Desoldering pump to avoid

[Trevor Wilson]

On 9/04/2017 3:00 PM, Phil Allison wrote:

Trevor Wilson wrote:


They already sound really good with two pairs of devices each and +/- 60v
rails. They should sound awesome with three pairs and +/- 75v rails. <g


**They won't. If you think they do/will, then you need to get out a lot
more. Those old Hitachi MOSFETs, were very tough and ideally suited to
public address systems. For high quality audio, they suck.


** TW has been pushing this line of *complete bollocks* for decades.

He had a strong commercial motive - he sells expensive Hi-Fi amplifiers ( ME brand) that used BJTs.

**You may care to note that I suggested a comparison with an old Phase
Linear amp. Something which is plentiful and cheap. An old PL will leave
and old Perreaux in the dust. Sound quality-wise.

No mention of ME.

Having worked on some modern Perreaux amps, I am pleased to say that
they do not use the horrible old Hitachi MOSFETs and sound much better
than the old things. They use flat pack MOSFETs.

Fundamentally, they are quite non-linear at anything under an Amp or so
of bias current. The negative tempco of gm means that any fast rising
transients and/or when using low impedance speakers will cause a severe
curtailing of dynamics.


** Utter horse poo.

No such misbehaviour exists with Lateral mosfets used in any real power AMPLIFER in source follower mode.

**I serviced every single one of the tiny number of NRG amps that made
it to Australia. They all blew up. Several times. Worse, when one
channel went, I suspect some kind of oscillation was set up, which took
out the other channel. Every single MOSFET failed. I was never able to
ascertain why the amps failed, just that they did, with monotonous
regularity.

BTW: The MOSFETs were not Hitachi types.


--
Trevor Wilson
www.rageaudio.com.au

 

[Clocky]

On 9/04/2017 6:20 AM, Computer Nerd Kev wrote:

Benderthe.evilrobot <Benderthe.evilrobot@virginmedia.com> wrote:

"Computer Nerd Kev" <not@telling.you.invalid> wrote in message
newsc2m73$1qud$1@gioia.aioe.org...
Trevor Wilson <trevor@spamblockrageaudio.com.au> wrote:
On 5/04/2017 8:41 AM, Trevor Wilson wrote:

**Look for 'flush cutters'. That said, a credible argument can be
mounted to suggest that cutting pins after soldering is not a good idea,
as the stress of cutting may cause a fracture in the joint. Unlikely,
but possible. Best to cut first, then solder.


**Oops. Ignore that. I mis-read your post. A good desoldering iron will
do all you require.

Actually I usually try to cut pins on chips when I'm trying to isolate a
fault and don't want to cut the PCB (or veroboard) tracks. A bit of
component lead is soldered over the break after I'm satisfied. I have
managed it sometimes, but with great difficulty.

Cut tracks with a scalpel held at a sharp angle so the cut edges overlap.
flat it down after with the iron tip - it doesn't take much solder to secure
the join.

I've tried a scalpel and often find I accidently jump over a few
tracks and leave a big slice over the board. Then I have to check
each of the other tracks to make sure I didn't accidently cut
through them, but usually I haven't because I usually have to
make multiple runs over a track with the scalpel to get all the
way through.

It can also be difficult to run solder over small tracks without
risk of lifting them. And on a proper modern PCB you'd have to
scrape off the solder mask.

If cutting the pins is an option, I take it.

The last job I did that involved cutting a number of tracks I used an
engraver bit in a dremel. I've also used 1mm-2mm drill bit to cut
individual tracks. You do need a steady and light touch though.

Cutting pins works and I have used it but that isn't my preferred
method. Everyone will have their own method that works best for them.

 

[Benderthe.evilrobot]

"Computer Nerd Kev" <not@telling.you.invalid> wrote in message
newscbnng$1ao2$1@gioia.aioe.org...

Benderthe.evilrobot <Benderthe.evilrobot@virginmedia.com> wrote:

"Computer Nerd Kev" <not@telling.you.invalid> wrote in message
newsc2m73$1qud$1@gioia.aioe.org...
Trevor Wilson <trevor@spamblockrageaudio.com.au> wrote:
On 5/04/2017 8:41 AM, Trevor Wilson wrote:

**Look for 'flush cutters'. That said, a credible argument can be
mounted to suggest that cutting pins after soldering is not a good
idea,
as the stress of cutting may cause a fracture in the joint. Unlikely,
but possible. Best to cut first, then solder.


