.

Concerning DC heating: I was not so much concerned about the coupling inside the tube. Just having wires carrying AC current close the high impedance inputs seems dangerous to me.
With respect to the grounding scheme, I think there are two options: Either you make sure that the impedance of the ground path is extremely low or all connections to ground meet at a single point without any branches (, which may require you to use insulated jacks etc.).

Wilko

Gentlemen,
I promised myself when I joined the forum I would stay out of these kind of conversations,
BUT as I have already stuck my nose in this; in for a penny, in for a pound, eh?

First of all I am NOT Andy Marshall, Paul Rivera, Randall Smith or, lets not forget, Hartley Peavey. However, I know my way around the inside of valve amps; a little. (add dot com to my username to check my bonafides). Seeing Mike's mention of "The Valve Wizard" I had to check it out; very interesting.
Here are a couple of quick quotes:

"If the heater supply is not elevated but simply grounded, then this ground connection
can usually be made to any point on the chassis, or else to a point close to the
reservoir capacitor. However, heater hum is induced in many ways, so it may be
worth experimenting by making the connection to various points on the circuit
ground to see if any particular place happens to give the most favourable hum
performance."

Notice he said "elevated".

"Of the various sources of noise in an amplifier, bad grounding is probably third on the list (after heater hum and resistor hiss)."

I would rank them: power supply, bad grounding, resistor hiss, and heater hum; but then I "elevate" my heater supply.

Andy, and Paul too I think, use DC heaters. Obviously if Andy does it there is a reason. I just don't see the need for all the added complexity/expense.

IF you wind your supply tightly, keep it tight to the chassis (a la Harry Joyce), the 6v radiation (they are out of phase so isn't it 3.15v?) is kept to a minimum. IF on the other hand, you elevate the wires (a la Fender), voltage is radiating all over the circuit.

BUT, to quote Mike:
"After reading that and other gfrounding (sic) articles I am almost convinced that none of my Fender amps can even work without excessive noise... and yet they do just fine."

And there you go; they work! In fact, they are the standard by which all are measured.

I got involved because I was concerned that tying the Cathode of the output valve to the heater string would INCREASE noise. Evidently, "balancing" the heater string is NOT that important (although ALL production amps are either c-tapped or have the 2-100 ohm resistors). Not as important as "elevating" the string anyway. Again, it worked!

Now understand, I'm NOT telling you, you can't or shouldn't DC the heater string. I'm saying, in my experience, it isn't necessary.

This IS intended to be a discussion, NOT a lecture.

Careful layout and attention to detail will, IMHO, work every time!

Mike has done that, and will report back HIS experience, and we will all learn from that.

Its been fun but, I have a studio to build, and will  now bid you all adieu...

Tom

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Mike,

Enjoy!!!

Wilko

You know, single ended is what class A amps really are all about. An AC-30 "sounds" like an AC-30 for a lot of reasons, the cathode biased output section, for me, being last on the list; its still a push-pull amp. (I know I'm in for it now, how dare you)
It is tough getting the "big" clean sound.
What speaker are you running? I would go with an alnico 10".
I'm a big fan of the Emminence Legends, and I prefer the kapton voice coil over the paper.

Enjoy!

Tom

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.

I have been following this thread...and I'm a bit jealous to be honest!

I have some other priorities to throw money at right now, but would love to monkey arond with one of these.

Really great job.

gotta agree with skull....

.

Mike,

Which The Stumble?

Freddy, Peter or my favorite (Freddy is "The Guy" to me but...) Dave Edmunds from Blues Helping?

Dave just nails it (ES335 >Black Bassman>4x12 Marshall, BTW)

+1 on getting the 57 up close and personal!

Keep Rockin'

Yeh, I liked the tone. There's always a huge disconnect in these types of discussions because everyone likes different music. Some people want huge chugging low end guitars and others want lighter stuff that floats above a solid bass. I'm more often the latter type. I like that Fender Champ through an 8" speaker sound myself. I wish I had one, since it would save me from rolling off so much low end. An amp like that, with a little off axis to cut a bit of the crunchier stuff, probably could easily have a nice, balanced tone that would work well for a lot of the kind of things I'd want to do.

Skull,
I'm thinking there is a beautiful palate of sounds in that amp.
Mike's on a journey to find them...

I'd put an EL-34 in there once in a while, with a Paul in front of it!

Tom

That sounds good to me. I like that kind of tone. As I said above, if you are going for a full bass sound, the guitars can be quite toppy as long as they are balanced volume-wise against the low end. That can allow the guitars to peek out just where they need to in the frequency range without taking up other space. You wouldn't want every single guitar part to sound like that necessarily, but that's a very useful tone for a lot of things.

I guess it's somewhat part of those champ-like designs that they can get a little farty when pressed into natural overdrive beyond the warm breakup point? It seems to be from what I've heard. But you can EQ that out in large part and it's often in a range where you'd want to do that anyway to leave it for other stuff.