Thread: Tad
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Old 23rd July 2017, 06:51 PM
Ardee Ardee is offline
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Join Date: Sep 2006
Location: UK
Posts: 25
Default Re: Tad

Greg,

If you run the valves at low current and low bias voltage, any slight difference in the valve's characteristics is likely to be audible. I am running them with reasonably high current and bias voltage, and with low signal levels. I cannot honestly say that I can hear any difference between two valves which have matching curves, even if they are a different brand.

I plot the curves of any small signal valves I use, so those that are poorly matched or obviously not linear don't get listened to. I find that a good TAD sounds the same as a good EH or a good NOS. NOS are more of a gamble, as TAD and EH Gold are selected, whereas NOS E88CC and ECC88 vary wildly. You need a large batch of these to find a couple of good ones, probably because the same batch has been picked over several times in the last 50 years.

The Russian valves tolerate higher cathode heater voltages than NOS, so are less likely to go noisy.

I think TAD aim to serve the guitar market, where AC gain is more significant than DC matching. EH seem more interested in the HiFi market, and I have not found any bad EH Gold valves, other than one which was clearly damaged by a dealer (Hot Rox) who admitted having no idea how to use a valve tester. I would advise buying from a dealer who does not try to test small signal valves which are already factory-matched.
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