SMPS for powering headphone amp?

Guest
I orderd the K272c headphone amp kit from Oatley Electronics. See
link:
http://secure.oatleyelectronics.com//product_info.php?products_id=1027
It uses two power sources. Two 1.5 volt batteries and two 9 volt
batteries for the 3 and 18 volt powwer requirements. I was wondering
about using a boost converter to supply the 18 volt power for the amp.
Something like this:
http://www.ebay.com/itm/DC-3-32V-Step-Up-to-5-35V-Boost-Converter-Voltage-Regulator-Power-Supply-Module-/151866847954?hash=item235bf832d2:g:NgkAAOSw5VFWMhCF
I could also use rechargeable 9 volt lithium batteries like these:
http://www.ebay.com/itm/4x-EBL-600mAh-Li-ion-9V-9-Volt-6F22-Lithium-ion-Rechargeable-Battery-Charger-/251690929804?hash=item3a99f2ce8c:g:UZcAAOSwZkJUSvtw
If I go the route of using a boost converter will I also probably need
to filter noise from the converter? I know, it sounds silly to build a
little headphone amp, but I'm curious about the "tube sound" and if my
60 year old years can even hear the difference. If the little amp does
make music sound better to me then I will be carting it around with my
mp3 player. To that end I would like it to be as small and light as
possible. Lithium batteries definitely fit the small and light
requirement compared to other batteries. I even thought about using 6
lipo cells, 5 for 18.5 volts and 1 for 3.7 volts. Since the 3.7 volts
is used for the tube filaments I think I would be well advised to use
a 3 volt regulator for longer tube life. Since I can get the lipo
cells in many different sizes I can surely find some of a size to all
fit in the same area described by the amp circuit board.
Thoughts?
Thanks,
Eric
 
On Monday, March 7, 2016 at 1:40:05 PM UTC-5, et...@whidbey.com wrote:
I orderd the K272c headphone amp kit from Oatley Electronics. See
link:
http://secure.oatleyelectronics.com//product_info.php?products_id=1027
It uses two power sources. Two 1.5 volt batteries and two 9 volt
batteries for the 3 and 18 volt powwer requirements. I was wondering
about using a boost converter to supply the 18 volt power for the amp.
Something like this:
http://www.ebay.com/itm/DC-3-32V-Step-Up-to-5-35V-Boost-Converter-Voltage-Regulator-Power-Supply-Module-/151866847954?hash=item235bf832d2:g:NgkAAOSw5VFWMhCF
I could also use rechargeable 9 volt lithium batteries like these:
http://www.ebay.com/itm/4x-EBL-600mAh-Li-ion-9V-9-Volt-6F22-Lithium-ion-Rechargeable-Battery-Charger-/251690929804?hash=item3a99f2ce8c:g:UZcAAOSwZkJUSvtw
If I go the route of using a boost converter will I also probably need
to filter noise from the converter? I know, it sounds silly to build a
little headphone amp, but I'm curious about the "tube sound" and if my
60 year old years can even hear the difference. If the little amp does
make music sound better to me then I will be carting it around with my
mp3 player. To that end I would like it to be as small and light as
possible. Lithium batteries definitely fit the small and light
requirement compared to other batteries. I even thought about using 6
lipo cells, 5 for 18.5 volts and 1 for 3.7 volts. Since the 3.7 volts
is used for the tube filaments I think I would be well advised to use
a 3 volt regulator for longer tube life. Since I can get the lipo
cells in many different sizes I can surely find some of a size to all
fit in the same area described by the amp circuit board.
Thoughts?
Thanks,
Eric
Click to expand...

Hmm, I'm not an audio guy, but I think "tube sound" is mostly
the absence of cross over distortion... which I assume modern amps
do much better than the first transistorized ones. And soft clipping
at the peaks of the signal... you could do the soft clipping with
transistors/ diode/ opamps.
https://en.wikipedia.org/wiki/Tube_sound#Tube_sound_from_transistor_amplifiers

I know, I didn't answer your question. You might pospone battery replacements
till you hear if you like the sound.

George
 
et...@whidbey.com wrote:
I orderd the K272c headphone amp kit from Oatley Electronics. See
link:

http://secure.oatleyelectronics.com//product_info.php?products_id=1027

It uses two power sources. Two 1.5 volt batteries and two 9 volt
batteries for the 3 and 18 volt powwer requirements. I was wondering
about using a boost converter to supply the 18 volt power for the amp.
Click to expand...

