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Trevor Wilson Trevor Wilson is offline
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Default Luxman SQ38D

Does anyone have a schematic for a Luxman SQ38D? I mostly require info
on the tone amp section. The one I have has been modified and I need to
restore it to standard.

TIA
--
Trevor Wilson www.rageaudio.com.au
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Phil Allison[_3_] Phil Allison[_3_] is offline
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Default Luxman SQ38D


"Trevor Wilson"

Does anyone have a schematic for a Luxman SQ38D? I mostly require info on
the tone amp section. The one I have has been modified and I need to
restore it to standard.



** The " SQ38D" was released in Japan in 1965 - do you really have one of
them ?

A long series of " SQ38 " amps were released including the "SQ-38D" in
1998.

http://www.onahighernote.com/luxman/?c=5&id=45

Earlier models had triode output valves ( 6RA8s ) made in Japan, later ones
uses regular 6BQ5s.

Luxman schems were always near impossible to obtain - certainly so here in
Australia.


..... Phil


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Trevor Wilson Trevor Wilson is offline
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Default Luxman SQ38D

On 11/13/2012 11:11 AM, Phil Allison wrote:
"Trevor Wilson"

Does anyone have a schematic for a Luxman SQ38D? I mostly require
info on the tone amp section. The one I have has been modified and
I need to restore it to standard.



** The " SQ38D" was released in Japan in 1965 - do you really have
one of them ?


**I REALLY do have one of them. In pristine nick too. This being the
beastie in question:

http://www.thevintageknob.org/luxman-SQ38D.html



A long series of " SQ38 " amps were released including the "SQ-38D"
in 1998.

http://www.onahighernote.com/luxman/?c=5&id=45

Earlier models had triode output valves ( 6RA8s ) made in Japan,
later ones uses regular 6BQ5s.

Luxman schems were always near impossible to obtain - certainly so
here in Australia.


**Some were. I have a half a filing cabinet drawer full. Mostly solid
state though. A legacy of being a major service agent for the product
from 1980 'till Interdyn let go of the product. In fact, I have a few
doubles if you need anything.


--
Trevor Wilson www.rageaudio.com.au
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Phil Allison[_3_] Phil Allison[_3_] is offline
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Default Luxman SQ38D


"Trevor Wilson"
Phil Allison wrote:
"Trevor Wilson"

Does anyone have a schematic for a Luxman SQ38D? I mostly require
info on the tone amp section. The one I have has been modified and
I need to restore it to standard.



** The " SQ38D" was released in Japan in 1965 - do you really have
one of them ?


**I REALLY do have one of them. In pristine nick too. This being the
beastie in question:

http://www.thevintageknob.org/luxman-SQ38D.html



** Where do you get 6RA8 output triodes these days ??


Luxman schems were always near impossible to obtain - certainly so
here in Australia.


**Some were. I have a half a filing cabinet drawer full. Mostly solid
state though. A legacy of being a major service agent for the product
from 1980 'till Interdyn let go of the product.



** Luxman was sold and supported by L&G Hoskins in NSW through the 70s and
80s. They also sold Alpine cassette decks and Celestion speakers.

They adopted the name "Quality Hi-Fi" in 1976 and are still trading under
it.

http://www.qualityhifi.com.au/files/about_us.html

I was alluding to them when I said schems were impossible to get - there
was more chance of getting blood from a stone than having Gordon Hoskins
part with a schematic for any of his products.

What a Neanderthal.



..... Phil


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"Phil Allison"

** Where do you get 6RA8 output triodes these days ??


** Found some he

http://www.ebay.com/itm/6R-A8-6RA8-N...em3c cbd573cd



Not cheap ...



..... Phil




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Default Luxman SQ38D

On 11/13/2012 1:22 PM, Phil Allison wrote:
"Trevor Wilson"
Phil Allison wrote:
"Trevor Wilson"

Does anyone have a schematic for a Luxman SQ38D? I mostly require
info on the tone amp section. The one I have has been modified and
I need to restore it to standard.


** The " SQ38D" was released in Japan in 1965 - do you really have
one of them ?


**I REALLY do have one of them. In pristine nick too. This being the
beastie in question:

http://www.thevintageknob.org/luxman-SQ38D.html



** Where do you get 6RA8 output triodes these days ??


**Buggered if I know. The ones in the amp I have are OK (admittedly, a
very short test).



Luxman schems were always near impossible to obtain - certainly so
here in Australia.


**Some were. I have a half a filing cabinet drawer full. Mostly solid
state though. A legacy of being a major service agent for the product
from 1980 'till Interdyn let go of the product.



