N said:
What is a reasonable testing regime for each of the following cases, in
terms of driving with continuous sine wave, what frequency and what
percentage of power in the load to represent in service use ie rather than
continuous sine, for
Bass amps
200 Watt rating, %, f
400W,%,f
600W, %,f
Guitar Amps
200W rating,%,f
400W,%,f
600W,%,f
And overall duration of such testing ?
I use 100Hz for bass and 400 Hz for guitar amps and 1 hour duration but I'm
concerned about what sine to in-use equivalent percentage I'm using
a/ to accurately represent periodic in-use signal rather than the more
stressing continuous signal .
b/ under or overstretching the amp
Wow, there is a lot to this, and no one method is going to fit all cases.
The average amp tech just needs to confirm factory specs through final bench and play testing.
NOTHING MORE.
Now, STRESS testing is a totally different story.
The types and methods of stress testing varies due to the specific goals such testing is to
provide.
You can subject an amplifier to a multitude of all manner of stress testing. Vibration, electrical,
thermal, environmental, physical pressure, etc... to find the most likely trigger for any future
possible failure event.
If the major amp manufacturers did 1/10th of what I had just mention here, with some freaking
integrity behind it, you would NOT have as many Polished Turds on the market.
Yes, you could put improved reliability, service life, and quality in cheap products without them
being Polished Turds.
THAT, can be done. But isn't.
Because, there is no money in it if they last too long.
It's no longer a cheap short term disposable product.
<after thought>
I'm old school. That was the way I was raised.
If the speedo on the dash board says 120 mph, I expect the car to do it.
So, I head out to the highway late at night, and I put my foot on the floor.
Yes, a 1962 Corvette has a 160 mph speedo, and I put my foot on the floor.
That's when I found the body rises up, and gets light at about 115 mph.
Which, forced me to back it down. The 65 Stingray next to me didn't have that problem, and could
safely reach higher speeds by its non air plane wing body design.
Now, how would I know that the 62 body design functions as an airplane wing at 115 mph if I had not
tested, and found that to happen.
The only way to find out what is really in front of you, is to test for the LIMITS, and find out
first hand what they are.
I test EVERYTHING unknown to me THAT way.
Including vacuum tubes, and amplifiers.
From EL-84's to KT-88's..... beat 'em till they quit. Then, you know what ya can or can't depend on
at different levels of operation.
Then, knowing the limits of the tubes placed in an amp to be stress tested, you KNOW you are
starting out with tubes that can take a beating, and are NOT likely to trigger a failure even on
their own.
When it comes to tires, I get the best performance tire available.
With vacuum tubes, it's the same way.
All quality high performance items have their price.
For those outside of that life style, polished turds are fine.
Especially, when you never have to put your foot on the floor.
Regards,
Rich Koerner,
Time Electronics.
http://www.timeelect.com
Specialists in Live Sound FOH Engineering,
Music & Studio Production,
Vintage Instruments, and Tube Amplifiers
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