tube tweaking amplifier dean farley signal cahin

Dean Farley talks tweaking tubes for your desired tone.

Hello, everyone. I know some of you will think I’ve gone crazy once again, but since this column deals with unorthodox ideas and methods of finding tone in any part of your signal chain, this sort of thing will be standard fare. Did you know that guitar amplifiers have a preference in which way the power (or output) tubes are installed? By this I mean that the tubes will sound better when you find the right order, meaning simply which tube is installed in the first socket, the second socket (and so on).

When dealing with single-ended, Class A amplifiers—a single output tube amp such as the Fender Champ, for instance—it is a very simple matter of experimenting with different brands of output tubes to find which one really rocks your world. I recently re-voiced a brand new Fender Champion 600 by taking out the stock Chinese 6V6 and replacing it with an NOS Tung-Sol unit from the mid-fifties. You should hear it now! It has this buttery, rich sound that makes the Chinese tube turn green with envy. No contest here whatsoever! This $200 amplifier has turned out to be one of my favorite recording (and practicing) tools. Even late at night I can achieve some ripping tones with this little monster. Recorded right, it’s downright amazing to hear.

Back in the early nineties I had an opportunity to visit Trainwreck Circuits’ Ken Fischer at his home in New Jersey. When I came down the stairs into his workshop, he was in the middle of finishing up an amplifier. After briefly showing it to me, he started to listen to the amp once again, just for a quick moment, then turned the standby switch to its off position. Beside the amp was an oven mitt he could wear while he changed the position of the still-hot power tubes. He repeated this ritual a couple of times until he enthusiastically proclaimed, “That’s it! That’s where the amp likes the tubes the best!” Needless to say, I was taken aback by the whole concept; at the time I did not know that tube order really mattered. But what happened to me that day was that I could easily hear what was going on, and at the same time understand the reason why. In the ensuing years I made many mini-discoveries about guitar and amplifier tones. I soon realized that all this minutiae also has a big effect on how you play, with even the smallest changes in anything based on tone or feel. Yes, these small details will indeed affect your style, and your performance as well.

Now, as we go further up in wattage, we have more to experiment with. For example, if you use an amplifier like a Komet 60-watt head, or a 50-watt Marshall head, these amplifiers are very sensitive to tube order and tube type. In the Komet 60 head you’re able to use not only a bunch of different types of output tube (EL34, 5881, 6L6, or 6CA7 just to name a few), but you can ultimately decide how you like the the amp’s sound according to tube order—simply by switching the position of the two power tubes. Keep in mind that you can also experiment with different tube brands. Each brand will have a unique tonal signature!

You can easily hear and feel these differences as you experiment with them. If you’re new to this type of tweaking, it’s always a good idea to record each variation you come across (or do some quick A/B testing afterwards), so your ear will not forget the new sounds you’ve discovered during the process of experimentation. Sometimes the tonal shift will be large, while other times the differences will appear to be more subtle. But don’t let the subtleties fool you! This is where you can really dial in the tonal nirvana you’ve been looking for. With a bit of patience—and an oven mitt ready—you can have a lot of fun learning about tone and how it affects you, the player.

I have an entire tablet devoted exclusively to documenting exactly which tubes work well in my Komet 60 head. This is a culmination of eight years of me tweaking only power tubes (brands, types and tube order in the amp). I also included in my notes exactly where the bias points are set for each tube combination. This is a great thing to have in your gig bag if you need to change tubes on the fly, such as when a power tube blows up in the middle of a set. Here, there is no guessing at all, because all the details have been sorted out well ahead of time. I can be up and running in just a minute or two, using a small Mag-Lite flashlight. In case you’re wondering, there is only one amplifier in my collection that is bone-stock. All of the rest have had a tube changed here or there, to suit the occasion.

Last, remember that if you’re experimenting with a 100-watt (or more) amplifier, with four power tubes, there are 24 possible combinations of where you can position the tubes! Sounds fun, huh? Until next month, I suggest that you buy yourself a standard yellow-lined writing tablet and get to work finding your own tone. See you next time.

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