Flat earthing again?
What, like Lynn Olson? A1 15 watts at 0.3% distortion, and A2 30 watts at 3% distortion all triode, zero feedback.
What, like Lynn Olson? A1 15 watts at 0.3% distortion, and A2 30 watts at 3% distortion all triode, zero feedback.
Triodes work by allowing the anode voltage to feed back against the grid voltage. No feedback means no triodes allowed, so you have to use tetrodes or pentodes.
Who said anything about no feedback ? Are you been obtuse ?
There are many types of feedback.
Shoog
I did say 'properly applied' - that includes stability. Some valve amps overdid it, given the quality of their OPT. Even the 5-20 shows some LF wobbles.richwalters said:
However, 30-35dB of feedback is only 'shocking' to people who think in terms of 6db feedback: enough to generate re-entrant distortion unless the open loop response is excellent but not enough to suppress it very much.
Sorry, that's being disingenuous.
Every single amplifying device has a dependency on anode/collector/drain conditions.
This reminds me of a "best sporst car of the year" article where the Lotus and Porsche were removed for "fundamental handling flaws". The car with the full page advertisements naturally won.
so back in 1947, there seemed to be a clear winner because the valve amp industry is still talking about what a splash that Williamson design made in the industry back then. It seems to be the most talked about amp of that era.
But in the last 10 to 20 years, it seems that no new valve amp design has emerged to become "the clear winner". Which valve amp design from the last two decades will still be highly regarded in the future 60 years from now?
I know that the debate can go on for ever but as with any debate, there's a majority and a minority and the other groups in between. So I guess a poll is really the best way to see which slice of the pie gets the most votes. But then you'd have to create a list of candidates....and you'd need like a large sample size of voters.
I will attempt to set up a poll and I will post a topic for the sole purpose of gathering a list of candidates that will become poll option in the poll. It will be very interesting to see which valve amp design from the last two decades gets the most votes. Even tho we all know that the poll will not be perfect due to the myriad variables...it will still be fun and interesting
But in the last 10 to 20 years, it seems that no new valve amp design has emerged to become "the clear winner". Which valve amp design from the last two decades will still be highly regarded in the future 60 years from now?
I know that the debate can go on for ever but as with any debate, there's a majority and a minority and the other groups in between. So I guess a poll is really the best way to see which slice of the pie gets the most votes. But then you'd have to create a list of candidates....and you'd need like a large sample size of voters.
I will attempt to set up a poll and I will post a topic for the sole purpose of gathering a list of candidates that will become poll option in the poll. It will be very interesting to see which valve amp design from the last two decades gets the most votes. Even tho we all know that the poll will not be perfect due to the myriad variables...it will still be fun and interesting
Your method of jumping to conclusions is now out for everyone to see.
Can you tell me how much reading I've done in the last 4 weeks?
You could not be more wrong. How did you come to the conclusion (or should I say ASSumption) that I "dropped" wanting to learn. I have read 20 to 30 percent of eleven different books until I found NEETS. I have read the entire first module of NEETS and taken the tests and about to start module two. In the last seven days alone I have read an average of 3 hours per day and 6 hours on some days.
And why do you stretch what I say so that it makes me look bad... when did I say "accept voice commands". I did not say that. In fact, you are trying to make me look bad with your lies. I've heard that those who are insecure will lift themselves up by putting others down. So maybe you feel a little more secure now.
Sometimes beginners flounder around aimlessly shooting here and there trying to find their direction in the dark. Of course I haven't found my direction yet....but I will.
Obviously I must ensure that I never accept any advice from you because when you assume things it can be far far off from the truth. And you're very quick to assume with very little information, in fact, you know nothing about me, which is why you came to the wrong assumption.
Do they have that saying over there "...you know what assume does..."
I would suggest that you delete your post so that I can delete this one, to clean it up and be more civil.
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I think you misunderstood. And I am sorry for that.
My point was that you try to make sense of all these things too fast. Not gonna happen that easy. Do you know how long it took me to design my first amp? 3 years. And it is a kinda simple one. I listen to it even as we speak. 🙂 And that was after successfully building two more from schematics I found on the net! But for like 2-3 years I devoured every pdf I could find, and this forum too, almost every afternoon.
I know what assume means. My ex hippie american boss of one time explained it to me. 😛
In most cases only at the margins. Only for the triode (and, to some extent, the JFET) is the device linearity (in the right circuit) a matter of internal feedback. You can buy a triode with no feedback: it is called a pentode.thoglette said:
All I was pointing out is that those who don't like feedback (Blackophobes) must avoid triodes (and degeneration, and followers).
Yes, but I think it was more about getting the amp stable with todays loudspeaker loads.
From what I read about the Williamson (I have never built one) its not easy to make it
stable, even more so if you want to lower the closed loop gain for todays high level (compared to the 50ties) line sources.
SY can I suggest you go back to building with opamps where you can achieve exactly what you want with minimal fuss and expense 😉
Shoog
Shoog
It's not as hard these days to get it stable: there's no shortage of excellent wide-band transformers, and the main source of LF instability (the time constants of the RC coupling) was sorted out in the mid to late 1950s. I have built one variation and it worked very well indeed, no signs of LF or HF instability. If I were to do it again, I'd probably go for a pentode output with multiple internal feedback loops between the output tubes and the driver circuit, similar to the concept used in the RCA tube manual 50 watter.
People who dislike global feedback often seem to want to make a religion of it. To show how pure they are they disavow all feedback, then proceed to design circuits which include lots of feedback!
Now of course global feedback, like all multi-stage feedback, has potential problems related to stability and overload before any integrator but it is not fundamentally different from local feedback. It obeys the same maths so, for example, is subject to the same re-entrant distortion.
Now of course global feedback, like all multi-stage feedback, has potential problems related to stability and overload before any integrator but it is not fundamentally different from local feedback. It obeys the same maths so, for example, is subject to the same re-entrant distortion.
The type of feedback effects every aspect of the components it is applied to, in complex ways.
Take for example plate to grid feedback which both changes the behaviour of the device it is applied to as well as making demands on the driver. Each feedback is different and effects the circuit differently.
All of the designers who I have come to respect for the quality of the products they produce, and which I have experimented with their design prionciples myself, askew the use of gNFB because of the sheer blandness of the resulting product. I build to enjoy the music so refuse to be satisfied with bland results.
Shoog
Take for example plate to grid feedback which both changes the behaviour of the device it is applied to as well as making demands on the driver. Each feedback is different and effects the circuit differently.
All of the designers who I have come to respect for the quality of the products they produce, and which I have experimented with their design prionciples myself, askew the use of gNFB because of the sheer blandness of the resulting product. I build to enjoy the music so refuse to be satisfied with bland results.
Shoog
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