[Powdered Toast Man]

My kit will take about 6 weeks to process and get shipped. Faceplate is in the mail. Just ordered a pair of 10A125's from Weber yesterday.

Now I sit and wait for stuff to show up.

 

[Powdered Toast Man]

I finished my Vibroverb 6G16 build about a month ago. It's a Mojotone kit, sounds absolutely killer. I'm still thinking about what I'm going to do for some branding on the faceplate. I'll likely go with "Pandemic Sixty-Three" or "Pandemic Vee-Two" or something like that. I had a plate made for my Super build, posted elsewhere in this thread. Anyhoo, here are a few pics...

BTW, I'm considering selling this one if anyone's interested.

Cheers.

What have you got going on right here? I've just run into a wall with my Mojotone kit. in this spot the layout calls for a 470 ohm resistor and they did not include one in the kit. It's not even on the parts inventory. I mistakenly put a 470k resistor there and didn't realize there was a problem until I went to wire in the tube sockets and found I'm short a 470k for V5.

So now I'm at a stand still because I'm missing a 470 ohm resistor. Could have been finished the build this weekend but now I'm going to have to wait 2 weeks for Mojo to mail the part.

 

[HarpBoy]

View attachment 376010

What have you got going on right here? I've just run into a wall with my Mojotone kit. in this spot the layout calls for a 470 ohm resistor and they did not include one in the kit. It's not even on the parts inventory. I mistakenly put a 470k resistor there and didn't realize there was a problem until I went to wire in the tube sockets and found I'm short a 470k for V5.

So now I'm at a stand still because I'm missing a 470 ohm resistor. Could have been finished the build this weekend but now I'm going to have to wait 2 weeks for Mojo to mail the part.

You've got a good eye. I ran into the exact same problem, although I didn't try to put a 470k in there. I scavenged a couple 800r and a couple 100r resistors I had and jerry-rigged 454r to keep me going. I emailed Mojotone about the part being left out of the kit but knew it was going to be a while before I got a replacement so went ahead with testing and then buttoned it up so I could play the thing. At some point I'll put the proper replacement in there but it works fine as it is so I'll do it when I have another reason to pull the chassis.
Don't know about your experience, but I was missing several parts from my kit. I chalked it up to Covid and cut them some slack.

Great amp otherwise, and I'm still a fan of Mojotone. I built their 5F4 kit last year, and there were zero issues.

By the way, if you live in my vicinity, I can give you my part I got from them and you can pay me back when you get yours. I live in Whitby, Ontario.

Something else to be aware of is that you're likely going to have to change a resistor to get sufficient bias voltage. I replaced the 15k bias resistor between the adjust pot and ground with a 6.8k, another guy changed the 1k on the bias board to 2.2k. Something to be aware of and prepared for. I've got a couple spare carbon comp 6.8k's on hand; that was one of the parts they'd shorted me on.

Cheers.

 

[Powdered Toast Man]

You've got a good eye. I ran into the exact same problem, although I didn't try to put a 470k in there. I scavenged a couple 800r and a couple 100r resistors I had and jerry-rigged 454r to keep me going. I emailed Mojotone about the part being left out of the kit but knew it was going to be a while before I got a replacement so went ahead with testing and then buttoned it up so I could play the thing. At some point I'll put the proper replacement in there but it works fine as it is so I'll do it when I have another reason to pull the chassis.
Don't know about your experience, but I was missing several parts from my kit. I chalked it up to Covid and cut them some slack.

Great amp otherwise, and I'm still a fan of Mojotone.

By the way, if you live in my vicinity, I can give you my part I got from them and you can pay me back when you get yours. I live in Whitby, Ontario.

Something else to be aware of is that you're likely going to have to change a resistor to get sufficient bias voltage. I replaced the 15k bias resistor between the adjust pot and ground, another guy changed the 1k on the bias board to 2.2k. Something to be aware of and prepared for. I've got a couple spare carbon comp 6.8k's on hand; that was one of the parts they'd shorted me on.

Cheers.

Aaaah so they know about this problem and are still shipping the kits without the 470 ohm resistor anyway. Awesome.

Mine was missing an 82k resistor. Same as you they're shipping it to me but I found a guy locally who was able to hook me up. Got the 470 ohm off him today too.

I guess the 6G16 is still a pretty new kit for them. Still you'd expect their attention to detail would be better given how many kits they supply to the market.

Other than the missing parts I found they're pretty chintzy with the wire. I didn't waste any and I BARELY had enough red. I was about 8 inches short of blue.

 

[Powdered Toast Man]

I'm just about ready to test

 

[Powdered Toast Man]

Few more pics of my build.

