Axiom Home Page Forums General Discussion Advice from Axiom Owners vp-150 8 or 6 ohm

I have a vp-150 which is a six ohm speaker, but the manual that came with it reads to set my reciever to 8 ohm.Is this right ?
Thanks, steve

Yes, that is correct. The switches don't seem to "match your receiver to the load", they just reduce the power that can go to the speakers so it's harder to play music with the volume up all day and fry the receiver. I forget the details but apparently there was some kind of liability thing and so lots of audio mfgs added those switches.

This is from Audioholics,

Impedance Selector Switches

"This so called feature, used by some manufacturers, is designed to prevent overheating of the receiver or damage to its output transistors because of excessive current flow. The manufacturer accomplishes this in one of 2 ways: 1) Stepping down rail voltage supplied to the power amp or 2) feeding half the signal strength to a voltage divider of power resistors. Both of these methods severely limit dynamics and current capability of the power amp. This results in an audible decrease in bass capability and dynamics transient sound because the 4 ohm setting effectively increases the receiver's output impedance. Unfortunately many manufacturers put these features on their products to ease customer concerns with driving low impedance loads and for safety reasons when getting UL approvals. Note: In order to meet UL requirements, a receiver cannot be rated down to 4 ohms without having this switch onboard. Receivers without this switch are usually rated down to 6 ohms. In most cases, well designed receivers can easily handle 4 ohm loads safely and efficiently. It is highly recommend to keep the impedance switch set to 8 ohms regardless of your speakers impedance and make sure your receiver has plenty of ventilation."

>>Note: In order to meet UL requirements, a receiver cannot be rated down to 4 ohms without having this switch onboard.

Ahh, THAT'S why HK and Denon receivers aren't rated for 4 ohms even though they can drive M80s happily...

Wonder how it works for big honkin' power amps. I don't remember seeing switches on those...

The Rotel 1080 has no such switch,I don't see a UL listing on it either.Maybe they just don't do the Underwriters Laboratories deal.

So would this also apply when i get the 80's and a seperate amp should i run it at 8 ohms.If i do run it at 8 ohms am i losing 200w since the amp is rated at 200w @ 8ohms and 400w @4 ohms.Also if i get the outlaw 770 7.1 can i run it at 4 ohms if the vp-150 and the qs8 are 6 ohm or do i run it at 8ohm?Or should i get a seprate amp for the 80's and run everything else off my reciever?

Sorry about all the questions but i,m new to seperates.
thanks ,steve

What receiver do you have now ? You could get an 2 channel amp for the M80s and run the rest of your system with your receiver,providing it has preouts to connect an external amp.

It is not not the amp that dictates the ohm rating it is the speakers.If you get a speaker that is rated @ 8 ohm like the M60s then the 200 watt amp will produce the 200 @ 8.The same amp running the M80s @ 4 ohm will then produce the 400 watts at 4.I haven't seen a amp that has a impedence selector switch on it.They normally have a good enough power supply as to not have to worry about a lower ohm speaker.

There is a pretty good thread here discussing the same thing.

thanks for the reply,
I have the yamaha 1400 it has pre-outs.One other question though if I have my fronts at 400w and the rest at 110 wont my fronts over power the rest of the system?

Steve

No,once you calibrate all the speakers they will play at the same db level.

At the risk of sounding dumb.If all the speakers will play at the same level where's the benefit of having a 400w amp would i then need a 400w amp for all speakers to hear the benefits?

Your patience is appreciated like i said i,ve never used seperates.in the past i just bought a reciever and speakers, hooke them up and bam sound.

Steve