** Luxman was sold and supported by L&G Hoskins in NSW through the 70s and
80s. They also sold Alpine cassette decks and Celestion speakers.


**Actually, I believe Interdyn was the importer of Luxman since the
1960s. I think they had an exclusive with Hoskins 'till the early 1990s
for NSW. I could be wrong though. I recall trying to obtain information
from Hoskins during the 1980s. It was almost impossible.


They adopted the name "Quality Hi-Fi" in 1976 and are still trading under
it.

http://www.qualityhifi.com.au/files/about_us.html

I was alluding to them when I said schems were impossible to get - there
was more chance of getting blood from a stone than having Gordon Hoskins
part with a schematic for any of his products.


**Difficult, but not impossible. I did some service work for them for a
few years last century. I can probably still obtain a manual if I need
one. The trick is knowing who to talk to.


What a Neanderthal.


**You got that right.

--
Trevor Wilson www.rageaudio.com.au
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Default Luxman SQ38D


"Trevor Wilson"
Phil Allison wrote:
"Trevor Wilson"


** The " SQ38D" was released in Japan in 1965 - do you really have
one of them ?

**I REALLY do have one of them. In pristine nick too. This being the
beastie in question:

http://www.thevintageknob.org/luxman-SQ38D.html



** Where do you get 6RA8 output triodes these days ??


**Buggered if I know. The ones in the amp I have are OK (admittedly, a
very short test).



** The amp you have is not a 240V model, is it ?

More like 100V, straight from Japan via Ebay ??



What a Neanderthal.


**You got that right.



** LOL :-) ....



..... Phil



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Default Luxman SQ38D

On 11/13/2012 1:47 PM, Phil Allison wrote:
"Phil Allison"

** Where do you get 6RA8 output triodes these days ??


** Found some he

http://www.ebay.com/itm/6R-A8-6RA8-N...em3c cbd573cd



Not cheap ...



.... Phil



**Thanks for that. If I need them, I know I can probably buy them.
Fortunately, the amp is worth a couple of grand (I'll be selling it
after re-building), so a few hundred for new valves is worth it.

--
Trevor Wilson www.rageaudio.com.au
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Default Luxman SQ38D

On 11/13/2012 2:06 PM, Phil Allison wrote:
"Trevor Wilson"
Phil Allison wrote:
"Trevor Wilson"


** The " SQ38D" was released in Japan in 1965 - do you really have
one of them ?

**I REALLY do have one of them. In pristine nick too. This being the
beastie in question:

http://www.thevintageknob.org/luxman-SQ38D.html


** Where do you get 6RA8 output triodes these days ??


**Buggered if I know. The ones in the amp I have are OK (admittedly, a
very short test).



** The amp you have is not a 240V model, is it ?

More like 100V, straight from Japan via Ebay ??


**Nope. Genuine 240VAC 50Hz/60Hz label on the back. An ancient
Australian mains plug on the lead too. AFAIK, it has probably been owned
by the original purchaser for many decades.




What a Neanderthal.


**You got that right.



** LOL :-) ....



.... Phil


**FWIW, I was speaking to one of the guys down at Interdyn a few weeks
back. He was ****ed off. Management instructed them to dispose of many
filing cabinets full of old service manuals and boxes of old spare
parts. Many were Luxman items. Idiots. They could have sold it all for
good money.


--
Trevor Wilson www.rageaudio.com.au
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patrick-turner patrick-turner is offline
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Default Luxman SQ38D

On 13 Nov, 11:11, "Phil Allison" wrote:
"Trevor Wilson"



Does anyone have a schematic for a Luxman SQ38D? I mostly require info on
the tone amp section. The one I have has been modified and I need to
restore it to standard.


** The " SQ38D" *was released in Japan in 1965 *- *do you really have one of
them ?

A long series of *" SQ38 " *amps were released including the "SQ-38D" in
1998.

http://www.onahighernote.com/luxman/?c=5&id=45

Earlier models had triode output valves ( 6RA8s ) made in Japan, later ones
uses regular 6BQ5s.

Luxman schems were always near impossible to obtain - certainly so here in
Australia.

