Triode vs. Penthode operation

[newey]

As I consider dipping my toes into the water of "tube tone" and adding a low-wattage tube amp to the choices I have (which are all SS currently), I note that a large number of these smaller amps feature a "low power" setting, which in most case seems to be obtained vis switching the tubes from penthode operation to triode operation, which, in my limited understanding, basically halves the power output.

What none of the manufacturers seem to say is what my question is: Does switching the mode of operation affect the amp's tone, or just the output? And, if so, then how so?

Now, I know the "how so" question gets heavily into the subjective realm, but since I have no experience with these things, just generally, is there a difference and of what, generally, does it consist?

[Yew]

Now I havent played with the 15W setting of my Tiny Terror for ages, however I remember it seemed to be a bit Cleaner than the 7W setting and seemed to have a more rounded treble. Unfortunately in the immortal words of chrisk its 'not in this city' however Ill be back in Mansfield this weekend, So Ill go and give it a try and come back with some more 'tasting notes'

[ijustwannastrat]

Yew, are you testing the amp at the same settings? Or the same volume? Because the extra push you can get at 7W might be enough to give it a bit more grit. Just a possible variable...

[newey]

I appreciate the effort, Yew! Looking forward to your impressions.

As I look at these smaller tube heads, I have pretty much been assuming that all of these amps that have a "half-power" switch or whatever they are calling it are in fact switching from triode to penthode operation.

But what do I know? Is there another way to do it, or do I assume whenever I see one of these that's what's happening under the hood?

I had sort of assumed also that penthode would be "fuller" (or some such adjective).

I guess my main concern is, if I buy one mainly for home use, I'll probably be using it at half-power most of the time- but what if I don't fancy the tone in that mode? Will I end up with something that I only like when it's rattling the windows?

Of course, the short answer is to go out and play through one or more, but I may end up wanting a model not easily available locally and/or having to buy it on-line.

[jcgss77]

Hey newey & yew, I think that the switch simply removes/adds one of the EL84's in the ouput section. Looks like it is a push-pull configuration at full power, then switches to single-ended. I would think that when switched to low output, it would have more distortion than push-pull, as push-pull has a tendency to run cleaner than single ended, not to mention that you will have the amp cranked too!