Resistors vs.peltz Autoformer- Differences

@georgehifi ,
As I said before, I agree.
I only posted this to get an idea of what is being done and the differences between the Zu resistor and the Spetz Autoformers in terms of how they are operating.
I don't know a lot about such things, and wrote some things that were improperly stated and only rectified when I provided a link to the Zu webpage.
My main concern is: what is the difference between adding a resistor to a speaker vs. the Speltz autoformer? 
Bob

@gdnrbob what's your amp BTW? OTLs by any chance

My main concern is: what is the difference between adding a resistor to a speaker vs. the Speltz autoformer?

@gdnrbob   In your case would the resistor be placed in parallel (across the speaker or amplifier terminals)? If yes, then obviously the resistor is a lot cheaper. Since this is something ZU is recommending for use with their speakers, I would not regard it as a 'band aid' fix as George suggests. ZUs are easy to drive and you don't need an amplifier with high 'current'; in fact they seem to sound better when the amp has a fairly high output impedance.


You'd have to try the ZEROs to see if its worthwhile, but since this is a method suggested by ZU I don't think the ZEROs are worth consideration.

No matter how you look at it, resistor "parallel", with the amp terminals makes the amp work harder, and have more distortion, run hotter, will go out of it’s Class-A bias earlier and sound maybe harder.

If the resistor is in series then you screw up the damping factor (raise the output impedance) of the amp, so the bass is less controlled and muddled, (unless the speaker was purposely over damped design which I doubt).

As for the Autoformers, just an "expensive band-aid fix" to solve the problem of a bad match between amp and speaker, just get the right amp or speaker to do the job properly.

Cheers George

@luisma, @atmasphere ,
I have no desire to add resistors or the autoformer to my speakers.
I was just curious as to the differences between the two methods with regards to how it affects an amps performance, as well as the resulting sound performance of a speaker.
Does this make sense? I'm probably using the wrong words but hopefully you get my drift.
Both seem to allow the amp to perform 'better', but does the resultant speaker sound change with either method?
B