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#401
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MOSFET output stage
Jorden Verwer wrote:
Don Pearce wrote: Jorden Verwer wrote: JosephKK wrote: Noise-like phenomena, in increasing order of bandwith: Offset == 1/f noise == white noise OK alligator, where does shot noise fall in the spectrum? I never claimed that the list was exhausistive, but to answer your question: I would put it between 1/f noise and white noise. The spectrum of shot noise is white - why would it be otherwise? Shot noise will always be band limited because electrons have a nonzero transit time. Its bandwith is very high, but not infinite. Not helpful - in audio terms and a long, long way beyond, it is white. d |
#402
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MOSFET output stage
JosephKK wrote:
On Thu, 18 Sep 2008 18:26:25 -0000, "Jorden Verwer" wrote: Eeyore wrote: given that you've apparently never heard of the term offset. Offset is IRRELEVANT to output devices you complete MORON ! I know that, and I never claimed otherwise. Offset is a form of noise, in a sense. And like noise, it is caused almost completely by the input transistors. I'm well aware of all that. Do do you know what a 'closed loop' means ? Yes. Offset is a form of noise???? This is the first time i have ever heard that. Not for me. Its very common interpretation. There is no engineering reason to look at it that way. There is to me, and to many others. is fundamentally a different property with different physics. Offset is an error. Noise is an error. For example, the standard method of analysing Sigma-Delta converters is to treat what is, technically, an error in coding a signal from its actual value, as an additional *noise* source, that is considered to be unrelated to the signal, when in fact, it is! I don't see that it matters much where the error comes from, it can be handled in the same general way. Kevin Aylward www.kevinaylward.co.uk |
#403
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
JosephKK wrote:
On Fri, 19 Sep 2008 15:21:19 GMT, "Kevin Aylward" wrote: it. Not at all in any remote way shape or form. Don't you at least agree there are many similarities between 1/f noise and offset? Actually, I do. By and large, they amount to the same thing. Its all low frequency variations. For example, if one designs a chopper amp to get low offset, it also kills/corrects for 1/f noise as well. If one has 1/f problems in an system, one immediately thinks about using a chopper..well I do any way... Kevin Aylward www.anasoft.co.uk SuperSpice I am less sure about it killing 1/f (flicker) noise rather than band shifting it to a place where is can be filtered out. It is not offset, though the chopper amplifiers can mask it out. I don't see who its physical possible to distinguish between a random dc offset, and random noise. If offset is completely fixed, never moves with time, we can ignore it as we can just subtract it with certainty. Its only if it moves that it concerns us, well, except for having 1A continuous through a speaker coil.... Ah, yes, noise shaping; making some undesired near band interfering signal content terms go where they are easier to separate from the desired signal. already addressed by the other fellows post. Kevin Aylward www.kevinaylward.co.uk |
#404
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Kevin Aylward wrote:
JosephKK wrote: On Thu, 18 Sep 2008 18:26:25 -0000, "Jorden Verwer" wrote: Eeyore wrote: given that you've apparently never heard of the term offset. Offset is IRRELEVANT to output devices you complete MORON ! I know that, and I never claimed otherwise. Offset is a form of noise, in a sense. And like noise, it is caused almost completely by the input transistors. I'm well aware of all that. Do do you know what a 'closed loop' means ? Yes. Offset is a form of noise???? This is the first time i have ever heard that. Not for me. Its very common interpretation. There is no engineering reason to look at it that way. There is to me, and to many others. is fundamentally a different property with different physics. Offset is an error. Noise is an error. For example, the standard method of analysing Sigma-Delta converters is to treat what is, technically, an error in coding a signal from its actual value, as an additional *noise* source, that is considered to be unrelated to the signal, when in fact, it is! I don't see that it matters much where the error comes from, it can be handled in the same general way. Kevin Aylward www.kevinaylward.co.uk It can be handled the same way, but doesn't need to be. Noise must be handled by filtering, with with a specific inline filter or effective filtering by means of a control loop. DC will also be handled that way, but for DC there is always the option of trimming it away with either an adjustable or an SOT. You can't do that with noise, which makes them fundamentally different things. d |
#405
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
In article , Rich Grise wrote:
On Wed, 24 Sep 2008 08:33:17 -0400, Arny Krueger wrote: "Eeyore" wrote in I expect the phone would be good enough for you ? Depends on the phone. If I make a phone up out of a good vocal mic and some studio monitors, it will be pretty good. These days really good electret mics cost pennies, while good earphone elements are relatively small and cheap compared to speakers. Most of the inherent losses in modern phones are in the communications channel, which is wildly bandwidth-reduced. As bandwidth becomes cheaper, there is a possibility that good-sounding telephones will become commonplace. If NASA can send broadcast quality video down from the shuttle or ISS, howcome their audio still sounds like a fast food clown? Thanks, Rich I don't know whats used today, but the Apollo stuff used Motorola communications units much the same as standard variety sets. Those were also on a separate antenna system from the unified S Band. Those bandwidths also were much the same as standard communication links inside the tracking sites and links to mission control. greg |
