Amp build thread #2: Super Reverb

[clintj]

Just got the first two boxes of parts for my next build: blackface Super Reverb, circuit AB763. I need to open them up and check the inventory against the packing list, but first I have a dentist appointment.

[Dru Edwards]

Looking forward to this, Clint. You got it from the same retailer as last build?

[clintj]

Yup. Inventory looks good so far, only missing the power transformer and cabinet which should be here next week. This is definitely a complex beast compared to a tweed. I'll be taking my time with this one for sure. Looks like I should order a bias probe for my multimeter tonight for when I power it up later.

[Tone Gopher]

Originally Posted by clintj

Yup. Inventory looks good so far, only missing the power transformer and cabinet which should be here next week. This is definitely a complex beast compared to a tweed. I'll be taking my time with this one for sure. Looks like I should order a bias probe for my multimeter tonight for when I power it up later.

Just add 1 ohm resistors between the output sockets and ground, and put test jacks on the back panel. Set your multi-meter to read voltage and it'll give you a direct read of current (mA).

Details: Tie pins 1+8 together, connect 1 ohm resistor between 1+8 and ground. Run wire from each 1+8 to red panel jack; run wire from ground to black panel jack. Iterate for each output tube or tube pair.

Set DVM to voltage and insert probes to monitor voltage drop across reference resistor. V=RI >> mA across resistor translates directly to mV. Iterate for each tube to read bias current.

[clintj]

Thanks for the tip. I had seen a few people do that mod, but I plan on building a few more amps and a bias probe will come in handy later. My band's rhythm guitarist's amp is starting to need a retube too, and it'll come in handy for that as well.

Got a little bored last night and this morning, so I built up the chassis as far as I could. Installed jacks, pots, sockets, OT, filter choke, and the reverb driver. The OT is larger than the power transformer in my tweed. What a hunk of iron! I had to modify my chassis cradle to fit this thing too. It wouldn't spread far enough apart stock. First round of pics:

[moon]

Exciting I love the smell of roisin in the morning.

[clintj]

Originally Posted by moon

Exciting I love the smell of roisin in the morning.

It smells like vintage tone!

Working through the main eyelet board now, about 1.5 hours in and a quarter done. I envy the people that can build these in the supposed "time to complete" listed, but I'm having fun.

[clintj]

Six hours spent building up the main board and filter cap board. Time to put it aside until tomorrow and give my hands and eyes a break. Tomorrow I'll go over it again making sure I didn't miss any connections, the solder joints look good, and then clip all the extra component leads.

[clintj]

The board looks like it checks out against the layout diagram and the schematic, and some pics of an original 60's Fender I found online. Whew!

I ran about 3/4 of the heater wiring today, and the Fedex guy dropped off my cabinet and power transformer today. That was quick - wasn't supposed to be here until Tuesday. I ordered some more wire today too; I may have cut the leads from the board a little long and used it up faster than anticipated. Still got a foot left, but I like having plenty on hand for "oopsies". Later tonight, I'll install the speakers and reverb tank in the cabinet. Time to set this aside until my next weekend after that's done.

[Dru Edwards]

Looks good, Clint. Give your eyes a break. Do you wear goggles when you solder?

[Steve DeRosa]

Don't know what kind of tubes you're using, but I wouldn't put anything but the best in that puppy:

http://www.thetubestore.com/Tubes/JA...JAN-GE-12AX7WA
http://www.thetubestore.com/Tubes/JA...hilips-12AT7WC
http://www.thetubestore.com/Tubes/JA...by-JAN-Philips
http://www.thetubestore.com/Tubes/5A...nalex-GZ34-U77

[clintj]

Thanks. Not yet, but I might need to in a couple of more years. My near vision is not quite what it used to be, but I'm not ready to admit it yet.

The internet is an amazing resource for these projects. I've found great pics of these old amps, and other build threads that really shed light on the easy way to do things. Saves a lot of "oh, I shouldn't have done that".

[clintj]

Originally Posted by Steve DeRosa

Don't know what kind of tubes you're using, but I wouldn't put anything but the best in that puppy:

http://www.thetubestore.com/Tubes/JA...JAN-GE-12AX7WA
http://www.thetubestore.com/Tubes/JA...hilips-12AT7WC
http://www.thetubestore.com/Tubes/JA...by-JAN-Philips
http://www.thetubestore.com/Tubes/5A...nalex-GZ34-U77

It came with a full complement of JJ's, which will get me through initial power up and break in. I do plan on switching to some nice NOS tubes after that. Just swapping to an old GE tube for V1 in my Tweed made a nice difference.

[redir]

That's cool dude keep posting pics. I've eyeballed these kit builds before is that what you are doing? Do you sell these amps?

[clintj]

Originally Posted by redir

That's cool dude keep posting pics. I've eyeballed these kit builds before is that what you are doing? Do you sell these amps?

It is. I'm building a Mojotone kit. You can go cheaper and get a Ceriatone or Weber, but I liked the quality of the Tweed Deluxe I built so I stuck with them. I personally wouldn't start with one of these, I'd go with a simpler amp design first or even some pedal kits. Pedals are good for learning, without the added bonus of lethal voltages.

No, I don't build these to sell. It's a fun hobby for me though. I fit in build time around my work schedule, so it takes me a little while to get through one. I'll be picking it back up this weekend, and posting more pics as I work.