They aren't very linear because of their variable mu and hence aren't recommended. They might be interesting in a guitar effects box, but otherwise I would stay away.
I have used PCC189 in a RIAA second stage (JFET shunt cascode 1st stage).
They are not very linear (as Kevin has said) for large signals -
BUT, if you run them in cascode (shunt cascode for preference) and 90V/15mA, they sound very fine for low-level signals. Low cost way to make a preamp full of Mullard valves, anyway!
They are not very linear (as Kevin has said) for large signals -
BUT, if you run them in cascode (shunt cascode for preference) and 90V/15mA, they sound very fine for low-level signals. Low cost way to make a preamp full of Mullard valves, anyway!
Phono Preamp?
Did the batch of tubes include any 6V6's? (just joking).
Like you, I'm puzzled.
Why not? could use a photocell to adjust the RIAA correction depending of the amount of light you have in the room?
You could use 189s for every stage in the phono preamp, and explain to people that they add musicality and compensate for signal compression in the cartridge. Soon, everyone will want one!
To be serious, yes, you could use one for the first stage. They are a lot cheaper than 88s, and a small unbypassed cathode resistor (27R?) can help linearise them.
To be serious, yes, you could use one for the first stage. They are a lot cheaper than 88s, and a small unbypassed cathode resistor (27R?) can help linearise them.
I have used them and I did not choose them at random. This is my story.
Several years ago I came across a article on the WWW. The question was posed “Is the 6dJ8 suitable for audio? Turns out someone had mislabeled Tunsgram variable mu valves as 6DJ8’s. The article was rather long winded. The short version is if the tube was biased toward the high end of the anode current scale it behaved as you would expect for a 6DJ8. At the 2, 3 & 4 ma anode currents it was very nonlinear.
The PCC189 is the 7 volt version of the imposter valve. I found a couple of dozen Tunsgram PCC189’s for near $1 each. A pair of them went into a common cathode line amplifier that made an Alesis RA 150 sound very Class A SET like. Another pair was biased up hot, I could not tell them from 6DJ8’s in that application. The fun was worth the few dollars.
DT
All just for fun!
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