Soundlab speakers with sub woofers?

Bob, part of the disconnect here between you and Ralph is due to terminology. Including:

1)Strictly speaking, speaker efficiency refers to acoustic power out vs. electrical power in. It is also commonly used to refer to SPL at a given distance vs. electrical power in. SPL vs. voltage in is sensitivity, not efficiency.

2)When Ralph says that an amp "makes power," he is referring to how much power the amp delivers to the speaker.

3)When Ralph says that a Sound Lab is driven by power, not voltage, he is asserting that for the speaker to produce flat frequency response in its acoustic output, it must receive electrical power (not voltage) at its input that either is or approximates or approaches being flat as a function of frequency.

As you realize, given the huge decrease in the speaker's impedance between the bass region and the upper treble region, no. 3 can only occur if the voltage at the amplifier output terminals/speaker input terminals is NOT flat as a function of frequency.

Also as you realize, nearly all solid state amps will produce output voltages into varying load impedances that are essentially flat as a function of frequency, as long as the amp is operated within the limits of its maximum voltage, current, power, and thermal capabilities.

While on the other hand the interaction of the output impedance of a tube amp and the variation of a speaker's impedance as a function of frequency will result in nearly all tube amps coming at least a little bit closer to supplying power (not voltage) into a varying load that is flat as a function of frequency, when the amp is operated within its capabilities.

Also, the MAXIMUM power capability of a solid state amp into high impedances can generally be expected to decrease in close proportion to the impedance rise above 8 ohms. While that decrease will usually occur to a considerably lesser extent with tube amps, and an increase may actually occur with some amps over some range of impedance increase. Ralph is correct that a solid state amp rated at 600 watts into 8 ohms will generally be able to deliver only about 150 watts into 32 ohms.

Best regards,
-- Al

"Also, the MAXIMUM power capability of a solid state amp into high impedances can generally be expected to decrease in close proportion to the impedance rise above 8 ohms. While that decrease will usually occur to a considerably lesser extent with tube amps, and an increase may actually occur with some amps over some range of impedance increase. Ralph is correct that a solid state amp rated at 600 watts into 8 ohms will generally be able to deliver only about 150 watts into 32 ohms."

Looking at the above example, is it correct to assume that if the amp has no trouble driving the 600 watts into 8 ohms, it will have no trouble driving higher resistance with less watts, like 150 watts at 32 ohms? The logic being that even though the amp is not producing as much power, the higher resistance makes it easier for the amp to handle. Discussion on this topic doesn't come up too often, where as there's plenty of talk on the other end of this; needing a more powerful amp to drive low resistance loads. I've always assumed that if an amp is OK driving a load at a given resistance, like 8 ohms, it will have no problems with loads of a higher resistance.

ZD, yes, that all sounds right to me, with respect to the sonic performance of the solid state amp in itself. That is a separate issue, of course, from the question of how suitable the amp may be for use with a speaker which doesn't want to see constant voltage as a function of variations in load impedance.

Also, although you are referring to solid state amps, I'll add that in the case of tube amps having output transformers a caveat might be that if there is a substantial mismatch between load impedance and the impedance the output transformer tap being used is designed to work into, there may be a significant increase in distortion (as well as a reduction in maximum power capability, relative to what it would be if that match were optimal). Ralph can most likely provide a better quantitative perspective on that than I can.

Best regards,
-- Al

On most tube amplifiers its a good idea to try the Sound Lab on the various taps of the output transformer to see which works best.

Some transformers can ring if not properly loaded- so if you are on the 8 ohm tap and the amp is playing into a 30 ohm load on a bass note, you may get increased distortion (lower ordered harmonics) that might cause the amp to sound warmer than is actually correct. It depends on the design of the amp as to whether there will be a significant loss of power with such a mismatch, but IME usually the loss of power is slight. If the amp has negative feedback most of the distortion will be controlled but that can be a double edged sword as with more feedback comes a greater tendency to behave as a voltage source.

With our MA-2 (about 70% of our production in the last 20 years are driving Sound Labs) there is also a slight loss of power into 30 ohms (about 10 watts), but distortion is actually reduced into the higher impedances.

In short, this is a speaker that benefits more than many box designs from a slightly higher output impedance in the amplifier.

I heard a pair of Soundlab Ultimate 1's driven by a pair of CAT mono block amps in a fairly large room of an audio friend.

Absolutely no need for one or more subs.

I have owned several other stats, and even tried the ML Depth sub with CLS11z when I had them.

I preferred the CLS without the sub.
Less bass wallop, but also a more unified sound.

When I ran a full out HT set up with two pair of CLS and the Theatre centre channel the Depth came into it's own on the .1 end of things.

I also had two Velodyne ULD 12 on a pair of Quad 63, that added more bass but again you gain in some areas and lose in others.

If your stats go down to the mid 30's as the ones I have now do(Acoustat 3, servo amped)I don't think you will need to add a sub.