You keep 32 tabs open all the time? I bet you have a desktop with wall to wall packed small icons too.
26 on Chrome and 29 on Mozilla with NoScript. The computer is near my work table. I am lurking time to time to FB and forum. 🙂
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Sad, but I have already 8 members in my ignore-list... :-(
Why their posts still show in the thread, though closed?
Why their posts still show in the thread, though closed?
Tubes are inherently more linear than semiconductors all by themselves. I would love to hear your amp, Wavebourn, and perhaps I will at the BA meeting.
what are some of those tube numbers that still exist and were USA made that you have tried/recommend?? 6922 6DJ8 but for power...... ?
THx-RNMarsh
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The problem with NOS USA made tubes is, as soon as they are praised in some thread on http://www.diyaudio.com/forums/tubes-valves/ forum, somebody buys almost all that it is today for sale increasing prices. 6922 and 6DJ8 are already overpriced, so you can speak about them aloud.
No, I do not use them. 🙂
No, I do not use them. 🙂
I threw out boxes full of 6DJ8 years ago in little green sealed cans. Just taking up space at the time in a radio shop. Tubes do wear out VS Silicon but that is part of the fun. Some of the tubes in transmitters I used to work on lasted many years of continuous heavy use.
My daughter in Russia threw a big box of new 6J32P tubes (like EF86), and another box of 6E2P (like EM81 magic eyes) out of closet... She nor her husband don't remember how it happened... 😀
While I was working at Alesis as the Service Center Admin. I talked to a gent. from Florida. He worked for NASA (retired). Just a year earlier he tossed a few buckets of tubes. They were mostly good. It was policy that when a unit was tested if anything caused the test to fail, even stupid stuff like forgetting any wire connection, the unit was to be re-tubed.
This is not enough to make a more linear power amplifier. In fact, power amplifier designed with tubes only is and will always be less linear than at least average power amplifier design with transistors and will always be less capable to drive low impedance loads. For those who do not agree, put your arguments in measurement examples, not by verbal adoration of the tube sound.
Can I ask a tech question. It is about loop gain and noise gain etc. Can't get it clear in my head.
Suppose I want to know the loop gain of a circuit. As I understand, it is the gain you see going around the loop with inputs grounded. So in an inverting feedback amplifier going around the loop I see beta and then open loop gain, with a minus sign, so loop gain is -β*Ao.
Physically I interpret the loop gain as the 'space' between the open loop curve and the closed loop gain curve, available for error reduction.
Doing this exercise for an inverting amplifier, I get the same value for loop gain, -β*Ao, so I conclude the loop gain is the same, and I have the same error reduction 'space'.
But. Should we not consider the 'space' between the noise gain and the open loop gain as the available gain for error reduction? If we do, we see that in the inverting case the noise gain is higher and thus error reduction space lower. Should we then in the non-inverting case not also have a different loop gain?
What am I missing here?
Jan
Suppose I want to know the loop gain of a circuit. As I understand, it is the gain you see going around the loop with inputs grounded. So in an inverting feedback amplifier going around the loop I see beta and then open loop gain, with a minus sign, so loop gain is -β*Ao.
Physically I interpret the loop gain as the 'space' between the open loop curve and the closed loop gain curve, available for error reduction.
Doing this exercise for an inverting amplifier, I get the same value for loop gain, -β*Ao, so I conclude the loop gain is the same, and I have the same error reduction 'space'.
But. Should we not consider the 'space' between the noise gain and the open loop gain as the available gain for error reduction? If we do, we see that in the inverting case the noise gain is higher and thus error reduction space lower. Should we then in the non-inverting case not also have a different loop gain?
What am I missing here?
Jan
Noise Gain vs. Signal Gain | Analog Devices
Loop and noise gain is conserved, just forward gain differs.
Loop and noise gain is conserved, just forward gain differs.
Thanks, good link. Found a lot on Google but not this one which addresses exactly my query.
So, if I want to judge stability (gain/phase margin) I should use the noise gain version of the loop gain.
For the inverting config loop gain is -β*Ao; for the non-inverting version it is (β+1)*Ao. Right?
Jan
So, if I want to judge stability (gain/phase margin) I should use the noise gain version of the loop gain.
For the inverting config loop gain is -β*Ao; for the non-inverting version it is (β+1)*Ao. Right?
Jan
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