Resistors vs.peltz Autoformer- Differences

gdnrbob OP3,025 posts
01-31-2020 9:05am
@georgehifi .
That isn’t what this thread is about.
I just wanted a clear explanation of what these 2 devices are doing.
Ralph and Almarg provided that.
Bob

I understand that’s all "you" wanted to know, but it’s the smoke screen that’s given here about autoformers/resistors that are in series or parallel that causes me to post, as it gives "others" the wrong idea that the use of them is going to solve a problem without any negatives, which is wrong!!

As I said the best is to have the right amp or speaker for the right speaker or amp, without using band-aid fixes that add other problems..

Cheers George

gdnrbob OP
Both seem to allow the amp to perform 'better',

Wrong.
https://forum.audiogon.com/discussions/resistors-vs-peltz-autoformer-differences/post?postid=1874053...

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

Look all, to prove it to yourselves that Zero's are a band-aid fix, just put a pair on an amp and speaker that have NO problems with each other and hear what happens, SOUND QUALITY TAKES A BIG HIT!
We've done the experiment at our audio society meeting, and it was 100% unanimous, that the Autoformer is a baind-aid for a problem that should be fixed at the source with different speaker or amp.
Cheers George

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

Given that Zu has signed off on the resistors, I would imagine they find any tonal differences to not be significant.

The only way I could see that working, is if the speaker was purposely over damped in it’s design, and all you do with the resistors is to ruin the damping factor (output impedance) of the amp so then bass is then becomes correctly damped (to suit the room maybe)? Whatever it is, it’s a wank, so are Autoformers, just get the right speaker or amp to do the job properly. 

Cheers George

Resistors vs. Paul Speltz Autoformers- Differences?

Both band-aid fixes, get the right amp to do the job in the first place and you'll be sonically much better off.
If you can't bear to change that amp that can't do the job, then change the speakers so it can.

Cheers George