lateral mosfets vs. bjts in audio amplifier design

[John Fields]

On Sat, 18 Oct 2008 16:20:30 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

John Fields wrote:

Eeyore wrote:
John Fields wrote:
Eeyore wrote:
mrdarrett@gmail.com wrote:

Do you have schematics on your website?

No. It was DOS Orcad remember. Besides I prefer to keep my circuitry to myself
rather than give it away to every copier.

---
And have it die with you instead of sharing it with the world if you're
not going to commercialize it?

How mean is that?

As mean as you are.

---
Geez, Graham, unlike you, as you well know, over the years I've given
away hundreds, if not thousands, of fully worked out, functional designs
and presented them right here, on these groups, as either formal
drawings roughly conforming to DoD-STD-100C and MIL-HDBK-1006/1 or as
ASCII drawings, when possible.

If some of my designs were commercialized, as I'm sure they were, that
could easily amount to millions of dollars that I've given away.

Are you that mean?

If you knew me in person you'd know otherwise.

I have actually considered putting up some pages online of design tips for audio to help
counter all the shit out there.

---
Then why don't you do it?
---

I seem to have been on the receiving end of "no good deed should go unpunished" for
so long that I'm very cautious now.

---
Strange, that 'cautious' bit, since it seems that even though you get
flamed, for example, for posting gratuitous insults and professing that
you're better than everyone else (which you seem to think are good
deeds) you throw caution to the wind and continually post that kind of
crap.

As far as audio goes I AM better than 99.9% of the competition. I was in a meeting on
Monday regarding a project and sadly had to blow one of the originator's ideas (and he
seemed pretty smart) straight out of the water since he hadn't even properly read a data
sheet it seemed. I'm notorious for finding faults before they get built.

---
In that den of thieves, perhaps, but around here you're also notorious
for professing that your opinions are fact when, in fact, they aren't.

JF

 

[Eeyore]

miso@sushi.com wrote:

Eeyore wrote:
m...@sushi.com wrote:
Eeyore wrote:
Damon Hill wrote:
Eeyore wrote

I used an Audio Precision System One of course. Even then it was barely
above residual.

I back-calcuclated it to 0.0004% ~ -106 SINAD.

The vexation I experienced with low-level distortion measurements
with the few designs I could measure with a Tektronix set was that
noise predominated the measurements. I'm not an engineer, and
design for low noise to match distortion levels is beyond me...
as is the price of an AP system.

But at such low distortion levels, is it worth it?

Everything is worth it.

What exactly does back-calculate mean?

To do the RMS addition calculation backwards.

I have used the AP system 1. It does quite a few tests automatically,
so I would say it is worth it. The 8903 I got was $250 or $300 (I
don't recall exactly) about 6 years ago. APs were substantially more
at the time.

It was an 8903 I probably used once on one project. Clumsy to use and poorer
residuals than AP. I'd have the AP Portable One any day over that. In fact for
simple bench work I prefer the Portable One over the System One because it's
simple 'press button' stuff, no mice to arse about with and it takes up little
room. No other audio measuring set comes close in terms of performance or
convenience.

Graham

The AP system one came out later than the HP 8903B, so you would
expect it to be better.

Maybe. More to the point is that they were designed by the ex-Tek guys. I'd used
Tek's SG505 and AA501 previously. And they were quite OK too.

The portable was later still. The Portable One
has an HP 8903 emulation mode, so I guess you call that clumsy
mode. ;-) Anyway, the HP8903 was good for it's time, but time marches
on.

It has an IEEE interface option I believe.

I really don't like PC based black boxes, so the Portable One would be
my choice for an upgrade.

They are very nice. For a self-contained unit I think they are simply unbeatable. And
so well built too !

The HP 8903 is a back breaker too.

I agree.

The applications group at AP is great.

Always has been with regular app notes.

The system one has this digital
interface on the back. I couldn't quite get it working, called apps,
and the person asked how many people have access to the box. It turns
out the interface was done with simple gates (TTL I think) and often
people blow them up. The bigger the lab, the more likely someone blows
them up and doesn't own up to it. Well, that was the case, but
fortunately the interface chips are in sockets.

I still have my HP 334A. It is the only THD analyzer I've seen with RF
demod. I can't say the box has seen a power cord in a few years, but
you never know.

Many years ago I bought some used B&K and hardly ever used it. Technology marches on
!

