Hi Stephe. Just opened up my R300 to see what model I have. Unfortunately it's not the one you are doing your power supply mod to. There are no resistors on the rectifier tubes and only one diode so I assume it's wired completely differently than the one you have. When I got it I did replace all of the chinese tubes with Russion ones. The rectifiers are Sovtek 5U4G's. With the bias pots centered I'm getting exactly 400v. The voltage does ramp up kind of quickly but not an instant hit to 400v. Like the R8, it has the crazy grounding wires going all the way up to the headphone jack and the power wires are non twisted from the power supply to the power switch. Not sure what your plans are to look at doing R8 style wiring, resistor and cap mods for the R300. I did buy some Gold Lion 5AR4 tubes if I start having problems with my Sovteks. Here is a picture of what my power supply are looks like.

I see you have rewired the rectifier tubes in your power supply video. Thanks for the great videos.

Hi Stephe. Thanks very much but after a good nigh sleep I figured it out in about 2 minutes with my multimeter. Right speaker board was not powered. Back up to the front end. One resistor in the wrong spot from the split mod. Fixed it in 30 seconds. Did the whole front end on one sho last night. Turns out I’m not as young as I use to be. :)

Hate to say it’s too late to recheck my parts. Was trying to work the problem backwards. Starting with the symptoms and what would cause what I’m seeing.

And Stephe. I was wrong. I am an idiot. I thought decades of turning bags of parts, twisted wire, pots, caps, switches and valves into absolutely beautiful sounding guitar amps would allow me to follow some really great videos from you and turn a lump of coal into gold. I was wrong. Undoing other peoples crappy parts and bad designs is something I've never had to do. Hope this can get figured out or I'll just have to stick to following Leo Fender and his great designs and keep putting them in the hands of other musicians.

Yes. I think I'm going to pass on this one. I don't have the test equipment to even see what it's doing and a don't know the GNFB system on this amp at all. Everything else made sense once I saw what she was doing in the video and explained some of the theory. I'm a old school Fender Tube amp builder of components on an eyelet board and hand wiring absolutely everything so the work on the tube sockets and wiring was easy to follow. I have never in my tube amp building put a single component on a PCB, so this was very educational in that respect. But I do no mods to anything Fender designed and wired. Mainly because I wanted to keep my amps true to the original. But undoing stupid wiring and component quality that makes no sense from our Asian builders is no issue for me at all.

Ok. I’m stupid. I totally do not understand what Stephe is doing with the GNFB parts she talks about in her video. They obviously make a difference. Is the a mod to the circuit somewhere, or replacing existing components somewhere.

I'm finding some things very similar to building my old tube amps, but my guitar amps are all built on 1950's and 1960's architecture, nothing modern in them at all, and for almost all I have wiring diagrams, so I'm purposely not making any kind of modifications to them. Just building the eyelet boards with new components and proper wire dressing. Got to love Fender and the folks that knew how to build stuff right back then. Modifying what the Chinese built, well that's were your help is indispensable. Thanks again. Love taking a break from guitar amps for a while.

Thanks much. Putting my order together to start the power tubes and power board. Wish me luck. Just finished my A12 and it sounds great. Thanks Stephe!!!!

Skunkie. I just finished my A12 upgrades. It sounds great pushing my Klipsch speakers with a subwoofer. Now I'm waiting for new tubes and the Gold Lion Rectifier tube you suggested. The work was straight forward. Navigating the parts was still my most challenging issue since I'm not a electrical builder from scratch. But eventually I found the right caps and resistors. Thanks. Now on to my R8😀

I understand completely. I love the fact that someone is doing this at all. Unfortunately I’ve been spoiled by building kits where all the parts came with the kit. But I’ll keep plugging away as far as I can doing upgrades. Thank you for what your doing.

This is all I'm looking at so far for parts. One very small step at a time for me.

Is the Bias board the same as the Power Supply board? I'm watching the video where you are changing the resistors and the two caps on the power supply board. You call out the resistor values but not the caps. I'm trying to avoid tearing into mine until I have enough parts to make a Mouser order and not get killed with shipping. And I suck at reading schematics. BOM's, wiring diagrams, and calling out values works for me unfortunately. I'm understand what you are doing, but it's identifying the parts that's my downfall. wish me luck when I crack mine open and slowly start upgrading.

Unfortunately the BOM that someone posted was missing the single Metal Film Resistors - Through Hole 2watts 430Kohms 5%. $8 shipping for a .36 cent part.

Would these in the project photo be 22uf 400v Orange Drop cap?

Just opened my A12 up to start working. Have your photo and the one of the first things I noticed is it looks like the two caps from the pre-amp sockets to the driver sockets are orange caps. Not the Chinese 224K400. Do you change these as well? Maybe the one on the on off switch as well.

Found the link with part numbers. Only 2 were out of stock, but the list provided great descriptions down to the tolerance on resistors and caps so I got my whole order in. Now let’s see if this pig will fly

Thanks Carl. I actually just did the same thing and found the pre-amp input disables my R8 volume control in favor of the pre-amps volume, so I know there was some logic built into the inputs. I just was not sure about how the others might be different.