Calling All Tube Gurus

Everyone?

If they want to contribute in a positive way (sad I had to say that)

Ideally you want the same brand tube. I wouldn’t take a chance with different branding. But, the most import would be the matching.

Are rejected tubes resold? Yes.

I find it hard to believe that Siemens would intentionally make inferior tubes for Amperex, or vice versa. It’s an impossible concept. I have Valvos made by Amperex, and British Brimars made for German Lorenz with the German military hawk symbol on them. They work great.

Of course, we want our tubes to have matching codes, and names, but these days it’s becoming increasingly difficult to find. However, if they were made at the same factory within, say, a couple of years and have the same construction, I wouldn’t mind buying them even if they have different labels—as long as they’re matched, of course. In my experience, the sound will be indistinguishable from the originals.

@russ69 the only way to accurately match tubes is to match them in the circuit they are to be used in.

Here is a paragraph from Joe's Tube Lore. See if this is helpful information. For details, check the link.

Be careful of getting hung up on the brand name printed on the tube. In my experience most Siemens 6DJ8 family tubes you will find in the US are labeled anything but Siemens. Why? Siemens (and most other manufacturers) served as an OEM (original equipment manufacturer) supplying their tubes to many other tube manufacturers. While Siemens made these tubes they were labeled with the name of the company they were supplied to RCA or Phillips for example. Now not all RCAs and Phillips were supplied by Siemens, so that’s where points 1 5 on how to check tubes comes into play. Fortunately, in many cases the tubes are labeled with the county of origin & that can help you identify a tube’s manufacturer. Made in West Germany? It’s usually a Siemens. Made in Holland? Probably an Amperex. Made in the USA? Usually a Sylvania or an Amperex. Oh yeah a useful tip: RCA never made 6DJ8 family tubes. If it’s an RCA and has a ridged top it’s either an Amperex or a Siemens. I’d watch this brand closely if you stumble on it. Many tube dealers will sell lowly RCA 6DJ8 family tubes for $15 to $20 a tube without realizing that there is European made gold inside. Check the tube’s top for ridges, the label for where it was manufactured and if everything checks out, buy it! This is one of the absolute bargain brands in this tube type.

Amperexes were also frequently OEM’d to a variety of manufacturers. Most commonly to Mullard, DuMont, Beckman, Hewlett Packard and a few others. The risk with Amperexes is that they do vary by vintage and model and it’s hard enough to keep that straight among Amperex labeled tubes. Which vintage / version are you buying under another manufacturers brand? Who knows? It’s just pot luck.

https://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html

Anybody know who makes McIntosh branded tubes?

To your date code question: I think it's not really relevant as tubes from the same batch can vary by a LOT.  I read that manufacturers think 5% variance is fine. Try 5% louder in your left channel and me that me 5% is fine. :)

I once replaced a pair of Sovtek 6550s that were damaged by red plating. I bought NOS Sovteks that were matched. Popped them in and viola! Louder on the left. Another tube- a Sylvania BH7A was causing the red plating. I replaced it with NOS. Soon after the right channel BH7A started acting up.  I realized that the best practices way to have avoided all this wasted time and money was to buy a whole tube set already matched from my manufacturer. "Your first loss is your least loss" 

I don’t mean to derail this in any way but wanted to add my experience. In the pursuit of better sound we search out tubes,sometimes based on some thing we read like "Joe’s tube lore".Why Not ? It’s a fun and informative read. But these and similar reviews/comparisons, although meticulously done, might only have used a single example of a given tube. Someone like Joe, came to these conclusions within the context of his system, preferences, and gear that  was posted on the asylum 25 year ago. Much has changed since then including equipment and tube supply.

Tubes can vary, time and usage takes it’s toll if the tube is not New Old Stock. I trust the opinions of the best tube resellers like Brent Jesse. They have experience with multiple examples of a given tube over time and have a reputation/business to maintain..

One can generalize that performance will be similar over many years of a tube’s run if the internals look the same and that may be more important than getting stuck on a specific date.

I’ve bought supposed "Holy Grail" tubes that have "underperformed" my expectations.

I’ve bought tubes that are not the same date codes as the recommended ones that sound as good because they are the identical construction. Buying old tubes is a bit of mine field but So worth it when you do find the gems.

Case in point I recently bought some Matsushita tubes.When Mullard closed down Matsushitu bought the tooling from them and continued to make them in the meticulous way the Japanese do. The resulting tube is sonically equal to the equivalent Mullards I have and were a fraction of the price and easy to find New Old Stock

I have Audio Research components and purchase my replacement tubes from them. All I know for sure is that they are very, very picky about their tubes and reject a large percentage of them.

