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#1
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MOSFET output stage
Who do MOSFET sound better than bipolar, as an audio amp output
driver? -- Rich |
#2
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MOSFET output stage
RichD wrote in news:b78fc9c2-fe9c-444c-8ac5-
: Who do MOSFET sound better than bipolar, as an audio amp output driver? They do? Seems like it's possible to design good amplifiers either way. --Damon |
#3
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MOSFET output stage
On Sep 17, 6:12*pm, RichD wrote:
Who do MOSFET sound better than bipolar, as an audio amp output driver? -- Rich MOSFETS HAVE WIDER BANDWIDTH ,less phase shift , lower odd harmonic distortin. on and on. |
#4
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MOSFET output stage
RichD wrote: Who do MOSFET sound better than bipolar, as an audio amp output driver? As a driver ? Now if you said as an output stage it might make sense. Graham |
#5
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MOSFET output stage
In article ,
Damon Hill wrote: RichD wrote in news:b78fc9c2-fe9c-444c-8ac5- : Who do MOSFET sound better than bipolar, as an audio amp output driver? They do? Seems like it's possible to design good amplifiers either way. --Damon Exactly - zero difference in quality capabilities. It's usually a matter of impedance matching. Silicon transistors have a fixed loss around 0.5 volts. MOSFETs have a resistive loss inversely proportional to their voltage rating. That usually makes MOSFETs less expensive for low impedances and transistors less expensive for high impedances. -- Google is a pro-spamming service. I will not see your reply if you use Google. |
#6
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MOSFET output stage
"RichD" wrote in message ... Who do MOSFET sound better than bipolar, as an audio amp output driver? **Non-sequitur. If you're saying that MOSFET outputs sound better, they don't. As a device, operating at typical bias currents (say) 10-50mA, MOSFETs exhibit VASTLY more THD than BJTs. Only when bias currents are elevated (around 0.5A - 1A) do MOSFETs exhibit THD characteristics which are almost as good as BJTs. MOSFETs are very tough, have an exceptional ability to deliver high power, high frequency audio (and RF), but distortion is very high. They require lots of Global NFB in order to operate linearly. MOSFETs do not sound better than BJTs. At best, they can sound as good. All things being equal. -- Trevor Wilson www.rageaudio.com.au |
#7
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MOSFET output stage
"Trevor Wilson" "RichD" Who do MOSFET sound better than bipolar, as an audio amp output driver? **Non-sequitur. If you're saying that MOSFET outputs sound better, they don't. As a device, ** Same old red-herring ******** from know nothing Wilson. It is totally irrelevant how DEVICES behave on their own. Only when they are properly configured and suitably biased in a complimentary output stage can performances be compared. operating at typical bias currents (say) 10-50mA, MOSFETs exhibit VASTLY more THD than BJTs. ** UTTER ******** !!! When configured in typical amplifier topologies, THD is vanishingly small at all power levels and with minimal bias current. This is true for LATERAL mosfets as made by Hitachi and Semelab ( ie 2SK176, BUZ905 etc ). Switching mosfets ( ie IRFPxxx etc) are not the same. ...... Phil |
#8
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MOSFET output stage
In article ,
"Trevor Wilson" wrote: "RichD" wrote in message ... Who do MOSFET sound better than bipolar, as an audio amp output driver? **Non-sequitur. If you're saying that MOSFET outputs sound better, they don't. As a device, operating at typical bias currents (say) 10-50mA, MOSFETs exhibit VASTLY more THD than BJTs. Only when bias currents are elevated (around 0.5A - 1A) do MOSFETs exhibit THD characteristics which are almost as good as BJTs. MOSFETs are very tough, have an exceptional ability to deliver high power, high frequency audio (and RF), but distortion is very high. They require lots of Global NFB in order to operate linearly. That's nonsense. MOSFETs have a lower voltage gain, more capacitive load, and infinite DC current gain. If you swap your bipolar transistors for MOSFETs and crank up the bias voltage, yeah, it will run like crap because the local feedback gain is totally wrong. It might even incapacitate every radio within two blocks of your home then violently explode. The circuits to drive MOSFETs and bipolars are a little different. MOSFETs do not sound better than BJTs. At best, they can sound as good. All things being equal. -- Google is a pro-spamming service. I will not see your reply if you use Google. |
