Calling All Tube Gurus

@elrod 

The good and the bad of using tubes is there a lot variation.  The biggest variables are brand and how much they’ve been used.  If you have a decent system and decent ears, you should be able to hear the differences. Recently I bought some used PS Audio hybrid gear.  The preamp came with PSVANE tubes and two extra sets. When 5 out of the 6 tubes that came with it started making a clicking noise and PSVANE would NOT help, even though they knew they put out a bad batch of tubes, I was forced to start tube rolling a bit sooner than I hoped.  I Bought some Tung Sol’s, some Genalex and some RCA tubes.  All three sets sounded different. One had better bass. One had a better high end and I have found that the RCA Cleartops sounded the best to me.  The reason I told the story was, try to imagine that you had two different brands in each channel or one new tube in the right channel and one well used tube in the left channel. The two channels would not sound the same.

Oh and I will never buy PSVANE tubes ever again!!

All the best.

Hello All!  When it comes to 12AX7s, the NOS Telefunkens can't be beat, unfortuntely that makes them pricey. I was very surprised, pleasantly, when I put one in my Elekit 8600. Victor Kung, the distributor for Elekit, was kind enough to send me one and it is terriffic!  Thanks, Victor!  Happy Listning.

I find enjoyment and value in tubes made for hospital equipment. Often these have red, blue, or yellow painted tips . In most cases, these have been screened for critical use.. I find most of the red, yellow, and blue tips incredibly quiet and very three dimensional in sound. Sometimes they were made by Amperex, or Telefiunken, Mullard or even Matsushita but released under a different brand.. I generally feel the same about organ tubes (Baldwin, Wurlitzer, etc) often made by RCA that have gone through the extra screening process to assure low noise..

If the tubes were made with acid etched codes as were all the Philips Europe tubes then the code is all that matters. Same can be said of the silk screened codes, but they can be more easily faked and often rub off. Branding has no influence on the quality of the tubes. This is especially true of the major electronic companies like Magnavox or Philco. A rebranded Amperex made Mulllard is just as good at the Amperex branded tube. If it is a rebranded like National, I guess it is possible that these could be rejects.

I have experienced differences in sound from the same tube with different production dates from the same mfgr. I would attempt to get identical or very close production dates especially in high quality 2 channel applications. 

In closing look to things like the Telefunken diamond, acid etched codes, tube seams or top dimples when buying old stock tubes. Look for things that are difficult to duplicate. One more thing that buyers seem to get hung up on is the quality of the tube lettering. On many tubes, the lettering can be easily rubbed away. What you dont want to see is the lettering that wont wipe off easily. If the lettering is fixed or yellowed this tube has most likely seen heat.

I'm currently running two different branded NOS 2a3 tubes in my Wright monos matched by Tube Depot. One is GE the other is Raytheon I believe and they sound fantastic.