I have been futzing around with this amp for MONTHS between trips to our farm in Tennessee where we’re building (ahem, I am building) our forever home on 87 acres having fired the thieving, lying, incompetent contractor 18 months ago. It’s coming along. I got back 2 weeks ago, leave again in 3, hope to have a certificate of occupancy by September. I decided I wanted to have TWO inputs to this amp which required a rotary switch - yeah, I could’ve just gone with a DPDT bat-handle one but, well, you know, I wanted different, and some symmetry to the front. It took a while to get the right switch - one I bought through ePay was broken internally so outputs didn’t match, returned it, then second I got through Mouser was for a PCB mount - I couldn’t get the part numbers straight so I finally spoke with tech folks at Mouser, then Grayhill, Mouser again sending a PICTURE of what I was looking for electrically to them and they special ordered one. The original parts order went out in October, then some parts took longer to arrive than others. Knobs and some internal parts and feet and such were from Chicoms, which take weeks to a month sometimes. Building the maple chassis for it was interesting, and the top is 3/16” carbon steel which I blackened after drilling the several holes for tubes, switches, trim pots and such. I had originally wired it for a 5Z3 tube ‘cause I had a few on hand already, redid it for a 5ar4 (not a lot of work, just replaced the socket), actually bought the wrong OPTs for it (5-20-3.5U, not 5k, then STILL bought the wrong OPTs, H-507S which don’t have the same frequency response as the 5-20-x models and I’ll sell on ePay, have H-20-7U’s coming in shortly - I used to own some Sansui equipment in the 70’s, I like the way they sound), so I finally figured what the heck, got the final wiring together this morning, hooked it up to some desktop speakers and plugged an iPhone 13 (I use for BT streamer and keep much of my music on) while WW2 was on in the background on the Hitler channel (Memorial Day ritual). On its side so I can check voltages and temperatures. It. Sounds. Amazing. I’m using a $20 JJ 5AR4 rectifier right now - with cheapest sets of SOVTEK 6SN7 equivalent tubes and EH300b PTs while it burns in just in case anything burns UP - and some crappy little speakers, too. I think this was a good investment of my time and money. I have several Mullard, Amperex Bugle Boys, Telefunken and other GZ34/5AR4 tubes from the 50’s as well as same period 6SN7 and 6F8G tubes to choose from and a pair of EML 300b’s I’ve used in a Tektron 2A3/50 amp for about a year now so once I button it up and plug it into my main speakers, this will be a lot of fun while I work on my NEXT project - parts already collected with the correct OPTs this time - a pair of 2A3 monoblocks based on Level 5 2A3 SE design. Very tempting to buy a metal base Mullard circa 1955 from what I hear about them… THANK YOU @Skunkie. This has been fun. Challenging too. Not as challenging as buliding a house, doing all the interior finish carpentry, finishing my man cave/audio room, but it has been nearly as much fun.

Intro: Stephe's original BOM called for the EDCOR trafo (as our EU friends call them, and it's easier to type) which developed a short. Note where the 50+ volt bias is coming off the 6.3 VAC winding. Enter the Hammond 273BX which was wired differently (from Mouser.com'(http://Mouser.com)s page) Red/Yellow "High Voltage" is reference ground for Red/Red, NOT 50 VAC. 50 VAC comes off the GRN/YEL for Filament #2 and does go to ground in the bias circuit. HERE is my question: From the Hammond 374BX data sheet (https://www.mouser.com/datasheet/2/177/300-951115.pdf)(https://www.mouser.com/datasheet/2/177/300-951115.pdf): First: IGNORE Filament #1 (refer to PDF if any questions), there are only two LV outs on this model. Second, the 50 VAC comes from between the two RED HV lines, Red/Yel goes to ground. Third: YEL/YEL goes to rectifier heater, CT Yel/Blk not used. On the 274BX the Grn/Yel line between the two GRN 6.3 VAC is for 50 VAC. Does it (Grn/Yel) go to ground for the 374BX as reference ground for the GRN/GRN leads to the 6SN7 heaters?? If the answer is obvious, and yes, please affirm. I've looked at several dozen different schematics for tube amps from Aiken, Robinette, Valvewizard to Stephe and many others and see a YUGE variation in how different amps/trafos get wired so this has me confused enough to post before I finish wiring what I've started. Thanks in advance. Norm