Site Updated: March 5, 2008

Frequently asked questions (and their answers) :

How can you get only 25 watts from a pair of EL34s? Aren't they 50 watt tubes?

This is something that far too many people are confused and misinformed about. The tubes themselves don't set the
maximum output power of the amp - the transformers do. The tubes can be thought of as the middle men between the
power transformer and the output transformer. They move power from one into the other as much as they can.

The following are some examples that can help you understand all this technical stuff.

Please note that most amps do not have sufficient heater current available to safely heat tubes with more hungry heaters
than the amp was designed for. There may also be other issues which are not mentioned here. Contact the maker of your
amp or contact us - we'll be happy to discuss power tube substitutions with you.

25W amps with EL34s or other "big" tubes:
If the transformers are designed for 25W and you replace the existing tubes (say 6V6s) w/ larger tubes you will still only
get 25W. That is all the power available TO the tubes.

100W amp w/ two of four tubes removed:
If you have a 100W amp with four power tubes and you remove a pair, the two remaining tubes can still only move enough
power from the power supply to the output transformer to safely provide 50W.

25W amp w/ two tubes added to the existing two:
If you have a 25W amp with two power tubes and you wire-up another pair of power tubes (ignoring the other technical
aspects of doing this) you will still get 25W maximum but the tone will be different - much more "effortless" and "open". Now that there
are four tubes doing the job that two tubes can safely due, the work load on each tube is less now and the tubes will probably
last longer.

Special case - replacing large tubes (eg. 6L6s) with 6V6s:
In many larger Fender style amps it is safe to replace the existing 6L6 power tubes with 6V6s for less maximum power and
less headroom without any modifications. In this case the power tubes do limit the maximum output of the amp.
6V6s have lower transconductance than it's larger counterparts - think of them as being lazy. They can only move as much
as they feel like moving even though there is more work that could be done. There is a Fender Twin running with four 6V6s instead
of the stock 6L6s for about 40W output that we modified for a customer years ago - it's still running wonderfully well and has some
great dirty blues tones coming from it every single week. There power transformer is also running cooler due to less draw on the
heater and plate windings which will extend it's life.

more to come...

ph: (519) 913-1299

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London, Ontario CANADA