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Tubes to Watts Ratio

I own a pair of great sounding Quicksilver M60s that produce 60W per side using 4 EL34s per side (PP configuration). These amps also have what appear to be pretty serious power supplies, as both transformers are no joke. I've noticed that most PP amps with this many tubes per channel and this kind of iron produce anywhere from 20-40 more watts. Does anyone know why such a design would not pump out a bit more juice?
bojack

Showing 2 responses by atmasphere

atmasphere's avatar
atmasphere
12,116 posts
 
Bojack, just to be clear, the proper term is 'self bias'. Self bias gets the bias for the power tube by dropping a voltage across the cathode resistor of the power tube.

An autobias circuit does not do that. All autobias circuits generally fall into the category of 'fixed bias' which is to say that something other than the current through the power tube is fixing the bias. It might be manual, and it might be autobias, but either way its considered 'fixed bias'.

IOW, the Quicksilver is *not* an autobias amplifier.
atmasphere's avatar
atmasphere
12,116 posts
 
There are a variety of factors that govern the size of transformers. In power transformers, temperature rise can be a big factor- transformers that don't get as hot tend to be larger.

In output transformers, the amount of bandwidth that the transformer has on the low end has an effect on the size, as does the power that the transformer can deliver. If the transformer is set up in a class A amplifier, it might be a bit larger as well.

This is all general...YMMV
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