Here is more on valve matching. Most valve manufacturers will match output valves in pairs and quads with varying degrees of accuracy. I have written about this previously here. Also you might about to read our thoughts on why do matching in the first place and click here for the article!
Valve manufacturers in general do not provide matching of pre-amp valves like the ECC81, ECC82, ECC83 ( 12AT7, 12AU7, 12AX7).
You might be asking how come I can buy matched pre-amp valves? The answer is simple. Suppliers like ourselves have to buy buckets of the standard valves and test every one to find the matched valves. It can be a long slow process. Of curse time means expense. There are only a few that meet the requirements of a matched pre-amp valve. So this is the reason why matching costs extra.
Valve specifications date back from the late 40’s and 50’s and are quite loose. Most of the performance specifications are ” typical”. So there are no guarantees on what the valve spec is. It is a bit like going to your local car dealer and asking to buy a new 4 door car. In the valve world, the dealer will tell you, ” yes indeed Mr customer our cars typically have 4 doors” So you order one and a 2 door car arrives. The salesman then tells you ” they only typically have 4 doors, but they come with anything from 2 doors to 7 doors, we did not guarantee a 4 door”. This is exactly the situation with valves. Being old technology in reality means the anode current on a output valve can range from 35-65 mA and still meet the “specification”.
I have the respective valve manufacturers pre- match them in pairs and quads. Then I test and check them for current and the “mu”. Quite frequently I have to mix and match them to get the best overall match On pre-amps its down to us to test and search for the good matched one. It is labour intensive and slow as you have to let each valve under test get totally up working temperature in order to get accurate measurements.
The hidden benefit for every customer that does not buy matched valves is that we have tested every valve we sell.
Shopping Basket
