you don't like it, try other approaches


Oh Yeah, for Speaker Dave...when I mentioned all the materials at my disposal...you should see the CAD fed CNC saws, CNC milling machines I can play with to produce small hardwood or alloy products. Not to mention mig/tig welders, metal forming breaks and shear presses if I want to make some lenses, hydraulic tubing benders ( jeeze? ..how bout some strange looking port tubes!) every conceivable software for CAD...the list goes on and on and the Chair of both Departments I'm in, like what I'm doing, because I pass it on to others. Something learned in fabricating my stuff may apply to a course project or process. Materials such as woods etc. I buy through the college at mass bulk prices even though I might purchase one piece. Materials such as cutoffs etc. are paid for and end up in the dumpster semesters end if nobody takes interest. The piles of plywood, just because its been sawed is scrapped. And that list goes on and on......just to clarify. Oh yeah, I'm getting to know the people in electrical tech. a few wings down from me. So far I've been "gifted" with some resistors and caps for my vintage radios. And they offer to repair parts on PC boards like the 1/4" jacks that always break. Jeenie...Thanks for YOUR input; almost have to print your reply!

[Zilch]

What Dave said.

Build boxes for your "spare" woofers the same width and depth as the M14s, and height as required for the optimum tuning of those woofers for use as subs. Invert the M14s on top of them and biamp the new subs. There's also a way to connect them passively to augment the M14 bass response.

I'll try to get you some advice about what to do with the 808-8As and M15 crossovers. I assume you don't have the M15 horns. I consider this a good thing. My only experience with M15s is supplying 2370A horns to replace the Altec goosenecks.

Footnote: Your bias against the PC board M14 crossovers is, uhmmm, ill-founded. It's unlikely that your elec tech pals could do anything better than to rebuild the same circuit point-to-point using new components. Just as speakers aren't merely drivers in a box, so are crossovers not just components wired together. They integrate the drivers, horn, and cabinets into a coherent system according to complex design principles and empirical determinations.

[speakerdave]

Oh Yeah, for Speaker Dave...when I mentioned all the materials at my disposal...you should see the CAD fed CNC saws, CNC milling machines I can play with to produce small hardwood or alloy products. Not to mention mig/tig welders, metal forming breaks and shear presses if I want to make some lenses, hydralic tubing benders ( jeeze? ..how bout some strange looking port tubes!) every conceivable software for CAD...the list goes on and on and the Chair of both Departments I'm in, like what I'm doing, because I pass it on to others. Something learned in fabricating my stuff may apply to a course project or process. Materials such as woods etc. I buy through the college at mass bulk prices even though I might purchase one piece. Materials such as cutoffs etc. are paid for and end up in the dumpster semesters end if nobody takes interest. The piles of plywood, just because its been sawed is scrapped. And that list goes on and on......just to clarify. Oh yeah, I'm getting to know the people in electrical tech. a few wings down from me. So far I've been "gifted" with some resistors and caps for my vintage radios. And they offer to repair parts on PC boards like the 1/4" jacks that always break. Jeenie...Thanks for YOUR input; almost have to print your reply!

OK. I appreciate your response.

[Zilch]

Best I have been able to determine, M14 driver is 902, and M15 is 802.

You took a diaphragm out of what and put it in what?

[jeenie67]

Hi, I've received from all whom have responded, some excellent suggestions and paths of resolution. You've all made a very important point. Duplicate the original 15's cabinetry or model new cabinets after the 14's (To me everything seems, in audio, a give and take situation). I think that building two more M14 cabinets is the way to go. Now I have to figure out what to do with the extra HF drivers, they're all a little different. Also the 15's x-o (I like just because it looks like vintage tube stuff). The numbers on these HF's are: 27-03-033952, --30836- ?, 033952. XO: 391822. Woofer:33785. The WFR in the other cabinet has a similar number with the last digit or two different. The 14's numbers also follow suite. I wasn't going to pull 'em; gasket gooey on 'em. Both Zilch and hjames gave me some real good advice to follow up on. Four identical M14 cabinets increases the versitality of them as stated and keeps their footprint small (I can go rear channels later too). Gee, what about wiring up all four? I have two Crown Xls 202's bridged mono feeding the M14's. I've attatched pics of the drivers. Hey! Thank you!