Replacement tubes for a UA 610?

I'm thinking about trying a few different tubes for my UA Solo 610. I've heard the stock items are OK, but by no means fantastic. Does anyone know enough about tubes to make recommendations? I'm completely out of my depth on this. From memory I think the UA610 runs a 12AX7 for input gain and a 6072 for output.

I'm not wanting to modernise it's sound - I love the 610's thick vintage tone (it's the king of fat!). But if alternative tubes can offer a likeable improvement on a mic-pre I already love, I want to give it a try.

That UA Solo 61 is quite a unit!

The 6072 is actually a 12AY7 selected for low noise ... if that's a phase inverter, might as well leave it in there as it'll have little effect on the tone. The 12AX7 is likely the driver ... I'm an NOS freak and would suggest something like an old RCA (known for their warmth) in that position ... GE if you want to brighten it up a tad, Mullard if it's already bright and you want to subdue the highs. Any change will be subtle, especially once it's in a full mix.

Of course this is just one opinion ... some folks haven't drunk the NOS kool-aid and will tell you it won't make much difference or suggest a new-manufacture tube that's worked well for them. Experimenting with tubes is lots of fun but can be time-consuming. I replaced the tubes in my GT Brick preamp and liked what it did.

Thanks Woodman, some $50 RCAs are on the way :). Seems there's quite a market for NOS tubes - i bid on five separate auctions before i finally won!

I picked up a used SOLO 610 about 5 months ago. I hadn't even thought about replacing the tubes yet until I read this thread. :lol: Thanks for planting the seed.

Try a handful of different brands. Those new peanut tubes don't cost a whole lot. Also try a 5751 it has 60% of the gain of a 12ax7. You don't have to go down the NOS road for those tubes. Only the cork sniffers are into that. Plus nobody is going to dig into your vintage cool rack gear to find out.