#406
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Don Pearce writes:
Jorden Verwer wrote: Don Pearce wrote: Jorden Verwer wrote: JosephKK wrote: Noise-like phenomena, in increasing order of bandwith: Offset == 1/f noise == white noise OK alligator, where does shot noise fall in the spectrum? I never claimed that the list was exhausistive, but to answer your question: I would put it between 1/f noise and white noise. The spectrum of shot noise is white - why would it be otherwise? Shot noise will always be band limited because electrons have a nonzero transit time. Its bandwith is very high, but not infinite. Not helpful - in audio terms and a long, long way beyond, it is white. Don, Perhaps your definition of white is different than mine. There are two I've seen: one says pretty much directly that it is noise with infinite bandwidth, and the other implies it through the relationship of a Dirac delta function (the autocorrelation function of an uncorrelated white noise process) and the Fourier Transform. You can find those definitions in this short paper on the unrelated topic of the DC value of white noise: http://www.digitalsignallabs.com/white.pdf --Randy -- % Randy Yates % "She has an IQ of 1001, she has a jumpsuit %% Fuquay-Varina, NC % on, and she's also a telephone." %%% 919-577-9882 % %%%% % 'Yours Truly, 2095', *Time*, ELO http://www.digitalsignallabs.com |
#407
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Don Pearce wrote: Kevin Aylward wrote: JosephKK wrote: On Thu, 18 Sep 2008 18:26:25 -0000, "Jorden Verwer" wrote: Eeyore wrote: given that you've apparently never heard of the term offset. Offset is IRRELEVANT to output devices you complete MORON ! I know that, and I never claimed otherwise. Offset is a form of noise, in a sense. And like noise, it is caused almost completely by the input transistors. I'm well aware of all that. Do do you know what a 'closed loop' means ? Yes. Offset is a form of noise???? This is the first time i have ever heard that. Not for me. Its very common interpretation. There is no engineering reason to look at it that way. There is to me, and to many others. is fundamentally a different property with different physics. Offset is an error. Noise is an error. For example, the standard method of analysing Sigma-Delta converters is to treat what is, technically, an error in coding a signal from its actual value, as an additional *noise* source, that is considered to be unrelated to the signal, when in fact, it is! I don't see that it matters much where the error comes from, it can be handled in the same general way. It can be handled the same way, but doesn't need to be. Noise must be handled by filtering, with with a specific inline filter or effective filtering by means of a control loop. DC will also be handled that way, but for DC there is always the option of trimming it away with either an adjustable or an SOT. You can't do that with noise, which makes them fundamentally different things. And offset in an audio power amp is commonly corrected by not making it DC coupled. A filter of sorts I suppose. Graham |
#408
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Randy Yates wrote:
Don Pearce writes: Jorden Verwer wrote: Don Pearce wrote: Jorden Verwer wrote: JosephKK wrote: Noise-like phenomena, in increasing order of bandwith: Offset == 1/f noise == white noise OK alligator, where does shot noise fall in the spectrum? I never claimed that the list was exhausistive, but to answer your question: I would put it between 1/f noise and white noise. The spectrum of shot noise is white - why would it be otherwise? Shot noise will always be band limited because electrons have a nonzero transit time. Its bandwith is very high, but not infinite. Not helpful - in audio terms and a long, long way beyond, it is white. Don, Perhaps your definition of white is different than mine. There are two I've seen: one says pretty much directly that it is noise with infinite bandwidth, and the other implies it through the relationship of a Dirac delta function (the autocorrelation function of an uncorrelated white noise process) and the Fourier Transform. You can find those definitions in this short paper on the unrelated topic of the DC value of white noise: http://www.digitalsignallabs.com/white.pdf --Randy My definition of white noise is that equal bandwidths contain equal energy, whatever their centre frequency. Certainly over the full extent of the audio band, and as I say a very long way beyond, that is true for shot noise. There is a sentence in that paper that shows the limitation of Papoulis's theory in that it cannot of itself show that white noise has a zero mean (no DC component). I think the pragmatic definition is probably the more useful and easily understood. d |
#409
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Eeyore wrote:
