Hi all
I want to build a stereo power amp using two sets of 6L6 tubes in push pull
and achieve about 50-60 watts per channel with distortion of 2% or less.
I would like to use readily available output transformers such as sold by
AES.
Can anyone refer me to some schematics or books?
Regards
Dave

this one looks cool
http://www.appelt4u.de/pp-6l6gc/e-index.htm

but there are lots of schems out there
any of the 6l6 amp family can be converted.

look up 6l6 schematics in google and go browsing.

doug


"David" wrote in message
...
Hi all
I want to build a stereo power amp using two sets of 6L6 tubes in push
pull
and achieve about 50-60 watts per channel with distortion of 2% or less.
I would like to use readily available output transformers such as sold by
AES.
Can anyone refer me to some schematics or books?
Regards
Dave

Hi all
I want to build a stereo power amp using two sets of 6L6 tubes in push pull
and achieve about 50-60 watts per channel with distortion of 2% or less.
I would like to use readily available output transformers such as sold by
AES.
Can anyone refer me to some schematics or books?
Regards
Dave

The RCA manual has a very good section on the 6L6GC. Hammond puts out the
1650N
output which is pretty good. Punch in "tube data" into the Google search
engine and have a printer ready. I think it's called Frank's.

There are dozens even hundreds of them. I would start with your local library,
the Audio Cyclopedia, or Google the internet for schematics. Dyna, VTL,
Marantz, Audio Research all worth looking at.

Any VTL dealer should give you a copy of the VTL book which will give
you their schematics. Their amps are usually clones of Radfords or
Marantzes.

All the tube and transformer manufacturers had free books they gave to
hobbyists with pet circuits to use their tubes or transformers. As well
there were dozens of books with DIY amp designs which you can get on
interlibrary loan, as well as Sams Photofacts of popular models.

Currently in print you can get repro's of the over rated Radiotron
Designers handbook as well as some RCA and Brit tube manuals from
AudioXPress, and if you read German there's Rainer zur Linde's
"Rohrenverstarker fur Hi-Fi und Gitarren" or some such. If you read
Japanese you have it made because there are dozens of books.

I would consider using either a Lars Lundahl or Sowter output
transformer, they seem to be the best available without being able to
speak Japanese. I would use a power transformer from an affordable US
source such as the many sold for guitar amp use as replacements for
Fender amps. In the music industry there is a big mark up (the "A Mark"
is 50%) so having a business license or even a little good Social
Engineering will get you one wholesale. Retail pricing on them from
guitar amp suppliers is a buttf***, but wholesale makes them not too
bad. A toroidal power transformer would be OK but toroidal outputs,
though available, tend to suck.

Ideally you will have a separate DC supply for the heaters which
should be designed for soft start. You will probably want to use a 3
terminal regulator and a pass transistor.

On 2 Jan 2005 17:20:18 -0800, wrote:

Any VTL dealer should give you a copy of the VTL book which will give
you their schematics. Their amps are usually clones of Radfords or
Marantzes.

All the tube and transformer manufacturers had free books they gave to
hobbyists with pet circuits to use their tubes or transformers. As well
there were dozens of books with DIY amp designs which you can get on
interlibrary loan, as well as Sams Photofacts of popular models.

Currently in print you can get repro's of the over rated Radiotron
Designers handbook as well as some RCA and Brit tube manuals from
AudioXPress, and if you read German there's Rainer zur Linde's
"Rohrenverstarker fur Hi-Fi und Gitarren" or some such. If you read
Japanese you have it made because there are dozens of books.

I would consider using either a Lars Lundahl or Sowter output
transformer, they seem to be the best available without being able to
speak Japanese. I would use a power transformer from an affordable US
source such as the many sold for guitar amp use as replacements for
Fender amps. In the music industry there is a big mark up (the "A Mark"
is 50%) so having a business license or even a little good Social
Engineering will get you one wholesale. Retail pricing on them from
guitar amp suppliers is a buttf***, but wholesale makes them not too
bad. A toroidal power transformer would be OK but toroidal outputs,
though available, tend to suck.

Ideally you will have a separate DC supply for the heaters which
should be designed for soft start. You will probably want to use a 3
terminal regulator and a pass transistor.

DC for all heaters or just the front end? How about a switcher for the HV
power supply running at few hundred kHz? I know that this is a sacrilege in
some circles but I like to exploit the best of all worlds. By definition
tradition has limitations

--

Boris Mohar

DC for all heaters or just the front end? How about a switcher for
the HV
power supply running at few hundred kHz? I know that this is a
sacrilege in
some circles but I like to exploit the best of all worlds. By
definition
tradition has limitations

The preamp tubes are what need DC from a noise standpoint but the
power tubes need to be stopped from pulling excess current on startup.
Limiting current by series resistance is wasteful, and designing a
current limited supply with foldback is elegant but the limits will
have to be set to the current draw for the tubes involved. Its simplest
and easiest to build one DC regulated supply and ramp it over a time
interval.

Designing a switcher for B+ is possible, but probably beyond the
budget and expertise of the poster. Such a supply properly packaged for
universal use would probably be a viable commercial item, but building
switchers means having in house inductor building and design
capabilities. It would also have to be built pretty RF-tight and would
still require a substantial capacitor bank for energy storage. Linear
supplies are the way to go.