 

[Powdered Toast Man]

Hmm... problems. First power up did not go right. I did the pre-testing and everything seemed fine. Voltages were where they should be etc. No snaps or pops or smoke or smells. When I put the power and preamp tubes in is where something is wrong. Rectifier and V8 are fine. V7 the tube isn't functional (no filament glow, no heat) and none of the preamp tubes are on. Tried swapping the power tubes to make sure it's not a DOA tube - it works fine in V8.

 

[Paul Running]

none of the preamp tubes are on

Check the voltage from the filament supply and track it from the source to the filaments...DVM set to low volts AC.

 

[Powdered Toast Man]

Check the voltage from the filament supply and track it from the source to the filaments...DVM set to low volts AC.

Aaaah it works! Problem solved. I was checking connectivity between all the points and it gave me signal at all points. So I took a closer look at the filament wires and started kinda prodding things. Noticed a bit of clicking as I shook the leads between the power tubes (since that seemed like the likely problem point). Sure enough there was a solder joint that was missed on one of the filament wires. The wire was in the hole on the pin but without the solder it wasn't making proper contact so all the tubes beyond that point weren't getting power.

Hit that solder joint and then fired it up again. All tubes glowing! Plugged it in and we got ourselves an amp!

 

[Powdered Toast Man]

Man.... I gotta say I can't recommend a Mojotone kit to anyone. The cabinet is great. The chassis is great. Most of the components are great. But what's not good at all is their care and attention in supplying the kits. I was missing one resistor (they miscounted). Ok so they're sending me that one. Then I discovered I'm missing a second resistor - except this one is actually missing from their own parts inventory list for the kit. It's on the schematic and the layout but it's not in their parts list. Now they have to send me that too. NOW in final assembly I realize that they didn't include the friggin nuts to secure the chassis strap bolts! I can't mount the bloody chassis! So now I have to go run around to the hardware store trying to find the right nuts because I'm not waiting weeks while they mail me 4 nuts. Just absolutely not impressed.

Anyway, the amp works. @HarpBoy as you predicted the bias range is way too shallow. I have go looking for maybe a 10k resistor to swap out the 15k in there.

Also, I'm getting a lot of 60 cycle hum buzz in the reverb when it's turned up any. I tried unplugging the reverb send and receive RCA cables and it stops. So I'm pretty sure it's either the cables or the tank. Gotta play around with it to see if I can quiet it down.

 

[Powdered Toast Man]

My build is complete! After a number of hurdles I have it all together and working. The amp is pretty quiet at idle (just a little background hum). I got the reverb circuit quieted down by turning the tank around 180 degrees in the bag. It's still a reverb circuit so it's never going to be completely silent but it's pretty good. I picked up some 10k and 8.2k resistors for the bias circuit. I ended up going with the 8.2k and I still can only get the bias current up to 42ma which is roughly 60% plate dissipation. I have a new set of 6L6's on order and those should arrive next week. I requested they send me a pair that runs on the hotter side so hopefully they'll bias better than these tubes.

Amp sounds really good! Tone is rich and warm. The reverb might be the best I've heard on an amp. You can really crank the reverb up and it doesn't get all splashy and incoherent like most BF amps I've played. It's got a darker sounding reverb - which is totally awesome! The tremolo is super strong and nothing beats bias wiggle trem. Turned up the amp is loud but not stupid loud. Overall it's a really great sounding package!

Here's my photos:

 

[HarpBoy]

My build is complete! After a number of hurdles I have it all together and working. The amp is pretty quiet at idle (just a little background hum). I got the reverb circuit quieted down by turning the tank around 180 degrees in the bag. It's still a reverb circuit so it's never going to be completely silent but it's pretty good. I picked up some 10k and 8.2k resistors for the bias circuit. I ended up going with the 8.2k and I still can only get the bias current up to 42ma which is roughly 60% plate dissipation. I have a new set of 6L6's on order and those should arrive next week. I requested they send me a pair that runs on the hotter side so hopefully they'll bias better than these tubes.

Amp sounds really good! Tone is rich and warm. The reverb might be the best I've heard on an amp. You can really crank the reverb up and it doesn't get all splashy and incoherent like most BF amps I've played. It's got a darker sounding reverb - which is totally awesome! The tremolo is super strong and nothing beats bias wiggle trem. Turned up the amp is loud but not stupid loud. Overall it's a really great sounding package!

Here's my photos:

That's a nice looking amp, Toastie! For what it's worth, I'm running my 6L6s at about 42ma as well, although the 6.8k will give me the option of cooking them a little more if I want to. When my reverb is engaged, I also get some hum/buzz (seems to have both 60 and 120hz noise), but I substituted a 5751 in v4 to tame things a bit. I'm never gonna be running the verb anywhere near 10 anyway. At about 4-5 is where the noise max is more or less acceptable for mic'd gig use, and the depth is about the most I would want anyway. Maybe that's just the nature of this beast.
You'll probably agree that it was a fun/challenging build, with a great outcome in general. The 6G16 is a great sounding amp.
I built Mojotone's 5F4 kit last year, and that kit was perfect, except for a JJ 6L6 that was DOA. I think that the combination of COVID making their operations somewhat challenging along with the 6G16 being a new kit for them left a few things lacking. At the end of the day, I'd still buy another setup from them if I wanted to build another amp, and would recommend their stuff to others with a few heads-up.
Congrats on your Vibroverb!

