Mark IIB to IIC+ Conversion

[JD]

I would grab 1 if you are selling

 

[user 41014]

I'd take one too. This would be a great kit build.

 

[Joeyjiggs]

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.

Where did you ground the ldr power supply cap?

 

[Jay Omega]

Where did you ground the ldr power supply cap?

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.

 

[Joeyjiggs]

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.

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

 

[Henz]

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

 

[Jay Omega]

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.

 

[JD]

Great Work

 

[Jay Omega]

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!

 

[Henz]

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!

View attachment 993

I want one when you're finished!! I'll put my order in now!

 

[Jay Omega]

I want one when you're finished!! I'll put my order in now!

Sounds good! A number of folks have reached out about these, once I verify everything is working correctly I’ll be willing to sell them!

 

[Jay Omega]

Got the new preamp board in today, she fits the IIB like a glove!

 

[user 41014]

Got the new preamp board in today, she fits the IIB like a glove!

View attachment 1192

I like the purple

 

[Jay Omega]

Found a couple hours to start working on this, progress thus far:

 

[Henz]

Found a couple hours to start working on this, progress thus far:

View attachment 1195

Whatcha have going on there? Looks nice!

 

[Jay Omega]

Whatcha have going on there? Looks nice!

Thank you! It’s the preamp board I’m going to use to convert the IIB to a C+

 

[Henz]

Thank you! It’s the preamp board I’m going to use to convert the IIB to a C+

Oh. Ok. I thought that was your other build. With two output tubes.

 

[Jay Omega]

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!

 

[RicherHertz]

@Jay Omega its looking great. Any chance of uploading some audio clips when you’re done?

 

[Jay Omega]

@Jay Omega its looking great. Any chance of uploading some audio clips when you’re done?

I can put something together. Any sounds in particular you’d be interested in?