4 or 8 ohm?

[Tmielke]

Klipsh Forte speakers on my recently completed Kaiju.

Manufactures spec says nominal 8 ohm which is what I have the amp wired for. Metering the speaker terminals, I get 4 ohms.

Would I get any better performance from the amp wiring it for 4 ohms?

Thanks

 

[hmbscott]

First of all, I don't know if you will get better performance with 4ohms. But, I do know that putting a DVM on speakers will not give you a valid impedance reading. Speaker impedance is a function of frequency and varies a lot over 20 - 20k Hz. The meter reading is basically at 0Hz and means next to nothing. Klipsh says it's "8ohm compatible", which I take to impliy loosely that it doesn't drop enough below 8ohm to cause problems for an 8ohm output amplifier.

I have a Stereomour that I built with switchable speaker impedance (2, 4, 8, 16ohm) that I have used with several different speakers rated at both 4 and 8ohm, unfortunately not Forte's. What I found is that the sound difference between selecting 4 and 8 ohm outputs with the various speakers was very subtle. I generally very slightly preferred the impedance output that matched the speaker nominal impedance, but it wasn't dramatic. My expectation in your case is that the 8 ohm output is likely the better match for your speakers, but that 4 ohm would also work and likely would not sound much different.

 

[Paul Birkeland]

Here's the impedance curve of a Forte. The region between 80Hz and 300Hz is dipping down low, but the rest of the speaker not so much. If you listen at 8 ohms and things sound a little thin and lifeless, then I'd recommend rewiring for 4 ohm operation.

 

[Tmielke]

First of all, I don't know if you will get better performance with 4ohms. But, I do know that putting a DVM on speakers will not give you a valid impedance reading. Speaker impedance is a function of frequency and varies a lot over 20 - 20k Hz. The meter reading is basically at 0Hz and means next to nothing. Klipsh says it's "8ohm compatible", which I take to impliy loosely that it doesn't drop enough below 8ohm to cause problems for an 8ohm output amplifier.

I have a Stereomour that I built with switchable speaker impedance (2, 4, 8, 16ohm) that I have used with several different speakers rated at both 4 and 8ohm, unfortunately not Forte's. What I found is that the sound difference between selecting 4 and 8 ohm outputs with the various speakers was very subtle. I generally very slightly preferred the impedance output that matched the speaker nominal impedance, but it wasn't dramatic. My expectation in your case is that the 8 ohm output is likely the better match for your speakers, but that 4 ohm would also work and likely would not sound much different.

Thank you.