Pure Class A if you please...
- 50 posts total
- 50 posts total
6 watts is quite a lot of class A power. Given that most decently recorded music has a peak:average ratio of ~ 10 or more, that means that peaks would be 60 watts if you were, on average running in class A.
And 6W is a lot of power! (surprisingly). As a designer i put a lot of experimental (read that: could blow up) stuff in my system with very expensive speakers. So i have fused adapters pretty much all the time. I use 1A fuses. Which means that they blow > 8W. They never blow.
that in an RMS sense… it is mostly Class-A.
I think you mean in an **average** sense. RMS has to do with how we measure a wave: peak, average, or "area under the curve" (root mean square or RMS). It is quite different. For a sine wave RMS = average. For complex waveforms you need to integrate to get the area. Eek! calculus!
But your point, if i infer right, remains valid.
The Threshold S550e amp from the early 90's was rated at 250 WPC.
This stasis design had optical bias circuitry and the bias was set at 100mV.
Threshold claimed that it would run up to 20% of it's rated power in class A (that's 50 watts!!)
My NAK PA-7A MKII is also a stasis design but without the optical bias circuit of the S550e of the same era.
Bias specs for the NAK is 40mV but I run it at 50mV. It draws around 200 watts at idle. It's rated at 225 WPC.
My guesstimate is that it runs in Class A for the first 10-12 watts.
Geez i fell like a detective, and with that data inspector Clouseau to be specific.....
per the threshold - complete the math!! 100mV across what? What's the derived current (which is what matters)? Across the emitter resistors, which are what value? Without that you don't know the current. Let's assume 1 ohm. We shall assume per device, but number of parallel devices unspecified. If nelson claimed it was A to 50 watts, that's 20V/8ohms or 2.5A; which implies 25 parallel NPN and 25 more parallel PNPs per channel -- minimum. Some number there does not add up.