Premium Vacuum Tubes

A: Answers to this question is related to your budget, as well your desire for the level of sound improvement.

The general rule of thumb is:

1) Upgrade the pre-amp tubes first. These are typically the smaller tubes at the front of an amplifier (power tubes are typically at back closer to power output transformers). A sound signal from your source component (such as CD player) is sent into the amp for amplification – preamp stage is first amplification stage so money spent on upgrading preamp stage tubes will give you great improvement. Garbage in, garbage out. If you don’t get great preamp signal, you won’t get great final output signal to speakers.

2) Once the signal being amplified at preamp stage, it is further amplified at the power tube stage. If your budget allows, get the power tubes upgrade to the extent that your wallet is happy and your ears are happy too. Most common power tubes are EL34, KT88, 300B and 845. The price for these tubes are in the same sequence from low to high.

3) There is no such a thing called ‘best sounding’ tubes. All such comments are in certain context – tubes should only be compared when everything else is equal, i.e. same room, same speakers, same source etc.. No two amp owners have exactly the same set up so all impressions you heard or read online is just for reference. Let your own ears be the judge for good sound and no one else.

Happy listening.

Rachel @ Grant Fidelity

A: No, not necessarily.

A tube tester uses a pre-built circuit to test a vacuum tube’s technical specs DURING THE TESTING PERIOD. Many factors come into play when the tester gives you a tube plate current result (in mA). This testing period typically last only a minute or two – some tester has pre-heat phase (such as Amplitrex has 60 seconds pre-heat on auto testing mode), others may not or the pre-heat period is too short to have the tubes emitting stable stream of electrons (current).

Tube is a live creature – when heated, it emits electrons and work in a circuit; when not heated enough, it will generate electrons but the quantity may fluctuate overtime then stabilize. A short testing in a tube tester will not definitely tell you if a tube is drifting (i.e. current keep changing) or not. Drifting is term used over extended period of usage time – not over a minute or two of testing in a tube tester, especially an old tube tester that hasn’t be calibrated for years with aged parts inside which could cause significant error in testing results generated.

You need to burn-in a tube over the manufacturer suggested time (Psvane tubes are recommended to burn-in for 150-300 hrs) then check it in an amp to see if the bias is drifting significantly or not (10-15% changes is not considered significant as many parts in an amplifier or electronic device has more than 10-15% variation from standard specification, and this range of variation will not do any harm to sound or equipment).

The bottom line is – do NOT become obsessed with numbers. Variation is expected when you have a piece of electronic device which is made with hundreds or thousands pieces of parts together. Unless the variation is statistically significant and you are seeing signs of problem on the playback device – i.e. amplifier  (such as overheated plate, distortion in sound, very noticeable noise through speakers etc), enjoy the tunes. When significant issue arise, contact us – we always stand behind our warranty 100%.