[Iain Churches[_2_]]

"Don Pearce" wrote in message
...
On Sun, 20 Dec 2009 12:22:40 +0000 (GMT), Jim Lesurf
wrote:

I guess designers of commercial audio amps back then were more habituated
to using transformers than nowdays. I didn't know about the above, but
recall that some early domestic transistor amps included things like
coupling transformers.

How about a current guitar practice amplifier?

http://www.soundthoughts.co.uk/look/pignose.jpg

The idea is to sound like a proper valve guitar amplifier, and it sort
of does it.


The Pignose is brilliant. I have one.
http://www.kolumbus.fi/iain.churches/Pics/Pignose.jpg

A huge sound from a tiny amp:-)

Iain

[Don Pearce[_3_]]

On Sun, 20 Dec 2009 18:17:48 +0000 (GMT), Jim Lesurf
wrote:

In article , Don Pearce
wrote:
On Sun, 20 Dec 2009 12:22:40 +0000 (GMT), Jim Lesurf
wrote:

I guess designers of commercial audio amps back then were more
habituated to using transformers than nowdays. I didn't know about the
above, but recall that some early domestic transistor amps included
things like coupling transformers.

How about a current guitar practice amplifier?

http://www.soundthoughts.co.uk/look/pignose.jpg

The idea is to sound like a proper valve guitar amplifier, and it sort
of does it.

The transformers look quite small. What's the scale of the picture?

I did once do a 'theoretical' design using two bipolars and couple of
transformers to make a SET power amp, just to work out what kind of gain,
etc, you might get. But never built it as it didn't seem worth trying to
get suitable transformers. Maybe the above did it anyway? :-)

Slainte,

Jim

The whole thing is small - the long side is about three inches. This
is a battery powered amplifier that sees a lot of use in studios. It
sounds "big" when recorded.

d

[Don Pearce[_3_]]

On Mon, 21 Dec 2009 17:27:20 +0200, "Iain Churches"
wrote:


"Don Pearce" wrote in message
...
On Sun, 20 Dec 2009 12:22:40 +0000 (GMT), Jim Lesurf
wrote:

I guess designers of commercial audio amps back then were more habituated
to using transformers than nowdays. I didn't know about the above, but
recall that some early domestic transistor amps included things like
coupling transformers.

How about a current guitar practice amplifier?

http://www.soundthoughts.co.uk/look/pignose.jpg

The idea is to sound like a proper valve guitar amplifier, and it sort
of does it.


The Pignose is brilliant. I have one.
http://www.kolumbus.fi/iain.churches/Pics/Pignose.jpg

A huge sound from a tiny amp:-)

Iain


It isn't the same without the proper pig's nose volume knob.

d

[David Looser]

"flipper" wrote

My 'mini guitar amp' is a similar idea, except it's real tubes with
more controls, headphone, and line out for recording.


Interesting choice of valve. Apparently it was designed for use in cascode
VHF amplifiers in TV sets. I guess the nearest European equivalent would be
the ECC84. If anyone wants to try building one I've got a box-full of the
PCC84 (same thing but with 7.0V heater).

David.

[Keith G[_2_]]

"flipper" wrote


My 'mini guitar amp' is a similar idea, except it's real tubes with
more controls, headphone, and line out for recording.

http://flipperhome.dyndns.org/Gemini%20x2.htm




What I lovely little project - almost makes me wish I was still messing
about with that good DIY valvey stuff!!

@:-)

[David Looser]

"flipper" wrote

I used a number of tricks. Current mirror under the power tubes for
automatic bias, input FET buffer done as a HV 'tube' emulator, NPN
follower tone stack buffer, and NPN phase splitter. But the tubes do
the 'music' work.

Are you using the two halves of one of your double triodes as a push-pull
output pair? I have the service manual somewhere for an Ampex 451 tape
recorder (circa 1965). That uses two double triodes in the line amp, the
second (a 12AT7) configured as a push-pull pair. From the photo it looks as
though your output transformer is a line-matching transformer for 70V/100V
line, such a transformer wouldn't have been designed to cope with DC in the
primary. But if you were able to drive it push-pull you'd get DC
cancellation in the core.

David.

[Iain Churches[_2_]]

"flipper" wrote in message
...
On Mon, 21 Dec 2009 17:27:20 +0200, "Iain Churches"
wrote:


"Don Pearce" wrote in message
...
On Sun, 20 Dec 2009 12:22:40 +0000 (GMT), Jim Lesurf
wrote:

I guess designers of commercial audio amps back then were more
habituated
to using transformers than nowdays. I didn't know about the above, but
recall that some early domestic transistor amps included things like
coupling transformers.

