Dating vacuum tubes, vacuum tubes

Typically, European codes are printed a chalky, easily rubbed off type of paint towards the bottom of the tube near the pins. Since Mu is what controls voltage gain, and voltage gain is what we listen to, then lets measure that directly. It was in the interest of companies like DuMont, Admiral, Emerson etc to have their own logos on the tubes that they supplied in their equipment. How these measurements are applied and their relevance differs for triodes and pentodes.

Vacuum tubes

There is much confusion in the audiophile community about these factors as they affect tubes and their performance in components. There is no assurance that these tubes will have equal voltage gain. If you find the tube in North America, assume the European code is correct. All you need to do is monitor the condition on the cathode coating, which is easily measured via emission. They will allow for more playing time with rich, well defined tube tone.

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All we are concerned with here is the Manufacturer code. Norma likes the first date sex! The filament is used to provide the heat necessary to release electrons from the cathode. We will also look at tube testing, tube matching and which characteristics are most important when matching tubes for a given circuit. If the grid is made less negative, the number of electrons passing through the grid increases.

No commercial tester ever measured Mu either. There were a few different reasons a given company would re-brand or write the wrong country of origin on a tube. Let's look at some of the basics of how tubes work to have a better understanding of the benefits of using matched tubes versus unmatched power tubes in a guitar amp. It puts you in control of your tone. Only Sylvania and National Union had the equipment to make them.

For Pentodes, as used in our power amp output stages, Gm does indeed matter and must be matched for good performance. Why then do most vendors measure Gm and Gm alone? Given that, all we need to measure is the emission to know the tube is still good.

Identifying Vintage NOS Vacuum Tubes by Brand Country and EIA Code

Since electrons have a negative charge, the plate is given a positive voltage to attract them. They had a contract with a large company to print their logos on the tubes. The control grid is placed between the cathode and plate and is given a negative voltage to repel electrons and restrict their flow to the plate. Depending on where it was made, you there are different clues to look for.

If Gm, Rp and Mu are right and matched when new, they will stay right and matched through the usable life. For a more technical explanation of why we match tubes, click here. Many tubes have a printed country of origin on them. Of course we had to build our own tester to do that. Here, Mu voltage gain is the more important parameter to measure and most directly affects what you hear.

Why Should I Match My Tubes

They are simple to use, stable, accurate and relate well to the life remaining in your tubes. Rp or plate resistance is the second most important parameter as it directly affects the output impedance of the preamp. So what's transconductance?

Identifying Vintage NOS Vacuum Tubes by Brand Country and EIA Code

Email tubeaudiostore gmail. Written by world-renowned amplifier, Roger Modjeski, this article, will look at what each of these characteristics mean, watford hospital dating how they are measured and what each of them means to the sound of a component. The tube with more plate current will be dissipating more power and getting hotter than the tube with less plate current. If they could source the tubes cheaper than they could manufacture them. Only in rare cases will this not be true.

Henessy is busy updating her dating profile. Vacuum tubes were simply a commodity that everyone needed like batteries or light bulbs are today. There are many brands out there that never manufactured their own tubes.

Dating vacuum tubes
  1. Which is part of the reason it can be so hard to figure out today.
  2. Matching the plate current and transconductance allows you to set the bias with maximum precision for that optimal sweet spot where the tubes will sound their best and won't burn out early.
  3. Gm is the thing to measure here but the Hickok does not measure anywhere near the real world operating voltages and currents found in a typical circuit.
  4. Why does this difference in idle plate current matter?
Dating vacuum tubes
Dating vacuum tubes
Dating vacuum tubes

This is a dangerous situation as many of you are buying because the vendor says it is matched, though it may or may not be matched for something unimportant while something important is not matched. Here is a list of European factory codes courtasy of audiotubes. These parameters are locked into a relationship so that knowing any two will yield the third. So if Gm is matched to, dating get matched Mu the important characteristic in this circuit Rp must be matched also and Rp is almost never measured. Triodes are most widely used for voltage amplification in our preamps.

Antique Radio Forums View topic - Sylvania Vacuum Tube Date Codes

If you see this type of getter, there is no doubt it's a less valuable Russian tube even if it's a Telefunken labeled West Germany. Photography by VisionQuest Photography. Therefore, gain is Gm times the load impedance presented to the tube through the output transformer. If two tubes are biased for the same amount of idle plate current, but provide different amounts of amplification, are they truly matched? They want everything to be matched, message though they rarely know what it should be matched for.

They ran out of stock of one particular type and contracted another company to make them to fulfill an order. However what is important in triodes is Mu and what is important in pentodes is Gm as these parameters are the dominant characteristics affecting performance when each is used in a typical circuit. As noted before, European tube print was made with a chalky substance and is easily identifiable and rubbed off. Matching comes into play because tubes vary in the amount of plate current flowing through them when given the same control grid and plate voltages. European codes can be a bit more difficult to decipher.

Once you've seen this type of paint it's easy to spot. To avoid a situation where the idle plate current is matched at one bias setting, top gamer dating sites but unmatched at another. There were many trade sanctions due to the various wars that went on while tubes were still being produced in bulk. Setting the bias involves finding a bias point where the amp sounds the best and the tubes are not overheating. Triodes Triodes have an interesting relationship where two parameters relate to make a third.

Often, the printed brand or printed country is incorrect. This is important for two reasons. Plate dissipation is calculated by multiplying the plate current by the plate voltage.

  • Buy your tubes from someone who certifies their specs to be proper when new.
  • If the grid is made more negative, the number of electrons passing through the grid is reduced.
  • The manufacturer sold in bulk to a wholesaler or distributor that marketed the tubes differently for a profit.
  • When trying to identify a tube it makes the most sense to first determine where it was made.
  • Once you know where it was made, that narrows down the possible manufacturers by a lot.

If the vendor measuring Gm would give you the Rp then you could calculate the Mu by simple multiplication. In many cases this is incorrect. If the bias pot is set too hot, the tube will be overheating and the sound can be lacking in definition.

Dating vacuum tubes

Tube Matching Demystified

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