"Arny Krueger"


There are many reasons to mod power amps. For amps of the 405 vintage
output devices with gobs more SOA might make some sense for the sake of
durability.

** Quad used the best they could find at the time.

Quads "current dumping" topology allowed the use of "slow" output devices
and that corresponded with large chips and lots of safe operating area. The
original 405 use BDY77s, the 405-2 used Toshiba 2SD424s and later examples
used Motorola MJ15003s.


Most capacitor upgrade mods are ******** at face value but an amp of 405
vintage could have a fair number of dried out electrolytics.

** Repairs and restorations are not "mods".


Most mods are done by audio illiterates who have no or very limited test
equipment and wouldn't know how to do a good power amp listening test if
they ever wanted to. Letsee, I saw a 'scope and implications of a
voltmeter in the mods. Did I miss a THD analyzer hidden in the wings? ;-)


** The THD residual of a 405 (under load) comes entirely from the power
output stage, the op-amp preamp is not involved as there is no loop feedback
around it at audio frequencies.

Hence most audiophool mods have no effect.

The few that do have are very likely to increase that residual.



..... Phil

"Trevor Wilson"
Phil Allison wrote:


** Trevor cannot produce any real examples and he has scoured the planet
for
them.


**Incorrect:

** Try to follow the context - Trevor.

I know that is a burdensome task for you.

Are any of your "examples" for models that were in common use in the mid
1970s ??

I see none.

That makes then all irrelevant.

Further, posting a link to some graphs is not making a case.

Cos you have not got a case, only a foolish false assumption.



..... Phil

In article , Phil Allison
scribeth thus

"tony sayer"
Phil Allison


Peter Walker hated them all.


** Context missing here, "them" refers to audiophools.



I must admit I had *no idea* just how ****ing out of touch with reality
you were until now.

Believe whatever you like,cos there is no hope whatever for utter
****wits like you.


** Claiming the famous Peter Walker would *agree* with some of the
worst audiophool tripe imaginable is ****ING DESPICABLE !!!!!!!

Do calm down dearie and stop that selective out of context snipping
wontcha!..



Nope.. he was a very open minded gent

** He hated audiophools like you.

Not me sunshine, why you've got the wrong guy **


He made that very clear over an over in paid advertisements, interviews and
letters to Wireless World magazine.

But a stinking ****wit like you would have no idea these even exist.
---------------------------------------------------------------------------


Tony Sayer should be taken out and whipped for doing it.

Read the thread here,

1. Sayer claimed the Quad 405 had flawed sound.

It does have its shortcomings ..

** It does not have flawed sound.

I didn't say it was flawed you said that..


Peter Walker claimed it was audibly perfect when used as intended.

This claim was also proved in several public demonstrations and with
electronic precision by Peter Baxandall.

But a stinking ****wit like you would have no idea these even exist.
-----------------------------------------------------------------------------



2. He produced a quote from some audiophool at the BBC to back him up.


Yes some audiophool BBC engineers and studio managers

** Glad you agree.

Yes odd that his son had other ideas isn't it;?..


3. Then he claimed Peter Walker would agree.

Which he did..

** Agree the 405 had flawed sound?

I never said that YOU did !!!!!

Wot a STINKING LIE !!!!!!!!
---------------------------------------

You are a know nothing, ****ing ASS - Tony.

Get cancer a die in agony.


.... love, Phil

Anytime sweetie**

Perhaps we'd better let you rest your poor olde neurones for a while so
till next time ...








--
Tony Sayer

On 19/11/2013 9:51 AM, Phil Allison wrote:
"Trevor Wilson"
Phil Allison wrote:


** Trevor cannot produce any real examples and he has scoured the planet
for
them.


**Incorrect:

** Try to follow the context - Trevor.

I know that is a burdensome task for you.

Are any of your "examples" for models that were in common use in the mid
1970s ??

I see none.


**Infinity 4.5, Infinity 2.5, Infinity 1.5 (all ca. 1979). Infinity
Quantum Line Source, Quantum 2, Quantum 3, Quantum 4 (ca. 1977).

I have no impedance plots of these models, but they vary from extremely
difficult (Infinity 1.5 to damned near impossible (Infinity 4.5).


That makes then all irrelevant.

Further, posting a link to some graphs is not making a case.

**Really? How so? Thoe graphs demonstrate impedance curves that are
outside the capacity of the Quad 405 to deliver current without limiting.



Cos you have not got a case, only a foolish false assumption.

**Actually, I have considerably more than that. I was called in when the
Australian Infinity importer blew up several power amps on his, then
new, 4.5 speakers. Some rudimentary impedance measurements led me to
believe that someone in the factory had made a huge blunder during
assembly. Examining the schematic revealed some really dumb design
decisions, but no actual 'fault' with the speakers. The 2.5 and 1.5
models were less horrible to drive, but still impossible for a Quad 405
(and 99.99% of all amplifiers available).


--
Trevor Wilson www.rageaudio.com.au

"Trevor Wilson"
Phil Allison wrote:

** Trevor cannot produce any real examples and he has scoured the
planet
for them.


**Incorrect:

** Try to follow the context - Trevor.

I know that is a burdensome task for you.

