I Can't Stop! Check My Attempt?

[LedZepp007]

Hi, In addition to my musings about different tweed circuits that I might want to build, I've been generally lusting for a 6G3. However, I'd like to keep it as simple as possible (for tone's sake).

I modified a schematic to (hopefully) be one channel, no tremolo, with cathode biasing for the power tubes (as opposed to the standard fixed). It's attached. If it's stupid, just tell me.

I thought this would be a good exercise toward starting to better understand schematics.

Thanks!

[sluckey]

I'd put a 250Ω/10W and 50µF cap on the cathodes of the 6V6s.

[Colossal]

Good job, that'll be a ripping amp. Get to work!

[LedZepp007]

I'd put a 250Ω/10W and 50µF cap on the cathodes of the 6V6s.

Like this?

Thanks for the help everyone!

[Colossal]

Yes, like that, but it would be good to up the cap's voltage handling to 50V or better for the power tube cathode bypass. 16-25V bypass caps will do in the preamp.

[Stevem]

I would get a 50uf and a 100 uf and audition both at all volume levels and then pick one!
Also if the amp will get cranked above 7 at times then I would up those first two power supply nodes to 30 or 50 uf values, a Marshall duel can type makes that easy, but grounding wise be sure to land all the other filter ground and preamp grounds at the input Jack !

[10thTx]

I'd use a 33k instead of 68k input resistor

[LedZepp007]

Thanks for the help everyone.

Does anyone know of any software that's good for making layouts?

[10thTx]

I probably have drawn up between 100-150 layouts using ExpressSCH. Which is a free download.

There are many examples here:

http://el34world.com/Forum/index.php?board=12.0

And an example below attached. You can come back and color code things using PAINT on windows.

With respect, 10thtx

[johnnyreece]

I like DIYLC. It's free, and, while it has limitations, it does make relatively good looking layouts.

[LedZepp007]

Thanks everyone. I may try to put together a layout in the next couple of days.

My thoughts are building in an 18-watt Marshall chassis and 2x12 cabinet (enlarging the power tube and rectifier holes). What would some good transformer choices for a 6G3 build be? I could always just use the MM clones, but maybe something else would sound better?

Should I add a choke to the design rather than upping the filter caps as was suggested earlier?

Thanks!

[LedZepp007]

I guess I should ask--worth it to get MM transformers or should I look at something cheaper?

[Colossal]

I guess I should ask--worth it to get MM transformers or should I look at something cheaper?

That is like asking Apple or PC. Guaranteed to start a war and ALL of it is based on opinion. Picking a transformer, a tube, or a capacitor should be based on understanding the application requirements with some filtration through your personal values. Some people do not hear or care about any difference in materials and are highly price sensitive so they'll pick what's on sale or a deal on eBay. Others might accept the possibility of early failure or marginal materials and poor part to part precision as a perfectly reasonable exchange for a low price. Others view vintage correctness as a necessity and are willing to bear a higher cost for a niche product.

If your build must be a spot-on vintage clone, then select a good quality vintage replica transformer set. Mercury, Heyboer, or ClassicTone are good choices in general for vintage correct amps. If you are just building a project amp or vintage variant and just need an output transformer with a certain primary impedance with a bit lower price, Edcor and Hammond have a big catalog with many options and are good quality choices.

The important thing is to understand what is required for your amplifier such as picking an output transformer with the correct primary and secondary impedance etc.

[LedZepp007]

What about this modified schematic of a diode rectified, cathode biased 6G2?

Thanks!!!!

[robrob]

Zep, I prefer the 6G3's long tail pair phase inverter for its own overdrive tone and the much larger voltage swing to push the power tubes to full overdrive. You can always use a solid state inverter in the 6G3.

Since you're using one input the 6G3's first grid stopper should be 33k (like the Princeton, not 68k.