Graham

 

[Eeyore]

John Larkin wrote:

Eeyore wrote:
John Larkin wrote:
Eeyore wrote:
John Larkin wrote:
On Fri, 17 Oct 2008 08:27:23 -0700 (PDT), mrdarrett@gmail.com wrote:

Are there any technical advantages that lateral mosfets have over BJTs
in audio amplifier design?

Do lateral mosfets offer lower theoretical THD+N over the entire audio
spectrum than BJTs for instance?

Either needs lots of negative feedback to be really linear, so THD+N
depends on the overall circuit design, not much on the final output
devices.

Maybe for full power but NOT in the vital crossover region.

It's generally easier to drive mosfets than bipolars, but in
audio bandwidths it doesn't matter much. Bipolars, lateral fets,
vertical fets, all can be made to work plenty well enough.

Lateral fets are vastly better for audio. Not least because they match
brilliantly to name another of their features.


I use vertical (conventional power) fets in my NMR gradient amps,
because they are easy to drive fast (directly from a small opamp) and
are (at least some of them are) tough... no second breakdown, easier
to keep biased over temperature.

Also laterals are only made in small quantities and cost a lot.

More audio cargo-cult science.

No.


Bipolars, lateral fets, vertical fets,
all will work as well at audio frequencies if the circuit design is
right. All need negative feedback and sensible bias control.

Matching verticals is a PIG. Laterals do it naturally. Plus biasing them is
kid's stuff.

But why buy expensive, sole-source, 100 watt fets when you can get
cheap, multisourced, 300 watt fets?

(a) they're not 100 watt - in fact one supplier does a dual die 500W device in
TO-3. With an internal copper heat speader btw.

(b) they match like Vfet's don't.

(c) any more silly comments ?

Graham

 

[John Fields]

On Sat, 18 Oct 2008 18:46:56 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

Kevin Aylward wrote:

Eeyore wrote:
Kevin Aylward wrote:
Eeyore wrote:
Kevin Aylward wrote:

Getting silly distortion figures at silly bandwidths is easier with
mosfets, imo...

You're not kidding ! I had < -103dB SINAD back in 1989.

THD gets confusing at those numbers because you can never remember
how many zeroes there are after the decimal point.

I don't remember if I mentioned this not not..but, I measured
0.0018% at the input of the mosfet 1000 on the bench, and 0.0015% at
the output

Not with that Radford shit by any chance ?

Indeed it was.

Explains a few things - LOL ! ;~)

---
What's that supposed to mean?

JF

 

[John Fields]

On Sat, 18 Oct 2008 18:47:40 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

mrdarrett@gmail.com wrote:

Ah, so with a good enough circuit design, HEXFETs can offer that
0.00...01% THD+N too?

Yes I expect so but it may be trickier.

---
How so?

JF

 

[John Fields]

On Sat, 18 Oct 2008 18:44:53 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

Kevin Aylward wrote:

Eeyore wrote:
Damon Hill wrote:
Eeyore wrote

I used an Audio Precision System One of course. Even then it was
barely above residual.

I back-calcuclated it to 0.0004% ~ -106 SINAD.

The vexation I experienced with low-level distortion measurements
with the few designs I could measure with a Tektronix set was that
noise predominated the measurements. I'm not an engineer, and
design for low noise to match distortion levels is beyond me...
as is the price of an AP system.

But at such low distortion levels, is it worth it?

Everything is worth it.

?

If only for the technical challenge and personal reward.

---
Really?

You make those claims and then, conveniently, fail to back them up
because of the restrictions you claim are placed upon you by copyright
and contractual limitations.

I understand your frustration, but I don't think you're important.

If you were, you'd have technically relevant articles published in peer
reviewed journals or, at the very least, cogent discourse posted here,
on USENET.

As it is, all you seem to be intent on doing is promoting yourself as
some sort of audio Guru who claims to greatness but who refuses to
submit proof.

JF

 

[John Larkin]

On Sat, 18 Oct 2008 23:15:21 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

John Larkin wrote:

Eeyore wrote:
John Larkin wrote:
Eeyore wrote:
John Larkin wrote:
On Fri, 17 Oct 2008 08:27:23 -0700 (PDT), mrdarrett@gmail.com wrote:

Are there any technical advantages that lateral mosfets have over BJTs
in audio amplifier design?

Do lateral mosfets offer lower theoretical THD+N over the entire audio
spectrum than BJTs for instance?

