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Many SET builders like to use "industrial control transformers" for
power supplies. I looked through some catalogs and noticed a few
things:

1. The vast majority are designed to be mounted in electrical junction
boxes and have the taps on the top. The few with flying leads, again,
have them coming out the top.

2. Usually they have symmetrical groups of windings for 115, 230, or
460 volts., no center taps. So you tend to get awkward voltages either
on the lowish or highish side if you use capacitor filters. Choke
filters are not really feasible unless you build a separate power
supply chassis and even then they get expensive if you want reasonable
power levels.

3. Of course there is no heater or bias supply winding. So separate
supplies are de rigeur.

For most projects, using guitar amp transformers is the best way to
go especially if you can get them at dealer pricing.

[Peter Wieck]

On Nov 9, 2:29*am, wrote:
*Many SET builders like to use "industrial control transformers" for
power supplies. I looked through some catalogs and noticed a few
things:

1. The vast majority are designed to be mounted in electrical junction
boxes and have the taps on the top. The few with flying leads, again,
have them coming out the top.

*2. Usually they have symmetrical groups of windings for 115, 230, or
460 volts., no center taps. So you tend to get awkward voltages either
on the lowish or highish side if you use capacitor filters. Choke
filters are not really feasible unless you build a separate power
supply chassis and even then they get expensive if you want reasonable
power levels.

*3. Of course there is no heater or bias supply winding. So separate
supplies are de rigeur.

*For most projects, using guitar amp transformers is the best way to
go especially if you can get them at dealer pricing.

A couple of brief answers, some humorous, some not so much.

a) SET builders tend to be a few geese short of a gaggle in any case,
so the configuration of the transformer will not be at issue. Given
the intended results, awkwardness adds to the appeal.

b) Quite a few pieces of vintage equipment that I have had come across
my bench recently (Tandberg, as it happens) has top-lead transformers.
Given that common sense (which isn't, really) suggests that there
should be a cage over hot equipment, where the leads are has no
bearing on function.

c) Expensive - see a) above. From what I have seen here and elsewhere,
the higher the cost-per-watt of a SET design, the more pride its
designer takes in it.

d) Separate Supplies - see a) above.

e) Guitar Amp transformers would make common sense and as noted,
probably at a lower cost. See a) above.

Peter Wieck
Melrose Park, PA

[tubegarden]

Hi RATs!

Once again, disparaging thoughts about other people inspire vague
psychodramatic posts from really bored guys.

Sorry, I know nothing of electrical circuitry or acoustics, but, I
truly love to insult those people ...

****** is as ****** does, eh?

Happy Ears!
Al