help with receiver/speaker mismatches and powered sub setup - AVS Forum
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post #1 of 3 Old 04-25-2013, 08:45 AM - Thread Starter
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So I'm in college, and my floor has an event we do ever semester to help people relax during finals. We've had a 5 piece set of older speakers sitting around in our floor storage closet without a receiver, until someone bought a receiver and had no idea what to do with it.

Of course the EE on the floor will know, right? /sarcasm

Anyways, the receiver (yamaha rx v390) has a 8 ohm minimum requirement for all the outputs, and 80 watts per channel at 8 ohms. The speakers are as follows:

2 front @4.2 ohms
1 center @ 5.4 ohms
2 satellite @ 4.4 ohms

the receiver dynamic output is 8/6/4/2 ----> 80/95/120/150

The setup currently plays, but I don't want the receiver to overheat and kill itself. So would it work for me to get say 4 ohm 100 watt resistors and add them in series to the speakers? Or these here in parallel with each other and then in series with speakers?

Also, I was looking into getting a powered sub with speaker level inputs. Since that hooks in between the receiver and the fronts, will that add resistance to the front lines?
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post #2 of 3 Old 04-25-2013, 10:34 AM
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Quote:
Originally Posted by caboose rvb View Post

So I'm in college, and my floor has an event we do ever semester to help people relax during finals. We've had a 5 piece set of older speakers sitting around in our floor storage closet without a receiver, until someone bought a receiver and had no idea what to do with it.

Of course the EE on the floor will know, right? /sarcasm

Anyways, the receiver (yamaha rx v390) has a 8 ohm minimum requirement for all the outputs,

Where do you find that?

I've searched the entire user's manual and fail to find any such statement. Where do your find it?
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and 80 watts per channel at 8 ohms.

That is one of many power ratings for this AVR. On the spec sheet it uses 30 watts as a reference level for specifying THD from the CD/Tape/LD-TV-VCR to speaker outputs. Does this mean that it is limited to 30 watts when using those inputs?
Quote:
The speakers are as follows:

2 front @4.2 ohms
1 center @ 5.4 ohms
2 satellite @ 4.4 ohms

The receiver dynamic output is 8/6/4/2 ----> 80/95/120/150

Dynamic power more closely resembles using the AVR to play music. For regulatory reasons many of the other specifications are obtained on a test bench using a steady pure tone, driving a resistive dummy load. That does not resemble using the AVR to play music into speakers.
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The setup currently plays, but I don't want the receiver to overheat and kill itself.

With adequate ventialation the AVR is probably not even breaking a sweat!

Quote:
So would it work for me to get say 4 ohm 100 watt resistors and add them in series to the speakers? Or these here in parallel with each other and then in series with speakers?

No. As I've been hinting above, your AVR is fine with 4 ohm speakers for playing music. Adding those resistors will reduce the tone quality of the speakers and also put additional stress on the AVR for a given amount of sound output from your speakers.

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Also, I was looking into getting a powered sub with speaker level inputs. Since that hooks in between the receiver and the fronts, will that add resistance to the front lines?

Unfortunately this AVR lacks any RCA jacks for LFE or subwoofer output. What you suggest is your only option, and its a poor option at that.
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post #3 of 3 Old 04-25-2013, 11:23 AM - Thread Starter
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Quote:
Originally Posted by arnyk View Post

I've searched the entire user's manual and fail to find any such statement. Where do your find it?

It isn't listed in the manual, but on the back of the physical AVR it says 8 ohm min for the center and rears, 8 ohm min A or 12 ohm min A+B fronts.

But as it will pretty much be used for music, the dynamic power seemed close enough (not double like the 2 ohm) that it seemed ok. I just don't have any experience with sound systems so I wanted to check.

And yes, I have read around enough looking for answers that I realized a powered sub with the inputs I have wouldn't provide great quality. We're currently experimenting with some unpowered subs and while it adds enough bass for our standards it also plays everything else, and a powered sub seemed easier to work with than trying to get a passive crossover working.

Thanks for the help smile.gif
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