Vince,
I'd estimate a final rail in the vicinity of 18 or 19 volts. This is actually close to where I was running my Mini-A at full power (I was holding it down to 15V rails with a Variac).
The transformer will be warm to the touch, but not too bad. What you'll need to watch is your device dissipation, which will be on the order of 38W/device. Make sure you've got plenty of heatsinking if you're going to run them that hot.
Grey
I'd estimate a final rail in the vicinity of 18 or 19 volts. This is actually close to where I was running my Mini-A at full power (I was holding it down to 15V rails with a Variac).
The transformer will be warm to the touch, but not too bad. What you'll need to watch is your device dissipation, which will be on the order of 38W/device. Make sure you've got plenty of heatsinking if you're going to run them that hot.
Grey
Re: Compensation Cap
Aha. Without C3 as I see you turned the dynamic current source to ordinary one - to the SE. Does it really change the sound to more detailed?
Aha. Without C3 as I see you turned the dynamic current source to ordinary one - to the SE. Does it really change the sound to more detailed?
One more question before I order!!!
Grey, one more question. I reread all your posts here and I was just wondering exactly what you meant. By increasing R11 to 220k ohms, do I still need to increase R18 and 19 to .33 ohms?
It won't hurt to buy all them right now, but when I go to put this thing together, I want to use the correct values for R11, R18 and R19.
Thanks for putting this together. Let you know how it turns out.\
Sorry to be so think headed about this!
Vince
Grey, one more question. I reread all your posts here and I was just wondering exactly what you meant. By increasing R11 to 220k ohms, do I still need to increase R18 and 19 to .33 ohms?
It won't hurt to buy all them right now, but when I go to put this thing together, I want to use the correct values for R11, R18 and R19.
Thanks for putting this together. Let you know how it turns out.\
Sorry to be so think headed about this!
Vince
can the mini A live from +-6V i just found some nice 150-200A batteries (im not shure what they are called in english lead based but you dont need to add any water to them) they way like a ton each..but i only got to possibly 3pcs
/micke
/micke
PCB Layout?
Grey Yoo Da Mann! really nice circuit, a lot of these babies will be built, any chance of the pcb layout being made available for us idle/incapable/software-less types.
Mozfet.
goodstuff57@hotmail.com
Grey Yoo Da Mann! really nice circuit, a lot of these babies will be built, any chance of the pcb layout being made available for us idle/incapable/software-less types.
Mozfet.
goodstuff57@hotmail.com
balanced inputs?
Hi Grey,
I have a tri-amp sound system that's balanced. This mini-fellow would come in handy on my hf horns. How would you go about creating a balanced input on this little marvel?
A drawing's worth a thousand words.
John Inlow
Hi Grey,
I have a tri-amp sound system that's balanced. This mini-fellow would come in handy on my hf horns. How would you go about creating a balanced input on this little marvel?
A drawing's worth a thousand words.
John Inlow
Re: Hot dog!
Grey,
It's like you were reading my mind... i've been re-reading nelson's AE Zen article, and was wondering about a smaller version -- 5-10W. The spare 225VA 18-0-18 toroid with a choke input looks like a good candidate for PS :^)
Thanx.
dave
Grey,
It's like you were reading my mind... i've been re-reading nelson's AE Zen article, and was wondering about a smaller version -- 5-10W. The spare 225VA 18-0-18 toroid with a choke input looks like a good candidate for PS :^)
Thanx.
dave
thanks
vdi_nenna,
Thanks for the tip. Got by me, somehow. What do you want to bet that this is where Nelson Pass is planning on taking us eventually? Hope we're not stealing his thunder......
John Inlow
vdi_nenna,
Thanks for the tip. Got by me, somehow. What do you want to bet that this is where Nelson Pass is planning on taking us eventually? Hope we're not stealing his thunder......
John Inlow
Contrary to what some have supposed, I don't know Nelson personally. We live on opposite sides of the continent. This is a clever ploy on his part to keep me from showing up at the Pass Labs plant with my offbeat ideas and a hastily scratched out schematic.
The fiend.
The scoundrel.
However, his days are far more productive without me getting underfoot, I'm sure. I had no idea that the Zen would be getting the Aleph treatment when I began the Mini-A. It's just something that my curiosity drove me to do.
(Hey, fellas...want a Mini-X?)
Moral of the story: Don't ever stir Grey's curiosity. Bad idea. <i>Very</i> bad idea.
My intent is/was not to steal Nelson's thunder. I just like playing with this stuff.
Okay...on to the questions, with apologies to anyone I miss and to everyone (yes, Vince, I mean you) who's been waiting.
