Excellent amplifier measurement method

[Ingenieur]

I've been in the hobby for almost 50 years, and an EE for 40. I've seen similar data formatted differently for industrial gear but not audio. Came across it while trying to find the rumble filter spec for my 509X.

Took me a minute to comprehend but it measures output V drop vs Z and phase.
Stability and linearity under a varying load like a speaker presents.

V at 8 Ohm and 0 deg is 35, 150 W.
It is constant for phase +/- 60 deg.

At 2 Ohm only droops to ~30 V (450 W)!
For the same phase variation.
At 4 Ohm ~32 V (250 W) for the same +/- 60 deg.

In other words, this amp is linear and stabile at ~ 32 +/- 2 V at any point for a load of 2-8 Ohm and +/- 60 deg.
+/- 60 degree is a power factor lead/lag of 0.5/0.5.

I know, geek alert.

 

[mhardy6647]

I thought that current audiophile standard was comment from one's significant other, from all the way out in the kitchen.
You know...

"It's never sounded that good before!"

(sorry... sorry!)

 

[Ingenieur]

I thought that current audiophile standard was comment from one's significant other, from all the way out in the kitchen.
You know...



(sorry... sorry!)

Only if they like the music...

 

[Ingenieur]

Another thing I just realized. Each one of those points is at 1% THD, ie, the amp is overloaded.
The 8 Ohm is at ~155 W or 35 V
Rated is 120 W, 31 V
My bet is at say 30 V there would be no droop/sag and THD <0.1 % THD for all points. That is 450 W at 2 Ohm.


From this curve (different source, but same values) at 2 Ohm <0.01 % at 450 W! Damn fine engineering imho.
From the text at 8 Ohm 155 W at 1%.
The graph in the first post, 35^2 / 8 ~ 153 W. Almost identical.

Stereophile measured 154 W/8 Ohm/1 % THD
CONSISTENCY

The sound? It has NO sound as far as I can discern.