Gut and refurb old ss combo

[Lt. Bob]

Also, just FYI @Lt. Bob your Deluxe Reverb is fixed bias. Your little 18w Marshall TMB is cathode biased. You can set the bias on your Deluxe. Your 18w was set by me and you can't do jack shit about it!

Well, you can, but please don't.

I had to fine tune the cathode bias resistor on your 18w. The schematic value had your tubes running at like 130% and that will kill them fast. I got it set right at 95-100% with EL84s which is right where you wanna be with a cathode bias amp.

I remember you telling me that ...... seems like their designer wouldn't have missed that.

Just shows you can simply accept whatever they tell ya' when building kits.

[Greg_L]

I remember you telling me that ...... seems like their designer wouldn't have missed that.

Just shows you can simply accept whatever they tell ya' when building kits.

It seems like the kit designers stayed pretty faithful to the old school 18w schematic. Not a problem for the most part, except our current wall voltages are way higher than they were in the 60s, and tubes are way less robust. We're starting with about 15 more volts straight out of the wall. 10% more voltage across the board gets pretty big by the time you get to the big voltages being used by the output stage. It's too much for some of the component values they used in the 60s.

[Greg_L]

Well I didn't quite get as far as I wanted to today. I could have but fuck it. Tomorrow is another day.

Did I mention I hate shielded wire? I think I did, but I'll say it again - fuck shielded wire. Today was about eight tedious hookups of prepping and connecting shielded wire....along with all the front panel to board connections.



The backside of the treacherous front panel.


But all that's done now. All that's left is to run my filter cap grounds to their respective grounding points and connect those to the floating ground rod.

[Greg_L]

Okay gents, this here is the last wire to connect.


That last wire is part of my grounding experiment. It will ground the screen supply node and the bias supply at the main reservoir ground. This is all high current stuff and I don't want it mixed in with delicate preamp grounds.


And the janky front panel has been riveted and knobbed. I ended up going with the smaller "pedal knobs" after all. They just seem to look better to me against the narrow-ish panel and shitty lettering. But it all fits and worked out so far. All of my jacks and controls are nicely spaced along the front panel.


And with that, the amp part of the build is complete. Everything is connected. Nothing more to do at this point but fire it up.


Here it sits on the ground. I've got a fucking ton of clean up to do before I can move into power up mode.


Yall have flattered me with your "tidy" comments. Well, here is some tidy for you. The aftermath.



So yeah, now I'm gonna double-check every everything, and clean up this fucking mess so I can have a clean slate to start the power-up process.

[Lt. Bob]

[Tadpui]

Woohoo! Best of luck, and may the gods of electrons smile down upon your new amp on its maiden voyage.

[rayc]

Look at the "mess" again: the screw drivers are pointing in one direction and most of the small wire offcuts are in one spot. The only untidy thing I see is that the wire stripper, snips & needlenose pliers are open.

[Greg_L]

Look at the "mess" again: the screw drivers are pointing in one direction and most of the small wire offcuts are in one spot. The only untidy thing I see is that the wire stripper, snips & needlenose pliers are open.

They're spring loaded so they default to open.


Anyway....first stages of powering on happening right now.

I had a blunder right from the get go.

I hooked up the variac and light bulb limiter to slowly add some juice to the Assman. And then, nothing. I wound the variac up to around 70 volts AC. That should get something happening, but nothing happened. I had no voltage coming out the other side of the power transformer. Nothing. No pilot light, no heater voltage, no secondary voltage, no bias voltage. Nothing. But the fuse didn't blow and the light bulb limiter stayed off so there's no dead short. There's just nothing. Shit, I'm thinking I have a bunk power transformer.

So I disconnected the secondary leads and the bias lead and gave it about 70 volts again. Now I'm reading voltage on those open wires, good voltage, so WTF? I hooked them back up to their respective spots, fed it another 70 volts, and now things are working. I must have had a shitty solder connection. Now I've got a dim pilot light. I've got voltage hitting the rectifier, I've got negative voltage coming out of the bias, and I'm getting rectified DC at the first filter caps. I slowly wound it up to full wall voltage. 490 volts DC (with no tubes in it) at the reservoir caps. -63 volts DC for bias. A full 6.5 volts AC for the heaters. This is all very good! And no fires, smoke, or shorts....yet. I'm a little concerned about these fucking turrets. I mentioned they fight the solder. I'm hoping I don't have anymore bad connections.

