Hybrid Tube Preamp - Loud Pops and Crackles
My stalwart VTL 7.5 iii pre is broadcasting loud pops and crackles through my speakers, scaring me about damage to the speakers. First, I thought my aged 12au7 NOS 7316's tubes were dying, so I replaced them with NOS Amperex Bugle Boys. The pre started with the loud pops and crackles again.
Are both of these tubes dying, or is the problem with the pre itself? Any thoughts? Thank you. Neal
Personally I would order a pair of JJ 12au7 from somewhere like Tube Depot. Pay a few dollars for matched tubes plus screened for noise and you will either solve the problem or at least be sure it’s not the tubes. Could be loose tube sockets. You can gently re-tension them and sometimes that solves the problem. Good luck |
I'm a bit confused by the suggestions that you mess with the tube sockets -- the process of removing the original tubes and putting in new ones should have taken care of any issue that was caused by corrosion build-up or a poorly seated tube. Next, the odds of a different set of tubes exhibiting identical problematic behavior is unlikely (though not impossible.) If the volume control, you'd almost certainly notice the problem as you turn it up or down. Once you've toyed with everything and re-set the tubes and all other cable connections (not forgetting to plug/unplug at the amp end) the last thing I'd suggest is to disconnect the preamp from the amp. If the amp by itself continues to make noise, it's not the preamp causing the problem. If the amp is quiet, plug in the preamp, but with no sources connected. If at this point the noise returns, it's time to take your preamp over to the shop for a professional look. |
One colleague (oddiofyl) above suggested re-tensioning tube sockets.
I will follow your suggestions and see what happens. I too am surprised two sets of tubes causing the same noises, so it is unlikey the tubes are the problem. Thank you. Neal |
