Identify circuit

[tedmich]

My guitar teacher was in fact, Danny Gatton.
Also, one lesson from Albert King...
Also pointers from Howard Roberts.

Who taught you how to play guitar? Oh that's right, you don't play guitar.

Nobody said I was fast fingers...I broke my wrist a while back. I was a lot better when I was a kid.

I never liked Clapton that much. I was always thinking that he rode on the wings of Jack Bruce.
I could say that I liked Jack Bruce and Ginger Baker more, as musicians, and Jack Bruce is more fun a person, I think.
When I first met Jack, I said it was a great honor to meet him.
But then he said it was more of an honor to meet me...
then we argued about who's honor was greater, his or mine...and at the time hilarious.

Even at 68 years old, he was jumping around on stage like a mad man, he was singing and playing those old Cream songs better than ever.
Then he signed my friend's strat with a soldering iron, that he keeps for autographs, in his guitar case.

But Danny Gatton had a shop over in Maryland, in an old bank building, and people told me to go take lessons from him.
At the time, $35 was a lot for a 1/2 hour guitar lesson, but for some reason, I did...and I had to drive more than 50 miles to get there.
But I considered that worthwhile if I was going to learn something. I had no idea who Danny was, people called him "the greatest unknown guitar player."

And the old bank building had a huge bank vault, and Danny kept his guitars in the vault.
But he had no idea what the combination was, and never locked it. Pretty funny.
But the vault door was closed, and looked menacing, so nobody would dare touch it.

[gui_tarzan]

The "blue goo" is probably Permatex gasket sealer. Good stuff in an engine. Must be a good insulator or it would have gone up in a flash by now.

I guess there must be some secret innovation under that P'tex, and probably a prototype since it's mounted on tongue & groove laminate flooring.

[big_teee]

How did you find the time? You must have been incredibly busy designing and building the space station, when you weren't putting together 22KW PA systems, when you weren't scuba diving all over the world, when you weren't designing, modifying and building incredible amps for all the greats, when you weren't putting silver wiring looms in the ships you probably built on your lunch break, all while you were actually repairing more amps than any of us have ever seen. Did I miss anything? Plenty I'm sure.

The Dos Equis "most interesting man in the world" sure doesn't have anything on you, does he.

I agree, please go back to the No-Mercy Method!

[R.G.]

Where is Carly Simon now that we need her?

"You're a legend in your own mind, a hero ... but not quite..."

"You're so vain, you probably think this song is about you."

Just the theme songs for a man out standing in his own fields.

[Leo_Gnardo]

Danny Gatton, people called him "the greatest unknown guitar player."

All the guys in my neighborhood sure knew who he was, then look what happened. Actually, don't look, too gruesome. Poor Danny, and poor us, all we have is recordings now.

But Jimmy Page bought me a beer! True fact.

And when Mick Jagger had his own band for a while @ 1988-9, the backup singers bought me lunch. Good folks! Terrific singers.

[NateS]

I guess there must be some secret innovation under that P'tex, and probably a prototype since it's mounted on tongue & groove laminate flooring.

That's not laminate flooring. It's a secret special sauce layering of tonewoods, each contributing its own magic to the mystery tone.

[Tom Phillips]

...a secret special sauce layering of tonewoods...

Otherwise known as Formica.
Formica (plastic) - Wikipedia, the free encyclopedia

[J M Fahey]

Formica is quite good as eyelet board materials go.
Definitely better than damp Fender black fiberboard.

As of SGMīs latest delusions:

"I LOOK AROUND AND SEE I AM THE CENTER OF THE UNIVERSE":

[Gingertube]

Shocki etc.
Way up this thread you talked about maybe implementing a fixed/cathode bias switch to see what you preferred.