**Oops. Ignore that. I mis-read your post. A good desoldering iron will
do all you require.

Actually I usually try to cut pins on chips when I'm trying to isolate a
fault and don't want to cut the PCB (or veroboard) tracks. A bit of
component lead is soldered over the break after I'm satisfied. I have
managed it sometimes, but with great difficulty.

Cut tracks with a scalpel held at a sharp angle so the cut edges overlap.
flat it down after with the iron tip - it doesn't take much solder to
secure
the join.

I've tried a scalpel and often find I accidently jump over a few
tracks and leave a big slice over the board. Then I have to check
each of the other tracks to make sure I didn't accidently cut
through them, but usually I haven't because I usually have to
make multiple runs over a track with the scalpel to get all the
way through.

Use a Swan & Morton size 10 blade and stab with the point rather than slice
with the curved part.

If you need to carve - the blade is blunt.


---
This email has been checked for viruses by AVG.
http://www.avg.com

 

[Benderthe.evilrobot]

"keithr0" <user@account.invalid> wrote in message
news:ektmv7FpglmU1@mid.individual.net...

On 4/9/2017 3:19 AM, Benderthe.evilrobot wrote:

"keithr0" <user@account.invalid> wrote in message
news:ekr66uFab3pU1@mid.individual.net...
On 4/8/2017 8:17 AM, Clocky wrote:
On 8/04/2017 4:35 AM, Benderthe.evilrobot wrote:

"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:ekes48Frr3qU1@mid.individual.net...
https://www.jaycar.com.au/plastic-desolder-tool/p/TH1860

This is unsafe. It self-disassembles in use, projecting the handle
sharply upwards towards any vulnerable body part, with the eyes being
the most obvious targets.

Almost all the plastic body solder pumps I've had were crap.

Years ago I found a turned aluminium one in a tool box someone
dumped at
the recycling place.

Its pretty good - but I can't find any markings to identify the
manufacturer.

Does it look like this?

https://tronixstuff.files.wordpress.com/2012/09/suckersmall.jpg

I think I still have the one I bought from Tandy 30-odd years ago
somewhere, not that it was any good.


None of them are, the best method is solder wick, used properly it
will leave everything just as new. When I worked for NASA, it was the
only approved method of de-soldering.

Multilayer boards do heatsinking too well - solder wick can get stuck on
and make it too easy to pull tracks off.

Just learn how to do it properly, multi layer boards with power and ground
planes are difficult by any method.

But not difficult to damage with solder wick...........................


---
This email has been checked for viruses by AVG.
http://www.avg.com

 

[Computer Nerd Kev]

Benderthe.evilrobot <Benderthe.evilrobot@virginmedia.com> wrote:

"Computer Nerd Kev" <not@telling.you.invalid> wrote in message
newscbnng$1ao2$1@gioia.aioe.org...
Benderthe.evilrobot <Benderthe.evilrobot@virginmedia.com> wrote:

Cut tracks with a scalpel held at a sharp angle so the cut edges overlap.
flat it down after with the iron tip - it doesn't take much solder to
secure the join.

I've tried a scalpel and often find I accidently jump over a few
tracks and leave a big slice over the board. Then I have to check
each of the other tracks to make sure I didn't accidently cut
through them, but usually I haven't because I usually have to
make multiple runs over a track with the scalpel to get all the
way through.

Use a Swan & Morton size 10 blade and stab with the point rather than slice
with the curved part.

If you need to carve - the blade is blunt.

OK, I'll keep that in mind. Given the sort of nonsense I often get
up to with scalpels, blunt blades are quite a possibility.

--
__ __
#_ < |\| |< _#

 

[Trevor Wilson]

On 9/04/2017 7:14 PM, Phil Allison wrote:

Trevor Wilson wrote:


**They won't. If you think they do/will, then you need to get out a lot
more. Those old Hitachi MOSFETs, were very tough and ideally suited to
public address systems. For high quality audio, they suck.


