You always get ringing - with feedback, with out it, with inductor or without. The cause is speaker cable capacitance, speaker cable inductance and the inductive output behaviour of the amplifier itself which causes Zo to increase with frequency.
Correct but this resistor is change sound signature and you need more time for selecting him between many suppliers 🙂)
China resistors is not good for sound.
I use Soviet Union resistors or Vishay for this.
USSR resistors is more warm in sound (photo in attachment) date of manufacture this about 1992 year (latest parts) I buy all about 1000qty
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Correct because if you do not use this you have untability in all power amp system
I watch this in my oscilloscope🙂)
Good day
Dear Nelson could you ask about Naim amps
What you think about this?
Old amps 110, 160, 250 or new?
Also Naim amps is not use of output L and R circuits what you think about this ?
Dear all, it’s good to see any action on a thread you started but I am still interested in responses to my original query which, I guess in another form is, what will the amp “see” when it’s connected to the autoformer and does this include an amount of inductance that is traditionally provided by using Naims own speaker cables.
BTW the Behringer amp works perfectly but has extremely noisy fans and is physically too big. Also, years ago I worked in commercial sound installation using these particular autoformers and they were connected to all types of amps without problem (unsure of Naim amps of course).
Best from sp
BTW the Behringer amp works perfectly but has extremely noisy fans and is physically too big. Also, years ago I worked in commercial sound installation using these particular autoformers and they were connected to all types of amps without problem (unsure of Naim amps of course).
Best from sp
The spreading inductance of an autotransformer should be far above the inductance of a cable of a few metres (unless you use it as a 1:1 autotransformer, but that would be a bit silly anyway).
No wise person will give you a definite answer. That switch-panel is a real mystery item. And the actual need (if any) of the NAIM for output padding seems to be unclear.
Without detailed information: the autotransformer input WILL be some inductance and some capacitance. Probably enough capacitance to distress some amplifiers.
You just want background music? Try 10 Ohms 10 Watts in series with the amplifier output terminal. They the worse-case impedance the amp can see is 10 Ohms, which is more than safe. Maximum loudness may be less than half, but we know most home hi-fi runs less than 1/10th max loudness unless user is drunk/stoned.
For the folks who want the math behind the issue and don't already know:
https://www.hifisystemcomponents.com/downloads/articles/Prevent-Emitter-Follower-Oscillation.pdf
Of course, almost every transistor based gain stage in an audio circuit is an emitter follower, if you count Re and any emitter resistor as a "load."
Just as a point of interest... You can simulate this all pretty easily in SPICE. You just need to look at the input voltage at the base of a stage using the AC analysis. At some frequency - maybe 10's or more MHz - the input voltage will rise above what you'd expect based on the input stimulus. That's where the conditions described in the Chessman and Sokal paper suggest that the input resistance of the device becomes negative. At the output the voltage gain rises above unity, which should never happen in a follower. Peaking, ringing, and all sorts of fun stuff happen then.
https://www.hifisystemcomponents.com/downloads/articles/Prevent-Emitter-Follower-Oscillation.pdf
Of course, almost every transistor based gain stage in an audio circuit is an emitter follower, if you count Re and any emitter resistor as a "load."
Just as a point of interest... You can simulate this all pretty easily in SPICE. You just need to look at the input voltage at the base of a stage using the AC analysis. At some frequency - maybe 10's or more MHz - the input voltage will rise above what you'd expect based on the input stimulus. That's where the conditions described in the Chessman and Sokal paper suggest that the input resistance of the device becomes negative. At the output the voltage gain rises above unity, which should never happen in a follower. Peaking, ringing, and all sorts of fun stuff happen then.