I am looking for a 6SH7 tube it is red metal colour, with 6SH7 in black on
it is also the words Phillips & Kog

Its used in the New Quad II-forties mono block amplifiers

I know Quad buy them from US but not where, anyone any ideas?


Also which is the best? 5U4G?

"Dave xxxxx" ha scritto nel messaggio
...
I am looking for a 6SH7 tube it is red metal colour, with 6SH7 in black
on
it is also the words Phillips & Kog

If You want to replace just one tube and You care for aesthetics You'll have
some troubles: metal tubes like the 6SH7 are usually black.


Its used in the New Quad II-forties mono block amplifiers

I know Quad buy them from US but not where, anyone any ideas?

It is a relatively recent NOS tube; great lots were manufactured,
particularly as "JAN" (Joint Army & Navy strategic "spare parts"), but then
thermionic technology suddenly disappeared leaving many tubes unused, and
You can still find this particular pentode sold by the dozen. QUAD probably
made a deal with some major tubes "pusher" like Richardson or New Sensor and
only incidentally they bought Philips.
This doesn't happen for any NOS item: many are really scarce and valuable.
In this market the price tag is not a function of the real electronic
"merits" of a particular item, but it is fixed @ 99% by "offer and demand":
if You need a 7kb#@!! and there's only one left on Earth, You'll pay
Tiffany's prices for it.
Quad was wise in its choice of a readily available one. See as an example
http://www.house-of-tubes.com/catalo....asp?SKU=48941 (3$/each)



Also which is the best?

As I said You can only get NOS tubes, 'cause the 6SH7 is no longer produced
since (about) the Sixties. Any NOS tube in good state of conservation,
tested and meeting all specs for its type will be a good one. Generally
speaking, many people during listening tests tend to prefer the "louder"
tubes, ie. the ones having higher gain, 'cause they seem to sound more
"vivid". In fact they only have a mu approaching the higher threshold for
their type, which doesn't mean they're "better".
The only advice You can be given is to replace both tubes (when needed) with
a closely matched pair. The Quad II circuit does a big effort to balance
its intrinsically poorly balanced "see-saw" input/splitter/driver circuit,
but using a couple of pentodes having as close a gain as possible will ease
this effort and provide the best sound.


5U4G?

It is a rectifier. DC is DC. If You hear a difference among a brand and
another (provided that all match the specs), there are only two chances:

- You suffer from acoustic hallucinations
- Quad sold You a poorly designed power supply


WATCH OUT FOR SNAKE OIL!


Ciao

Fabio

"Fabio Berutti" said:

5U4G?

It is a rectifier. DC is DC. If You hear a difference among a brand and
another (provided that all match the specs), there are only two chances:

- You suffer from acoustic hallucinations
- Quad sold You a poorly designed power supply

Some 5U4Gs have a higher voltage loss than others.
A different B+ may lead to a slightly different sounding amp.

WATCH OUT FOR SNAKE OIL!

I have paper-in-snake-oil coupling caps in my amps.
Is that bad?

--
Sander deWaal
"SOA of a KT88? Sufficient."

"Sander deWaal" ha scritto nel messaggio
...
"Fabio Berutti" said:

5U4G?

It is a rectifier. DC is DC. If You hear a difference among a brand and
another (provided that all match the specs), there are only two chances:

- You suffer from acoustic hallucinations
- Quad sold You a poorly designed power supply

Some 5U4Gs have a higher voltage loss than others.
A different B+ may lead to a slightly different sounding amp.

1 - In fact I wrote "provided that all match the specs" / 2 - the rectifier
is not necessarily the one to blame for B+ variations. AC power supply is
allowed to perambulate by +/-10% around its nominal value, according to
"private user" contract (at least here in Italy). I suppose this has a much
larger effect on the resulting B+ / 3 - "different" is neither better nor
worse


WATCH OUT FOR SNAKE OIL!

I have paper-in-snake-oil coupling caps in my amps.
Is that bad?

There's a sound reason for using paper-in-oil caps along the signal path: as
You know they have the minimum hysteresys - most linear behavior - minimum
distortion: this is no magic at all. In real terms, the difference is small
and I wouldn't pay the extra price for the best Jensen paper-in-oil
copper-foil capacitors, in comparison with any good PP cap, unless I were
building a real top-end and top-$ unit. Example: my PushPull amp (6L6GC, UL
conn.) uses PolyPropylene signal caps, while the SE 2A3 is fitted with
Jensen capacitors.

I think that any component should be "proportioned" both in terms of quality
AND price with all the others, and all must fit into a well-engineered
schematic. A WE tube, a Jensen cap or a Tamura tranny are just wasted if
put in an unadequate unit.