#9
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MOSFET output stage
"Phil Allison" writes:
"Trevor Wilson" "RichD" Who do MOSFET sound better than bipolar, as an audio amp output driver? **Non-sequitur. If you're saying that MOSFET outputs sound better, they don't. As a device, ** Same old red-herring ******** from know nothing Wilson. It is totally irrelevant how DEVICES behave on their own. Only when they are properly configured and suitably biased in a complimentary output stage can performances be compared. operating at typical bias currents (say) 10-50mA, MOSFETs exhibit VASTLY more THD than BJTs. ** UTTER ******** !!! No it's not. When configured in typical amplifier topologies, THD is vanishingly small at all power levels and with minimal bias current. That may be true, but only because of the negative feedback that Trevor referred to. The basic device IS more nonlinear. It comes down to device physics. MOSFETs, when operating in the saturation region, have a square law relationship between Vgs and Ids. It is only through either a) the application of negative feedback, or b) the reduction of input level (the smaller the operating range, the more approximating linear the Ids/Vgs relationship becomes) that the device distortion is mitigated. -- % Randy Yates % "Maybe one day I'll feel her cold embrace, %% Fuquay-Varina, NC % and kiss her interface, %%% 919-577-9882 % til then, I'll leave her alone." %%%% % 'Yours Truly, 2095', *Time*, ELO http://www.digitalsignallabs.com |
#10
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MOSFET output stage
RichD wrote:
Who do MOSFET sound better than bipolar, as an audio amp output driver? The device properties of BJTs are superior to those of MOSFETs in all respects, except for offset - there MOSFETs have the advantage. Whether you will actually hear this depends on many more factors. |
#11
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MOSFET output stage
Randy Yates writes:
"Phil Allison" writes: "Trevor Wilson" "RichD" Who do MOSFET sound better than bipolar, as an audio amp output driver? **Non-sequitur. If you're saying that MOSFET outputs sound better, they don't. As a device, ** Same old red-herring ******** from know nothing Wilson. It is totally irrelevant how DEVICES behave on their own. Only when they are properly configured and suitably biased in a complimentary output stage can performances be compared. operating at typical bias currents (say) 10-50mA, MOSFETs exhibit VASTLY more THD than BJTs. ** UTTER ******** !!! No it's not. When configured in typical amplifier topologies, THD is vanishingly small at all power levels and with minimal bias current. That may be true, but only because of the negative feedback that Trevor referred to. The basic device IS more nonlinear. It comes down to device physics. MOSFETs, when operating in the saturation region, have a square law relationship between Vgs and Ids. It is only through either a) the application of negative feedback, or b) the reduction of input level (the smaller the operating range, the more approximating linear the Ids/Vgs relationship becomes) that the device distortion is mitigated. PS: See, e.g., [gray] and [razavi]. --Randy @book{gray, title = "Analysis and Design of Analog Integrated Circuits", author = "Paul R. Gray and Paul J. Hurst and Stephen H. Lewis and Robert G. Meyer", publisher = "Wiley", edition = "fourth", year = "2001"} @book{razavi, title = "Design of Analog CMOS Integrated Circuits", author = "Behzad Razavi", publisher = "McGraw-Hill", year = "2001"} -- % Randy Yates % "So now it's getting late, %% Fuquay-Varina, NC % and those who hesitate %%% 919-577-9882 % got no one..." %%%% % 'Waterfall', *Face The Music*, ELO http://www.digitalsignallabs.com |
#12
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MOSFET output stage
"RichD" wrote in message ... Who do MOSFET sound better than bipolar, as an audio amp output driver? -- Rich Well this is probably an urban myth/load of ********, but years ago lots of people were talking about power Mosfets exhibiting different distortion characteristics than BJT's in the same way thermionic valves distort with differening harmonics and sound nicer. Fact or crapology? Gareth. |
#13
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MOSFET output stage