Don Pearce wrote: Kevin Aylward wrote: JosephKK wrote: On Thu, 18 Sep 2008 18:26:25 -0000, "Jorden Verwer" wrote: Eeyore wrote: given that you've apparently never heard of the term offset. Offset is IRRELEVANT to output devices you complete MORON ! I know that, and I never claimed otherwise. Offset is a form of noise, in a sense. And like noise, it is caused almost completely by the input transistors. I'm well aware of all that. Do do you know what a 'closed loop' means ? Yes. Offset is a form of noise???? This is the first time i have ever heard that. Not for me. Its very common interpretation. There is no engineering reason to look at it that way. There is to me, and to many others. is fundamentally a different property with different physics. Offset is an error. Noise is an error. For example, the standard method of analysing Sigma-Delta converters is to treat what is, technically, an error in coding a signal from its actual value, as an additional *noise* source, that is considered to be unrelated to the signal, when in fact, it is! I don't see that it matters much where the error comes from, it can be handled in the same general way. It can be handled the same way, but doesn't need to be. Noise must be handled by filtering, with with a specific inline filter or effective filtering by means of a control loop. DC will also be handled that way, but for DC there is always the option of trimming it away with either an adjustable or an SOT. You can't do that with noise, which makes them fundamentally different things. And offset in an audio power amp is commonly corrected by not making it DC coupled. A filter of sorts I suppose. Graham I think that since these days 99% of audio amps are configured as op amps, DC offset is most commonly handled by the feedback loop - the second kind I listed. d |
#410
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Don Pearce wrote: Eeyore wrote: Don Pearce wrote: Kevin Aylward wrote: JosephKK wrote: On Thu, 18 Sep 2008 18:26:25 -0000, "Jorden Verwer" wrote: Eeyore wrote: given that you've apparently never heard of the term offset. Offset is IRRELEVANT to output devices you complete MORON ! I know that, and I never claimed otherwise. Offset is a form of noise, in a sense. And like noise, it is caused almost completely by the input transistors. I'm well aware of all that. Do do you know what a 'closed loop' means ? Yes. Offset is a form of noise???? This is the first time i have ever heard that. Not for me. Its very common interpretation. There is no engineering reason to look at it that way. There is to me, and to many others. is fundamentally a different property with different physics. Offset is an error. Noise is an error. For example, the standard method of analysing Sigma-Delta converters is to treat what is, technically, an error in coding a signal from its actual value, as an additional *noise* source, that is considered to be unrelated to the signal, when in fact, it is! I don't see that it matters much where the error comes from, it can be handled in the same general way. It can be handled the same way, but doesn't need to be. Noise must be handled by filtering, with with a specific inline filter or effective filtering by means of a control loop. DC will also be handled that way, but for DC there is always the option of trimming it away with either an adjustable or an SOT. You can't do that with noise, which makes them fundamentally different things. And offset in an audio power amp is commonly corrected by not making it DC coupled. A filter of sorts I suppose. I think that since these days 99% of audio amps are configured as op amps, DC offset is most commonly handled by the feedback loop - the second kind I listed. Gross offset from mismatched power devices, yes. I was thinking of that from the input pair. Of course lateral fets aren't subject to the gross offset problem. Graham |
#411
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Eeyore wrote:
Don Pearce wrote: Eeyore wrote: Don Pearce wrote: Kevin Aylward wrote: JosephKK wrote: On Thu, 18 Sep 2008 18:26:25 -0000, "Jorden Verwer" wrote: Eeyore wrote: given that you've apparently never heard of the term offset. Offset is IRRELEVANT to output devices you complete MORON ! I know that, and I never claimed otherwise. Offset is a form of noise, in a sense. And like noise, it is caused almost completely by the input transistors. I'm well aware of all that. Do do you know what a 'closed loop' means ? Yes. Offset is a form of noise???? This is the first time i have ever heard that. Not for me. Its very common interpretation. There is no engineering reason to look at it that way. There is to me, and to many others. is fundamentally a different property with different physics. Offset is an error. Noise is an error. For example, the standard method of analysing Sigma-Delta converters is to treat what is, technically, an error in coding a signal from its actual value, as an additional *noise* source, that is considered to be unrelated to the signal, when in fact, it is! I don't see that it matters much where the error comes from, it can be handled in the same general way. It can be handled the same way, but doesn't need to be. Noise must be handled by filtering, with with a specific inline filter or effective filtering by means of a control loop. DC will also be handled that way, but for DC there is always the option of trimming it away with either an adjustable or an SOT. You can't do that with noise, which makes them fundamentally different things. And offset in an audio power amp is commonly corrected by not making it DC coupled. A filter of sorts I suppose. I think that since these days 99% of audio amps are configured as op amps, DC offset is most commonly handled by the feedback loop - the second kind I listed. Gross offset from mismatched power devices, yes. I was thinking of that from the input pair. Of course lateral fets aren't subject to the gross offset problem. Graham All depends how the input stage is configured. If the actual input transistor is suitably grounded at its based, and the feedback returns to the base of its Blumlein partner, then all offsets through the entire amplifier chain get added together and corrected as a single item, resulting in the speaker terminal at zero volts, just like the first transistor base. Actually this isn't quite true since that base is offset slightly negative by the base current through the several k resistor. Individual internal nodes will still be non-zero, of course, but if we treat the amplifier as a black box, with only input and output terminals visible, the net offset is always efectively zero. Or rather whatever they would have been if uncorrected divided by the open loop DC gain of the amplifier. d |