** Stop wondering - it's a damn fool idea.

The running time with good alkaline cells for both batteries is about 100 hours.

With rechargeables and a boost converter, the time is about 3-5 hours

The whole circuit is a PILE OF JUNK.

Forget it.


..... Phil
 
On 2016-03-07, etpm@whidbey.com <etpm@whidbey.com> wrote:
I orderd the K272c headphone amp kit from Oatley Electronics. See
link:
http://secure.oatleyelectronics.com//product_info.php?products_id=1027
It uses two power sources. Two 1.5 volt batteries and two 9 volt
batteries for the 3 and 18 volt powwer requirements. I was wondering
about using a boost converter to supply the 18 volt power for the amp.
Something like this:

http://www.ebay.com/itm/DC-3-32V-Step-Up-to-5-35V-Boost-Converter-Voltage-Regulator-Power-Supply-Module-/151866847954?hash=item235bf832d2:g:NgkAAOSw5VFWMhCF
Click to expand...

Sure that would work, the circyit diagram shows the 3V and the 18V
having the negative terminal common, and for that boost regulator
that's a requirement.

At $2.33 it's over-priced and at 2A capability massivly over-sized

I'd go with a more compact converter,
http://www.ebay.com/itm/5V-to-12V-DC-DC-Converter-Step-Up-Module-5W-USB-Power-Supply-Boost-Module-/331616617766?hash=item4d35e40526:g:sxEAAOSwgQ9VuZuK

it's likely to be more efficient at the low powere level needed for
tubes.

this one will need some modification to get 18V
change R2 to 470K - that should be close enough.

possible. Lithium batteries definitely fit the small and light
requirement compared to other batteries. I even thought about using 6
lipo cells, 5 for 18.5 volts and 1 for 3.7 volts. Since the 3.7 volts
is used for the tube filaments I think I would be well advised to use
a 3 volt regulator for longer tube life. Since I can get the lipo
cells in many different sizes I can surely find some of a size to all
fit in the same area described by the amp circuit board.
Thoughts?
Click to expand...

the real power hog will be the filaments on the tubes and replacing
the built-up linear 1.2v regulator (Q1,R10,LED1) with a switching buck
regulator will increase battery life by a factor of about 2

http://www.ebay.com/itm/Mini-DC-DC-Buck-Converter-Step-Down-Module-Power-Supply-For-aeromodelling-/400362498785?hash=item5d3776eae1:g:RucAAOxyk99RzT5d

unfortunately that one needs 4V or more to run, so 2 lithium cells, or 4 AAs

--
\_(ツ)_
 
On Mon, 07 Mar 2016 10:45:53 -0800, etpm@whidbey.com wrote:

I orderd the K272c headphone amp kit from Oatley Electronics. See
link:
http://secure.oatleyelectronics.com//product_info.php?products_id=1027
It uses two power sources. Two 1.5 volt batteries and two 9 volt
batteries for the 3 and 18 volt powwer requirements. I was wondering
about using a boost converter to supply the 18 volt power for the amp.
Something like this:
http://www.ebay.com/itm/DC-3-32V-Step-Up-to-5-35V-Boost-Converter-Voltage-Regulator-Power-Supply-Module-/151866847954?hash=item235bf832d2:g:NgkAAOSw5VFWMhCF
I could also use rechargeable 9 volt lithium batteries like these:
http://www.ebay.com/itm/4x-EBL-600mAh-Li-ion-9V-9-Volt-6F22-Lithium-ion-Rechargeable-Battery-Charger-/251690929804?hash=item3a99f2ce8c:g:UZcAAOSwZkJUSvtw
If I go the route of using a boost converter will I also probably need
to filter noise from the converter? I know, it sounds silly to build a
little headphone amp, but I'm curious about the "tube sound" and if my
60 year old years can even hear the difference. If the little amp does
make music sound better to me then I will be carting it around with my
mp3 player. To that end I would like it to be as small and light as
possible. Lithium batteries definitely fit the small and light
requirement compared to other batteries. I even thought about using 6
lipo cells, 5 for 18.5 volts and 1 for 3.7 volts. Since the 3.7 volts
is used for the tube filaments I think I would be well advised to use
a 3 volt regulator for longer tube life. Since I can get the lipo
cells in many different sizes I can surely find some of a size to all
fit in the same area described by the amp circuit board.
Thoughts?
Thanks,
Eric
Click to expand...

