"David Looser" wrote in
message
"Trevor Wilson" wrote

**DBTs are not metaphysical. They allow REAL differences
to be heard. Tell me about your experiences with DBTs
between MOSFET and BJT amps.
I'd be interested to know how these DBTs were conducted.
How many listeners did you use?, how were they recruited,
how much did they know about the purpose of the test? etc.

In the end you've got to go to Australia to see Trevor prove his point. I've
been down this road with him before in his anti-loop-feedback days.

"Arny Krueger" wrote in message
...
"David Looser" wrote in
message
"Trevor Wilson" wrote

**DBTs are not metaphysical. They allow REAL differences
to be heard. Tell me about your experiences with DBTs
between MOSFET and BJT amps.
I'd be interested to know how these DBTs were conducted.
How many listeners did you use?, how were they recruited,
how much did they know about the purpose of the test? etc.

In the end you've got to go to Australia to see Trevor prove his point.
I've been down this road with him before in his anti-loop-feedback days.

**Perhaps you missed my last post to you.

Here it is:

---
**I'll make it easy for you. Locate an old Phase Linear 400(b) and an early
Perreaux amp. Set up a DBT between the two and ask the listeners what
differences they feel they can hear (if any). Let me know what results you
find. Both amps are plentiful and cheap, so the test should be an easy one.
Both amps use ****-loads of global NFB, minimal bias current and primitive
topology so the only major differences are related to the output devices
used.

Take the time to listen for yourself. You might be surprised. I was.
---

Both amps were readily available in the US (and other places) and should be
very cheap and easy to obtain. No need to travel to Australia.

--
Trevor Wilson
www.rageaudio.com.au

In article , Trevor Wilson
wrote:

--- **I'll make it easy for you. Locate an old Phase Linear 400(b) and
an early Perreaux amp.

Your definition of "easy" seems to differ from mine. I do have new
neighbours moving in today though. Maybe they'll have the above amps to
loan me. :-)

Set up a DBT between the two and ask the listeners what differences they
feel they can hear (if any). Let me know what results you find. Both
amps are plentiful and cheap, so the test should be an easy one. Both
amps use ****-loads of global NFB, minimal bias current and primitive
topology so the only major differences are related to the output devices
used.

My problem here is that in the past I *have* repeately compared amps with
different types of op devices. And heard no differences due to that when
the amps were used within their drive limits and had much the same
frequency response, etc. i.e. were sensible designs.

In addition all the properly controlled blind comparisons I've seen
published results from that could be analysed return the same result.

So if your tests show otherwise it would be important to have all the
details published for examination and consideration.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

"Trevor Wilson" wrote in
message
"Arny Krueger" wrote in message
...
"David Looser" wrote in
message
"Trevor Wilson" wrote

**DBTs are not metaphysical. They allow REAL
differences to be heard. Tell me about your
experiences with DBTs between MOSFET and BJT amps.
I'd be interested to know how these DBTs were conducted.
How many listeners did you use?, how were they
recruited, how much did they know about the purpose of
the test? etc.

In the end you've got to go to Australia to see Trevor
prove his point. I've been down this road with him
before in his anti-loop-feedback days.

**Perhaps you missed my last post to you.

Not at all.

Your suggest is actually less practical than me catching the next flight to
down under.

(True! read below!)

Here it is:

---
**I'll make it easy for you. Locate an old Phase Linear
400(b)

I don't have any, and don't know anybody who currently has one.

If I wanted to buy one, they seem to be going for about $500 on eBay.

and an early Perreaux amp.

I don't have any, and don't know anybody who even ever had one.

I don't even know what the model number would be, since you are so vague in
describing it.

I see that I could pick a fairly decent Perreaux amp up for $1,500 on eBay.

Northwest airlines will sell me a round trip ticket from DTW to SYD for
$1,295.

I have proven that your suggestion is even less practical than what I first
suggested.


Set up a DBT between
the two and ask the listeners what differences they feel
they can hear (if any). Let me know what results you
find. Both amps are plentiful and cheap, so the test
should be an easy one. Both amps use ****-loads of global
NFB, minimal bias current and primitive topology so the
only major differences are related to the output devices
used.


The real truth Trevor is that if all amplifiers sounded as different as you
claim, there would be a world of amps that would DBT different, not just an
early SS old-timer well-known for being a loser (whether true or not) and
some esoteric wunder-amp.

"Arny Krueger" wrote in message
...
"Trevor Wilson" wrote in
message
"Arny Krueger" wrote in message
...
"David Looser" wrote in
message
"Trevor Wilson" wrote

**DBTs are not metaphysical. They allow REAL
differences to be heard. Tell me about your
experiences with DBTs between MOSFET and BJT amps.
I'd be interested to know how these DBTs were conducted.
How many listeners did you use?, how were they
recruited, how much did they know about the purpose of
the test? etc.

