Speaker/Receiver Compatibility

I have an basic Onkyo AV receiver that is a little over 1 year old rated at 85 watts and 6 ohms nominal impedence. I have a chance to purchase some used PSB 7PT speakers at a good price. Although it would be somewhat more than I need, I am having a hard time passing them up due to the cost. I do not want to purchase a new receiver at this time.

From what I can find, the 7PT are rated at 6 ohms, but some testing that I read states that they regularly go below that.

I don't fully understand the impedence matching between speakers and receivers. Would driving these speakers with this receiver damage the receiver or speakers?

Any input would be appreciated.

Thanks.

You shouldn't have any trouble driving the 7PTs with your Onkyo. The 7PT have an efficiency of 91db which means they're a pretty easy load to drive. The impedance of any speaker will change with frequency. The problem with driving a lower impedance is it draws more current from the amp. Consistently drawing more current than the amp is designed for can cause output failure, power supply failure, excessive heat, etc... Many amps can handle lower impedances and more current for short durations such as explosions and heavy bass passages since heat-sink and/or fans help to dissipate the heat before damage occurs. If the price is that tempting, I wouldn't hesitate, PSB is a very good speaker. The Onkyo, although not my favorite receiver, falls into the top four or five reasonably priced mid-fi receivers I'd purchase. It should be a good combo.

PSB provides a more realistic Impedance spec with their products - rather than the "compatible with 8 ohms" nonesense. Nominal impedance is a useless figure.

Bfalls is correct, at all but the loudest settings, your receiver will drive those speakers with great ease. You will hit very loud volumes before impedance becomes a problem for you.

Basically agree with the above, but you asked for an explanation, so I'll try to give you one. I read it recently while reading a review of one of the 80xD series from B&W (the 802D, I believe). It seemed to have the single best explanation of what a hard-to-drive speaker is. When the impedance goes very low -- as it does with the B&W -- in trying to keep a consistent voltage drop over the speaker terminals, the current draw (I=V/R) goes way up, and thus, so does the power draw. So you have to have an amp that's capable of providing large amounts of current, which many are not able to do, so they distort instead.

That said, your PSB's are probably fine. If you wish to see for yourself, try to find an impedance plot of them.

Thank you all for the good information.

I would like to also get your thoughts on the following:

I also found a pair of Paradigm Reference Studio 60 v2 for about $100 less than the PSB 7PT. Has anyone listened to both? My time is split probably 50/50 between music and movies.

I am going to listen to both, but just wondered if you have any input.

Thanks again.

paradigms are nice, but I haven't listened to the psb 7pt...

for more detail on the impedance (correct me if I'm wrong)... the impedance will vary with the frequency due to the amount of back emf generated and you have a differential equation to solve...

I found this site, http://www.geocities.com/SunsetStrip...7/speaker.html but an electromagnetic field theory text book would probably help out a bit ...

heck, this may help out:
http://en.wikipedia.org/wiki/Electrical_impedance

later
Mike

Comparing specs, the Paradigm is very similar to the PSB. I really like the PSBs, especially the Stratus series Silver and Gold, but I think the Paradigms edge them out in build and sound quality. If you can get the Paradigms for $100 less, I wouldn't hesitate to jump on it. Whichever you choose you won't be disappointed.

I agree that Paradigm and PSB are very similar. Both are great, but personally I'd go for the Paradigm Studio's. They are phenomenal and are just a few notches above PSB.