How to fix my detailed, accurate but BRIGHT system

Al,

I cross-posted with you, so I hadn't read your post, before I posted.

Are you saying that an erratic electrical speaker impedance curve doesn't actually present a more difficult load to the amplifier in this case, because it's still within the acceptable limits of the amplifiers current delivering ability, and there won't be a problem with a frequency db imbalance, unless the curve dips far enough below the amplifiers minimal impedance, lets say 2 ohms?

Rich

Hi Rich,

That is sort of what I am saying, but I would put it a little differently. As long as the output impedance of the amplifier is small compared to the impedance of the speaker at the lowest point of its impedance vs. frequency curve, and as long as the amplifier is not called upon to deliver more current than it is capable of delivering, then a tonal imbalance will not result.

The fact that an amplifier can double its output power into 4 ohms, compared to 8 ohms, is an indication that it has good output current capability. In this case, the fact that the amplifier can put 250W into 8 ohms but only 400W into 4 ohms, is an indication that its output is being limited into 4 ohms by its output current capability, and therefore the peak volume levels it can produce accurately into a speaker which dips to 4 ohms will be less than for a more benign speaker load (everything else being equal). But as long as the output current capability of the amplifier is not exceeded (and keep in mind that we are presumably talking here about tonal balance at moderate volumes), and as long as the output impedance of the amplifier is low, no frequency response imbalance will result.

A notable exception to all of this would be amplifiers which have tube output stages and are output-transformerless, such as the Atmasphere's, which may have an output impedance in the vicinity of 4 ohms or more. That would definitely result in a tonal imbalance working into a speaker that is basically 4 ohms in the bass and 8 ohms in the treble (see Stereophile's impedance measurements on the Aerial 7B). I recall Tvad once mentioning that he had an Atmasphere at one point, and perhaps that is what prompted his comment.

Regards,
-- Al

I'm in total agreement with BlindJim. Often enough, it's not the gear but how it's setup.

I recall Tvad once mentioning that he had an Atmasphere at one point, and perhaps that is what prompted his comment.

Regards,
-- Al
Almarg (Answers)

No. Not in the case of the Aerial 7B loudspeakers.

For more info regarding the concept I am trying unsuccessfully to describe, I refer those interested to chapters 6 and 15 of Robert Harley's "The Complete Guide to High End Audio".

So, here you have a list of solutions to your problem from many intelligent and well intentioned contributors that includes:

Room treatments
Speaker set-up
Changing source components
Changing preamp
Changing amplifier
Changing wire

The truth is that the solution is likely a combination of the above.

Isn’t high end audio fun?!

Did you say Changing Wire or Changing Wife?

You know one letter could make all of the difference in sound quality! (LOL)

Only Kidding!

Thanks for the explanation Al, but I need to read up more about this subject, so I think I'm going to get Robert Harley's book and some others that I've heard about here, because I would certainly like to understand electrical impedance mismatches better.

Rich

I have several pairs of Aerials including the 7Bs. I've run a lot of different amps on the them. I found they sounded all sorts of different depending on the amp. I'm sensitive to highs in recorded music so it was an especially important point to me that they sound right. I also had a number of other speakers and can't say that the highs really change all that much from speaker to speaker. Also, the Aerials are so well built that's it's very easy to have them up too loud and that ends up being painful. I settled on McInitosh and also Bel Canto. You can't beat Mcintosh for smooth pleasing highs IME. I've got the 7Bs in the bedroom now running off Bel Canto's S500. The BC has stronger highs and dynamics than the McIntosh but I would say the highs sound good. Surely the room has something to do with it but if I were you I'd be in the market for a different amp. The Aerials absolutely sound different depending on the amp. I would even go so far as to say that in a blind test with the 8 or 10 amps I've tried with them I could dicern which amp was being used with them.