Cascais.....Ditch the Sovtek 6550 FYI,
http://www.audioaficionado.org/audio-research/35305-differences-between-ref-250-ref-250se-9.html
Cascais.....Ditch the Sovtek 6550
Excellent call on the GE 6550s!
Can you still buy NOS GE 6550's??
My amp came stock with those tubes and they are as you say...excellent. Since I was unable to source them, I went with Winged C 6550's which are also great.. And are now also very difficult to source.![]()
The NOS GE was a great tube - those I have measured had significantly lower leakage grid current than other brands or KT's compatible types. When the tube is used at low current, as in the ARC series regulators, this results in lower noise in the regulated voltage. However they are now very difficult to source. When I owned the VTL750's that used tens of 6550's I selected the best ones for the ARC power supplies.
I found them at RF Parts in San Marcos, CA for a lot less than Tube Depot or one or two other places that had them. I ended up buying 8 of them. 2 each for my preamp and phono pre and spares for each. I should be set for a while.
Interesting - what is the difference you see on orchestral between these two tubes, Roger?
Sensible approach, Should you have not tried any other valves than ARC factory I would urge you to acquire a tested NOS General Electric 6550A in your Ref5SE, your current pre has much more to give without the stock Sovtek 6550 which is glassy and 2 D in comparison!
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