What does "8 Ohm Compatible" mean?

[DirtyErnie]

'83, yeah, it definitely is more of a guitar amplifier thing.  In a home hifi sense, I kinda see it as some sort of gimmick. Sure, you can do it, and you'll likely not have any problems, but that doesn't make it a good idea.  Ultimately, it's your ears and your gear:  season to taste.

The amp mentioned in the forum post above and my response to it seems to be running EL84's at somewhere around 600V (judging by idle current and dissipation mentioned by the designer).  That's territory few dare to tread.  I might be willing to push an EL34 or 6L6 that hard with ~300v screens, but never anything on a 9A base.
There's certainly a lot more headroom with HiFi, and that allows 'getting away with' stuff that would let the smoke out of a guitar amplifier in a proper hurry.   

[CWelsh]

I think I may have found part of an answer in a Stereophile review from 2019.

 

"I found that the speaker's impedance magnitude (fig.1, solid trace) dropped below 6 ohms only in the upper bass and in the valley between the twin low-frequency peaks that define the reflex woofer loading. The minimum value is 3.65 ohms at 125Hz. However, the electrical phase angle (dotted trace) is sometimes extreme, and there is a current-hungry combination of 5 ohms and –49° phase angle at 90Hz. Despite its high sensitivity, the Forte III will work best with amplifiers that are comfortable driving 4-ohm loads. And the very large difference between the average impedance in the lower midrange and that in the treble means that the speaker might sound a touch bright with tube amplifiers having high output impedances."

 

I was pretty sure I had read somewhere that the impedance dropped down below 4 ohms at some points. This may explain why the bass sounded tighter with the Fisher vs. the ACA.

[82 Cornwalls]

Very few of the amps I have owned had multiple taps, the 3 I have now only have one pair of outputs. In this situation you just have to hook things up and see how well they get along. I don't push my amps and have never had a problem.

As far as speaker loading is concerned I'm sure over the decades there have been a lot of less than idea parings and yet somehow the equipment kept playing and the owners were blissfully enjoying the music.

 

Roger Modjeski (RAM Labs/Music Reference) often had his own way of doing things and they worked for him; never saw many customers complain either.

 

Thank you for your replies DE.

 

 

[82 Cornwalls]

With speakers like yours the power supply becomes very important and whether it is because of a particular design not being up to the task or because of tired parts the speakers will not be able to show their true potential.