Ciao
Fabio


--
Sander deWaal
"SOA of a KT88? Sufficient."

Fabio Berutti wrote:

"Dave xxxxx" ha scritto nel messaggio
...
I am looking for a 6SH7 tube it is red metal colour, with 6SH7 in black
on
it is also the words Phillips & Kog

If You want to replace just one tube and You care for aesthetics You'll have
some troubles: metal tubes like the 6SH7 are usually black.


Its used in the New Quad II-forties mono block amplifiers

I know Quad buy them from US but not where, anyone any ideas?

It is a relatively recent NOS tube; great lots were manufactured,
particularly as "JAN" (Joint Army & Navy strategic "spare parts"), but then
thermionic technology suddenly disappeared leaving many tubes unused, and
You can still find this particular pentode sold by the dozen. QUAD probably
made a deal with some major tubes "pusher" like Richardson or New Sensor and
only incidentally they bought Philips.
This doesn't happen for any NOS item: many are really scarce and valuable.
In this market the price tag is not a function of the real electronic
"merits" of a particular item, but it is fixed @ 99% by "offer and demand":
if You need a 7kb#@!! and there's only one left on Earth, You'll pay
Tiffany's prices for it.
Quad was wise in its choice of a readily available one. See as an example
http://www.house-of-tubes.com/catalo....asp?SKU=48941 (3$/each)



Also which is the best?

As I said You can only get NOS tubes, 'cause the 6SH7 is no longer produced
since (about) the Sixties. Any NOS tube in good state of conservation,
tested and meeting all specs for its type will be a good one. Generally
speaking, many people during listening tests tend to prefer the "louder"
tubes, ie. the ones having higher gain, 'cause they seem to sound more
"vivid". In fact they only have a mu approaching the higher threshold for
their type, which doesn't mean they're "better".
The only advice You can be given is to replace both tubes (when needed) with
a closely matched pair. The Quad II circuit does a big effort to balance
its intrinsically poorly balanced "see-saw" input/splitter/driver circuit,
but using a couple of pentodes having as close a gain as possible will ease
this effort and provide the best sound.

The Quad 40 circuit would benefit from the use of 6SH7,
which would be an infinitely superior tube compared to
the EF86 in Quad II.
The Quad 40 also has KT88, much better than KT66.
I wonder if the OPT is any better, I have never seen one.

Patrick Turner.



5U4G?

It is a rectifier. DC is DC. If You hear a difference among a brand and
another (provided that all match the specs), there are only two chances:

- You suffer from acoustic hallucinations
- Quad sold You a poorly designed power supply

WATCH OUT FOR SNAKE OIL!

Ciao

Fabio

Patrick Turner wrote:
Fabio Berutti wrote:


electronic "merits" of a particular item, but it is fixed @ 99% by
"offer and demand": if You need a 7kb#@!! and there's only one left
on Earth, You'll pay Tiffany's prices for it.
Quad was wise in its choice of a readily available one. See as an
example http://www.house-of-tubes.com/catalo....asp?SKU=48941
(3$/each)



Also which is the best?

As I said You can only get NOS tubes, 'cause the 6SH7 is no longer
produced since (about) the Sixties. Any NOS tube in good state of
conservation, tested and meeting all specs for its type will be a
good one. Generally speaking, many people during listening tests
tend to prefer the "louder" tubes, ie. the ones having higher gain,
'cause they seem to sound more "vivid". In fact they only have a mu
approaching the higher threshold for their type, which doesn't mean
they're "better".
The only advice You can be given is to replace both tubes (when
needed) with a closely matched pair. The Quad II circuit does a big
effort to balance its intrinsically poorly balanced "see-saw"
input/splitter/driver circuit, but using a couple of pentodes having
as close a gain as possible will ease this effort and provide the
best sound.

The Quad 40 circuit would benefit from the use of 6SH7,
which would be an infinitely superior tube compared to
the EF86 in Quad II.
The Quad 40 also has KT88, much better than KT66.
I wonder if the OPT is any better, I have never seen one.

Patrick Turner.

Its much better than the OPT on the Quad II over built is an understatement


A few pictures on here
http://www.davewhitter.pwp.blueyonde...ew%20pics2.htm

Also a few of a NOS Quad II still boxed never plugged in lost for years at
the back of a stock room



--
Dave xxxx
www.davewhitter.myby.co.uk

Music is Art - Audio is Engineering
Steam is Fun

Dave xxxxx wrote:
I am looking for a 6SH7 tube it is red metal colour, with 6SH7 in black on
it is also the words Phillips & Kog


The color of the paint on the metal of the tube matters little
other than for looks. If that is a concern, you could just
paint a regular 6SH7 to match the others already in the amp.