.... *Phil


What's wrong with Trevor? All he has to do is sit there for awhile and
draw the schematic from what he sees, and then work out how it works,
or should work, bearing in mind any mods he should be able to see, and
then, once he understands what he's doing, he can properly check the
darn thing out. Even with a schematic, a good tube tech draws the
schematic anyway, and completely familiarizes himself where everything
is on the schematic. Its all so much more logical than trying to draw
a Luxman SS amp circuit. I've had 3 tubed Luxmans come to me for a
fix, one had 6868, and they were so expensive in 1995 that I replaced
them with EL34 & sockets after making the case taller. The next had
some strange OP tetrode but had two blown OPTs, so its still here
after 12 years. The next can with strange 12 pin tubes with 50V
heaters and a missing OPT which another tech had lost, so the OPT
musta fused. It stayed awhile, then I reused the chassis for something
far better of my own design with 2 x EL34, and some better wound-in-Oz
PT and OPTs. I reused a choke. Below Trev says he want to sell the
Luxman for $2,000 after paying hundreds for new rare tubes unlikely to
be available when the next time comes arounf for replacement. What's
anyone got for 2 grand? Just another lack lustre tube amp, with maybe
very used/traumatised OPTs after possible episodes of overheating
tubes. Luxmans are supposed to have "Mystique", good "Karma" or "Aura"
but I don't see it. I get a number of ancient POS amps coming here for
singing lessons and quit-smoking therapy. All very sacred old brands,
but not one is a sacred cow, so I usually gut the lot and start all
over again. Just finished a pair of POS Jadis SE300B amps. No other
way to make 'em behave.
Patrick Turner.


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Default Luxman SQ38D

On 11/13/2012 7:29 PM, patrick-turner wrote:
On 13 Nov, 11:11, "Phil Allison" wrote:
"Trevor Wilson"



Does anyone have a schematic for a Luxman SQ38D? I mostly require info on
the tone amp section. The one I have has been modified and I need to
restore it to standard.


** The " SQ38D" was released in Japan in 1965 - do you really have one of
them ?

A long series of " SQ38 " amps were released including the "SQ-38D" in
1998.

http://www.onahighernote.com/luxman/?c=5&id=45

Earlier models had triode output valves ( 6RA8s ) made in Japan, later ones
uses regular 6BQ5s.

Luxman schems were always near impossible to obtain - certainly so here in
Australia.

.... Phil


What's wrong with Trevor?


**Nothing wrong with me. Using a published schematic (if available) is
MUCH quicker and expedient that re-engineering an amplifier that has
been modified by a third party. I simply wish to restore the amp to it's
original spec in readiness for sale. The amplifier has been modified by
another tech such that it no longer performs as it did when first made.
I can certainly make some educated calculations about the appropriate
component values and choices, but it is much easier to use the original
components.


All he has to do is sit there for awhile and
draw the schematic from what he sees,


**And again: The tone amplifier stage has been substantially modified.
It no longer resembles the original topology. Drawing out what is there
would be a waste of time.


and then work out how it works,
or should work, bearing in mind any mods he should be able to see, and
then, once he understands what he's doing, he can properly check the
darn thing out. Even with a schematic, a good tube tech draws the
schematic anyway, and completely familiarizes himself where everything
is on the schematic. Its all so much more logical than trying to draw
a Luxman SS amp circuit. I've had 3 tubed Luxmans come to me for a
fix, one had 6868, and they were so expensive in 1995 that I replaced
them with EL34 & sockets after making the case taller. The next had
some strange OP tetrode but had two blown OPTs, so its still here
after 12 years. The next can with strange 12 pin tubes with 50V
heaters and a missing OPT which another tech had lost, so the OPT
musta fused. It stayed awhile, then I reused the chassis for something
far better of my own design with 2 x EL34, and some better wound-in-Oz
PT and OPTs. I reused a choke. Below Trev says he want to sell the
Luxman for $2,000 after paying hundreds for new rare tubes unlikely to
be available when the next time comes arounf for replacement. What's
anyone got for 2 grand? Just another lack lustre tube amp, with maybe
very used/traumatised OPTs after possible episodes of overheating
tubes. Luxmans are supposed to have "Mystique", good "Karma" or "Aura"
but I don't see it. I get a number of ancient POS amps coming here for
singing lessons and quit-smoking therapy. All very sacred old brands,
but not one is a sacred cow, so I usually gut the lot and start all
over again. Just finished a pair of POS Jadis SE300B amps. No other
way to make 'em behave.
Patrick Turner.


**Whether the amp is good, bad or indifferent, is not the issue and I
don't much care either way. It is a desirable object for many people.
Kinda like a Model T Ford. Try and explain to a T Ford owner that a 2012
Ford Mustang is a vastly superior vehicle in every way. You'll get
nowhere fast.



--
Trevor Wilson www.rageaudio.com.au
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patrick-turner patrick-turner is offline
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Default Luxman SQ38D

On 14 Nov, 06:42, Trevor Wilson
wrote:
On 11/13/2012 7:29 PM, patrick-turner wrote:





On 13 Nov, 11:11, "Phil Allison" wrote:
"Trevor Wilson"


Does anyone have a schematic for a Luxman SQ38D? I mostly require info on
the tone amp section. The one I have has been modified and I need to
restore it to standard.


