Resistors vs.peltz Autoformer- Differences

In the context of this thread, George's comments don't add up. I have to assume that he didn't read everything here including the link.

The use of paralleled resistors by ZU has nothing to do with the speaker being overdamped. Its has to do with the fact that the drivers are typically 10-12 ohms which is an impedance that isn't matched well by some output transformers. In some cases this makes a difference with the amp, in other cases not so much, but the resistors are there to push the impedance down to a point where the 8 ohm tap (in some cases) will be appropriate. Our amps work fine with the ZU speakers and no resistors (or ZEROs) needed.

Depending on the number of drivers used in the speakers the resistors and taps on the amp will vary so as per usual, simply check with the manufacturers involved.

atmasphere In the context of this thread, George’s comments don’t add up

Sorry but I have to assume that "you" didn’t read everything

almarg

While using a resistor "will lighten the load on the amp" 
Also, damping factor will be affected very differently in the two cases

gdnrbob They offer resistors for their speakers that will lower/raise impedance

"They offer resistors for their speakers to Lower/Raise the impedance of the speaker" as seen by the amp

To raise the impedance of the speaker it would have to be a series resistor

My answer was in conformation to al’s answer, with the assumption that there was a series resistor involved, hence damping factor (output impedance) would be effected.

gdnrbob
As for any of this, getting the right amp to do the job is better than any of these "band-aid fixes", one of which is expensive and is only an interim fix.
Or change the speaker so that "wrong amp" then becomes the "right amp".
I’ve seen too many of my customers go down this "band-aid" fix route to "make" things work when they naturally don’t, and it always ends in disappointment.

Cheers George

@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.