How about a current guitar practice amplifier?

http://www.soundthoughts.co.uk/look/pignose.jpg

The idea is to sound like a proper valve guitar amplifier, and it sort
of does it.


The Pignose is brilliant. I have one.
http://www.kolumbus.fi/iain.churches/Pics/Pignose.jpg

A huge sound from a tiny amp:-)

My 'mini guitar amp' is a similar idea, except it's real tubes with
more controls, headphone, and line out for recording.

http://flipperhome.dyndns.org/Gemini%20x2.htm


Excellent:-)
Pleased to see that there is someone still left on
UKRA who actually builds something, and with valves
too.

Iain

[Iain Churches[_2_]]

"Don Pearce" wrote in message
...
On Mon, 21 Dec 2009 17:27:20 +0200, "Iain Churches"
wrote:


"Don Pearce" wrote in message
...
On Sun, 20 Dec 2009 12:22:40 +0000 (GMT), Jim Lesurf
wrote:

I guess designers of commercial audio amps back then were more
habituated
to using transformers than nowdays. I didn't know about the above, but
recall that some early domestic transistor amps included things like
coupling transformers.

How about a current guitar practice amplifier?

http://www.soundthoughts.co.uk/look/pignose.jpg

The idea is to sound like a proper valve guitar amplifier, and it sort
of does it.


The Pignose is brilliant. I have one.
http://www.kolumbus.fi/iain.churches/Pics/Pignose.jpg

A huge sound from a tiny amp:-)

Iain


It isn't the same without the proper pig's nose volume knob.


Rats!. Do you think mine is a worthless Chinese copy?
Its output is tiny but its sound it *huge*
-

[Don Pearce[_3_]]

On Wed, 23 Dec 2009 08:50:34 +0200, "Iain Churches"
wrote:


"Don Pearce" wrote in message
...
On Mon, 21 Dec 2009 17:27:20 +0200, "Iain Churches"
wrote:


"Don Pearce" wrote in message
...
On Sun, 20 Dec 2009 12:22:40 +0000 (GMT), Jim Lesurf
wrote:

I guess designers of commercial audio amps back then were more
habituated
to using transformers than nowdays. I didn't know about the above, but
recall that some early domestic transistor amps included things like
coupling transformers.

How about a current guitar practice amplifier?

http://www.soundthoughts.co.uk/look/pignose.jpg

The idea is to sound like a proper valve guitar amplifier, and it sort
of does it.


The Pignose is brilliant. I have one.
http://www.kolumbus.fi/iain.churches/Pics/Pignose.jpg

A huge sound from a tiny amp:-)

Iain


It isn't the same without the proper pig's nose volume knob.


Rats!. Do you think mine is a worthless Chinese copy?
Its output is tiny but its sound it *huge*
-

I'm sure it is real. Those must number among the last properly
hand-made products in the world - no chance of mass production in
Dafen.

d

[TonyL]

flipper wrote:

http://flipperhome.dyndns.org/Gemini%20x2.htm


Excellent:-)

Thank you.

Pleased to see that there is someone still left on
UKRA who actually builds something, and with valves
too.

Who knows. Maybe this year I'll get around to building the 807 amp
I've already got the tubes for.


Hey Flipper,

Would love to see your amp but I've been getting 404s.

Any suggestions ?

TIA

TonyL

[TonyL]

flipper wrote:
On Wed, 30 Dec 2009 12:02:59 -0000, "TonyL"
wrote:

flipper wrote:

http://flipperhome.dyndns.org/Gemini%20x2.htm


Excellent:-)

Thank you.

Pleased to see that there is someone still left on
UKRA who actually builds something, and with valves
too.

Who knows. Maybe this year I'll get around to building the 807 amp
I've already got the tubes for.


Hey Flipper,

Would love to see your amp but I've been getting 404s.

Any suggestions ?

Yeah, I'll reboot the server.

Sorry about that. It's running on a little webpal that's sitting on
the edge and I've got a new puppy that loves to smack the thing into
brain dead. He also likes to pull cables out of the router on that
segment..

I just moved it to a more stable location so hopefully it'll stay up
longer.


Thanks Flipper, Gotit :-) Nice work !

Any chance of seeing a schematic ?

[Don Pearce[_3_]]

On Wed, 30 Dec 2009 15:52:33 -0600, flipper wrote:

Well, there's some potentially proprietary stuff in there so I don't
publish that one.

I can talk about it, though.

By publishing you establish your priority, so go ahead.

d