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Default 6J6 driving EL84

Hi RATs!

OK, 6J6 driving 6BQ5 P-P. Using IXYS constant current source under the
shared cathode of the 6J6

Merry Christmas and Happy New Ears!

Al


PS, I may us 5J6 or SV572-10 ...
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John Byrns John Byrns is offline
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Default 6J6 driving EL84

In article
,
tubegarden wrote:

Hi RATs!

OK, 6J6 driving 6BQ5 P-P. Using IXYS constant current source under the
shared cathode of the 6J6

Merry Christmas and Happy New Ears!


What qualities does the 6J6 possess that recommend it for this service
over say an ECC81? I remember when some people considered the 6J6 to be
junk for audio purposes, but times change.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/
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Default 6J6 driving EL84

On Dec 17, 12:05�pm, John Byrns wrote:

What qualities does the 6J6 possess that recommend it for this service
over say an ECC81? �I remember when some people considered the 6J6 to be
junk for audio purposes, but times change.

Regards,

John Byrns

--
Surf my web pages at, �http://fmamradios.com/


Hi John,

I dunno, that is what the poster used. My guess is the shared cathode,
as the circuit brings the signal in on one grid and the parallel grid
is gounded, giving a one stage splitter/driver.

I ignore all comments on audio junk tubes

A few of us get circuits to sound good. Everybody is a "Knowledgeable
Critic". Sigh.

Happy Ears!
Al



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Doug Bannard Doug Bannard is offline
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Default 6J6 driving EL84


"John Byrns" wrote in message
...
In article
,
tubegarden wrote:

Hi RATs!

OK, 6J6 driving 6BQ5 P-P. Using IXYS constant current source under the
shared cathode of the 6J6

Merry Christmas and Happy New Ears!


What qualities does the 6J6 possess that recommend it for this service
over say an ECC81? I remember when some people considered the 6J6 to be
junk for audio purposes, but times change.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/


From looking at the transfer characteristics of both the 6J6 and the ECC81,
I see no overwhelming reason why the 6J6 would be considered to be junk for
audio purposes. The only potential "gotcha" is perhaps the maximum grid
circuit return resistance of 500kohms, but I think that biasing with a CCS
in the common cathode is certainly worth a try as long as the two sections
are well matched at the standing current selected.

As to the qualities that recommend it over an ECC81, price is the one that
jumps out at me. The 6J6 is dirt cheap and many of us probably have quite a
few in our collections (at least 50 new ones in my own collection).

Best Regards : Doug Bannard


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Default 6J6 driving EL84

On Dec 17, 4:21 pm, tubegarden wrote:
Hi RATs!

OK, 6J6 driving 6BQ5 P-P. Using IXYS constant current source


I suppose I could look it up, but we're short of something to discuss
on RAT. So, what is an "IXYS current source"?

under the
shared cathode of the 6J6

Merry Christmas and Happy New Ears!

Al

PS, I may us 5J6 or SV572-10 ...


Now you're speaking in tongues a middle-aged bovver-boy like me can
understand! The SV572-10 is the real heavy metal rocker's amp out of
those Svetlana SV572-xx tubes, the -3 being a vocalist's delight with
one of the best midranges in the business, the -30 sounding pretty
punchy, verging on crude unless you matched it carefully to very
polite speakers, and the -160 being a pentode in drag (dunno what Svet
was thinking of adding it -- maybe some transmitting purpose outside
my ken).

Andre Jute
Perception is a skill that requires study and careful development over
a long period of time. Few have it as a natural gift. -- Iain Churches



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Default 6J6 driving EL84

On Dec 17, 9:10 pm, "Doug Bannard" wrote:
"John Byrns" wrote in message

...



In article
,
tubegarden wrote:


Hi RATs!


OK, 6J6 driving 6BQ5 P-P. Using IXYS constant current source under the
shared cathode of the 6J6


Merry Christmas and Happy New Ears!


What qualities does the 6J6 possess that recommend it for this service
over say an ECC81? I remember when some people considered the 6J6 to be
junk for audio purposes, but times change.


Regards,


John Byrns


--
Surf my web pages at, http://fmamradios.com/


From looking at the transfer characteristics of both the 6J6 and the ECC81,
I see no overwhelming reason why the 6J6 would be considered to be junk for
audio purposes. The only potential "gotcha" is perhaps the maximum grid
circuit return resistance of 500kohms, but I think that biasing with a CCS
in the common cathode is certainly worth a try as long as the two sections
are well matched at the standing current selected.