Either needs lots of negative feedback to be really linear, so THD+N
depends on the overall circuit design, not much on the final output
devices.

Maybe for full power but NOT in the vital crossover region.

It's generally easier to drive mosfets than bipolars, but in
audio bandwidths it doesn't matter much. Bipolars, lateral fets,
vertical fets, all can be made to work plenty well enough.

Lateral fets are vastly better for audio. Not least because they match
brilliantly to name another of their features.


I use vertical (conventional power) fets in my NMR gradient amps,
because they are easy to drive fast (directly from a small opamp) and
are (at least some of them are) tough... no second breakdown, easier
to keep biased over temperature.

Also laterals are only made in small quantities and cost a lot.

More audio cargo-cult science.

No.


Bipolars, lateral fets, vertical fets,
all will work as well at audio frequencies if the circuit design is
right. All need negative feedback and sensible bias control.

Matching verticals is a PIG. Laterals do it naturally. Plus biasing them is
kid's stuff.

But why buy expensive, sole-source, 100 watt fets when you can get
cheap, multisourced, 300 watt fets?

(a) they're not 100 watt - in fact one supplier does a dual die 500W device in
TO-3. With an internal copper heat speader btw.

ONE supplier indeed. How much does that gadget cost?

And how do you get 500 watts out of a TO-3 can? Put it under a fire
hose?

John

 

[Eeyore]

John Fields wrote:

Eeyore wrote:

As far as audio goes I AM better than 99.9% of the competition. I was in a meeting on
Monday regarding a project and sadly had to blow one of the originator's ideas (and he
seemed pretty smart) straight out of the water since he hadn't even properly read a data
sheet it seemed. I'm notorious for finding faults before they get built.

---
In that den of thieves, perhaps, but around here you're also notorious
for professing that your opinions are fact when, in fact, they aren't.

Find fault with them then !

You're a babe in arms in this discipline.

Graham

 

[Eeyore]

John Fields wrote:

Eeyore wrote:
Kevin Aylward wrote:
Eeyore wrote:
Damon Hill wrote:
Eeyore wrote

I used an Audio Precision System One of course. Even then it was
barely above residual.

I back-calcuclated it to 0.0004% ~ -106 SINAD.

The vexation I experienced with low-level distortion measurements
with the few designs I could measure with a Tektronix set was that
noise predominated the measurements. I'm not an engineer, and
design for low noise to match distortion levels is beyond me...
as is the price of an AP system.

But at such low distortion levels, is it worth it?

Everything is worth it.

?

If only for the technical challenge and personal reward.

---
Really?

You make those claims and then, conveniently, fail to back them up
because of the restrictions you claim are placed upon you by copyright
and contractual limitations.

I understand your frustration, but I don't think you're important.

If you were, you'd have technically relevant articles published in peer
reviewed journals or, at the very least, cogent discourse posted here,
on USENET.

As it is, all you seem to be intent on doing is promoting yourself as
some sort of audio Guru who claims to greatness but who refuses to
submit proof.

Suit yourself. Everything I claim does what it does. All you have to do is
buy one and test it yourself.

I currently have a bit of a quandary. I've been offered 2 serious jobs this
week. And I can't even begin to tell you the background, it's so
complicated.

I've made one decision though. If one outfit wants me it'll be Group
Technical Director.

Graham

 

[Eeyore]

John Fields wrote:

Eeyore wrote:
Kevin Aylward wrote:
Eeyore wrote:
Kevin Aylward wrote:
Eeyore wrote:
Kevin Aylward wrote:

Getting silly distortion figures at silly bandwidths is easier with
mosfets, imo...

You're not kidding ! I had < -103dB SINAD back in 1989.

THD gets confusing at those numbers because you can never remember
how many zeroes there are after the decimal point.

I don't remember if I mentioned this not not..but, I measured
0.0018% at the input of the mosfet 1000 on the bench, and 0.0015% at
the output

Not with that Radford shit by any chance ?

Indeed it was.

Explains a few things - LOL ! ;~)

---
What's that supposed to mean?

Local joke.

Graham

 

[Eeyore]

John Fields wrote:

Eeyore wrote:
mrdarrett@gmail.com wrote:

Ah, so with a good enough circuit design, HEXFETs can offer that
0.00...01% THD+N too?

Yes I expect so but it may be trickier.

---
How so?

Matching for one. I can't believe how dumb you guys are.

