[Bertie the Bunyip]

Eeyore wrote in
:



Arny Krueger wrote:

"Eeyore" wrote in
Arny Krueger wrote:
"Eeyore" wrote
Phil Allison wrote:
"Eeyore"

In fact I've a sort of grudge to bear in fact.

** So THAT is what " Eeyore " really is -

a bear with some sort of grudge ??

Long story. Only a small grudge really. I must learn
to lie in job interviews too.

** Oh - that job Doug got with Soundcraft ?

Uhuh.


He did the power amp stage of their "PowerStation".

Joke isn't it ?

What's wrong with it?

Do tell!

It's fairly 'routine'. That's the joke.

IOW, despite the use of a "big name" designer, the wine came out
tasting pretty ordinaire.

Is it class G?

The one I saw was just A/B.


I notice that Self makes some heavy claims about a proprietary
implemention of class G.

I haven't heard that. I'd be curious to know how it can be made
proprietary !

Graham




fjukkwit netkkop


Bertie

[Arny Krueger]

"Eeyore" wrote in
message
Arny Krueger wrote:

"Eeyore" wrote
in
Arny Krueger wrote:
"Eeyore" wrote
Phil Allison wrote:
"Eeyore"

In fact I've a sort of grudge to bear in fact.

** So THAT is what " Eeyore " really is -

a bear with some sort of grudge ??

Long story. Only a small grudge really. I must learn
to lie in job interviews too.

** Oh - that job Doug got with Soundcraft ?

Uhuh.


He did the power amp stage of their "PowerStation".

Joke isn't it ?

What's wrong with it?

Do tell!

It's fairly 'routine'. That's the joke.

IOW, despite the use of a "big name" designer, the wine
came out tasting pretty ordinaire.

Is it class G?

The one I saw was just A/B.


I notice that Self makes some heavy claims about a
proprietary implemention of class G.

I haven't heard that. I'd be curious to know how it can
be made proprietary !


http://www.dself.dsl.pipex.com/ampins/classg/g.htm


"Class-G is now out and about. So what has changed? This would be easier to
answer if there had been more published on the technology; as it is I have
to rely pretty much on my own research. I found that Schottky power diodes
have eliminated the commutation-diode glitching. Having peeled this skin
from the distortion onion, linearity was still signficantly poorer than a
Blameless Class-B design. This proved to be due to Early effect in the
output stage devices, stemming from the sudden changes in collector voltage
they experience in Class-G operation. I had my own ideas about how to deal
with this, and you can read all in Electronics World for Dec 2001 and Jan,
Feb 2002. There is a fully worked-out design, and even a PCB available to
ease building it."

The "Early Effect" amounts to being an increase in beta with increased VCE.
The happens in a class-G amp when the power supply voltage is switched to a
higher voltage.

[Eeyore]

Arny Krueger wrote:

"Eeyore" wrote
Arny Krueger wrote:

As my distortion measuring gear progressed to residuals
in below 0.01% there was always a mixed bag of
measurable differences. But they were arguably quite
small, given that its often darn hard to hear distortion
below 0.1% or so.

I had a 'revalation' that blew away that idea about 30
years ago.

Do tell.

I made my last try at making small amounts of nonlinear distortion audible
about 5 years ago, and the 0.1% number was the fruit of that effort. My
results aren't that dissimilar from those found in J. Robert Stuart
(Meridian Audio), "Digital Audio for the Future", Audio, 3/98 pp 30-37.
Stuart isn't exactly conservative on this topic. I know of nobody credible
who has claimed lower thresholds for audibilty.

In my case my I was comparing the H-H TPA 50 amplifier ( a fairly classic A/B
design of its era and quite widely used in pro-audio - including the BBC )
with ~ 0.1% THD on the spec sheet with a friend's recently assembled kit
ampliifer using Crimson Elektrik modules. These used a rather more 'state of
the art' design with the then new high speed Japanese output devices ( the H-H
used Motorola darlingtons ).

Lets just say the difference wasn't subtle !

The H-H sounded gritty by comparison to the much smoother Crimson.

Graham

[Eeyore]

Arny Krueger wrote:

"Eeyore" wrote
Arny Krueger wrote:
"Eeyore" wrote
Arny Krueger wrote:
"Eeyore" wrote

My intention is to entirely eliminate this with a kind
of 'hybrid' output stage.

How? Other than class-A you'd need to come up with
some kind of Gm-halving circuit.

It is a 'form' of Class A that indeed meets the classic
definition but without the very high idle current. It
involves quite a radical rethink of the output stage.

In the past the usual approach to this has been to use a
bias circuit that keeps the output devices from ever
turning fully off.

It's that kind of thing.

What do you know about previous examples of this.

Used in some Japanese amps from maybe the late 70s and early 80s.

I've just generally heard that they hadn't been brilliantly
succesful.

I think the usual phrase used to describe this is "sliding bias".

Yes.


It seems to me that sliding bias can make power amps less reliable, by
turning minor faults into situations where lots of power is dissipated in
the output stage. The trick might be to back out the sliding bias feature
when things start going awry, like a shorted load or some such.

I couldn't comment without seeing a schematic really. I can't imagine why
that should be so.

You haven't come across any then ?