** TW has been pushing this line of *complete bollocks* for decades.

He had a strong commercial motive - he sells expensive Hi-Fi
amplifiers ( ME brand) that used BJTs.


**You may care to note that I suggested a comparison with an old Phase
Linear amp.


** GAINT Yawnnnnnn .....

Wot a crock of context shifting BULLSHIT !!!!

**Well, no. Read my post. I CLEARLY AND UNEQUIVOCALLY suggested a
comparison between Perreaux and Phase Linear amps.

No mention of ME.


** It's all - me, me, me.

Dear Trev.



Having worked on some modern Perreaux amps,


** More context shifting CRAP.

TW is a charlatan, not a tech.



I am pleased to say that
they do not use the horrible old Hitachi MOSFETs and sound much better
than the old things.


** Just another of TW's insane thoughts presented as fact.

Just like all his AGW shite.

**What "AGW shite"? Be specific in your answer.



--
Trevor Wilson
www.rageaudio.com.au

 

[~misfit~]

Once upon a time on usenet Trevor Wilson wrote:

On 8/04/2017 10:51 PM, ~misfit~ wrote:
Once upon a time on usenet Phil Allison wrote:
Actually I usually try to cut pins on chips when I'm trying to
isolate a fault and don't want to cut the PCB (or veroboard)
tracks. A bit of component lead is soldered over the break after
I'm satisfied. I have managed it sometimes, but with great
difficulty.

That is a very crude method of fault finding, do you not own a
'scope and a good multimeter?


** Won't help if there is a short on a 5V DC supply rail with many
ICs and ceramic caps across it. Best way to find the culprit is to
use the "tune for maximum smoke" technique.

Apply a bench supply to the rail that has enough current to *smoke
out" out the cap or IC that is shorted.

Finds bad tantalums and ceramics in a couple of seconds, bad ICs may
be found with a finger test - AKA the "ouch" test.

Anyone who has serviced amplifiers using Hitachi TO3 mosfets in
parallel groups knows a finger test works to find any dead ones. Do
I need to explain?

FYI:

Hitachi TO3 mosfets have internal fuses that can isolate a bad
device during a short or other overload - the amp keeps working
albeit at somewhat reduced power capacity. Gotta love that.

Yep. I'm in the process of reconfiguring a pair of 100w mono amps
that are running two each J50 / K135 each to run on an extra +/- 15v
(and doubling the 2 x 10,000 uF of smoothing caps to 2 x 20,000 uF)
and paralleling a third pair of MOSFETs per amp (on small perfboard
daughterboards and fly leads), then building them both with their
power supplies into a big (re-purposed Perreaux PA amp) case and
adding a couple speaker protection modules.

They already sound really good with two pairs of devices each and
+/- 60v rails. They should sound awesome with three pairs and +/-
75v rails. <g

**They won't. If you think they do/will, then you need to get out a
lot more.

Fuck off with your insults. I read further down the thread and see you've
got commercial interests and good reason to insult me for your own profit.

As for reading this post further - no thanks.
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

Those old Hitachi MOSFETs, were very tough and ideally
suited to public address systems. For high quality audio, they suck.
Fundamentally, they are quite non-linear at anything under an Amp or
so of bias current. The negative tempco of gm means that any fast
rising transients and/or when using low impedance speakers will cause
a severe curtailing of dynamics.

I suggest you compare your MOSFET POS to an ancient Phase Linear 400
(or 700), or almost any other BJT amp. You will be stunned at how much
better the old PLs sound. Reliability, of course, is a different
matter. MOSFET amps tend to be very reliable, when properly designed.
As an example of very poor design, I refer you to the old and now
defunct, NRG (energy) brand of MOSFET amps. Extremely unstable
designs.

 

[~misfit~]

Once upon a time on usenet Phil Allison wrote:

Trevor Wilson wrote:


**They won't. If you think they do/will, then you need to get out
a lot more. Those old Hitachi MOSFETs, were very tough and ideally
suited to public address systems. For high quality audio, they
suck.


** TW has been pushing this line of *complete bollocks* for decades.

He had a strong commercial motive - he sells expensive Hi-Fi
amplifiers ( ME brand) that used BJTs.


**You may care to note that I suggested a comparison with an old
Phase Linear amp.


** GAINT Yawnnnnnn .....

Wot a crock of context shifting BULLSHIT !!!!