As to the qualities that recommend it over an ECC81, price is the one that
jumps out at me. The 6J6 is dirt cheap and many of us probably have quite a
few in our collections (at least 50 new ones in my own collection).

Best Regards : Doug Bannard


Perhaps a question of tone not revealed by the transfer curves? The
12AT7, 12AU7 and 12AX7 each has a distinctive tone, for instance.

Andre Jute
A little inaccuracy sometimes saves tons of explanation. --H.H.Munro
("Saki")(1870-1916)



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Default 6J6 driving EL84




Perhaps a question of tone not revealed by the transfer curves? The
12AT7, 12AU7 and 12AX7 each has a distinctive tone, for instance.


Those do have differing curves. And the "tone" will depend on the
circuit the tube is in as well. Swapping one for another will sound
different.
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Default 6J6 driving EL84

On Mon, 17 Dec 2007 14:03:36 -0800 (PST), Andre Jute
wrote:

On Dec 17, 4:21 pm, tubegarden wrote:
Hi RATs!

OK, 6J6 driving 6BQ5 P-P. Using IXYS constant current source


I suppose I could look it up, but we're short of something to discuss
on RAT. So, what is an "IXYS current source"?

http://www.pmillett.com/current_source.htm

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Default 6J6 driving EL84

On Dec 17, 3:03�pm, Andre Jute wrote:


I suppose I could look it up, but we're short of something to discuss
on RAT. So, what is an "IXYS current source"?


Hi RATs!

http://ixdev.ixys.com/DataSheet/98704.pdf

Happy Ears!

Al

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Default 6J6 driving EL84

Al said:

http://ixdev.ixys.com/DataSheet/98704.pdf

Is "9 - 900k" dynamic R OK?

Seems a wide range. Just wondering.

Ian




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Default 6J6 driving EL84


"Ian Iveson" wrote in message . uk...
Al said:

http://ixdev.ixys.com/DataSheet/98704.pdf

Is "9 - 900k" dynamic R OK?

Seems a wide range. Just wondering.

Ian


Sounds like a very good current regulator to me,
capable of a 100:1 dynamic range. You, as the
designer, control how low the dynamic R goes in
your circuit by controlling how low the dynamic
voltage across the device goes during operation
- the lower the instantanious voltage, the lower
the instantanious R required to maintain the
design current.

Fred


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Default 6J6 driving EL84

On Dec 18, 12:54 am, J.P. wrote:
On Mon, 17 Dec 2007 14:03:36 -0800 (PST), Andre Jute

wrote:
On Dec 17, 4:21 pm, tubegarden wrote:
Hi RATs!


OK, 6J6 driving 6BQ5 P-P. Using IXYS constant current source


I suppose I could look it up, but we're short of something to discuss
on RAT. So, what is an "IXYS current source"?


http://www.pmillett.com/current_source.htm


Thanks. Saved. -- AJ
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Default 6J6 driving EL84

On Dec 18, 3:20Â*am, tubegarden wrote:
On Dec 17, 3:03�pm, Andre Jute wrote:



I suppose I could look it up, but we're short of something to discuss
on RAT. So, what is an "IXYS current source"?


Hi RATs!

http://ixdev.ixys.com/DataSheet/98704.pdf

Happy Ears!

Al


Thanks. Of course, since the regulator is drawn as one block, some
benighted person will argue that you are using ***silicon^&*()$£@! in
the signal path...

Andre Jute
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Default 6J6 driving EL84

In article
,
Andre Jute wrote:

On Dec 18, 3:20Â*am, tubegarden wrote:
On Dec 17, 3:03?pm, Andre Jute wrote:

I suppose I could look it up, but we're short of something to discuss
on RAT. So, what is an "IXYS current source"?


Hi RATs!

http://ixdev.ixys.com/DataSheet/98704.pdf

Happy Ears!

Al


Thanks. Of course, since the regulator is drawn as one block, some
benighted person will argue that you are using ***silicon^&*()$£@! in
the signal path...


Isn't he?


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/
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Default 6J6 driving EL84



John Byrns wrote:

In article
,
tubegarden wrote:

Hi RATs!

