[robert casey]

That project where I built a SE stereo amp inside a Sony receiver using
a pair of 50C5s and reworked power transformers got rebuilt using *real*
output transformers. Made by Transcendar Transformer, bought off ebay.
And sounds a lot better. Everyone was right saying that I was nuts to
try to use power transformers! :-)



See
http://home.earthlink.net/~wa2ise/sonytubed.html for more details and
measurements.

[robert casey]

Bret Ludwig wrote:

On Mar 27, 12:23 am, robert casey wrote:

That project where I built a SE stereo amp inside a Sony receiver using
a pair of 50C5s and reworked power transformers got rebuilt using *real*
output transformers. Made by Transcendar Transformer, bought off ebay.
And sounds a lot better. Everyone was right saying that I was nuts to
try to use power transformers! :-)



Yes, they were.

For one thing, power transformers have poor bandpass by design. For
another, they are built with tight magnetic coupling and a SE amp
needs to have a gapped core.

Of course, but I did restack the lams to create the gapped core.
Helped, but not enough. Wrong kind of lam steel for real audio work...

[John Byrns]

In article .com,
"Bret Ludwig" wrote:

On Mar 27, 12:23 am, robert casey wrote:
That project where I built a SE stereo amp inside a Sony receiver using
a pair of 50C5s and reworked power transformers got rebuilt using *real*
output transformers. Made by Transcendar Transformer, bought off ebay.
And sounds a lot better. Everyone was right saying that I was nuts to
try to use power transformers! :-)

Yes, they were.

For one thing, power transformers have poor bandpass by design. For
another, they are built with tight magnetic coupling and a SE amp
needs to have a gapped core.

Bret, can you explain what "tight magnetic coupling" has to do with
having "a gapped core"? I thought SE amps need an output transformer
with both "tight magnetic coupling" and a "a gapped core".


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[John Byrns]

In article .com,
"Bret Ludwig" wrote:

On Mar 27, 9:01 am, John Byrns wrote:
In article .com,
"Bret Ludwig" wrote:

On Mar 27, 12:23 am, robert casey wrote:
That project where I built a SE stereo amp inside a Sony receiver using
a pair of 50C5s and reworked power transformers got rebuilt using *real*
output transformers. Made by Transcendar Transformer, bought off ebay.
And sounds a lot better. Everyone was right saying that I was nuts to
try to use power transformers! :-)

Yes, they were.

For one thing, power transformers have poor bandpass by design. For
another, they are built with tight magnetic coupling and a SE amp
needs to have a gapped core.

Bret, can you explain what "tight magnetic coupling" has to do with
having "a gapped core"? I thought SE amps need an output transformer
with both "tight magnetic coupling" and a "a gapped core".


I think you know full well.

Actually I didn't have a clue what you menat.

It is not the windings which need loose coupling to the core, but the
core itself must be kept from saturation by standing DC current. This
is done by separating the lams somewhat, but the tradeoff is that
primary inductance is hugely less.

That's all fine, but what does it have to do with "tight magnetic
coupling"? Maybe the problem is that I don't know what the term "tight
magnetic coupling" means.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/