Preamp tubes in guitar amplifiers

Posted by Edwin Van Bunderen on

Let us talk preamp tubes !

There are quite a lot of different ones : 12AT7, 12AY7, 12AU7, 12AX7WA, 12AX7WB, ECC83, EF806, 5751, 7025, … And different brands. Made in Eastern Europe, Russia, China, … New Old Stock are very old tubes previously made in Germany, U.S.A., …

All of them are selected tubes, not standard. All of them are double triodes, so you can think of them like a double shot gun : they have two sides doing the same thing. Indeed a 4 tube preamp actually is 8 half tubes …

These different tubes have different outputs and functions, so you would have to match them to your individual needs ...

Some tubes are used to raise the volume of a signal, others to add distortion, compression or simply phase inverters.

Some tubes need to be internally matched : especially phase inverter tubes ! They need to precisely and equally divide signal to all power amp tubes.

When you buy matched preamp tubes, it means that both half of the tubes have ‘exactly’ the same values. Yes, of course they are more expensive than standard tubes.

Hope to have enlightened some of you …

Get your tube amp checked at groove Street 98 !


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