#412
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Don Pearce writes:
[...] My definition of white noise is that equal bandwidths contain equal energy, whatever their centre frequency. Certainly over the full extent of the audio band, and as I say a very long way beyond, that is true for shot noise. I agree that shot noise is constant in some bandwidth around a centre frequency that extends "a very long way beyond" the audio band. What I am saying is that, even though the term "white noise" is used colloquially to mean "constant power over some large bandwidth," that usage is wrong according to the definition. It would be useful to coin a new phrase for such bandlimited noise; "bandlimited white noise"? There is a sentence in that paper that shows the limitation of Papoulis's theory in that it cannot of itself show that white noise has a zero mean (no DC component). That was the point of both sections: neither Papoulis' nor Brown's definitions imply zero mean. I think the pragmatic definition is probably the more useful and easily understood. I would agree that myself and pretty much everyone else here understands what is meant by "white" in this context. What I do not agree with is when someone such as Jordan is careful with the terminology and meets with resistance. Jordan is not wrong for using the term "white noise" in its proper form! -- % Randy Yates % "She's sweet on Wagner-I think she'd die for Beethoven. %% Fuquay-Varina, NC % She love the way Puccini lays down a tune, and %%% 919-577-9882 % Verdi's always creepin' from her room." %%%% % "Rockaria", *A New World Record*, ELO http://www.digitalsignallabs.com |
#413
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Randy Yates wrote:
Don Pearce writes: [...] My definition of white noise is that equal bandwidths contain equal energy, whatever their centre frequency. Certainly over the full extent of the audio band, and as I say a very long way beyond, that is true for shot noise. I agree that shot noise is constant in some bandwidth around a centre frequency that extends "a very long way beyond" the audio band. What I am saying is that, even though the term "white noise" is used colloquially to mean "constant power over some large bandwidth," that usage is wrong according to the definition. That wouldn't be my usage - mine is that it is constant within any selected small bandwidths, as long as they are the same. If you measure the noise power over, say half the audio band in one hit, you have no way of judging whether or not it is white. Far better would be to use, say, 10Hz bandwidth measured at manyb centre frequencies from 20Hz to 20kHz. It would be useful to coin a new phrase for such bandlimited noise; "bandlimited white noise"? I'm happy with banlimited white noise, provided that the limited band in question contains everything you are trying to measure. If it doesn't then you can't really use white to describe it. There is a sentence in that paper that shows the limitation of Papoulis's theory in that it cannot of itself show that white noise has a zero mean (no DC component). That was the point of both sections: neither Papoulis' nor Brown's definitions imply zero mean. I think the pragmatic definition is probably the more useful and easily understood. I would agree that myself and pretty much everyone else here understands what is meant by "white" in this context. I thing white in an audio context is easy enough to understand - my first paragraph in my reply covers it. What I do not agree with is when someone such as Jordan is careful with the terminology and meets with resistance. Jordan is not wrong for using the term "white noise" in its proper form! Agreed d |
#414
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Don Pearce wrote:
It can be handled the same way, but doesn't need to be. Noise must be handled by filtering, with with a specific inline filter or effective filtering by means of a control loop. DC will also be handled that way, but for DC there is always the option of trimming it away with either an adjustable or an SOT. You can't do that with noise, which makes them fundamentally different things. Trimming will only cancel the offset that is present at that instant. When it drifts (and it will), you will experience offset again. Adjustable trimming solutions can be viewed as very low bandwidth control loops (with the person doing the adjustments closing the loop). There is no fundamental difference. |
#415
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Don Pearce wrote: Eeyore wrote: Don Pearce wrote: Eeyore wrote: Don Pearce wrote: Kevin Aylward wrote: I don't see that it matters much where the error comes from, it can be handled in the same general way. It can be handled the same way, but doesn't need to be. Noise must be handled by filtering, with with a specific inline filter or effective filtering by means of a control loop. DC will also be handled that way, but for DC there is always the option of trimming it away with either an adjustable or an SOT. You can't do that with noise, which makes them fundamentally different things. And offset in an audio power amp is commonly corrected by not making it DC coupled. A filter of sorts I suppose. I think that since these days 99% of audio amps are configured as op amps, DC offset is most commonly handled by the feedback loop - the second kind I listed. Gross offset from mismatched power devices, yes. I was