** The " SQ38D" *was released in Japan in 1965 *- *do you really have one of
them ?


A long series of *" SQ38 " *amps were released including the "SQ-38D" in
1998.


http://www.onahighernote.com/luxman/?c=5&id=45


Earlier models had triode output valves ( 6RA8s ) made in Japan, later ones
uses regular 6BQ5s.


Luxman schems were always near impossible to obtain - certainly so here in
Australia.


.... *Phil


What's wrong with Trevor?


**Nothing wrong with me.


Trevor, you are such a great big fukken dope, you don't know that you
are one, and its been like this all the time I've known you.

I can't and won't help you. Go fix your amp like I've had to fix
dozens, all without schematics.

Just do it.

Patrick Turner


Using a published schematic (if available) is
MUCH quicker and expedient that re-engineering an amplifier that has
been modified by a third party. I simply wish to restore the amp to it's
original spec in readiness for sale. The amplifier has been modified by
another tech such that it no longer performs as it did when first made.
I can certainly make some educated calculations about the appropriate
component values and choices, but it is much easier to use the original
components.

* All he has to do is sit there for awhile and

draw the schematic from what he sees,


**And again: The tone amplifier stage has been substantially modified.
It no longer resembles the original topology. Drawing out what is there
would be a waste of time.

* and then work out how it works,





or should work, bearing in mind any mods he should be able to see, and
then, once he understands what he's doing, he can properly check the
darn thing out. Even with a schematic, a good tube tech draws the
schematic anyway, and completely familiarizes himself where everything
is on the schematic. Its all so much more logical than trying to draw
a Luxman SS amp circuit. I've had 3 tubed Luxmans come to me for a
fix, one had 6868, and they were so expensive in 1995 that I replaced
them with EL34 & sockets after making the case taller. The next had
some strange OP tetrode but had two blown OPTs, so its still here
after 12 years. The next can with strange 12 pin tubes with 50V
heaters and a missing OPT which another tech had lost, so the OPT
musta fused. It stayed awhile, then I reused the chassis for something
far better of my own design with 2 x EL34, and some better wound-in-Oz
PT and OPTs. I reused a choke. Below Trev says he want to sell the
Luxman for $2,000 after paying hundreds for new rare tubes unlikely to
be available when the next time comes arounf for replacement. What's
anyone got for 2 grand? Just another lack lustre tube amp, with maybe
very used/traumatised OPTs after possible episodes of overheating
tubes. Luxmans are supposed to have "Mystique", good "Karma" or "Aura"
but I don't see it. I get a number of ancient POS amps coming here for
singing lessons and quit-smoking therapy. All very sacred old brands,
but not one is a sacred cow, so I usually gut the lot and start all
over again. Just finished a pair of POS Jadis SE300B amps. No other
way to make 'em behave.
Patrick Turner.


**Whether the amp is good, bad or indifferent, is not the issue and I
don't much care either way. It is a desirable object for many people.
Kinda like a Model T Ford. Try and explain to a T Ford owner that a 2012
Ford Mustang is a vastly superior vehicle in every way. You'll get
nowhere fast.

--
Trevor Wilsonwww.rageaudio.com.au- Hide quoted text -

- Show quoted text -- Hide quoted text -

- Show quoted text -


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On 11/14/2012 10:57 AM, patrick-turner wrote:
On 14 Nov, 06:42, Trevor Wilson
wrote:
On 11/13/2012 7:29 PM, patrick-turner wrote:





On 13 Nov, 11:11, "Phil Allison" wrote:
"Trevor Wilson"


Does anyone have a schematic for a Luxman SQ38D? I mostly require info on
the tone amp section. The one I have has been modified and I need to
restore it to standard.


** The " SQ38D" was released in Japan in 1965 - do you really have one of
them ?


A long series of " SQ38 " amps were released including the "SQ-38D" in
1998.


http://www.onahighernote.com/luxman/?c=5&id=45


Earlier models had triode output valves ( 6RA8s ) made in Japan, later ones
uses regular 6BQ5s.


Luxman schems were always near impossible to obtain - certainly so here in
Australia.


.... Phil


What's wrong with Trevor?


**Nothing wrong with me.


Trevor, you are such a great big fukken dope, you don't know that you
are one, and its been like this all the time I've known you.

I can't and won't help you. Go fix your amp like I've had to fix
dozens, all without schematics.

Just do it.

