wire 2 speakers in parallel

[tnc]

I have a pair of vintage 8 ohm full range speakers that sound really good on open baffle. Luckily, I just got another pair and thinking about adding these to the same baffle. What would this do to the sound other than making them more efficient. I know that wire 2 speakers in parallel will increase the efficiency level 3db more - but other than this I have no clue how would the sound change by adding this extra speaker in. I could cut a hole and add the speaker in but kind of reluctant to do this as I can not just undo the hole in the event of not liking the sound afterward.

[jim campbell]

i would think that cutting holes in something "vintage" would be a bad idea.try building a similar enclosure and test how it sounds.or if you really want to experiment design and build a new enclosure for both sets of drivers.at least then you can return the vintage unit to its original configuration if you dont like the results

[tnc]

well, the speakers are vintage but the baffle are homemade - i just dont want to waste a perfectly set of baffle. there are lot of sentimental value to its.

[Zilch]

Terrible.

A bad idea to have multiple sources playing the same program material in the same listening space. It's axiomatic: they interfere with each other with phase cancellations and reinforcements according to frequency (wavelength, actually) and the differential distances between the multiple sources and the listener, i.e., "Comb Filtering," or "Lobing." Think "Flanging."

Not a problem, really, tho, unless one cares about actually hearing the music as the professionals who made, recorded, mixed, and reproduced it intended....

[tnc]

Altec 9844 has 2 414 speakers wired in parallel and a 806/811 horn in each cabinet and they sound great..........though, it could be because 1 woofer is being used as bass driver by having a large inductor connecting to it...

[moldyoldy]

...full range speakers...

9844's a 2-way (and still not full range)

[Zilch]

... though, it could be because 1 woofer is being used as bass driver by having a large inductor connecting to it...

D'ya think?

A similar configuration is used in 4435, 4612, and many others, including JBL's TOTL flagship Everest II. The second woofer is a "helper," reinforcing the bass, in part via this very mechanism, and does not play even the full range of the main woofer.

Bass wavelengths are long. The differential has to be 1/2 wavelength for the primary cancellation to occur. You can put money on it happening, tho....

[coherent_guy]

So how do speakers of the so called "D'Appolito" style, with a HF driver between two identical mid-bass drivers, one above and below it, fit or not fit into the idea you have presented?

I'm not saying you are wrong because I don't know either way, but the D'Appolito configuration came to mind so I'm tossing it into the mix. I believe the D'Appolito configuration is supposed to reduce or eliminate the negative effects such as lobing that you mentioned. :dont-know

[Zilch]

So how do speakers of the so called "D'Appolito" style, with a HF driver between two identical mid-bass drivers, one above and below it, fit or not fit into the idea you have presented?

D'appolito actually takes advantage of the same, to use the primary lobe in "steering" the dispersion in a desired manner. The design parameters were derived from studying and understanding these effects, and the application is very specific, down to the crossover order used with it, even.

So long as you are on axis with the tweeter, you're equidistant from both drivers, and the lobe controls from there. The drawing has been posted several times in these forums, and there is a substantial literature regarding the MTM configuration design technique.

The technology of line arrays is also fascinating reading. It deals with many of the same issues in similar ways. Here, for example, is one on stacking 2370A horns:

http://www.jblpro.com/pub/technote/tn_v1n07.pdf

Stacking L100s, tho, merely worsens the chaos....

[coherent_guy]

I see, thanks. Interesting paper too, and you remembered I have 2370s, aww shucks.

Acoustics is always a curious and un-intuitive or unpredictable science it seems. Or is that psycho-acoustics?

For instance, the mere 3db increase in SPL when adding a second transducer in a system. Acoustics sure isn't mechanics, and a little knowledge of it is dangerous.

[opimax]

Is there a standard in center channels for Surround systems? I have a kef

http://www.kef.com/products/XQ/xq2c.asp

which has 3 "woofers" across the front, the center is a co-ax and a super tweeter on top. It is called a 4 way but their are 5 drivers, something has to be a dupilcate doesn't it?

One of the senior experts recently said for HT 2 subs has become the minimum for higher end systems. Does the dupication of different part of the spectrum matter to the part of sound quality that is disrupted by multiple drivers? would this then also work for the above Kef but the XO is at 350 not under a 100 for non-directional sound?

Let me sum up, I am confused and not sure if I even know enough to be dangerous. Sorry If i am being a PIA, not my intention

Mark

[coherent_guy]

Good point, as in how does a center speaker, a "horizontal D'Appolito" configuration fit in this? At least from my seat.

I'm not sure what you mean about a standard for center speakers. The horizontal configuration is most commonly seen, although I've heard of "normal" speakers used as centers. Most center speakers are bandwidth limited in the low bass and many times set to "small" in size in the surround sound processor or receiver.

Your KEF has two woofers, with the center located speaker being the midrange and tweeter, with a KEF Uni-Q tweeter coaxial mounted. The center speaker is not operated at low frequencies. The specs show this clearly, as the center speaker is a 6 inch unit operated from 350 to 2.7kHz, whereas the woofers are 6.5 inch units. Your four way, five driver system has two woofers. Like some new JBLs, KEF has joined the super tweeter bandwagon and added one on top, people seem to either love that or hate it.

If the horizontal configuration of most center speakers has a special significance, I've never seen it discussed, but I may have missed it. That configuration may simply be used since its form works with the horizontal architecture of television screens, particularly 16:9 aspect ratio HD sets.

I can't answer your main question except to say that all the center speakers out there like yours and mine either have no problem, or are all messed up.

[Zilch]

Good point, as in how does a center speaker, a "horizontal D'Appolito" configuration fit in this? At least from my seat.

You've called it correctly. The D'Appolito lobe is then horizontal, as vertical doesn't mean so much. HT viewers are basically stationary, vertically. You want a wide, uniform horizontal field from a center channel speaker....

Still looking for the drawing, here. I may have to scan it....

[coherent_guy]

Given the wide horizontal dispersion pattern, I really like my SVA Centers ability to be aimed at the listening position in the vertical plane, with it's adjustable rear leg. A great idea I've not seen used elsewhere, I wonder if JBL came up with that?

Opimax, how do you like your KEF center channel with super tweeter?

[Fred Sanford]

My Canton centers have adjustable rear legs, too. They refer to it as a "stabilisator" in the manual.

Just gave a friend a nice KEF center, something in the Q series with a coaxial driver. Nice speaker, good sound & good power handling.

je