Alvinnir2,

Very good observations/advice.  Some people get a bit too obsessed with matching.  A local dealer has a huge collection of used tubes that still test very strong and he "matches" them by finding tubes with the same internal structure.  That is it. 

I am "blessed" with running such rare and exotic tubes that there is no issue about matching; if they work that is as close to matching as I will get (I run 310, 311, 348, and 349 tubes).  If I ran more conventional tubes, I still would not go crazy with matching.  I could do matching the right way if I wanted to using something like the Amplitrex tube tester which can, if hooked to a computer, curve-trace the tube.  That really is the best way to match tubes, but it takes a lot of experience.  I can read the curves and I know what they show, but, I have no idea what is good enough or what is a close match.

"If you can determine that a tube was made in the same plant, has the same construction and date codes, how critical is it if the tube was made by Siemens and rebranded as an Amperex? "

only critical to appearance if appearance is critical

"I’ve heard people say that if a manufactures tubes are not up to their standards, THOSE are the tubes they send out to the other manufactures for their branding. Fact or fiction?"

nonsense AND fiction. 

tubes are identified by and perform/sound similarly according to manufacture. rebrand is only as important as looks. even within one production run they vary in quality.

"matched," unless qualified by "gain matched" or mention of emmisions testing, refers to tubes of the same manufacture and contsruction testing within 5-7% plate current at spec voltage (power tubes) or 7-10% transconductance (preamp tubes) or both.

as far as branding/label, if you want them to look the same then hey it looks good. what someone writes on the outside doesnt alter origin, identity, sound or performance, nor does it opertain to matching.

Even on the same tube type, factories tweaked their construction from year to year. Usually to save money. Some of these changes are visible, others may not be?

Anyways, we (I mean the collective "we" here, including me) probably let our audiophile nervosa run rampant too much. I've used pairs a tubes a few years apart with different internal construction.

Example 1: GE 3-mica black plate 5751 from the 1950s, but one from 1953 with the "silver clips" and the other not (from a few years later) - and honestly it sounded great (Rogue Apollo tube monos). The "silver clips" was the better tube but enough of its magic came through without an obvious asymmetry here. Of course I ended up getting more (many more) of the silver clips version for symmetry and peace of mind anymore. But if you've got a factory match, "similar" construction, and a good electrical match, it should be fine.

Example 2: Brent Jesse might even slip you a slightly construction mismatch if you're not careful. I got a pair of Mazda 12AX7 from him, one with shiny silver plates (the typical kind for this version) and one with matte silver plates and a different hole arrangement. They actually sound just as good as any other pair of shiny plates I've got, so I kept them. 

Example 3: I also like the fabled Tung Sol round plate black glass 6SN7, but it's hard to find tubes that are strong. The heaters on these also commonly die (even if they tested good). So I've ended up now with a pair in my amp where one has the oval-mica construction and the other has round mica. Sounds great, no problems!

Mac new branded tubes are JJ’s. Not the best but reliable and available. 

First let me say, I’m certainly not an expert. I’ve owned a CJ amp for the past 13 years. After talking to a number of very experienced CJ owners with a plethora of institutional knowledge on the CJ owners group, I switched to matched tubes several years ago. All four of the output tubes on my amp are matched even though they are individually biased. I also matched the signal tubes. If you are interested in purchasing matched tubes, it’s important to purchase tubes from a reputable supplier with all the required equipment to properly test and match tubes. Kevin at Upscale Audio is a reliable source in the USA. However, his prices are a little higher and most come with a guarantee. Rolling tubes can get expensive. I’ve found talking to people that own or have owned the same equipment for an extended period of time to be the most helpful and reliable. In the end, only you can determine if the added cost of matched tubes make a sonic difference in your system. Luckily in my case, CJ has an online owners group that is extremely helpful. Again, a number of non judgmental people with a lot of institutional knowledge and experience. I’ve never run across a rude or condescending person on the CJ forum. Hope this helps. 

Back in the day when tube everything was more common, when a tube went out we would search Dad's tube drawer for one that was the same size and number of pins and replace it.  The biggest concern was trying not to too badly burn your fingers finding which one blew.  Seemed that whatever you dropped in sounded fine. Really just happy to get it working again to keep listening to the music. 

You should contact Brent Jessee at 847-496-4546. He know everything about tubes and is awesome to work with.  Here is his website.

www.audiotubes.com

Sophia Electric

@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.

"NOS" means new old stock which indicates never used except for testing. Many of the tubes you refer to as NOS may just be old stock. True NOS without original boxes are uncommon.