OK, 6J6 driving 6BQ5 P-P. Using IXYS constant current source under the
shared cathode of the 6J6

Merry Christmas and Happy New Ears!


What qualities does the 6J6 possess that recommend it for this service
over say an ECC81? I remember when some people considered the 6J6 to be
junk for audio purposes, but times change.


6J6 is OK for the app considered in the LTP driver for EL84.

But it can be microphonic. I had a few smaples that were terrible in a
phono stage where
I thought they'd be just great because like the 12AT7/ECC81, the GM is
high so input noise would be low.

Patrick Turner.

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/



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Default Are all pigs...er... CCL positions equal? was 6J6 driving EL84

On Dec 19, 12:17 am, John Byrns wrote:
In article
,
Andre Jute wrote:



On Dec 18, 3:20 am, tubegarden wrote:
On Dec 17, 3:03?pm, Andre Jute wrote:


I suppose I could look it up, but we're short of something to discuss
on RAT. So, what is an "IXYS current source"?


Hi RATs!


http://ixdev.ixys.com/DataSheet/98704.pdf


Happy Ears!


Al


Thanks. Of course, since the regulator is drawn as one block, some
benighted person will argue that you are using ***silicon^&*()$£@! in
the signal path...


Isn't he?

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/


Okay, the ultrafidelista, and others, say loosely that every component
can be heard. But some can be heard more or less than others because
of one or more of the intrinsic qualities of the component, the
relative quality of its manufacture or materials, and its relative
position in the circuit. It is this last factor, relative position in
circuit we want to discuss. A notorious case is the load capacitor in
parallel shunt feed SE output topologies, aka parafeed. (Abstracting
for the moment whether the ungapped trx or the cap is relatively more
to blame for any solecism in the sound.)

Notice that I distinguish in the headline between a constant current
load (CCL), which operates in the plate circuit, and a constant
current source (CCS), which operates in the tail of the tube.

It seems to me that the CCL might be a little more blameless, in that
the signal takes a right turn to either the next tube or the output
transformer before it reaches the CCL. It also seems to me that the
grunge of CCS silicon might enter the signal circuit via the ground
line without first being attenuated by the triode's inherent NFB.
Those are certainly impressive attenuations that Pete Millett
measured.

Of course, any or this will become a consideration only if the
residual noise of the silicon alters the quality of the noise as well
as the amount, which might come down to a fine psycho-acoustic
judgement; if there is no observable difference either by meter or by
psychological test, then we could just accept the noise reduction as A
Good Thing.

I'm too old to worry about whether silicon is bad on principle just
because some uncouth obsessive I have never heard of says so.

Andre Jute
Neutrinos seek positrinos to party with
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Default Are all pigs...er... CCL positions equal? was 6J6 driving EL84

In article
,
Andre Jute wrote:

On Dec 19, 12:17 am, John Byrns wrote:
In article
,
Andre Jute wrote:



On Dec 18, 3:20 am, tubegarden wrote:
On Dec 17, 3:03?pm, Andre Jute wrote:


I suppose I could look it up, but we're short of something to discuss
on RAT. So, what is an "IXYS current source"?


Hi RATs!


http://ixdev.ixys.com/DataSheet/98704.pdf


Happy Ears!


Al


Thanks. Of course, since the regulator is drawn as one block, some
benighted person will argue that you are using ***silicon^&*()$£@! in
the signal path...


Isn't he?


Okay, the ultrafidelista, and others, say loosely that every component
can be heard. But some can be heard more or less than others because
of one or more of the intrinsic qualities of the component, the
relative quality of its manufacture or materials, and its relative
position in the circuit. It is this last factor, relative position in
circuit we want to discuss. A notorious case is the load capacitor in
parallel shunt feed SE output topologies, aka parafeed. (Abstracting
for the moment whether the ungapped trx or the cap is relatively more
to blame for any solecism in the sound.)

Notice that I distinguish in the headline between a constant current
load (CCL), which operates in the plate circuit, and a constant
current source (CCS), which operates in the tail of the tube.

It seems to me that the CCL might be a little more blameless, in that
the signal takes a right turn to either the next tube or the output
transformer before it reaches the CCL. It also seems to me that the
grunge of CCS silicon might enter the signal circuit via the ground
line without first being attenuated by the triode's inherent NFB.
Those are certainly impressive attenuations that Pete Millett
measured.