Kevin McMurtrie wrote: In article , Damon Hill wrote: RichD wrote in news:b78fc9c2-fe9c-444c-8ac5- : Who do MOSFET sound better than bipolar, as an audio amp output driver? They do? Seems like it's possible to design good amplifiers either way. --Damon Exactly - zero difference in quality capabilities. It's usually a matter of impedance matching. Silicon transistors have a fixed loss around 0.5 volts. MOSFETs have a resistive loss inversely proportional to their voltage rating. That usually makes MOSFETs less expensive for low impedances and transistors less expensive for high impedances. TOTAL AND COMPLETE GARBAGE. |
#14
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MOSFET output stage
Trevor Wilson wrote: "RichD" wrote Who do MOSFET sound better than bipolar, as an audio amp output driver? **Non-sequitur. If you're saying that MOSFET outputs sound better, they don't. As a device, operating at typical bias currents (say) 10-50mA, MOSFETs exhibit VASTLY more THD than BJTs. Only when bias currents are elevated (around 0.5A - 1A) do MOSFETs exhibit THD characteristics which are almost as good as BJTs. MOSFETs are very tough, have an exceptional ability to deliver high power, high frequency audio (and RF), but distortion is very high. They require lots of Global NFB in order to operate linearly. MOSFETs do not sound better than BJTs. At best, they can sound as good. All things being equal. With the required amount of feedback (which isn't rocket science - just good design) they have no trouble meeting VERY low THDs such as one I designed with 0.0008% THD @ 1 kHz. They sound better because of the predominance of 2nd harmonic distortion and almost complete absence of 3rd and ditto up the range AIUI with even and odd harmonics. GRaham |
#15
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MOSFET output stage
"Kevin McMurtrie" wrote in message ... In article , "Trevor Wilson" wrote: "RichD" wrote in message ... Who do MOSFET sound better than bipolar, as an audio amp output driver? **Non-sequitur. If you're saying that MOSFET outputs sound better, they don't. As a device, operating at typical bias currents (say) 10-50mA, MOSFETs exhibit VASTLY more THD than BJTs. Only when bias currents are elevated (around 0.5A - 1A) do MOSFETs exhibit THD characteristics which are almost as good as BJTs. MOSFETs are very tough, have an exceptional ability to deliver high power, high frequency audio (and RF), but distortion is very high. They require lots of Global NFB in order to operate linearly. That's nonsense. **Er, nope. Here are the specs for a modern high power BJT: http://www.toshiba.com/taec/componen...c//66/7890.pdf Note the hFE vs. Ic. Particularly at elevated temps. It is almost a straight line, from less than 10mA to several Amps. I call that spectacular linearity. Now, I draw your attention to a high power MOSFET: http://www.magnatec-uk.com/pdf/magnatec/BUZ900.pdf Note the characteristics of this device. They're pretty good, but as good as a modern BJT. Here is another, older, worse example: http://www.datasheetarchive.com/pdf-...SA-158541.html Quite ordinary lineariy. MOSFETs have a lower voltage gain, more capacitive load, and infinite DC current gain. If you swap your bipolar transistors for MOSFETs and crank up the bias voltage, yeah, it will run like crap because the local feedback gain is totally wrong. **I never suggested anything of the sort. I mentioned ONLY the intrinsic linearity of the devices. MOSFETs are inferior to BJTs. For now. When installed in an appropriate topology, it is likely that there will be little audible, nor measurable difference between a MOSFET amp and a BJT amp. Device linearity is another story. It might even incapacitate every radio within two blocks of your home then violently explode. The circuits to drive MOSFETs and bipolars are a little different. **Again, not in dispute. The intrinsic linearity, is what I refer to. -- Trevor Wilson www.rageaudio.com.au |
#16
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MOSFET output stage
