Calling All Tube Gurus

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.