6V6 Tube Review
Current production 6V6 tube information. Updated July 31, 2017
I've been experimenting for years working to find the right mix of good sounding and reliable 6V6 tubes to stock here at the shop. After installing thousands of tubes, here are my two top picks and why.
Top Pick – 6V6GTSTR from Ruby – Recent testing at our shop has revealed this tube to be the most well built, rugged and consistent 6V6 in production. Batch after batch provides full power output and there is very little variation between tubes or plate current ratings. This tube has more highs and lows than the JJ whereas the JJ has a more midrange focus. Although the highs can get a little harsh in some amps, adjustments can be made to dial in a great tone.
Second Choice – 6V6S from JJ. This is generally a reliable tube. Although the tone is not really true to the 6V6 standard, it is still a good sounding tube. Its voice is a little stronger in the midrange with a little more aggressive overall. Power output is few watts lower than some others but the perceived volume is not redically different. It's a good choice when a little more midrange grind and good reliability are needed. There are two disadvantages to this tube. 1) Mechanical rattle is a common complaint. 2) The output is a few watts lower than others. Because of these factors, this tube is being phased out in favor of the Ruby (see below) for our standard for use in repairs and in our own Andrews Amps.
Coming in at #3 – 6V6GT from Electro-Harmonix. A number of years ago this was the first good-sounding, well-built 6V6 tube to arrive on the scene after several years of living with not-so-great choices. It's based on the RCA type and it does of good job of looking and sometimes sounding like the vintage tube. A good pair of these tubes will provide superior tone to any other 6V6 available (matching the Tung Sol). The overdrive is very smooth and "creamy" with a soft feel. Great for harsh sounding amps or speakers. Although the reliability of this tube is generally quite good, we have been having a very difficult time getting good ones from the factory. Reading reviews of this tube on various forums and tube sellers web sites reveals a wide range of opinions. I've been puzzled by some of the negative remarks made by some about this tube and I've done some research to find out about this disparity of reviews. Over a period of several months, I ordered two fairly large batches of these tube directly from the manufacturer and did some comparative testing. I have found that a stunningly large percentage of these tubes do not meet specifications. Specifically, they will not produce anywhere near the rated output power of the amp and tube. After testing all the tubes on a Hickok tester and then on my custom built tube matcher, I set up a Deluxe Reverb amp for looking at and measuring the output waveform. The amp is rated at 22 watts RMS. The majority of the tubes in the first batch had a great waveform and produced 20 to 23 watts before clipping and sounded excellent. However, almost 30% of this group produced less than 18 watts and showed a distorted waveform and terrible tone. Some of the pairs produced under 10 watts! Of the second batch, none of the tubes could meet specs. Again, some pairs not even making 10 watts. I have returned the bad tubes and we are no longer ordering these tubes.
Last choice – Tung-Sol 6V6. Physically, this tube
appears almost identical to the Electro-Harmonix variety and it's
built at the same factory. The internal parts are the tube are moved
up higher in the glass bottle. The bottom mica wafer has a different
shape and the getter (the part of the tube that sprays the silver
coating onto the glass) has a different shape and is moved to the
bottom of the tube. Neither of those components affect the tone or
reliability of the tube. I realize that there is much talk around
the internet by people who prefer the TS or the EH tube over the
other choice but as many time as I have listened to them, I have yet
to hear any difference more that what I would hear between two pairs
of the same brand. I suspect these are functionally identical tubes
although I have no direct proof. I have also not seen any difference
in reliability between the two. Therefore, I rate the Tung-Sol last
because it has a higher price tag without bringing any extra
benefits. Note: Some of the EH 6V6 tubes mentioned in the above test
appeared to be Tung-Sol tubes with EH labels. Not recommended!
Note about Grove Tubes 6V6 – GT markets the tubes on this list with their brand name on the tube and a higher price tag. Hopefully their testing is good enough to weed out the bad ones. We prefer to do our own testing and keep our prices as low as possible.