My experience:
I built a London Power Standard, in that I used a quad of 6V6 for the output, each output tube pair could be switched between cathode and fixed bias. I found that with the (common to the push pull pair) cathode bias resistor bypassed with a capacitor there was basically no difference in sound between fixed and cathode bias, with no bypass capacitor there was a difference. This is the way that Kevin O'Connor recommended it was built too (without the cathode bypass cap) and in subsequent email discussion with him he confirmed that he left off the bypass cap in order to get a difference in sound between cathode and fixed bias switch settings. He had also concluded that with a bypass cap there was little if any sonic difference between fixed and cathode bias.

These days I generally used a combination of the two (fixed and cathode bias) - I use a common to the output tube pair cathode bias resistor of approximately 25% of the normal value (no bypass cap) and then apply fixed bias to the grids to set the required idle current. The common, partial, cathode bias resistor applies some common mode local feedback and imparts some odd harmonic suppression via "harmonic equalizer" action but is particularly effective in suppressing intermodulation products with residual power supply ripple. This is something I learned from the Tube HiFi design I do. The effect is subtle but it eliminates some "muddiness" in the bottom end.

So you may want to give that a try.

Cheers,
Ian

[Dave H]

...These days I generally used a combination of the two (fixed and cathode bias) - I use a common to the output tube pair cathode bias resistor of approximately 25% of the normal value (no bypass cap) and then apply fixed bias to the grids to set the required idle current.

A simple way to try that in a cathode biased amp would be to reduce the cathode resistor to 25% and just add a zener in series with it for the fixed bias voltage.

[Mick Bailey]

I wonder if that amp has the proper cutouts to prevent the mains switch from rotating? Looks like if the nut came loose it could rotate and touch the chassis if not. There's a backup safety tie-wrap to rely on anyhow. For a newish amp not to have protection over exposed mains terminals (including the IEC inlet) isn't good practice.

Anyhow, looks like a straightforward design and about the same amount of work as a 5E3.

[shocki]

Can anbody see what kind MV his is using in this amp? Or how the gain is controlled? The pot close to the input is the gain Knob. The next knob is the vol knob.
Thanks

[J M Fahey]

Itīs very simple, definitely not PPIMV and, personal opinion, wonīt offer too much grit, to say it politely.

No time to lift the entire schematic but from what I see, looks like a triode gain stage > volume ("Gain") > second triode stage > Fenderish tone controls > classic Fender volume control after it (here called Master) > standard PI > Power tubes.

Thereīs just one double triode available for the preamp so it canīt have much more than described.

Nothing new, shows some typical traits of many small, relatively unexperienced builders, (I wouldnīt call them "boutique" by any means):

1) canīt really design, so most they can do is to make a collage of blocks "borrowed" from other amps.

As in Mc D "new" hamburgers they offer every month: how many combinations can you turn out with so little "parts" available?
Ok , one month you skip the cheese and add *two* slices of bacon, next month you pull one and add extra lettuce .... in less than a year you are repeating yourself.
Same here.

2) to compensate for the lack of originality, they build the same old tired circuits (mind you, they may still sound very good ... ) but with "superior / expensive parts" ... so youīll find plenty of SoZo/Solen/whatever caps, Mercury Magnetics iron, NOS tubes, etc.
Plus killer Tweed, often very original (sometimes ridiculous) cabinet designs, etc. , sometimes beautiful polished wood cabinets, etc.
But inside ......

3) often beautiful internal wiring, of course turret construction , maybe silver wire, etc. ,,, coupled to gross mistakes such as that hot cathode bias resistor cooking *two* caps at the same time (now thatīs efficiency).

Or not fatal but minor mistakes such as non twisted filament wires (in fact run wide spaced one on each side of tube sockets to guarantee some vintage hum), gain and tone control grounding points straight to different pot cases instead of, say, a dedicated ground buswire with independent grounding, etc.

Go ahead, build your own, it will be at least as good, and probably better.

[jazbo8]

Why are we spending time on this un-remarkable build - perhaps to learn what NOT to do... that's the lesson for today.

While we are on the subject of building, check out this "professional" build by Two Rock - truly a sight to behold...

[gui_tarzan]

Please tell me that's not a production amp...