thinking of that from the input pair. Of course lateral fets aren't subject to the gross offset problem. All depends how the input stage is configured. If the actual input transistor is suitably grounded at its based, and the feedback returns to the base of its Blumlein partner, then all offsets through the entire amplifier chain get added together and corrected as a single item, resulting in the speaker terminal at zero volts, just like the first transistor base. Actually this isn't quite true since that base is offset slightly negative by the base current through the several k resistor. Which is hopefully matched by the feedback circuit resistance. Individual internal nodes will still be non-zero, of course, but if we treat the amplifier as a black box, with only input and output terminals visible, the net offset is always efectively zero. Or rather whatever they would have been if uncorrected divided by the open loop DC gain of the amplifier. Indeed. Graham |
#416
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Jorden Verwer wrote: Don Pearce wrote: It can be handled the same way, but doesn't need to be. Noise must be handled by filtering, with with a specific inline filter or effective filtering by means of a control loop. DC will also be handled that way, but for DC there is always the option of trimming it away with either an adjustable or an SOT. You can't do that with noise, which makes them fundamentally different things. Trimming will only cancel the offset that is present at that instant. When it drifts (and it will), you will experience offset again. Adjustable trimming solutions can be viewed as very low bandwidth control loops (with the person doing the adjustments closing the loop). There is no fundamental difference. My experience is that the DC offset in an audio amp is set for all practical purposes by the typical input long-tailed pair and this is readily trimmed if required by a pot. Or even a servo circuit with a longish time constant. Any drift is most likely to be thermal hence devices like the LM394 and the old practice of glueing 2 TO-92 devices dack-to back. Graham |
#417
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
"Eeyore" wrote in
message Arny Krueger wrote: "Eeyore" wrote Arny Krueger wrote: "Eeyore" wrote: Arny Krueger wrote: I have more highly sensitive audio test gear by accident then most people have on purpose. I probably shouldn't admit this because it shows a certain kind of carelessness. Not more sensitive than Audio Precision or Prism Sound. Better than a Prism Sound ADA-8 Which isn't test equipment anyway. Well, yes and no. With computer testing software, any ADC-DAC can perform as some kind of audio test equipment. Besides, I'm not the one who brought Prism up. or an AP System One. Better than a brilliant 20+ year old design ? No longer in production btw. It's System 2 now. I'd like to know by how much to be honest. The LynxTwo runs neck-and-neck with an AP System 2, according to its designer who of course has one. So not actually 'better' then ? Testing a LynxTwo with an AP2 won't give an answer either way, for obvious reasons. I seem to remember that the designer said that my www.pcavtech.com results for the LynxTwo were significantly better than what he got while measuring it with an AP2. |
#418
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
"Arny Krueger" wrote in message . .. I seem to remember that the designer said that my www.pcavtech.com results for the LynxTwo were significantly better than what he got while measuring it with an AP2. But he must have already done his own loop back tests surely? You don't get results like that by accident :-) MrT. |
#419
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Eeyore wrote: John Larkin wrote: True, none of this is relevant for audio. Anything will work for audio. Almost anything. RCA's 2N3055s weren't exactly the fastest in the world. 800kHz fT IIRC. I hate to think what their germanium predecessors like the OC35 were like. Graham The 3055 was developed for linear power supplies, so it didn't need a high fT. It was scaled down from the RCA 40411, which was a 100 volt device, VS a 60 volt, cheaper device. The 40411 was used in some audio amps in some early RCA semiconductor data books. In fact, the 60 watt amplifier used the 40406, 40407, 40408, 40409, 40410, and a pair of 40411 transistors, and a couple diodes to sense the temperature of the heatsinks. I built a PA amp from that sample design in the late '60s. It, and a preamp were also built on my first hand made PC boards. -- http://improve-usenet.org/index.html aioe.org, Goggle Groups, and Web TV users must request to be white listed, or I will not see your messages. If you have broadband, your ISP may have a NNTP news server included in your account: http://www.usenettools.net/ISP.htm There are two kinds of people on this earth: The crazy, and the insane. The first sign of insanity is denying that you're crazy. |
#420
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
"Michael A. Terrell" wrote: Eeyore wrote: John Larkin wrote: True, none of this is relevant for audio. Anything will work for audio. Almost anything. RCA's 2N3055s weren't exactly the fastest in the world. 800kHz fT IIRC. I hate to think what their germanium predecessors like the OC35 were like. The 3055 was developed for linear power supplies, so it didn't need a high fT. True enough, except Motorola's were faster anyway. Using the wrong brand in hobby kits caused many a burnt out output stage. Eventually I think the slower parts got an H suffix as in RCA's 'hometaxial' process. It was scaled down from the RCA 40411, which was a 100 volt device, VS a 60 volt, cheaper device. The 40411 was used in some audio amps in some early RCA semiconductor data books. In fact, the 60 watt amplifier used the 40406, 40407, 40408, 40409, 40410, and a pair of 40411 transistors, and a couple diodes to sense the temperature of the heatsinks. I built a PA amp from that sample design in the late '60s. It, and a preamp were also built on my first hand made PC boards. I know the very one and still have that handbook. I built one too. The little heatsinks welded onto the drivers were an intriguing novelty that never caught on. In the UK, WEM 100W PA and instrument amps were based on that design for years. They got 100W by using 6 ohm speakers ! Graham |
