Tube matching/testing?

[DonBattles]

I would like to ask opinions about tube testing. Several vendors such as The Tube Store and Tube Depot offer various testing & matching for tubes. Examples are:

Matched sections
Hi Gain
Matching
Balanced Triodes
Matched + Balanced Triodes
Low Noise and Microphonics

From the list I gather that the Matched and Balanced would be the preference but Low Noise would be important also, especially in a phono stage (please correct me if I'm wrong). I have a tube preamp and amp and don't want to waste money on tests with no benefit in my applications.

 

[gogofast]

all those terms are somewhat related. "matching" and "balanced" means pretty much same thing. "balanced triode" here is probably referring to each section of preamp tubes such as 12ax7 which has two sections of plate, grid, cathode (triode) being matched.

balancing the gain of each section is pretty much what "matching" of preamp tube is, and it is important since you want both channel to have same gain and characteristics. yes, low noise/ microphonic testing is quite important in preamp tubes. even some of the most premium tubes have microphonic problems.

the question here is not if it's important and worth it, but how accurately they do it.

 

[becketma]

If you are going to buy current production tubes, try Jim McShane. He can probably make good suggestions for tubes and if you need phono "grade" or closely matched triodes within the tubes.

Matched can simply mean the same construction, the same model number for the tube.
Best
Bob

 

[BinaryMike]

I have a tube preamp and amp and don't want to waste money on tests with no benefit in my applications.

If your power amp has a full set of DC bias and AC balance pots, then you don't need matched power tubes. AC balance pots are not common, but are easily added. The problem is that you need a way to optimize the setting. Some sort of ad hoc distortion analyzer would be convenient!