Of course, any or this will become a consideration only if the
residual noise of the silicon alters the quality of the noise as well
as the amount, which might come down to a fine psycho-acoustic
judgement; if there is no observable difference either by meter or by
psychological test, then we could just accept the noise reduction as A
Good Thing.

I'm too old to worry about whether silicon is bad on principle just
because some uncouth obsessive I have never heard of says so.


Andre, you are talking like you have lost it and gone over to the dark
side, like Arnie and that guy who worked at the Scottish bank whose name
escapes me. Next you will be regaling us with all the gory details on
your latest solid state amplifier designs.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/
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Default 6J6 driving EL84

Thanks Fred

Sounds like a very good current regulator to me,
capable of a 100:1 dynamic range. You, as the
designer, control how low the dynamic R goes in
your circuit by controlling how low the dynamic
voltage across the device goes during operation
- the lower the instantanious voltage, the lower
the instantanious R required to maintain the
design current.


The same would be true of a resistor. The greater the
voltage you have to play with, the greater you can make the
resistance for a given required current.

I hadn't read far enough into the datasheet to see under
what circumstances that dynamic R might vary, so thanks for
the info.

But is 100k OK? Fine if it were a resistor in most cases,
IMO, and for most ppl maybe fine even for a non-linear
device. But I would bet that some would argue that 100k is
not great enough to guarantee that the sound of silicon
can't seep in under the back door.

OTOH, I have seen many claims that simple discreet silicon
circuits achieve many Megohms, but with no mention of
frequency response, as if it didn't exist or didn't matter.

If the ixys device achieves 100k at all frequencies of
interest, it's just about good enough, IMHO. It's certainly
convenient.

cheers, Ian


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Default 6J6 driving EL84


"Ian Iveson" wrote in message news
Thanks Fred

Sounds like a very good current regulator to me,
capable of a 100:1 dynamic range. You, as the
designer, control how low the dynamic R goes in
your circuit by controlling how low the dynamic
voltage across the device goes during operation
- the lower the instantanious voltage, the lower
the instantanious R required to maintain the
design current.


The same would be true of a resistor. The greater the voltage you have to play with, the greater you can make the resistance for a
given required current.

I hadn't read far enough into the datasheet to see under what circumstances that dynamic R might vary, so thanks for the info.

But is 100k OK? Fine if it were a resistor in most cases, IMO, and for most ppl maybe fine even for a non-linear device. But I
would bet that some would argue that 100k is not great enough to guarantee that the sound of silicon can't seep in under the back
door.

OTOH, I have seen many claims that simple discreet silicon circuits achieve many Megohms, but with no mention of frequency
response, as if it didn't exist or didn't matter.

If the ixys device achieves 100k at all frequencies of interest, it's just about good enough, IMHO. It's certainly convenient.

cheers, Ian


The IXYS device achieves many megohms at all frequencies
of interest, Ian, unless your only frequency of interest is 0 Hz.
It's a current regulator, not a solid state resistor.

The AC resistance, or impedance, of a current regulator
is in the megohms because the current through it doesn't
change when the voltage across it changes - it looks like an
open circuit in that respect. But it does conduct a (fixed by
the designer) DC current, so depending on the voltage across
it at any given moment, one can calculate a DC resistance for
that moment by ohm's law. But it still looks like an open circuit
to an AC voltage because, again, the changing voltage fails to
cause a changing current as it would in a resistance.

DC resistance calculations have about as much bearing
on current regulator performance as they do on output
transformer performance, only less.

This isn't rocket science, Ian, and you don't need calculus to
understand it. It's covered in any modern electronics text.

Fred


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Default 6J6 driving EL84


"Fred" wrote in message
...

"Ian Iveson" wrote in
message
news
Thanks Fred

Sounds like a very good current regulator to me,
capable of a 100:1 dynamic range. You, as the
designer, control how low the dynamic R goes in
your circuit by controlling how low the dynamic
voltage across the device goes during operation
- the lower the instantanious voltage, the lower
the instantanious R required to maintain the
design current.


The same would be true of a resistor. The greater the
voltage you have to play with, the greater you can make
the resistance for a given required current.

I hadn't read far enough into the datasheet to see under
what circumstances that dynamic R might vary, so thanks
for the info.

But is 100k OK? Fine if it were a resistor in most cases,
IMO, and for most ppl maybe fine even for a non-linear
device. But I would bet that some would argue that 100k
is not great enough to guarantee that the sound of
silicon can't seep in under the back door.

