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Patrick Turner
Guest
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 Posted:
Mon Jul 25, 2005 9:28 pm Post subject:
The man wants to make a 212 SET amp. |
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Anyone have any experience in using the 212 triode
for an SET amp?
I have been asked for some input to a project a man
is about to embark on; he has the tubes, but
needs a little help.
Patrick Turner
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Patrick Turner
Guest
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| Posted:
Mon Jul 25, 2005 11:20 pm Post subject:
Re: The man wants to make a 212 SET amp. |
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It seems its a 212E, or 4212E.
I found a reference to Kronzilla at
http://www.enjoythemusic.com/magazine/equipment/0503/kraudiokronzilla.htm
But no details of loads, although Kronzilla boasts
42 watts at 5% thd from a pair of paralleled tubes.
This suggests class A1, and a low B+, and very conservative op
conditions.
I found the data on the 212E and ONE could be set up for
class A2 and at 1.3kV, 140mA, Pda = 182 watts, 11.2k RL, and 54 watts is
available,
with 28 watts in class A1.
Drive voltage in A2 would be about 56Vrms to G1 biased at -50V.
Ra is 2,500 ohms, so DF isn't too bad.
Another question, is WE making the WE212E again or not?
Patrick Turner.
Patrick Turner wrote:
| Quote: | Anyone have any experience in using the 212 triode
for an SET amp?
I have been asked for some input to a project a man
is about to embark on; he has the tubes, but
needs a little help.
Patrick Turner |
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John Stewart
Guest
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| Posted:
Mon Jul 25, 2005 11:40 pm Post subject:
Re: The man wants to make a 212 SET amp. |
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Patrick Turner wrote:
| Quote: | Anyone have any experience in using the 212 triode
for an SET amp?
I have been asked for some input to a project a man
is about to embark on; he has the tubes, but
needs a little help.
Patrick Turner
|
See WE data at
http://frank.pocnet.net/sheets/136/2/212E.pdf
JLS |
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Adam Stouffer
Guest
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| Posted:
Tue Jul 26, 2005 2:41 am Post subject:
Re: The man wants to make a 212 SET amp. |
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Patrick Turner wrote:
| Quote: | Anyone have any experience in using the 212 triode
for an SET amp?
I have been asked for some input to a project a man
is about to embark on; he has the tubes, but
needs a little help.
Patrick Turner
|
Theres a yahoo group or two devoted to the 212. The message archives for
the GM70 group has a lot of threads about it.
A few people agreed that the 212 was powerful but still didn't sound as
nice as smaller triodes like the 211 or 845.
Adam |
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Patrick Turner
Guest
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| Posted:
Tue Jul 26, 2005 4:45 am Post subject:
Re: The man wants to make a 212 SET amp. |
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John Stewart wrote:
| Quote: | Patrick Turner wrote:
Anyone have any experience in using the 212 triode
for an SET amp?
I have been asked for some input to a project a man
is about to embark on; he has the tubes, but
needs a little help.
Patrick Turner
See WE data at
http://frank.pocnet.net/sheets/136/2/212E.pdf
JLS
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Thanks John, I found all that last night in my searches.
I was wondering if anyone here had actually had real expereince with
the 212E.
Its not used commonly, but it looks like a good candidate for high SET
power.
A guy may need me to wind 4 output trannies for a batch of amps, and as
usual,
he hasn't the foggiest notion of what is required for the OPT,
and nor has the the guy in NZ who is doing the chassis for him.
You can't buy 212E OPTs off the shelf, anywhere.
Patrick Turner. |
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Patrick Turner
Guest
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| Posted:
Tue Jul 26, 2005 4:45 am Post subject:
Re: The man wants to make a 212 SET amp. |
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Adam Stouffer wrote:
| Quote: | Patrick Turner wrote:
Anyone have any experience in using the 212 triode
for an SET amp?
I have been asked for some input to a project a man
is about to embark on; he has the tubes, but
needs a little help.
Patrick Turner
Theres a yahoo group or two devoted to the 212. The message archives for
the GM70 group has a lot of threads about it.
A few people agreed that the 212 was powerful but still didn't sound as
nice as smaller triodes like the 211 or 845.
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Maybe, but did they know to to use it?
The curves indicate it will have excellent performance technically at least.
The only bother is the A2 operation, but only if its set up
for A2.
A2 doesn't have to be used, although if it is, there is a lot more power
than A1.
With A1 a high B+ is needed, perhaps 1,600V, Ia = about 120mA and a high RL
of about 14k, to get a wide linear V swing without the negative going anode
swing
extending past the Ra line for Eg = 0V, ie, when Ea = about 500V on the load
line.
