Vintage Mark-style PCB and chassis kit

[Graydon]

View attachment 4522
I’ve noticed that the paint on the chassis hasn’t been holding up as well as I’d like, it’s been coming off with minor handling. A little disappointing, but the metal shop didn’t do a great job centering the graphics anyway. Now I get to figure out a faceplate plan for these!

On my first Dumble clone, I had a print shop screen the labels directly onto the black powdercoated chassis. They complained that it was very difficult to get the screen flat on the chassis because it wasn't perfectly flat but they got it and they looked great. They've also been durable. But it was enough of a warning that I went to separate faceplates for all of my amps after that. The 18W amps get a 1/16" plexi faceplate while the Guytrons get a thin stainless faceplate. These are much easier to print.

 

[Jay Omega]

On my first Dumble clone, I had a print shop screen the labels directly onto the black powdercoated chassis. They complained that it was very difficult to get the screen flat on the chassis because it wasn't perfectly flat but they got it and they looked great. They've also been durable. But it was enough of a warning that I went to separate faceplates for all of my amps after that. The 18W amps get a 1/16" plexi faceplate while the Guytrons get a thin stainless faceplate. These are much easier to print.

Thank you for the insight! I have a friend with a CNC who cut the plywood for the cab, he said he will help with the faceplates. I bought some acrylic and aluminum sheets from a local supplier to test, will hopefully have something to show within the next couple weeks

 

[Fastforded]

Anything in particular you'd like to see? I'm not much of a video production person but I think I can come up with something

Just maybe go over the amp, components, what you've done. Idk, any interesting tech stuff.

I'm not an amp expert but that any looks really sweet. Alot of work and time, just be nice to see it all. And your thoughts on stuff. Maybe any inside info or thoughts you have on this particular amp.

Thanks Jay

 

[Jay Omega]

Been taking a bit of a break on this project, mostly for personal reasons but also waiting to see what happens with the Boogie C+ reissue. Today I cleaned up the pieces from the CNC and test fit came out great

 

[Fastforded]

Been taking a bit of a break on this project, mostly for personal reasons but also waiting to see what happens with the Boogie C+ reissue. Today I cleaned up the pieces from the CNC and test fit came out great

View attachment 5022

Looks great, can't wait to see the finished product

 

[Hoplite22]

Any updates on this ?

 

[Jay Omega]

Any updates on this ?

If you're asking me, nothing to report as I haven't been able to connect with my CNC guy yet. I need to have him cut another box top for me (something got messed up when we programmed the CNC so thank goodness I measured before glue up) and we need to see if we can get a good faceplate solution going.

Beyond that I've just been messing around with the amp, trying different configurations and what not. Right now I'm using it in 60W mode with the TAD redbase tubes and it's sounding great. Overall I'm really happy with the amp, it's the best sounding thing I have.

I also have a new PC coming and I invested in a few good microphones, hopefully I can some good Tonex captures here in the near future for people to try.

 

[rarebitusa]

Been taking a bit of a break on this project, mostly for personal reasons but also waiting to see what happens with the Boogie C+ reissue.

So the rumors of a limited run IIC+ reissue seem to be pretty legit. But if the run is limited to say 200 would you still go ahead with yours?

 

[Jay Omega]

So the rumors of a limited run IIC+ reissue seem to be pretty legit. But if the run is limited to say 200 would you still go ahead with yours?

I know, it's super exciting! If I'd have known this way back when I wouldn't have dumped all this time and money into the project but it was still fun. I wonder which version it will be, DRG short head? I hadn't heard it will be a limited run, seems like a lot of work to sell only a few but I guess that's what they did with the king snake.

I plan to offer kits regardless as I'm nearly done with the project but my advice to most people is going to be buy the reissue. These amps are quite challenging, there are a lot of places for mistakes to be made and I can see someone goofing and not having the equipment or skills to troubleshoot which is endlessly frustrating. The kits likely won't have a strong resale value so maybe not a great investment for folks unless they want to experiment with the circuit variations or plan to keep them forever.

I have enough parts to build eight amps for myself and I had eleven sets made so I'd like to sell at least three. I'd planned to build two for myself from this first run so would ideally sell nine. If the reissue is not limited it's unlikely I'd do another run unless enough people prepaid, in this case I would build four or five for myself.