Phil Allison wrote: "Trevor Wilson" "RichD" Who do MOSFET sound better than bipolar, as an audio amp output driver? **Non-sequitur. If you're saying that MOSFET outputs sound better, they don't. As a device, ** Same old red-herring ******** from know nothing Wilson. It is totally irrelevant how DEVICES behave on their own. Only when they are properly configured and suitably biased in a complimentary output stage can performances be compared. operating at typical bias currents (say) 10-50mA, MOSFETs exhibit VASTLY more THD than BJTs. ** UTTER ******** !!! When configured in typical amplifier topologies, THD is vanishingly small at all power levels and with minimal bias current. This is true for LATERAL mosfets as made by Hitachi and Semelab ( ie 2SK176, BUZ905 etc ). Switching mosfets ( ie IRFPxxx etc) are not the same. Yes. Just for fun once I configured a lateral mosfet output stage with zero feedback. Its THD at almost all power levels was ~ 1%. From that you can get a good idea of the negative feedback required to obtain any THD you like. Lateral mosfets, correctly biased also exhibit virtually NO crossover distortion. This is all but impossible with bipolars due to their inherent transfer characteristics unless operated in pure Class A. Graham |
#17
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MOSFET output stage
Kevin McMurtrie wrote: That's nonsense. MOSFETs have a lower voltage gain Mosfets are used as source followers in an audio output stage you inane idiot. Voltage gain is NOT AN ISSUE, regardless of whether or not your statement is true. Graham |
#18
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MOSFET output stage
Randy Yates wrote: "Phil Allison" writes: When configured in typical amplifier topologies, THD is vanishingly small at all power levels and with minimal bias current. That may be true, but only because of the negative feedback that Trevor referred to. The basic device IS more nonlinear. But when given suitable NFB, the transfer characteristic IS 'cleaner'. Very little odd harmonic distortion (the nasty stuff) and very very low crossover distortion (which makes a big difference). I know, I've designed audio amps with both types. As in designed from the ground up for commercial pro-audio sale. Graham |
#19
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MOSFET output stage
Jorden Verwer wrote: RichD wrote: Who do MOSFET sound better than bipolar, as an audio amp output driver? The device properties of BJTs are superior to those of MOSFETs in all respects, How about SOA for one you UTTER MORON ? Do you even know what SOA is ? except for offset - there MOSFETs have the advantage. Whether you will actually hear this depends on many more factors. YET MORE INSANE ******** Is this all down to techs not knowing their chops ? |
#20
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MOSFET output stage
Gareth Magennis wrote: "RichD" wrote Who do MOSFET sound better than bipolar, as an audio amp output driver? Well this is probably an urban myth/load of ********, but years ago lots of people were talking about power Mosfets exhibiting different distortion characteristics than BJT's in the same way thermionic valves distort with differening harmonics and sound nicer. Fact or crapology? Fact. Different transfer characteristics. Fundamental device physics. Graham |
#21
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MOSFET output stage
Eeyore a écrit :
Trevor Wilson wrote: "RichD" wrote Who do MOSFET sound better than bipolar, as an audio amp output driver? **Non-sequitur. If you're saying that MOSFET outputs sound better, they don't. As a device, operating at typical bias currents (say) 10-50mA, MOSFETs exhibit VASTLY more THD than BJTs. Only when bias currents are elevated (around 0.5A - 1A) do MOSFETs exhibit THD characteristics which are almost as good as BJTs. MOSFETs are very tough, have an exceptional ability to deliver high power, high frequency audio (and RF), but distortion is very high. They require lots of Global NFB in order to operate linearly. MOSFETs do not sound better than BJTs. At best, they can sound as good. All things being equal. With the required amount of feedback (which isn't rocket science - just good design) they have no trouble meeting VERY low THDs such as one I designed with 0.0008% THD @ 1 kHz. They sound better because of the predominance of 2nd harmonic distortion and almost complete absence of 3rd and ditto up the range AIUI with even and odd harmonics. Uhhh. Please explain how you obtain even distortion products from a symmetrical (suppose paired mosfets) push-pull. Any symmetrical function produces odd (and no even) harmonics. :-) ...unless you used single ended output stages. -- Thanks, Fred. |
#22
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MOSFET output stage