In the end you've got to go to Australia to see Trevor
prove his point. I've been down this road with him
before in his anti-loop-feedback days.

**Perhaps you missed my last post to you.

Not at all.

Your suggest is actually less practical than me catching the next flight
to down under.

(True! read below!)

Here it is:

---
**I'll make it easy for you. Locate an old Phase Linear
400(b)

I don't have any, and don't know anybody who currently has one.

If I wanted to buy one, they seem to be going for about $500 on eBay.

**Sorry. It's as easy as I can make it. Old Phase Linear amps are very
common over here. I'd assumed they'd be just as common in the US.


and an early Perreaux amp.

I don't have any, and don't know anybody who even ever had one.

I don't even know what the model number would be, since you are so vague
in describing it.

**Model 2150.


I see that I could pick a fairly decent Perreaux amp up for $1,500 on
eBay.

**Given that it is a crap amp, but reliable, colour me surprised that they
sell for so much.


Northwest airlines will sell me a round trip ticket from DTW to SYD for
$1,295.

I have proven that your suggestion is even less practical than what I
first suggested.

**Only for you. I provided a most economical solution.



Set up a DBT between
the two and ask the listeners what differences they feel
they can hear (if any). Let me know what results you
find. Both amps are plentiful and cheap, so the test
should be an easy one. Both amps use ****-loads of global
NFB, minimal bias current and primitive topology so the
only major differences are related to the output devices
used.


The real truth Trevor is that if all amplifiers sounded as different as
you claim

**BZZZTTT! I claimed nothing of the sort. I claimed that the Phase Linear
400(b) sounds different to a Perreaux 2150.

, there would be a world of amps that would DBT different, not just an
early SS old-timer well-known for being a loser (whether true or not) and
some esoteric wunder-amp.

**We're discussing Phase Linear and Perreaux amps from the late 1970s and
early 1980s.


--
Trevor Wilson
www.rageaudio.com.au

"Trevor Wilson" wrote

**We're discussing Phase Linear and Perreaux amps from the late 1970s and
early 1980s.


OK, good. So this is nothing to do with MOSFETS in general, merely one
particular rather ancient amplifier. Glad we got that clarified.

David.

In article , David Looser
wrote:
"Trevor Wilson" wrote

**We're discussing Phase Linear and Perreaux amps from the late 1970s
and early 1980s.


OK, good. So this is nothing to do with MOSFETS in general, merely one
particular rather ancient amplifier. Glad we got that clarified.

Yes. If that is the case then it makes more sense to me since I have also
encountered some amps that 'sounded different' because they had some flaw
or limitation in the design. Given some of the weirder designs that are
sold to 'audiophiles' I find it quite plausible. But it may tell us nothing
about MOSFET vs Bipolar as classes when used appropriately within their
limits.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

"Jim Lesurf" wrote in message

In article , David
Looser wrote:
"Trevor Wilson" wrote

**We're discussing Phase Linear and Perreaux amps from
the late 1970s and early 1980s.

OK, good. So this is nothing to do with MOSFETS in
general, merely one particular rather ancient amplifier.
Glad we got that clarified.

IOW, it is essentially OT to the OP and most of the discussion that followed
it.

Yes. If that is the case then it makes more sense to me
since I have also encountered some amps that 'sounded
different' because they had some flaw or limitation in
the design.

However, there's no reliable evidence that the amps that Trevor mentioned
have this kind of flaw.

So Trevor's proposed test is doubly irrelevant. It's not about the kind of
amps that this thread was created to discuss, and there's no reliable
evidence that the amps he mentioned actually have audible design flaws as
typically used.

Given some of the weirder designs that are
sold to 'audiophiles' I find it quite plausible.

Aside from that, there is a lot of audiophile lore and legend about certain
amps always sounding bad, when said amps in good operating condition
actually sound OK. Any amp that was sold in large volumes and may have been
prone to failure might be getting this kind of treatment. This is especially
true if the amp has a common failure mode that does not completely disable
it.

But it
may tell us nothing about MOSFET vs Bipolar as classes
when used appropriately within their limits.

Exactly. My audio club has examined this issue in some depth and no
surprise, we found that a properly-designed amp in good operating condition
sounds great, no matter which type of output device is used.

There is a precident for this. There was a class of SS output device that
was widely used and has completely fallen into complete disuse. But, that
did not happen to either MOSFET or Bipolar technology. I suspect that if
marketing stats were avaialble we'd find that there was a time when MOSFET
usage increased dramatically and obtained a fair market share. Since then,
MOSFET use has probably decreased, but there is still significant use of it.

The engineers I talk to say that linear (not switchmode) MOSFET amps tend to
be more costly and less efficient for a given power and performance level.
Note that a long-time advocate of FET power amps for audio, namely Hafler is
no longer in production. Haflers had a reputation for sounding great but
being costly and inefficient. Not all that inefficient, but audio can be a
very competitive business.