Connecting Multiple Sound Sources to KRK RP5 G2

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Connecting Multiple Sound Sources to KRK RP5 G2

Postby gamblor » Tue Nov 15, 2011 3:37 pm

Whereas the KRK RPx monitors have multiple inputs on the back, is it OK to have multiple sources connected simultaneously? Being the smart person that I am, I tried this last night before asking questions. I had one source plugged into the balanced TRS input and the other into the unbalanced RCA input. Everything sounded fine and normal, with absolutely no noise being introduced into the monitors.

Is there a chance that I could damage the monitors if I maintain this configuration? The sources will rarely be playing sound simultaneously. They will both be connected and turned on at the same time though.

I’m looking to avoid purchasing a passive line selector. So far everything sounds right, but I figured it’s worth asking the question.
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Re: Connecting Multiple Sound Sources to KRK RP5 G2

Postby RoadDog » Wed Nov 16, 2011 10:45 am

The only word I don't like is the word "rarely". I would prefer to see the word "never" instead.
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Re: Connecting Multiple Sound Sources to KRK RP5 G2

Postby Mathieu Benoit » Wed Nov 16, 2011 12:43 pm

gamblor wrote:I’m looking to avoid purchasing a passive line selector.


I thought you were made of $40 bills? Alain can probably build you one.
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Re: Connecting Multiple Sound Sources to KRK RP5 G2

Postby Alain Benoit » Wed Nov 16, 2011 5:14 pm

Again you have to go back and think of the impedance and loading issues.
Then get back to me.

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Re: Connecting Multiple Sound Sources to KRK RP5 G2

Postby gamblor » Thu Nov 17, 2011 2:25 pm

I asked the question to KRK's tech support and they responded saying that it's no problem. The answer didn't do much to help my technical understanding of the problem though.

Alain. In terms of impedance issues, I understand that each input/output situation works on its own. See below.

For the source going into the TRS input: Input impedance = 10 k-ohm, Source impedance = 51 ohm, Source Signal Level rated @ Prof. Line Level

For the source going into the RCA input: Input impedance = 10 k-ohm, Source impedance = 1 k-ohm, Source Signal level rated @ commercial line level

While I see that each of these situations should work on its own, I'm unable to understand what the consequences are if both sources were connected and playing at the same time. By not using a line selector, I do run the risk of accidentally having both sources playing simultaneously. It would be nice to have the peace of mind to know that it won't hurt anything if that happens.
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Re: Connecting Multiple Sound Sources to KRK RP5 G2

Postby Alain Benoit » Fri Nov 18, 2011 6:06 am

You're definitely making progress into understanding impedance and loading.
I believe that were both of your sources to be fed to the inputs at the same time they would be actively summed with the potential of phase alignment issues.
This is due to the two different types of input each having their own buffer circuit.

In the end all is fairly well, I'm just glad you understand loading concepts more now.

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Re: Connecting Multiple Sound Sources to KRK RP5 G2

Postby Christian LeBlanc » Fri Nov 18, 2011 11:43 am

Just in case anyone else is playing along at home, here's a handy FAQ I found that may help explain things (worked for me, anyway).
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Re: Connecting Multiple Sound Sources to KRK RP5 G2

Postby Alain Benoit » Fri Nov 18, 2011 6:19 pm

So now do you see why if your KRK did not have separate inputs this would have been a bad idea? One source would have been loaded down by the other.
Also the statement in the article you linked about transformers not being ideal as DI's compared to active ones is FALSE, the author is for some reason using a shitty ass Radio Shack 'DI' as opposed to a professional one. I assure you that there is nothing wrong with the primary impedance of a Jensen equipped radial DI for example.

Any doubts about the quality of a good passive DI, just read here.

Also.

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Re: Connecting Multiple Sound Sources to KRK RP5 G2

Postby Alain Benoit » Thu Nov 24, 2011 10:14 pm

Word!
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Re: Connecting Multiple Sound Sources to KRK RP5 G2

Postby Christian LeBlanc » Fri Nov 25, 2011 12:16 pm

I don't think anyone wrote:anything

But Alain Benoit wrote:Word!

Sorry, I'm a goof :P
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