#421
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
"Michael A. Terrell" wrote in
message m Eeyore wrote: John Larkin wrote: True, none of this is relevant for audio. Anything will work for audio. Almost anything. RCA's 2N3055s weren't exactly the fastest in the world. 800kHz fT IIRC. I hate to think what their germanium predecessors like the OC35 were like. RCA's germanium predecessor to the 2N3055 was arguably the 2N2147. If memory serves, PD = 25 watts, FT = 3 MHz. SOA = negligible. Many of the first generation mass-market *production* hi fi power amps used the 2N2147 with a driver transformer. This included Knight Kit, Heath Kit, Ten Tec, Altec Lansing, etc. Mainstream mid-fi producers like H. H. Scott, Sherwood, and Fisher AFAIK never produced any germanium power amps. Their first generation products were based on 2N3055 and similar devices. The 3055 was developed for linear power supplies, so it didn't need a high fT. AFAIK the first generation data sheets characterized it as both a power supply, servo amp, and audio power amp device. It was scaled down from the RCA 40411, which was a 100 volt device, VS a 60 volt, cheaper device. AFAIK the 40411 was introduced several years after the introduction of the 2N3055. I think that there were at least two years of the RCA solid state book with the 2N305x family in them, before the 404xx family was added. I had a business partner who, in an earlier venture manufactured SS power amps for professional use. He based his top-of-the-line products on the 40411. There was also an even more robust device called the 411. Again, my memory of this is hazy as this was in the late 60s. According to him, he discovered that the 404xx series of devices were mostly sold for automotive uses, such as SS ignition modules. For a while RCA was making these parts literally by the millions. Product consistency was a problem, which they were very effective at exploiting. The middle-of-the-road parts went to the car companies under proprietary part numbers. The really nice parts, the cream of the crop, were skimmed off sold in relatively small volumes as 40411s, mostly for audio. Eventually the car market for 40411-type devices dried up. As the milk dried up, so did the cream. According to my friend, RCA tried various ruses to come up with enough 40411-type devices, but could never equal their original product. He sold a ton of amps that were not durable and was forced out of business. Eventually, he started cutting open devices, both old and new, and found results similar to what we've seen far more recently with counterfeit transistors.. It was his opinion that RCA was sort of counterfeiting their own product. This all happened number of decades ago, and should not be taken as a reflection on the current RCA corp which has been bought and sold at least once since then, and is thus under a different management. |
#422
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Arny Krueger wrote: According to my friend, RCA tried various ruses to come up with enough 40411-type devices, but could never equal their original product. He sold a ton of amps that were not durable and was forced out of business. Eventually, he started cutting open devices, both old and new, and found results similar to what we've seen far more recently with counterfeit transistors.. It was his opinion that RCA was sort of counterfeiting their own product. Seen that with the RCA410 too which they sold as replacement MJ410s. It took thumbscrews to get them to admit they contained dies from 3 seperate lines. A bright tech noticed by the way that there were 3 'hard codes' stamped on the case and 2 of them gave trouble. The 410s were just used as fastish drivers, we were using the 2N3773 by then as main output devices. Seemed solid enough. If they'd been around at the time, they might have saved your friend's company. Graham |
#423
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Arny Krueger wrote: "Michael A. Terrell" wrote in message m Eeyore wrote: John Larkin wrote: True, none of this is relevant for audio. Anything will work for audio. Almost anything. RCA's 2N3055s weren't exactly the fastest in the world. 800kHz fT IIRC. I hate to think what their germanium predecessors like the OC35 were like. RCA's germanium predecessor to the 2N3055 was arguably the 2N2147. If memory serves, PD = 25 watts, FT = 3 MHz. SOA = negligible. Many of the first generation mass-market *production* hi fi power amps used the 2N2147 with a driver transformer. This included Knight Kit, Heath Kit, Ten Tec, Altec Lansing, etc. Mainstream mid-fi producers like H. H. Scott, Sherwood, and Fisher AFAIK never produced any germanium power amps. Their first generation products were based on 2N3055 and similar devices. The 3055 was developed for linear power supplies, so it didn't need a high fT. AFAIK the first generation data sheets characterized it as both a power supply, servo amp, and audio power amp device. It was scaled down from the RCA 40411, which was a 100 volt device, VS a 60 volt, cheaper device. AFAIK the 40411 was introduced several years after the introduction of the 2N3055. I think that there were at least two years of the RCA solid state book