The difference in designing a tube circuit vs. a solid state circuit is akin to the difference in speaking French and English. Neither is hard...as long as you grew up in it. That's not to say that you can't learn a new language and become fluent in it.
I know that in my case I came from tubes to solid state and that I still, after five or ten years, have to consciously force myself to think in terms of current instead of voltage for bias. It just ain't natural. JEFTs and MOSFETs "feel" more normal to me than bipolars in this respect, although I confess to being uncomfortable with enhancement mode devices where you have to push the control element (i.e. Gate) ahead of the Source. I keep feeling like I'm going to draw grid current or something, not to mention burn the device.
That said, I've reverted to tubes twice recently: the latest iteration of my crossover, and a tube amp that I've agreed to build for a buddy (assuming that the old Peerless transformers he's providing are still good--fingers are crossed). It's like coming home.
He's also knowingly playing guinea pig for a few ideas that I've had since I built my no-holds-barred tube amps. If things pan out, I'll rebuild mine in like manner. Might even "X" the critters, just for fun.
I have no doubt that Nelson could build a tube circuit if suited his needs. After all, it isn't that difficult...you just have to think voltage instead of current.
Grey
I know that in my case I came from tubes to solid state and that I still, after five or ten years, have to consciously force myself to think in terms of current instead of voltage for bias. It just ain't natural. JEFTs and MOSFETs "feel" more normal to me than bipolars in this respect, although I confess to being uncomfortable with enhancement mode devices where you have to push the control element (i.e. Gate) ahead of the Source. I keep feeling like I'm going to draw grid current or something, not to mention burn the device.
That said, I've reverted to tubes twice recently: the latest iteration of my crossover, and a tube amp that I've agreed to build for a buddy (assuming that the old Peerless transformers he's providing are still good--fingers are crossed). It's like coming home.
He's also knowingly playing guinea pig for a few ideas that I've had since I built my no-holds-barred tube amps. If things pan out, I'll rebuild mine in like manner. Might even "X" the critters, just for fun.
I have no doubt that Nelson could build a tube circuit if suited his needs. After all, it isn't that difficult...you just have to think voltage instead of current.
Grey
GRollins said:
Let's not discuss Canadians, please. Nor Cajuns !
If your reasoning holds truth, Grey, a number of audio names have been bad boys.
Just one : Mark Levinson.
I can mention at least 10 more who switched from silicon to vacuum.
I am a person who enjoys reading a book in any language, writing one is definitely not my aim.
The room was dark. Against the forward wall were hulking rectangular shapes, dimly seen. Smaller shapes were gathered at their feet.
One, somewhat smaller than the rest, began to glow--points of light could be seen within its skeletal frame.
It had heard its master's call...it was time to awaken...
The ghosts of sounds long dead were clamoring to be heard...
Grey
One, somewhat smaller than the rest, began to glow--points of light could be seen within its skeletal frame.
It had heard its master's call...it was time to awaken...
The ghosts of sounds long dead were clamoring to be heard...
Grey
Well, Grey, here's your killer opportunity to design a tube
X front end for the Monster (whoops! now I'm gonna get
sued by Monster Cable!)
A nice diff pair, current sourced and cascoded, with current
sourced Cathode followers to drive that big fat output stage.
We will need an output that will drive maybe +-80V at 25 mA
peak per side. No feedback from output required. No direct
coupling required.
X front end for the Monster (whoops! now I'm gonna get
sued by Monster Cable!)
A nice diff pair, current sourced and cascoded, with current
sourced Cathode followers to drive that big fat output stage.
We will need an output that will drive maybe +-80V at 25 mA
peak per side. No feedback from output required. No direct
coupling required.
A challenge, eh?
+-80V...no problemo.
25mA...lemme think about that one.
Direct coupling from differential to follower is pretty much a given (at least in my book), but I will want to use caps at the outs to protect the output stage. Might not be a bad idea to stagger the turn-on...tubes first, followed by outputs twenty to thirty seconds later.
(Mutter, mutter...the sound of me scratching my head...eyes squinted at ceiling...scribble, scribble...)
Okay, let's use a solid state CCS, as a tube one would require a moderately deep negative rail, and that's going to really, really intimidate some folks.
One the other hand, it might be fun to use a tube current source for the follower to act against...
(Mumble, mumble...sound of phone dialing, me telling wife to leave out the Assam tea [gonna need some serious caffeine]...)
All righty, I'll see what I can do about this.
Grey
+-80V...no problemo.
25mA...lemme think about that one.
Direct coupling from differential to follower is pretty much a given (at least in my book), but I will want to use caps at the outs to protect the output stage. Might not be a bad idea to stagger the turn-on...tubes first, followed by outputs twenty to thirty seconds later.
(Mutter, mutter...the sound of me scratching my head...eyes squinted at ceiling...scribble, scribble...)
Okay, let's use a solid state CCS, as a tube one would require a moderately deep negative rail, and that's going to really, really intimidate some folks.
One the other hand, it might be fun to use a tube current source for the follower to act against...
(Mumble, mumble...sound of phone dialing, me telling wife to leave out the Assam tea [gonna need some serious caffeine]...)
All righty, I'll see what I can do about this.
Grey
My goodness this is getting interesting! 
FWIW, the power supply rails will be typically around ±95VDC since the transformers we’re using are 120VAC to 70VAC.
Since were leaving the space at the very top of the upper chassis for the front-end, we can accommodate whatever y’all dream up.
Hey Zero Cool: Shall we post a sketch of the proposed chassis design?
Hey Mr. Pass: Shall we post the schematic for the output stage? BTW, I received shipment of 3000 MOSFET’s today.
-Casey Walsh
FWIW, the power supply rails will be typically around ±95VDC since the transformers we’re using are 120VAC to 70VAC.
Since were leaving the space at the very top of the upper chassis for the front-end, we can accommodate whatever y’all dream up.
Hey Zero Cool: Shall we post a sketch of the proposed chassis design?
Hey Mr. Pass: Shall we post the schematic for the output stage? BTW, I received shipment of 3000 MOSFET’s today.
-Casey Walsh
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