amp power & driver sensitivity in multiamp setup

Something that is missed from this conversation:

The driver is measured in sensitivity, not efficiency. As a result the impedance must be taken into account; in this case it results in the efficiency being not quite so high. You can't exchange the two specs unless the impedance of the drive is 8 ohms. So this is going to make the situation worse.

Second, adding more drivers will not change the efficiency at all although it will affect sensitivity adversely if the drivers are in series. However this means little to a tube amps with no feedback!!

By putting the two drivers in series all that will happen is 1/2 the power will be dissipated by each driver, resulting in exactly the same output as if one driver were to be used, assuming the same amount of power in both cases.

Based on what I've seen so far, the 2A3 amp will likely be OK for the tweeter, but for midrange you will either need a more powerful amp or a more efficient driver. If the driver were to be about 105db you might do OK as that would be about the same as if the amp had 10x the power. However if you insist on an SET for that, well there just isn't one that can do that sort of power and no go over 20% so this problem will need some rethinking IMO.

Thanks, Ralph. I don't think, though, that Lewinski was asking about adding more drivers or putting drivers in series. As I read it he was asking about the possibility of choosing a single 16 ohm driver instead of an ostensibly similar 8 ohm driver, and whether doing so would be beneficial with respect to maximum volume capability.

Best regards,
-- Al

Hi Al- got it. I really don't think so, although it would help the amplifier to have lower distortion. He would still need either greater power or a more efficient driver.

Ralph, sorry I missed your post. And thanks for chiming in!

Al is right: I was considering using a single 16 ohm driver.

Maybe using specific examples helps. The original 94dB/2.83V driver was a B&W FST. PHL Audio makes high sensitivity drivers, and I was considering some of their 6.5" and 8" midranges as well. For example 2520 is an 8" 4 ohm driver spec'd as 100dB/2.83V and the 2530 is the same but 16 ohm.

Also as example, I'm looking into Yamamoto A-08S (45 SET) and A-011 (2A3). These only have one set of speaker connectors, though. I'm looking into what kind of impedance they were designed for, but so far haven't discovered it.

BTW, what's the impact you would expect if I ran one channel on the 5 ohm tweeter and the other channel on a 16 ohm midrange? Would that tax the amp in any way?

Thank you!

Its probably that if the amp has only one output and no taps, that the 5 ohm load would result in less output than the 16 ohm load.

If you use drivers that are 100 db 1 watt/1 meter (PHY?), then you have a chance with the 2A3 amp but I have my doubts about the type 45 amp- realistically they only make about 0.75 watts.