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2 x 4 = 8 Ohm?

subterracineman

Standard Member
I think this is correct but could someone please confirm that 2 four ohm drivers can be linked in series instead of one eight. Would the volume, clarity etc be roughly the same? Can I then add the power handling together when marrying up an amp?
Thanks in advance
Kevin
 

BlueWizard

Distinguished Member
Having two speakers doubles the acoustical power output, but putting them in series means that each speaker only gets half the signal. So, first we double it then we cut it in half, and acoustically we end up back were we started.

Two speakers in series are only as loud as a single speaker driven by the same identical voltage.

But notice that series means each speaker individually only gets half the electrical power, so the combination of two speakers in series should theoretically be able to handle twice the overall power, before each individual speaker reaches its rate power limit.

So, two in series will be the same volume as a single speaker on its own, but the combination will handle twice the power.

As far as clarity, each speaker is working half as hard to produce a given sound level. That means across most of the range, the speakers are going to be clearer and more detailed because they are going to be less strained. This assume the speaker were clear and detailed to start with. This doesn't make bad speakers magically good.

Does that help?

Steve/bluewizard
 

subterracineman

Standard Member
Thanks that does help.

So just to clarify I wanna stick with 8 Ohm speakers and can wire 2 in series to double the power handling. Does this apply for 3-tripled,4-quadrupled? (more out of interest).

I'm gonna be building a 7.1 projector cinema in an underground part of our new extension (planning allowing) and will be building all the speaker enclosures into the walls.

I've noticed many surround systems have a couple of woofers in the centre but only one in the surrounds. I would prefer the aesthetic of this, I'm assuming I'd need the same woofer doubled for the front rather than 2 slighlty cheaper ones? I was thinking maybe smaller woofers from the same range say 6" at the sides and 5" centre?

Your thoughts appreciated

:thumbsup:
 

Jules

Distinguished Member
Actually, centre speakers with a horizontal woofer/tweeter/woofer driver array are a compromise. The manufacturers make them this way so they can be shorter and fit underneath a TV more easily, they don't make them this way for audio quality reasons (even though the marketing blurb might convince you otherwise).

The problem with most centre speakers is that the 2 woofers surround the tweeter and control its dispersion characterisics, consequently suffering from what is commonly termed 'lobbing'.

You get a much more consistent soundfield using 5 identical traditional speakers with the tweeter mounted above the woofer.
 

subterracineman

Standard Member
Mr you what? Lovely, I had a bath earlier and with the exception of what i believe to be a dry fart me pants remain spotless.
Ok vertical it is, leave the tweeter the room to do his thing. Thanks for that, sound quality is king.
 

BlueWizard

Distinguished Member
Well, Jules brings up a valid point. Ideal in a large room with a large screen and a large speaker system, we would want all five speaker to be literally identical. This is frequently done with some of the better M&K systems. The Center speaker, is just another one of the front speakers.

But, how often do you see that in everyday life? Not very often. Centers speakers are design to fit somewhere reasonably close to and either above or below the TV screen. Within the limits of the size and shape they must be, they do a good job, but acoustically they are not the ideal design. They are more a product of necessity.

A vertical MTM (midbass, tweeter, midbass) can actually work in your favor. But when you place that same speaker horizontally, you frequently get a dip in the response right at the crossover frequency, among other problems.

But, again, virtually no one is in a position to put a tower speaker in the center in front of their TV to act as a center. Though, believe it or not, some do just that.

Now, if your front speakers are MMT or WWT (M=midbass, W=woofer, T=tweeter; when used in combination with 'W', 'M' means midrange), then your center could either be a vertical MT or WT, or even, if you have the space, a MMT or WWT. Or, again if vertical, a WTW, or MTM.

But, few of us have the space for speakers that large under our TV. So, we are stuck with the compromise of a horizontal MTM design. Though do notice that on the better MTM designs, the Tweeter is not center on either the cabinet or on the other woofers. It is raised so it is above, to some extent, the woofers, and is offset in the cabinets. This provides real advantages.

Notice how the tweeter is off-center in this design -

Parts Express DIY Project

And even this design -

Parts Express DIY Project

Just a few thoughts.

Steve/bluewizard
 

Jules

Distinguished Member
But, again, virtually no one is in a position to put a tower speaker in the center in front of their TV to act as a center. Steve/bluewizard
Well, I blame the AV cabinet makers. They have no understanding of the needs of an AV enthusiast to properly accomodate any decent centre speaker.

Which is why I made my own which easily and neatly houses a normal 'tower' speaker as my centre.
(the angle at which the picture is taken makes it look like the speaker is still obscuring the very bottom of the TV... but in fact the top of the speaker is actually just below the bottom of the TV's bezel.)
 

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subterracineman

Standard Member
Ok the idea I've come up, thanks to your help chaps, is to leave a recess in the blockwork wall to mount the enclosure in, to be finished with the baffle flush with the wall. 2 mid woofers and a tweeter mounted M M T up the wall vertically. the wall above the speaker will serve as a projection screen and will be painted mdf. I'll have to start a thread to see if there's a special paint for this purpose.
 

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