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5963 tube swap in for 12AU7?
Posted:
Fri Oct 09, 2009 5:50 pmby justinsweber
Hey Everyone... I bought a cash of these RCA 5963 tubes.. told that they are very very similar to 12AU7 tubes but draw more current.
With the DIY70 board can it (the driver board) support this tube without changes?
"5963
This tube makes a decent substitute for the 12AU7 as the characteristics are almost the same. The 5963 has a slightly lower plate voltage rating compared to regular 12AU7. The 5963 has a max plate voltage of 250V while 12AU7 has a max of 330V. This tube has a specially designed cathode which can withstand long periods of time in cut-off without hurting the tube. "
Posted:
Fri Oct 09, 2009 8:30 pmby Ty_Bower
Draw more current? They must be talking about something other than heater current, which is what I'd worry about first.
I haven't tried the 5963 myself. I did run a Raytheon 5814 in place of the 12AU7 in my ST35, and I really liked it a lot. I'd give the 5963 a go, and see how you like it.
Posted:
Fri Oct 09, 2009 10:04 pmby justinsweber
anything about setup of this tube that is concerning?
Posted:
Sat Oct 10, 2009 3:06 amby kheper
justinsweber wrote:anything about setup of this tube that is concerning?
I have used RCA 5963 tubes with the diytube driver board. The heater current draw for the 12au7 and the 5963 are identical (.3A). Check the voltages on pins 1 and 6. If they are within 10% of 250V (on the high side), you will have no problems. (The manual gives the voltages for pin 1 and 6 of the 12au7s as 245V.)
These tubes were used in some of the first computer circuits.
They are as audio tubes very neutral sounding. Transparent with a decent mid-range response.
Posted:
Sat Oct 10, 2009 3:19 amby justinsweber
thank for such a solid response.
Posted:
Sat Oct 10, 2009 9:17 amby EWBrown
I've tried out the 5963s in the Bottlehead "Foreplay 2" linestage and they worked very well as a stand-in for 12AU7s. The characteristics are close to the 12AU7s, but not exact (slightly higher mu) but they are definuitely "close enough" for most audio applications, with no circuit changes necessary to accomodate them.
I've also used SRPP 5963s in my PSET 6S4A amp, and they fit the application perfectly! I started out with 12AT7s in the SRPP driver (RK=RA=1K), but they had far too much gain for the 6S4As, so I tried the 5963s and I am very pleased with the results.
HTH
/ed B in NH
Posted:
Sat Oct 10, 2009 1:51 pmby kheper
justinsweber wrote:thank for such a solid response.
No problem.