"Randy Yates" "Phil Allison" **Non-sequitur. If you're saying that MOSFET outputs sound better, they don't. As a device, ** Same old red-herring ******** from know nothing Wilson. It is totally irrelevant how DEVICES behave on their own. Only when they are properly configured and suitably biased in a complimentary output stage can performances be compared. operating at typical bias currents (say) 10-50mA, MOSFETs exhibit VASTLY more THD than BJTs. ** UTTER ******** !!! No it's not. ** Yes it is you pathetic, know nothing MORON, When configured in typical amplifier topologies, THD is vanishingly small at all power levels and with minimal bias current. That may be true, but only because of the negative feedback that Trevor referred to. ** Bull. The basic device IS more nonlinear. ** Irrelevant. Can't you read - dickhead. ..... Phil |
#23
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MOSFET output stage
"Eeyore" wrote in message ... Gareth Magennis wrote: "RichD" wrote Who do MOSFET sound better than bipolar, as an audio amp output driver? Well this is probably an urban myth/load of ********, but years ago lots of people were talking about power Mosfets exhibiting different distortion characteristics than BJT's in the same way thermionic valves distort with differening harmonics and sound nicer. Fact or crapology? Fact. Different transfer characteristics. Fundamental device physics. Graham Well in that case the OP's question is thus answered, as far as I can tell. It sure is noisy in here. Gareth. |
#24
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MOSFET output stage
"Gareth Magennis" Well this is probably an urban myth/load of ********, but years ago lots of people were talking about power Mosfets exhibiting different distortion characteristics than BJT's in the same way thermionic valves distort with differening harmonics and sound nicer. Fact or crapology? ** Audiophool crapology - repeated parrot fashion, ad nauseam. The THD residual of even the simplest topology, lateral mosfet audio amplifiers is vanishingly small. Sub the threshold of audibility. ..... Phil |
#25
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MOSFET output stage
"Gareth Magennis" Well in that case the OP's question is thus answered, as far as I can tell. ** It can never be answered. Since it was a UTTERLY meaningless TROLL. You pathetic fool. ..... Phil |
#26
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MOSFET output stage
"Phil Allison" wrote in message ... "Gareth Magennis" Well this is probably an urban myth/load of ********, but years ago lots of people were talking about power Mosfets exhibiting different distortion characteristics than BJT's in the same way thermionic valves distort with differening harmonics and sound nicer. Fact or crapology? ** Audiophool crapology - repeated parrot fashion, ad nauseam. The THD residual of even the simplest topology, lateral mosfet audio amplifiers is vanishingly small. Sub the threshold of audibility. .... Phil Not if you clip them like you might a valve amp for example. Would a Mosfet amp clip more "nicely" than a BJT amp? I'm thinking driving bass speakers. Is this what some of these "audiophools" or pehaps PA guys are getting at by saying they sound better? Gareth. |
#27
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MOSFET output stage
"Gareth Magennis" "Phil Allison" Well this is probably an urban myth/load of ********, but years ago lots of people were talking about power Mosfets exhibiting different distortion characteristics than BJT's in the same way thermionic valves distort with differening harmonics and sound nicer. Fact or crapology? ** Audiophool crapology - repeated parrot fashion, ad nauseam. The THD residual of even the simplest topology, lateral mosfet audio amplifiers is vanishingly small. Sub the threshold of audibility. Not if you clip them like you might a valve amp for example. ** Only ****ing half-wits listen to clipped audio from a home hi-fi. Would a Mosfet amp clip more "nicely" than a BJT amp? ** No. Any more ****wit MOSFET myths you want to give an airing here ? Imbecile. ...... Phil |
#28
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MOSFET output stage
"Phil Allison" wrote in message ... "Gareth Magennis" "Phil Allison" Well this is probably an urban myth/load of ********, but years ago lots of people were talking about power Mosfets exhibiting different distortion characteristics than BJT's in the same way thermionic valves distort with differening harmonics and sound nicer. Fact or crapology? ** Audiophool crapology - repeated parrot fashion, ad nauseam. The THD residual of even the simplest topology, lateral mosfet audio amplifiers is vanishingly small. Sub the threshold of audibility. Not if you clip them like you might a valve amp for example. ** Only ****ing half-wits listen to clipped audio from a home hi-fi. Would a Mosfet amp clip more "nicely" than a BJT amp? ** No. Any more ****wit MOSFET myths you want to give an airing here ? Imbecile. ..... Phil Er, perhaps. Mosfets don't have the same thermal characteristics as BJT's, which are more prone to thermal runaway. So perhaps when you are runing Mosfets hard, there is some kind of compression thing going on which sounds nicer than a BJT amp exploding after clipping a lot. Gareth. |