No mention of ME.


** It's all - me, me, me.

Dear Trev.



Having worked on some modern Perreaux amps,


** More context shifting CRAP.

TW is a charlatan, not a tech.

Yeah I get that. I'm not exactly cloth-eared and my MOSFET amplifiers sound
far better than anything else *I can afford*. They were originally made in
Auckland by an ex-employee of Perreaux in the 1980s. I have a couple 1970s
Perreaux band PA amps too and use the low channel of one for a subwoofer
amp. (I used to tour with a band doing stage lightning and soundmixing in
the 1970s.)

I am pleased to say that
they do not use the horrible old Hitachi MOSFETs and sound much
better than the old things.


** Just another of TW's insane thoughts presented as fact.

Just like all his AGW shite.

The narcissistic idiot thinks he thinks.

ROTFLMAO ....

Yeah, seems a stretch of the imagination.

**I serviced every single one of the tiny number of NRG amps that
made it to Australia. They all blew up. Several times. Worse, when
one channel went, I suspect some kind of oscillation was set up,
which took out the other channel. Every single MOSFET failed. I was
never able to ascertain why the amps failed, just that they did,
with monotonous regularity.

BTW: The MOSFETs were not Hitachi types.




** TW needs to visit a psychiatric hospital - for his own benefit.

And stay there, for our benefit.

Indeed. To insult me as a lead-in to his reply to me shows that he's not
good with people - unless he's just brave when he's behind a keyboard....
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

 

[Clocky]

On 10/04/2017 9:15 PM, ~misfit~ wrote:

Once upon a time on usenet Phil Allison wrote:
Trevor Wilson wrote:


**They won't. If you think they do/will, then you need to get out
a lot more. Those old Hitachi MOSFETs, were very tough and ideally
suited to public address systems. For high quality audio, they
suck.


** TW has been pushing this line of *complete bollocks* for decades.

He had a strong commercial motive - he sells expensive Hi-Fi
amplifiers ( ME brand) that used BJTs.


**You may care to note that I suggested a comparison with an old
Phase Linear amp.


** GAINT Yawnnnnnn .....

Wot a crock of context shifting BULLSHIT !!!!



No mention of ME.


** It's all - me, me, me.

Dear Trev.



Having worked on some modern Perreaux amps,


** More context shifting CRAP.

TW is a charlatan, not a tech.


Yeah I get that. I'm not exactly cloth-eared and my MOSFET amplifiers sound
far better than anything else *I can afford*. They were originally made in
Auckland by an ex-employee of Perreaux in the 1980s. I have a couple 1970s
Perreaux band PA amps too and use the low channel of one for a subwoofer
amp. (I used to tour with a band doing stage lightning and soundmixing in
the 1970s.)

I am pleased to say that
they do not use the horrible old Hitachi MOSFETs and sound much
better than the old things.


** Just another of TW's insane thoughts presented as fact.

Just like all his AGW shite.

The narcissistic idiot thinks he thinks.

ROTFLMAO ....


Yeah, seems a stretch of the imagination.

**I serviced every single one of the tiny number of NRG amps that
made it to Australia. They all blew up. Several times. Worse, when
one channel went, I suspect some kind of oscillation was set up,
which took out the other channel. Every single MOSFET failed. I was
never able to ascertain why the amps failed, just that they did,
with monotonous regularity.

BTW: The MOSFETs were not Hitachi types.




** TW needs to visit a psychiatric hospital - for his own benefit.

And stay there, for our benefit.

Indeed. To insult me as a lead-in to his reply to me shows that he's not
good with people - unless he's just brave when he's behind a keyboard....

I think he firmly believes in his own spin.

 

[Trevor Wilson]

On 10/04/2017 11:15 PM, ~misfit~ wrote:

Once upon a time on usenet Phil Allison wrote:
Trevor Wilson wrote:


**They won't. If you think they do/will, then you need to get out
a lot more. Those old Hitachi MOSFETs, were very tough and ideally
suited to public address systems. For high quality audio, they
suck.


** TW has been pushing this line of *complete bollocks* for decades.

He had a strong commercial motive - he sells expensive Hi-Fi
amplifiers ( ME brand) that used BJTs.


