How to cramp two pairs of GPA 515C into a small living room?

Hi:
First of all I like to apologize for my poor English, because I am from Asia. I need all the help I can get. Here is the story. I used to live in a big house with a large living room, so I was thinking of building my self an altec system. I bought two pairs of GPA 515C, a pair of GPA 288H and a pair of 311-90 altec horn from e-bay thinking that I was well prepared for this project. Unfortunately, I was in a job relocating before I can start my project, and after a few months of relocating, I ended up in a new city, living in a not so big apartment with a tiny living room (compared to my old living room). I have all my components shipped to my new place and now I do not know what to do with them. My question now is, should I drop everything that I have and start with something smaller such as GPA 604? Or can I find a way to cramp what I have into a existing living room and still have a descent sound? My current living room is about 4.8mx4.2xm. Any help is much appreciated. Thanks,

First of all, no need to apologize, as you English is quite good.
You didn't mention cabinets.
I would never tell anyone with the great component collection that you have to drop them, and start over. I once had two 817A cabinets, each with two 515LF's, and a 288G/511E mounted atop of each. Not much different than what you have. All of that in a 5.5M x 4.0M room. Also, not much different. While not nearly ideal, the sound was Altec clear & very good........for me, and all my neighbors. This was, however, not in an apartment. 210, or 211 cabinets would probably not be suitable, especially with other furnishings. It can be done with the right cabinets. If your occupation causes you to move again, it may be to a larger space. Keep them, imho.

Greets!

Build ~320 L net triangular corner cabs with the drivers side by side and shifted up to be as close to top as practical and mount the 311 on top. Typically you want the 311's horizontal center-line to be at seated ear height or a little higher.

Try them sealed and if the bass is too 'lean', then get back to us for some venting ideas, so design the cab to have a removable panel for adding a vent if need be. A ~ 7" high, full baffle width removable gasketed panel should be big enough.

GM

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Originally Posted by jasminphotography

Hi:
GPA 604?

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I don't think you would be happy with those in a nearfield situation. I know I'm not.

GM, what do you think about running them Isobaric using the stacked method. He doesn't need a whole lot in his small room and the cabinet size might be really attractive.

Well, I don't know if nesting a front vent driver up near another's motor will cause enough overheating to raise its Qts enough to put it out of sync with the front driver or worse, cause VC damage. Turned magnet to magnet takes up more space and worse, lowers the isobaric loading, so cab design theory will typically yield a smaller than optimum net Vb.

If vented, it will need to be 5-6x longer than for a single driver, further negating any box reduction, though for sure it will be considerably smaller than the ~320 L I propose.

Then there's the issue of the driver's outputs becoming increasingly out of phase with increasing frequency, so the back driver will need to be rolled off ~ an octave above Fb for wide BW use.

I guess if there's the time/inclination/$$$ to experiment it might be worthwhile, but in the scheme of things it seems better to me to just build the biggest sealed cab that can be tolerated and use a LRT ckt. to EQ it ~flat in-room if large corner loaded cabs aren't an option. The downside though is that if he's using flea power, then this may eat up too much efficiency.

GM

Hi:
Thanks for all the replies. I believe triangular cabinet is out of the question, GM. My living room does not have perfect corners to place triangular cabinets. To be honest, I really want to use the components that I acquired from Bill. So, the question will be cabinet selection. Can you folks recommend cabinet designs that can be used in a relatively small living room with double woofers and still sound descent? Thanks,

Greets!

You're welcome!

Ok, so? http://hifilit.com/hifilit/Altec/1959-l.jpg

Small room, large room, my suggestion remains valid. Another would be an MTM, so each 515 in ~160 L net spaced apart vertically just enough to slide the 311 in-between them or make a box for the 311 and stack them.

GM

Hi, please pardon my ignorance if my next question sounds stupid, GM. I am not familiar with the term 320 L triangular corner cab. Is it the same as 830A cabinet and/or laguna cabinet? Also, if I stack the 311 on top of the cabinet, wouldn't the horn be facing each other? And with my small living room, will I be able to create a wide enough sound stage? Thanks,

Greets!

L = liters, ergo the cab's net internal volume (Vb) = 320 liters after the driver's and any bracing, venting bulk is deducted from it.

Right, a cab that is 'V' shaped when looking down on it. What angle you choose is up to you, but most are ~90 degrees included or a little more to fit in a typical nominally 'square' room corner.

??? How could they unless you intentionally turn them to face each other. Do the ones in the link I posted face each other?

Regardless of cab shape, how you position them in-room depends on what sounds best to you, though typically with most compression horns, aiming the left speaker at the far right listening position and vice versa works well or at least is a good starting point for experimentation with them firing at the opposite corners being common in long, narrow rooms.

The main thing is to not have any early reflections in front of the listening position above the ~500-1 kHz BW (band-width) depending on what sounds best overall to you WRT depth/width of sound-stage and vocal clarity.

How should I know if your room/system will create what you consider a 'wide enough' sound-stage?

As a general rule though, compression horns will generate a much deeper/wider sound-stage than a typical cone/dome speaker due to horn 'throw' and much greater directivity control in our critical hearing BW, but again, if you're expecting any but the most lossy constructed small room to sound like a large hall or even a large piano bar, then you'll need one of those processors that can create synthetic Hall, Concert, etc. special effects.

GM

Hi:
I have been asking my friends for cabinet suggestions, and a few of my friends suggested that a pair of 817A or two pairs of 16A stacked in MTM configuration might do the trick. What do you think about these two types of cabinets? How will they perform in my living room? Thanks,

That room is tough as it is quite small 15.6 feet x 13.6 feet. I just built some cabs like the ones GM had suggested but mine are ported and are 20 cubic Ft.I should have them up and running very soon I hope ! :D It is a GM guided design.Triangular dual woofer ported corner cabs. ;) Here's some pics.IMO you may have to go higher instead of wider with those Dims to limit the floor space requirements.GM could he go vertical instead of horizontal with the woofers ? When Pano did some calculations on the differences, the side by side wasn't to big of a difference,better yes,but not by much.I think he did some polar response plots on the differences between the horizontal configuration and the vertical,they are posted in my thread somewhere (Crossover Design for New Project).They are colorized. I'm just wondering if he could go up in height to help with the small room size ?



http://www.hostboard.com/forums/hbmc...2011/04/28.jpg

http://www.hostboard.com/forums/hbmc...2010/11/35.jpg

http://www.hostboard.com/forums/hbmc...2010/11/41.jpg

Beautiful cabinets--and enough woofer for your room size, without question. Please let us know how you handle the crossover/eq.

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Originally Posted by David Yost

Beautiful cabinets--and enough woofer for your room size, without question. Please let us know how you handle the crossover/eq.

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I agree, those cabs look amazing. I have a feeling they'll register on the richter scale when it's time to fire them up! Some great builds lately on this board/nice collaborations with GM and others.....