...with feedback.
Please measure FR curve at 5W, and distortion at for example at 30-40Hz.
Yes, i agree.
Simulation can be helpfull, but only if proved in praxis.
It's like autonom driving, in theory everything works.....
But please, no more porridge. ThanX.
For me Nelson Pass is the right way, if he told the first Watt is the important one. And with feedback you can reduce something but not everything. Better there is no need for feedback.
I'm confused.
Earlier you rejected the Skunkie mods out of hand, at least in part because they employ feedback.
Later, you say you're using her feedback scheme.
Now you say no feedback would be better. OK. No need for feedback would mean running either triode output tubes or triode strapped pentodes. Yet, earlier, you said you weren't interested in sims of the amp in triode mode. So you seem to have rejected that idea, too.
Running in triode will result in less power, of course. But since you have very sensitive speakers and also support the notion that the "first watt" is the most important, having less power shouldn't be a concern.
So I'm puzzled by your lack of interest in triode mode which, arguably, would produce the best quality "first watt" without using feedback.
Isn't that exactly what you're trying to accomplish??
Oh no doubt at low frequency they aren't doing this well and we all know that. I was measuring this distortion curve at 1Khz, but the amp as delivered passed 1% distortion at 0.05W using the same 1Khz test. So much for a "good first watt" lol. I ended up with 2W at less distortion than the stock amp had at 0.05W, which I would hope most people would see as an improvement.
My mods are a huge improvement over an otherwise horrible sounding amplifier. And no, it's never going to equal an amplifier that uses output transformers that one of them costs more than this whole amp does. 🙂 It did turn out to be a very decent sounding amplifier after these mods for a less than $500 tube amp.
No no, you somehow misunderstood me, i will not have and i'm not using any feedback.
I will only change the operating points of in- and output tubes . No less, no more.
A lot of people use tube rolling for changing something. This is, changing operating points.
HiYa Stephe,
there are different ways to improve this one. I did some tube rolling, and yes, now it got some better. But this is an expensive way to go. There have to be reasons, and this i'm looking for.
My first impression with my La Scala was not bad, but after some time i was missing only a little bit of something...
OK, I guess I must have misunderstood your earlier post. Perhaps there is a language issue.
I understand that you want to experiment with operating points on the input tubes. But I was asking about the output tubes, not the inputs.
Any response to the rest of my post?
Pentodes, when operated without any feedback, are not linear. You may be able to drive them better using different operating points for the input tubes, but that will not make them linear.
Why don't you simply run the output tubes in triode?