**You may care to note that I suggested a comparison with an old
Phase Linear amp.


** GAINT Yawnnnnnn .....

Wot a crock of context shifting BULLSHIT !!!!



No mention of ME.


** It's all - me, me, me.

Dear Trev.



Having worked on some modern Perreaux amps,


** More context shifting CRAP.

TW is a charlatan, not a tech.


Yeah I get that. I'm not exactly cloth-eared and my MOSFET amplifiers sound
far better than anything else *I can afford*.

**You think an old Phase Linear will be expensive? Really? They're cheap
and readily available.


They were originally made in

Auckland by an ex-employee of Perreaux in the 1980s. I have a couple 1970s
Perreaux band PA amps too and use the low channel of one for a subwoofer
amp. (I used to tour with a band doing stage lightning and soundmixing in
the 1970s.)

**Have you compared your MOSFET POS to an old Phase Linear?

I am pleased to say that
they do not use the horrible old Hitachi MOSFETs and sound much
better than the old things.


** Just another of TW's insane thoughts presented as fact.

Just like all his AGW shite.

The narcissistic idiot thinks he thinks.

ROTFLMAO ....


Yeah, seems a stretch of the imagination.

**I serviced every single one of the tiny number of NRG amps that
made it to Australia. They all blew up. Several times. Worse, when
one channel went, I suspect some kind of oscillation was set up,
which took out the other channel. Every single MOSFET failed. I was
never able to ascertain why the amps failed, just that they did,
with monotonous regularity.

BTW: The MOSFETs were not Hitachi types.




** TW needs to visit a psychiatric hospital - for his own benefit.

And stay there, for our benefit.

Indeed. To insult me as a lead-in to his reply to me shows that he's not
good with people - unless he's just brave when he's behind a keyboard....

**I did not insult you. I don't know you. I suggested that you compare
your MOSFET POS to an old Phase Linear. Those old Hitachi MOSFET amps
are crap. Modern MOSFET amps are MUCH better. As are old Phase Linear amps.

I did not make it personal. If you can find the words where I allegedly
insulted you, present them.


--
Trevor Wilson
www.rageaudio.com.au

 

[Trevor Wilson]

On 10/04/2017 11:08 PM, ~misfit~ wrote:

Once upon a time on usenet Trevor Wilson wrote:
On 8/04/2017 10:51 PM, ~misfit~ wrote:
Once upon a time on usenet Phil Allison wrote:
Actually I usually try to cut pins on chips when I'm trying to
isolate a fault and don't want to cut the PCB (or veroboard)
tracks. A bit of component lead is soldered over the break after
I'm satisfied. I have managed it sometimes, but with great
difficulty.

That is a very crude method of fault finding, do you not own a
'scope and a good multimeter?


** Won't help if there is a short on a 5V DC supply rail with many
ICs and ceramic caps across it. Best way to find the culprit is to
use the "tune for maximum smoke" technique.

Apply a bench supply to the rail that has enough current to *smoke
out" out the cap or IC that is shorted.

Finds bad tantalums and ceramics in a couple of seconds, bad ICs may
be found with a finger test - AKA the "ouch" test.

Anyone who has serviced amplifiers using Hitachi TO3 mosfets in
parallel groups knows a finger test works to find any dead ones. Do
I need to explain?

FYI:

Hitachi TO3 mosfets have internal fuses that can isolate a bad
device during a short or other overload - the amp keeps working
albeit at somewhat reduced power capacity. Gotta love that.

Yep. I'm in the process of reconfiguring a pair of 100w mono amps
that are running two each J50 / K135 each to run on an extra +/- 15v
(and doubling the 2 x 10,000 uF of smoothing caps to 2 x 20,000 uF)
and paralleling a third pair of MOSFETs per amp (on small perfboard
daughterboards and fly leads), then building them both with their
power supplies into a big (re-purposed Perreaux PA amp) case and
adding a couple speaker protection modules.

They already sound really good with two pairs of devices each and
+/- 60v rails. They should sound awesome with three pairs and +/-
75v rails. <g

**They won't. If you think they do/will, then you need to get out a
lot more.

Fuck off with your insults.

**What insults? Be precise in your answer.


I read further down the thread and see you've
> got commercial interests and good reason to insult me for your own profit.

