Connecting Speakers w/diff ohms in 1 Amp?

A

abedinthehouse

New member
Equipment:
(1) JBL JXR 125 [500 W to 1000 W into 4 ohms]
http://www.jblpro.com/catalog/general/Product.aspx?PId=91&MId=3
(1) Crown XTi 2000 [1000 W @ 2 ohms/800 W @ 4 ohms/475 W @ 8 ohms]
http://www.crownaudio.com/amp_htm/xti.htm
(2) Acoustic Audio Bookshelf Loudspeakers [700 W @ 8 ohms nominal]
http://cgi.ebay.com/Acoustic-Audio-8-DJ-Series-Bookshelf-Loudspeakers-/160433178020?cmd=ViewItem&pt=Speakers_Subwoofers&hash=item255a9005a4

I currently have the JXR connected to the XTi via speakon cable on the right channel.

What I want to know is if I can hook up the smaller bookshelf to the left channel on my XTi through pure copper wire/banana plugs (Series/Parallel Wiring) even though the two speakers are of different ohms? Will the XTi be able to find the right ohms for each set automatically or will I have to set it somehow?

Ive been very cautious about setting this up encase something goes wrong. Do you guys have any advice as to what I should do?

Thanks in advance for all your help, this is greatly appreciated.

----------------------------------------------------------------------

UPDATE:
Okay so I just got the speakers set up to my rig. 1 speaker wasn't working at first, but after a quick check turned out one of the wires wasn't making full contact, fixed it and now everything is working like a charm! Thanks for everyones help on this. This forum rocks! :):cool::cool::D:drunk::p;):):eek::cool::cool:
 
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If the amp is set in stereo mode then you have each speaker one to left and one on right you shouldn't have a problem ....just that you will not end up with a matched monitor pair and I think this is what you need to set your goals on.



:cool:
 
abedinthehouse said:
I currently have the JXR connected to the XTi via speakon cable on the right channel.

What I want to know is if I can hook up the smaller bookshelf to the left channel on my XTi through pure copper wire/banana plugs (Series/Parallel Wiring) even though the two speakers are of different ohms?
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No problem. Wire the two Acoustic Audio loudspeakers in parallel, and connect them both to the Left channel. That will give you a 4 Ohm load on the Left channel, to match the 4 Ohm load on the Right channel.
 
Harvey Gerst said:
No problem. Wire the two Acoustic Audio loudspeakers in parallel, and connect them both to the Left channel. That will give you a 4 Ohm load on the Left channel, to match the 4 Ohm load on the Right channel.
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Oh wow, I completely forgot about that. I hope it works, but (@moresound) as for the stereo....not really sure I know how to do that. I actually downloaded the JRX speaker configurations from the JBL site and uploaded it into my XTi. That shoudln't mess with it should it?

I shall do some investigating with the XTi monitor today...
if there's any other advise your guys could give me, that'd be great

Thanks again everyone [=
Your help is greatly appreciated.
 
moresound said:
Ya I may have not understood the question completely.:cool:
Click to expand...

Well I wanted to hook up the three speakers (1x JBL & 2xAcoustic) to my Crown, but they have different ohms (JBL=4ohm Acoustic=8ohm). I just wanted to know if that would cause a problem or not, and what the best way to do it was.


But as Harvey suggested, I guess I can just hook up the Acoustic in parallel and that should even out the load...just wanted some confirmation from others to be 100% sure. [=
Thanks again everyone
 
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abedinthehouse said:
Well I wanted to hook up the three speakers (1x JBL & 2xAcoustic) to my Crown, but they have different ohms (JBL=8ohm Acoustic=4ohm). I just wanted to know if that would cause a problem or not, and what the best way to do it was.

But as Harvey suggested, I guess I can just hook up the Acoustic in parallel and that should even out the load...just wanted some confirmation from others to be 100% sure. Thanks again everyone
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Actually, the JBL is 4 Ohms and the two other boxes are 8 Ohms each.

As far as wanting "some confirmation from others to be 100% sure," I did work for JBL a long time ago, so I have a little knowledge about speakers.
 
