Axiom Home Page Forums General Discussion Technical Questions is my receiver too weak to handle vp150 and qs8s?

hi everybody! this is my first post as a registered member, though i have been lurking for a while, as well as made a few posts. i have a vp150, and recently a pair of the m22ti's, and i must say that i really love the way these speakers sound, especially for their price. being a student doesnt really allow me a very large budget, so making a good purchase is very important to me.

i have a yamaha htr-5440 (65 wpc at 8 omhs, for 5 channels), which is just something i picked up from best buy. the receiver doesnt clip the vp150, which is rated at 6 ohms. im very happy that it works out. i was looking to complete HT setup with a pair of qs8s, but saw that they were also rated at 6 ohms. my question is will be my receiver be able to handle them along with the vp150 safely? or will i have to buy a more powerful receiever? for all i know, the vp150 already clips, just not very noticeably.

Fong

Welcome!

Your receiver should do just fine with the QS8s. I think people often get too hung up about this speaker ohm thing. All speakers have a variable impedance based on frequency. A speaker's rating is a "nominal" rating that usually means that the impedance does not dip below the rating (at least significantly). For a properly designed amp, (rated at 8 ohms) a 6 or even 4 ohm speaker (load) should not cause a problem. Problems did exist (in the olden days) when people used to connect 2 speakers to the same speaker posts - (i.e. no A and B speakers on the amp) and if you did that the wrong way (in parallel instead of series)[did I get that right Alan?], then the load could dip to 2 ohms or less and that WOULD be bad for the amp!

If you look at many amplifier ratings (of receivers) these days, you will often see a power rating at 6 ohms as well as or instead of 8 - and the power rating is higher at 6! (Gee, why is that - you ask? Answer: it's magic! no, er, it's marketing!) Well actually its physics (electronics), so let's just leave it at that.

All that said (or is it rambling?) Your receiver should do just fine.

Go get 'em! (the QS8s - that is)

Randyman

cool. i will get the qs8s. when i save up enough money that is :P

oh, and i believe that if you hookup speakers in series you would combine the loads, and raise the total impendence.

note: i just took circuits 1 this semester, and it was something that i learned : )~

Hi Fong,

Yes, you and Randyman are correct about series connection of speakers, but the weird thing that results with series connection is that the frequency response of the speakers then sort of tracks the combined impedance curve(s) of the two speakers with audibly bizarre and unpredictable results. Check your Circuits 1 equation for power output (volts, amperes, and ohms). But it's certainly safe for the output stage.

Randyman, you're correct about higher power output ratings at lower impedances (because there's less resistance, more current--amperes--flows, hence power in watts increases) EXCEPT for receivers that have switches for lower impedances. Those usually limit current output to protect the output stage from overheating, so actual power output in watts is sometimes dramatically reduced when the switch is in the "6 ohm" or "4 ohm" position.

In any case, your Yamaha will handle the QS8s without problems as long as you aren't trying to fill a very large room with 100 dB SPL levels.

Regards,

hmm...there is an impendence switch for 8 and 4 ohms on the back of my receiver. on the position i have it on now is for 8 ohms on the mains, center and rear channels. but if i flip the switch, my manual says that i should have 1 set of mains that are 4 ohms or higher each (or 8 ohms for each speaker if using 2 sets a/b), and 6 ohms or higher for the center and rear channels. would this switch limit the output of power if i were to set it on the lower impendence setting, or should i just leave it at the 8 ohms (for more power?)? because the switch seems to be pertinent to the speakers that i have/will buy.

Hi,
Leave the impedance switch at the 8-ohm setting because the VP150's lowest impedance is 6 ohms, and the receiver will be able to handle that without trouble.

It also would be prudent to use surrounds rated at 6 ohms or higher.

Regards,

hehe like the qs8s

Ha, ha. Now I didn't actually SAY that, did I?