**Bullshit. I have not sold a Phase Linear amp in years.

As for reading this post further - no thanks.

**Head, sand.

--
Trevor Wilson
www.rageaudio.com.au

 

[Trevor Wilson]

On 11/04/2017 1:16 AM, Clocky wrote:

On 10/04/2017 9:15 PM, ~misfit~ wrote:
Once upon a time on usenet Phil Allison wrote:
Trevor Wilson wrote:


**They won't. If you think they do/will, then you need to get out
a lot more. Those old Hitachi MOSFETs, were very tough and ideally
suited to public address systems. For high quality audio, they
suck.


** TW has been pushing this line of *complete bollocks* for decades.

He had a strong commercial motive - he sells expensive Hi-Fi
amplifiers ( ME brand) that used BJTs.


**You may care to note that I suggested a comparison with an old
Phase Linear amp.


** GAINT Yawnnnnnn .....

Wot a crock of context shifting BULLSHIT !!!!



No mention of ME.


** It's all - me, me, me.

Dear Trev.



Having worked on some modern Perreaux amps,


** More context shifting CRAP.

TW is a charlatan, not a tech.


Yeah I get that. I'm not exactly cloth-eared and my MOSFET amplifiers
sound
far better than anything else *I can afford*. They were originally
made in
Auckland by an ex-employee of Perreaux in the 1980s. I have a couple
1970s
Perreaux band PA amps too and use the low channel of one for a subwoofer
amp. (I used to tour with a band doing stage lightning and soundmixing in
the 1970s.)

I am pleased to say that
they do not use the horrible old Hitachi MOSFETs and sound much
better than the old things.


** Just another of TW's insane thoughts presented as fact.

Just like all his AGW shite.

The narcissistic idiot thinks he thinks.

ROTFLMAO ....


Yeah, seems a stretch of the imagination.

**I serviced every single one of the tiny number of NRG amps that
made it to Australia. They all blew up. Several times. Worse, when
one channel went, I suspect some kind of oscillation was set up,
which took out the other channel. Every single MOSFET failed. I was
never able to ascertain why the amps failed, just that they did,
with monotonous regularity.

BTW: The MOSFETs were not Hitachi types.




** TW needs to visit a psychiatric hospital - for his own benefit.

And stay there, for our benefit.

Indeed. To insult me as a lead-in to his reply to me shows that he's not
good with people - unless he's just brave when he's behind a keyboard....


I think he firmly believes in his own spin.

**Absolutely. An old Phase Linear will beat the pants off an old
Perreaux. Easily. Reliability is another matter, however.


--
Trevor Wilson
www.rageaudio.com.au

 

[Phil Allison]

~misfit~ wrote:

** More context shifting CRAP.

TW is a charlatan, not a tech.


Yeah I get that. I'm not exactly cloth-eared and my MOSFET amplifiers sound
far better than anything else *I can afford*. They were originally made in
Auckland by an ex-employee of Perreaux in the 1980s. I have a couple 1970s
Perreaux band PA amps too ..

** You just reminded me of the Perreaux BJT amplifier I saw and serviced in the early 80s - it was " P2200 " IIRC.

The design was reminiscent of a PL700, but with two large power transformers.
The transformers had their 120V primaries and 65V secondaries wired in series. The mid point of the secondaries went to ground and the ends to a bridge rectifier and pair of large filter electros.

Now, there is a *BIG* problem with this idea: in order for the DC voltages on the electros to match, the load current drawn from plus and minus supplies must match exactly - cos nothing forces the two transformers to share the 240 supply evenly.

As it was the DC rails were offset by 11 volts at idle, due to a 10kohm / 10W resistor on the positive side that fed a speaker relay.

On music programme, the rail offset varied about the 11 volt value.

The correct way is to have the secondaries wired in parallel, thereby forcing equal sharing of the AC supply voltage - but that could not be done in this case.

Peter Perreaux made no similar error with his MOSFET models, he got nearly everything near perfect, particularly with the heatsinking and fan cooling set up.

There was one oversight though, that caused a lot of grief for owners about 5 or 10 years later. Anyone here know what it was ?


