Hoffman 6G15- Brown-face-style

[tdvt]

I just powered up the newest project, gathered a few parts years back & that was as far as it got.

The traditional Fender layout for the 6G15 never appealed to me, so I decided to build it in a brown-face style to be paired with my Blonde Showman.

I used Doug's board, adapted to radial filter caps, & built it into a Brown-face Princeton chassis. I also changed the control order to something that made more sense to me.

As the chassis was pretty roomy, I was able to put all the transformers inside the chassis; an Antek toriodal PT, the little output transformer & the reverb driver.

A tip of the hat to Tubeswell for all his various posts regarding grounding schemes to help mitigate noise in these units. As a result, I built this one totally isolated from the chassis, with the only connection to power ground through a Merlin humblocker. It is absolutely silent into the Princeton Reverb test mule. (silent in a good way :)


Cabinet next..

[bmccowan]

I have an original brownface 6G15 and I built one with the idea of selling the original. But I am not thrilled with either of them. I'm interested in learning what you came up with following Tubeswell's guidance.

[tdvt]

Well,

I distilled any number of things mentioned by Tubeswell (& others), into a ground plan & he was the one who specifically mentioned the Merlin Humblocker. (I had Valve Wizard article saved but didn't think to look there)

In the end. I built this completely isolated from the chassis except for the circuit ground to chassis through the hum-blocker.

• In/out/foot-switch are completely isolated from the chassis mounting holes
• Pot shells are at chassis ground potential but the pot circuit grounds run to a bus wire.  I have readily adopted Sluckey's flying bus wire technique for the controls & use it in everything.
• Input to V1/P2 & .047/V2/P7 connected with shielded cable (as per Doug) + Dwell wiper to V1/P7 shielded cable.
• Input jack-end of the bus wire, B+ ground & board ground all connect to the inboard-side of the hum-blocker, then the one ground to the chassis (same bolt as the toroidal shield)

End result is very quiet with no hum or noise into the guitar amp.

I would like to streamline the hum-blocker physical layout but used stuff on hand for this one (temp-ed in Orange Drop to be changed out) as it could be smaller. Merlin suggests using a 1-piece FWB for the diodes

PS  Noticed that the Merlin drawing shows 25A diodes, he states elsewhere a FWB of 3A-8A is adequate. Drawing not updated...?