Graham

[Scott Dorsey]

Trevor Wilson wrote:

**True. What you said was bull****. Now, pay attention to my words. Focus
on: "Otherwise identical". Also focus on: "Poorly designed". If you, like I
have, taken a well designed Class A/B amp and cranked the bias current up to
100 Watts Class A, you will have noted no sonic differences between the
Class A/B operation and the Class A operation. OTOH, I have taken crappily
designed Class A/B amps and cranked the bias up to high levels of Class A
and found significant sonic improvements from doing so.

No, that bears no connection with what I said. I said that if you take a
class B amplifier and crank the gain up into the A/B range, that the sound
quality may be subjectively worse even though the THD is reduced. I said
nothing at ALL about full class A operation.

IOW: The design is more important than the Class of operation. Class A will
help a bad design and, at best, do nothing to a good design.

Absolutely.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Eeyore]

Arny Krueger wrote:

"Eeyore" wrote in
Arny Krueger wrote:

I notice that Self makes some heavy claims about a
proprietary implemention of class G.

I haven't heard that. I'd be curious to know how it can
be made proprietary !

http://www.dself.dsl.pipex.com/ampins/classg/g.htm

"Class-G is now out and about. So what has changed? This would be easier to
answer if there had been more published on the technology; as it is I have
to rely pretty much on my own research. I found that Schottky power diodes
have eliminated the commutation-diode glitching. Having peeled this skin
from the distortion onion, linearity was still signficantly poorer than a
Blameless Class-B design. This proved to be due to Early effect in the
output stage devices, stemming from the sudden changes in collector voltage
they experience in Class-G operation. I had my own ideas about how to deal
with this, and you can read all in Electronics World for Dec 2001 and Jan,
Feb 2002. There is a fully worked-out design, and even a PCB available to
ease building it."

The "Early Effect" amounts to being an increase in beta with increased VCE.
The happens in a class-G amp when the power supply voltage is switched to a
higher voltage.

I notice that his ideas on the matter can only apparently be read in the copies
of EW mentioned.

His does pontificate a heck of alot !

Graham

[Scott Dorsey]

Eeyore wrote:

My current ruse is to avoid *any* global NFB. Not because it's important but for
pure marketing bull**** factor.

If this is the case, look at some of the Nelson Pass designs. No overall
network feedback, output stages are inexpensive FETs biased well into class A,
and in spite of all the buzzwords, they sound damn good. I haven't run
distortion spectra on any but I'd bet you could make a good guess by looking
at the output device curves. (This being the case, I would suspect that
the particular MOSFETS you chose would make a substantial difference in
the sound.... negative feedback would do a lot to reduce those differences).
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

tony sayer wrote:

Anyone ever made a good commercially viable class D amp?...

Everyone and his brother has. A huge number of portable devices, from
iPods to laptops, are using class D stages because of the low power
consumption. You're also starting to see them inside a lot of powered
speakers. Tripath and TI are some of the popular manufacturers.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Eeyore]

Scott Dorsey wrote:

Eeyore wrote:

My current ruse is to avoid *any* global NFB. Not because it's important but for
pure marketing bull**** factor.

If this is the case, look at some of the Nelson Pass designs.

I have actually looked at a couple of the explanatory documents on his site but I'm
following a very different path.


No overall
network feedback, output stages are inexpensive FETs biased well into class A,
and in spite of all the buzzwords, they sound damn good. I haven't run
distortion spectra on any but I'd bet you could make a good guess by looking
at the output device curves. (This being the case, I would suspect that
the particular MOSFETS you chose would make a substantial difference in
the sound.... negative feedback would do a lot to reduce those differences).

The output stage I have in mind should totally eliminate these classic problems. I'd
love to say how but I think it may be patentable.

Graham

[Eeyore]

Scott Dorsey wrote:

tony sayer wrote:

Anyone ever made a good commercially viable class D amp?...

Everyone and his brother has. A huge number of portable devices, from
iPods to laptops, are using class D stages because of the low power
consumption. You're also starting to see them inside a lot of powered
speakers. Tripath and TI are some of the popular manufacturers.

I keep hearing good things about Hypex btw.

Graham

[Arny Krueger]

"Eeyore" wrote in
message
Arny Krueger wrote:

"Eeyore" wrote
Arny Krueger wrote:

As my distortion measuring gear progressed to residuals
in below 0.01% there was always a mixed bag of
measurable differences. But they were arguably quite
small, given that its often darn hard to hear
distortion below 0.1% or so.

I had a 'revalation' that blew away that idea about 30
years ago.

Do tell.

I made my last try at making small amounts of nonlinear
distortion audible about 5 years ago, and the 0.1%
number was the fruit of that effort. My results aren't
that dissimilar from those found in J. Robert Stuart
(Meridian Audio), "Digital Audio for the Future", Audio,
3/98 pp 30-37. Stuart isn't exactly conservative on this
topic. I know of nobody credible who has claimed lower
thresholds for audibilty.

In my case my I was comparing the H-H TPA 50 amplifier (
a fairly classic A/B design of its era and quite widely
used in pro-audio - including the BBC ) with ~ 0.1% THD
on the spec sheet with a friend's recently assembled kit
ampliifer using Crimson Elektrik modules. These used a
rather more 'state of the art' design with the then new
high speed Japanese output devices ( the H-H used
Motorola darlingtons ).

Lets just say the difference wasn't subtle !

The H-H sounded gritty by comparison to the much smoother
Crimson.

I had to search high and low to find much out about H-H brand equipment.
Apparently they were popular in the late 70s. I wouldn't try to generalize
very much related to just one sample of such an ancient obscure piece.