..... Phil

 

[~misfit~]

Once upon a time on usenet Clocky wrote:

On 10/04/2017 9:15 PM, ~misfit~ wrote:
Once upon a time on usenet Phil Allison wrote:
Trevor Wilson wrote:


**They won't. If you think they do/will, then you need to get out
a lot more. Those old Hitachi MOSFETs, were very tough and
ideally suited to public address systems. For high quality
audio, they suck.


** TW has been pushing this line of *complete bollocks* for
decades. He had a strong commercial motive - he sells expensive Hi-Fi
amplifiers ( ME brand) that used BJTs.


**You may care to note that I suggested a comparison with an old
Phase Linear amp.


** GAINT Yawnnnnnn .....

Wot a crock of context shifting BULLSHIT !!!!



No mention of ME.


** It's all - me, me, me.

Dear Trev.



Having worked on some modern Perreaux amps,


** More context shifting CRAP.

TW is a charlatan, not a tech.


Yeah I get that. I'm not exactly cloth-eared and my MOSFET
amplifiers sound far better than anything else *I can afford*. They
were originally made in Auckland by an ex-employee of Perreaux in
the 1980s. I have a couple 1970s Perreaux band PA amps too and use
the low channel of one for a subwoofer amp. (I used to tour with a
band doing stage lightning and soundmixing in the 1970s.)

I am pleased to say that
they do not use the horrible old Hitachi MOSFETs and sound much
better than the old things.


** Just another of TW's insane thoughts presented as fact.

Just like all his AGW shite.

The narcissistic idiot thinks he thinks.

ROTFLMAO ....


Yeah, seems a stretch of the imagination.

**I serviced every single one of the tiny number of NRG amps that
made it to Australia. They all blew up. Several times. Worse, when
one channel went, I suspect some kind of oscillation was set up,
which took out the other channel. Every single MOSFET failed. I was
never able to ascertain why the amps failed, just that they did,
with monotonous regularity.

BTW: The MOSFETs were not Hitachi types.




** TW needs to visit a psychiatric hospital - for his own benefit.

And stay there, for our benefit.

Indeed. To insult me as a lead-in to his reply to me shows that he's
not good with people - unless he's just brave when he's behind a
keyboard....

I think he firmly believes in his own spin.

Ok, thanks.

That's the worst kind of religious nutcase. (Think Jonestown...)

Cheers,
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

 

[Trevor Wilson]

On 11/04/2017 11:15 AM, ~misfit~ wrote:

Once upon a time on usenet Clocky wrote:
On 10/04/2017 9:15 PM, ~misfit~ wrote:
Once upon a time on usenet Phil Allison wrote:
Trevor Wilson wrote:


**They won't. If you think they do/will, then you need to get out
a lot more. Those old Hitachi MOSFETs, were very tough and
ideally suited to public address systems. For high quality
audio, they suck.


** TW has been pushing this line of *complete bollocks* for
decades. He had a strong commercial motive - he sells expensive Hi-Fi
amplifiers ( ME brand) that used BJTs.


**You may care to note that I suggested a comparison with an old
Phase Linear amp.


** GAINT Yawnnnnnn .....

Wot a crock of context shifting BULLSHIT !!!!



No mention of ME.


** It's all - me, me, me.

Dear Trev.



Having worked on some modern Perreaux amps,


** More context shifting CRAP.

TW is a charlatan, not a tech.


Yeah I get that. I'm not exactly cloth-eared and my MOSFET
amplifiers sound far better than anything else *I can afford*. They
were originally made in Auckland by an ex-employee of Perreaux in
the 1980s. I have a couple 1970s Perreaux band PA amps too and use
the low channel of one for a subwoofer amp. (I used to tour with a
band doing stage lightning and soundmixing in the 1970s.)

I am pleased to say that
they do not use the horrible old Hitachi MOSFETs and sound much
better than the old things.


** Just another of TW's insane thoughts presented as fact.

Just like all his AGW shite.

The narcissistic idiot thinks he thinks.

ROTFLMAO ....


Yeah, seems a stretch of the imagination.

**I serviced every single one of the tiny number of NRG amps that
made it to Australia. They all blew up. Several times. Worse, when
one channel went, I suspect some kind of oscillation was set up,
which took out the other channel. Every single MOSFET failed. I was
never able to ascertain why the amps failed, just that they did,
with monotonous regularity.

