VAC Preamp: Is my Phono stage failing?

Tpreaves, I would, but I neglected to have spares on hand.

Ghasley, Thanks Geoff – I'll PM you.

Maineiac, Yeah, I've been scratching my head about whether this could be a ground issue because it came out of nowhere. Just started happening a few days ago.

Wearing my Sherlock Holmes hat, I disconnected the tone arm while the hum was happening, but in stages: First I disconnected the right channel... hum was reduced. Yanked out the left RCA, hum reduced even more. Removed the ground wire... even more reduction. However, even with no tonearm connected the hum was still loud and unacceptable when selector was set to Phono. Then I tried every other source selection on the knob... dead quiet. Using one of the quiet settings, I switched the other selector from "Source" to "Cinema Bypass," which is connected via IC to my Marantz HT receiver, and the hum comes on strong as ever! So I disconnected my VAC from the Marantz and yes, the hum is still there!

Any tech wizards out there have a diagnosis?

Just rolled a pair of NOS Telefunken 12AX7 to replace the stock VACs. And for about 40 minutes of horrible sounding crap coming out of my speakers (how long does it take to break in new tubes?) the hum started again – it took longer, but it did show up.

So it's probably not the tubes after all. If my phono stage is indeed needing repair, which means packing up and shipping my pre to Kevin way across the country, which would be another expense on top of the repair costs... I may consider an upgrade to an outboard phono stage instead of fixing the internal phono stage.

Does anyone know what outboard phono stage would be equivalent to the VAC's built in (which is awesome BTW)? And once I get a bench mark, what would you recommend as a significant upgrade from there?

If the VAC phono fits your needs and you love it, then the repair costs will likely be a fraction of what it would take to get a closely performing outboard unit . I bet you the cost of repair would not even be what you would want to spend on a good power cord for an outboard phono stage. Call Kevin or Brent and they will tell you if there is something obvious to check or do and the range of how much you are looking at in terms of repair.

The advantage of an outboard phono is that most have a great deal of flexibility in terms of gain and other settings that allow you to use many different cartridges. VAC might box you in a little with the phono but I am guessing it is extremely good for the carts that can be used with it.

Have you asked Kevin what he thinks the problem might be?

SOLVED! Well, almost.

Maineiac, Thanks, I really wonder how much I would need to spend on an outboard tube Phono Preamp to be significantly better than the VAC's.... sounds like it might be a lot. I would love to audition the Fosgate Signature, it's received good reviews and it looks so cool.

Pubul57, I spoke with Brent at VAC and he never heard of this problem and said to send it in for a check up. I guess the very notion of being without music for a few weeks was bad enough to kick my brain into gear and identify the problem's source.

My system is on two 20amp dedicated lines and all components are fed power from a AC regenerator that completely isolates the system from the wall power. I also have a hot tub in the back yard on its own separate 20a circuit.

Every time the hot tub motor turns on, the hum shows up in my phono stage. If I then turn off the tub, the hum disappears.

Considering the system and the tub are on completely separate dedicated circuits AND my gear is completely (supposedly) isolated from the wall power... how could this be?

I'm calling the electrician back in and I'm going to call PurePower and have a little talk with them. I don't think this has anything to do with my VAC.