..And there are those which aren't designed for it, but look beautiful at it...(try 6V6, 150Vp, 150Vs (pentode or triode mode actually), 10 to 15Vp grid drive, load resistance to suit.)
Note also that, with a floating grid, it isn't at 0V. It is, in fact, a few volts below cathode! (This can be proven by alternately connecting the grid to a bias source, then floating it, all the while measuring current.)
Tim
Note also that, with a floating grid, it isn't at 0V. It is, in fact, a few volts below cathode! (This can be proven by alternately connecting the grid to a bias source, then floating it, all the while measuring current.)
Tim
Gabe - John said the leakage through the capacitor (if any exists, it should be VERY VERY small) is the path. Remember, a cap has an insulator between it's plates. If you want to build an amp where your AC coupling is dependant on the leakage through an insultor, be my guest!
In fact, I encourage you to go home, clip all the grid resistors and/or chokes out of every stage in your favorite amp and tell us the result.
Frank is right, this is a waste of time.
In fact, I encourage you to go home, clip all the grid resistors and/or chokes out of every stage in your favorite amp and tell us the result.
Frank is right, this is a waste of time.
Joel said:
$1200 is affordable?
...with 2 each of Magnequest power trfo's, filter chokes, plate chokes, OPT's...and C4S CCS's, ...yes, they are affordable for what you get.
You could always get the Paramours @ $550/pr. They also employ parafeed and CCS loading, and sound quite nice.
DocB and his wife are very nice and generous people that don't deserve the "Barnum" quip.
Joel said:And don't get me started on Magnequest please. $80 chokes?
sheesh.
Let's see, by the time I sourced the materials to make one choke and wound it myself by hand, I could quite easily buy ten of these for the cost of the time alone. I can't quite see how this or the amplifiers sold by Doc Bottlehead are ripoffs. I'd wager no one here could mass produce these amps for a siginificantly lower price. You aren't going to find enough parts in the dumpster to make 100s of these amps.
Hold the horses
Gabe, is it possible you had a really bad day and missed it? I'm told it's on the RCA jack side and not the tube socket.
probably not.
Is it possible the (probably first time) builder screwed up? Wouldn't be the first time.
I contacted a guy who has seen them and he says they do have a grid connection. He knows what he's talking about too.
Tempest in a teapot me thinks. Na, that could never happen at an audio forum.
Cheers
Craig Ryder
Gabe, is it possible you had a really bad day and missed it? I'm told it's on the RCA jack side and not the tube socket.
probably not.
Is it possible the (probably first time) builder screwed up? Wouldn't be the first time.
I contacted a guy who has seen them and he says they do have a grid connection. He knows what he's talking about too.
Tempest in a teapot me thinks. Na, that could never happen at an audio forum.
Cheers
Craig Ryder
Ryder,
WHOOPS!!!! You know something!! You are absolutely right!
DOH!
But I did rewire the Sun amp, bypassing the volume controls and used no grid resistor. Amp still worked fine.
Thanks for pointing that out to me. Yes, I must have been having a bad day at that point. The Bottlehead amps do indeed have a grid resistor to ground. I stand corrected.
When I get back in town I will disconnect it... just to see what happens.
However, As I said above, I did not use one on the Sun amp.
Sy,
And what is wrong with DC NFB and voltage regulated fixed bias? Depending solely on component (tube or transistor)characteristics, quality of capacitors and resistors would be bad engineering... IMHO.
NFB and fixed bias should make an amp more stable, and the output more true to the input... again IMHO.
Gabe
WHOOPS!!!! You know something!! You are absolutely right!
DOH!
But I did rewire the Sun amp, bypassing the volume controls and used no grid resistor. Amp still worked fine.
Thanks for pointing that out to me. Yes, I must have been having a bad day at that point. The Bottlehead amps do indeed have a grid resistor to ground. I stand corrected.
When I get back in town I will disconnect it... just to see what happens.
However, As I said above, I did not use one on the Sun amp.
Sy,
And what is wrong with DC NFB and voltage regulated fixed bias? Depending solely on component (tube or transistor)characteristics, quality of capacitors and resistors would be bad engineering... IMHO.
NFB and fixed bias should make an amp more stable, and the output more true to the input... again IMHO.
