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Hagerman Trumpet MC (12AX7 Tube Suggestions)

I have recently acquired a Hagerman Trunpet MC and I am extremely pleased with it.

Desire to assemble some 12AX7 sets of (Almost) NOS Tubes to Tube Roll. 12AU7 positions are purchased but the 12AX7 Tubes are a minefield and somewhat costly after my research.

First question; Have any Owners here used the 5751 Tube in the 12AX7 positions?

Second question; Have any Owners here had any sonic success with 12AX7 USA Brands such as Sylvania as an example. I am reading mixed longevity views on the RCA Blackplates and not many good comments on the GE types.

I am very gunshy on the Re-Issue 12AX7 Tubes also.

I primarily listen to Classic Rock, Progressive Rock, Folk, and some Classical.

Suggestions would be much appreciated.

 

djohn
mulveling's avatar
mulveling
1,774 posts
 

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 :)

djohn OP
64 posts
 

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.
 

simao's avatar
simao
1,750 posts
 

Picked up my second Trumpet over the years a few months ago. Brent Jessee over at Brent Jessee Tubes recommended NOS Amperex BB's. I can't quite remember what tubes I rolled in my previous Trumpet iteration, but it sounded wonderful no matter what. Great thread, btw!

lewm
12,556 posts
 

The quote from Mr Hagerman about the 5751 may indicate that the 12AX7 it would replace is involved in the RIAA correction filter, as well as adding gain. Since the 5751 might change slightly the output impedance of the stage, it might also affect RIAA, resulting in a sonic coloration that has nothing to do with the brand or vintage of the 5751 chosen.

mulveling's avatar
mulveling
1,774 posts
 

Well I actually tried a pair of 5751 in the 1st 12AX7 slots. It sounds great - this is an improvement over the Russian Tung-Sol gold pin 12AX7 I had in there, for sure. Sweeter midrange, a little more 3D - as is often the case going from Russian to good vintage tubes. Excellent clarity. It did NOT shift the tonal balance to darker. It’s just nicer, overall. It did lose a dB or 2 - that’s noticeable and easy to adjust for.

These are just RCA TM BP 5751, since I have very limited tubes available here where my "B" system is located. Also the "B" system is something I just recently put together, haha. So at some point I’ll bring over a bag of vintage 12AX7, 5751, and 12AU7 and go to town as I continue to familiarize myself with the B system and refine it (basically it needs a better turntable). We'll see if 5751 hangs with the better vintage 12AX7. 

But 5751 in that first slot is good! No worries if you want to try it there. I guess I should also try the 2nd slot next.

The B system:

  • Tannoy Glenair 10 speakers
  • VAC Signature 200 iQ stereo tube amp
  • Rogue Athena tube preamp
  • Hagerman Trumpet MC
  • Fluance RT85 w/ Ortofon 2M Blue - this will be replaced with Clearaudio Innovation Compact in a week - but it’s kinda neat how good it sounds through a downstream which far outclasses it.

Sure I get the concerns about 5751 subs affecting the RIAA EQ. That’s why I’ve shied away from using 5751 in phono stages in the past. But sometimes you just have to try things. There can be a lot of variance in measurements between 12AX7 tubes, too.

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