That amp is insane. The max rated cathode current for those silly
little tubes is 500 uA, so they can't usefully drive headphones.
Looking at the board, they are probably making a symbolic pass through
the tubes into an IC that actually drives the phones.

What do they claim for power output per channel? A schematic would be
amusing.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics
 
John Larkin wrote:
etpm@whidbey.com wrote:

I orderd the K272c headphone amp kit from Oatley Electronics. See
link:

http://secure.oatleyelectronics.com//product_info.php?products_id=1027




That amp is insane. The max rated cathode current for those silly
little tubes is 500 uA, so they can't usefully drive headphones.
Looking at the board, they are probably making a symbolic pass through
the tubes into an IC that actually drives the phones.

What do they claim for power output per channel? A schematic would be
amusing.
Click to expand...

** It's there in the link:

http://secure.oatleyelectronics.com/files/K272C.pdf

The OPA2134 can deliver 40mA, which is adequate.


..... Phil
 
On Tue, 8 Mar 2016 17:20:08 -0800 (PST), Phil Allison
<pallison49@gmail.com> wrote:

John Larkin wrote:
etpm@whidbey.com wrote:

I orderd the K272c headphone amp kit from Oatley Electronics. See
link:

http://secure.oatleyelectronics.com//product_info.php?products_id=1027




That amp is insane. The max rated cathode current for those silly
little tubes is 500 uA, so they can't usefully drive headphones.
Looking at the board, they are probably making a symbolic pass through
the tubes into an IC that actually drives the phones.

What do they claim for power output per channel? A schematic would be
amusing.


** It's there in the link:

http://secure.oatleyelectronics.com/files/K272C.pdf

The OPA2134 can deliver 40mA, which is adequate.


.... Phil
Click to expand...

OK, it is an IC output stage. So the tube is cosmetic. Cosmetic and
ugly at the same time.

I wonder why people think they like distortion. The guys who mastered
the music have a zillion dollars worth of gear and hundreds of years
of experience. You'd thing that if they wanted distortion, or tube
sound, they would put that on the CD.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics
 
John Larkin wrote:
That amp is insane. The max rated cathode current for those silly
little tubes is 500 uA, so they can't usefully drive headphones.
Click to expand...

** The 6418 mini-tube is described as a pentode "power amplifier" with rated output of 2.2mW at 12% THD.

http://www.mif.pg.gda.pl/homepages/frank/sheets/127/6/6418.pdf

Seems they were originally made for use in pocket worn hearing aids that employed 22V and 1.5V dry batteries and drove a special in ear transducer that was VERY efficient.

Such tubes competed with Germanium transistors in that job until about the early 60s.

http://www.ck722museum.com/page3.html


.... Phil
 
On Tuesday, March 8, 2016 at 8:54:44 AM UTC-8, John Larkin wrote:
On Mon, 07 Mar 2016 10:45:53 -0800, etpm@whidbey.com wrote:

I orderd the K272c headphone amp kit from Oatley Electronics.

That amp is insane. The max rated cathode current for those silly
little tubes is 500 uA, so they can't usefully drive headphones.
Looking at the board, they are probably making a symbolic pass through
the tubes into an IC that actually drives the phones.
Click to expand...

So true. Schematic here:<http://secure.oatleyelectronics.com/files/K272C.pdf>

Note the LED used to regulate the heater supply...
The tube gain and input impedance and output drive
are all ... underutilized.

It DOES, however, have impressive immunity to input overdrive...
 
On Wed, 9 Mar 2016 01:06:09 -0800 (PST), Phil Allison
<pallison49@gmail.com> wrote:

John Larkin wrote:



That amp is insane. The max rated cathode current for those silly
little tubes is 500 uA, so they can't usefully drive headphones.


** The 6418 mini-tube is described as a pentode "power amplifier" with rated output of 2.2mW at 12% THD.

http://www.mif.pg.gda.pl/homepages/frank/sheets/127/6/6418.pdf

Seems they were originally made for use in pocket worn hearing aids that employed 22V and 1.5V dry batteries and drove a special in ear transducer that was VERY efficient.

Such tubes competed with Germanium transistors in that job until about the early 60s.

http://www.ck722museum.com/page3.html


... Phil
Click to expand...

I used to buy CK722s from Allied for about $5, a month's alowance. I
still have a few.

https://dl.dropboxusercontent.com/u/53724080/Oldies/Ck722-0A.JPG

They were really pretty awful electrically.