OTOH, I have seen many claims that simple discreet
silicon circuits achieve many Megohms, but with no
mention of frequency response, as if it didn't exist or
didn't matter.

If the ixys device achieves 100k at all frequencies of
interest, it's just about good enough, IMHO. It's
certainly convenient.

cheers, Ian


The IXYS device achieves many megohms at all frequencies
of interest, Ian, unless your only frequency of interest
is 0 Hz.
It's a current regulator, not a solid state resistor.

The AC resistance, or impedance, of a current regulator
is in the megohms because the current through it doesn't
change when the voltage across it changes - it looks like
an
open circuit in that respect. But it does conduct a
(fixed by
the designer) DC current, so depending on the voltage
across
it at any given moment, one can calculate a DC resistance
for
that moment by ohm's law. But it still looks like an open
circuit
to an AC voltage because, again, the changing voltage
fails to
cause a changing current as it would in a resistance.

DC resistance calculations have about as much bearing
on current regulator performance as they do on output
transformer performance, only less.

This isn't rocket science, Ian, and you don't need
calculus to
understand it. It's covered in any modern electronics
text.


All of which appears to me as a total nonsequitur in toto,
and pure nonsense in parts.

You won't find understanding in books, particularly if you
have difficulty reading. You need to think a bit too.

I took it that "dynamic R" meant the dynamic resistance of
the current source. Since it is given as 100k max, and that
is very different from your "many megohms", I felt it worth
discussion. I may be mistaken, but you have failed to spot
where my mistake is, smart-arse.

And you are wrong, but I can't now be arsed to tell you
where.

bye, Ian




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Default 6J6 driving EL84

Hi RATs!

The amp design in question has one happy listener. I don't know if he
is a Supreme Sonic Purist or anything - he posts about amps he builds
that he likes

The signal path is an oversimplification of the system to help
relatively unschooled people fix up really dead amps.

And there are stickers and knick-knacks you can put on or around stuff
to fix up really dead aural imaginations.

The IXYS is a sub-$2. part that makes the circuit sound better. For
one guy. I like to try stuff that made someone happy. I can't remember
what every circuit sounded like, but, I can always enjoy trying
another one, even if it sometimes takes a year or three ... so many
lovely ladies of the mind, so little time.

The endless bickering on this Newsgroup has many functions, and many
posters have none, apparently, only a great need to give voice to
their hostilities.

It is OK, no one who wants to try strange and exotic stuff and listen
cares what anybody else needs ... Well, unless she insists on getting
her dreams to come true right now My wife has been very sick many
more years than me, her dreams are of cigarettes and yogurt. Sigh.

So, is using a 6J6 with the signal going in on one grid and the other
grid grounded really what a long tail pair is? The signals on the
plates are both pumped up and out of phase. Wow!

One of the great things about dragging one's unschooled brain through
engineering texts is the wonderful ability of technical authors to
hide so much useful information.

It has kept me busy for years, looking for someone who can simply
describe a circuit through which they enjoy listening to music.

It happens, but, there are so many people eagar to share their command
of the latest techno-gibberish, it ain't often. And even I often get
enthusiastic talking about what fun changing a part was ...

If any of you have not built a single tube amp, get busy. What you
hear when there is nothing else there will be a wonderful learning
experience SV-83 and 417A each do quite well, alone And for
those of you who need to explain why that is a waste of time, money
and effort in all the very best techno-garble, Merry Christmas!

Happy Ears!
Al





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Default Are all pigs...er... CCL positions equal? was 6J6 drivingEL84

John Byrns wrote:,
Andre Jute wrote:
I'm too old to worry about whether silicon is bad on principle just
because some uncouth obsessive I have never heard of says so.


Andre, you are talking like you have lost it and gone over to the dark
side, like Arnie and that guy who worked at the Scottish bank whose name
escapes me.


Here's a tip: his one distinction in life is that he is the world's
greatest SPAM merchant, absolutely tons of it.

Next you will be regaling us with all the gory details on
your latest solid state amplifier designs.