with the 2N305x family in them, before the 404xx family was added. I bought some 40411 transistors in the '60s, and the product release for the 2N3055 stated that it was developed as a 60 volt version for linear power supplies. Pupular Electronics used the RCA sample circuit for their 'Brute 70' amplifier. http://www.swtpc.com/mholley/Popular...PE_Feb1967.htm I had a business partner who, in an earlier venture manufactured SS power amps for professional use. He based his top-of-the-line products on the 40411. There was also an even more robust device called the 411. Again, my memory of this is hazy as this was in the late 60s. According to him, he discovered that the 404xx series of devices were mostly sold for automotive uses, such as SS ignition modules. For a while RCA was making these parts literally by the millions. Product consistency was a problem, which they were very effective at exploiting. The middle-of-the-road parts went to the car companies under proprietary part numbers. The really nice parts, the cream of the crop, were skimmed off sold in relatively small volumes as 40411s, mostly for audio. Eventually the car market for 40411-type devices dried up. As the milk dried up, so did the cream. According to my friend, RCA tried various ruses to come up with enough 40411-type devices, but could never equal their original product. He sold a ton of amps that were not durable and was forced out of business. Eventually, he started cutting open devices, both old and new, and found results similar to what we've seen far more recently with counterfeit transistors.. It was his opinion that RCA was sort of counterfeiting their own product. This all happened number of decades ago, and should not be taken as a reflection on the current RCA corp which has been bought and sold at least once since then, and is thus under a different management. -- http://improve-usenet.org/index.html aioe.org, Goggle Groups, and Web TV users must request to be white listed, or I will not see your messages. If you have broadband, your ISP may have a NNTP news server included in your account: http://www.usenettools.net/ISP.htm There are two kinds of people on this earth: The crazy, and the insane. The first sign of insanity is denying that you're crazy. |
#424
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Eeyore wrote: Arny Krueger wrote: According to my friend, RCA tried various ruses to come up with enough 40411-type devices, but could never equal their original product. He sold a ton of amps that were not durable and was forced out of business. Eventually, he started cutting open devices, both old and new, and found results similar to what we've seen far more recently with counterfeit transistors.. It was his opinion that RCA was sort of counterfeiting their own product. Seen that with the RCA410 too which they sold as replacement MJ410s. It took thumbscrews to get them to admit they contained dies from 3 seperate lines. A bright tech noticed by the way that there were 3 'hard codes' stamped on the case and 2 of them gave trouble. The 410s were just used as fastish drivers, we were using the 2N3773 by then as main output devices. Seemed solid enough. If they'd been around at the time, they might have saved your friend's company. Graham I used a lot of 2N3773 to replace 40411, and some other 100 volt transistors. I think I still have one pair left in stock. -- http://improve-usenet.org/index.html aioe.org, Goggle Groups, and Web TV users must request to be white listed, or I will not see your messages. If you have broadband, your ISP may have a NNTP news server included in your account: http://www.usenettools.net/ISP.htm There are two kinds of people on this earth: The crazy, and the insane. The first sign of insanity is denying that you're crazy. |
#425
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
"Michael A. Terrell" wrote: Eeyore wrote: Arny Krueger wrote: According to my friend, RCA tried various ruses to come up with enough 40411-type devices, but could never equal their original product. He sold a ton of amps that were not durable and was forced out of business. Eventually, he started cutting open devices, both old and new, and found results similar to what we've seen far more recently with counterfeit transistors.. It was his opinion that RCA was sort of counterfeiting their own product. Seen that with the RCA410 too which they sold as replacement MJ410s. It took thumbscrews to get them to admit they contained dies from 3 seperate lines. A bright tech noticed by the way that there were 3 'hard codes' stamped on the case and 2 of them gave trouble. The 410s were just used as fastish drivers, we were using the 2N3773 by then as main output devices. Seemed solid enough. If they'd been around at the time, they might have saved your friend's company. I used a lot of 2N3773 to replace 40411, and some other 100 volt transistors. I think I still have one pair left in stock. They were such good replacements for almost all the (predominantly npn) output devices of the day that I may have about half to a third of a tray of them lying about somewhere still ! Graham |
#426
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