Patrick Turner


**Thanks for your input Patrick.

I'll ask you one question:

How would YOU go about ascertaining the original values of the
components in a tone amp stage, without access to the original
schematics, parts lists, or even the original parts from the amplifier?

If it makes you happy, continue with your innane insults. For my part, I
asked a reasonable question. I even received a reasonable response from
PA. Your response is nothing short of insane.


--
Trevor Wilson www.rageaudio.com.au
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On 14 Nov, 11:12, Trevor Wilson
wrote:
On 11/14/2012 10:57 AM, patrick-turner wrote:





On 14 Nov, 06:42, Trevor Wilson
wrote:
On 11/13/2012 7:29 PM, patrick-turner wrote:


On 13 Nov, 11:11, "Phil Allison" wrote:
"Trevor Wilson"


Does anyone have a schematic for a Luxman SQ38D? I mostly require info on
the tone amp section. The one I have has been modified and I need to
restore it to standard.


** The " SQ38D" *was released in Japan in 1965 *- *do you really have one of
them ?


A long series of *" SQ38 " *amps were released including the "SQ-38D" in
1998.


http://www.onahighernote.com/luxman/?c=5&id=45


Earlier models had triode output valves ( 6RA8s ) made in Japan, later ones
uses regular 6BQ5s.


Luxman schems were always near impossible to obtain - certainly so here in
Australia.


.... *Phil


What's wrong with Trevor?


**Nothing wrong with me.


Trevor, you are such a great big fukken dope, you don't know that you
are one, and its been like this all the time I've known you.


I can't and won't help you. Go fix your amp like I've had to fix
dozens, all without schematics.


Just do it.


Patrick Turner


**Thanks for your input Patrick.

I'll ask you one question:

How would YOU go about ascertaining the original values of the
components in a tone amp stage, without access to the original
schematics, parts lists, or even the original parts from the amplifier?

If it makes you happy, continue with your innane insults. For my part, I
asked a reasonable question. I even received a reasonable response from
PA. Your response is nothing short of insane.



Trevor Wilson is an idiot, and one who has always hated having people
tell him he is what he calls others, ie, insane. Since I began
discussing audio tech matters with this idiot in 2002 or therabouts he
has never ever displayed any capability to really understand basic amp
design issues generally, and has never ever designed and built any
amplifier from what he knows alone. Trevor has always paraded his
gross mental disabilities especially when dealing with anything with a
vacuum tube in it. He complains I insult him, but I merely point out
the inconvenient truth about the man.
Trevor has always been extremely stubborn and unable and far too lazy
to understand that one really has to analyse properly when schematics
of gear are unavailable, and also when they are. He fails dismally to
be willing or able to draw up the schematic of a tube amp properly and
confidently and fully, and then make intelligent mods or repairs, and
in conjunction with measuring all voltages and currents and plotting
graphs of F response. AFAIK, there is absolutely nothing at his
website to prove he knows much. Last time I discussed anything at
aus.hi-fi or anywhere else it alsways ended in acrimony because he
would not accept that the CEO ME solid state amps should have been and
should be far more forthcoming with full schematics required for these
very over complicated amps made in Oz until they went broke. Trev
would have needed the schematics because he'd have no idea how to
otherwise proceed. I have fixed a number of SS amps without schemas,
after careful analysis. But I now won't provide any repair service for
any SS amps, because I am rather slow compared to a couple of very
rare good SS techs who are so much better and faster and cheaper than
Trevor will ever be, and besides, I have a huge pile of tube gear to
fix, many speculative projects done for the sake of doing them, and I
have officially retired. So I don't need to learn any more than I have
about SS junk.

I won't be explaining again to Trevor about how to suck eggs. Once is
a enough. Its like explaining to a gum tree how to be a ballerina. I
refuse to assist him in answering his questions while he refuses to
think and consider things himself, in his time, not mine.

All his questions so far are very easy for a good tube amp repairist
to answer. Tube amps are far simpler and easier to understand than
most SS. I refuse to spoonfeed Trevor, but if he travels to a store
selling kitchen gear I am sure he'll find a nice big wooden spoon to
feed himself with, while furiously studying RDH4 and many other books
he should have bought and read. There are umpteen websites out there
full of info for Trevor. He could do a lot worse than read my website
about what's needed in a good tube amp but interpolating my info into
a Luxman without becoming well be-fuddled would probably not be
possible.

