Mojotone 18W chassis for combo build - tube orientation

[jimoreilly]

I’m using a Mojotone chassis and faceplates for an 18W combo build. Mojotone says their chassis can be used for the head or the combo version. But when used in a combo cabinet, the chassis is mounted to the back panel - and with the tube sockets on the top of the chassis, the tubes will be positioned horizontally, instead of vertically.

Since many folks have likely built this as a combo, I’m guessing this should not be a problem, but wanted to see what this community thinks.

For what it’s worth, the TubeDepot chassis has the same issue - not sure about Ceriatone, but GDS offers both head and combo chassis, with the combo chassis punched so the tubes hang (down) vertically, as the original Marshall 18W and other combos normally do.

[Bieworm]

It doesn’t really matter. Lots of amps are built with tubes horizontally. Just make sure the EL84 have a retainer. The tubes wont fall out, don’t worry.
But in this case you need a combo cab that’s large enough so the tubes are not in conflict with the speaker. A standard 18 watt combo cab is plenty large
And an air vent on top or a ventilator would extend tube life. Again, a standard 18watt combo cab is equipped for this

The real thing you should worry about is NOT using the schematic and layout from mojo. That’s a guarantee for trouble

[jimoreilly]

Thanks, @Bieworm - I didn’t think it would be an issue, but thought I’d ask.

Regarding the Mojotone comments, I am using their parts kit and turret board; schematically, it will be similar to theirs, but am doing some tweaks based on what I see here and on other sites. Layout (especially grounding) will follow best practices as described by @jmpguitars and others - star grounds, no bussbar on back of pots, etc)

This is a tremolo build, not a TMB build, so lower gain overall and perhaps less worry - but I’ll proceed carefully

[Bieworm]

The tremolo version is nice. The tremolo TMB is nicer! Not that generic overdrive the regular TMB has.. there’s no comparison. It’s a nice and organic low gain amp with a unique and great tone.