I had a similar experience, i had read the supposed merits of the russian reissue tungsol 12ax7 so i bought a pair and they didn't even last four hours so i popped my trusty 1955 GE 3mica blackplates back in and felt better immediately, i find the military specific tubes superior in my 24/96 alpha, the mullard 12at7wa [wa is english designation for military as i believe wb is for russian military] pair that i have have at least 1000 hours on them with no trouble, 500-600 hrs on the 5751's - no trouble. If you do need svc. on a CAL product don't hesitate to call Approved Audio in Conneticut, fast turn around, reasonably priced, very knowledgeable about the product and has parts stock, he just repaired an Icon cdp i use in my system at the shop and it works like new.
I think my CAL Alpha DAC is broken...
I've owned the 24/96 version for at least a dozen years. Lately, it has become very temperamental about what tubes it will accept. The left channel blows out anything other than a Sovtek 12AX7WB! I've had the following new-out-of-the-box tubes fail within the past year: Sovtek 12AX7LPS (3 of them!), TungSol ECC803 and Sovtek 12AX7LP. Typically, they last only a few hours.
I'm eventually going to take it for repair, but I'd appreciate any thoughts on:
a. why it might be doing this now?
b. why the Sovtek WB seems more robust?
Thanks.
I'm eventually going to take it for repair, but I'd appreciate any thoughts on:
a. why it might be doing this now?
b. why the Sovtek WB seems more robust?
Thanks.