Gabe
fdegrove,
Well... skeptic that I am... and being one who has to be absolutely sure... you could have told me that there was such a thing as server fairy dust, as in that IBM commercial, and I would have had to acquire some for myself and try it in order to see for sure that it works.
IOW, I do not even take the word of the RDH or any of the other books I have in my possesion. I try it for myself to be sure.
And no, some were saying that it wouldn't work.
Gabe
Well... skeptic that I am... and being one who has to be absolutely sure... you could have told me that there was such a thing as server fairy dust, as in that IBM commercial, and I would have had to acquire some for myself and try it in order to see for sure that it works.
IOW, I do not even take the word of the RDH or any of the other books I have in my possesion. I try it for myself to be sure.
And no, some were saying that it wouldn't work.
Gabe
ARCANGEL .
Hi Gabe,
If you go through the whole thread you will notice I toyed with this too.
There is nothing there that defies neither logic nor physics...bar one thing,you need to consider the termination of your transfer line, AKA transmission line.
Not terminating at either end will yield a frequency response that will be left to the elements, if you know what I mean.
I realise that at least one member said that it won't work,I know,and to some extend I agree.
Looking at things in an isolated manner,naturally this can't possibly work...looking at the interaction between all that is interconnected I say it can work.
Imagine,if you like a preamp with a 100K bleeder R at the output followed by an amp with an input R of 100K...We now have the preamp looking at a 50K input impedance.
What happens when I now clip the the 100K R out at the amp?
Will it still work?
Yes,it will.
Will I now hear a difference in sound?
Quite likely...
Will my amp now change frequency response with whatever I hook up?
Unfortunately,yes!
Try it out for yourself and tell me what you hear.Moreover,I'm sure you're equipped to do some measurements.
That should straighten it out.
Cheers,
Hi Gabe,
If you go through the whole thread you will notice I toyed with this too.
There is nothing there that defies neither logic nor physics...bar one thing,you need to consider the termination of your transfer line, AKA transmission line.
Not terminating at either end will yield a frequency response that will be left to the elements, if you know what I mean.
I realise that at least one member said that it won't work,I know,and to some extend I agree.
Looking at things in an isolated manner,naturally this can't possibly work...looking at the interaction between all that is interconnected I say it can work.
Imagine,if you like a preamp with a 100K bleeder R at the output followed by an amp with an input R of 100K...We now have the preamp looking at a 50K input impedance.
What happens when I now clip the the 100K R out at the amp?
Will it still work?
Yes,it will.
Will I now hear a difference in sound?
Quite likely...
Will my amp now change frequency response with whatever I hook up?
Unfortunately,yes!
Try it out for yourself and tell me what you hear.Moreover,I'm sure you're equipped to do some measurements.
That should straighten it out.
Cheers,
Re: ARCANGEL .
Note that, in this case (and I'll use it as a case of 'everything is different'), the reduced load will 1. reduce delivered output power (well there's no load, is there? ), 2. increase output voltage, and 3. reduce distortion.
What I'd like to know is why this thread got so long...
Tim
fdegrove said:
Note that, in this case (and I'll use it as a case of 'everything is different'), the reduced load will 1. reduce delivered output power (well there's no load, is there?
), 2. increase output voltage, and 3. reduce distortion.What I'd like to know is why this thread got so long...
Tim
You think THIS is long? You should check out the capacitor one.
It is up to six pages now! It's still going on!
I would think that there would be only a small increase in response in the low end, because the capacitor's reactance would see a very high impedance that is the grid.
As for loss of power... how????? If anything, the amp would clip sooner, because the preamp sees an extremely small load (the very high impedance of the grid), the preamps output being a little higher. So... I will just do it for myself, report on it on my site, and wallow in my own ignorance... or edification... whichever one may want to deem it as.
I will end it here since it does seem to be going "ad nauseum".
Gabe
It is up to six pages now! It's still going on!
I would think that there would be only a small increase in response in the low end, because the capacitor's reactance would see a very high impedance that is the grid.
As for loss of power... how????? If anything, the amp would clip sooner, because the preamp sees an extremely small load (the very high impedance of the grid), the preamps output being a little higher. So... I will just do it for myself, report on it on my site, and wallow in my own ignorance... or edification... whichever one may want to deem it as.
I will end it here since it does seem to be going "ad nauseum".
Gabe
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