Spot the Design Error

John Larkin wrote:

--------------------

** Really, so the load's characteristics are irrelevant to your design ?

That's cool .....


The load should be and is irrevelent to the protection algorithm.
Click to expand...

** Absurd.

The load has to be driven, without limiting affecting things adversely.

Never let this jerk get near an audio amp.



...... Phil
 
On Wed, 23 Oct 2019 17:08:17 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:

John Larkin wrote:

--------------------



** Really, so the load's characteristics are irrelevant to your design ?

That's cool .....


The load should be and is irrevelent to the protection algorithm.


** Absurd.

The load has to be driven, without limiting affecting things adversely.

Never let this jerk get near an audio amp.



..... Phil
Click to expand...

What's absurd about shutting down an amp when the fet junction temp
hits some limit? What would be a better protection than that?

There are self-protecting fets that have built-in over-temperature
protection, but the ones that I've tried were bad in other aspects.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
John Larkin wrote:

------------------------
** Really, so the load's characteristics are irrelevant to your design ?

That's cool .....


The load should be and is irrevelent to the protection algorithm.


** Absurd.

The load has to be driven, without limiting affecting things adversely.

Never let this jerk get near an audio amp.



..... Phil


What's absurd about shutting down an amp when the fet junction temp
hits some limit? What would be a better protection than that?



** Planet Larkin must be undergoing an eclipse...
Click to expand...



.... Phil
 
> ** Having that -21V a boost rail make the amp work better and >matches the benefits of the load side bootstrap on the class A >stage.

Are you talking about like Pioneer receivers that had the drivers fed with a higher voltage than the outputs ? And the way I see it there is no reason it has to be class A.
 
jurb...@gmail.com wrote:

---------------------------
** Having that -21V a boost rail make the amp work better and
matches the benefits of the load side bootstrap on the class A >stage.


Are you talking about like Pioneer receivers that had the drivers fed with a > higher voltage than the outputs ?
Click to expand...

* No.

> And the way I see it there is no reason it has to be class A.

** Bootstrapping the class A stage load has been standard practice since the the early 1960s. It linearises that stage and acts just like boosted rail with a current source.

The negative side boost rail is needed because of the "cascode" drive topology. Would not be able to drive the PNP output devices into full conduction at negative voltage peaks otherwise.

The amp meets all specs easily, 0.002% at the 1W level rising to around 0.01% near full power.

The problem is something amp makers almost never spec.



..... Phil
 
Phil Allison <pallison49@gmail.com> wrote in
news:c3c4601b-557f-4b34-99e8-9739832a20e4@googlegroups.com:

jurb...@gmail.com wrote:

---------------------------

** Having that -21V a boost rail make the amp work better and
matches the benefits of the load side bootstrap on the class A
stage.


Are you talking about like Pioneer receivers that had the drivers
fed with a > higher voltage than the outputs ?

* No.

And the way I see it there is no reason it has to be class A.

** Bootstrapping the class A stage load has been standard practice
since the the early 1960s. It linearises that stage and acts just
like boosted rail with a current source.

The negative side boost rail is needed because of the "cascode"
drive topology. Would not be able to drive the PNP output devices
into full conduction at negative voltage peaks otherwise.

The amp meets all specs easily, 0.002% at the 1W level rising to
around 0.01% near full power.

The problem is something amp makers almost never spec.
Click to expand...
I have been a fan of, and have bought Pioneer audio products all my
life. They are a well priced, well engineered, consumer level
product.

I even bought my first LaserDisc player from them. My first
LaserDisc player was a pioneer disc player recovered from a video
game. It was a "Mach I" where the player would no longer deliver the
game's data streams correctly. But it played video discs just fine.
That player contained my first laser optical bench, as it actually
had a nice HeNe 8 inch tube laser in it. And two steerable mirrors,
which I quickly adapted to handle music and put lissajous patterns on
the ceiling with.
 