BTW: The MOSFETs were not Hitachi types.




** TW needs to visit a psychiatric hospital - for his own benefit.

And stay there, for our benefit.

Indeed. To insult me as a lead-in to his reply to me shows that he's
not good with people - unless he's just brave when he's behind a
keyboard....

I think he firmly believes in his own spin.

Ok, thanks.

That's the worst kind of religious nutcase. (Think Jonestown...)

**Back when Perreaux released the 2150b power amp, everyone fell over
themselves saying wonderful things about the amp. Curious, I arranged to
listen to one. I was unimpressed. I then decided to compare the 2150b
with several different amplifiers. One was a Phase Linear 400 Series
Two. It was an astonishing thing. The old Phase Linear (it was about 7-8
years old at the time) sounded MUCH better than the Perreaux. By a very
considerable margin. Subsequently, I listened to lots of other Perreaux
amps. They are had the same, boring sonic character. Even the massive
5150b. Lots of power, no finesse and severely curtailed dynamics.
Particularly when used with ESLs. Perreaux and Quads is a particularly
bad match.


I suggest that you do what I did: LISTEN for yourself. Make up your own
mind.

Or, you could just stick your head in the sand and pretend that I don't
know what I am talking about.


Remember this: I am just suggesting that you should LISTEN for yourself.
Nothing more.

I should add that I have noted YOUR insults and also that you have
failed to demonstrate where I (allegedly) insulted you. Explaining that
an old Perreaux amp is a POS is not an insult. It is a fact.

--
Trevor Wilson
www.rageaudio.com.au

 

[Trevor Wilson]

On 11/04/2017 3:10 PM, Phil Allison wrote:

~misfit~ wrote:



** More context shifting CRAP.

TW is a charlatan, not a tech.


Yeah I get that. I'm not exactly cloth-eared and my MOSFET
amplifiers sound far better than anything else *I can afford*. They
were originally made in Auckland by an ex-employee of Perreaux in
the 1980s. I have a couple 1970s Perreaux band PA amps too ..


** You just reminded me of the Perreaux BJT amplifier I saw and
serviced in the early 80s - it was " P2200 " IIRC.

The design was reminiscent of a PL700, but with two large power
transformers. The transformers had their 120V primaries and 65V
secondaries wired in series. The mid point of the secondaries went to
ground and the ends to a bridge rectifier and pair of large filter
electros.

Now, there is a *BIG* problem with this idea: in order for the DC
voltages on the electros to match, the load current drawn from plus
and minus supplies must match exactly - cos nothing forces the two
transformers to share the 240 supply evenly.

As it was the DC rails were offset by 11 volts at idle, due to a
10kohm / 10W resistor on the positive side that fed a speaker relay.

On music programme, the rail offset varied about the 11 volt value.

The correct way is to have the secondaries wired in parallel, thereby
forcing equal sharing of the AC supply voltage - but that could not
be done in this case.

Peter Perreaux made no similar error with his MOSFET models, he got
nearly everything near perfect, particularly with the heatsinking and
fan cooling set up.

There was one oversight though, that caused a lot of grief for owners
about 5 or 10 years later. Anyone here know what it was ?

**Power switch failures? Dry solder joints on the driver devices, due to
constant high temperature operation? Fuse holder failures?

I haven't seen many of their pro amps, but their domestic amps suffer
these problems after a few years. That said, they are generally quite
reliable (but crap sounding). The Phase Linears were the opposite.
Better sounding, but less reliable.


--
Trevor Wilson
www.rageaudio.com.au

 

[Phil Allison]

Trevor Wilson wrote:

Peter Perreaux made no similar error with his MOSFET models, he got
nearly everything near perfect, particularly with the heatsinking and
fan cooling set up.

There was one oversight though, that caused a lot of grief for owners
about 5 or 10 years later. Anyone here know what it was ?


**Power switch failures?

** Yeah, seen a few of them.

Managed get a stock of the correct ones from a McMurdo dealer.

Dry solder joints on the driver devices, due to
constant high temperature operation? Fuse holder failures?

** No.

This problem was related to the use of internal fan cooling and affected all models from the PMF2000 onwards to the PMF9000.



...... Phil