I propose the test: to build 2 amps, one on transistors where such dynamic in nature effects (including other dynamic effects) intrinsic to the devices used exists, another on tubes where devices themselves don't have such effects, but topologies often do, such a way that dynamic distortion affect are minimized, then compare sonically. Both amps should have 20-20,000 Hz bandwidth, the same max output power, the same THD. Tube amp would sound more natural. And only explanation why it sounds more natural I see, is absence of dynamic in nature distortions.
Yes!
Also, when thermal stabilization over-compensates it gets unstable. Quiescent current not only goes above and below optimal bias with delay after envelope. It starts oscillating!
OK, ok..John, So I just ordered a slightly used z.3 This gives me another contemporary amp to test my ideas on. I have three or four things to use it on. I hope it is as good as the critics suggest. If, I'll buy more of them.
I gave the measurement I made last year some thought. What I am seeing is the mechanical delay from the driver at rest. I doubt this is what my wife is hearing. But, I would have guessed the higher the DF, the less lag and time to catch up but that did not correlate with the measured DF of the amps, 10, 60 and 200 respectively. The Rotel at 60 was the best. I have been plotting a set of tests to determine if it is a fundamental or harmonic problem. Even warned her.
So, next round will be the Parasound z.3, Rotel RA-840 BX, Creek 4330, and restored Hafler DH-120.
I gave the measurement I made last year some thought. What I am seeing is the mechanical delay from the driver at rest. I doubt this is what my wife is hearing. But, I would have guessed the higher the DF, the less lag and time to catch up but that did not correlate with the measured DF of the amps, 10, 60 and 200 respectively. The Rotel at 60 was the best. I have been plotting a set of tests to determine if it is a fundamental or harmonic problem. Even warned her.
So, next round will be the Parasound z.3, Rotel RA-840 BX, Creek 4330, and restored Hafler DH-120.
Then Self is wrong about this issue as well as other issues.
Let's invite him here to discuss, where he was right, and where he was wrong. The main problem why he promotes wrong views I see, he isolates himself from discussions that question his beliefs. While he is not here, I strongly advise to keep such arguments of personal character as far as possible from technical discussions.
Now we are talking power devices. How about if this device was biased in class A? It would be not intuitive that the signal would cause significant variation as on average, it is a small proportion of the overall current.
I originally brought this subject up, because it has been my belief after years of listening to different SS topologies, that thermal tracking/ transient distortion is an issue. On a/ab amplfiers running below 4 ohms you can hear it subjectively( i have never measured) not as easy to pickup at 8ohm's. I hear it on slow transients , not fast, (strike of a piano key softly not hard) If you allow the amp to cool , it goes away, i don't hear it on class-a amps nor class-d. Both of these amps run at the temperature extreme's for amplifiers.
It would be interesting to hear from those who have the knowledge and equipment to test such happenings.
No , because the temperature is more constant , due to the bias.....I did try John's Halo line, give one a try. We never noticed it on the one we had here, the protect relay would intervene , maybe before this was noticable.
Hi,
The commentary would interest me, but not much, the rest i already have.
Actually, D. Self makes CLAIMS about this and then presents Spice Simulations, but fails to show actual data.
Honestly, the thermal delay in plastic transistors is low enough to observe the thermal effects quite well, if your observation equipment is blessed with a sufficiently fast response.
Ciao T
The commentary would interest me, but not much, the rest i already have.
Actually, D. Self makes CLAIMS about this and then presents Spice Simulations, but fails to show actual data.
Honestly, the thermal delay in plastic transistors is low enough to observe the thermal effects quite well, if your observation equipment is blessed with a sufficiently fast response.
Ciao T
Wayne, I am sorry that you had a problem with the protect relay. Usually that says that: You were oscillating, had an output voltage offset, or over-temp due to bias adjustment. I took an older unit in last week to Parasound, an HCA-1206, for output voltage offset. (servo failure) I have had it happen with my own units, BUT only under severe running conditions OR heat-sink blockage. For a commercial product, like Parasound, an output protection relay is MANDATORY to keep your speakers from destruction, if the amp fails seriously. However I do not design the protection circuits, and they change over the years.
Actually, there's quite a bit of data in that series of papers which clearly show the absence of the predicted rise in LF distortion. Unless the "Audio Precision" logo is some sort of spice simulator with which I'm unfamiliar.
John,
No worries the amp was an A21 driving an low imp ribbon hybrid and we originally wanted the JC-1 for that speaker, there were no issues when playing the 4 ohm Finals ESL's, but only on the ribbons, where it would shut down after 10 mins , so we moved it to drive the subwoofers.
I had spoken to you before and you had suggested the JC-1 but the dealer did not have any and they thought the A21 would work enuff for the demo.
No worries the amp was an A21 driving an low imp ribbon hybrid and we originally wanted the JC-1 for that speaker, there were no issues when playing the 4 ohm Finals ESL's, but only on the ribbons, where it would shut down after 10 mins , so we moved it to drive the subwoofers.
I had spoken to you before and you had suggested the JC-1 but the dealer did not have any and they thought the A21 would work enuff for the demo.
We got carried away after seeing this :
Its clipping power increased by 0.3dB into 8 ohms, reaching 586.5W at 1% THD (27.7dBW, fig.7, black trace), with 1154W available into 4 ohms (27.6dBW, blue), 2255W into 2 ohms (27.5W, green), and no less than 4.2kW into 1 ohm (27.2dBW, magenta). The latter is equivalent to an output current of 64.7A!
-Stereophile JC-1...
Its clipping power increased by 0.3dB into 8 ohms, reaching 586.5W at 1% THD (27.7dBW, fig.7, black trace), with 1154W available into 4 ohms (27.6dBW, blue), 2255W into 2 ohms (27.5W, green), and no less than 4.2kW into 1 ohm (27.2dBW, magenta). The latter is equivalent to an output current of 64.7A!
-Stereophile JC-1...
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