Just going through the BOM and I ran into a parts issue with the 2SD2081, which is obsolete. The 2SB1259 is available currently.
Looking to the suggested alternate parts 2SD2014/2SB1257, the 2SD2014 seems to also be out of stock at reputable sellers. Digikey provides an alternate part to the 2SD2014 of KSD1408YTU, which has a complimentary part of KSB1017YTU (still available).
Will the KSD1408YTU/KSB1017YTU be acceptable alternates for the 2SD2081/2SB1259?
Looking to the suggested alternate parts 2SD2014/2SB1257, the 2SD2014 seems to also be out of stock at reputable sellers. Digikey provides an alternate part to the 2SD2014 of KSD1408YTU, which has a complimentary part of KSB1017YTU (still available).
Will the KSD1408YTU/KSB1017YTU be acceptable alternates for the 2SD2081/2SB1259?
Thank you for the offer! I've already got boards on order, or I'd take you up on it. I'm hoping someone smarter than me can help provide a suggestion on a good substitute since the primary and backup options are now obsolete, and not available through trusted channels. I'm sure others will benefit from learning what a good substitute will be. I'd rather not go the ebay route. Been burned too many times trying that.
Hfe on the KSD1408YTU/KSB1017YTU are a bit low. The TIP122/TIP127 which was recommended earlier in the thread have a better Hfe at min 1000 and is also a Darlington like the 2081/1259. The TIP part should work just fine since it sits in the PSU, aka, no music signal going through, and is therefore less critical.. one could say .. as long as it is within reasonable spec.
Pinout is compatible
https://www.diyaudio.com/community/threads/pass-hpa-1-what-do-we-know.300060/page-22#post-7264222
Pinout is compatible
https://www.diyaudio.com/community/threads/pass-hpa-1-what-do-we-know.300060/page-22#post-7264222
I use MJF122G and MJF127G from ON Semi with very good results.
Hi,
is it possible to increase gain ? I need a few more to properly drive my amp...
Thanks
Damien
is it possible to increase gain ? I need a few more to properly drive my amp...
Thanks
Damien
Reducing the feedback will increase the gain. (Increase R27 to reduce the feedback.)
It's going to change the sound as well, though. You might want to reduce the loading on the output stage (R17/R19) as well, but I'm only guessing here.
It's going to change the sound as well, though. You might want to reduce the loading on the output stage (R17/R19) as well, but I'm only guessing here.
I have an extra 5 quantity HPA-1 boards, with button boards on hand from JLCPCB that I plan to offer up for sale. I also have the now difficult to find FQP3N30/FQP3P20 on hand along with the replacement for the unobtainable darlingtons (TIP122/TIP127) noted above on hand to include to help builders get past the hard to find parts. I will eventually post these up in the Swap Meet for sale, but if anyone wants to reserve one, just PM me. Total cost with the included parts (2qty pairs FQP3N30/FQP3P20 + 1qty pair TIP122/TIP127) should be $25 plus shipping. Due to the size of the boards, shipping within US should be reasonable, but I suspect international shipping will be kinda high.
EDIT - I can also likely provide the heat sinks if that helps, but I'm still working on confirming if I have the correct parts on hand.
EDIT - I can also likely provide the heat sinks if that helps, but I'm still working on confirming if I have the correct parts on hand.
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Not sure if it's 100 times expensive.
30usd for matched 2SA970BL / 2SC2240BL 2 channels.
Expensive than KSA/KSC.
30usd for matched 2SA970BL / 2SC2240BL 2 channels.
Expensive than KSA/KSC.
Yes, I did. Sound is more detailed, but less slam. You have to change resistors to take in account the different Vgs.
Both variants have their pro and cons, for me no winner.