For A2, the B+ can be lower, Ia higher, and RL value at 11k, since the
negative going anode swing
can extend down to Ea = 220V.
To use such tubes optimally, you have to throw lots of voltage, lots of RL
ohms, lots of turns, lots of iron at the tube.
We live in low impedance times, and there is a reluctance to use high
voltage, ohms, turns or iron.
I have to make the OPTs able to have varying impedance connections,
and with ability for use with perhaps other tubes, and maybe also set up in
a tank
of oil, and well sealed, so these OPTs are not child's play to get right.
But we do have terrific iron now days.......
All this may lead me to thouroughly spoil my springtime
by having to wind OPTs for such tubes.
Patrick Turner.
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Fabio Berutti
Guest
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| Posted:
Tue Jul 26, 2005 2:17 pm Post subject:
Re: The man wants to make a 212 SET amp. |
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See the GEC book "Audio frequency amplifier design", chapter 8. It deals
extensively with the use of the GEC V1505, aka 4212, unfortunately only in
push-pull, but transforming one of these circuits in SE is as easy as
"cutting" the drawing between the "push" and the "pull" part. Some data are
provided too.
There's a schematic at http://www10.big.or.jp/~dh/work/0402.html , but I'm
sure I saw the project of a guy who made a monster SE using some STC 4212
tubes
Ciao
Fabio
"Patrick Turner" <info@turneraudio.com.au> ha scritto nel messaggio
news:42E51286.B352AD41@turneraudio.com.au...
| Quote: | Anyone have any experience in using the 212 triode
for an SET amp?
I have been asked for some input to a project a man
is about to embark on; he has the tubes, but
needs a little help.
Patrick Turner
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bill ramsay
Guest
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| Posted:
Tue Jul 26, 2005 3:20 pm Post subject:
Re: The man wants to make a 212 SET amp. |
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On Mon, 25 Jul 2005 16:28:16 GMT, Patrick Turner
<info@turneraudio.com.au> wrote:
| Quote: | Anyone have any experience in using the 212 triode
for an SET amp?
I have been asked for some input to a project a man
is about to embark on; he has the tubes, but
needs a little help.
Patrick Turner
|
Patrick,
I don't know if this is much use, but at http://audiobizarro.com/ you
can see a couple of photographs of amps created with the 212E, the
first is on three chassis, whilst the second, is on more reasonable
one.
I seem to remembe seeing diagrams of these, but the site has changed
somewhat and they have dissapeared/
watch your fingers.
bill |
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John Stewart
Guest
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| Posted:
Tue Jul 26, 2005 3:59 pm Post subject:
Re: The man wants to make a 212 SET amp. |
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Patrick Turner wrote:
| Quote: | John Stewart wrote:
Patrick Turner wrote:
Anyone have any experience in using the 212 triode
for an SET amp?
I have been asked for some input to a project a man
is about to embark on; he has the tubes, but
needs a little help.
Patrick Turner
See WE data at
http://frank.pocnet.net/sheets/136/2/212E.pdf
JLS
Thanks John, I found all that last night in my searches.
I was wondering if anyone here had actually had real expereince with
the 212E.
Its not used commonly, but it looks like a good candidate for high SET
power.
A guy may need me to wind 4 output trannies for a batch of amps, and as
usual,
he hasn't the foggiest notion of what is required for the OPT,
and nor has the the guy in NZ who is doing the chassis for him.
You can't buy 212E OPTs off the shelf, anywhere.
Patrick Turner.
|
Should be an interesting project.
But get your money for the transformers up front!! Since your prospective
client seems somewhat less than experienced, he could become frustrated &
may lose interest partway thru.
I found the 2nd paragraph under Class A operation on the WE212E data sheet
interesting. It sounds as though local spot heating is a potential problem
on the anode. OK I guess at lower voltages.
Cheers, John Stewart |
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Patrick Turner
Guest
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| Posted:
Tue Jul 26, 2005 5:20 pm Post subject:
Re: The man wants to make a 212 SET amp. |
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Fabio Berutti wrote:
| Quote: | See the GEC book "Audio frequency amplifier design", chapter 8. It deals
extensively with the use of the GEC V1505, aka 4212, unfortunately only in
push-pull, but transforming one of these circuits in SE is as easy as
"cutting" the drawing between the "push" and the "pull" part. Some data are
provided too.
There's a schematic at http://www10.big.or.jp/~dh/work/0402.html , but I'm
sure I saw the project of a guy who made a monster SE using some STC 4212
tubes
Ciao
|
So the 4212, or 212E is the same tube as the V1505?
