Tube amp question (about output transformer)

[Coytee]

OK, we all know I'm a dummy so this is a very simple question.  I know there is probably a complex answer but for the sake of keeping it on my level, keep it simple.

 

If you have a tube amp (for my concerns, I don't care what type) it's generally going to have an output transformer hanging off the back.

 

My understanding is you can put transformers of varying quality on them.

 

Let's stipulate that the following are all of the same (good) quality....  I don't think this is an answer about quality of windings or anything...but rather size.

 

If you put to small of a transformer on an amp, I'm guessing that the signal can overwhelm the transformer and the sound will degrade (?)

 

If accurate, what happens if you go to the opposite extreme?  Again, roll with what might be absurd here for the sake of making it clear....  can you put a transformer onto a tube amp that is a "size 10" when the amp design might actually call for a transformer that is a "size 5"?

 

I understand that you probably want to size it properly....  so that's not allowed to be part of the answer!

 

 

I know I'm butchering the "size" of the transformer...but I don't know how to word it.

 

So, if you have an amp that best fits a "size 5" transformer, what happens if you instead, put a "size 1" verses a "size 10" on it?

 

 

[Rick J B]

Bigger the better.

[thebes]

I'm hardly an expert, but as I understand it output transformers are not readily interchangeable.

 

For tube transformers are designed to output different wattages (ie 15watts/40watts etc.) and to work with a certain type, or types of tubes.

 

Ie, a output transformers designed for use with an EL84 tube will not play well with a EL34 tube.

 

Also there basic differences.  Some OPT's are for SET output while others have the windings for Push/Pull.

 

So to  me size only matters if your dealing with the proper topology.

 

This is by noways a very good explanation, put posted as a placeholder until the experts properly explains it to you.

[Don Richard]

The primary windings of an output transformer are rated for current, voltage, and impedance. In other words, they are designed for certain tubes. The secondary windings are designed to feed certain load impedances. And what Thebes said about push-pull vs single ended.

[tube fanatic]

This is a very difficult question to answer without getting technical.  But, in general (and this is very general), you can always use a transformer of larger physical size in place of a smaller one.  As Don Richard said, current/voltage/impedance are the critical issues and as long as those values are what the tube requires (you can always use one rated for a higher voltage/current as long as the impedance is correct), you can use any transformer.  Take, for example, the Hammond 125SE series of transformers.  They are available with multiple ratings, and the physical size varies accordingly.  However, the frequency response of all is basically identical.  As far as overwhelming the transformer goes, that can occur if you exceed its wattage rating.  It doesn't mean that the transformer will burn out or cause any damage to the amp, but its distortion may increase to a level which makes listening objectionable. Hope this helps a little!

Maynard