Are any of your "examples" for models that were in common use in the mid
1970s ??

I see none.


**Infinity 4.5, Infinity 2.5, Infinity 1.5 (all ca. 1979). Infinity
Quantum Line Source, Quantum 2, Quantum 3, Quantum 4 (ca. 1977).

** Huh ?

Not mid 70s, not mentioned before and not in common use anywhere.

Wot a ****ing bull **** artist.


That makes then all irrelevant.

Further, posting a link to some graphs is not making a case.

**Really? How so? Thoe graphs demonstrate impedance curves that are
outside the capacity of the Quad 405 to deliver current without limiting.


** Nonsense.


Cos you have not got a case, only a foolish false assumption.

**Actually, I have considerably more than that.

** Correct for once - you have a massive number of false assumptions going
on simultaneously.

Cos your general ignorance of audio electronic theory is so wide.


Examining the schematic revealed some really dumb design decisions, but
no actual 'fault' with the speakers. The 2.5 and 1.5 models were less
horrible to drive, but still impossible for a Quad 405 (and 99.99% of all
amplifiers available).


** On those facts - the Quad 405 must be completely exonerated.

You have just been hoisted on your own petard.

****wit.


..... Phil

In article , Trevor Wilson
wrote:
On 19/11/2013 9:51 AM, Phil Allison wrote:
"Trevor Wilson" Phil Allison wrote:



**Infinity 4.5, Infinity 2.5, Infinity 1.5 (all ca. 1979). Infinity
Quantum Line Source, Quantum 2, Quantum 3, Quantum 4 (ca. 1977).

I have no impedance plots of these models, but they vary from extremely
difficult (Infinity 1.5 to damned near impossible (Infinity 4.5).

Yes. This was the era when I was designing a power amp for a living. During
which I did try out the 405 and current dumping and PJW/Mike Albinson did
discuss them with me with a view to Armstrong using the same approach.

However seeing the UK reactions to the original 405 and the way speaker
impedances and sensitivities seemed to he heading south I went for a design
that could happily poke out large currents and didn't have any explicit
limiter circuits.

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"


Yes. This was the era when I was designing a power amp for a living.
During
which I did try out the 405 and current dumping and PJW/Mike Albinson did
discuss them with me with a view to Armstrong using the same approach.


** Really .............


However seeing the UK reactions to the original 405 and the way speaker
impedances and sensitivities seemed to he heading south I went for a
design
that could happily poke out large currents and didn't have any explicit
limiter circuits.


** Shame it was basically a time bomb with a *short* fuse.

Your 723 deserves a prize for the most inadequately engineered BJT power
amp of all time.

A nasty accident looking for somewhere to happen.




.... Phil

On 19/11/2013 11:25, Phil Allison wrote:
"Jim Lesurf"


Yes. This was the era when I was designing a power amp for a living.
During
which I did try out the 405 and current dumping and PJW/Mike Albinson did
discuss them with me with a view to Armstrong using the same approach.


** Really .............


However seeing the UK reactions to the original 405 and the way speaker
impedances and sensitivities seemed to he heading south I went for a
design
that could happily poke out large currents and didn't have any explicit
limiter circuits.


** Shame it was basically a time bomb with a *short* fuse.

Your 723 deserves a prize for the most inadequately engineered BJT power
amp of all time.

A nasty accident looking for somewhere to happen.

I'm sure Uncle Clive's Project 60 Z30 amp would be a contender.

--
Eiron.

In article ,
Phil Allison wrote:
** Shame it was basically a time bomb with a *short* fuse.

Your 723 deserves a prize for the most inadequately engineered BJT
power amp of all time.

A nasty accident looking for somewhere to happen.

So which amp which made production did you design? No? Then shut the ****
up.

--
*We never really grow up, we only learn how to act in public.

Dave Plowman London SW
To e-mail, change noise into sound.

In article , Dave Plowman (News)
wrote:
In article , Phil Allison
wrote:
** Shame it was basically a time bomb with a *short* fuse.

Your 723 deserves a prize for the most inadequately engineered BJT
power amp of all time.

A nasty accident looking for somewhere to happen.

So which amp which made production did you design? No? Then shut the
**** up.

Since I've never designed a "723" I wonder what it had to do with anything
we'd said. But if he wants to criticise someone's "723" design I'd judge
that on the basis of him detailing his hands-on experience with one.

OTOH So far as I know, no Armstrong 730/732's ever even went to Aus. If any
did, I'd be interested to hear from their owners. The "fuses" on my two
pairs seem to be set to longer than 30 years so far. :-)

Admittedly during tests one day I did use up dozens of genuine fuses in
one. Did this by playing Led Zep at high levels and kept shorting the
output terminals with a large screwdriver. Each time the fuses blew I
replaced them and did it again. The only long term effect was I had to
change the output binding posts because each time it spot-welded the
screwdriver to them and had to drag it off again for the next attempt. Made
a bit of a mess of the threads on the binding posts. 8-]

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