Hi Fuzzhead, spotting some minor things : 1. Can't find the 560pF connected to IC1 6 - 7 on the original schem. 2. Missing 1k res in the Level 2 to output 3. Pots annotation. No volume and masters on original schem, only level.
I'll second everything in Elantech's comment above, and add one more thing: the anode of D1 should hit G18, not I18. Other than that, you can call this one verified, and it is a VERY good Plexi emulation (such that it's as frustrating to dial in as an actual Marshall 1959, LOL).
The output volume is curiously low. Even with the level maxed, it's not much above unity. As such the 1k resistor on Level lug 2 isn't necessary.
Oh, forgot to mention: per the comments at FSB, if you want to raise the gain, try a higher value for the feedback resistor between pins 6&7 of IC1 (the 2k7 resistor at W16-Z16). Somewhere around 20k seems to be optimal, and the closest to an actual Plexi amp.
This comment has been removed by the author.
ReplyDeleteHi Fuzzhead, spotting some minor things :
ReplyDelete1. Can't find the 560pF connected to IC1 6 - 7 on the original schem.
2. Missing 1k res in the Level 2 to output
3. Pots annotation. No volume and masters on original schem, only level.
Thanks for the layout!
Cheers
Thanks for taking a look. I'll take a closer look when I get home for the weekend.
Deletehello, where is the output? congratulations for the layout, I will assemble soon.
ReplyDeleteI'll second everything in Elantech's comment above, and add one more thing: the anode of D1 should hit G18, not I18. Other than that, you can call this one verified, and it is a VERY good Plexi emulation (such that it's as frustrating to dial in as an actual Marshall 1959, LOL).
ReplyDeleteThe output volume is curiously low. Even with the level maxed, it's not much above unity. As such the 1k resistor on Level lug 2 isn't necessary.
Oh, forgot to mention: per the comments at FSB, if you want to raise the gain, try a higher value for the feedback resistor between pins 6&7 of IC1 (the 2k7 resistor at W16-Z16). Somewhere around 20k seems to be optimal, and the closest to an actual Plexi amp.
Delete