Built another amp, 6g3, it’s killer!

[zguitar71]

I built another amp and this one is absolutely fantastic. I have owned and gigged with some great amps over the years and this one is the best. The 6g3 is just perfect. It can be so clean and yet so nasty whenever I need it. Just a little turn of the v knob on the guitar is all that is needed. 
I have run into a little issue with the PT. It is a Classic Tone 18066 and should put out 330 vac with 120 in but it is 350 and the heater is 6.75 and the rectifier is 5.3 so everything is equally elevated. Right now the plates are running at 448 vdc with a GZ34. I’m going to build a bucking transformer and lower everything by 7% which would put it all in the perfect voltages. I considered changing the pt but I don’t want to spend the $$ on that since I can build the BT for $30. I’m a bit disappointed the Classic Tone PT is over wound but since they don’t exist anymore anyway…

[Gitfiddler]

So basically you built a Brownface Deluxe amp head?

[zguitar71]

Just now, Gitfiddler said:

So basically you built a Brownface Deluxe amp head?

Yes

i did a few mods, I added switching on the cathodes of the preamp for hot/cool/middle biasing. I also added switches to go from 100K and 220k plate resistors. In the end the middle biasing sounds best just like Fender designed (go figure). I like the 100/220 switch to get more headroom if I want but I could get rid of the bias switch. I did it just to see what would happen tonally.  
 

I have a bunch of different speakers I can go through from 1,2 or 4x12 and the same with 10s. I’ve only played it through a single Scumback M75 with the band though. At home through 4x12s it’s unreal but too much for most gigs. 

[kbp810]

Awesome build, and dig the mods.

Your voltages aren't too terribly high; plates are a little on the high side, but a good 6V6GT or 6V6S pair should have no problem handling that. I like the thought on the bucking transformer though to reel it all back into spec. Was going to blab on about just swapping the rectifier for a 5U4 or 5R4, but given the price of tubes these days, the BT solution makes even more sense. So really, I'm just typing all this out for the sake of typing it all out, lol. 

 

 

[zguitar71]

I put a 5aR4 in that I had forever first and the voltages were very low on the plates and I looked at the tube and only 1/2 of it was working. At some point between my last gig with it and putting it in this amp is failed. It was old and cheap to begins with. Then I used a 5u4 after I ordered another 5ar4/GZ34. The voltages were only 6 volts less with it than the new ar4 was when it came.  I did the math and the 5u4 was multiplying at 1.28x, rather robust for one of those. While the new one was exactly 1.3 like it should be. I’ve never measured any of my voltages with these tubes I’ve had for years now. I roll Rectifier tubes for more or less sag depending on what I want at the time. This amp is best with the GZ34. I would like to get the heaters down just to not shorten the tube life. I have some EH 6v6GTs in it and I think they will be ok with the voltage, the bias is at 60% so I’m not pushing them too hard. I also used the bias circuit from the Black Face Deluxe which is very nice when I need to bias it, no changing resistors, just turn a knob. The PT has a 50v tap, I think I’ll always use a PT with a tap forever, it makes life easier down the road. 

[helmi]

I had Jim at Lil’ dawg amps build me a 6g3 head with no tremelo and just the bright channel. 2 knobs, thats it. What a little fire breather. the brownface deluxe sound is a great one.

[bolero]

Cool amp!!