Bill Wagner kindly sent me a couple of proximity fuze tubes,
super-rugged versions of the hearing-aid tubes.

https://dl.dropboxusercontent.com/u/53724080/Prox/Prox_Tubes.jpg

https://dl.dropboxusercontent.com/u/53724080/Prox/2D29.JPG

https://dl.dropboxusercontent.com/u/53724080/Prox/Prox1.jpg

I still boggle at the idea of firing tube circuits out of cannons at
20,000 g's.







--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
On Tue, 08 Mar 2016 18:38:05 -0800, John Larkin
<jjlarkin@highlandtechnology.com> wrote:

On Tue, 8 Mar 2016 17:20:08 -0800 (PST), Phil Allison
pallison49@gmail.com> wrote:

John Larkin wrote:
etpm@whidbey.com wrote:

I orderd the K272c headphone amp kit from Oatley Electronics. See
link:

http://secure.oatleyelectronics.com//product_info.php?products_id=1027




That amp is insane. The max rated cathode current for those silly
little tubes is 500 uA, so they can't usefully drive headphones.
Looking at the board, they are probably making a symbolic pass through
the tubes into an IC that actually drives the phones.

What do they claim for power output per channel? A schematic would be
amusing.


** It's there in the link:

http://secure.oatleyelectronics.com/files/K272C.pdf

The OPA2134 can deliver 40mA, which is adequate.


.... Phil



OK, it is an IC output stage. So the tube is cosmetic. Cosmetic and
ugly at the same time.

I wonder why people think they like distortion.
Click to expand...
<SNIP>
Well, for less than 30 frog pelts I may find out. Then again maybe
not. By the way, my grandfather, William B. Snow, was a sound
engineer. He worked for years for Bell Labs. He did pioneering work on
binaural sound and sonar. He had a sound lab in his house and when I
was a kid I loved going into his lab where he would have me speak into
a microphone and show me what my voice looked like on an oscilloscope.
He showed me the different frequencies that made up my voice and all
sorts of other cool stuff. I sure wish I could speak to him now.
Eric
 
On Wed, 09 Mar 2016 10:37:27 -0800, John Larkin
<jjlarkin@highlandtechnology.com> wrote:

On Wed, 9 Mar 2016 01:06:09 -0800 (PST), Phil Allison
pallison49@gmail.com> wrote:

John Larkin wrote:



That amp is insane. The max rated cathode current for those silly
little tubes is 500 uA, so they can't usefully drive headphones.


** The 6418 mini-tube is described as a pentode "power amplifier" with rated output of 2.2mW at 12% THD.

http://www.mif.pg.gda.pl/homepages/frank/sheets/127/6/6418.pdf

Seems they were originally made for use in pocket worn hearing aids that employed 22V and 1.5V dry batteries and drove a special in ear transducer that was VERY efficient.

Such tubes competed with Germanium transistors in that job until about the early 60s.

http://www.ck722museum.com/page3.html


... Phil


I used to buy CK722s from Allied for about $5, a month's alowance. I
still have a few.

https://dl.dropboxusercontent.com/u/53724080/Oldies/Ck722-0A.JPG

They were really pretty awful electrically.

Bill Wagner kindly sent me a couple of proximity fuze tubes,
super-rugged versions of the hearing-aid tubes.

https://dl.dropboxusercontent.com/u/53724080/Prox/Prox_Tubes.jpg

https://dl.dropboxusercontent.com/u/53724080/Prox/2D29.JPG

https://dl.dropboxusercontent.com/u/53724080/Prox/Prox1.jpg

I still boggle at the idea of firing tube circuits out of cannons at
20,000 g's.
Click to expand...
Years ago I read a short article written by an American man who was a
soldier during WW2. He was sent to Britain as part of a crew that were
manning anti-aircraft guns and shooting American shells. Their success
rate was much higher than the British. So the Americans bragged about
how they were such good shots and denigrated the British for being
such poor shots. The Americans were shooting the new shells with the
new and secret proximity fuzes. Of course the Brits were eventually
told and got to use the new proximity devices. I had no idea the amp
kit I bought uses the consumer version of the same type of tube. Cool.
Eric
 
On Wed, 09 Mar 2016 13:33:37 -0800, etpm@whidbey.com wrote:

On Wed, 09 Mar 2016 10:37:27 -0800, John Larkin
jjlarkin@highlandtechnology.com> wrote:

On Wed, 9 Mar 2016 01:06:09 -0800 (PST), Phil Allison
pallison49@gmail.com> wrote:

John Larkin wrote:



That amp is insane. The max rated cathode current for those silly
little tubes is 500 uA, so they can't usefully drive headphones.