Harvey Gerst said:
Actually, the JBL is 4 Ohms and the two other boxes are 8 Ohms each.
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oops, got them mixed up. I edited it though

Harvey Gerst said:
As far as wanting "some confirmation from others to be 100% sure," I did work for JBL a long time ago, so I have a little knowledge about speakers.
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PERFECT! You really have no idea how grateful I am, this has been bugging me for months now, and I have not known anyone knowledgeable to ask until now. Thanks [=
 
abedinthehouse said:
...just wanted some confirmation from others to be 100% sure. [=
Thanks again everyone
Click to expand...

I have been designing big PA systems for years, which includes correctly matching power amps to speakers.

I will confirm that Harvey's advice is correct.

(However, those little speakers may not survive too many long hot parties at high volume.)
 
You have the correct answer, but let's investigate the principle:

How does the electric company know if you wire a 25W bulb and a 100W bulb to a 15A circuit? Answer: they don't, they just know the total load, and each individual parallel load draws current according to Ohm's Law (I = V / R). So long as your load on that branch does not exceed the breaker's 15A (100W/120V = .83A, 25W/120V = .21A, total 1.04A) rating, and your total house load does not exceed 200A, everyone will be happy :)

Similarly, so long as the parallel load on your amp does not exceed 2 ohm (actually most amps are happier at 4 ohm), your amp is happy. Parallel load calculation:

Rtotal = 1 / ( 1 / R1 + 1 / R2 . . . 1 / Rn )

which for loads *of the same value* simplifies to:

Rtotal = Rload / n

where n is the number of loads.

Now, each speaker may respond differently given its sensitivity, power handling, and so forth, but in terms of a load calc that's what you need to know.
 
mshilarious said:
You have the correct answer, but let's investigate the principle:

How does the electric company know if you wire a 25W bulb and a 100W bulb to a 15A circuit? Answer: they don't, they just know the total load, and each individual parallel load draws current according to Ohm's Law (I = V / R). So long as your load on that branch does not exceed the breaker's 15A (100W/120V = .83A, 25W/120V = .21A, total 1.04A) rating, and your total house load does not exceed 200A, everyone will be happy :)

Similarly, so long as the parallel load on your amp does not exceed 2 ohm (actually most amps are happier at 4 ohm), your amp is happy. Parallel load calculation:

Rtotal = 1 / ( 1 / R1 + 1 / R2 . . . 1 / Rn )

which for loads *of the same value* simplifies to:

Rtotal = Rload / n

where n is the number of loads.

Now, each speaker may respond differently given its sensitivity, power handling, and so forth, but in terms of a load calc that's what you need to know.
Click to expand...



Holy crap!
Now that is WAAY beyond my understanding. lol
But thanks for the help, Ill be sure to keep that formula saved for the day I do figure out how to use it properly.
 
moresound said:
What application are you to use them in?
:cool:
Click to expand...

Personal use, house parties, and sometimes parties for friends. Nothing too serious...well not yet anyway, if and when I do, I plan on getting a second JRX 125 and a JRX sub or upgrading all my equipment altogether.


Im actually trying to figure out how Im going to parallel wire these two small speakers. Im thinking get two banana plugs, connect one one top of another into one speaker, and have the first (top) pair of plugs go to the second speaker while the second (bottom) pair goes to my amp. Hope that works [=

Thanks for your help btw moresound.
 
Cool sounds like fun....just Google parallel speakers and you'll find a diagram to help you out with your set up.



:cool:
 
Yea thats what I did, looked up some videos too. Just had some concerns as to how to connect the wires, but hopefully what I have in mind will work....I'll find out soon enough I guess.
 
moresound said:
What do you mean to the speakers or the amp?
:cool:
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Well I know one speaker's + connects to the other speaker's + (via wire) before going to the amp.....I was just trying to figure out the best way to make that connection before it lead to the amp. I dont really have the equipment to solder the wires together so, I'm thinking about using some banana plugs.
 
That will work for easy set up but then you have the problem of accidental tripping over the wire and inadvertently unplugging it.



:cool:
 
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