I have the GE book with 17 schematics from 5 to 1,100 watts, with two V1505 used
for the 1,100 watt amp.
Such an amp was used for all the horns in a stadium. I used to think showground
PA systems
sounded dreadful when i was a lad.
Its not quite all that easy to cut a class B amp in 1/2 and get a class A SE
amp.
One still needs to work from first principles.
The url you gave has a PP amp with 1,100V applied to the CT and cathode biasing,
so it must be a largely class A1 PP amp.
The IST input tranny is 150 ohms :100kohms, with the 150 ohm
input primary fed from a 1.5 watt 100 ohm pot to set the level.
so the turn ratio is 1:25.8, so for 100vrms grid to grid max drive, you need
to apply 3.9vrms to the input tranny, which is doable
with a small power amp.
The stray C and miller C would limit the F response somewhat
since the secondary impedance is 100k, getting rather high.
Patrick Turner. |
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Patrick Turner
Guest
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| Posted:
Tue Jul 26, 2005 5:26 pm Post subject:
Re: The man wants to make a 212 SET amp. |
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bill ramsay wrote:
| Quote: | On Mon, 25 Jul 2005 16:28:16 GMT, Patrick Turner
info@turneraudio.com.au> wrote:
Anyone have any experience in using the 212 triode
for an SET amp?
I have been asked for some input to a project a man
is about to embark on; he has the tubes, but
needs a little help.
Patrick Turner
Patrick,
I don't know if this is much use, but at http://audiobizarro.com/ you
can see a couple of photographs of amps created with the 212E, the
first is on three chassis, whilst the second, is on more reasonable
one.
|
You mean
http://audiobizarro.com/billeci5.jpg
yes, but no schematics.
Patrick Turner.
| Quote: |
I seem to remembe seeing diagrams of these, but the site has changed
somewhat and they have dissapeared/
watch your fingers.
bill
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Patrick Turner
Guest
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| Posted:
Tue Jul 26, 2005 5:53 pm Post subject:
Re: The man wants to make a 212 SET amp. |
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John Stewart wrote:
| Quote: | Patrick Turner wrote:
John Stewart wrote:
Patrick Turner wrote:
Anyone have any experience in using the 212 triode
for an SET amp?
I have been asked for some input to a project a man
is about to embark on; he has the tubes, but
needs a little help.
Patrick Turner
See WE data at
http://frank.pocnet.net/sheets/136/2/212E.pdf
JLS
Thanks John, I found all that last night in my searches.
I was wondering if anyone here had actually had real expereince with
the 212E.
Its not used commonly, but it looks like a good candidate for high SET
power.
A guy may need me to wind 4 output trannies for a batch of amps, and as
usual,
he hasn't the foggiest notion of what is required for the OPT,
and nor has the the guy in NZ who is doing the chassis for him.
You can't buy 212E OPTs off the shelf, anywhere.
Patrick Turner.
Should be an interesting project.
But get your money for the transformers up front!! Since your prospective
client seems somewhat less than experienced, he could become frustrated &
may lose interest partway thru.
|
I warn them of the delay that is normal for when anything quite exotic
is ordered that isn't what is probably available froma shelf in a shop
somewhere
in Japan.
I never start a project like this without at least 50% of the payment.
If they lose interest, or die from some ailment during the 3 mths I may
take to complete works in hand and do their items, and they don't complete
the deal, then I am at least paid for my material and some labour.
I normally give late completers of deals a long time to get their pennys
together and pay me.
Its normal for me to have up to six or seven items that i have repaired within
two weeks
of item reciept, but which sit around here for months before pick up.
I wait a year, and if i don't hear from them I may sell the items, and usually
I don't get
the price agreed on the original contract; OPTs like these may well suit
builders of other
high powered SET amps using multiple low power tubes or large transmitter
tubes,
so hence i'd never build such an item without having several impedance ratios
available,
including the ability to parallel 2 halves of the primary, so multiple small
tubes could be used.
The design of a 10k:5 OPT can thus be made to suit 2.5k:5.
| Quote: |
I found the 2nd paragraph under Class A operation on the WE212E data sheet
interesting. It sounds as though local spot heating is a potential problem
on the anode. OK I guess at lower voltages.
|
I'd never run such tubes anywhere near their rated max Pd, when hot spots are
very likely.
Pda = about 150watts would be about max practical, and typical class A1
efficiency is 20% with low B+, so you get only 30 watts, about 4% thd.
