When an amp puts out 90 watts....


into 16, 8, or 4 ohms, what does that tell me about the amp? I am use to seeing an amp's output increase, sometimes even doubling, when going from say 8 ohms into 4 ohms.

The amp in question is the Copland CTA 506.
finsup
If you start with a reasonably powered amp and know the speaker impedence and efficiency are also reasonable, and act reasonably, you don't need to spend another moment on this power issue. Copland stuff is well regarded and I suggest you just set the whole system up and avoid the avalanche of opinions you could subject yourself to regarding room treatment, tiny wooden speaker wire bridges, gigantic power regenerators, fuse direction, and hairstyle tips...however, MY opinions are to be cherished as True Art and a gift to the reader...I'm a giver.
You should have just said so. List your whole system and some basics on your room. I'm sure someone will be able to point you in the right direction. As far as room placement goes, thats a great place to start. You'll learn a lot just doing that alone.

Maybe I will start another thread later but really, my reason for asking stems from reading a couple of different amp threads. There was a lot of discussion about impedance, slew rates, etc. and some calling out others for wrong information, etc. I guess I just want to have enough information to be dangerous like some of you other guys. :)

But seriously, I could not remember any information about amps delivering the same power into different loads and that is why I asked. Now I know why that is the case.

If you start with a reasonably powered amp and know the speaker impedence and efficiency are also reasonable, and act reasonably, you don't need to spend another moment on this power issue. Copland stuff is well regarded and I suggest you just set the whole system up and avoid the avalanche of opinions you could subject yourself to regarding room treatment, tiny wooden speaker wire bridges, gigantic power regenerators, fuse direction, and hairstyle tips...however, MY opinions are to be cherished as True Art and a gift to the reader...I'm a giver.

Wolf, I am a true connoisseur of your nuggets of wisdom...
Not only is consistent power output typical of tube amps, but also McIntosh amps that use autoformers have a stable power into all impedences.
Not meaning to hijack my own thread but since Mjcmt brings up McIntosh and autoformers, I bought some Speltz speaker cables and an IC from him some years ago. I recall he was also offering something called a Zero Box.

I'll go and search on this topic and see what I can find, but does anyone have any comments on Speltz's Zero Box and under what circumstances using them might be of benefit. Again, I am unhappy with my current speakers: I don't know if it is the amp or the room, or I just don't like the speakers but I do think there might be a mismatch in my system.

System:
Speakers: PBN Montana XP
Ampilifer: Butler Audio 5150 (currently in use in 2-channel mode only)
Pre-amp: Lector Zoe
Source: Raysonic CD-128