Hagerman Trumpet MC (12AX7 Tube Suggestions)

Tube rolling is a subjective sport.

You guys all do realize that a 5751 affords less gain than a 12AX7.

@mulveling I also reviewed your previous Posts on the Trumpet extensively before purchase. I was especially struck that you compared it with the Herron VTPH-2A which I also own so I wish to Thank You also.

You made me look at the modern Tung-Sols and this warning was on the Viva Tubes Site; " These tubes are great for linestage preamps, but generally not phono stages where a very low noise floor is required ".

It looks like with your comments and bkeske's comments that I have to search and pony up for the Telefunkens.

@djohn

Awesome! So glad you’re enjoying it :)

Just this past week I’ve been playing the Trumpet MC with Plantinum grade gold pin Tung-Sol (Russia) 12AX7 from Upscale Audio - no noise problems there. Maybe Viva just doesn’t like selecting them for this role ;)

But certainly, a good set of Teles will be amazing. I need to dig them up again from my stash. I ’ve been playing with lot of gear the past few years; now trying to settle things down a bit - the ARC Ref 3SE is sold to a friend, the VAC Renaissance SE reigns again in the now all-VAC main rig with Tannoy Canterbury GR, and the new fun 2nd system at my girlfriend’s home is anchored by a really nice set of Tannoy Glenair 10 and this Trumpet MC.

I just went through my photos and see that a couple years ago, when I was really enjoying the Trumpet MC in the main rig (it holds up extremely well and is still probably the best I’ve heard my Benz LPS), I had it stocked with a quad of Tele ribbed plates. So it can use the extra detail and dynamics of this variant (versus smooth plates) without getting too bright - but I also had those warm Mullard CV4003 (12AU7) to balance them out a bit. Shame that Upscale finally ran out of those :(

As @lewm points out, 5751 has a lower mu than 12AX7 - 70 versus 100. But most tube circuits are quite flexible for this. By math 20 * log (0.7) - this is a 3dB difference. However, this assumes an infinite load and in practice it is usually less than this (~ 2dB?). Subjectively, 5751 have a different "kind" of sound. I find them to have tighter, sharper, smaller imaging. They sound very clean and precise. Whereas 12AX7 have a bigger, bolder, more dynamic sound - but with a potentially more "grungy" cast to the sound. But again, haven’t tried 5751 here yet. The GE TM BP are a good go-to for a classic 5751 sound. The "holy grail" 5751 are supposedly Raytheon windmill getters or Sylvania triple mica black plates (TM BP) and I haven’t been lucky enough to snag either. The later 1960’s Sylvania gray plates are awfully bright and lean. Sadly that has been my experience with later make Sylvanias across types - you really want to stick to the 1950s and earlier.

One more note on the 5751 tubes tangent - the absolute sweetest sounding of the GE 5751 TM BP are a specific variant only produced between 1953 and 1954. This variant has unusual silver colored metal "clips" crimped over the plate "ears" that normally poke through the top & bottom mica spacers. These "ears" are normally left bare (not just 5751 - all tube types). For some reason GE saw fit to clamp them down extra tight in this case. And for whatever reasons, this version sounds sweetest :)

From Jim Hagerman the Designer;

Yes you can use a 5751, but the tonality (EQ) will change.  Probably a bit darker.

I will be sticking with the 12AX7.