Coincident with 8 ohm vs16 ohm

With a tube power amp, supposedly the only difference between the 4-Ohm tap vs. the 8-Ohm tap is that the 4-Ohm tap has more active secondary windings in the output transformer. Someone with more technical knowledge could maybe clarify this.

I don't doubt anybody's experiential findings, but to really get to the bottom of whether amp A does better in 4-Ohm mode or 8-Ohm mode, the SAME amp should be used for tests in both 4- and 8-Ohm modes. Amp A in 4-Ohm might fall on its nose compared to amp B in 8-Ohm mode, but too many other factors are involved to determine whether output impedance is at the root of the perceived differences.

Most solid state amps do not have output transformers (exceptions are many of the MacIntosh amps with their "autoformers") and have very low output impedances anyway. So, impedance output is basically a moot issue in most SS amps.

I would guess that some other factor is going on with the cj Premier 12's vs. the cj 11xs. In theory, all that's going on with lower impedance taps is more transformer windings in play. This usually translates to better control of difficult impedance load speakers, but perhaps a loss of transparency (maybe some additional phase shift--which may or may not be audible). With higher impedance load speakers, a lower impedance amp tap should not really affect its ability to “drive” the speaker per se.

I could be completely off on this. Maybe someone with more technical knowledge and experience in the area of transformers and impedance matching could maybe explain some of this stuff better.

In my system, the Super Eclipse III’s do better on lower output impedance settings at the amp and sound better with more power than with less. They simply eat up either larger tube- or SS watts with gusto. Their bass extension and control with the 510 watt Musical Fidelity kW-500 amp, for example, completely revamped my impressions of the Supers’ power and operating preferences.

I thank you all for your useful oponions,in theory if your amp
output empedance cover the exact or very near empedance scala of speakers this is the best amp-speaker synergy.
Some nominal 8 ohm speakers dip to 3 ohms in bass region (ie JM Lab)and if you connect your amp 8 ohm tap you loose some degree bass control and detail, and some nominal 8 ohm speakers dip to 4 ohm in high frequency region)(ie: Verity Sarastro)and again if you use 8 ohm tap of your amp you loose some opennes or airy highs if your amp has not enough power to overcome this caveat, that is why low or mid powered tube amps need flat empedance speakers for the best result, I do not know how empedance swing is there for Coincident speakers? and for the 4-8-16 ohm taps of tubed amps, less wire means better s/n ratio and clearer sond better soundstage in general so as long as your speakers empedance scala permit one should always prefer to use 16 ohm to 8 ohm,8 ohm to 4 ohm, as far as I know.

Kalan, I agree with your post regarding impedence:

"I would guess that some other factor is going on with the cj Premier 12's vs. the cj 11xs. In theory, all that's going on with lower impedance taps is more transformer windings in play."

I think my problem with using the P12's with the Super Eclipse 3's was due to the efficiency of the speakers. The P12's just didn't like to run with only a few watts of power output. My P12's drove my B&W N803N's with no problem and sounded great but I think they were within their desired operating power output while driving those speakers. With the very efficient Eclipse 3's, the P12's were idling and not sounding their best. I can push the cj 11xs and it's like a spotlight from heaven compared to the P12's.

Please don't take this the wrong way, but I never understand these threads. It's fine to ask for insight to share experience, but there is no way I'd use the input you get from people to determine which output tap to use.

In my mind, no matter who you are getting advice from, your mileage will vary. Their system (amplifier, loudspeaker cable, and loudspeaker) and tastes are going to differ from yours in some way. You simply MUST experiment on your own. For just about every speaker, its published impedance value is of little importance in relation to its impedance and phase angle curves, and even less importance in relation to how your particular amplifier is able to drive that load, using your speaker cables.

My solution is to try both, and evaluate each over a period of a day or two. Play a variety of music, and see which works better for YOU.

Good luck!!!

The Coincident Super Eclipses III will dip into the 6-Ohm region between 3k Hz up to about 5k Hz. Whether this dip in that frequency range is significant to most tube amplifiers, I do not know. The Supers may not be as efficient many of us think. My experience with the Supers and larger amps corroborate some apparent lack of efficiency somewhere. I believe that lower frequency impedance dips *may* be more influential on amplifier demand, but I am not certain about that.

Since I have amps that can be switched between 4- and 8-Ohm output impedance, they do seem to have better “control” on the lower setting. This probably means that the speaker dips below 8 Ohms. No positive effect would occur to take advantage of the lower output setting if the speaker did not dip into the below-8-Ohms region. Other tube amps (not just mine) with adjustable outputs yield the same results with the Super Eclipses as well.

When it comes to solid state, the larger the amp, the better the Supers seem to perform in terms of sheer control, dynamic envelope, and bass extension. The whole discussion about over all musical appeal with smaller, often times more refined amps vs. larger, brute force amps, is a whole other debate. I am addressing solely “drive-ability” here.

I would expect some possible sense of "mere idling" on a truly high impedance speaker paired up with solid state amplification, but not with tube amps. SS will (normally) only put out the required current to drive a given impedance load (not talking about SS with output autoformers, here), if the SS amp has the power reserves to deliver the current to begin with, that is. A truly high impedance speaker will possibly not "draw" enough current from a SS amp for the correct target tonal balance or dynamic punch to occur. But tube amps do not work this way. Standard tube power amps pretty much put out the same voltage no matter the impedance of the speaker load, or actually sometimes have *lower* output into lower impedance loads.

My experience with the Super Eclipses (owned the Mk I’s and currently own the Mk III’s) with both tube and SS amps definitely favors more power on the drive-ability score. I am puzzled as to why a higher-powered TUBE amp operating with 4-Ohm taps could not drive the Supers as well as a lower-powered tube amp with 8-Ohm taps. There must be other factors going on.

I believe I have the theories (or principles) correct, but I am open any new information that would shed light on what might be going on here.

Since a few of us have the same model of speakers as the originator of the thread, it does seem odd that we experience such different results. Bottom line…as I---and a couple of others---mention earlier, try different amps with different output settings (when ever possible) with your speakers and let your ears be the judge.