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This is complete remake of Cobra mk2 amp from 70s, I was asked to add master volume end effect loop at first, but it finished as full rebuild with added master, buffered effect loop and EF86 channel to existing diagram (copy of Fender Princeton reverb sans reverb ;) )
These amps, cobra is same as riviera 725 from pepco, are cool amp, but very noisey (hum) , with poor tubes layout and heather wiring.
Amps is very quiet now (at idle LOL), very loud for two 6V6 in the output.

If I had to do same job again, I would make a new chassis, it was a hassle to reuse existing one.
As usual, lovely work, Damir. I actually picked up a "Cobra" head from a Songbird garage sale (back when they were Songbird), and keep meaning to rebuild it into something else. Right now, the contenders are brownface Vibrolux, Tremolux, Deluxe, or Princeton. But I'm also wondering about other possibilities. In your experience, is the power transformer capable of powering another 12AX7 on top of the two already in there?
 

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Thanks for kind words Mark . There is definitely enough spare power in that power transformer for your project. I would suggest another chassis, it's easier to build new one than reuse existing one.
 

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This would be my first attempt at something like this. What, in particular, makes reuse of the existing one difficult?
 

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Tubes layout, heater wiring...
I like to start with nice layout, so no unpleasant surprises at the end.
 

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Had a customer bring in a tweed 4X10 blues de-ville that he ultimately wasn't happy with, so we decided to gut it and put in a (pretty close) 5F6A Bassman circuit.

Gutted



De-ville circuit boards




Bassman - circuit board



Heaters!



End of day 1 progress



 

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Man - that Rock-Ola is the bomb! Both clean and dirty...

++++++++++++++

Here is a Trinity (kit) 5E3.

I always wanted one as a kid, but they are rare, at least in my town. Bought the kit last year from Trinity, and finally completed it this past winter. The instructions from Trinity are beautiful and clear, but I struggled to find the time.

I'm using an old 12" '64 Jensen from a Leslie 25 cabinet - the tweed cabinet was made for me, built just like the real ones, with a floating baffle.

Mods include a 1 Meg grid stopper on pin 7 of V2 to calm down the unwanted phase inverter harmonics when pushed hard into OD, and I have a Post PI master volume in mind (Trainwreck type a la Rob Robinette).

Robinettes' page:
5E3 Mods

==========

One other big thing is that I biased the power tubes waaay down from what the stock schematic called for, replacing the 5 watt 250 ohm resistor with a 10 watt 470 ohm resistor.
This puts older softer NOS power tubes in their happy place and puts the bias slightly cool for the new JJ's. The sound is really thick and lovely, tons of nice secondary harmonics, and the amp reminds me of my buddy's tweed that we all coveted in the 1970's.

Pics:







Jensen c12N


I've got some old RCA 12AY7/12Ax7/5Y3 tubes in V1, V2 and V5 (rectifier) and a couple of new JJ's in for power tubes.

This little amp makes me smile every time I plug my old strat in.
 

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I built this amp a couple years ago. It is a Trinity Tramp kit and the cabinet was custom made by yours truly.

I wanted a low watt tube amp that I could play in the basement, something nice that people could use to test out my guitars. At first I was toying with the idea of buying something, Blues Jr or AC15 and making a custom cabinet for it. Then My wife convinced me that I wouldn't be satisfied unless I built the entire amp. So I started my quest for a kit and settled on the Tramp.

The cabinet is Maple and Walnut. The lumber was harvested from a farm only a couple concessions from where we live.

DSC_0492.JPG



DSC_0494.JPG


DSC_0536.JPG

IMG_0983.JPG
 

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Hey fellas, I designed & built this 2x12 for a buddy of mine, and I know it’s not an amp, it’s just the cabinet, I’m currently refinishing his head to match - I’ll post photos when I’m finished with that.

I took apart his Kustom Defender, and reused the Eminence speaker that was in it, and paired it with a Weber Alnico Blue Dog for a super saucy blend.

This was definitely a small challenge given that this is literally the second time I've built an extension cabinet and it's my very first paying customer... any of you guys out there that do this full time, any business pro-tips would be much appreciated! I know I've got a LOT to learn, and the sooner I learn, the better!

The idea started off of a drawing of a cabinet that I (still) want to make out of solid wood, and kind of morphed into something a little different, but boy, am I pleased with how it turned out considering. The face of it is made up of 9 pieces (6 of which are 5/8" spacers for the grill cloth), but the maple accents on the face were planed down to 7/16" to accommodate sitting on top of the excess grill cloth that was wrapped underneath it. The angles were a tad tricky at first, but I think I managed to pin it all down pretty well! All in all it took me 12 hours to build (not including the glue and clamping of the joints for the shell and the 36 hour sit time for the glue to tack up properly), which I thought was pretty good!

I just started doing this on the side with the idea of seeing where it goes... what do you guys think?
 

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Wow very clean build, congrats. And that cabinet is absolutely superb. May I ask what it is finished with?
Hey - that’s my amp build! Thanks for the feedback; I really enjoyed building it.

The finish is Target EM6000 production lacquer. It is a waterborne topcoat, has ful burn-in. Works much like nitro without the danger and smell. I use it on guitars too.
 

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Hey - that’s my amp build! Thanks for the feedback; I really enjoyed building it.

The finish is Target EM6000 production lacquer. It is a waterborne topcoat, has ful burn-in. Works much like nitro without the danger and smell. I use it on guitars too.
Thanks very much. That lacquer looks great. I can't stop looking at your cabinet. So nice!
 

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Here's a Tramp I built into a custom head cab I made. Pine and Walnut similar to Ayr's. Live edge through the middle so you can see the tubes glowing in a dimmly lit room. I'm trying to sell this one so I can fund another kit this winter (maybe an 18W?). Pictures aren't great.
 

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