 

[Powdered Toast Man]

That's a nice looking amp, Frenchie! For what it's worth, I'm running my 6L6s at about 42ma as well, although the 6.8k will give me the option of cooking them a little more if I want to. When my reverb is engaged, I also get some hum/buzz, but I substituted a 5751 in v4 to tame things a bit. I'm never gonna be running the verb anywhere near 10 anyway. At about 4-5 is where the noise max is more or less acceptable for mic'd gig use, and the depth is about the most I would want anyway. Maybe that's just the nature of this beast.
You'll probably agree that it was a fun/challenging build, with a great outcome in general. The 6G16 is a great sounding amp.
I built Mojotone's 5F4 kit last year, and that kit was perfect, except for a JJ 6L6 that was DOA. I think that the combination of COVID making their operations somewhat challenging along with the 6G16 being a new kit for them left a few things lacking. At the end of the day, I'd still buy another setup from them if I wanted to build another amp, and would recommend their stuff to others with a few heads-up.
Congrats on your Vibroverb!

Thanks man! Your feedback was helpful so thanks for your earlier posts!

I actually had some email dialogue with Andy Johnston over at Mojotone. I told him about my experience with the build and listed our the problems I had with it and my advice to improve their kit. He actually thanked me for providing actual constructive feedback to them because that's something useful he can pass along to those department managers who are responsible. Andy was really nice to deal with and he was quick to respond with any issues or questions I had.

I absolutely would build another Mojo kit. They've got a great selection. And despite my issues they stand behind their product and will make anything right.

The 6G16 sounds AMAZING (especially with these Weber speakers). I've used it in band rehearsals and everyone loves it. It absolutely is going to see gig use.

And to note, the new 6L6 tubes arrived and biased up no problem. I've got them running at about 46ma which is a bit under 70%.

I have the same issue with the reverb. I find it's very dependent on where the amp is physically located. It's pretty quiet in some places but in my jam room the reverb gets noisy when turned up. Nature of the beast. I've read that a spring reverb tank is kind of like a big single coil pickup in that it easily picks up RF noise.

 

[HarpBoy]

Thanks man! Your feedback was helpful so thanks for your earlier posts!

I actually had some email dialogue with Andy Johnston over at Mojotone. I told him about my experience with the build and listed our the problems I had with it and my advice to improve their kit. He actually thanked me for providing actual constructive feedback to them because that's something useful he can pass along to those department managers who are responsible. Andy was really nice to deal with and he was quick to respond with any issues or questions I had.

I absolutely would build another Mojo kit. They've got a great selection. And despite my issues they stand behind their product and will make anything right.

The 6G16 sounds AMAZING (especially with these Weber speakers). I've used it in band rehearsals and everyone loves it. It absolutely is going to see gig use.

Funny, I'd actually compiled my observations about the kit in an email to Andy as well, but never heard back from him. I wasn't critical, tried to strike a constructive, helpful tone. At any rate, I have found them helpful and responsive when I've reached out to them, and am a fan of those guys overall. They know they're stuff, respond promptly and allow us to build stuff that would otherwise be kind of challenging to source ourselves.
BTW, if you're interested in adding the vintage-correct cup washers to your back panel screws, I have about fifty on hand. PM me your address and I can drop some in the mail to you.

Cheers, and enjoy that amp. It's a good one. I plug my American Performer tele into mine regularly.

 

[MiSt]

I've been working away on a 6G16 brownface Vibroverb clone build. A very busy board in some places, but I went slowly & carefully and I think it's all right.
View attachment 236116
One thing that threw me for a loop though is the treble pots the build asks for. 350K with a 70K tap. Huh???
Wtf? Of course you never notice that sort of thing until you're well into the build.......and none of your regular suppliers sells anything like that. I'm still looking for some. Guess I'll switch and work on the other side of the amp for a while.

Great build… can you please advice where to get the brass grounding plate. I am building 6G16 too and want to use brass grounding. Many thanks

 

[Lincoln]

well.......I purchase brass shim stock, 0.020 thick, and I have a friend who's a tin-basher (sheet metal mechanic). I had an original plate that I bought on eBay, and using that as a template, he copied the angle, cut & bent the shim stock to sizes I provided him. So I end up with grounding plate "blanks" in common lengths that I mark & drill for what ever amp I'm building.