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Old 5th December 2016, 06:46 PM   #11
2 picoDumbs is offline 2 picoDumbs  Australia
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Quote:
Originally Posted by generg View Post
and keep in mind that I use the "old" Sony frontend, there is newer version in the Sony II thread with slightly changed resistors and possibly better sound as Nelson was told when he got some feedback from people.
Naah that was different application.
In my opinion since your choice is the same as mine it must be the best choice. Hahahaha
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Old 5th December 2016, 07:15 PM   #12
generg is offline generg  Germany
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And I tell you I am deeply impressed by the clarity and finesse of sound!

So Nelson real XA25 must be heavenly!
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Old 5th December 2016, 07:19 PM   #13
needtubes is offline needtubes  United States
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Quote:
Originally Posted by generg View Post
...so here comes my Hockey Puck Puzzle.....
This is similar to what I have modeled, except for the following:

1. No degeneration resistors anywhere
2. Different "coupling" of the driver to the outputs like in the UGS/UP which avoids capacitors in the signal path, but might make bias touchy
3. No cascode on the JFETs
4. IRF610/9610 MOSFET drivers instead of the Toshiba parts (too afraid to test with my precious Toshibas)

The model, for what its worth, looks fantastic. With luck, I will be able to find time to cobble this together some time in the next month...

Now, the important question for generg: How does it sound? Edit: you were four minutes earlier than me.

Last edited by needtubes; 5th December 2016 at 07:28 PM.
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Old 5th December 2016, 07:26 PM   #14
2 picoDumbs is offline 2 picoDumbs  Australia
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Generg
Do you have any prototype pictures? Zen Mod is mostly interested in observing porn.
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Old 5th December 2016, 08:59 PM   #15
generg is offline generg  Germany
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I refuse to send porn through my devices.....:-))

I will have a look!
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Old 6th December 2016, 04:52 AM   #16
nr12 is offline nr12  Germany
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I refuse to send porn through my devices.....:-))

I will have a look!
There is a porn, errrr, private mode in all browsers.
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Old 6th December 2016, 06:02 PM   #17
lhquam is offline lhquam  United States
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In post #130 Pass XA25? I discussed bias circuits for the output fets. There is an LTSpice simulation comparing 3 bias circuits for an IXTN40P50P operating between 25C and 75C with 24V rail voltages, and 1.3A (approx) bias current.
  • Constant Voltage Bias
  • Thermistor Controlled Constant Current Bias
  • Opamp Servo Constant Current Bias
The plots show Vgs and Id for the FET vs. Temperature. As expected the bias current increases with temperature for the Constant Voltage circuit.

The Thermistor Controlled Constant Current circuit tracks very well with the "ideal" Constant Current Servo.
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File Type: jpg IXTN40P50P-bias-XXX.asc.jpg (167.5 KB, 928 views)
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Old 6th December 2016, 07:07 PM   #18
2 picoDumbs is offline 2 picoDumbs  Australia
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I sssume that simulation is done with thermistor at exact same temperature as mosfet.
Generg's is mounted on heatsink.
Is it possible to simulate the effect of mounting the thermistor in different locations.
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Last edited by 2 picoDumbs; 6th December 2016 at 07:22 PM.
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Old 6th December 2016, 08:19 PM   #19
generg is offline generg  Germany
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Thank you lhquam! Very usefull to know that the Thermistor Controller System can do well. To show this in this way is so valuable.

Quote:
Originally Posted by lhquam View Post
In post #130 Pass XA25? I discussed bias circuits for the output fets. There is an LTSpice simulation comparing 3 bias circuits for an IXTN40P50P operating between 25C and 75C with 24V rail voltages, and 1.3A (approx) bias current.
  • Constant Voltage Bias
  • Thermistor Controlled Constant Current Bias
  • Opamp Servo Constant Current Bias
The plots show Vgs and Id for the FET vs. Temperature. As expected the bias current increases with temperature for the Constant Voltage circuit.

The Thermistor Controlled Constant Current circuit tracks very well with the "ideal" Constant Current Servo.
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Old 6th December 2016, 11:29 PM   #20
lhquam is offline lhquam  United States
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Sorry for my previous post. I am not sure now it got sent to this thread.
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