Re: Here you have what some amplifiers may deserve
This is the better abush test that i have seen in my life! And not only for amplifiers!
Nero had used this abush test on ancient Rome because he had reasonable suspicions for the durability of his capital. And finally he was fully justified in his suspicions.
Oh! this Carlos, strikes again
destroyer X said:
This is the better abush test that i have seen in my life! And not only for amplifiers!
Nero had used this abush test on ancient Rome because he had reasonable suspicions for the durability of his capital. And finally he was fully justified in his suspicions.
Oh! this Carlos, strikes again
carlos my man .....
sometimes i think i want to kiss you !!!! a friendly kiss that will sound like big smaaaaaaats
i see that even when you disagree with this or that issue you always put in a polite and friendly way .......
also even if you disagree with that issue you will always add an opinion that will be usefull in the future or said in order to make the amp better ......always in a polite and friendly way .....
thanks man its simply the minimum i can say
sometimes i think i want to kiss you !!!! a friendly kiss that will sound like big smaaaaaaats
i see that even when you disagree with this or that issue you always put in a polite and friendly way .......
also even if you disagree with that issue you will always add an opinion that will be usefull in the future or said in order to make the amp better ......always in a polite and friendly way .....
thanks man its simply the minimum i can say
The venerable NAD 3020, when first demo'ed at a consumer electronics show, was driving (IIRC) no less than EIGHT pairs of speakers (8 ohm a pair) simultaneously, and evidently did so without a hitch.
I am told that part of each 3020's burn in test was to crank it to full volume, with signal applied, and deliberately short the speaker terminals. The amp had to survive a certain amount of time this way, and they have NO output relay, and NO protection circuit. The only things there for severe overload were a thermal breaker just past each pair of output transistors, and the main power fuses (slo-blo even).
For those wondering "how?", here's where part of Mr. Edvardsen's genius comes through: The power supply he designed for the 3020 was more than enough to satisfy the needs of a 20 Watt per channel amp, but given the output transistors he chose, the SOAR was so high that the transformer and power supply caps together could not push enough current (instantly) through the output transistors to destroy them, unless they had some kind of defect. So, by the time things heated up enough to be dangerous, either the thermal breaker would trip, or the fuse would blow.
I am told that part of each 3020's burn in test was to crank it to full volume, with signal applied, and deliberately short the speaker terminals. The amp had to survive a certain amount of time this way, and they have NO output relay, and NO protection circuit. The only things there for severe overload were a thermal breaker just past each pair of output transistors, and the main power fuses (slo-blo even).
For those wondering "how?", here's where part of Mr. Edvardsen's genius comes through: The power supply he designed for the 3020 was more than enough to satisfy the needs of a 20 Watt per channel amp, but given the output transistors he chose, the SOAR was so high that the transformer and power supply caps together could not push enough current (instantly) through the output transistors to destroy them, unless they had some kind of defect. So, by the time things heated up enough to be dangerous, either the thermal breaker would trip, or the fuse would blow.
SY said:
Not been my experience at all. All the ones I've ever worked on were either mods, recaps, or replacing that %$#@%$ power switch. Mind you, I'm referring to the very first version, the 3020 Series 20, no one has ever brought me a 3020A, 3020B, 3020e, or 3020i. If I remember correctly, there was a bit of screwing around with driver transistors as they evolved.
Then, the last iteration, the 3220PE, a 3020 with the evil power envelope circuit
.Worked on a couple of those! Pretty much told people, if you let me rip this out when I rebuild it, I can pretty much promise you it will not blow up again.
Don Taylor
BrassTeacher said:
Yes, i had a 3020 before 17 years. I remembered very well the pair of TO3 transistors per channel but i think this amplifier had also a soft limit circuit activated by depressing a switch on the backplate. Am i right?
Anyway the ruggedness of this amplifier was indeed proverbial.
Some US constructors of P.A. amplifiers used also the burst test (if i remembered well) of the 24h continuous operation of each device under 4Ù load at 50 to 80%?? of full output power with a sweep signal of 20Hz-20KHz.
These all during the old good days.
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