Class A2 is better, perhaps efficiency is 40%, so 60 watts max but with a lot
more thd at 60 watts, about 8%.
But from the plate curves, the first 20 watts of A1 would be very good with
maybe 2%.
2 watts would about 0.6%, all 2H.
The thd at 2 watts could be about halved if RL is allowed to be high,
so probably thd would then never exceed 0.3% in normal use.
2 watts from an EL34 or 300B would have a lot more thd.
To avoid feedback, you have to throw a lotta glass, iron, copper, turns,
volts,
and ohms at the problem but its no worse than
a rich man spending 10 million on carbon fibre for a yacht to break the
Sydney to Hobart race record, or a cyclist also spending his life's savings on
a
carbon fibre bike frame to be able to pedal up a hill faster.
We only borrow the iron and copper and glass for awhile.
In 100 years maybe it has become something else, but I do not know what
becomes of a carbon fibre yacht.
Patrick Turner.
| Quote: |
Cheers, John Stewart |
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Fabio Berutti
Guest
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| Posted:
Tue Jul 26, 2005 7:03 pm Post subject:
Re: The man wants to make a 212 SET amp. |
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"Patrick Turner" <info@turneraudio.com.au> ha scritto nel messaggio
news:42E629F9.E13EFE09@turneraudio.com.au...
| Quote: |
Fabio Berutti wrote:
See the GEC book "Audio frequency amplifier design", chapter 8. It deals
extensively with the use of the GEC V1505, aka 4212, unfortunately only
in
push-pull, but transforming one of these circuits in SE is as easy as
"cutting" the drawing between the "push" and the "pull" part. Some data
are
provided too.
There's a schematic at http://www10.big.or.jp/~dh/work/0402.html , but
I'm
sure I saw the project of a guy who made a monster SE using some STC 4212
tubes
Ciao
So the 4212, or 212E is the same tube as the V1505?
|
AFAIK it is indeed so.
| Quote: |
I have the GE book with 17 schematics from 5 to 1,100 watts, with two
V1505 used
for the 1,100 watt amp.
|
They're used to get anything in between 400 (most A1 class) and 1100W (AB2
class), varying B+ and driving circuit
| Quote: | Such an amp was used for all the horns in a stadium. I used to think
showground
PA systems
sounded dreadful when i was a lad.
|
Maybe the OPTs were on the cheap side (only speech bandwidth required) and
surely the HORNS were definitely NOT HiFi... would You place an Altec box
costing M$ on the top of a pole and then expose it to an Aussie thunderstorm
(or to the outrages of diarrhoic flying foxes)?
| Quote: |
Its not quite all that easy to cut a class B amp in 1/2 and get a class A
SE
amp.
One still needs to work from first principles.
|
I just meant to "take inspiration" from the circuit, using the idea of
having a KT66 (ok a 6550 is easier to find) cathode-coupled thru a
transformer to the monster triode in order to have a suitably low driver
impedance.
Changing to SE is straightforward, as far as I can understand, and surely an
experienced technician as You will have no problems when re-working the most
suitable operating points. I like very much that GEC book, it really seems
written by true professionals.
| Quote: |
The url you gave has a PP amp with 1,100V applied to the CT and cathode
biasing,
so it must be a largely class A1 PP amp.
The IST input tranny is 150 ohms :100kohms, with the 150 ohm
input primary fed from a 1.5 watt 100 ohm pot to set the level.
so the turn ratio is 1:25.8, so for 100vrms grid to grid max drive, you
need
to apply 3.9vrms to the input tranny, which is doable
with a small power amp.
The stray C and miller C would limit the F response somewhat
since the secondary impedance is 100k, getting rather high.
|
I just cited it, I don't like it either. As You know I think that each tube
should be used for what it was meant for: the 4212 is a monster, there's no
reason to use it unless You want 100W class A SE. A Chinese 845 or 2/3
KT88s in parallel or Your 13E1 will smoothly deliver the 20-30W that are
needed to enjoy SE designs with almost any LS in almost any home (the U2
concert in S.Siro stadium with its 100'000 W is not included), if I were to
spend that money and risk my butt with 2500V I'd want to squeeze all the
juice out of it.
Ciao
Fabio
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Oskari Heinonen
Guest
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Patrick Turner
Guest
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| Posted:
Wed Jul 27, 2005 3:14 pm Post subject:
Re: The man wants to make a 212 SET amp. |
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Oskari Heinonen wrote:
Hi Oskari, your eye for detail is as fine as ever, and no I
didn't see the above, but one has to say its a spectacular amp.
It uses a little iddy biddy 845 as the driver.......
Patrick Turner. |
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