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What tubes for sibilant SET Triode amp

I have recently bought a Cayin/Spark 9021DEX amplifier. This is a zero feedback SET design in which I currently use the original Chinese made 211 output tube a 6SN7 GTB by Sylvania as a driver tube and a late Siemens ECC88 at the input. The bias on the output tube checks fine the sound is great with a minimal tendency to sibilance. As I am going to buy a set of back-up tubes anyway - which tubes to buy to get rid of the tendency to sibilance? Opinions seem to vary considerably! Any suggestions??

Preamp is a MacIntosh C220, Speakers are Gallo Ref 3.1 and Analog Front End is a VPI Superscout with a Shelter 90X.
hanshhh

Showing 1 response by tfkaudio

tfkaudio
591 posts
 
How sure are you that the tubes are to blame? I wouldn't advise buying some expensive NOS tubes to cure this problem until you know you've isolated it. Buy a couple of cheap JJ Tesla 6922's and try those first.

A couple of other suggestions (I know they sound stupid, but I've done all these things myself)...

Make sure your speaker wire is connected to the TOP binding posts on the Gallo's.

Make sure the top and bottom binding posts haven't been accidentally or intentionally bridged together.

Make sure you didn't reverse phase when you hooked up the amp. Is your new amp phase inverting? Find out?

Has your amp had time to break in?

Is your tweeter set at -2db? Set it to 0 while you get to know your new amp.

Cheers.
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