what is the upgrade?
14 responses Add your response
I had a 21A on loan for an audition and it was the stock unit. I don't remember what the stock output coupling caps were. But definitely remember seeing several Orange drops. I advice replacing those caps as well. They tend to blunt the transients, especially the trailing end. Also, I'm sure you have rolled the tubes?
How good are these tubes?
you have a solid state amp, so a warmer 12AU7 might be preferred
best in order
all are nice, smooth high end 12AU7's
2 low noise pairs) ECC82 Mullard branded Philips NOS 1964-1969 in Philips boxes (recommended)
1 pair $160) 11.8/12.2 and 11.4/11.6ma 1967 and 1969
1 pair $160) 11/11.8 and 11/11.2ma 1964 and 1966
1 platinum low noise pair $150) CV4003=12AU7WA Brimar NOS in original boxes 1974-1975 1-5% matching, boxes moisture damaged
1 tube) 12.2/12.5ma 1974
1 tube) 12.5/12.7ma 1975
Low Noise Platinum Pairs $125/pair) CV4003=M8136=12AU7 Mullard "Box Plates" NOS copper grid posts 1982-1985 most in original boxes
a 5814A could be used as a sub
1 platinum low noise pair $150) JRC-5814A RCA black plates double mica 1962-1965 original boxes (best pair)<-------
1 tube) 12/12.1ma
1 tube) 12.2/12.4ma
No one can answer your question as tubes are opinion orientated and specific to ones gear/taste.
There is no reason at all to spend more than $60.00 for a pair of 12AU7/5814A tubes for your particular unit. It would be a waste of money.
The GE BP 5814A is dead neutral in sound. That means wide bandwith. No rolled of highs, no rolled of bass, no excessive brightness, very dynamic etc.
E-mail me, I've got lots of tubes. I'm not out to make any $$$. I do not need the money, but also am not a library. Be specific as to what type of sound you like.