Mr Simon, with your height I'd assume it must also have included a sticking wall at the end of the floor.
"magic smoke by burning up any output Zobel", "they are seldom(never) rated for continuous full amp power"
You know, even the Zobel needs real engineering design and not only arm chair considerations or lowest cost design.
Let mi give you a real example. My Zobel R-C's are 10R/2W+33nF or 10R/2W+15nF. Let's take the 10R/2W+33nF, the worse case. Please see attached measurement at the amplifier output with 65Vpp voltage swing, 8R load and the Zobel mentioned. Also please see the voltage, current and power analysis over the resistor 10R. You will see that it dissipates just a little above 2W, so there is no smoke during the test and there is no smoke even during the short-time clipping test.
The true is that many amplifiers use the deadly 10R/0.6W+100nF Zobel, which is a poor design practice. But, most of the problems is often in cross-conduction above 20kHz, many amplifiers are even not able to pass 20kHz test at full output swing. There is no excuse for such amp behavior, at least to me.
Attachments
R.Cordell, tells us that a distributed Zobel may be better than a lumped version at the final output.
A final 10r+100nF, could become a 30r+33nF at each device pair of a 3pair output device.
That allows one to place the Zobel where it is needed, in a close loop around the output devices and local decoupling and allows one to place adequate power dissipation capability that survives all music and audio reproduction.
A test signal @ 100kHz is not an audio signal.
A test signal of 20kHz sqw is anot an audio signal.
Both will cause increased heat in the Zobel, not just the resistor, the esr of the cap will also generate heat.
Look at the de-rating required for high frequency signals.
A final 10r+100nF, could become a 30r+33nF at each device pair of a 3pair output device.
That allows one to place the Zobel where it is needed, in a close loop around the output devices and local decoupling and allows one to place adequate power dissipation capability that survives all music and audio reproduction.
A test signal @ 100kHz is not an audio signal.
A test signal of 20kHz sqw is anot an audio signal.
Both will cause increased heat in the Zobel, not just the resistor, the esr of the cap will also generate heat.
Look at the de-rating required for high frequency signals.
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Which makes this post:
http://www.diyaudio.com/forums/lounge/146693-john-curls-blowtorch-preamplifier-part-ii-7680.html#post4551555
Either hearsay, a fantasy or an outright lie.
Nice job of cutting yourself off at the knees, old man!
Good catch, it is not an audio signal. But if you make it working with 100kHz and same time you use an input RC filter, any doubts about behavior with HF digital garbage are excluded.
The Zobel cap is to be high dv/dt type.
Look, I do not argue, I just do it.
Agreed, given that most people listen to audio composed of speech, music, and EFX, and compounded by the fact that most listen to digital sources sampled at 44 or 48 KHz.
Pavel, your above message brings back many fond memories of the man who once gave me a lecture on zobels some 30+ years ago. He absolutely insisted on the fact that any single resistor rated up to 2W will not do, it had to two in parallel. That way you doubled the power handling, and at the same time improved thermal behavior by doubling the cooling area. The cap used absolutely had to be a high quality polyprpylene, and again, preferably two in parallel to share the work. He wouldn't stop until he was convinced I learnt that for all time - and he was right, ever since then I used two and two in parallel. Sure, it costs more money, it uses more PCB real estate, but it makes for a zobel you put in once and don't ever have to think about it again. The older I am the more I think of him, he passed away last year and by sheer luck, I saw him just one day before his heart conked out.
He always liked to say that the cheapest was to do things was the right way from the start.
He always liked to say that the cheapest was to do things was the right way from the start.
Dejan, he was right, however we have to speak about capacitance as well. With 15nF, 33nF and 100nF the power dissipated in the resistors differs, in case of the same voltage swing. I know this is obvious, but we always need to know resistance, capacitance, voltage swing and maximum frequency. Then we can calculate dissipated power and max. dv/dt and make a right choice of components, which is always possible, rather than excuses and recommendations to de-solder the Zobel before testing 
You really have a problem with comprehension. I suspect the cause of it indicates the need for counseling or treatment. Seriously.
Quite so, Pavel, one of the few nice things I have to say about myself is that I understood how lucky to have him for an informal teacher even then, so I actually took notes. He's the only person I know who designed and produced a 3 kW pure class A amplifier. In fact, it was a gigantic hetasink with so many power devices bolted to it that it would have made Motorola weep of joy (he used what he had way back then, the Motorola MJ 15xxx 250W TO-3 devices). It weighed over 100 kilos, 99 of which were heatsinks. He had to use heavy duty industrial sockets.
He had to use heavy duty industrial sockets.
Simon, you seem rather unschooled in the area of diagnosing mental infirmities.
There are well known indications of them - unhappiness, lack of success in education and professionally, inability to form stable, long term relationships, etc. You can look them up on the web.
You are obviously unhappy and caught in the act of lashing out irrationally at someone that you perceive has made you unhappy. All I did is catch you in a few little fibs.
I'd bet that if we compared life's stories you'd come out no better than second.
If I were you, I'd stick to amplifiers or better yet, your day job.
Funny I read this as a description of you and your behavior on these threads.
Fibs? No you are imaging things.
As to comparing life stories, it shines through that you are really unhappy. Why you think I am is a mystery.
You constantly pick on folks, have a lack of understanding of what seems to me to be basic issues.
As to mental issues, your reference to the web for insight is really funny. I'll stick to my distinguished friends for any insights there.
As to coming in second between the two of us I suspect you would be fifth.
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Bill,
I though you were ignoring the troll. I am having fun drawing him out. He really is clueless.
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