Since you ask, I am just sitting here wondering whether I should
resurrect my notorious Christmas Pipes (named by RdM) and play
Gregorian Chant with *extra ambience*, or stick with Bach Cantata, of
which I have a book of 250 discs lying open beside me (1), enough to
carry me through to St Stephen's Day. If I decide on the Gregorian
Chant, for an amp I'll use my miniGainBrick Zip LM675, which is
described at:
http://members.lycos.co.uk/fiultra/K...dre%20Jute.htm
--developed to Class A in an attempt to mimic triode sound at:
http://members.lycos.co.uk/fiultra/K...dre%20Jute.htm
--with the schematic at:
http://members.lycos.co.uk/fiultra/K...20mGBschem.jpg
--and the component layout at:
http://members.lycos.co.uk/fiultra/K...%20mGBmatr.jpg
--and finally a piccie at:
http://members.lycos.co.uk/fiultra/K...%20NoBleed.jpg
(actually the pic shows why you shouldn't stick your fingers into even
silicon amps...)

It will probably need a rebuild because it has been sitting around for
a year or two in my studio with the signal section PCB bolted to the
outside of the power supply and is no doubt damaged. If I rebuild it,
I'll also rename it The Pinkie Sound, in remembrance of it being built
while I was waited for Pinkie to design his silicon amp that would
sound like 300B that time the poor bugger challenged me to a design
contest.

Andre Jute

(1) I used to keep my CDs standing on end in precisely right-size
cardboard boxes (US: cartons) that supermarkets get their vegetables
and fruit delivered in, with lips and indents for stacking. But
250-300 CDs per box weigh a lot when they are stacked to the ceiling
and you want a disc from the bottommost box. Woulda been even heavier
if I ever got around to making the wooden boxes I intended... Then I
saw big books of CD disc pockets at a department store and bought
their entire stock for a few hundred euro. The books each have enough
pockets to hold up to 250 discs, booklets, and so on. A full book
takes up only three inches of bookshelf space and, while heavy, is
nowhere near as heavy as a big box full of CD disc cases and
extraneous paperwork, nor as awkward to handle. At about seven or
eight feet of shelf space for my disc collection, that's a big space
saving and solves the handling problem tidily, or will as soon as I
reinforce the shelves of the bookshelf I want to use...

Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review



  #23   Report Post  
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Andre Jute Andre Jute is offline
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Default 6J6 driving EL84

On Dec 19, 10:43 am, tubegarden wrote:
Hi RATs!

The amp design in question has one happy listener. I don't know if he
is a Supreme Sonic Purist or anything - he posts about amps he builds
that he likes

If any of you have not built a single tube amp, get busy. What you
hear when there is nothing else there will be a wonderful learning
experience SV-83 and 417A each do quite well, alone


If you choose the 417A, to save you time, here is my Type 68bis "MZ"
417A one-tube amp:
http://members.lycos.co.uk/fiultra/K...0T68MZ417A.jpg
Here is the circuit with component list:
http://members.lycos.co.uk/fiultra/t...17acircuit.jpg
And here is the layout:
http://members.lycos.co.uk/fiultra/t68bismzlayout.jpg
Suitable speakers are shown with the photographs referenced above;
other high-sensitivity speakers I designed for this and other low-
output amps are available from
http://members.lycos.co.uk/fiultra/JUTE%20ON%20AMPS.htm
The High Wife Acceptance Factor (HWAF) horn:
http://members.lycos.co.uk/fiultra/K...20T91HWAF3.jpg
is authoritative but pricey with Lowthers; ask Mick about Fostex
equivalents. The Impresario, with its guitar driver, is inexpensive
and easy to build and surprisingly articulate for the money:
http://members.lycos.co.uk/fiultra/K...Impresario.jpg

And for
those of you who need to explain why that is a waste of time, money
and effort in all the very best techno-garble, Merry Christmas!


It could be worse. Imagine what one of those technogobblegabble guys
would taste like as a turkey...

Happy Ears!
Al


Andre Jute
A public service on legs
  #24   Report Post  
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Fred[_8_] Fred[_8_] is offline
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Default 6J6 driving EL84


"Ian Iveson" wrote in message k...

"Fred" wrote in message ...

"Ian Iveson" wrote in message news
Thanks Fred

Sounds like a very good current regulator to me,
capable of a 100:1 dynamic range. You, as the
designer, control how low the dynamic R goes in
your circuit by controlling how low the dynamic
voltage across the device goes during operation
- the lower the instantanious voltage, the lower
the instantanious R required to maintain the
design current.