I've produced the product, you merely say masty things about it. We have
a word fot that here. TWAT.

Graham

 

[Eeyore]

John Fields wrote:

Eeyore wrote:
Kevin Aylward wrote:
Eeyore wrote:
Damon Hill wrote:
Eeyore wrote

I used an Audio Precision System One of course. Even then it was
barely above residual.

I back-calcuclated it to 0.0004% ~ -106 SINAD.

The vexation I experienced with low-level distortion measurements
with the few designs I could measure with a Tektronix set was that
noise predominated the measurements. I'm not an engineer, and
design for low noise to match distortion levels is beyond me...
as is the price of an AP system.

But at such low distortion levels, is it worth it?

Everything is worth it.

?

If only for the technical challenge and personal reward.

---
Really?

You make those claims and then, conveniently, fail to back them up
because of the restrictions you claim are placed upon you by copyright
and contractual limitations.

Fine. Pay me and I'll do something similar for you and you'll own the
copyright.

<snip bollocks>

Graham

 

[Eeyore]

John Larkin wrote:

Eeyore wrote:
John Larkin wrote:
Eeyore wrote:
John Larkin wrote:
Eeyore wrote:
John Larkin wrote:
On Fri, 17 Oct 2008 08:27:23 -0700 (PDT), mrdarrett@gmail.com wrote:

Are there any technical advantages that lateral mosfets have over BJTs
in audio amplifier design?

Do lateral mosfets offer lower theoretical THD+N over the entire audio
spectrum than BJTs for instance?

Either needs lots of negative feedback to be really linear, so THD+N
depends on the overall circuit design, not much on the final output
devices.

Maybe for full power but NOT in the vital crossover region.

It's generally easier to drive mosfets than bipolars, but in
audio bandwidths it doesn't matter much. Bipolars, lateral fets,
vertical fets, all can be made to work plenty well enough.

Lateral fets are vastly better for audio. Not least because they match
brilliantly to name another of their features.


I use vertical (conventional power) fets in my NMR gradient amps,
because they are easy to drive fast (directly from a small opamp) and
are (at least some of them are) tough... no second breakdown, easier
to keep biased over temperature.

Also laterals are only made in small quantities and cost a lot.

More audio cargo-cult science.

No.


Bipolars, lateral fets, vertical fets,
all will work as well at audio frequencies if the circuit design is
right. All need negative feedback and sensible bias control.

Matching verticals is a PIG. Laterals do it naturally. Plus biasing them is
kid's stuff.

But why buy expensive, sole-source, 100 watt fets when you can get
cheap, multisourced, 300 watt fets?

(a) they're not 100 watt - in fact one supplier does a dual die 500W device in
TO-3. With an internal copper heat speader btw.

ONE supplier indeed. How much does that gadget cost?

And how do you get 500 watts out of a TO-3 can? Put it under a fire
hose?

Ask my friend who makes them.

Graham

 

[John Larkin]

On Sun, 19 Oct 2008 03:26:21 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

John Larkin wrote:

Eeyore wrote:
John Larkin wrote:
Eeyore wrote:
John Larkin wrote:
Eeyore wrote:
John Larkin wrote:
On Fri, 17 Oct 2008 08:27:23 -0700 (PDT), mrdarrett@gmail.com wrote:

Are there any technical advantages that lateral mosfets have over BJTs
in audio amplifier design?

Do lateral mosfets offer lower theoretical THD+N over the entire audio
spectrum than BJTs for instance?

Either needs lots of negative feedback to be really linear, so THD+N
depends on the overall circuit design, not much on the final output
devices.

Maybe for full power but NOT in the vital crossover region.

It's generally easier to drive mosfets than bipolars, but in
audio bandwidths it doesn't matter much. Bipolars, lateral fets,
vertical fets, all can be made to work plenty well enough.

Lateral fets are vastly better for audio. Not least because they match
brilliantly to name another of their features.


I use vertical (conventional power) fets in my NMR gradient amps,
because they are easy to drive fast (directly from a small opamp) and
are (at least some of them are) tough... no second breakdown, easier
to keep biased over temperature.

Also laterals are only made in small quantities and cost a lot.

More audio cargo-cult science.

No.


Bipolars, lateral fets, vertical fets,
all will work as well at audio frequencies if the circuit design is
right. All need negative feedback and sensible bias control.

Matching verticals is a PIG. Laterals do it naturally. Plus biasing them is
kid's stuff.

