Yup, and because you essentially had the basis of something good to work with, the finished product turned out really well :)
Marco.
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Yup, and because you essentially had the basis of something good to work with, the finished product turned out really well :)
Marco.
Here I am late to the party yet again!
I want to drop back to the talk about Rise Time and Slew Rate. I didn’t read where anyone gave an accurate description of them. So here’s my two cents.
Both of these measurements are not so much about the output stage, as how you feed the output stage. And why two amps, both claiming the same watts, and even having the same output transistor compliment, sound different. (I won’t comment on tubed gear, not my area)
Rise Time is how long it takes to bring the output up to spec, so when a sudden transient happens, how quickly can it be ready for the next one.
While Slew Rate measures the decay, how able is the amp to maintain a transient. A sharp pop of a snare drum, the amp delivers the specified power to the speaker, but it can’t keep it up forever, the voltage drops off over time. An amp that claims 25V/us, is a very good amp. Meaning, after the transient, the amp is unable to keep up, it loses 25 volts per microsecond. And another 25 volts every microsecond after that, until it runs out of power. Compared to an amp that claims 150V/us, this can make a very audible difference! The snare pop dives off much faster in the second amp, smearing the decay, then Rise Time brings the output back to full potential before the next one. A slow rise time can cause subsequent drum whacks to be Lower than the one before, if it isn’t rising fast enough to keep up. Both are more about the power supply, the capacitive storage for the output stage, and why two amps that both claim 100wpc can perform extremely different.
If you want a good tube amp, buy it by the weight! The heaviest one has the biggest transformers. I’m not sure the exact correlation between amps and weight, but the amp I own now is the heaviest one I’ve ever owned, and the best sounding. Just lucky maybe?
Russell
I think on the whole, Russell gave quite a good insight into what is going on, although by his own admision, his wording may be a bit misleading to the tech savvy here,[ I am sure I, and others here have been guilty on that score at times too] Its a matter of getting the balance right when trying to get your point accross to those who may not be paticularly technicaly minded, but know what they hear, Sometimes people can get turned off a subject they may otherwise find interesting, if things get too technical.:)
Both are defined mathematically.
Andrew defines slew rate accurately, and rise time is defined as being the time taken for the response time to go from 10% to 90% of the total step change.
What it says on that Wikipedia page, if you scroll down under the word Definition, (I tried to copy and paste but it wouldn’t act right) is exactly what I am trying to say, a measurement of change over time, and when that is referring to the output of an amp, the output does not resemble the input, just as the illustration of the square wave being skewed, this is all I am trying to get across, just as described on this Wikipedia page. The larger the number, the greater the deformation of the waveform, so bigger is not better, at least when talking about the output of an amp.
Apparently it can mean many things when talking about the Slew between stages, or involving digital circuits, I am not referring to those situations.
Russell
Makes perfect sense.