I prototyped an A40 with anything available in my shop at the time ( 5 years ago ) and even though i used BDV 66-67 or TIP142-147 don't remember anymore ( never spared brain cells on Darlingtons ) the results was very promising .
I actually dislike to work with transistors like Tip 142-147 which i cannot read in any of the datasheets that i am aware their audio specs .
So i am thinking of making once more the A40 , as a complete amplifier ( 5 years ago i made only one ch just to evaluate the performance and evaluate the darlington behavior ) but this time use what Sony/ Denon used MN2488 and MP1620 from Sanken ( since i have plenty )
http://www.alldatasheet.com/datasheet-pdf/pdf/168632/SANKEN/MN2488.html
Any comments on that before i start ?
Kind regards
Sakis
I actually dislike to work with transistors like Tip 142-147 which i cannot read in any of the datasheets that i am aware their audio specs .
So i am thinking of making once more the A40 , as a complete amplifier ( 5 years ago i made only one ch just to evaluate the performance and evaluate the darlington behavior ) but this time use what Sony/ Denon used MN2488 and MP1620 from Sanken ( since i have plenty )
http://www.alldatasheet.com/datasheet-pdf/pdf/168632/SANKEN/MN2488.html
Any comments on that before i start ?
Kind regards
Sakis
As i am in the pcb design level can any one suggest if Q5 that is serving as a Vbe is supposed to be located on the main heatsink ?
or simply use huge heat sinks and let it beh
Kind regards
Sakis
or simply use huge heat sinks and let it beh
Kind regards
Sakis
No. Nelson used a rather neat way to prevent thermal runaway. Look at the VBE multiplier and note the diode 3 and r 13. When the voltage across the output emiter resistors this diode and resistor will force the VBE to lower the bias voltage. Note that instead of a small .1uf to 1uf cap across the VBE this calls for a 220uf cap I assume this
is necessary for this network to work.
is necessary for this network to work.
It also gives the front end a moment to stabilize before the bias is present
on the outputs, reducing turn on thump.
😎
on the outputs, reducing turn on thump.
😎
There was no SOA ratings for the power darlingtons on the data sheet I could see. Wouldn't three or four pairs be prudent?
Devices with the original numbers, PMD16K100 and PMD17K100 are available from Solid State Inc. Ratings are Tc 225W @ 50C (yes 50), Max junction temp 200C, Thermal Resistance jc .67C/W, 2nd breakdown begins at about 35V.
Data sheet: http://www.farnell.com/datasheets/1029428.pdf
Data sheet: http://www.farnell.com/datasheets/1029428.pdf
- Status
- Not open for further replies.