 

[rarebitusa]

I wonder which version it will be, DRG short head?

Yea that would seem to be a good choice to start with. Gibson is pretty keen on the limited reissue run deal ie: Les Paul reissues, gives them a chance to evaluate the market and then do another limited run later with some other marketing spin. I'd go out on a limb and say pretty much a given this was a Gibson idea.

Kudos to you for doing this... no doubt it was an undertaking. I for one hope you continue to share what you've done TBH it's invaluable knowledge.

 

[Less02]

I know, it's super exciting! If I'd have known this way back when I wouldn't have dumped all this time and money into the project but it was still fun. I wonder which version it will be, DRG short head? I hadn't heard it will be a limited run, seems like a lot of work to sell only a few but I guess that's what they did with the king snake.

I plan to offer kits regardless as I'm nearly done with the project but my advice to most people is going to be buy the reissue. These amps are quite challenging, there are a lot of places for mistakes to be made and I can see someone goofing and not having the equipment or skills to troubleshoot which is endlessly frustrating. The kits likely won't have a strong resale value so maybe not a great investment for folks unless they want to experiment with the circuit variations or plan to keep them forever.

Wait, wait, wait this need to be qualified . WHATEVER Gibson will do as a reissue if there is really one, it will never be as precise as what you have done Jay! The quality of your build is way better than any modern Mesa Boogie. I can garantee if there is a reissue, it will be a modern adaptation of the C+, it will not be a hand built amp as it was back in the 80’s.

I understand completely when you say it is not a project for everyone, being myself in the process of installing your preamp board in my 2B… it is for experienced electronic technicians / engineers or with equivalent experienced tube amp geek! But the result, whatever the market value, is way over anything else. There is so much proud when you use something you built yourself. As you know, I’m the owner of a home made mkIV, it is the only thing I would bring with me in case of a fire, just after my kids and family….

You should definitely keep going with your project don’t hesitate to offer your kit, or else communicate with Boogie and offer them your design as the reissue they are aiming for! You own the real reissue of the mk2c+!

 

[Jay Omega]

Wait, wait, wait this need to be qualified . WHATEVER Gibson will do as a reissue if there is really one, it will never be as precise as what you have done Jay! The quality of your build is way better than any modern Mesa Boogie. I can garantee if there is a reissue, it will be a modern adaptation of the C+, it will not be a hand built amp as it was back in the 80’s.

I understand completely when you say it is not a project for everyone, being myself in the process of installing your preamp board in my 2B… it is for experienced electronic technicians / engineers or with equivalent experienced tube amp geek! But the result, whatever the market value, is way over anything else. There is so much proud when you use something you built yourself. As you know, I’m the owner of a home made mkIV, it is the only thing I would bring with me in case of a fire, just after my kids and family….

You should definitely keep going with your project don’t hesitate to offer your kit, or else communicate with Boogie and offer them your design as the reissue they are aiming for! You own the real reissue of the mk2c+!

Thank you for saying such nice things @Less02! I agree on the reissue, I can't imagine Boogie would ever go back to the construction method of the old Marks as it's so time intensive.

 

[rarebitusa]

From what I remember, the forward voltage is much higher on the Xvive VTL5C1 so it won’t really turn on when used in parallel with the Vactecs. There is also a 750 pF ceramic cap that could’ve failed, the pot switch, or the associated wiring. If you turn the power on to the amp, leaving the amp in standby, pull the treble shift and put it in lead mode. Read the resistance between the vactrol LDR terminals (the side closer to the big power supply electrolytic cap). If it’s reading 1-2k, your LDR is still OK. You should read approx 10M if you push the treble shift back in

Ok I finally got a chance to poke around. Without power, the pot switch appears functional, it is either open or closed (Pulled out) WRT the resistance across its contacts and the push/pull position. Same readings at the switch terminals and across R5. The wiring appears to be intact. With power, the Vactec also appears to be functional according to the test procedure you outlined. Without power, using an LCR meter and the switch open I read ~750pf across C6. The C5 reading was a bit higher ~330pf then the 250pf the schem calls for.

So I'm left scratching my head a bit, this is a simple circuit. Everything else with the amp seems fine.

Hmm, I'm thinking maybe clip in a different cap value across C6 to see if this changes anything? Appreciate any other suggestions?