For those awaiting the boards delivery, your packages may be tracked here:
https://parcelsapp.com/en/tracking/
use the tracking number (RR................CZ) that I sent everyone in the PM last week.
https://parcelsapp.com/en/tracking/
use the tracking number (RR................CZ) that I sent everyone in the PM last week.
I got the inputs and headphone jack wired up last night... I played a few tracks through my computers headphone output, tonight I will hook it up to my dac and see what she can really do. So far, she sounded great!
I am going to leave the 5K6 resistors in for the 30mA idle current for now. I added the small addition heat sinks as those little black ones got pretty hot without at that current. Now you can leave your finger on them indefinitely, still hot but hopefully nothing to worry about long term.
I am going to leave the 5K6 resistors in for the 30mA idle current for now. I added the small addition heat sinks as those little black ones got pretty hot without at that current. Now you can leave your finger on them indefinitely, still hot but hopefully nothing to worry about long term.
Even the small heatsinks make reliable operation - I have a prototype here that has been safely operating for 15 years. Yes hot, but still within transistor specs.
Did someone recently ordered parts for this preamp from either Mouser or Digikey, if yes can you please share the BOM cart for my reference.
thanks
thanks
This is a 30kHz clipping scope screenshot, to show excellent overload behaviour of this topology and no phase reversal.
Could you kindly share some plots of open loop characteristics (gain and phase) as a function of frequency, for the single ended version ?
Best regards,
Patrick
Best regards,
Patrick
You probably mean loop gain, rather than open loop gain. Loop gain is the characteristics that shows stability margin and feedback reserve. Below please find the loop gain plots. Closed loop gain is 14dB (5x).
70dB at 100Hz and 1kHz, 59dB at 10kHz, 53dB at 20kHz. Quite flat in audio band, so THD vs. frequency is flat as well. The lowest THD depends on matching of JFETs. My measured plots are from stock LSK170C/LSJ74C (no matching, no selection) as they arrived from DigiKey.
Loop gain = feedback
Open loop gain = Loop gain + gain
Loop gain = feedback
Open loop gain = Loop gain + gain
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In your application, Vds doesn't vary much.
So impact on id (similar to Early Effect) is less significant.
Not the case when used as a follower.
Also when matching NJFET to PJFET, the matching only applies to one specific Vds.
Toshiba devices doesn't have this issue.
Patrick
So impact on id (similar to Early Effect) is less significant.
Not the case when used as a follower.
Also when matching NJFET to PJFET, the matching only applies to one specific Vds.
Toshiba devices doesn't have this issue.
Patrick
That's correct. At normal link level, it is negligible. At high level, it is still acceptable.
But, let's not spread any myths about the Toshiba devices. If you look at 2SK170 Id vs. Vds curve at Vgs = 0, there is not much difference from LSK170.
A pair of 2SK170/2SJ74 matched at 12V is still a good match at 9V.
Not the case for LSK/LSJ.
www.diyaudio.com/community/threads/linear-systems-matched-lsj74-lsk170-jfet-pairs-grade-b.321649/post-7035859
Real life measurements.
Other information from post #31 to #37 in the same thread.
And I am simply stating what I measured.
Not trying to sell anything.
Patrick
Not the case for LSK/LSJ.
www.diyaudio.com/community/threads/linear-systems-matched-lsj74-lsk170-jfet-pairs-grade-b.321649/post-7035859
Real life measurements.
Other information from post #31 to #37 in the same thread.
And I am simply stating what I measured.
Not trying to sell anything.
Patrick
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Thank you, I have checked the thread. My conclusion is that it is a non-issue in my Dispre 2-JFET design. Builders may use both Toshiba and Linear Systems parts. I agree that in case of very simple circuits like simple SE stages with resistor load it may lead to much worse parameters. But I do not use such circuits, I am not a fan of ZEN like circuit designs.