[hank alrich]

Trevor Wilson wrote:

**Bull****. Only poorly deisgned Class A/B amps sound significantly worse
than an otherwise identical Class A amp. Pay careful attention to my words:
"Otherwise identical".

Guess who this asshole is.

--
ha

[hank alrich]

Scott Dorsey wrote:

**Bull****. Only poorly deisgned Class A/B amps sound significantly worse
than an otherwise identical Class A amp. Pay careful attention to my words:
"Otherwise identical".

That's not what I said. That is not at ALL what I said.

This is obviously Filly Assilon. It can neither hear nor read with its
head in there.

--
ha

[Scott Dorsey]

Arny Krueger wrote:
"Eeyore" wrote in

Oh there is, but since a classic Class A output has such
high standing dissipation you use more devices in
parallel and you're actually working them at lower
currents than in A/B.

I think I saw the effects of beta fall-off in my testing. I was working
with 8 devices up and 8 devices down. VCC was about 80 volts. The devices
were complements from the MJE 1502x series.

Admittedly, one go add enough devices so that beta fall-off wouldn't be an
issue.

If you don't mind non-complementary output stages, there are truly
gargantuan MOSFETs available today for electric motor control applications.
Most aren't designed for linearity, but some careful selection may help.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Eeyore]

hank alrich wrote:

Scott Dorsey wrote:

**Bull****. Only poorly deisgned Class A/B amps sound significantly worse
than an otherwise identical Class A amp. Pay careful attention to my words:
"Otherwise identical".

That's not what I said. That is not at ALL what I said.

This is obviously Filly Assilon. It can neither hear nor read with its
head in there.

Actually it was another Australian !

You've comitted the cardinal sin now. Prepare to be roasted.

Graham

[Eeyore]

Scott Dorsey wrote:

Arny Krueger wrote:
"Eeyore" wrote in

Oh there is, but since a classic Class A output has such
high standing dissipation you use more devices in
parallel and you're actually working them at lower
currents than in A/B.

I think I saw the effects of beta fall-off in my testing. I was working
with 8 devices up and 8 devices down. VCC was about 80 volts. The devices
were complements from the MJE 1502x series.

Admittedly, one go add enough devices so that beta fall-off wouldn't be an
issue.

If you don't mind non-complementary output stages, there are truly
gargantuan MOSFETs available today for electric motor control applications.
Most aren't designed for linearity, but some careful selection may help.

I'm still fond of lateral mosfets. I've got a couple of amps here ( of my own
design in fact ) with 12 Hitachi devices per channel.

Graham

[Arny Krueger]

"Eeyore" wrote in
message
Arny Krueger wrote:

"Eeyore" wrote
Arny Krueger wrote:
"Eeyore" wrote
Arny Krueger wrote:
"Eeyore"
wrote

My intention is to entirely eliminate this with a
kind of 'hybrid' output stage.

How? Other than class-A you'd need to come up with
some kind of Gm-halving circuit.

It is a 'form' of Class A that indeed meets the
classic definition but without the very high idle
current. It involves quite a radical rethink of the
output stage.

In the past the usual approach to this has been to use
a bias circuit that keeps the output devices from ever
turning fully off.

It's that kind of thing.

What do you know about previous examples of this.

Used in some Japanese amps from maybe the late 70s and
early 80s.

I've just generally heard that they hadn't been
brilliantly succesful.

I think the usual phrase used to describe this is
"sliding bias".

Yes.


It seems to me that sliding bias can make power amps
less reliable, by turning minor faults into situations
where lots of power is dissipated in the output stage.
The trick might be to back out the sliding bias feature
when things start going awry, like a shorted load or
some such.

I couldn't comment without seeing a schematic really. I
can't imagine why that should be so.

You haven't come across any then ?

I'm pretty sure I've heard some Technics amps with sliding bias. They sold
them in appliance stores around here in the days of. I seem to recall
their advertising buzzword was "New Class A" or some such.

[Arny Krueger]

"Eeyore" wrote in
message
Arny Krueger wrote:

"Eeyore" wrote
in
Arny Krueger wrote:

I notice that Self makes some heavy claims about a
proprietary implemention of class G.

I haven't heard that. I'd be curious to know how it can
be made proprietary !

http://www.dself.dsl.pipex.com/ampins/classg/g.htm

"Class-G is now out and about. So what has changed? This
would be easier to answer if there had been more
published on the technology; as it is I have to rely
pretty much on my own research. I found that Schottky
power diodes have eliminated the commutation-diode
glitching. Having peeled this skin from the distortion
onion, linearity was still signficantly poorer than a
Blameless Class-B design. This proved to be due to Early
effect in the output stage devices, stemming from the
sudden changes in collector voltage they experience in
Class-G operation. I had my own ideas about how to deal
with this, and you can read all in Electronics World for
Dec 2001 and Jan, Feb 2002. There is a fully worked-out
design, and even a PCB available to ease building it."

The "Early Effect" amounts to being an increase in beta
with increased VCE. The happens in a class-G amp when
the power supply voltage is switched to a higher voltage.

I notice that his ideas on the matter can only apparently
be read in the copies of EW mentioned.

His does pontificate a heck of alot !

I believe that Self also added some stuff on his allegedly new Class G
technology in his book.

"Audio Power Amplifier Design Handbook, Fourth Edition" It's about $50 in
paperback from Amazon.