#29
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MOSFET output stage
Fred Bartoli wrote: Eeyore a écrit : Trevor Wilson wrote: "RichD" wrote Who do MOSFET sound better than bipolar, as an audio amp output driver? **Non-sequitur. If you're saying that MOSFET outputs sound better, they don't. As a device, operating at typical bias currents (say) 10-50mA, MOSFETs exhibit VASTLY more THD than BJTs. Only when bias currents are elevated (around 0.5A - 1A) do MOSFETs exhibit THD characteristics which are almost as good as BJTs. MOSFETs are very tough, have an exceptional ability to deliver high power, high frequency audio (and RF), but distortion is very high. They require lots of Global NFB in order to operate linearly. MOSFETs do not sound better than BJTs. At best, they can sound as good. All things being equal. With the required amount of feedback (which isn't rocket science - just good design) they have no trouble meeting VERY low THDs such as one I designed with 0.0008% THD @ 1 kHz. They sound better because of the predominance of 2nd harmonic distortion and almost complete absence of 3rd and ditto up the range AIUI with even and odd harmonics. Uhhh. Please explain how you obtain even distortion products from a symmetrical (suppose paired mosfets) push-pull. If you're such an expert, built one and see for yourself. And use LATERAL mosfets designed for audio. TWIT. Graham |
#30
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MOSFET output stage
Gareth Magennis wrote: "Eeyore" wrote Gareth Magennis wrote: "RichD" wrote Who do MOSFET sound better than bipolar, as an audio amp output driver? Well this is probably an urban myth/load of ********, but years ago lots of people were talking about power Mosfets exhibiting different distortion characteristics than BJT's in the same way thermionic valves distort with differening harmonics and sound nicer. Fact or crapology? Fact. Different transfer characteristics. Fundamental device physics. Well in that case the OP's question is thus answered, as far as I can tell. It sure is noisy in here. It is indeed, with a whole bunch of nutcases spouting nonsense. It's a fact that 'open loop' with no NFB, a mosfet output stage will indeed distort more than a bipolar one, but the distortion characteristics are different. Put some gain on the front and close the loop and the mosfet wins every time (admittedly requiring more overall NFB but it can take it). That 0.0008% THD amp I mentioned, you could not see ANY vestiges of crossover distortion on an Audio Precision analyser output, and what you could see was mainly 2nd harmonic. Oh and its THD floor is 0.0007%, so doubtless the amp was rather better than the display said. Graham |
#31
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MOSFET output stage
Gareth Magennis wrote: Not if you clip them like you might a valve amp for example. Would a Mosfet amp clip more "nicely" than a BJT amp? Not really. I'm thinking driving bass speakers. Is this what some of these "audiophools" or pehaps PA guys are getting at by saying they sound better? I know of no 'PA' amps currently using mosfets. Everyone wants cheap these days and bipolars are cheaper. Graham |
#32
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MOSFET output stage
Gareth Magennis wrote: Er, perhaps. Mosfets don't have the same thermal characteristics as BJT's, which are more prone to thermal runaway. So perhaps when you are runing Mosfets hard, there is some kind of compression thing going on which sounds nicer than a BJT amp exploding after clipping a lot. Competently designed BJT amps don't 'explode'. It's not difficult, but the Chinese haven't quite mastered it yet. Graham |
#33
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MOSFET output stage
"Gareth Magennis" "Phil Allison" Not if you clip them like you might a valve amp for example. ** Only ****ing half-wits listen to clipped audio from a home hi-fi. Would a Mosfet amp clip more "nicely" than a BJT amp? ** No. Any more ****wit MOSFET myths you want to give an airing here ? Imbecile. Er, perhaps. ** Wot a glutton for punishment we have here - folks. Mosfets don't have the same thermal characteristics as BJT's, which are more prone to thermal runaway. So perhaps when you are runing Mosfets hard, there is some kind of compression thing going on which sounds nicer than a BJT amp exploding after clipping a lot. ** Another 100% ****wit MOSFET myth............. Go away - you IDIOT !!! ....... Phil |
