8mm Forum: Question about Elmo speaker.

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Posted by Hamid Moqadam (Member # 1715) on October 22, 2009, 06:52 AM:

Hello,

I have two question regarding Elmo twin speaker:
Has anyone want to sell ES-1200 brand new condition? (Which I think has 12-inch size woofer).

And if I join the twin-speakers together to become mono, wouldn’t harm the internal projector amp since the two speakers now draw more power than just one speaker?

Im not technical, the reason im asking this because joining two speakers together make them one 16 ohm (since each one have 8 ohm), which above power amp rated 8 ohm and 20 watt RMS! Like B&H 2585 16mm projectors has only one output jack.

Anyone care to answer.

Many thanks.

Posted by Michael Beyer (Member # 1143) on October 22, 2009, 06:59 AM:

Hi Hamid,

if you join two speakers together, it's not the double resistance, it's the half ! So there will be 4 Ohm, not 16 !
But I don't know how the projector amp will react if it is made for 8 Ohm.

Regards,
Michael

Posted by Steve Klare (Member # 12) on October 22, 2009, 08:10 AM:

In series connection: 16 Ohms.

In parallel: 4 Ohms

In series: half the available output power

In parallel: output stage of projector audio circuit-BOOOM!!!

It would be better to allow the projector to drive an Amp, and have the Amp drive the speakers.

Posted by Michael Beyer (Member # 1143) on October 22, 2009, 08:24 AM:

Steve,
I don't understand the difference. Perhaps I change series and parallel ???

I think Hamid uses an mono-projector.
So he can only connect one speaker with 8 Ohms.
If he will connect one with the other speaker and then to the loudspeaker-out of the projector, he will be 4 Ohms (in series ?).
Parallel is for me to connect each speaker with the projector (like an hifi-amp).
So for me is BOOM if he connected in series...

Posted by Steve Klare (Member # 12) on October 22, 2009, 08:40 AM:

A series connection is a big loop: one connected to another to another without branches. The resistances add together, the voltages divide on each device, the current is less, the individual power is less and the total power is also.

a parallel connection is all the circuit elements are connected together at a common point on both sides of the power source. The voltage is the same on each one, the resistances divide, the individual currents add up and the total is more. The total power goes up.

Michael, are you the guy that had that really good "home cinema" video on YouTube last year?

Posted by Claus Harding (Member # 702) on October 22, 2009, 08:43 AM:

Yes, 4 ohms bad [Big Grin]

This one falls under: if you have any doubt about how you are wiring it, dont. Because once the amp is blown, it's gone.
Besides which, the amp doesn't have much clean power to begin with, let alone when running two speakers off it.

You get much better sound with an external amp (with tone controls) powering the speakers, so why even risk it?

Claus.

Posted by Michael Beyer (Member # 1143) on October 22, 2009, 08:56 AM:

Steve,
no, I am not.
My home cinema was built in 2009. I posted the pictures this morning into the "screening room"-thread.

Now I understand the difference.
But I think he will make a series and not a circuit...

Thanks,
Michael

Posted by Hamid Moqadam (Member # 1715) on October 22, 2009, 12:31 PM:

Thank you all for wonderful information.

Im afraid not getting good picture yet!

Let me clear again just to be sure, both B&H 2585 and Elmo ST-1200HD have only one mono "ext speaker" output jack rated 8 ohm. I have been told Elmo twin speaker (which is accessories in ST-1200HD manual) designed to work together by connecting one speaker to another (by cable), then one cable from one speaker to projector "ext speaker" output. This way projector amp "ext speaker" output feed two speakers together but as mono. Unlike GS-1200, which has two separate "ext speaker" output as stereo.

I have been told these twin speaker designed for GS-1200, and also for ST-1200HD. So shouldn’t be perfect match? There are many external amp&speaker! But maybe old design sounded more natural.

Steve! Boom mean damage internal amp? So using both speaker at once is better?

Many thanks.

Posted by Steve Klare (Member # 12) on October 22, 2009, 12:49 PM:

Well, if the two speakers combined together wind up a total of 8 ohms, you are fine. If they are 16 then you are going to get less volume out of the pair than you would with a single 8 ohm speaker. If they wind up 4 ohms together then the projector is going to try to put out twice the power it was meant to and you will overheat the output amp.(Booom!)

If this pair was designed for operation in an 8 ohm system, it's probably two 4 Ohm speakers wired for series operation. You can tell that by looking at the markings on the speakers and tracing out the wiring. (big loop, no branches....)

The thing about buying these is that speakers don't age terrifically: you may find that pretty soon they will begin to buzz because of material failures in the cones. If you want them for collector's value that's OK, but if you really want to use them a pair of new speakers may leave you better off.

Posted by Hamid Moqadam (Member # 1715) on October 22, 2009, 04:26 PM:

Thank you Steve for clearing this. I have perfect picture now. I think you made good point about these speakers age fast!

Posted by Kevin Faulkner (Member # 6) on October 23, 2009, 04:29 AM:

If Elmo followed the same layout as with the ES1000 which I own they are 16ohm units and are designed to either be used as a Stereo pair or in paralel on a mono projector. This will give 8 ohm when connected in paralel and will suit most amplifiers even if just one of the units is used on its own.

Check what is written on the rear of the large speaker.

Kev.

Posted by Hamid Moqadam (Member # 1715) on October 23, 2009, 12:30 PM:

Hello Kavin, Thank you for helpful thoughts.

Well i found good speakers but probably are later models, tweeters num:65PH14SD, and speakers num:EAS-25P08SA.

The seller confirm speakers marked 16 ohm.

Many thanks.

Posted by Winbert Hutahaean (Member # 58) on October 23, 2009, 12:47 PM:

Does this speaker will produce enough bass? Because as far as I remember this speaker has only 1 way.

regards

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