[Ruud Broens]

wow.
Jenn, you can see that RAO has it's redeeming periods :-)


impressed
R.

[Harry Lavo]

"Arny Krueger" wrote in message
. ..
"Eeyore" wrote in
message
Arny Krueger wrote:

"Eeyore" wrote
Arny Krueger wrote:
"Eeyore" wrote
Arny Krueger wrote:
"Eeyore"
wrote

My intention is to entirely eliminate this with a
kind of 'hybrid' output stage.

How? Other than class-A you'd need to come up with
some kind of Gm-halving circuit.

It is a 'form' of Class A that indeed meets the
classic definition but without the very high idle
current. It involves quite a radical rethink of the
output stage.

In the past the usual approach to this has been to use
a bias circuit that keeps the output devices from ever
turning fully off.

It's that kind of thing.

What do you know about previous examples of this.

Used in some Japanese amps from maybe the late 70s and
early 80s.

I've just generally heard that they hadn't been
brilliantly succesful.

I think the usual phrase used to describe this is
"sliding bias".

Yes.


It seems to me that sliding bias can make power amps
less reliable, by turning minor faults into situations
where lots of power is dissipated in the output stage.
The trick might be to back out the sliding bias feature
when things start going awry, like a shorted load or
some such.

I couldn't comment without seeing a schematic really. I
can't imagine why that should be so.

You haven't come across any then ?

I'm pretty sure I've heard some Technics amps with sliding bias. They sold
them in appliance stores around here in the days of. I seem to recall
their advertising buzzword was "New Class A" or some such.

If that was sliding bias, then my experience with "New Class A" has been
favorable. My lady friend had a Technics Receiver featuring same from the
early eighties, driving KLH speakers which I'm fairly familiar with. I've
listened to full symphony orchestra with that combo, and I'd have to say the
receivers sound was more "sweet" and lifelike than any other receiver I've
heard from the eighties (including Marantz and Yamaha). It sounded far less
"bright", and far more like a current high-quality amplifier.

[Ruud Broens]

"Eeyore" wrote in message
...
:
:
: Arny Krueger wrote:
:
: "Eeyore" wrote
: Arny Krueger wrote:
:
: As my distortion measuring gear progressed to residuals
: in below 0.01% there was always a mixed bag of
: measurable differences. But they were arguably quite
: small, given that its often darn hard to hear distortion
: below 0.1% or so.
:
: I had a 'revalation' that blew away that idea about 30
: years ago.
:
: Do tell.
:
: I made my last try at making small amounts of nonlinear distortion audible
: about 5 years ago, and the 0.1% number was the fruit of that effort. My
: results aren't that dissimilar from those found in J. Robert Stuart
: (Meridian Audio), "Digital Audio for the Future", Audio, 3/98 pp 30-37.
: Stuart isn't exactly conservative on this topic. I know of nobody credible
: who has claimed lower thresholds for audibilty.
:
: In my case my I was comparing the H-H TPA 50 amplifier ( a fairly classic A/B
: design of its era and quite widely used in pro-audio - including the BBC )
: with ~ 0.1% THD on the spec sheet with a friend's recently assembled kit
: ampliifer using Crimson Elektrik modules. These used a rather more 'state of
: the art' design with the then new high speed Japanese output devices ( the H-H
: used Motorola darlingtons ).
:
: Lets just say the difference wasn't subtle !
:
: The H-H sounded gritty by comparison to the much smoother Crimson.
:
: Graham
:
The Crimson Elektrik modules with the quad 405 like cooling blocks
yeah, didn't they advertise in the Wireless World ?
Rudy

[Sander deWaal]

Eeyore said:


If you don't mind non-complementary output stages, there are truly
gargantuan MOSFETs available today for electric motor control applications.
Most aren't designed for linearity, but some careful selection may help.


I'm still fond of lateral mosfets. I've got a couple of amps here ( of my own
design in fact ) with 12 Hitachi devices per channel.


If you're referring to Hitachi 2SK135/2SJ50s, they are *vertical*
MOSFETs.
My hybrid designs use them exclusively (yep, still have a stash of the
originals.)

Beware of Chinese copies BTW!

--
"Due knot trussed yore spell chequer two fined awl miss steaks."

[Sander deWaal]

Eeyore said:


What do you know about previous examples of this. I've just generally heard
that they hadn't been brilliantly succesful.


Technics used something like that, named class AA or somesuch.

Even after hours of operation, they were useful as champagne coolers.

--
"Due knot trussed yore spell chequer two fined awl miss steaks."

[Sander deWaal]

tony sayer said:


Anyone ever made a good commercially viable class D amp?...


www.hypex.nl

http://www.powersoft.it/index.php?_view_lang=en

--
"Due knot trussed yore spell chequer two fined awl miss steaks."

[tony sayer]

In article , Arny Krueger
writes
"Eeyore" wrote in
message
Arny Krueger wrote:

"Eeyore" wrote
Arny Krueger wrote:

As my distortion measuring gear progressed to residuals
in below 0.01% there was always a mixed bag of
measurable differences. But they were arguably quite
small, given that its often darn hard to hear
distortion below 0.1% or so.

I had a 'revalation' that blew away that idea about 30
years ago.

Do tell.

