CCS quality can have a major effect on common-mode distortion. For the 'standard' opamp-like power amp the CM-mode distortion has a big contribution from the LTP CCS non-linearity, and no amount of NFB will remove it. A simple tail resistor could be better than a really bad CCS.dvv said:
CCS elsewhere in the circuit are within the NFB loop so probably won't be heard.
How about old fashioned bootstrap CCS to VAS ? These days the capacitor costs more than a transistor CCS so is not the likely choice . Bootstraps are useful when driving MOS FET 's . I have a circuit of a double bootstrap for MOSFET's somewhere . I use a cheap voltage doubler and regulator to do the job and conventional CCS if wanting the last once of MOSFET power . I have found to take the voltage down to main rail level still has advantages if wanting nice clipping ( switch ) . MOSFET have slightly less than 80 % voltage gain typical when used as output stage current amps .
A tail resistor with clean fixed supply is OK . I think I saw someone do a stimulation on this , he was shocked how good a tail resistor was . Common mode rejection was about 90 dB with a tail resistor and 130 dB with the optimum CCS as John showed some time ago . I think most valve circuits never get near to 90 dB .
A tail resistor with clean fixed supply is OK . I think I saw someone do a stimulation on this , he was shocked how good a tail resistor was . Common mode rejection was about 90 dB with a tail resistor and 130 dB with the optimum CCS as John showed some time ago . I think most valve circuits never get near to 90 dB .
The links were to the mobile site for youtube. Deleting the "m." part of the URL makes it look like the "regular"youtube site:
Audiophile Paradise at Tokyo Audio Show
http://www.youtube.com/watch?feature=related&v=vWHqieSrSaQ
News report, about what one would expect. I'd like one of those turntables...
The Vagabond Soles @ Blackbird Studio
http://www.youtube.com/watch?feature=related&v=peCF0gwTWoE
OMG, it's full of diffusers!
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That was actually the last thing that Dave Bowman said before he was sucked into the the monolith.
Yeah, but man, what a ride!
Odd you should mention that, I've just started reading Arthur C. Clarke's "2061: Oddisey Three", the final chapter of the trilogy.
Jeez, when I remember how struck by the original movies I was ... I saw it in March 1971, in New York.
It made a convert of me, of sorts. After that, to this day, I have gobbled up a respectable number of SF books by everybody who was anybody from the '40ies onwards. Always loved that eternal question: what if?
Like Dual (1019 turntable) and Uher (tape deck) made me an audio convert.
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Yes, and Bowman's quarters during his captivity could have used some acoustical treatment, and not just diffusorsYeah, but man, what a ride!
Odd you should mention that, I've just started reading Arthur C. Clarke's "2061: Oddisey Three", the final chapter of the trilogy.
Jeez, when I remember how struck by the original movies I was ... I saw it in March 1971, in New York.
It made a convert of me, of sorts. After that, to this day, I have gobbled up a respectable number of SF books by everybody who was anybody from the '40ies onwards. Always loved that eternal question: what if?
Like Dual (1019 turntable) and Uher (tape deck) made me an audio convert.
But whaddya want: superintelligent aliens can't think of everything.
Exactly one of the tests I want to try. A tail resistor has one big advantage: It's impedance is uniform with frequency.
I feel with a clean supply it works very well . My beloved Hitachi design has a 47 K tail resistor . 7 active devices which could be reduced to 5 if the double VAS was made single VAS and bootstrap CCS if so . Some will tell you bootstraps need nearly 100 % positive feedback to work . 70 % still is usable . 97% as in complimentary feedback pair is a bit high and sometimes needs a series resistor . 94 % is ideal .
The Hitachi I sometimes build is 8 devices + 3 diodes as I use a tail CCS .
Just was sent this ( Thanks Chris ) .
Pythagoras' theorem - 24 words.
Lord's Prayer - 66 words.
Archimedes' Principle - 67 words.
10 Commandments - 179 words.
Gettysburg address - 286 words.
US Declaration of Independence - 1,300 words.
US Constitution with all 27 Amendments - 7,818 words.
EU regulations on the sale of cabbage - 26,911 words
Pythagoras' theorem - 24 words.
Lord's Prayer - 66 words.
Archimedes' Principle - 67 words.
10 Commandments - 179 words.
Gettysburg address - 286 words.
US Declaration of Independence - 1,300 words.
US Constitution with all 27 Amendments - 7,818 words.
EU regulations on the sale of cabbage - 26,911 words
I think that depends mainly on the preamp's drive capability.
There's a reason why I used 50W (bipolar, 75W for MOSFET) devices for my preamp output. You could stack 3 Otala amps, with its ridiculous 6K8 input impedance, and it wouldn't notice. Stack 'em up, Wayne, it's all right, so long as the ultimate impedance the preamp sees is 8 Ohms. It can do even lower, but distortion starts to rise.
I was anticipating it having to drive 3 separate power amps.
But if your preamp has a weedy op amp output, well then you're in trouble.
Nige is one of those people who first design an amp, and then start taking bits and pieces out from it until it stops working - he then quickly inserts back the last piece taken out, and calls it a day.
It is 8 AM locally as I write this, and the very fact that I am writing it proves that the world is still here.
Seems we beat the rap this time.
For the time being, at least unto 12:12 PM 21.12.2012. Just in case, I'll postpone paying the credit card bill, I really don't want to go out poor.
Seems we beat the rap this time.
For the time being, at least unto 12:12 PM 21.12.2012. Just in case, I'll postpone paying the credit card bill, I really don't want to go out poor.
If the output impedance of the preamp is at least 5 times lower than the paralell input impedance ( resistance ) of the two amplifiers it probably will work . One problem that often occurs is if one amplifier is switched off the diode of the input stage be it transistor or valve will cause distortion . Use some cheap speakers to be sure there are no ground loops or worse . Parallel resistance is Rt = A x B / ( B + A ) input A and B that is . I was taught to say it that way because it is derived from 1/Rt = 1/A + 1/B and B + A is from transposition . + being commutative it can be A + B .
It appears the End of the World was arriving by Serbian railways, and is consequently slightly late. However, it will get here, just give it a few million years ...
Or, it may have arrived, walked out of the Belgrade railway station, looked around and thought: jeez, wrong address, I've been here already.
Or, it may have arrived, walked out of the Belgrade railway station, looked around and thought: jeez, wrong address, I've been here already.
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