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Post subject: 2 additional speakers to Passport 250
Posted: Mon Jan 07, 2013 11:38 am
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our band has the older P-250 (or PD-25) with only one output jack for LEFT and one for RIGHT, and to the already in place Fender unpowered speakers we'd like to add 2 powered KUSTOM KPC 10" 8 OHM speakers.

we tried connecting the custom's to the RCA stereo outs and the speakers just don't get loud - no matter what we do, and we know these speakers can go QUITE LOUD.

we discovered that using a 1/4" splitter on the left jack and put the 2 [unpowered] fenders to that and then daisy chained the customs off the right jack - and noticed that it works - but figured too much impedance [ohms] and so this is probably not a good idea.

what's our best solution?

thanks.


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Post subject: Re: 2 additional speakers to Passport 250
Posted: Wed Jan 09, 2013 1:41 pm
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I'm confused, since you refer to the speakers you are attempting to use both as "powered" and as "8 OHM". Usually, you talk about ohms for unpowered speakers. You talk about watts for powered speakers.

Powered speakers have one input for the line-level sound signal, and another input for AC power. They are "powered" or "active" speakers because they include their own amplifier. If your speakers don't plug into AC power, they are not "powered" speakers.

Unpowered speakers, or "passive" speakers have no amplifier built in. They are rated in ohms, which tells you how much "resistance" they have to being pushed around by the signal going into them.

In any case, you want an amp and speakers that are built for each other. The amp is designed for a given range of resistance. Too much or too little can damage the amp.

Hook up unpowered speakers to a "line level" signal, like the RCA outputs on your Passport, and you won't get much sound at all. "Line level" is the signal level going INTO am amplifier, which amplifies that to a much louder signal intended for passive speakers.

You ask for the best way to hook up additional passive speakers to your Passport. The best answer is, "Don't hook up additional passive speakers to your Passport." It can damage the amp, and you won't really get more sound out of it.

To make sound, you need to push and pull on the middle of the cones of the speakers. This takes watts. Watts measure how much work the electricity can do. Take the same number of watts and distribute it to more speakers, and what you get is a diluted signal. Twice as many speakers each make half as much sound as they would if you didn't double the number of speakers.

Basically, you have a Cooper Mini and you want to hook it up to a house trailer and take it for a ride. The Cooper Mini wasn't built to pull that much weight. Neither is your Passport 250. Just don't do it.

I use four speakers, but I do it by connecting the stereo line-out on my Passport 500 (which runs two speakers) into the stereo line-in on my Passport 300 (which also uses two speakers). I'm not hooking up one amplifier to four speakers. I'm hooking up two amps to each other, and each of the two amps is driving two speakers. So, I'm not just adding speakers. I'm adding watts.

If your added speakers really were "powered", you'd be adding watts, too. But it sounds like you are only adding resistance. That won't make it louder. It'll just burn out your amp.


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Post subject: Re: 2 additional speakers to Passport 250
Posted: Wed Jan 09, 2013 5:28 pm
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thanks for the reply. as you can tell - I'm kind of new at this.

the additional speakers are indeed powered...they have both an input for sound (XLR) as well as a power cable, like a PC.

I have tried connecting them to the RCA stereo outs, but without much sound coming from them.


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Post subject: Re: 2 additional speakers to Passport 250
Posted: Sat Jan 12, 2013 9:32 am
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Aspiring Musician
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I'm guessing that you may have used adapters to go from RCA stereo to XLR mono in a way that doesn't work. Realize that XLR uses three wires, as does stereo TRS (1/8" or 1/4" plugs with a ring between the tip and shaft of the plug). But the wires are not used the same way.

RCA uses two wires. One is signal and the other is ground. Adapters that go from stereo RCA (two RCA plugs, one for left - white - and one for right - red- channel) to either 1/4" stereo wire the two ground wires together to one wire on the other side and put each of the signal wires to one of the other two wires for the TSR end.

Meanwhile adapters that go from TRS to XLR assume that the three wires coming in are NOT stereo, but are instead "balanced", meaning that only one wire is signal, one is ground and the other is shielding for the cable. You need adapters designed to go from stereo (either RCA or TSR 1/4" or 1/8") to mono XLR, or your setup will fail. It's like pouring antifreeze into your gas tank, thinking that one liquid should work as well as another, right? Why would they make one liquid fit in the other tank if that weren't true?

You need to find someone who can get a line-level stereo output appropriately adapted to a line-level mono input.


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Post subject: Re: 2 additional speakers to Passport 250
Posted: Thu Jan 17, 2013 7:58 am
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thanks for this information - we went through our entire set up and discovered we were not cabled correctly in many places (we were using instrument cables EVERYWHERE - now it's the proper mix of Instrument, balanced, and speaker cables.

we made appropriate changes and joila!!! things are much better:

Result:

* Fender speakers are much louder now and we don't need to crank up the output as high (we cut volume setting in 1/2 - and are maintaining just as loud, if not louder sound).

* Powered Kustom's now have plenty of power

* we have cut out a 'whirling' sound coming from low frequencies on the MICs into the sound mixer

* we have pretty much eliminated feedback

this has been a great exercise to go through and we learned a lot - and I'm glad we didn't damage any equipment!!!


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