I made my last try at making small amounts of nonlinear
distortion audible about 5 years ago, and the 0.1%
number was the fruit of that effort. My results aren't
that dissimilar from those found in J. Robert Stuart
(Meridian Audio), "Digital Audio for the Future", Audio,
3/98 pp 30-37. Stuart isn't exactly conservative on this
topic. I know of nobody credible who has claimed lower
thresholds for audibilty.

In my case my I was comparing the H-H TPA 50 amplifier (
a fairly classic A/B design of its era and quite widely
used in pro-audio - including the BBC ) with ~ 0.1% THD
on the spec sheet with a friend's recently assembled kit
ampliifer using Crimson Elektrik modules. These used a
rather more 'state of the art' design with the then new
high speed Japanese output devices ( the H-H used
Motorola darlingtons ).

Lets just say the difference wasn't subtle !

The H-H sounded gritty by comparison to the much smoother
Crimson.

I had to search high and low to find much out about H-H brand equipment.
Apparently they were popular in the late 70s. I wouldn't try to generalize
very much related to just one sample of such an ancient obscure piece.



I recall them and they did sound very rough. But they were mainly used
for PA and such applications......
--
Tony Sayer

[Sander deWaal]

Stuart Krivis said:

I keep hearing good things about Hypex btw.


Hypex is pretty much the only one I haven't heard bad things about
anyway. :-)


Hypex *is* good, in fact they're indistinguishable to most listeners
in a single blind test we did recently with some DIY enthousiasts.

This doesn't prove anything, but at least it says something about
their quality.

These were the UcD400AD versions, tweaked up a little by Sander Sassen
[ http://www.hardwareanalysis.com ]

A review can be found he
http://www.hardwareanalysis.com/content/article/1822/

--
"Due knot trussed yore spell chequer two fined awl miss steaks."

[Eeyore]

Harry Lavo wrote:

"Arny Krueger" wrote in message
"Eeyore" wrote
Arny Krueger wrote:
"Eeyore" wrote
Arny Krueger wrote:

In the past the usual approach to this has been to use
a bias circuit that keeps the output devices from ever
turning fully off.

It's that kind of thing.

What do you know about previous examples of this.

Used in some Japanese amps from maybe the late 70s and
early 80s.

I've just generally heard that they hadn't been
brilliantly succesful.

I think the usual phrase used to describe this is
"sliding bias".

Yes.


It seems to me that sliding bias can make power amps
less reliable, by turning minor faults into situations
where lots of power is dissipated in the output stage.
The trick might be to back out the sliding bias feature
when things start going awry, like a shorted load or
some such.

I couldn't comment without seeing a schematic really. I
can't imagine why that should be so.

You haven't come across any then ?

I'm pretty sure I've heard some Technics amps with sliding bias. They sold
them in appliance stores around here in the days of. I seem to recall
their advertising buzzword was "New Class A" or some such.

If that was sliding bias, then my experience with "New Class A" has been
favorable. My lady friend had a Technics Receiver featuring same from the
early eighties, driving KLH speakers which I'm fairly familiar with. I've
listened to full symphony orchestra with that combo, and I'd have to say the
receivers sound was more "sweet" and lifelike than any other receiver I've
heard from the eighties (including Marantz and Yamaha). It sounded far less
"bright", and far more like a current high-quality amplifier.

That sounds encouraging. I can imagine it might have that effect.

Graham

[Eeyore]

Ruud Broens wrote:

"Eeyore" wrote in message
: Arny Krueger wrote:
: "Eeyore" wrote
: Arny Krueger wrote:
:
: As my distortion measuring gear progressed to residuals
: in below 0.01% there was always a mixed bag of
: measurable differences. But they were arguably quite
: small, given that its often darn hard to hear distortion
: below 0.1% or so.
:
: I had a 'revalation' that blew away that idea about 30
: years ago.
:
: Do tell.
:
: I made my last try at making small amounts of nonlinear distortion audible
: about 5 years ago, and the 0.1% number was the fruit of that effort. My
: results aren't that dissimilar from those found in J. Robert Stuart
: (Meridian Audio), "Digital Audio for the Future", Audio, 3/98 pp 30-37.
: Stuart isn't exactly conservative on this topic. I know of nobody credible
: who has claimed lower thresholds for audibilty.
:
: In my case my I was comparing the H-H TPA 50 amplifier ( a fairly classic A/B
: design of its era and quite widely used in pro-audio - including the BBC )
: with ~ 0.1% THD on the spec sheet with a friend's recently assembled kit
: ampliifer using Crimson Elektrik modules. These used a rather more 'state of
: the art' design with the then new high speed Japanese output devices ( the H-H
: used Motorola darlingtons ).
:
: Lets just say the difference wasn't subtle !
:
: The H-H sounded gritty by comparison to the much smoother Crimson.
:
: Graham
:
The Crimson Elektrik modules with the quad 405 like cooling blocks
yeah, didn't they advertise in the Wireless World ?

They did indeed Rudy.

Graham

[Eeyore]

tony sayer wrote:

Arny Krueger writes
"Eeyore" wrote in

In my case my I was comparing the H-H TPA 50 amplifier (
a fairly classic A/B design of its era and quite widely
used in pro-audio - including the BBC ) with ~ 0.1% THD
on the spec sheet with a friend's recently assembled kit
ampliifer using Crimson Elektrik modules. These used a
rather more 'state of the art' design with the then new
high speed Japanese output devices ( the H-H used
Motorola darlingtons ).

