Nominal Impedence and Amp Taps

My speakers spec sheet mentions a 4ohm nominal Impedence. My amps have 2/4/8 ohm taps, does this mean the best amp tap to use is 4ohms?

Ive always wondered this.
Yes, in most instances. But if your speakers have unusually large impedance swings (like some esl's do) you can try the other taps and determine what sounds best to you. My speakers have a nominal load of 5ohms with swings from 1.5 to 32 ohms. The 4 ohm taps on my amp sound better than 8 ohms. Wish I had 2 ohm taps like you just to hear any difference.
Many speakers do not have uniform impedance across the full audio spectrum. The nominal value is just an average. You may have to experiment for the best sound. What is your equipment... tube/solid state, electrostats/panels, etc.? I would start at 8 ohms and work down. If the sound is lifeless, or conversely, out of control, you have the wrong setting
thanks for the help so far, my amps are Sonic Frontiers Power 3's and the speakers are Duntech Black Knights (Dunleavy). The amps came to me in 8 ohm mode, but until today I didnt want to mess with them, today they went into 4 ohm mode. Ive tube swapped 3 days ago, so I cant tell what the differences Im hearing are from.
Hi Justlisten Duntech may be able to give some advise when you mention the name of your amps. I have a Anthem amp1 that has 4,8, and 16ohm settings. My spkrs are Meadowlark Kestrals that are 8ohm. When I tried the 4ohm tap the spkrs didn't sound right at all. I also called Meadowlark and they told me the 8ohm tap would be the best. Also since you put new tubes in your probably won't have a clue untill the tubes settle down. Best of luck
My amp has 2,4, and 8 ohm taps and my speakers are N802's which are rated at 8 ohms but I've heard that they can dip down to around 3 ohms in the bass. The amp manufacturer, VAC, suggests trying the different taps to hear which works best. I tried all the combinations including running the bass at the lower ohm taps and the treble at 8 ohms whilst using the bi-wire configuration. I obtained the best sound from the 8 ohm tap and single wired to the speaker.
No! Several factors come into play. Damping factor increases as the impedance of the tap decreases. Many are willing to run 8 ohm speakers from a 4 ohm or lower tap to reap the rewards of the increased damping factor at the expense of ultimate power. Many amps have the feedback optimized for only one of the taps, usually 4 ohm. The audible effects of using a different tap will vary with impedance and phase angle of the speakers selected. As previously mentioned, speakers have varying impedance and phase angle with frequency and output transformers are likewise, frequently non-linear. The best advice is to experiment and let your ears decide.