My first amp build 5E3 Deluxe

[Stone]

I'm really excited about this. I can't believe how simple this is. I should have tried this 15 years ago. Get ready for my own designs.

[Bruce / Mission Amps]

Looks like a MOJO 5E3 kit... yes? no?

[Stone]

Yep, it's a MOJO kit. It's the brand that the amp building workshop I'm attending offers. I wanted my first build to be under the guidance of someone who had done it many times before. I'm hoping that my 20+ years of industrial electronic experience, along with info from books and sites like this, will give me the tools I need to come up with my own unique design.

My next amp won't be a kit

[sportster4eva]

That's it....now you're gonna be hooked!
Lookin good so far! What kind of a cab are you going to put it in?

[Bruce / Mission Amps]

MOJO uses mostly all very good stuff in their 5E3 kit.
The only short comings are having to bolt everything down to the chassis, over voltaging of the tubes with a Russian 5Y3 and using the tiny 16uF/450v power supply caps... the very same caps that get panned by so many "amp gurus" and amp builders who have about zero experience but love to run on and on about nothing.

[Stone]

That's it....now you're gonna be hooked!
Lookin good so far! What kind of a cab are you going to put it in?
__________________

It's a tweed cab that came with the kit. Nothing special, just a pine box covered in tweed.





Bruce,

The Sovtek rectifier gives me about 375 VDC plate voltage. What tube would you recommend to bring it down to the 315 range?

Is it the rectifier or the PT that's the culprit?

Also, what effect will it have on the amp's tone, tube life, etc.?

I'm a complete newbie at amp building and need to pick the brains of people with expertise.

[Bruce / Mission Amps]

It is both the PT (very good PT) and rectifier (Russian) with the MOJO kit.
The Russian 5Y3GT is way too stiff for this amp and using a NOS one will bring the B+ down closer to vintage levels and tone.
Tube life will be extended with a NOS 5Y3GT also.

[Stone]

Thanks Bruce.

[dustinbridges]

I'm about to start my build and I have the same Mojo kit.

The one thing about this kit is that it doesn't come with the brass plate for grounding. I noticed from your pics that your took traditional gounding route. The pots are grounded to their bodies and the circuit board to the pots.

Have you had any issues with hum taking this grouding route?

Also, do you stick with the ground switch or did you go with a standby switch setup?

Thanks

[Bruce / Mission Amps]

It's a tweed cab that came with the kit. Nothing special, just a pine box covered in tweed.





Bruce,

The Sovtek rectifier gives me about 375 VDC plate voltage. What tube would you recommend to bring it down to the 315 range?

Is it the rectifier or the PT that's the culprit?

Also, what effect will it have on the amp's tone, tube life, etc.?

I'm a complete newbie at amp building and need to pick the brains of people with expertise.

If the B+ at the power tubes with the SOVTEK 5Y3GT is 375vdc then they have changed the PT since the last time I looked/worked on one.
It's really only about 20v-25v high but should be OK... just watch the actual 6V6 dissipation at idle and make sure they are not running over 12 watt each.
Try a NOS 5Y3GT anyhow just to see how it sounds.

[Stone]

I'm about to start my build and I have the same Mojo kit.

The one thing about this kit is that it doesn't come with the brass plate for grounding. I noticed from your pics that your took traditional gounding route. The pots are grounded to their bodies and the circuit board to the pots.

Have you had any issues with hum taking this grouding route?

Also, do you stick with the ground switch or did you go with a standby switch setup?

Thanks

The amp is dead quiet as far as hum is concerned.

I used the ground switch. I've thought about changing it to a Standby as I've never had to use the Ground switch.

[calcam]

The only short comings are having to bolt everything down to the chassis,

Bruce, how it this different in your kits?

[Bruce / Mission Amps]

Bruce, how it this different in your kits?

All my chassis are made with PEM nuts pressed into the steel so there are no nut and bolts used.
Well, the only nuts are the four nuts that are really needed screw onto the power tranny studs when installed in the chassis punch out.. there is no other easy way to mount the PT.
Even the tube sockets are mounted with PEM nuts and SEM machine screws.
You just hold the socket above the socket's punch out and feed a SEM screw into the socket tab holes until it catches the thread of the PEM and screw it down. Super simple.
Same for the OT and the eyelet board.

My chassis ground switch is actually a standby switch and is inked to say it is a standby.... plus marked 'On- Off' to match the actual on off switch.

The other thing is that my chassis kit includes a brass plate with tiny little diameter holes in it to attach ground wires (another source of issues with novice builders) and of course my eyelet board is precision laser cut and custom assembled by me (one at a time) with real brass eyelets and I use larger diameter eyelets in areas where experience has taught me to use a larger eyelet (because there are too many wires going into those tiny 1/8" diameter eyelets everyone else uses).

[d. spree]

replying 5 yearrs later

If the B+ at the power tubes with the SOVTEK 5Y3GT is 375vdc then they have changed the PT since the last time I looked/worked on one.
It's really only about 20v-25v high but should be OK... just watch the actual 6V6 dissipation at idle and make sure they are not running over 12 watt each.
Try a NOS 5Y3GT anyhow just to see how it sounds.

Yes I know I'm replying a million years too late but ... my first 5e3 amp build was a tubedepot kit and it ran about 30v too hot - I used an NOS5Y3GT and it immediately fixed that issue and I believe - even though many folks say the rectifier shouldn't change the sound - it sounds better. My Mission build ran just right.