The same would be true of a resistor. The greater the voltage you have to play with, the greater you can make the resistance for
a given required current.

I hadn't read far enough into the datasheet to see under what circumstances that dynamic R might vary, so thanks for the info.

But is 100k OK? Fine if it were a resistor in most cases, IMO, and for most ppl maybe fine even for a non-linear device. But I
would bet that some would argue that 100k is not great enough to guarantee that the sound of silicon can't seep in under the
back door.

OTOH, I have seen many claims that simple discreet silicon circuits achieve many Megohms, but with no mention of frequency
response, as if it didn't exist or didn't matter.

If the ixys device achieves 100k at all frequencies of interest, it's just about good enough, IMHO. It's certainly convenient.

cheers, Ian


The IXYS device achieves many megohms at all frequencies
of interest, Ian, unless your only frequency of interest is 0 Hz.
It's a current regulator, not a solid state resistor.

The AC resistance, or impedance, of a current regulator
is in the megohms because the current through it doesn't
change when the voltage across it changes - it looks like an
open circuit in that respect. But it does conduct a (fixed by
the designer) DC current, so depending on the voltage across
it at any given moment, one can calculate a DC resistance for
that moment by ohm's law. But it still looks like an open circuit
to an AC voltage because, again, the changing voltage fails to
cause a changing current as it would in a resistance.

DC resistance calculations have about as much bearing
on current regulator performance as they do on output
transformer performance, only less.

This isn't rocket science, Ian, and you don't need calculus to
understand it. It's covered in any modern electronics text.


All of which appears to me as a total nonsequitur in toto, and pure nonsense in parts.

You won't find understanding in books, particularly if you have difficulty reading. You need to think a bit too.

I took it that "dynamic R" meant the dynamic resistance of the current source. Since it is given as 100k max, and that is very
different from your "many megohms", I felt it worth discussion. I may be mistaken, but you have failed to spot where my mistake
is, smart-arse.

And you are wrong, but I can't now be arsed to tell you where.


Final words of wisdom from someone without a clue. Let us
know if you figure it out.

Fred

bye, Ian



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John Byrns John Byrns is offline
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Default Are all pigs...er... CCL positions equal? was 6J6 driving EL84

In article
,
Andre Jute wrote:

Since you ask, I am just sitting here wondering whether I should
resurrect my notorious Christmas Pipes (named by RdM) and play
Gregorian Chant with *extra ambience*,


Yes, go for it.

(1) I used to keep my CDs standing on end in precisely right-size
cardboard boxes (US: cartons) that supermarkets get their vegetables
and fruit delivered in, with lips and indents for stacking. But
250-300 CDs per box weigh a lot when they are stacked to the ceiling
and you want a disc from the bottommost box. Woulda been even heavier
if I ever got around to making the wooden boxes I intended... Then I
saw big books of CD disc pockets at a department store and bought
their entire stock for a few hundred euro. The books each have enough
pockets to hold up to 250 discs, booklets, and so on. A full book
takes up only three inches of bookshelf space and, while heavy, is
nowhere near as heavy as a big box full of CD disc cases and
extraneous paperwork, nor as awkward to handle.


How on earth do they fit 250 CDs & booklets in a book only 3 inches
thick? Assuming the book is 2 CDs deep and three high, a pretty large
book, that would be 40 CDs thick, or nearly 14 CDs per inch, which seems
a bit much when considering that the book needs covers and internal
pockets for the CDs.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/


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Ian Iveson Ian Iveson is offline
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Posts: 960
Default 6J6 driving EL84

snip interesting stuff...

What voltage have you got across the source, Al, and what
value current-sensing resistor?

There is no timing info on the datasheet.

cheers, Ian


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tubegarden tubegarden is offline
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Default 6J6 driving EL84

On Dec 19, 6:48�pm, "Ian Iveson"
wrote:
snip interesting stuff...

What voltage have you got across the source, Al, and what
value current-sensing resistor?

There is no timing info on the datasheet.

cheers, Ian


Hi RATs!

I haven't got the parts yet. The schematic just says IXYS at -66V with
the current through the shared cathode set at 8 mA.

I assume I will use my fabulous trial and measure to get similar
values.

Meanwhile, I stumbled upon a 6528 SE

What a tube! Too bad Aunty Klectron Sply doest even list it anymore :
( I only have two, TungSol.

Happy Ears!
Al






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