Simple Ohm Speaker Question

hearing

Hi,

I just bought a Sherwood RD-7108 Receiver, and already have Polk R15 Bookshelf speakers (as well as an older Technics rack system). Then, I noticed that the speakers are 8 Ohm, and the receiver says 6 Ohm.

Are they compatible, with these ratings? I am just going for a simple audio setup with just the 2 Bookshelf to start. Maybe later I can use the 3-foot tall Technics speakers(also 8 Ohm), but I may just throw those away.

Anyway, is it OK to connect these 8 Ohm speakers to the 6 Ohm receiver?

Thank you, and any other suggestions are appreciated :-)

unc2701

you're fine- w/ solid state gear as long at the speaker impedence is higher than your amp's rating it'll work great.

thehaens@cox.net

I have a question as well regarding impedance, I have noted that on Polks spec's on the RT-16's it has a "nominal impedance" of 8 ohms. However, I hooked up my VOM to the terminals, and I get a 3 ohm reading, on both speakers. I have also checked my SDA-1A's and they are also 3 Ohms. I have inquired by PM to another polk member to check out his SDA 2.3's and they read 4 Ohms, but the manual says 8 Ohm nominal. Can I gather that when you hook up two channels to an amp, the amp sees them in series? Effectively seeing a 6 and 8 Ohm load respectively? If anyone can shed light on this, it would be appreciated, and would be curious to know if other models of polks read a different impedance on the meter than what the manuals say...thanks

scott

RuSsMaN

DCR and nominal impedance are not the same. You are measuring DCR at the terminals. Nominal impedance is an avg throughtout the freq response of a speaker.

thehaens@cox.net

Thanks Russ, question DCR? So are you saying the impedance is greater as the signal is applied?

unc2701

all you're measuring is the resistance to a DC voltage of the speaker coil. If you to to partexpress and look at the specs on some of the speakers, you'll see that they usually include one of the impedence across all frequencies.

The nominal impedence is the speaker makers way of telling how hard the speaker is to drive in general...

RuSsMaN

No, the impedance changes at certain frequencies, more drastically at the top and bottom end of a specific drivers range.

thehaens@cox.net

O.k. then I should be good with putting my two RT-16's wired in parellel then. I am using them as the center channel, and was worried when I checked the impedance on the terminal as reading 1.4 ohms. So instead I ran them in series. The manual to my Marantz Mono amp says it is stable to 4 Ohms so with that I should be able to run them in parallel with no problem. I am going to hold you responsible if the amp melts Just kidding of course. Actually having them in series hasn't really been that much of a deal, just had to turn up the center a bit to coincide with the other channels.......thanks

scott

unc2701

Yeah, just keep an eye on the temperature- if the amp seems to be running hot, then switch over to series.

thehaens@cox.net

Originally posted by unc2701
keep an eye on the temperature-.

Can you you see the temp I hear you, actually will wire them up tonight and see what happens, worse case scenario is that the fuse will blow, (hopefully), before any damage to the amp...