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Old 4th April 2007, 06:18 AM   #231
EUVL is offline EUVL  Europe
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Link to the above mentioned follower circuit :

http://www.diyaudio.com/forums/showt...43#post1130743

My SUGGESTIONS :

1) Replace :

2SK1529 with IRFP240
3R3W with 0R68 10W (read article on ZV9 at passdiy.com)

2) Parallel as many as you consider adequate for power and output impedance.

3) You would probably need a low impedance follower between signal source and input to the paralleled LU1014s.


Patrick
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Old 4th April 2007, 06:55 AM   #232
juma is offline juma  Germany
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Quote:
Originally posted by Nelson Pass

Well, I don't think I told you those things.
Thanks Mr. Pass !
Point taken.

It's only that this quotation from Aleph 5 owner's manual was such a seductive reading:

"Problems with push-pull amplifier designs associated with crossover distortion have been
discussed elsewhere at length, and one of the primary results is non-monotonicity. Class B
and many AB designs have distortion products that dramatically increase with decreasing
signal. This is reduced greatly by Class A mode, but crossover distortion remains as a lower
order discontinuity in the transfer curve.
For reproducing music as naturally as possible, push-pull symmetric operation is not the best
approach.
Air is not symmetric and does not have a push-pull characteristic. Sound in air is a
perturbation around a positive pressure point. There is only positive pressure, more positive
pressure, and less positive pressure.
Push-pull circuits give rise to odd ordered harmonics, where the phase alignment reflects
compression at both positive and negative peaks and crossover nonlinearity near the zero
point.
Push-pull operation in amplifiers is commonly portrayed by the analogy of a two-man saw
cutting down a tree. Certainly if we are cutting down trees by hand, we would opt for this
method, as it would be much more efficient.
As we are not cutting down trees, I much prefer the image of a violinist holding the bow at one
end with one hand. Only in this manner does the musician gain the degree of control and
precision required to produce the range and subtlety required by music. And so it is with
single-ended amplifiers."


I suppose that I just got carried away with couple of sentences at the end.
Thanks again for all you gave us.
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Old 4th April 2007, 08:05 AM   #233
EUVL is offline EUVL  Europe
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Default Single-Ended Push-Pull Followers

And a push-pull version :

http://www.tubecad.com/2004/blog0023.htm


Patrick
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Old 4th April 2007, 03:27 PM   #234
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Join Date: Feb 2001
Location: Columbia, SC
Quote:
Originally posted by Babowana



My interpretation is that f4 input jfets need no current.
I believe that Papa must be knowing what GR, BL and V mean.
Nevertheless, Papa's circuit says nothing about them.

Papa was half sleeping when he was writing down the manual?
Or, was half lost himself in a reverie?



Don't confuse the current required to drive the device itself and the current it supplies to drive the next stage. While it's true that the input requires very little current to drive, it does require some. Not in the resistive sense, since the resistive aspect is effectively infinite, but in the capacitive aspect because the Gate needs to be charged and discharged.
The Idss of a FET is more related to the current available to drive the next stage than to how hard the device is to drive.

Grey
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Old 4th April 2007, 04:20 PM   #235
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Location: Columbia, SC
Quote:
Originally posted by juma


Thanks Mr. Pass !
Point taken.

It's only that this quotation from Aleph 5 owner's manual was such a seductive reading:

"Problems with push-pull amplifier designs associated with crossover distortion have been
discussed elsewhere at length, and one of the primary results is non-monotonicity. Class B
and many AB designs have distortion products that dramatically increase with decreasing
signal. This is reduced greatly by Class A mode, but crossover distortion remains as a lower
order discontinuity in the transfer curve.
For reproducing music as naturally as possible, push-pull symmetric operation is not the best
approach.
Air is not symmetric and does not have a push-pull characteristic. Sound in air is a
perturbation around a positive pressure point. There is only positive pressure, more positive
pressure, and less positive pressure.
Push-pull circuits give rise to odd ordered harmonics, where the phase alignment reflects
compression at both positive and negative peaks and crossover nonlinearity near the zero
point.
Push-pull operation in amplifiers is commonly portrayed by the analogy of a two-man saw
cutting down a tree. Certainly if we are cutting down trees by hand, we would opt for this
method, as it would be much more efficient.
As we are not cutting down trees, I much prefer the image of a violinist holding the bow at one
end with one hand. Only in this manner does the musician gain the degree of control and
precision required to produce the range and subtlety required by music. And so it is with
single-ended amplifiers."


I suppose that I just got carried away with couple of sentences at the end.
Thanks again for all you gave us.

Don't overlook the necessity to counteract consumer resistance to something different from what they happen to be accustomed to. Given the prevalence of push-pull amps, a single-ended topology is going to have to overcome a certain amount of suspicion to make it in the marketplace.
It's a business, not a religion. Don't get too hung on any one viewpoint.

Grey
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Old 4th April 2007, 08:24 PM   #236
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Personally, I think single-ended is still the most pure way of
doing it, but we do live in a practical world, and I do like to
sell amplifiers.

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Old 4th April 2007, 08:45 PM   #237
jleaman is offline jleaman  Belgium
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Quote:
Originally posted by Nelson Pass
Personally, I think single-ended is still the most pure way of
doing it, but we do live in a practical world, and I do like to
sell amplifiers.

Nelson, re you ok with us going ahead with this group buy ?

J'
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Old 5th April 2007, 12:24 AM   #238
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Quote:
Originally posted by jleaman


Nelson, re you ok with us going ahead with this group buy ?

J'

Group buy Passlabs amps?
Okay, I will consider to join for one.


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Old 5th April 2007, 02:16 AM   #239
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by Babowana



Group buy Passlabs amps?
Okay, I will consider to join for one.



ya naughty boy!

__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
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Old 5th April 2007, 07:39 AM   #240
juma is offline juma  Germany
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Quote:
Originally posted by GRollins
It's a business, not a religion.
God forbid !


Quote:
Originally posted by Nelson Pass
I do like to sell amplifiers.
Well you have to, because you make so many of them. Othwerwise they would pile up and take the whole house, and there would be no room left for speakers !
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