#34
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MOSFET output stage
"Eeyore" wrote in message ... Gareth Magennis wrote: Er, perhaps. Mosfets don't have the same thermal characteristics as BJT's, which are more prone to thermal runaway. So perhaps when you are runing Mosfets hard, there is some kind of compression thing going on which sounds nicer than a BJT amp exploding after clipping a lot. Competently designed BJT amps don't 'explode'. It's not difficult, but the Chinese haven't quite mastered it yet. Graham The point is that when people prefer one amp over another it may not be easy to tell technically what it is they prefer. If a Mosfet amp compresses the bottom end slightly over a BJT, for example, this might in the long term be a nicer sounding amp. Maybe absolutely nothing to do with crossover distorion, linearity, feedback blah blah blah. Gareth. |
#35
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MOSFET output stage
"Phil Allison" wrote in message ... "Gareth Magennis" "Phil Allison" Not if you clip them like you might a valve amp for example. ** Only ****ing half-wits listen to clipped audio from a home hi-fi. Would a Mosfet amp clip more "nicely" than a BJT amp? ** No. Any more ****wit MOSFET myths you want to give an airing here ? Imbecile. Er, perhaps. ** Wot a glutton for punishment we have here - folks. Mosfets don't have the same thermal characteristics as BJT's, which are more prone to thermal runaway. So perhaps when you are runing Mosfets hard, there is some kind of compression thing going on which sounds nicer than a BJT amp exploding after clipping a lot. ** Another 100% ****wit MOSFET myth............. Go away - you IDIOT !!! ...... Phil No, this is good fun, and you might eventually tell me why my supposition is untrue. Gareth. |
#36
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MOSFET output stage
"RichD" wrote in message
Who do MOSFET sound better than bipolar, as an audio amp output driver? Who do? That's voodoo! |
#37
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MOSFET output stage
"Eeyore" wrote in
message Kevin McMurtrie wrote: In article , Damon Hill wrote: RichD wrote in news:b78fc9c2-fe9c-444c-8ac5- : Who do MOSFET sound better than bipolar, as an audio amp output driver? They do? Seems like it's possible to design good amplifiers either way. --Damon Exactly - zero difference in quality capabilities. It's usually a matter of impedance matching. Silicon transistors have a fixed loss around 0.5 volts. MOSFETs have a resistive loss inversely proportional to their voltage rating. That usually makes MOSFETs less expensive for low impedances and transistors less expensive for high impedances. TOTAL AND COMPLETE GARBAGE. Agreed. Actually, what Kevin said is the exact reverse of generally accepted practical knowledge. Bipolar is generally more efficient when the impedances get really low. MOSFETs were trendy for a while, but most new power amp designs seem to have bipolar outputs. |
#38
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MOSFET output stage
wrote in message
On Sep 17, 6:12 pm, RichD wrote: Who do MOSFET sound better than bipolar, as an audio amp output driver? MOSFETS HAVE WIDER BANDWIDTH ,less phase shift , lower odd harmonic distortin. on and on. Not in any relevant way for audio power amps. |
#39
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MOSFET output stage
"Eeysore" I know of no 'PA' amps currently using mosfets. ** Huh ???? All those hundreds of thousands of MOSFET audio power amps made since the mid 1980s have not justs disappeared you know - power amps made by H-H & Harrison Electronics plus C-Audio in the UK , Perreaux and ZPE of NZ, Australian Monitor and ARX (still in full production) and Jands here in Aussie - plus many other less well known brands. The majority are STILL in use, maybe looking just a bit the worse for wear. Even in the UK - Chevin Research ( based in Yorkshire) A-series amps are all lateral mosfet designs. http://www.chevin-research.com/products_a_series.php ...... Phil |
#40
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MOSFET output stage
"Gareth Magennis" ** Bugger off - ******. Gareth Magennis wrote: If a Mosfet amp compresses the bottom end slightly over a BJT, ..... blah, blah , blah ..... |
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