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

**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.

I'd also like to see the details of the circuits, methodology, and results.

I've often in the past compared amps made with MOSFETs with BJT. So far as
I could tell they were audibly indistinguishable provided you avoided
errors like trying to obtain power or current levels which a design could
not provide. And so far as I recall, all the published controlled tests
also show this. Certainly all the ones I've seen.

So where are the details of your DBT Trevor?

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

On Wed, 4 Nov 2009 08:47:13 +1100, "Trevor Wilson"
wrote:

We're discussing compression, which can be measured objectively -
please don't try to divert the discussion onto the metaphysical. Show
me compression.

**DBTs are not metaphysical. They allow REAL differences to be heard. Tell
me about your experiences with DBTs between MOSFET and BJT amps.


Stop changing the subject. Either there is compression as you claim,
or there is not. Show me evidence of compression.

d

"Don Pearce" wrote in message
...
On Wed, 4 Nov 2009 08:47:13 +1100, "Trevor Wilson"
wrote:

We're discussing compression, which can be measured objectively -
please don't try to divert the discussion onto the metaphysical. Show
me compression.

**DBTs are not metaphysical. They allow REAL differences to be heard. Tell
me about your experiences with DBTs between MOSFET and BJT amps.


Stop changing the subject. Either there is compression as you claim,
or there is not. Show me evidence of compression.

**I cannot. Try the test and let me know what you hear. Perhaps you will
have a different explanation. Negative tempco of gm is the only thing that
makes sense to me.


--
Trevor Wilson
www.rageaudio.com.au

On Wed, 4 Nov 2009 09:12:59 +1100, "Trevor Wilson"
wrote:


"Don Pearce" wrote in message
...
On Wed, 4 Nov 2009 08:47:13 +1100, "Trevor Wilson"
wrote:

We're discussing compression, which can be measured objectively -
please don't try to divert the discussion onto the metaphysical. Show
me compression.

**DBTs are not metaphysical. They allow REAL differences to be heard. Tell
me about your experiences with DBTs between MOSFET and BJT amps.


Stop changing the subject. Either there is compression as you claim,
or there is not. Show me evidence of compression.

**I cannot. Try the test and let me know what you hear. Perhaps you will
have a different explanation. Negative tempco of gm is the only thing that
makes sense to me.

We are discussing one single parameter - compression. Once you start
with nonsense like seeing what you hear, you are no longer able to
isolate that parameter - you hear the sum of everything. And of course
mixed in with your "just listen" thing is all your bull****tery with
terms like "more dynamic". This is meaningless drivel, and the
standard recourse of the charlatan trying to claim superior skills of
discernment to the average man. It won't wash. You made the claim, now
substantiate it or withdraw it.

d

"Don Pearce" wrote in message
...
On Wed, 4 Nov 2009 09:12:59 +1100, "Trevor Wilson"
wrote:


"Don Pearce" wrote in message
...
On Wed, 4 Nov 2009 08:47:13 +1100, "Trevor Wilson"
wrote:

We're discussing compression, which can be measured objectively -
please don't try to divert the discussion onto the metaphysical. Show
me compression.

**DBTs are not metaphysical. They allow REAL differences to be heard.
Tell
me about your experiences with DBTs between MOSFET and BJT amps.


Stop changing the subject. Either there is compression as you claim,
or there is not. Show me evidence of compression.

**I cannot. Try the test and let me know what you hear. Perhaps you will
have a different explanation. Negative tempco of gm is the only thing that
makes sense to me.

We are discussing one single parameter - compression. Once you start
with nonsense like seeing what you hear, you are no longer able to
isolate that parameter - you hear the sum of everything. And of course
mixed in with your "just listen" thing is all your bull****tery with
terms like "more dynamic". This is meaningless drivel, and the
standard recourse of the charlatan trying to claim superior skills of
discernment to the average man. It won't wash. You made the claim, now
substantiate it or withdraw it.

**I'm uncertain of what you are demanding I withdraw. Are you demanding that
I withdraw my theory that pertains to why MOSFET amps sound so bad? Or are
you demanding I withdraw what I and others hear?

Given the problems that many people hear with MOSFET amps, I proferred a
theory. I cannot validate that theory. If you have an alternate theory to
explain what people hear, then please present it.

As for claims of "superior skills of discernment", I make no such claims. My
hearing is just average. Anyone with average hearing will easily discern the
problems I speak of. I suggest you conduct your own test and confirm.
Perhaps you will develop a more credible theory.


--
Trevor Wilson
www.rageaudio.com.au

On Wed, 4 Nov 2009 10:27:39 +1100, "Trevor Wilson"
wrote:


"Don Pearce" wrote in message
...
On Wed, 4 Nov 2009 09:12:59 +1100, "Trevor Wilson"
wrote:


"Don Pearce" wrote in message
...
On Wed, 4 Nov 2009 08:47:13 +1100, "Trevor Wilson"
wrote:

We're discussing compression, which can be measured objectively -
please don't try to divert the discussion onto the metaphysical. Show
me compression.

**DBTs are not metaphysical. They allow REAL differences to be heard.
Tell
me about your experiences with DBTs between MOSFET and BJT amps.


Stop changing the subject. Either there is compression as you claim,
or there is not. Show me evidence of compression.

**I cannot. Try the test and let me know what you hear. Perhaps you will
have a different explanation. Negative tempco of gm is the only thing that
makes sense to me.

We are discussing one single parameter - compression. Once you start
with nonsense like seeing what you hear, you are no longer able to
isolate that parameter - you hear the sum of everything. And of course
mixed in with your "just listen" thing is all your bull****tery with
terms like "more dynamic". This is meaningless drivel, and the
standard recourse of the charlatan trying to claim superior skills of
discernment to the average man. It won't wash. You made the claim, now
substantiate it or withdraw it.

**I'm uncertain of what you are demanding I withdraw. Are you demanding that
I withdraw my theory that pertains to why MOSFET amps sound so bad? Or are
you demanding I withdraw what I and others hear?


The one specific claim which is the ONLY one I have been discussing in
the face of your attempts to drag the conversation into the nebulous -
compression by MOSFET amplifiers.

irrelevant stuff snipped

d