But why buy expensive, sole-source, 100 watt fets when you can get
cheap, multisourced, 300 watt fets?

(a) they're not 100 watt - in fact one supplier does a dual die 500W device in
TO-3. With an internal copper heat speader btw.

ONE supplier indeed. How much does that gadget cost?

And how do you get 500 watts out of a TO-3 can? Put it under a fire
hose?

Ask my friend who makes them.

You are helpful, as ever.

Given a net theta of 0.5 k/w, chip to world, it runs at about 300C.
Interesting.

John

 

[Phil Allison]

"Eeysore the congenital LIAR "

(a) they're not 100 watt - in fact one supplier does a dual die 500W
device in
TO-3. With an internal copper heat speader btw.

** More arrant nonsense.

The dual chip, TO3 lateral devices are rated at 250 watts.



...... Phil

 

On Oct 18, 12:15 am, Eeyore <rabbitsfriendsandrelati...@hotmail.com>
wrote:

mrdarr...@gmail.com wrote:
Eeyore wrote:
mrdarr...@gmail.com wrote:
Eeyore > > wrote:
mrdarr...@gmail.com wrote:
Are there any technical advantages that lateral mosfets have over BJTs
in audio amplifier design?

Do lateral mosfets offer lower theoretical THD+N over the entire audio
spectrum than BJTs for instance?

Lateral mosfets used individually without NFB have poorer THD (in
simplistic overall terms at full rated power ) than BJTs by a factor of
about 10:1. I measured it !

However their vastly wider bandwidth (combined with suitable driver
circuitry - which is very important) means that the extra 20dB of NFB to
compensate can be applied without any great trouble.

Then you get to the real crux, the crossover area where a lot of low
volume listening is done. Quite simply, the transfer characteristics of
complementary lateral mosfets 'join up' to form an almost flat function at
low current whereas BJTs never do regardless of the bias current and how
hard you try. There are some 'fudges' that can help BJTs but they never
actually eliminate the problem.

And that's why lateral mosfets sound superb.

As I may have said before I designed one with < -100dB SINAD @ full power
@ 1kHz @ 350W. I think with the more advanced CAD tools of today I could
better that now. All I had then was MathCad running under DOS.

Graham

MathCAD under DOS... ouch... 20 years ago? In that case, any patent
you or your employer would have had would be expired by now?

No-one in their right mind patents circuits that are essentially 'obvious' if
only you're clever / smart enough.

Do you have schematics on your website?

No. It was DOS Orcad remember. Besides I prefer to keep my circuitry to myself
rather than give it away to every copier.

And it was developed under contract for a client so it's not really mine to give
away.

Oh well. I'll just borrow a copy of Slone's text then.

Douglas Self didn't care for mosfet amps too much. That's why I posed
my original question.

I don't care for Doug Self too much come to that. Long story.

Graham

You don't care for Doug Self? Then why, in the Class A thread, did
you point the OP to Doug Self's website???

Michael

 

[Kevin Aylward]

John Larkin wrote:

On Fri, 17 Oct 2008 08:27:23 -0700 (PDT), mrdarrett@gmail.com wrote:

Are there any technical advantages that lateral mosfets have over
BJTs in audio amplifier design?

Do lateral mosfets offer lower theoretical THD+N over the entire
audio spectrum than BJTs for instance?

Either needs lots of negative feedback to be really linear, so THD+N
depends on the overall circuit design, not much on the final output
devices. It's generally easier to drive mosfets than bipolars, but in
audio bandwidths it doesn't matter much.

I don't really understand to what aspect you are referring to with this last
phrase. The low drive requirements of mosfets can be the difference between
a slow output triple and a simple low current class A buffer. This has a
major effect in the stabilization of the amp.




Kevin Aylward
www.kevinaylward.co.uk
www.blonddee.co.uk
www.anasoft.co.uk -SuperSpice

 

[Kevin Aylward]

John Larkin wrote:

On Fri, 17 Oct 2008 18:06:47 -0700 (PDT), Allen Bong


Hi Graham,

Is this a good audio amp using HexFET for a starter?

http://users.otenet.gr/~athsam/power_amplifier_45w_hexfet_eng.htm

The driver and output stages use IRF9540 and IRF540 and the opamp is
LF411. THD is 0.2%. Power supply is +/- 30V.

I like it because the PCB design is included.

