On 14 Jun 2004 07:54:45 GMT, ohawker (Andy
Evans) wrote:

The moral of this tale is that if you want to make sure nobody can disagree
with you, just say stuff that is devoid of any meaning.

OK, Don. you are by your own admission a consultant and this is a thread about
valve amplifiers. What I propose is that you give me a selection of your own
valve amplifier circuit designs with your detailed construction notes which
prove that substituting componants has no effect on the sound. In return I will
give you a selection of my own valve amplifier circuit designs with my detailed
construction notes on the diverse effects of substituting componants. You are
welcome to breadboard my circuits with the relevant parts to check whether your
own ears confirm the effects I have found. That sounds reasonable doesn't it?
Let's put this to the test.

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

Are you telling me that your designs are so incompetent that the
resulting sound changes with - as I have offered - the degree of
warmup, ageing etc of the valves? If your designs really do sound
different depending on what kind of resistors etc you use, then please
go and find a new career. You aren't up to this one.

d
Pearce Consulting
http://www.pearce.uk.com

On Mon, 14 Jun 2004 08:43:02 +0100, Jim Lesurf
wrote:

In article , Keith G
wrote:

"Jim Lesurf" wrote in message
...


The performance of an amplifier comes from the way all the components
work in conjunction. Just replacing one item with a 'better' one might
simply make the performance worse...


Indeed, 'upset the balance', as it were. In which case one would need to
reverse the changes or move onto different components, which I guess is
pretty much how valve amplifier designs are finalised anyway.

There is a state in the process of devolpment and design which I tend to
call 'lost in space'. :-)

This is where you have a number of variables (choice of component types,
choice of values, slight topology changes, etc) and want to 'optimise' a
design. Since they all tend to interact, if you just try changing one thing
or another you can end up 'wandering about' in terms of the state of the
unit. With luck (and time!) you can end up in a place which seems OK.
However you may then have no real idea *why*. Nor know that a better result
might be nearby, but you never wandered past it...

I must admit that a lot of what I've read about the process of people
trying 'different' components to see what they does sound a bit like the
above to me.

Part of the appeal of valve kit to some people is that it can be
'tweaked' in a comparatively easy way, making the amplifier a more
significant contributor to the overall sound characteristics of a
'hi-fi' system. Not that everybody thinks that is necessarily a good
thing - I've been so pleased with the sound I get using my own kit amp,
I've never been tempted to fiddle with it......

My worries about the above a

1) The 'lost in space' problem. Might be a 'better' arrangement that could
have been cheaper and easier if you'd known.

2) People then not knowing that the resulting amp is unstable or marginal,
or has a reduced life or safety margin. (I am particularly worried about
this when a design is developed for kit use as the original development may
then not have covered properly the effects of normal component variations.
I recall WW kit designs being called 'Worked Wunce' rather than 'Wireless
World' by some professionals. :-) )

For the above reasons my own inclination is to treat the system as a whole
and do relevant measurements as well as listen. However I am unsure how
many DIY or kit builders do this.

Slainte,

Jim

This problem is particularly to be found in the "high end", where
there is simply not enough time and money to develop a design
properly, which generally takes a large number of models to establish
- as you imply - criteria for tolerance sensitivity, stability etc.
The result is that every unit sold is essentially an under-designed,
under-tested prototype, which really should never have left the
premises.

A properly-engineered design simply never gets the chance to happen in
this market, whereas further down the food chain, not only can it
happen, but it absolutely MUST happen, or heads start rolling.

d
Pearce Consulting
http://www.pearce.uk.com

My vote tends to go for *informed* choice. Hence I'd like people to try and
understand the physical and engineering reasons why there may be differences

I completely agree. I'm sure you know by now that I hold engineering in the
highest regard. I doubt whether this is practical, however, and this raises a
whole other raft of questions about what we are measuring etc etc. There are
times when it is just a case of 'I prefer A to B' and I don't think that is
intrinsically wrong. If I had the equipment and knowledge and time I'd love to
measure things, but I'm an amateur builder and have limited time to spare. I
am, however, a professional musician and I do know exactly what I'm listening
for, so that's some help.

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

The result is that every (high end) unit sold is essentially an under-designed,
under-tested prototype, which really should never have left the premises.


You do say the most incredible things. Tell that to Victor Khomenko or Lynn
Olsen for instance

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

Afraid I'm not a 'physicist' any more. I retired last month...

Happy retirement, Jim! Or is another career beckoning...........

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

There is a state in the process of devolpment and design which I tend to
call 'lost in space'. :-) This is where you have a number of variables and
want to 'optimise' a design. Since they all tend to interact, you may then have
no real idea *why*. Nor know that a better result
might be nearby, but you never wandered past it...

I think that's a very succinct way of putting it, and I'd be surprised if most
amp developers haven't gone through this stage. Mind, some of us enjoy being
lost in space.....

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

Are you telling me that your designs are so incompetent that (blah blah).

I repeat exactly what I said before. Give me a selection of valve circuits that
you have personally designed, with detailed construction notes showing that
changing componants had no effect on he sound.

