Home Propeller Head Plaza

Technical and scientific discussion of amps, cables and other topics.

[ Follow Ups ] Thread: [ Display  All  Email ] [ Propeller Head Plaza ]
[ Alert Moderator ]

both replys

Hi Tubeguy, Thoriated

Both kinds of amps can be good or bad, personally I like tubes, they have some important “good” features. In other posts I have made I have highlighted a few things wrong with some SS design approaches but admittedly, that was another thread so you wouldn’t have known that.
Let me explain, I am keenly interested in making things sound real.
For the last 25 years my job has been designing acoustic transducers and in the last 10 years full range speaker systems and I have been fortunate to have had a good deal of soa test equipment to use.
Here is a review of a new design.
An old bio fwiw: http://www.prosoundweb.com/chat_psw/bios/danley_bio.shtml
I have a new company the last 2 years, Danleysoundlabs.com

The Time Delay Spectrometry system has been especially useful for developing new loudspeaker drivers.
My point, if there were anything “hiding” one form of measurement or another would have shown "something". With the TDS system, things which are detectable by ear are usually large in one domain (time, energy, frequency) or another.
When you say today’s accepted measurement’s don’t reflect what you hear, it is true, but there not suppose to either, magazines taught consumers that.
A measurement is just that a measure of some thing, not a judgement.
When you need a 2x4 that is 93 ½ half inches long, you either cut it where it looks about right or you measure with a ruler and mark it, judge or measure.

The null test is a fundamental principal in electronics and reveals any additions or subtractions to a signal. The way I describe is the subjective, audible output version, you hear the difference signal.
It would seem that if the input is exactly the same as the output driving a real speaker as a load, except the output is 20dB larger, the amplifier can’t be doing anything bad or good can it?. I mean, if the signal is going to the speaker has what ever it is, it has to be there right? It is then a matter of comparing what comes out to what goes in to see what the difference is.
Thoriated, the GD in band of modern electronics is insignificant.
It might not be at the low end “if” the low response doesn’t extend far enough down. Then, the amplifier would have significant GD down low, but the test could still be done by limiting the LF content.

In the case where the desirable sounding amplifier has significantly more residual signal in a null test, one can be sure the amplifier is making up all that “goodness” and not the musical instruments or musicians. Nice to hear or not, it is not accuracy you hear.
A problem that could make some amplifiers that have a high output impedance test unduly worse is that the speakers impedance curve will alter the current drawn and then change the Voltage and response curve. One could also argue this feature is undesirable as what you get from the amp depends too much on the speaker its connected to.
Fwiw, this test works on speaker cables too, you hear the difference from one end to the other.
Best,

Tom Danley



This post is made possible by the generous support of people like you and our sponsors:
  VH Audio  

Follow Ups Full Thread
You can not post to an archived thread.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2025, Audio Asylum, all rights reserved ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]