Identify circuit

[shocki]

OK. Now I understand that you guys were talking about drawing the schematic from the photo. If you are going to build your own amp you can start with a know circuit of the amp you like best. Then tweak to taste including the cathode vs. fixed bias. Lot's of fun. There is probably nothing all that special about the circuit in the Morgan amp circuit that you referenced in the first post. It does look like a nice compact single channel amp concept. You can adapt many of the classic Fender BF circuits using the same approach.

I have an amp with switchable Cathode/Fixed Bias (forgot about that switch). Just tried it. The difference is very subtle and not night and day at all. I like the fixed bias a little bit better. It is little bit more "polite" and tighter. But the difference is really small. I will start with a basic BF Bassman build.

[soundguruman]

I don't like polite amps. I like rude obnoxious amps.
I like it when the amp is almost, but not quite, out of control.

If the neighbors are pounding on the wall, it's working right.

[R.G.]

I don't like polite amps. I like rude obnoxious amps.
I like it when the amp is almost, but not quite, out of control.
If the neighbors are pounding on the wall, it's working right.

What a surprise.

I'd have expected nothing less.

[g1]

Sort of like the "dog resembles it's master" thing I guess.

[Justin Thomas]

I like this because I understand the hyperbole. I too like very raw unrefined tone... part of why I play a Tele, too - uneven, raggedy, barely controllable, you have to fight it and don't know what's coming next...

Not that I advocate getting the cops called, because then, NOBODY has any fun.

I think the Morgan is something I would like VERY much. I like the sounds of small Ampegs, ~20W cathode biased... I'd call it an "intermediate" Fender type thing... it's not that hard to change from cathode biased to fixed, though, maybe $5 in extra parts? Build it & see, you might be pleasantly surprised, abd there's enough "typical Fender" already out there.

Justin

[gui_tarzan]

$1799???

[J M Fahey]

$50000 ?

[Tom Phillips]

$50000 ?

It's interesting that the $50,000 for that one is the used market price. The original sell price direct from the maker was in the $2k-$3k range.

[soundguruman]

I like this because I understand the hyperbole. I too like very raw unrefined tone... part of why I play a Tele, too - uneven, raggedy, barely controllable, you have to fight it and don't know what's coming next...

Not that I advocate getting the cops called, because then, NOBODY has any fun.

I think the Morgan is something I would like VERY much. I like the sounds of small Ampegs, ~20W cathode biased... I'd call it an "intermediate" Fender type thing... it's not that hard to change from cathode biased to fixed, though, maybe $5 in extra parts? Build it & see, you might be pleasantly surprised, abd there's enough "typical Fender" already out there.

Justin

I know exactly what's coming next, because I know how to play electric guitar, taught by Danny Gatton.
And don't you forget it.


Oh now, that's a lovely layout.
Is that Play-Doh insulation? Only the finest hand selected...

[Leo_Gnardo]

I have an amp with switchable Cathode/Fixed Bias (forgot about that switch). Just tried it. The difference is very subtle and not night and day at all.

I did the experiment @ 20 years ago. By ear, your conclusion matches mine. By 'scope, as expected more clean power available with fixed bias but it IS our ears we're trying to please, right? After that I told customers who wanted to change self-bias to fixed-bias, or put in a switch, don't bother.

Bias adjustment is accomplished by changing the cathode resistor. You *could* fit the amp with a "honking big pot/rheostat". Bias voltage is the voltage developed across that cathode resistor. You subtract that from the plate voltage, multiply the result by bias current and there's your plate dissipation figure.

- - - - - - - -

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.

[J M Fahey]

I know how to play electric guitar, taught by Danny Gatton.
And don't you forget it.

Answer 1: Yea, also Jimi Hendrix washed your car, Eric Clapton walked your dog and you got to sleep with Michael Jackson

Aaaaajuuuummmmm ........ boring ....... next?

Answer 2: ok fastfingers, post some of your lightning chops.
**Danny Gatton** ???????????????????

[soundguruman]

Answer 1: Yea, also Jimi Hendrix washed your car, Eric Clapton walked your dog and you got to sleep with Michael Jackson

Aaaaajuuuummmmm ........ boring ....... next?

Answer 2: ok fastfingers, post some of your lightning chops.
**Danny Gatton** ???????????????????

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, at the Penny Lane thing in Honolulu, 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.

Hendrix? my hero of course. If I had the acquaintance, would not have asked him to wash my car.
But I would have certainly asked him for guitar lessons, given the opportunity.

The closest I came to seeing Hendrix, was to almost buy tickets to one of his concerts.
I ended up going to Astro-World, instead.

[g1]

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.

[gui_tarzan]

That's pretty impressive, SGM. The closest I ever got to famous people was opening for Little Jimmy Dickens back in the early 80s and for Caedman's Call six years ago. Oh, I have Dick Sargent's autograph too, as well as Bill Freehan and a few of the Detroit Redwings from the early 90s. I was in an elevator with Sergei Federov and Vladimir Konstantinov once. My son had water spit on him by Nikki Sixx while running a camera at the local casino last summer. And yelled at by a guy from another famous band, I forget who they were though.

[gui_tarzan]

Nobody said I was fast fingers...I broke my wrist a while back.

Oh the temptation is way too strong... must not comment...