[Patrick M.B.]

I have a few VICOR 95V DC/DC converter modules and would like to use these
to feed a tube headphone amplifier.
I was thinking of using 6N7 tubes, because these yield a usefull current at
VA 95V.
Any suggestions as to circuit tolpology, headphones and better tubes at this
voltage? The purpose is to practice bass guitar without disturbing the
neighbourhood.
The heater voltage should be 24V as the input voltage of the coneverters is
24V.


Thanks for any advise.

Patrick B.

[Patrick M.B.]

"flipper" schreef in bericht
...
On Mon, 4 Dec 2006 18:41:34 +0100, "Patrick M.B."
wrote:

I have a few VICOR 95V DC/DC converter modules and would like to use these
to feed a tube headphone amplifier.
I was thinking of using 6N7 tubes, because these yield a usefull current
at
VA 95V.

Any other reason? And are you set on triodes?

According to Vicor their modules can be series connected with a
couple of steering diodes so you're not limited to 95V.

But if those are 50 watt, or more, modules it seems like over kill for
a headphone amp.

Easy way to get some HV is to connect a couple of 12.6 volt trannies
back to back, secondaries together. One drops down to 12.6 for the
filaments and it's 12.6 is multiplied back up by the other for 120VAC.


I've done that for negative bias supplies. However I have these modules,
real small and neat.

Any suggestions as to circuit tolpology, headphones and better tubes at
this
voltage? The purpose is to practice bass guitar without disturbing the
neighbourhood.
The heater voltage should be 24V as the input voltage of the coneverters
is
24V.

There are a number of ways to attack that problem. Series filaments,
for one. Two x 12.6 is close enough to 24 since I presume your 24V is
a DC regulated supply.

A DC voltage on the filaments should guarantee a humless output signal.


If for some reason you don't want to series filaments there are also
25V filament tubes. The 25L6 is a 25V filament version of the 12L6: a
pentode with 10 watt plate good for 2 watts SE at 110V B+. If you're
not averse to compactrons, and can find sockets, the 21LR8 and 21LU8
have a 14 watt Pentode and 58 mu triode in the same envelope.

The 25A6 is a small 7 pin 5 watt plate pentode originally designed for
low cost radios. It's good for a couple of watts SE at 135V. Btw,
rated .9 Watt SE with 95V. The 25C5 is similar and another in the same
general category is the 25CA5.

For twin triodes on the 24V a 20EZ7 is a 20 volt filament version of
the 12AX7 and at 100mA it's easy enough to drop the remaining 4 with a
1 watt resistor.

I don't know what you're goal is, though, other than just 'headphone'
amp and there's more than one way to skin a cat, as someone once said.

Here's a simple one that would only take one twin triode bottle. if
you don't mind a MOSFET mu follower.

http://www.geocities.com/rjm003.geo/...o/diy_twi.html


I have plenty of triodes, don't want to skimp on that. It's just that I do
not like the heavy-metal power supplies a lot.
And I always wanted to make smps-supplied audio amplifier.

I would prefer a minimal passive component circuit, that fits between the
95V of a single module.




Thanks for any advise.

Patrick B.

[Patrick M.B.]

minimal passive (components)

a circuit that uses the least possible resistors and capacitors. Often tubes
are lower cost than the heavenly specified resistors and capacitors used in
tubes-circuits.
I was thinking e.g. on direct coupled headphones as well that can stand the
dc-tube current. I wonder if these exist.

Patrick


"flipper" schreef in bericht
...
On Wed, 6 Dec 2006 15:04:58 +0100, "Patrick M.B."
wrote:


"flipper" schreef in bericht
. ..
On Mon, 4 Dec 2006 18:41:34 +0100, "Patrick M.B."
wrote:

I have a few VICOR 95V DC/DC converter modules and would like to use
these
to feed a tube headphone amplifier.
I was thinking of using 6N7 tubes, because these yield a usefull current
at
VA 95V.

Any other reason? And are you set on triodes?

According to Vicor their modules can be series connected with a
couple of steering diodes so you're not limited to 95V.

But if those are 50 watt, or more, modules it seems like over kill for
a headphone amp.

Easy way to get some HV is to connect a couple of 12.6 volt trannies
back to back, secondaries together. One drops down to 12.6 for the
filaments and it's 12.6 is multiplied back up by the other for 120VAC.


I've done that for negative bias supplies. However I have these modules,
real small and neat.

Any suggestions as to circuit tolpology, headphones and better tubes at
this
voltage? The purpose is to practice bass guitar without disturbing the
neighbourhood.
The heater voltage should be 24V as the input voltage of the coneverters
is
24V.

There are a number of ways to attack that problem. Series filaments,
for one. Two x 12.6 is close enough to 24 since I presume your 24V is
a DC regulated supply.

A DC voltage on the filaments should guarantee a humless output signal.

My point was that nominal filament voltage takes into account line
voltage variations and since your regulated 24V supply would not
exhibit that then being a volt low is acceptable.

If for some reason you don't want to series filaments there are also
25V filament tubes. The 25L6 is a 25V filament version of the 12L6: a
pentode with 10 watt plate good for 2 watts SE at 110V B+. If you're
not averse to compactrons, and can find sockets, the 21LR8 and 21LU8
have a 14 watt Pentode and 58 mu triode in the same envelope.

