Thoughts of a Preamp Upgrade - Looking for Input

[RPMac]

The problem with the 12AX7 is that as a voltage amplifier, it has a ridiculous amount of gain. Nobody needs 30+dB of gain in their tube linestage, and having that results in people complaining about how they can only turn up the volume knob on their preamp 5 degrees before it's ear bleedingly loud. As a cathode follower, the 12AX7 can only run a scant amount of current, so if you load it down it will really struggle to operate well. This is why the Triode Corp. preamp uses a 12AX7 in parallel for their cathode follower, but quite literally any of the other common dual triodes is a better choice for cathode follower duty. If you find a preamp with 12AX7s and low gain, it may just be that it's a copy of a vintage design using global feedback, and these are not the greatest sounding circuits either.

I personally prefer a directly heated triode gain stage with an indirectly heated cathode follower buffer. I've had good results from single gain stage tube preamps, both with and without output transformers as well. I think the recommendation of the Aikido circuit is a good one, as that is well developed and well documented, but I would stick with the lower mu higher gm dual triodes in that circuit.

+1 for the direct heated triodes
I don’t think I have +30dB in my entire system…and, with the right speakers, haven’t needed it.

 

[Tlarwa]

@Wntrmute2, I just read through some of that build thread. While I’m sure it would be a satisfying project, I’m not sure I’m up for that level of challenge, given that my electronics builds to date have been kits.

 

[Wntrmute2]

Got to start somewhere - I did. Built two kits before diving in. Check out the simple schematic Paul designed. I added a lot of complexity with dual VR tubes and the 2C22 tubes.

 

[JohnVF]

Or you could get a transformer volume control.

 

[JohnVF]

A local member here has a Supratek preamp and I have to say, its really nice. And their prices aren't crazy for what you get. Plus... they're beautiful. I personally went with a solid state option but were I looking for a tube based pre, they'd certainly be up there. It's the preamp that got me thinking about replacing my TVC, as it was doing something the TVC was missing.

Portfolio | Supratek

www.supratek.com.au

 

[paul_b]

Or you could get a transformer volume control.

A TVC after a 300B would be a very good approach.

 

[jblnut]

Well if we're going down the DHT road I am still saving my pocket change for one of these someday. Heard it at the NYC audio show on 2019 and talked to Vinnie himself at length. Not a budget piece though and those that have them are not parting with them.

Review: Vinnie Rossi L2 Signature Preamplifer and L2 Signature Monoblock Amplifiers (Part 1) - Twittering Machines

Michael Lavorgna's Twittering Machines: HiFi with a twist

twitteringmachines.com