See below:
What I propose is that you give me a selection of your own valve amplifier
circuit designs with your detailed construction notes which prove that
substituting componants has no effect on the sound. In return I will give you a
selection of my own valve amplifier circuit designs with my detailed
construction notes on the diverse effects of substituting componants. You are
welcome to breadboard my circuits with the relevant parts to check whether your
own ears confirm the effects I have found. That sounds reasonable doesn't it?
Let's put this to the test.







=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

"Jim Lesurf" wrote in message
...
In article , Trevor Wilson
wrote:


**Ah, The Prisoner. Now THAT was a great TV show. Along with The
Avengers, it was the pinnacle of Pommy TV (thinks of Mrs Peel and that
Lotus).

Now being rebroadcast on Friday nights on BBCTV4. :-)

Pleased I now have a DVD recorder... :-)

I did buy some of the 'Avengers' DVDs, but they went out of print before I
could get them all. Agree with you that these are excellent.


**We must talk. -

Did you manage to get any of the later series, with Purdy and Gambit? (Mmmm,
thinks of Purdy lustfully)


--
Trevor Wilson
www.rageaudio.com.au

"Jim Lesurf" wrote in message
...
In article , Don Pearce
wrote:


Add to this, of course the basic inconsistency here of the very idea of
"voicing" an amplifier. An amplifier should not have a voice. It should
be totally self-effacing. Anything less simply gets in the way of the
music. Of course you may actually be into sound effects - in which case
ignore me and go right ahead.

I suppose this is a matter of preference.

It is my suspicion that some people prefer, for example, the changes in
overall frequency response that may arise due to am amp having a
(relatively) high output impedance. Thus in part using something like a
low-feedback design as an expensive 'tonal adjuster'. If they like that,
it
is fine with me.

My own preference, though, tends to be for amplifiers which just 'get out
of the way' and leave me to hear the actual recorded/broadcast sounds.
Hence I don't want a 'voiced' amplifier, I want to hear the music, not the
amplifier.

Cue discussion of the meaning of "fidelity"... :-)

**More wise words, Jim. I have actually submitted myself to several blind
tests, between several amplifiers (SS and valve). In many ways, the results
were quite humbling. Mostly because in one test, I was unable to pick the
difference between an expensive valve amp and an expensive SS amp. Cheap
valve amps (and all SET) were VERY easy to pick. ALL valve amps are easy yo
pick, if the load impedance is sufficiently brutal. Ditto with SS amps,
which have inadequate current limiting, of course.

I have a friend who owned a very high quality SS amp, but desired to
experiment with valve amps. He purchased a reasonably good valve amp and did
some comparisons. He found that the valve amp sounded quite different to the
SS amp. He then embarked upon a year long project to improve the valve amp.
His first task was to replace coupling caps and resistors with higher
quality devices. Next was to make the power supply stiffer. Then he had
custom output transformers wound with 13 interleaves. After all that work he
had an amplifier which sounded much more like his SS unit. At about 3 times
the price..........


--
Trevor Wilson
www.rageaudio.com.au

"Don Pearce" wrote in message
...
On Mon, 14 Jun 2004 08:43:02 +0100, Jim Lesurf


This problem is particularly to be found in the "high end", where
there is simply not enough time and money to develop a design
properly, which generally takes a large number of models to establish
- as you imply - criteria for tolerance sensitivity, stability etc.
The result is that every unit sold is essentially an under-designed,
under-tested prototype, which really should never have left the
premises.

**Nonsense. High end designs can be very mature, depending on the talent of
the designer and his manufacturing team. SOME designs are as you say they
are, however.


A properly-engineered design simply never gets the chance to happen in
this market, whereas further down the food chain, not only can it
happen, but it absolutely MUST happen, or heads start rolling.

**Utter and complete ********. In a past life, I was service manager of
Marantz (Australia). Each month I received a flood of modification sheets
for many Marantz models. These ranged from relatively minor stuff, to major
mods to various products. One of those products concerned an amplifier which
I still own. The Marantz Model 500 power amp. An impressive beast, of (then)
prodigious power output. The 500 was stunningly unreliable, mostly due to
the use of complementary symmetry output devices, at a time when such
devices were both unreliable and of marginal ratings. 300 amps were
manufactured by Marantz USA. They had an RRP of AUS$1,500.00 in 1974. Three
units were imported into Australia and each amp (with the exception of mine)
had to be serviced around 5-6 times, before head office figured out how to
prevent them from self-destructing every few weeks. Each repair took around
10-12 hours. Rumour has it that the entire Model 500 project cost Superscope
inc (Marantz's owners) US$3 million, from cradle to grave (initial design,
to the end of the warranty period). It almost sent them to the wall.

Along with mod sheets, I also had access to a fascinating document, which
outlined the reliability figures of every Marantz model (for the duration of
the 3 year warranty period). The legendary Model 1070 enjoyed a failure rate
of 0.5%, whilst the 4230 enjoyed a failure rate of 60%. The Model 500
enjoyed a failure rate of 100%.

I am presently a service agent for a number of large, well known brands.
Whilst chatting to the service manager of one of these brands, he casually
mentioned that their then current DVD player enjoyed a 63% failure rate. And
this was in 2003, not 1973!

Make no mistake: MANY designs are being produced which are incomplete
designs. It will always be that way, it seems.


--
Trevor Wilson
www.rageaudio.com.au