New build: 5f2-a "Two Stroke" with 6L6

[theprofessor]

Almost there. Still awaiting the 68k resistor I need. And I've got to do the power wiring. And check everything over, of course. I found that an M6 washer works nicely for installing the 3-way mini SPDT 1/4" boost switch.

 

[theprofessor]

Made a boneheaded mistake at the input that I’ll need to correct…

 

[theprofessor]

Finished wiring everything up. Please let me know if something looks amiss or if I have employed any not-best practices.

 

[Peegoo]

^^^That is nice clean work!

 

[screefer]

Super clean!

 

[theprofessor]

I was able to go through the startup process today, and the amp didn't blow up. I started off with a 360R bias resistor, but after startup I changed to a 300R resistor. I currently have a Phillips-labeled SylvaniaECG 6L6GC in the power section. Speaker is a reconed Oxford 12T6, but it was just sitting on a table. After letting the amp warm up for a while and playing through it, here are the numbers:

Wall voltage was around 124-125 VAC. According to my AmpRX Brown Box, it was running at about 122 VAC under load. With that 300R cathode resistor and the SylvaniaECG 6L6GC:

6L6GC plate: 389 VDC
6L6GC cathode: 23.8 VDC
B+1 397 VDC
B+2 345 VDC
B+3 229 VDC

At plate-to-cathode voltage of 363 VDC, the 6L6GC was drawing 76 mA of current. That's just below "average," dissipating about 27.5W (92%). I've also got a pair of vintage Tung-Sol 5881's that I don't really want to break up but that I'd like to hear. I suppose I'd need to go back up to a 360R cathode resistor or thereabouts to make that work. I don't much like the idea of such a compromise on bias between a 6L6GC and a 5881. At some point, I'll just need to decide which one I want and use it.

I also found the amp to be a bit too bright. But I may be hearing gain. I was using a humbucker-equipped Les Paul, and I had a new JJ 12AX7 in V1. I think I'll leave things alone until I get the Oxford 12T6 into a cabinet. Then I can audition it with a 5751 or a 12ay7 as well, which I think I wanted to do anyway. And with standard Tele single-coils or P-90's, which I play most of the time.

 

[theprofessor]

 

[theprofessor]

Made some good progress on the cabinet.

 

[theprofessor]

Just about done. Nearly all that's left to do is finish the cabinet. Since yet more rain is in the forecast, I'm going to put it all together and play it and wait on the finishing. In fact, I've done that already, and this amp is SUPERB. Really versatile with just that three-way switch. And it's darn loud, too! The Oxford 12T6 does a great job with this circuit. And I am LOVING the look of this thing!

 

[screefer]

Kudos!!!

 

[68tele]

sound clips...?

 

[theprofessor]

sound clips...?

I'll try to get to some of those in the next week or so. When I do, I'll post them here.

 

[FenderLover]

Wouldn't a true 2-stroke have 2 of something? A pair of 8's? a pair of 10's?
Nice work!

 

[theprofessor]

Wouldn't a true 2-stroke have 2 of something? A pair of 8's? a pair of 10's?
Nice work!

Thanks! Yes, the original Hunter "Two Stroke" was a parallel single-ended amp with two output tubes. The later revision I made has one output tube. So I'm going to call mine the "Single Engine" or something like that.

 

[symbiotic]

In motorcycle terms, a large single-cylinder engine is a "thumper"... just sayin...

 

[theprofessor]

I like that! I’m not a rider, but I may use it!

 

[SnidelyWhiplash]

OP, any particular reason you used Jupiter for your signal caps, or did you consider others???

Just curious...

 

[King Fan]

What's in a name? Everything, maybe.

A 'Singleton' is, basically, "not a twin."

It's apparently also a Scotch, which brings up 'Straight Shot.'

From there, it's just a pitch on down the links to 'Wee Dram.'

Ah, whiskey. 'Single Barrel,' please.

From whiskey to buffalo rifles? 'Single Shot.'

Back at bikes, Ducati's single-cylinder superbike? 'Supermono'.

 

[theprofessor]

OP, any particular reason you used Jupiter for your signal caps, or did you consider others???

Just curious...

I have used Mallory 150's a lot in the past. They are bright and clear and cheap. I like all three of those things. Jupiters are quite expensive, but I thought I'd give them a try again, especially because this is a tweed-style. I tend to think of Jupiter yellows in tweeds and Mallory 150's in blackface-style amps, though of course that is not a hard and fast thing.

 

[theprofessor]

What's in a name? Everything, maybe.

A 'Singleton' is, basically, "not a twin."

It's apparently also a Scotch, which brings up 'Straight Shot.'

From there, it's just a pitch on down the links to 'Wee Dram.'

Ah, whiskey. 'Single Barrel,' please.

From whiskey to buffalo rifles? 'Single Shot.'

Back at bikes, Ducati's single-cylinder superbike? 'Supermono'.

I love these! So many good ones. I have a side hustle that is train-themed. Any train-themed ideas? But single barrel could really win the day, even if I don't come up with a train-themed name. Both whiskey and a shotgun.