[ Winged C EL34's - I ordered an octet yesterday and they are already on their way to me from the USA via FedEx.
... and just arrived, apparently in good order, as 2 matched quartets (4 x 40 and 4 x 39 mA).
Not bad, 5 days from placing the order to final delivery! Thank you Tube Depot and FedEx!
bring them with you i will test them and show you that matched tubes are just a marketing bullsh!!t,The mingda is manual biasing so no need for matched tubes food for thought.
Interesting Mario, they will always make a case for charging more for a matched quad etc so if this is a ploy discovered by actual testing then the various sellors need to be called to book.
Let us all know the actual readings from the tests please.
V
Vita, some clarifications are in order.
Tubes are burned in for 2 main reasons:
a) To stabilize them. Parameters drift over time but the biggest change is initially when first 'fired up' and then they slow down.
b) Weed out the 'infant mortality' rate'. IOW, if they are going to fail it is usually early in the life span.
They are matched for 2 parameters, a) current at a certain grid voltage (bias) and b) transconductance
I think burned in / matched tubes do sound better and it's a good idea from a reliability POV.
I've got boxes of (un burned in) tubes that failed just after new. Very frustrating.