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Old 5th December 2012, 11:13 AM   #61
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Quote:
Originally Posted by dadod View Post
The second one, same input voltage.
dado
Hi Dado
you have got great results with hudge dc offset
anyway I like more the first sch but I am more impressed of the second
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Old 5th December 2012, 02:50 PM   #62
dadod is offline dadod  Croatia
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Originally Posted by padamiecki View Post
Hi Dado
you have got great results with hudge dc offset
anyway I like more the first sch but I am more impressed of the second
Yes I know about the offset. I think it was a problem with LTspice models for BC transistors. Here is a simulation with Cordell's models and the offset is a way down. Nice think about this lineamp is that is non inverting.
Damir
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Old 6th December 2012, 05:03 AM   #63
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... Nice think about this lineamp is that is non inverting. Damir
I read that the engineers like to invert the signal
but indeed it is very good lineamp.
what do you think about RIAA section instead of R1C2?
will it have sufficient gain and minimal noise?
asc file would be very helpful
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Last edited by padamiecki; 6th December 2012 at 05:06 AM.
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Old 6th December 2012, 05:22 AM   #64
dadod is offline dadod  Croatia
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Quote:
Originally Posted by padamiecki View Post
I read that the engineers like to invert the signal
but indeed it is very good lineamp.
what do you think about RIAA section instead of R1C2?
will it have sufficient gain and minimal noise?
asc file would be very helpful
I don't think this amp could be used as RIAA amp, but I have to think about it a bit more.
The ratio R1/R9 together with CM's ratio define the gain, as this is a current conveyor.
Damir
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Old 6th December 2012, 06:24 AM   #65
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The gain resistor could be replaced with an RIAA stage, but without offset control you would not get much gain.

However you could easily use this circuit as an active crossover, with the gain resistor split into multiple crossover networks going to different buffers. I think this would be superior to a voltage-drive active crossover, not that I really know anything about active crossovers.
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Old 6th December 2012, 03:18 PM   #66
dadod is offline dadod  Croatia
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To convert conveyor output current to voltage it uses a resistor and that voltage should be buffered against output load. First output buffer I used was JLH buffer with floating cascode. As the cascode transistor it uses JFET and power voltage is limited by used JFETs.
Here I used BJT as floating cascode and this allows higher power voltage to be used and as a consequence higher output voltage with very similar distortion figures.
There are comparison between JFET cascoded buffer with gain of 7 and BJT cascoded buffer, with gain of 9 and the power voltage of +-40 V instead of +-30 V. Input was 1 ppV.
dado
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File Type: jpg FFT comparison.jpg (238.8 KB, 244 views)
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Old 6th December 2012, 03:32 PM   #67
dadod is offline dadod  Croatia
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This line amp could be called "wire with gain" as it has so low distortion(simulated).
Below are FFTs at the output voltages used mostly at listening.
dado
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File Type: jpg FFT-a-BJTcascode.jpg (212.2 KB, 254 views)
File Type: jpg FFT-b-BJTcascode.jpg (212.9 KB, 241 views)
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Old 6th December 2012, 10:36 PM   #68
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Originally Posted by dadod View Post
This line amp could be called "wire with gain" as it has so low distortion(simulated).
Below are FFTs at the output voltages used mostly at listening.
dado
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Old 7th December 2012, 06:43 AM   #69
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Originally Posted by dadod View Post
This line amp could be called "wire with gain" as it has so low distortion(simulated).
Below are FFTs at the output voltages used mostly at listening.
dado
respect,
did you build it already?
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Old 7th December 2012, 07:09 AM   #70
dadod is offline dadod  Croatia
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respect,
did you build it already?
No, not yet.
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