"Michael A. Terrell" wrote: Eeyore wrote: Arny Krueger wrote: According to my friend, RCA tried various ruses to come up with enough 40411-type devices, but could never equal their original product. He sold a ton of amps that were not durable and was forced out of business. Eventually, he started cutting open devices, both old and new, and found results similar to what we've seen far more recently with counterfeit transistors.. It was his opinion that RCA was sort of counterfeiting their own product. Seen that with the RCA410 too which they sold as replacement MJ410s. It took thumbscrews to get them to admit they contained dies from 3 seperate lines. A bright tech noticed by the way that there were 3 'hard codes' stamped on the case and 2 of them gave trouble. The 410s were just used as fastish drivers, we were using the 2N3773 by then as main output devices. Seemed solid enough. If they'd been around at the time, they might have saved your friend's company. I used a lot of 2N3773 to replace 40411, and some other 100 volt transistors. I think I still have one pair left in stock. Oh and the 3773 had a 140V rating with correspondingly larger SOA IIRC. Modern MJ1502Xs make it look silly now but it was THE high power audio output device of the day. Graham |
#427
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
"Arny Krueger" wrote in message
"Michael A. Terrell" wrote in message m It was scaled down from the RCA 40411, which was a 100 volt device, VS a 60 volt, cheaper device. AFAIK the 40411 was introduced several years after the introduction of the 2N3055. I think that there were at least two years of the RCA solid state book with the 2N305x family in them, before the 404xx family was added. To shed a little more light: http://www.ck722museum.com/history/r...isel_Page3.htm "After several chip design changes and some significant package cost reductions the 2N1486 and 2N1490 migrated into the 2N3054 and 2N3055 which became industry workhorse standards. The package redesigns were done by Milt Grimes. The 2N3055 was the first multi-amp silicon power transistor to sell for less than one dollar! It was a huge success in the power supply market. In 1965, the team of Design, Production, and Applications engineers who launched these devices got RCA Electronic Components Achievement Awards, which were quite generous." I'm not an IEEE member, but this relevant article is online for those who a http://ieeexplore.ieee.org/Xplore/lo...rnumber=960371 " The 2N3055: a case history Ellis, J.N.; Osadchy, V.S. Electron Devices, IEEE Transactions on Volume 48, Issue 11, Nov 2001 Page(s):2477 - 2484 Digital Object Identifier 10.1109/16.960371 Summary:The 2N3055 power transistor was introduced by the Radio Corporation of America (RCA) in the early 1960s. It was one of the first silicon power transistors, offered unrivalled second breakdown immunity and found many applications particularly in audio power amplifiers and linear power supplies. Other companies tried to copy it with varying degrees of success: one company acknowledges it now by naming a power MOSFET after it. We trace its history, manufacture and eventual decline against pressure from competing technologies. Modern simulation tools have been used to investigate the operation of the device which illustrate its good, and not so good, features. We also relate its geometry to a SPICE model. Neither of these tools would have been available to the original developers. We propose that this transistor be given a place in the archives of history, ranked alongside other famous devices of the 20th century such as the 300B tube " |
#428
Posted to sci.electronics.design,rec.audio.tech
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MOSFET output stage
Arny Krueger wrote: "Arny Krueger" wrote "Michael A. Terrell" wrote in It was scaled down from the RCA 40411, which was a 100 volt device, VS a 60 volt, cheaper device. AFAIK the 40411 was introduced several years after the introduction of the 2N3055. I think that there were at least two years of the RCA solid state book with the 2N305x family in them, before the 404xx family was added. To shed a little more light: http://www.ck722museum.com/history/r...isel_Page3.htm "After several chip design changes and some significant package cost reductions the 2N1486 and 2N1490 migrated into the 2N3054 and 2N3055 which became industry workhorse standards. The package redesigns were done by Milt Grimes. The 2N3055 was the first multi-amp silicon power transistor to sell for less than one dollar! It was a huge success in the power supply market. In 1965, the team of Design, Production, and Applications engineers who launched these devices got RCA Electronic Components Achievement Awards, which were quite generous." I'm not an IEEE member, but this relevant article is online for those who a http://ieeexplore.ieee.org/Xplore/lo...rnumber=960371 " The 2N3055: a case history Ellis, J.N.; Osadchy, V.S. Electron Devices, IEEE Transactions on Volume 48, Issue 11, Nov 2001 Page(s):2477 - 2484 Digital Object Identifier 10.1109/16.960371 Summary:The 2N3055 power transistor was introduced by the Radio Corporation of America (RCA) in the early 1960s. It was one of the first silicon power transistors, offered unrivalled second breakdown immunity and found many applications particularly in audio power amplifiers and linear power supplies. Other companies tried to copy it with varying degrees of success: one company acknowledges it now by naming a power MOSFET after it. We trace its history, manufacture and eventual decline against pressure from competing technologies. Modern simulation tools have been used to investigate the operation of the device which illustrate its good, and not so good, features. We also relate its geometry to a SPICE model. Neither of these tools would have been available to the original developers. We propose that this transistor be given a place in the archives of history, ranked alongside other famous devices of the 20th century such as the 300B tube " Orange ? or was it Wem ? made probably the world's first SS 1kW amplifier using them IIRC. I was called the Killerwatt or somesuch. Because the supply rails were so low the load had to be something like one or two ohms, unheard of in those days, but acheived simply by multiple paralleled speakers. Graham |
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