The 25A6 is a small 7 pin 5 watt plate pentode originally designed for
low cost radios. It's good for a couple of watts SE at 135V. Btw,
rated .9 Watt SE with 95V. The 25C5 is similar and another in the same
general category is the 25CA5.

For twin triodes on the 24V a 20EZ7 is a 20 volt filament version of
the 12AX7 and at 100mA it's easy enough to drop the remaining 4 with a
1 watt resistor.

I don't know what you're goal is, though, other than just 'headphone'
amp and there's more than one way to skin a cat, as someone once said.

Here's a simple one that would only take one twin triode bottle. if
you don't mind a MOSFET mu follower.

http://www.geocities.com/rjm003.geo/...o/diy_twi.html


I have plenty of triodes, don't want to skimp on that. It's just that I do
not like the heavy-metal power supplies a lot.
And I always wanted to make smps-supplied audio amplifier.

I would prefer a minimal passive component circuit, that fits between the
95V of a single module.

minimal passive??


Thanks for any advise.

Patrick B.

[Patrick M.B.]

The circular bridge amplifier described on
http://www.tubecad.com/october99/page11.html
seems just the conceptual circuit, fit for 2 Vicor 95V DC-DC converter
modules.
Any more-specific circuits available?
As this is a mono application I could just wire the 2 ears in series. Or
perhabs there is a derivation that would allow stereo with just 2 modules/
power supplies?

Patrick

"flipper" schreef in bericht
...
On Tue, 12 Dec 2006 20:03:01 +0100, "Patrick M.B."
wrote:

minimal passive (components)

a circuit that uses the least possible resistors and capacitors.

Of course. I just didn't see what it had to do with whether you were
MOSFET tolerant or not.

Often tubes
are lower cost than the heavenly specified resistors and capacitors used
in
tubes-circuits.

You must use components more heavenly than I do

I was thinking e.g. on direct coupled headphones as well that can stand
the
dc-tube current. I wonder if these exist.

Unlikely.

You do need to decide which you want to drive, though, because that'll
impact how much current the thing needs to pump out and then you can
think about picking tubes.


Patrick


"flipper" schreef in bericht
. ..
On Wed, 6 Dec 2006 15:04:58 +0100, "Patrick M.B."
wrote:


"flipper" schreef in bericht
m...
On Mon, 4 Dec 2006 18:41:34 +0100, "Patrick M.B."
wrote:

I have a few VICOR 95V DC/DC converter modules and would like to use
these
to feed a tube headphone amplifier.
I was thinking of using 6N7 tubes, because these yield a usefull
current
at
VA 95V.

Any other reason? And are you set on triodes?

According to Vicor their modules can be series connected with a
couple of steering diodes so you're not limited to 95V.

But if those are 50 watt, or more, modules it seems like over kill for
a headphone amp.

Easy way to get some HV is to connect a couple of 12.6 volt trannies
back to back, secondaries together. One drops down to 12.6 for the
filaments and it's 12.6 is multiplied back up by the other for 120VAC.


I've done that for negative bias supplies. However I have these modules,
real small and neat.

Any suggestions as to circuit tolpology, headphones and better tubes
at
this
voltage? The purpose is to practice bass guitar without disturbing the
neighbourhood.
The heater voltage should be 24V as the input voltage of the
coneverters
is
24V.

There are a number of ways to attack that problem. Series filaments,
for one. Two x 12.6 is close enough to 24 since I presume your 24V is
a DC regulated supply.

A DC voltage on the filaments should guarantee a humless output signal.

My point was that nominal filament voltage takes into account line
voltage variations and since your regulated 24V supply would not
exhibit that then being a volt low is acceptable.

If for some reason you don't want to series filaments there are also
25V filament tubes. The 25L6 is a 25V filament version of the 12L6: a
pentode with 10 watt plate good for 2 watts SE at 110V B+. If you're
not averse to compactrons, and can find sockets, the 21LR8 and 21LU8
have a 14 watt Pentode and 58 mu triode in the same envelope.

The 25A6 is a small 7 pin 5 watt plate pentode originally designed for
low cost radios. It's good for a couple of watts SE at 135V. Btw,
rated .9 Watt SE with 95V. The 25C5 is similar and another in the same
general category is the 25CA5.

For twin triodes on the 24V a 20EZ7 is a 20 volt filament version of
the 12AX7 and at 100mA it's easy enough to drop the remaining 4 with a
1 watt resistor.

I don't know what you're goal is, though, other than just 'headphone'
amp and there's more than one way to skin a cat, as someone once said.

Here's a simple one that would only take one twin triode bottle. if
you don't mind a MOSFET mu follower.

http://www.geocities.com/rjm003.geo/...o/diy_twi.html


I have plenty of triodes, don't want to skimp on that. It's just that I
do
not like the heavy-metal power supplies a lot.
And I always wanted to make smps-supplied audio amplifier.

I would prefer a minimal passive component circuit, that fits between
the
95V of a single module.

minimal passive??


Thanks for any advise.

Patrick B.

[boardjunkie]

On Tue, 12 Dec 2006 21:46:09 +0100, "Patrick M.B."
Btw, call me a wimp but I wouldn't DC couple the output of a headphone
amp where a tube fault, or whatever, could throw a couple hundred
volts across the noggin.

Patrick

Word.