Anyway, everything on the "off" side of the standby switch is working fine. I'm letting the first filter caps leak down and the next test will be with standby set to play and we'll introduce the juice to the rest of the amp. Fingers crossed. The Assman cometh.

Oh, just FYI...all of this initial stuff is done with no tubes in the amp. Voltages will be artificially high with no tubes drawing power, but that's okay. We don't wanna sacrifice tubes.

[Greg_L]

Okay! Everything downstream has gotten some high voltage. All the B+ nodes and their respective filter caps have been brought up to full power. I'm seeing expected voltages where I expect to see it. I'm comfortable enough with what I'm seeing to move onto installing some tubes and seeing if it makes sound.

Dinner, then tube time.

[rayc]

ONE solder dud - that's a pretty good rate.

[Greg_L]

ONE solder dud - that's a pretty good rate.

Well so far. There could be more waiting to fuck my Assman in the ass.

[Tadpui]

Well so far. There could be more waiting to fuck my Assman in the ass.

That would be unacceptable! It is Tender, after all.

[Greg_L]

Well I'm happy to report that IT IS ALIVE!!!!!!!






And it makes sound. I did my voltage testing, set the bias, and ran a 1khz sine wave through it and looked at it on the scope. Everything looked good and healthy so I plugged in a guitar and my wide open no cab bench speaker. It works. It amplifies guitar. I can't make any tone judgements on a brand new build with a single speaker not even in a cab face down on a table, but it fucking works and that's all that matters right now.

So a few things have me especially giddy at the moment....
1) My grounding scheme seems to work great. So far this thing is so quiet I couldn't even tell it was on until I had it cranked.
2) Blackfacing the bias circuit is a win. This thing would be way off with the stock schematic non-adjustable 1962 spec bias setup.
3) I made this happen. This isn't a kit. I didn't buy it ready to assemble. I sourced each and every part and figured out a way to make it work.
4) It didn't catch on fire.

Big win for the Assman today.

[Tadpui]

This great, man. Well done, and I'll save the champagne for when it's finished. But I totally agree, those are definitely points to be proud of. Your own design, your own build from scratch. That's definitely something to be proud of! And now this prototype will be worth a fortune once the Tender Assman goes into mass production

[Greg_L]

This great, man. Well done, and I'll save the champagne for when it's finished. But I totally agree, those are definitely points to be proud of. Your own design, your own build from scratch. That's definitely something to be proud of! And now this prototype will be worth a fortune once the Tender Assman goes into mass production

Haha thanks!

I'm actually kind of surprised there isn't a kit market for this particular model of Fender amp. You can pretty easily find kits for most of the Bassmans, from the Tweed era to Silverface. And almost all of the Blackface era of amps are available in kit form. But the "Blonde/Brownface" years are nonexistent. I'm not sure why. They're not particularly difficult. Any of the reverb/tremolo Blackface amps are exponentially harder to deal with than this Bassman circuit. I don't get it. Maybe there just aren't many famous users of these particular amps. I know for me Brian Setzer is one of the reasons I chose this amp to build. He uses a 1963 Blonde/Brownface Bassman. Now I have absolutely no illusions of being able to sound anything like him, but if it's good enough for him, it's certainly good enough for me.

[JD01]

Amazing. Well done.

[rayc]

I know for me Brian Setzer is one of the reasons I chose this amp to build. He uses a 1963 Blonde/Brownface Bassman. Now I have absolutely no illusions of being able to sound anything like him, but if it's good enough for him, it's certainly good enough for me.

I don't know if he was using one on the Cats tour in Sydney in September 81but he sounded GREAT.

[JD01]

3) I made this happen. This isn't a kit. I didn't buy it ready to assemble. I sourced each and every part and figured out a way to make it work.

This is really cool.

[Greg_L]

Amazing. Well done.

Thanks dude.

I'm very...how do yall say over there? Chuffed? I think chuffed is the right word. Still far to go, but just making guitar sounds and no melted parts is a huge win for a brand new build.

I don't know if he was using one on the Cats tour in Sydney in September 81but he sounded GREAT.

He sounds great all the damn time. Of course he's an amazing guitar player and could probably make anything sound great. But he chooses a 6G6B Bassman to do his thing. That's a pretty strong endorsement in my mind.

[WhiskeyJack]

Yesssss.

good job man!!! Nothing exploded. You win. Pretty excited to hear how this turned out!!!