Vince--When it comes to setting the bias, think of R18 & 19 as the coarse adjustment, and R11 as the fine-tuner. I'm short of parts (read: money) and have to do what I can with what I have on hand. I've got a few .47 ohm 2W resistors, and a goodly selection of 1/2W values, but I don't have .33 ohms on hand. So I made-do. In your case, use the .33 ohm (or .36 or .39 or...) resistors and fiddle R11 until the bias is where you want it.
hifi--I think you'll find that +-6V rails are a bit light. The 9V Zener in the front end won't come up, for instance. That's not to say that you couldn't reconfigure the current source, though...
mozfet--No PCB at present. I may get around to doing one at some point in the future, but at the moment, I'm hip-deep in alligators and don't have time. Gawd, I wish I had someone I could palm some of this stuff off on. "Minion, today I want you to work up a PCB for the Mini-A." In the meantime, I'll just keep dreaming of a day when I can get to my ideas while they're hot.
carpenter--Grafting a balanced front end onto the Mini-A shouldn't be all that difficult. Yes, as Vince pointed out, I believe someone has already done it, at least on paper.
Koy--Q5 is the protection circuit. It senses the current going through R19 via R17 & R13 (they form a voltage divider that sets the trigger point). Should the amp experience a short, the current through R19 increases, which increases the voltage drop seen at the base of Q5, which switches on and limits drive to Q7. Or at least that's the way I read it. I haven't tested the poor thing with a screwdriver--just don't have the heart (or the time).
So many ideas...so little time.
Did I mention the Difference Engine?
Hagrid: "I shouldn't have said that!"
Or how about the...
I'd better stop while I'm ahead. I can't even keep up with what I've got on the burner now. (<i>Grumble, grumble...mutter, mutter...</i>)
Grey
The fiend.
The scoundrel.
However, his days are far more productive without me getting underfoot, I'm sure. I had no idea that the Zen would be getting the Aleph treatment when I began the Mini-A. It's just something that my curiosity drove me to do.
(Hey, fellas...want a Mini-X?)
Moral of the story: Don't ever stir Grey's curiosity. Bad idea. <i>Very</i> bad idea.
My intent is/was not to steal Nelson's thunder. I just like playing with this stuff.
Okay...on to the questions, with apologies to anyone I miss and to everyone (yes, Vince, I mean you) who's been waiting.
Vince--When it comes to setting the bias, think of R18 & 19 as the coarse adjustment, and R11 as the fine-tuner. I'm short of parts (read: money) and have to do what I can with what I have on hand. I've got a few .47 ohm 2W resistors, and a goodly selection of 1/2W values, but I don't have .33 ohms on hand. So I made-do. In your case, use the .33 ohm (or .36 or .39 or...) resistors and fiddle R11 until the bias is where you want it.
hifi--I think you'll find that +-6V rails are a bit light. The 9V Zener in the front end won't come up, for instance. That's not to say that you couldn't reconfigure the current source, though...
mozfet--No PCB at present. I may get around to doing one at some point in the future, but at the moment, I'm hip-deep in alligators and don't have time. Gawd, I wish I had someone I could palm some of this stuff off on. "Minion, today I want you to work up a PCB for the Mini-A." In the meantime, I'll just keep dreaming of a day when I can get to my ideas while they're hot.
carpenter--Grafting a balanced front end onto the Mini-A shouldn't be all that difficult. Yes, as Vince pointed out, I believe someone has already done it, at least on paper.
Koy--Q5 is the protection circuit. It senses the current going through R19 via R17 & R13 (they form a voltage divider that sets the trigger point). Should the amp experience a short, the current through R19 increases, which increases the voltage drop seen at the base of Q5, which switches on and limits drive to Q7. Or at least that's the way I read it. I haven't tested the poor thing with a screwdriver--just don't have the heart (or the time).
So many ideas...so little time.
Did I mention the Difference Engine?
Hagrid: "I shouldn't have said that!"
Or how about the...
I'd better stop while I'm ahead. I can't even keep up with what I've got on the burner now. (<i>Grumble, grumble...mutter, mutter...</i>)
Grey
Well, I'm glad someone put out a simple, balanced, 2 stage, single-ended amp, which can handle lower impedences.
Thanks to everyone for their advise.
Vince
Thanks to everyone for their advise.
Vince
The Difference Engine was a wonderful premise for a
novel, but it seems that Gibson and Sterling's collaboration
fell short after a couple of chapters.
novel, but it seems that Gibson and Sterling's collaboration
fell short after a couple of chapters.
Aye...'tis why I always write as myself, alone. Too many cooks spoiling the broth, etc...though Niven & Pournelle have managed a tale or two that hang together in spite of being written by a committee. The exception that proves the rule, I think.
Grey
Grey
I agree, Nelson. Seems to me that I read once that one of them writes the crowd scenes, because he's better at that, and the other writes the one-on-one scenes. I don't remember which is which, but I'd be willing to bet that it's Niven that writes the smaller scale stuff; generally the backbone of any story.
The newer stuff with Barnes...I dunno...
Grey
The newer stuff with Barnes...I dunno...
Grey
I can not help myself.The Q5 in the schematics can worse the distorsion beeing close to limitation.I have not done any measurement only simulations.