Lets just say the difference wasn't subtle !

The H-H sounded gritty by comparison to the much smoother
Crimson.

I had to search high and low to find much out about H-H brand equipment.
Apparently they were popular in the late 70s. I wouldn't try to generalize
very much related to just one sample of such an ancient obscure piece.


I recall them and they did sound very rough. But they were mainly used
for PA and such applications......

Many were indeed used in rock PAs simply because they were few British high
power amplifiers of that era but far from exclusively. There was even a special
BBC version of the TPA25.

" There's also a photo of one of the many AIR studio consoles, in their Oxford
Street control rooms. I was interested in the rack of power amplifiers that you
can see to the right of the console. These silver faced units were HH
Electronic TPA100 power amps and what looks like three smaller TPA25 amps at
the bottom of the rack. "

http://www.auroraaudio.net/cgi-bin/d...m=DCForum ID1

Graham

[Eeyore]

Stuart Krivis wrote:

On Tue, 17 Oct 2006 18:12:56 +0100, tony sayer
wrote:

The H-H sounded gritty by comparison to the much smoother
Crimson.

I had to search high and low to find much out about H-H brand equipment.
Apparently they were popular in the late 70s. I wouldn't try to generalize
very much related to just one sample of such an ancient obscure piece.


I recall them and they did sound very rough. But they were mainly used
for PA and such applications......

I seem to remember them as being the real low-budget brand at a local
music store. If you couldn't afford Peavey, they'd try to sell you
some HH stuff.

That's long after HH entered the MI market. The TPAs were their professional
bipolar range. It also says more about the likely mark up on Peavey over here.

Graham

[William Sommerwerck]

There also wasn't very much of a measurable difference and the
differences weren't all positive for class A. For example, running
an output stage in class A can increase distortion, because the
output devices have to run at higher current levels, where the
output transistors might be far less linear.

Might be. Are they? A well-known designer, a friend of mine, is emphatic on
this point -- they aren't. They're more linear. Or rather, less non-linear.

As my distortion measuring gear progressed to residuals below
0.01%, there was always a mixed bag of measurable differences.
But they were arguably quite small, given that its often darn hard
to hear distortion below 0.1% or so.

Probably so, but what types of distortion?

I'm going to try to get Clay Barclay to write something about Crown's
null-testing system. He probably won't, but it's worth a try.

[Eeyore]

William Sommerwerck wrote:

There also wasn't very much of a measurable difference and the
differences weren't all positive for class A. For example, running
an output stage in class A can increase distortion, because the
output devices have to run at higher current levels, where the
output transistors might be far less linear.

Might be. Are they? A well-known designer, a friend of mine, is emphatic on
this point -- they aren't. They're more linear. Or rather, less non-linear.

As my distortion measuring gear progressed to residuals below
0.01%, there was always a mixed bag of measurable differences.
But they were arguably quite small, given that its often darn hard
to hear distortion below 0.1% or so.

Probably so, but what types of distortion?

I'm going to try to get Clay Barclay to write something about Crown's
null-testing system. He probably won't, but it's worth a try.

A key factor here is that crossover distortion is quite high order, hence more
unpleasant to hear.

Graham

[The Demon Prince of Absurdity]

On Tue, 17 Oct 2006 13:59:15 +0000, Bertie the Bunyip did the cha-cha, and
screamed:
Eeyore wrote:
Arny Krueger wrote:
"Trevor Wilson" wrote
"Eeyore" wrote
Trevor Wilson wrote:
"Scott Dorsey" wrote
Trevor Wilson wrote:

**There are plenty of reasons NOT to go pure Class A and very few
to do so.

Other than size and heat?

**Cost, reliability and the fact that high bias Class A/B is lower
in distortion.

Lower ?

**Yup. Self has provided convincing proof of this.

Agreed.

I would hope that this paper would be required reading for any
self-appointed power amp guru:

http://www.dself.dsl.pipex.com/ampins/dipa/dipa.htm

Meow !

Fjukk you you netkkkpiong hypocrite

Hey, if he wants to meow, he can meow. Enlightenment can happen to anyone,
after all.

--
__________________________________________________ ______________________
Hail Eris! TM#5; COOSN-029-06-71069
Cardinal Snarky of the Fannish Inquisition
http://www6.kingdomofloathing.com/login.php
http://www.runescape.com/
No one expects the Fannish Inquisition!
http://groups.yahoo.com/group/Cabal_...y_Pretzel/join

I own "James C Cracked is God!!!":
MID: .com

"Q: How many Bush administration officials does it take to change a
light bulb?
A: None. There is no need to change anything. We made the right decision
to stick with that light bulb. People who say that it is burned out are
giving aid and encouragement to the Forces of Darkness." -- Anon.

"Etymology:
Argumentum ad Septicus : argument to putrefaction. Derived from Septicum
Argumentum : putrefaction of argument.