On Thu, 24 Oct 2019 03:30:24 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:

jurb...@gmail.com wrote:

---------------------------

** Having that -21V a boost rail make the amp work better and
matches the benefits of the load side bootstrap on the class A >stage.


Are you talking about like Pioneer receivers that had the drivers fed with a > higher voltage than the outputs ?

* No.

And the way I see it there is no reason it has to be class A.

** Bootstrapping the class A stage load has been standard practice since the the early 1960s. It linearises that stage and acts just like boosted rail with a current source.

The negative side boost rail is needed because of the "cascode" drive topology. Would not be able to drive the PNP output devices into full conduction at negative voltage peaks otherwise.

The amp meets all specs easily, 0.002% at the 1W level rising to around 0.01% near full power.

The problem is something amp makers almost never spec.



.... Phil
Click to expand...

Crosstalk ?




 
On Thu, 24 Oct 2019 03:30:24 -0700 (PDT), Phil Allison
<pallison49@gmail.com> wrote:

jurb...@gmail.com wrote:

---------------------------

** Having that -21V a boost rail make the amp work better and
matches the benefits of the load side bootstrap on the class A >stage.


Are you talking about like Pioneer receivers that had the drivers fed with a > higher voltage than the outputs ?

* No.

And the way I see it there is no reason it has to be class A.

** Bootstrapping the class A stage load has been standard practice since the the early 1960s. It linearises that stage and acts just like boosted rail with a current source.

The negative side boost rail is needed because of the "cascode" drive topology. Would not be able to drive the PNP output devices into full conduction at negative voltage peaks otherwise.

The amp meets all specs easily, 0.002% at the 1W level rising to around 0.01% near full power.

The problem is something amp makers almost never spec.



.... Phil
Click to expand...

Slew rate ?

The DC-300 was being made at a time when most amplifiers actually did
what they spec'd (typically)





 
John Miles, KE5FX wrote:

------------------------
Obviously the thing oscillates ultrasonically, destroying tweeters
and annoying local dogs. But there are so many possible feedback
loops in that schematic that I don't mind admitting I don't see the
mechanism in question.
Click to expand...

** The Crown DC300A is renowned for being completely stable and "bomb proof".

Plus, despite malicious rumours to the contrary, was not designed to drive the motor in Crown forklift.


Good puzzle, though. I look forward to seeing the answer revealed
at last. It *will* be revealed at last, right?
Click to expand...

** Yes.

And the reveal will probably incriminate a bunch of modern audio amps as well.


..... Phil
 
On Thursday, October 24, 2019 at 12:10:28 PM UTC-7, Phil Allison wrote:
** Hardly likely.
That is what we get here all the time.
Click to expand...

Obviously the thing oscillates ultrasonically, destroying tweeters
and annoying local dogs. But there are so many possible feedback
loops in that schematic that I don't mind admitting I don't see the
mechanism in question.

Good puzzle, though. I look forward to seeing the answer revealed
at last. It *will* be revealed at last, right?

-- john, KE5FX
 
DecadentLinux...@decadence.org wrote:

---------------------------------------
I have been a fan of, and have bought Pioneer audio products all my
life. They are a well priced, well engineered, consumer level
product.
Click to expand...

** Massive non sequitur.

Pioneer = Pee - on - err.



...... Phil
 
Phil Allison <pallison49@gmail.com> wrote in news:24d8b79a-6f48-444b-
8530-5220c0145166@googlegroups.com:

DecadentLinux...@decadence.org wrote:

---------------------------------------

I have been a fan of, and have bought Pioneer audio products all
my
life. They are a well priced, well engineered, consumer level
product.


** Massive non sequitur.

Pioneer = Pee - on - err.


Only time that ever happened, she asked for it.
Click to expand...

Anyway, I did say consumer level product, not audiophool level
gear.

Back then, they were more concerned with low distortion
amplification than Sony or Panasonic or other folks *at the time*
were.
 
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