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Finished this build about a month and a half ago and figured I'd make a post here. Did the Mojotone 6G16 Brown Vibroverb kit.
I purchased the Mojotone kit minus speakers. Separately I ordered a pair of Weber 10A125's. I also found a seller online that makes repro faceplates and ordered up the proper Vibroverb style plate.
It took me about a week to complete. Background: I'm not an electronics or amp tech. Just an enthusiastic hobbyist. I've previously built several pedals and a 5E3 kit. I decided to do the Vibroverb because I wanted a challenge and it's not something I have in my amp lineup.
The kit comes with no instructions at all. Just a layout diagram and a schematic. This was my first time building an amp of this layout. I did find that Mojotone had a video series on Youtube where they go through a build of their Deluxe Reverb kit and I used that as sort of a guide as the chassis layouts are very similar so the same principles apply.
THE GOOD:
The cabinet construction is top notch. It's easy to see why Mojotone is such a popular supplier of cabinets around the industry. The whole thing is made of pine and it's completely flawless. Tolex and grill cloth look spot on. The whole construction appears to be vintage accurate. Same goes for the chassis. It's heavy gauge steel and perfectly made. I have owned an actual vintage 1960 Super and honestly the Mojo cabinet and chassis look identical to what was in that vintage amp.
Transformers appear to be well made. (internet says they're wound by Heyboer). Fiber eyelet board is also of high quality. The components are all carbon comp resistors. The caps are orange drop. No, they're not the primo Sozo or F&T's but I can't see it being an issue.
My aftermarket faceplate also looks PERFECTLY vintage accurate and the holes lined up EXACTLY with the chassis!
THE BAD:
To be frank, Mojotone has work to do on their attention to detail when supplying these kits. I ran into missing pieces multiple times. One resistor was missing due to a miscount on the kit. Later I discovered I was missing another resistor entirely. It was on the layout and schematic but it wasn't in the actual parts inventory at all. They also didn't include screws to mount the cap board or reverb pan. And the final kicker was when I went to mount the chassis I discovered that the nuts to secure the chassis strap bolts were missing.
Also, they are really chintzy with the supplied wire. It's funny because in their DR build video their tech manager says, "oh you can make your leads extra long if you want there's lots of wire. I've got a shop full of the stuff." No. Do not be careless with your lead lengths as you will run out of wire. I was very judicious with my leads and I still ran about 8" short of blue wire. I had JUST enough red, green, and brown wire. The only wire I had a little extra left on was yellow. And like I said, I was careful with how much I used. I did very little trimming of the leads in final assembly.
CHALLENGES:
-It took some thinking and figuring on how to drill and mount the boards (they're not pre-drilled).
-Despite the Mojo design being modified from the original Fender schematic to add an adjustable bias pot, I had trouble getting the bias current up high enough. I replaced the 15K bias resistor with an 8.2K and with the pot maxed I still can only get it up to 42ma which ends up being about 60% of plate dissipation.
- Reverb was noisy at first. Ended up reading to try flipping the reverb tank 180 degrees inside the bag and it worked!
- The mounting holes through the cabinet for the chassis straps are NOT pre-drilled. Not the end of the world but it took some thinking to figure out the best way to drill them in the right place to get the chassis to hang where it should.
VERDICT:
In the end, it sounds GREAT! The amp is very warm and harmonically rich. The reverb might be the best I've ever heard. It's darker sounding that your typical BF reverb and doesn't get overly splashy and incoherent when turned up. The reverb is rich and warm. The tremolo also sounds fantastic because how can you beat tube driven bias wiggle trem?
And finally, here's the pictures of the finished product!
I purchased the Mojotone kit minus speakers. Separately I ordered a pair of Weber 10A125's. I also found a seller online that makes repro faceplates and ordered up the proper Vibroverb style plate.
It took me about a week to complete. Background: I'm not an electronics or amp tech. Just an enthusiastic hobbyist. I've previously built several pedals and a 5E3 kit. I decided to do the Vibroverb because I wanted a challenge and it's not something I have in my amp lineup.
The kit comes with no instructions at all. Just a layout diagram and a schematic. This was my first time building an amp of this layout. I did find that Mojotone had a video series on Youtube where they go through a build of their Deluxe Reverb kit and I used that as sort of a guide as the chassis layouts are very similar so the same principles apply.
THE GOOD:
The cabinet construction is top notch. It's easy to see why Mojotone is such a popular supplier of cabinets around the industry. The whole thing is made of pine and it's completely flawless. Tolex and grill cloth look spot on. The whole construction appears to be vintage accurate. Same goes for the chassis. It's heavy gauge steel and perfectly made. I have owned an actual vintage 1960 Super and honestly the Mojo cabinet and chassis look identical to what was in that vintage amp.
Transformers appear to be well made. (internet says they're wound by Heyboer). Fiber eyelet board is also of high quality. The components are all carbon comp resistors. The caps are orange drop. No, they're not the primo Sozo or F&T's but I can't see it being an issue.
My aftermarket faceplate also looks PERFECTLY vintage accurate and the holes lined up EXACTLY with the chassis!
THE BAD:
To be frank, Mojotone has work to do on their attention to detail when supplying these kits. I ran into missing pieces multiple times. One resistor was missing due to a miscount on the kit. Later I discovered I was missing another resistor entirely. It was on the layout and schematic but it wasn't in the actual parts inventory at all. They also didn't include screws to mount the cap board or reverb pan. And the final kicker was when I went to mount the chassis I discovered that the nuts to secure the chassis strap bolts were missing.
Also, they are really chintzy with the supplied wire. It's funny because in their DR build video their tech manager says, "oh you can make your leads extra long if you want there's lots of wire. I've got a shop full of the stuff." No. Do not be careless with your lead lengths as you will run out of wire. I was very judicious with my leads and I still ran about 8" short of blue wire. I had JUST enough red, green, and brown wire. The only wire I had a little extra left on was yellow. And like I said, I was careful with how much I used. I did very little trimming of the leads in final assembly.
CHALLENGES:
-It took some thinking and figuring on how to drill and mount the boards (they're not pre-drilled).
-Despite the Mojo design being modified from the original Fender schematic to add an adjustable bias pot, I had trouble getting the bias current up high enough. I replaced the 15K bias resistor with an 8.2K and with the pot maxed I still can only get it up to 42ma which ends up being about 60% of plate dissipation.
- Reverb was noisy at first. Ended up reading to try flipping the reverb tank 180 degrees inside the bag and it worked!
- The mounting holes through the cabinet for the chassis straps are NOT pre-drilled. Not the end of the world but it took some thinking to figure out the best way to drill them in the right place to get the chassis to hang where it should.
VERDICT:
In the end, it sounds GREAT! The amp is very warm and harmonically rich. The reverb might be the best I've ever heard. It's darker sounding that your typical BF reverb and doesn't get overly splashy and incoherent when turned up. The reverb is rich and warm. The tremolo also sounds fantastic because how can you beat tube driven bias wiggle trem?
And finally, here's the pictures of the finished product!
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