** The 6418 mini-tube is described as a pentode "power amplifier" with rated output of 2.2mW at 12% THD.

http://www.mif.pg.gda.pl/homepages/frank/sheets/127/6/6418.pdf

Seems they were originally made for use in pocket worn hearing aids that employed 22V and 1.5V dry batteries and drove a special in ear transducer that was VERY efficient.

Such tubes competed with Germanium transistors in that job until about the early 60s.

http://www.ck722museum.com/page3.html


... Phil


I used to buy CK722s from Allied for about $5, a month's alowance. I
still have a few.

https://dl.dropboxusercontent.com/u/53724080/Oldies/Ck722-0A.JPG

They were really pretty awful electrically.

Bill Wagner kindly sent me a couple of proximity fuze tubes,
super-rugged versions of the hearing-aid tubes.

https://dl.dropboxusercontent.com/u/53724080/Prox/Prox_Tubes.jpg

https://dl.dropboxusercontent.com/u/53724080/Prox/2D29.JPG

https://dl.dropboxusercontent.com/u/53724080/Prox/Prox1.jpg

I still boggle at the idea of firing tube circuits out of cannons at
20,000 g's.
Years ago I read a short article written by an American man who was a
soldier during WW2. He was sent to Britain as part of a crew that were
manning anti-aircraft guns and shooting American shells. Their success
rate was much higher than the British. So the Americans bragged about
how they were such good shots and denigrated the British for being
such poor shots. The Americans were shooting the new shells with the
new and secret proximity fuzes. Of course the Brits were eventually
told and got to use the new proximity devices. I had no idea the amp
kit I bought uses the consumer version of the same type of tube. Cool.
Eric
Click to expand...

Good book:

http://www.amazon.com/deadly-fuze-secret-weapon-World/dp/0891410872/ref=sr_1_1?ie=UTF8&qid=1457573259&sr=8-1&keywords=deadly+fuze




--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com
 
On Mon, 7 Mar 2016 12:54:29 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

On Monday, March 7, 2016 at 1:40:05 PM UTC-5, et...@whidbey.com wrote:
I orderd the K272c headphone amp kit from Oatley Electronics. See
link:
http://secure.oatleyelectronics.com//product_info.php?products_id=1027
It uses two power sources. Two 1.5 volt batteries and two 9 volt
batteries for the 3 and 18 volt powwer requirements. I was wondering
about using a boost converter to supply the 18 volt power for the amp.
Something like this:
http://www.ebay.com/itm/DC-3-32V-Step-Up-to-5-35V-Boost-Converter-Voltage-Regulator-Power-Supply-Module-/151866847954?hash=item235bf832d2:g:NgkAAOSw5VFWMhCF
I could also use rechargeable 9 volt lithium batteries like these:
http://www.ebay.com/itm/4x-EBL-600mAh-Li-ion-9V-9-Volt-6F22-Lithium-ion-Rechargeable-Battery-Charger-/251690929804?hash=item3a99f2ce8c:g:UZcAAOSwZkJUSvtw
If I go the route of using a boost converter will I also probably need
to filter noise from the converter? I know, it sounds silly to build a
little headphone amp, but I'm curious about the "tube sound" and if my
60 year old years can even hear the difference. If the little amp does
make music sound better to me then I will be carting it around with my
mp3 player. To that end I would like it to be as small and light as
possible. Lithium batteries definitely fit the small and light
requirement compared to other batteries. I even thought about using 6
lipo cells, 5 for 18.5 volts and 1 for 3.7 volts. Since the 3.7 volts
is used for the tube filaments I think I would be well advised to use
a 3 volt regulator for longer tube life. Since I can get the lipo
cells in many different sizes I can surely find some of a size to all
fit in the same area described by the amp circuit board.
Thoughts?
Thanks,
Eric

Hmm, I'm not an audio guy, but I think "tube sound" is mostly
the absence of cross over distortion... which I assume modern amps
do much better than the first transistorized ones. And soft clipping
at the peaks of the signal... you could do the soft clipping with
transistors/ diode/ opamps.
https://en.wikipedia.org/wiki/Tube_sound#Tube_sound_from_transistor_amplifiers

I know, I didn't answer your question. You might pospone battery replacements
till you hear if you like the sound.

George
Click to expand...
Thanks for the links George. If the little amp makes sound I like I
may indeed take advantage of the links you posted.
Eric
 
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