"Septic \Sep"tic\, Septical \Sep"tic*al\
a. [L. septicus to make putrid: cf. F. septique.]
Having power to promote putrefaction. Of or relating to or
caused by putrefaction." -- Kadaitcha Man, indirectly to
Donald "Skeptic"/"Septic" Alford, in MID:

"I never fail to be amazing" -- Looney Maroon for September 2006 nominee
William Barwell's ego knows no bounds. MID:


"We are most nearly ourselves when we achieve the seriousness of the
child at play." -- Heraclitus

"And thats another mistake on your part. Your 'playing' games on usenet,
and I'm not playing...It has nothing to do with impressing you, it has
more to do with making sure you have the education you'll need to debate.
The debate is no fun for me if you are mentally incapable of it. I'm
giving you an opportunity to educate yourself. That's all." -- A trashy
former virus-writer turned Outer Filth doesn't know if he's playing or
working, in MID: om

"I am incapable of original thoughts" -- Ctrl¤/Alt¤/Del¤ has an honest
moment, in MID:

"But now the end is near. Now Mark Foley comes along and is making
almost all liberal dreams come true and seriously, I'm sorry for it.
See, I believe in karma. I believe what comes around goes around and I
know full well that it's just bad juju to wish such a level of turmoil
and ill upon other humans, warmongering gay-hating maladroits or no, and
that the real path of enlightenment is paved with forgiveness and
progress and white-hot love and turning the other cheek and scotch.

"In fact, Jesus said something about that, I do believe. He said, "Knock
it off already with the warmongering and the hating of each other and
let's all get some wine and party like it's 2012." Then again, he never
saw Karl Rove stab the nation with the dull ice pick of bogus fear. He
never heard George W. Bush describe brutal war and the death of tens of
thousands as "just a comma" in world history.

"Check that. Maybe I'm not so sorry after all." -- Mark Morford,
http://sfgate.com/cgi-bin/article.cg...ve/2006/10/11/
notes101106.DTL&nl=fix
http://tinyurl.com/kusmr

[Eeyore]

Sander deWaal wrote:

Eeyore said:

If you don't mind non-complementary output stages, there are truly
gargantuan MOSFETs available today for electric motor control applications.
Most aren't designed for linearity, but some careful selection may help.

I'm still fond of lateral mosfets. I've got a couple of amps here ( of my own
design in fact ) with 12 Hitachi devices per channel.

If you're referring to Hitachi 2SK135/2SJ50s, they are *vertical*
MOSFETs.
My hybrid designs use them exclusively (yep, still have a stash of the
originals.)

I think you got confused there Sander.

Graham

[Eeyore]

Stuart Krivis wrote:

Eeyore wrote:
Scott Dorsey wrote:
tony sayer wrote:

Anyone ever made a good commercially viable class D amp?...

Everyone and his brother has. A huge number of portable devices, from
iPods to laptops, are using class D stages because of the low power
consumption. You're also starting to see them inside a lot of powered
speakers. Tripath and TI are some of the popular manufacturers.

I keep hearing good things about Hypex btw.


Hypex is pretty much the only one I haven't heard bad things about
anyway. :-)

I've heard good things about them too, but I haven't heard anyone
complain about them, which is not true of most of the others on the
market.

Any ones in particular come in for criticism ? And what kind of criticism ?

Graham

[Eeyore]

Arny Krueger wrote:

"Eeyore" wrote

In my case my I was comparing the H-H TPA 50 amplifier (
a fairly classic A/B design of its era and quite widely
used in pro-audio - including the BBC ) with ~ 0.1% THD
on the spec sheet with a friend's recently assembled kit
ampliifer using Crimson Elektrik modules. These used a
rather more 'state of the art' design with the then new
high speed Japanese output devices ( the H-H used
Motorola darlingtons ).

Lets just say the difference wasn't subtle !

The H-H sounded gritty by comparison to the much smoother
Crimson.

I had to search high and low to find much out about H-H brand equipment.
Apparently they were popular in the late 70s.

Before that in pro-audio.


I wouldn't try to generalize
very much related to just one sample of such an ancient obscure piece.

I had several. It was a classic textbook design btw. They certainly weren't
obscure over here. Everyday wokhorses in fact.

Graham

[Phil Allison]

"Sander deWaal"

If you're referring to Hitachi 2SK135/2SJ50s, they are *vertical*
MOSFETs.


** ******** !!

They are LATERAL mosfets.

I have a nice stash of 2SK176 /2SJ56 son hand, plus some of the newer ones
by Semelab with numbers like BUZ901 and BUZ 906.




........ Phil

[The Demon Prince of Absurdity]

On Wed, 18 Oct 2006 02:27:48 +0000, Bertie the Bunyip did the cha-cha, and
screamed:
The Demon Prince of Absurdity wrote:
On Tue, 17 Oct 2006 13:59:15 +0000, Bertie the Bunyip did the cha-cha,
and screamed:
Eeyore wrote:
Arny Krueger wrote:
"Trevor Wilson" wrote
"Eeyore" wrote
Trevor Wilson wrote:
"Scott Dorsey" wrote
Trevor Wilson wrote:

**There are plenty of reasons NOT to go pure Class A and very
few to do so.

Other than size and heat?

**Cost, reliability and the fact that high bias Class A/B is
lower in distortion.

Lower ?

**Yup. Self has provided convincing proof of this.

Agreed.

I would hope that this paper would be required reading for any
self-appointed power amp guru:

http://www.dself.dsl.pipex.com/ampins/dipa/dipa.htm

Meow !

Fjukk you you netkkkpiong hypocrite

Hey, if he wants to meow, he can meow. Enlightenment can happen to
anyone, after all.

Ahh, you haven't met, have you?

Only by proxy, just over four years ago, when he net.KKKopped me for
x-poasting into one of his favo'wit playpens, alt.redheads. However, my
ISP has since dropped usenet support, so he may find repetition of that
considerably more difficult. Scoville sure did...

