Mark IIB to IIC+ Conversion

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Jay Omega said:
Turns out the “issue” I found with the effects loop seems to be normal, I checked my Mark III and it does the same thing.

There is a small amount of hum / buzz, which I’m hypersensitive to, but when I fire up my Mark III the fan drowns it out, so I don’t think it’s any different from a normal Boogie.

Maybe it’s time to stick the fork in and call this good! I cranked it up today and was able to get really good sounds out of it, I think the only pot tapers that are off are the master volume because I had to use a 250k instead of 100k, and my lead master as I have 4-5x the LDR ground resistance compared to the real deal.
Click to expand...
Where did you ground the ldr power supply cap?
 
Joeyjiggs said:
Where did you ground the ldr power supply cap?
Click to expand...
Back to a ground trace on the power supply board, it's landed next to the wire that bonds the ground traces to a PT mounting bolt. I've never seen how Boogie does this, they may go straight to the PT bolt. My PT has a 50 VAC non center tapped winding, so one side goes to ground lug and the other goes to the power supply board for bias / etc.
 
Jay Omega said:
Back to a ground trace on the power supply board, it's landed next to the wire that bonds the ground traces to a PT mounting bolt. I've never seen how Boogie does this, they may go straight to the PT bolt. My PT has a 50 VAC non center tapped winding, so one side goes to ground lug and the other goes to the power supply board for bias / etc.
Click to expand...
Try grounding it to the 30uf ground I had an issue with hum I swapped it to the ground of the 30uf and it was silent after that
 
That's interesting. The ground leads on power board all go to chassis ground. So why move it to a different ground pad? I'm learning. Thanks for your patience. Jim
 
I did some lower volume A/B testing tonight against a Mark III HRG blue stripe, Mark IVA and a JP-2C. All Boogie amps were setup for 60W by using two power tubes and the four ohm tap with an 8 ohm load. The closest sounding amp is the JP-2C. I prefer the one I built, it sounds a bit more open, clear, and aggressive, and feels a bit more responsive, but they’re really close. All the tubes are different, so that could play a part of course.

Noise wise, the amp was quieter than the III and the IV, and same as the JP-2C so I’m feeling good about converting the IIB thus far. I’m going to do some more testing at higher volumes before pulling the trigger on the IIB.
 
Welp, I took the plunge. Designed a new board for a fab house and hit submit on a prototype order. I probably should've spent more time checking it over, but feeling lazy, we'll see how it goes. Good thing I don't mind purple!

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Made some progress. Looks like I have a ways to go, but it should come together pretty quickly if everything goes OK as I think I have the big stuff addressed already. Hopefully before the weekend is gone I’ll be able to fire it up!

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