I might add its amazing to see that PA has gained some notably worthy
control over his past habits of demolishing stupid ideas and arguments
put forward by Trevor - ad-nausem, or by anyone else, and over many
years. Fact is, many demolitions were very justified and correct
because PA knows far more than most others who have ever stepped a
foot inside this joint. He frightened so many wannabes who liked to
jarg the jargon, with ignorance. As people soon learn here, while I
have little time for fools, I am not perfect, and cannot be perfect,
and I don't mind that I fukkin ain't perfect.

I admit mistakes and my limitations, and with this attitude the
tantrums ppl chuck don't work with me, and nor will petulant whinging.
I will only give credit where its due, and statements of facts need to
be supported, and I can only respect diligence in others as I might
respect it in myself. I would suggest I won't change until I am laying
on a slab somewhere looking like a very nice corpse, ready for a warm
trip uppa chimney someplace.
Patrick Turner.


--
Trevor Wilsonwww.rageaudio.com.au- Hide quoted text -

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"Trevor Wilson"

**Thanks for your input Patrick.

I'll ask you one question:

How would YOU go about ascertaining the original values of the components
in a tone amp stage, without access to the original schematics, parts
lists, or even the original parts from the amplifier?

If it makes you happy, continue with your innane insults. For my part, I
asked a reasonable question. I even received a reasonable response from
PA. Your response is nothing short of insane.



** The Turneroid has never quite been the same since he fell for British
audio designer Susan Parker.

http://www.susan-parker.co.uk/

http://www.audiophonics.com/index.html

He lost his cool completely when I dubbed her "Dopey Sue" for making a
fundamental error regarding power mosfets.

Since Sue married her long time girlfriend a few years back - Pat has been
all but inconsolable.



..... Phil







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Default Luxman SQ38D

On 15 Nov, 14:14, "Phil Allison" wrote:
"Trevor Wilson"



**Thanks for your input Patrick.


I'll ask you one question:


How would YOU go about ascertaining the original values of the components
in a tone amp stage, without access to the original schematics, parts
lists, or even the original parts from the amplifier?


If it makes you happy, continue with your innane insults. For my part, I
asked a reasonable question. I even received a reasonable response from
PA. Your response is nothing short of insane.


** The Turneroid has never quite been the same since he fell for British
audio designer Susan Parker.

http://www.susan-parker.co.uk/

http://www.audiophonics.com/index.html

He lost his cool completely when I dubbed her "Dopey Sue" *for making a
fundamental error regarding power mosfets.

Since Sue married her long time girlfriend a few years back - *Pat has been
all but inconsolable.

.... * Phil


Yes, broke my heart it did, but we remain excellent friends, a far
better arrangement than having to work around a lady's unpredictble
emotional condition.

I'd not want to wonder very long about who you may be married to, but
i'd not be surprised if it was Ms Handandfingers.

I find that sue has some excellent ideas about transformers and about
simplicity. But she's been unable to focus much on her audio hobby
interests because of her heavy committments to well paying job at a
university.

Is the **** about mosfets the only thing you're cranky about today?

Patrick Turner.

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Phil Allison[_3_] Phil Allison[_3_] is offline
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"patrick-turner"
"Phil Allison"
"Trevor Wilson"

**Thanks for your input Patrick.


I'll ask you one question:


How would YOU go about ascertaining the original values of the
components
in a tone amp stage, without access to the original schematics, parts
lists, or even the original parts from the amplifier?


If it makes you happy, continue with your innane insults. For my part, I
asked a reasonable question. I even received a reasonable response from
PA. Your response is nothing short of insane.


** The Turneroid has never quite been the same since he fell for British
audio designer Susan Parker.

http://www.susan-parker.co.uk/

http://www.audiophonics.com/index.html

He lost his cool completely when I dubbed her "Dopey Sue" for making a
fundamental error regarding power mosfets.

Since Sue married her long time girlfriend a few years back - Pat has been
all but inconsolable.


Yes, broke my heart it did, but we remain excellent friends, a far
better arrangement than having to work around a lady's unpredictble
emotional condition.


** IME - working around unpredictable female emotions is a hazard for all.


I find that sue has some excellent ideas about transformers and about
simplicity.

** Simple, even elegant but very far from inexpensive.


But she's been unable to focus much on her audio hobby
interests because of her heavy committments to well paying job at a
university.


** The uni's workshops must be where she gets all that nice metalwork and
cabinetry done.

Foreign orders anyone ??


..... Phil



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patrick-turner patrick-turner is offline
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But she's been unable to focus much on her audio hobby
interests because of her heavy committments to well paying job at a
university.

** The uni's workshops must be where she gets all that nice metalwork and
cabinetry done.

* * Foreign orders anyone ??