--
__________________________________________________ ______________________
Hail Eris! TM#5; COOSN-029-06-71069
Cardinal Snarky of the Fannish Inquisition
http://www6.kingdomofloathing.com/login.php
http://www.runescape.com/
No one expects the Fannish Inquisition!
http://groups.yahoo.com/group/Cabal_...y_Pretzel/join

I own "James C Cracked is God!!!":
MID: .com

"Q: How many Bush administration officials does it take to change a
light bulb?
A: None. There is no need to change anything. We made the right decision
to stick with that light bulb. People who say that it is burned out are
giving aid and encouragement to the Forces of Darkness." -- Anon.

"Etymology:
Argumentum ad Septicus : argument to putrefaction. Derived from Septicum
Argumentum : putrefaction of argument.

"Septic \Sep"tic\, Septical \Sep"tic*al\
a. [L. septicus to make putrid: cf. F. septique.]
Having power to promote putrefaction. Of or relating to or
caused by putrefaction." -- Kadaitcha Man, indirectly to
Donald "Skeptic"/"Septic" Alford, in MID:

"I never fail to be amazing" -- Looney Maroon for September 2006 nominee
William Barwell's ego knows no bounds. MID:


"We are most nearly ourselves when we achieve the seriousness of the
child at play." -- Heraclitus

"And thats another mistake on your part. Your 'playing' games on usenet,
and I'm not playing...It has nothing to do with impressing you, it has
more to do with making sure you have the education you'll need to debate.
The debate is no fun for me if you are mentally incapable of it. I'm
giving you an opportunity to educate yourself. That's all." -- A trashy
former virus-writer turned Outer Filth doesn't know if he's playing or
working, in MID: om

"I am incapable of original thoughts" -- Ctrl¤/Alt¤/Del¤ has an honest
moment, in MID:

"But now the end is near. Now Mark Foley comes along and is making
almost all liberal dreams come true and seriously, I'm sorry for it.
See, I believe in karma. I believe what comes around goes around and I
know full well that it's just bad juju to wish such a level of turmoil
and ill upon other humans, warmongering gay-hating maladroits or no, and
that the real path of enlightenment is paved with forgiveness and
progress and white-hot love and turning the other cheek and scotch.

"In fact, Jesus said something about that, I do believe. He said, "Knock
it off already with the warmongering and the hating of each other and
let's all get some wine and party like it's 2012." Then again, he never
saw Karl Rove stab the nation with the dull ice pick of bogus fear. He
never heard George W. Bush describe brutal war and the death of tens of
thousands as "just a comma" in world history.

"Check that. Maybe I'm not so sorry after all." -- Mark Morford,
http://sfgate.com/cgi-bin/article.cg...ve/2006/10/11/
notes101106.DTL&nl=fix
http://tinyurl.com/kusmr

[tony sayer]

In article , Eeyore rabbitsfriendsandrel
writes


tony sayer wrote:

Arny Krueger writes
"Eeyore" wrote in

In my case my I was comparing the H-H TPA 50 amplifier (
a fairly classic A/B design of its era and quite widely
used in pro-audio - including the BBC ) with ~ 0.1% THD
on the spec sheet with a friend's recently assembled kit
ampliifer using Crimson Elektrik modules. These used a
rather more 'state of the art' design with the then new
high speed Japanese output devices ( the H-H used
Motorola darlingtons ).

Lets just say the difference wasn't subtle !

The H-H sounded gritty by comparison to the much smoother
Crimson.

I had to search high and low to find much out about H-H brand equipment.
Apparently they were popular in the late 70s. I wouldn't try to generalize
very much related to just one sample of such an ancient obscure piece.


I recall them and they did sound very rough. But they were mainly used
for PA and such applications......

Many were indeed used in rock PAs simply because they were few British high
power amplifiers of that era but far from exclusively. There was even a special
BBC version of the TPA25.

" There's also a photo of one of the many AIR studio consoles, in their Oxford
Street control rooms. I was interested in the rack of power amplifiers that you
can see to the right of the console. These silver faced units were HH
Electronic TPA100 power amps and what looks like three smaller TPA25 amps at
the bottom of the rack. "

http://www.auroraaudio.net/cgi-bin/d...format&om=348&
forum=DCForumID1

Graham


Amazing to see just how much vintage Neve gear is around these days and
still in service
--
Tony Sayer

[Dirk Bruere at NeoPax]

The Demon Prince of Absurdity wrote:


I would hope that this paper would be required reading for any
self-appointed power amp guru:

http://www.dself.dsl.pipex.com/ampins/dipa/dipa.htm
Meow !
Fjukk you you netkkkpiong hypocrite
Hey, if he wants to meow, he can meow. Enlightenment can happen to
anyone, after all.
Ahh, you haven't met, have you?

Only by proxy, just over four years ago, when he net.KKKopped me for
x-poasting into one of his favo'wit playpens, alt.redheads. However, my
ISP has since dropped usenet support, so he may find repetition of that
considerably more difficult. Scoville sure did...


Graham - have taken your advice and am about to sign up with Idnet.
BTW, I see you've wound up the mentally disturbed again:-)
Still, they have their uses as we found.

FFF
Dirk

http://www.onetribe.me.uk - The UK's only occult talk show
Presented by Dirk Bruere and Marc Power on ResonanceFM 104.4
http://www.resonancefm.com