Tube Help 6V6 NOS - Where To Buy?

RJLII said:

Yes, I cited those to him specifically. He told me these were not suitable for the high (430) plate voltages in my 5F10 Circuit Victoria Ivy League. Truth? Attempt at upsell? Who knows? The guy has some street cred so I'll take him at his word and stick with what's working for me.

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RJLII said:

Yes, I cited those to him specifically. He told me these were not suitable for the high (430) plate voltages in my 5F10 Circuit Victoria Ivy League. Truth? Attempt at upsell? Who knows? The guy has some street cred so I'll take him at his word and stick with what's working for me.

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Diablo1 said:

I've read that the Ivy League has around 400 volts on the plates with a 5Y3 rectifier, which is a lot higher than the Fender Harvard. However, Fender Deluxe Reverbs call out 415 volts on the schematic and would be higher with modern wall voltage. All those survived fine using good old american 6V6GT tubes. Bottom line is that 420 volts on the plate won't kill any NOS 6V6GT if biased reasonably so that the dissipation isn't too hot.

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sonar said:

I agree 100% about the NOS taking the voltages, but 430 volts on an authentic 6V6 tweed design?

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Diablo1 said:

Apparently the Victoria voltage is not so tweed authentic?
The Fender Harvard schematic shows around 305 volts on the plates.

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BIG Dave said:

Agreed. But I seem to be able to find NOS Mullard 12AX7A on ebay at reasonable prices. The trick is to forget about getting the 'Mullard' labeled ones and get the relabeled ones. A couple weeks ago I scored a strong NOS Mullard 12AX7A (ecc83) for just $65. It was relabeled 'GE' in the original GE box. As long as the right codes are etched into the glass, it's a real Mullard. Here is what I look for when searching for Mullard 12AX7A (ecc83) tubes:

* I61 code etched into the side of the glass. Under the 'I61' code will be four characters beginning with the letter 'B'. The B refers to Blackburn where the great Mullard tubes were produced. If there is no B, then it wasn't produced at Blackburn in Lancashire, England. Following the B will be a number which is the last number of the year (a 2 would refer to 1962). The next character is a letter denoting the month (A = Jan, B = Feb, etc) and the last character is a number denoting the week of the month (1 - 5). An example would be B1F3 which is a Blackburn tube, produced in 1961, June, 3rd week of the month. The I61 tubes were produced from 1959 to early 1964.

* I62 - These were only produced for a couple months in early 1964. You'll probably never see one so let's not worry about it and move on to the I63.

* I63 are the other Mullard ecc83 tubes I look for. These need to have the same four digit coding as the I61 tubes. The I63 tubes were produced from early 1964 through the 70's. Here's something to note, suppose you have a tube marked (for example) B4L2. We know it's a Blackburn tube by the letter 'B', and we know it was produced the 2nd week of December, but how do you know if it was produced in 1964 or 1974? If you look inside the top of the top, you will be see a ring (known as the 'Halo Getter') welded to a support rod. If the support rod is straight, the tube is 1969 or prior, if the rod is bent, it's 1969 or newer. But I don't get hung up on if it's a 60's or 70's tube, as they're all great and blows anything made today out of the water!

In summary, if you're looking for real Blackburn-made Mullard ecc83 tubes, look for the etched I61, I62 or I63 code, as well as the 'B' at the beginning of the four character code below the "I6x" code. And make sure they are tested strong on a good tube tester. I don't even consider the Mullard labeled ones any more because the price on those have become ridiculous, you're only paying for some ink. I don't care if it says GE, or RCA, or John Doe Tubes, as long as it has the right codes, it's the real thing.

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jcs said:

I personally screen all of my old production USA 6V6 with 3 teaters first but then they MUST pass a live test in my 65 Princeton which has plate volts around 450 range.

The bias/current draw has to remain stable and i use a minimum of 20 minutes per tube with a Bias Rite.

Btw, i rarely if ever find faulty USA 6V6 in terms of unstable current draw or shorts, most are just worn more than others with thinner getter flashing etc.

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