I doubt it. Unfortunately, perhaps you don't know Susan as well as I
do, and bearing in mind your own difficulties with females and your
sprinklings of negativity I can only smile at your comments, and I
hope in that in the fullness of time you would find a wealth of
personal pleasures to be had where you wouldn't dream of dissmissing
so many people because you can gain access to their wit, their
determination to genuinely discuss things, and other wondrous facets
of human bevaiour so that you benefit as they might, without duress,
or verbal scaldings of boiling oil when there are inevitable
dissagreements, as indeed there must be for any of us to attain
wisdom.

Well you may complain about the costs of building a minimamlist
amplifier with just an input tranny and output tranny and 2 N mosfets
in source follower mode and class A. Ah, but the cost you say -
hopeless silly effort. Indeed cost is high, but all hobbies are all a
waste of time and money when that time and money could be put towards
fine charitable causes, or medical research, or R&D for a company
wanting to make 1 square metre solar panels that are 50% efficient for
$2 each, with lightweight batteries to go with them. Surely the
persuit of listening to music with valve amps is a true monumental
waste of human resources, and you'd prefer them all to beat a path to
your door to get advice on how to make an amp for $3, weighing less
than 100 grams and 99% efficient. Of course that's exactly where the
audio industry had headed with PWM amps fed by digital audio signals,
so the world beat you to it. Its another huge tragic waste that the
world wants 6.1 home theatre, with screens 10 feet wide and suburban
houses which compete with those owned by Louis IXV, and of course
everyone needs 2 cars each and they want to each eat enough to feed a
family of 16 Africans, and only vote for parties that give out yet
more Guvvy assistance. They then spnd hundreds of thousands on
expensive messy acrimonious divorces, and while learning nothing,
repeat it all. So I see your point in complaining about the cost of
Susan's minimalism approach. Don't worry, she more than compensates by
not having children and living a very simple life while owning a push
bike, while battling on in a maddening world.

I'm left wondering also about what became of your website? Where has
it gone? But then it dawned on me that perhaps you never got around to
inviting the world to your mind, so they may see how good audio could
be achieved. Was it all too vain and selfish to make a website? That's
a real pity considering you have vast knowledge. Nobody I know, except
possibly someone who might be your twin, would frown on having a
website.

In 1990 I frivolously built a pair class A amps with 4 mosefts with an
OPT. Mosfets are driven by LTP with 2 garden variety bjts in LTP and
one for a CCS. It has cap coupling, and works just fine, and gives 40
Watts in class A with THD 0.3%. I've never found anyone to say it
sounds worse than a tube amp with 4 x EL34 etc, and one may wonder why
I made these things but I enjoyed the experience and it taught me
more. One of these days I may convert it to Circlotron and have a pair
of EL84 as input/drivers, but I may never find the time.

Susan's amp has a step up input tranny with 600 ohms impedance. The 2V
input must be raised to roughly 30V output for gate to gate drive, and
to get input Z = 600r, the sec load must be 136k, and if Sec C load =
100pF, then Cin at Pri = 0.022uF. I'm guesstimating here but HF roll
off would trouble many people unless thay had a very low drive source
powering the IPT and if they didn't have a decent IPT.
Sue just uses a power mosfet as source follower to drive the IPT. The
lower the drive source Z, the less the characteristics of IPT and OPT
will cause distortions. Of course many say its a waste, but it matters
not, and the status quo is stained by productions governed by
accountants, and anything other than what mainstream industry does
becomes invalid.

Anyway, using a pair of EL84 in triode with Ra = 2k5 to drive perhaps
50pF of input C at gates seems a reasonable solution. Having mosfets
in circlotron with simple OPT means you have matching devices, and if
Vds on each mosfet is 20Vrms, then gate drive = about 10.5Vrms Vg-0V,
and the amp Rout is low enough and because class A, and ß = 0.5 and
open loop mosfet A = about 20, then THD is low, bandwidth vert wide,
and so you get hi-fi, fairly simply, without GNFB, or an IPT. The OPT
is probably best if an auto tranny, and can have 8 ohms input end to
end for 50 Watts of output with 20Vrms. If OPT core = 50mm stack of
50mm tongue E&I with partial air gapping for µe = 3,000, then wire
size is large and its quite easy to wind. On each side of PP circuit I
think a good load is 32 ohms for each of 4 class A mosfets, so that
all four drive the OPT primary of 8 ohms. Taps for 4 ohms and 2 ohms
are easy but I'm still not sure of HF performance because with say 2
ohms, using 1/2 the total auto tranny turns, the leakage inductance
affects the HF pole.
I'm trying to figure out a decent winding set up that allows many Z
combinations so as RL is lowered, the class A action remains and the
amp doesn't move into class AB.

