Voici ce qu'on trouve sur le site de Jacmusic, à propos du Platinum Matching, ça peut expliquer pas mal de choses :
jacmusic.com a écrit :
WARNING. The PL matching is a special manufacturer's process, which costs a dealer a lot more to buy those. Don't let anyone sell you "PL" tubes that they match themself. These are no factory matched PL.
A "PL" pair, quad or octett, is stabile right from the beginning, all values on the boxes are IDENTICAL, not just close, and show no drift at all. Several types are available as platinum matched sets. The tube factory has already burned in the tubes, also when you order non-PL tubes . The platinum matching (PL) is an additional process, as we describe below. If you have been matching tubes yourself, on a tube tester that can really load the tubes at full dissipation, you will have noticed, matching actually does require a burn-in, and also the matching seems to change after storage. This problem had been recognized by Electro Harmonix, and the tubes are burned in TWICE by the (PL) process.
SIMPLIFIED TEST FLOW of the (PL) process. (Step 1 consists of many sub-tests, not shown here)
Initial tube activation (several steps, some compare to burn-in)
Test tubes, and reject the bad ones
First burn-in (24hrs)
Re-test tubes, and reject the bad ones What follows now, is the PLATINUM process
Long time storage of the good tubes.
Second burn-in (24hrs)
Re-test tube data again . Split tubes in "platinum" and "regular". Platinum are the ones that have not CHANGED specifications. The main criteria is the NEW bias (plate) current measurement, and compare "before" with "after" testing.
Final packing of the tubes in pairs or quads.
This is the ultimate way to guarantee stabile tubes. With JAC-Music, when you order four PLATINUM matched octal tubes, you will get automatically a platinum matched QUAD, at no extra charge! Ask for a Quad at no extra charge with 2A3 or 300B. When available you'll be send this.
Note: You can verify the platinum matched tubes, and you will see that these are the ones that bias immediately stabile after warm-up, and also all tubes from a quad or pair stay exactly at the same operating point!
Always ask for "PL" tubes!