Allen


Not too bad,

Yes. "not too bad" in the strict sense of the phrase. That is, it is a bad
design, but not so bad as to be totally unusable. However, this does depend
on the definition of "good" somewhat. Assuming we give meaning to the term
"average", then this design can not in any reasonable way be classed as a
"good" or even an average design". It is a quick knock up, that serious
audio designers don't even give a second look to, well except when
commenting on how bad it is.

except for the biasing. Iq could have been set by a
pot+resistor from IC1 pin 4 to 7, and the DC offset trim should be
into the opamp, not fighting it.

A "good" audio amp, imo, will have at most, only one trim pot, and this is
to set the output bias.

The biasing/crossover of this type of circuit is potentially perfect,
in that both stages run at some idle current and signal makes one pick
up,

For very high speed, audiophile performance, this output device
configuration is very poor. The gates of the transistors are connected via
two much speed lag. This usually results in very, large shot through
currents when hit by 100n pulses.

but leaves the opposite side idling. As opposed to a lot of
circuits where conduction on one side actively shuts off the other.

DC bias on the output fets depends on their thresholds, not so good;
closing local loops on the fets (with more opamps) would be better.

Oh...a sure-fire recipe for disaster, if done correctly...It will generate
additional de-stabilising poles. That particular technique can be useful for
reducing LF. distortion, but it does it at the expense of BW, i.e. higher HF
distortion. I would be surprised if this "design" could stand having its HF
IMD compromised any further.

Driving the load from the drains means the amp has a very high
open-loop output impedance,

Well, not so high in this particular case. Assuming a nominal early voltage
of 30V, at 1A would be 30 ohms. Its highly variable though.

which makes it harder to stabilize.

Can be. This is actually a bit subtle. Depending on just what the actuall
compansation is. A correctly designed amp will have a stabilastion load
network, in which case, the stability may well be dominated by a higher
frequency unity gain point In which case, it turns out that the high
frequency UGF of a source follower and a drain ouput is the same.

Flipping things over, driving from sources, makes the crossover
biasing more interesting and costs swing.

At least it's not the same old 40-year vintage class AB thing.

Maybe it should be. It would then, presumably have the output inductor and
|| resistor with an output RC zobel network, that is pretty much mandatory
for stability under all load conditions. I would also suggest looking at a
direct zener clamp on the mosfets.

Unfortunately, I don't have the time to go over the other considerable
shortcomings of this er.. "design"

Kevin Aylward
www.kevinaylward.co.uk
www.blonddee.co.uk
www.anasoft.co.uk -SuperSpice

 

[John Fields]

On Sun, 19 Oct 2008 03:23:18 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

John Fields wrote:

Eeyore wrote:
mrdarrett@gmail.com wrote:

Ah, so with a good enough circuit design, HEXFETs can offer that
0.00...01% THD+N too?

Yes I expect so but it may be trickier.

---
How so?

Matching for one. I can't believe how dumb you guys are.

I've produced the product, you merely say masty things about it. We have
a word fot that here. TWAT.

---
Well, dear boy, I see that, as usual, you've thrown caution to the wind
and fallen into yet another trap.

I asked a simple technical question and, instead of a simple polite
answer, you couldn't help but reply with a gratuitous blanket insult,
"you guys" no doubt referring all of us Left-Pondians.

In addition, you've still provided no information about what "product"
you're referring to or any technical documentation against which any of
your claims could be tested, offering instead lame excuses about not
wanting to infringe copyrights or blaming others for removal of the
documentation.

Finally, I'll add that even if you did manage to, somehow, produce the
documentation I'd suspect that, from your hemming and hawing and
absolute refusal to publish anything concrete, here, for us to view, it
wasn't work done by you in the first place.

JF

 

[John Fields]

On Sun, 19 Oct 2008 03:26:21 +0100, Eeyore
<rabbitsfriendsandrelations@hotmail.com> wrote:

John Larkin wrote:

Eeyore wrote:

(a) they're not 100 watt - in fact one supplier does a dual die 500W device in
TO-3. With an internal copper heat speader btw.

ONE supplier indeed. How much does that gadget cost?

And how do you get 500 watts out of a TO-3 can? Put it under a fire
hose?

Ask my friend who makes them.

---
Of course you're not free to tell us who that might be because the
volume of business that might generate for him would inundate him with
orders he couldn't fill and, therefore, drive him out of business.

How responsible and kind of you.


JF