There doesn't seem to be very much online about making audio auto-
trannies with very low winding losses and HF losses for Z range
between say 1 ohm and 64 ohms. Having an auto tranny which gave say 64
ohms to 4 ohms would be a boon to owners of tubed OTL amps. They tend
to become dissolutioned by OTL tubes suffering bias failure from
overheating due to the inevitable very poor load matching even with
multiple 6C33c output tubes. The load line analysis I've done on 6C33c
indicates good class A is available if Ea = +160V and RLa = 250r, and
Pda = 60W with Ia at around 370mA. 4 such tubes in class A can give
40Watts, and OPT primary RL can be 62.5 ohms. To my mind, this is
superior to using the same tubes hooked directly to 8 ohms and forcing
tubes on each side of PP circuit with low bias, and in class AB2, to
each produce say 1.4 amp peak current. 40W into 8 ohms is 3.15 peak
amps, so at least 6 x 6C33c are wise, and Pda with continuous signal
invites smoke, and things get worse with 4 ohms. Auiophile say they
like the transparency of OTL, but all OTL I've seen have a very large
amount of NFB applied, and its NFB that improves the sound, rather
than the absence of OPT.

But I digress.

I hope Trevor has by now worked out what is the best tone control with
tubes, IMHO, ( apart from scrapping tone control completely and
loudness function ). It is achieved with cathode follower input
driving a Baxandal type R&C circuit within a unity gain shunt FB
network So at least 2 halves of 12AX7 are needed for 1 channel.
Usually such unity gain tone control stages do not color sound and
nobody I know can tell when they in the circuit and not being
bypassed. Such
circuits may be left in circuit un-bypassed and they provide a low
Rout drive to volume control pot immediately before power amps. But
line stage gain and power amp gains need careful study. Most ancient
amps have high sensitvity because line-in source levels were 200mV, or
less, like Leak, with 100mV, because ppl hated paying more the extra
tube needed to get phono amp output higher when using a lone EF86 per
channel, etc.

Lord knows what might be in the SQ38D Luxmam, but typical tone control
circuits in 1960 used 1 x 12AU7 to raise signal by 22dB, then feed
that to a passive high value R log pots and C etc with very little
overall gain. Such old amplifiers with such tone controls usually
suffered C value drift and pots became noisy, and 12AU7 has no NFB so
it puts in 2% THD, and I am no fan of ancient stuff this way and they
are best reformed with unity gain with FB and linear pots. It means
gutting and re-wiring, and many hours of work. Usually the rest of all
such Old Junk amps also need gutting, re-designing, then re-wiring. I
have several here awaiting My Treatments. One has to end up doing what
bean counters dissallowed in 1960. Such old junk then sounds at its
possible best, which can be "brilliantus maximus", with quite low THD
and noise, with both channels having equal gain and phase shift so
image is good.

Its very rewarding work to do. I used to re-engineer some SS amps, eg,
Phlame Linear, but after awhile it seemed like cleaning toilets, I
dunno why, but at least I reduced the Phlame factor and smoke.

I have a pair of ancient 30 Watt RCA amps in the pile, 2 x EF86 + 2 x
KT66. Hmm, a delicious opportunity to make 'em much better, but I
don't know whay they were parked by owner 30 years ago - maybe new
OPTs are needed! Trevor would be unable to persue me for a better
mission plan than the one I might use myself - Draw up the existing
schematic, think about it for a couple of days, decide what to change,
check available space for parts left out in 1960, draw up everything
properly, leave room for flexibility for changes during the process.
Pay attention to switches on front panel. Typical 1960 amps were
riddled with Do-Dah switches for tape monitor, hi-lo cuts, and pahse
of signals. These are all best omitted from the new design, and often
I have had to make a new front panel with less stuff&junk on it. Often
more tag strips need installing, plus far better electros and new Si
diodes to replace tube rectifier/s. Often IEC socket plugs are wise
plus all new speaker terminals allowing 4mm banana plugs, and all RCA
sockets need changing. The list of things needing to be done would
fill a couple of screen fulls. No wonder I found I could not earn much
as an audio tech on this type of work for owners loathe to pay a
socially just wage.

But for me, since I took deep interest in audio maters in 1993, it was
about the wonderment rather than the dollars. Because I worked my arse
off when young, I have escaped paying rent, or upkeep of ex-wives etc,
and i could afford change from the building trade to audio trade. Its
no wonder that so few ppl try to fukkabout commercially with tube
amps, but I didn't fancy learning about computers, or fixing
toasters.

Patrick Turner








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