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JVC RX-709V and 4 ohm + 8 ohm speakers.

R

Rockin Robby

Member
I am looking at a pair of Acoustic Research AR-91 speakers. They are 4 ohms and need big power, but my JVC has 100 wpc 8 ohms, so should be good. I have some other 8 ohm speakers on the second speaker output. I have read that some other amps don't like to power both sets of speakers at the same time if one set is 4 ohms and the other 8 ohms. My JVC RX-709V manual doesn't warn against this, but I am wondering if it could be an issue to run 4 ohm and 8 ohm speakers at the same time from the 2 separate speaker outputs.
Thanks for any help fellas!
 
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Not a good idea. It is extremely unlikely that the power supply and output section of your JVC is designed to handle a load of 2.66 ohms, which is what it will see if you run both pairs simultaneously.

I am very surprised that the manual does not address the topic of speaker impedance.

Note that I am assuming you mean that you want to run both pairs as "main" or "front" speakers. If you want to run one pair as fronts and one as rears, that is a different topic.
 
I'm having good success with a load matching speaker selector switch. It runs two pair of 4 ohm speakers on any receiver I have. And will run 16 pair when I want to. Not much use for that but can be good on some organ, big band and orchestra stuff. Not good for 4 piece jazz.
I don't think you will get away with it for very long with out the selector box.
 
Does that AVR have pre-amp, out?? Or if you have the manual?? See if it can drive low impedance loads?? I have a Technics SA-AX920 from 94 ish?? And thru some combination of pressing this button and that button and ... spinning around three times and saying "help me obi wan kenobi" you can get it into "low impedance mode." :)

Failing that and going full steam ahead ... anyway?? Prey for a great protection relay! If it has that ... it will kick in right quick! Remove the load and the unit will come back on. That worked for me with that particular unit ...but adding a separate amp to bypass the built in subwoofer amp worked much better.

My very old Visonic Sub One (Acoustic Suspension) subwoofer, is the only speaker I have that is "difficult" to drive! I still like it and added the equipment I needed to enable me to keep using it.

If you like the "Acoustic Research AR-91" speakers and most likely you will?? Then you should build another system around them, if your current AVR won't drive them or does not have the flexibility you need to make it fit?? The proper gear for the job ... works much better than "blowing crap up." :)
 
Rockin Robby said:
I am looking at a pair of Acoustic Research AR-91 speakers. They are 4 ohms and need big power, but my JVC has 100 wpc 8 ohms, so should be good. I have some other 8 ohm speakers on the second speaker output. I have read that some other amps don't like to power both sets of speakers at the same time if one set is 4 ohms and the other 8 ohms. My JVC RX-709V manual doesn't warn against this, but I am wondering if it could be an issue to run 4 ohm and 8 ohm speakers at the same time from the 2 separate speaker outputs.
Thanks for any help fellas!
Click to expand...

Is it a 709V or 709VTN? Might be different, I don't know. Seems many of the V's listed are really VTN.
If Google images is correct, if you have the VTN model look at the rear of the unit where the speaker connections are.
Both places (mains and center/rear) state 8 ohm or greater.
Can you get away with running 4 and 8, maybe, maybe not.
 
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spark1 said:
Not a good idea. It is extremely unlikely that the power supply and output section of your JVC is designed to handle a load of 2.66 ohms, which is what it will see if you run both pairs simultaneously.

I am very surprised that the manual does not address the topic of speaker impedance.
Click to expand...

Yeah, me too! It just says power is 100 wpc @ 8 ohms. I wish I could know for sure.

quiet said:
I'm having good success with a load matching speaker selector switch. It runs two pair of 4 ohm speakers on any receiver I have. And will run 16 pair when I want to. Not much use for that but can be good on some organ, big band and orchestra stuff. Not good for 4 piece jazz.
I don't think you will get away with it for very long with out the selector box.
Click to expand...
I like this idea, thanks! Are there some good selector switches you guys can recommend?

Was also thinking of running 2 sets of New Advent Loudspeakers wired parallel on my other speaker output. They are 8 ohms each, so that would be another 4 ohm load then right? So that would be one 4 ohm load on each speaker output? Speaker selector switch prob best option? Are these powered? How do they work? Can they be used along with my Dolby PRO Logic rear speakers in "Phantom Mode"?
Thanks for your assistance.
 
Rockin Robby said:
Yeah, me too! It just says power is 100 wpc @ 8 ohms. I wish I could know for sure.
Click to expand...

I am quite sure your receiver is not rated for a sub-4ohm load. Get a selector with impedance protection. Or use additional stereo power amp(s) to drive the additional pair(s) of speakers.

BTW, those NLA's may be rated at 8 ohms, but their actual nominal rating should be around 6 ohms...and they can drop well down below 3 ohms at some frequencies.
 
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redk9258 said:
I believe it states 8-16 Ohms on the rear of the receiver.
Click to expand...

Yes it does.

spark1 said:
I am quite sure your receiver is not rated for a sub-4ohm load. Get a selector with impedance protection. Or use additional stereo power amp(s) to drive the additional pair(s) of speakers.

BTW, those NLA's may be rated at 8 ohms, but their actual nominal rating should be around 6 ohms...and they can drop well down below 3 ohms at some frequencies.
Click to expand...

Great info to have. Really appreciate the solid advice guys, thanks!

If anybody has a selector switch with impedance protection to recommend, that would be great!
 
This is what I use. I use two. From the small switch box. That's 16 pair at a time. The least power receiver I have is the Pioneer, 8 watts. It will run all 16. So there seems to be great leeway with the setup. For swapping receivers I use the Amco selector. None of this involves moving wires around. So you can listen to anything you want at anytime. If that's what one wanted to do. I assume you would use just one box.

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