Matching Tubes

[astoria]

How much does "matching" tubes matter, if at all, in the dual tube pedals like the Black Eye and Ambassador?

 

[Mentaltossflycoon]

I plunked what came in the mail into my black eye and it's awesome.

 

[Alan W]

It’s gonna depend on the circuit design of the pedal. My guess, is that in general it won’t make any difference with most tube pedals. You can always try switching their positions, too. So if one tube is a bit hotter than the other, you might get ealier or later breakup, that sort of thing.

 

[vigilante398]

It absolutely does not matter at all in preamps. The stages of the tubes are all in series, so if theu aren't matched it just means some stages might have slightly different gain than others. This is a personal choice based on what sounds good to you, but I've had some people go so far as to use a 12AT7 and a 12AX7. For different amounts of gain in different spots in the circuit.

Matching power tubes in push-pull (class AB) amps is important so you don't have tubes with different characteristics doing different amounts of work, it stresses one tube more than the other. But in a class A amp or in a preamp where everything is all in series, it doesn't matter at all.

 

[RetiredUnit1]

Preamp tubes in general are not matched. It's a lot less important in a cathode based bias scheme. In power tubes that are cathode bias same deal. Matched bias becomes important in what is known as fixed bias (which is a misnomer because it's adjustable, but I digress). In this system a "fixed" negative polarity is adjusted in voltage until the tubes are operating at about 70% of it's rated potential.

I like to use TWO bias pots at the end of the phase inverter so I don't really have to worry about if I can find a matched pair of tubes.

 

[astoria]

It absolutely does not matter at all in preamps. The stages of the tubes are all in series, so if theu aren't matched it just means some stages might have slightly different gain than others. This is a personal choice based on what sounds good to you, but I've had some people go so far as to use a 12AT7 and a 12AX7. For different amounts of gain in different spots in the circuit.

Matching power tubes in push-pull (class AB) amps is important so you don't have tubes with different characteristics doing different amounts of work, it stresses one tube more than the other. But in a class A amp or in a preamp where everything is all in series, it doesn't matter at all.

Awesome thanks! This is what I thought but am still new to the whole tube world and was wondering if I was missing something