What are you looking for? If a valve meets the spectrum of specs acceptable for a PCC88 it is a PCC88.
I am going to use them in a moving coil Riaa amp.
What I was looking for was if any sound diffrence between the 2.
What I was looking for was if any sound diffrence between the 2.
I bought a box of 100 12AT7WA, and there is an incredible range in just those tubes. If you have stringent requirements for noise and matching, then you may need to be prepared to buy a few and test them.
I'm not familiar with the "P"'s, but I have a nice little stash of the "E"'s as in ECC88/6DJ8, and they all measure and sound different. The very worst I have are some RCA branded, made in Japan 6DJ8, and my preferred are, surprisingly, the Zaerix made in USSR I bought half a century ago as spares for the scope I had then. If I had to choose only between Siemens and Sylvania, I'd take Siemens anytime.
A word of caution: if you were to run them as the 1st stage of an MC preamp, be prepared to buy a bunch of them to select for noise: they can be very microphonic in that position. I use the Zaerix for that: they're border line noise-wise, but their sound is glorious.
A word of caution: if you were to run them as the 1st stage of an MC preamp, be prepared to buy a bunch of them to select for noise: they can be very microphonic in that position. I use the Zaerix for that: they're border line noise-wise, but their sound is glorious.
If you are a really good designer, then use a 416A Planar Triode in True Grounded Grid mode as your input tube.
Caution:
Without proper engineering, you will burn out the fine Moving Coil wires of your cartridge.
A step up transformer is another method to use for a moving coil cartridge input "stage".
Solid State Discreet; and Op Amps are a couple of other methods to use as the input stage for a moving coil preamp.
For any of the above, Your Mileage May Vary.
Caution:
Without proper engineering, you will burn out the fine Moving Coil wires of your cartridge.
A step up transformer is another method to use for a moving coil cartridge input "stage".
Solid State Discreet; and Op Amps are a couple of other methods to use as the input stage for a moving coil preamp.
For any of the above, Your Mileage May Vary.
If I may disagree: a 6DJ8 in common grid has an input impedance of about 100 Ohms or so, which could be a bit low for some cartridges. Plus an input cap is pretty much mandatory, and a pretty big one too.
I'm currently trying out a JFet/tube cascode which looks promising, at least on screen. You can think of of it as a common source JFet current driving a common grid tube, with any input impedance you fancy and no input cap required.
I'm currently trying out a JFet/tube cascode which looks promising, at least on screen. You can think of of it as a common source JFet current driving a common grid tube, with any input impedance you fancy and no input cap required.
Zung,
Just as I said . . . a really good designer.
Agreed, the input impedance of a grounded grid 416B can be quite low,
but it is higher than 1/Gm, it can be raised by the factor of RL/(u+1); so it is plate load dependent.
And, yes, a very large input cap is needed (electrolytic caps need not apply for this application).
That capacitor presents the other problem . . . the transient current to the moving coil . . .
1. Every time the preamp is powered on
And
2. Every time the preamp is powered off (including a Power Mains Outage).
. . . Again, a really good designer is required.
I did find the 416A, it has glass spacers. I am not sure about the 416B spacers. The u is so high, that RL/(u+1) can make for a good input impedance.
And do not mis-understand me, the JFET, JFET/Tube Cascode, Op Amp, and MC transformer are all valid solutions, and certainly less dangerous to the moving coil.
Each have their tradeoffs.
"For every engineering problem, there are 100 solutions, of which 3 will actually work, but only if they are implemented properly" - Me
Remember the Tacoma Narrows Bridge.
Just as I said . . . a really good designer.
Agreed, the input impedance of a grounded grid 416B can be quite low,
but it is higher than 1/Gm, it can be raised by the factor of RL/(u+1); so it is plate load dependent.
And, yes, a very large input cap is needed (electrolytic caps need not apply for this application).
That capacitor presents the other problem . . . the transient current to the moving coil . . .
1. Every time the preamp is powered on
And
2. Every time the preamp is powered off (including a Power Mains Outage).
. . . Again, a really good designer is required.
I did find the 416A, it has glass spacers. I am not sure about the 416B spacers. The u is so high, that RL/(u+1) can make for a good input impedance.
And do not mis-understand me, the JFET, JFET/Tube Cascode, Op Amp, and MC transformer are all valid solutions, and certainly less dangerous to the moving coil.
Each have their tradeoffs.
"For every engineering problem, there are 100 solutions, of which 3 will actually work, but only if they are implemented properly" - Me
Remember the Tacoma Narrows Bridge.
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