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.
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.
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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:
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. |
@mulveling Fascinating story on your 5751 Trial. @bkeske I have listened to both of you since I found a Seller of some Telefunken 12AX7’s with a Great Track Record on USAudioMart and Ebay. Fully Tested and Guaranteed to function to my satisfaction in the Trumpet MC. Cheaper than the main Tube Sellers also. They will be the Rebranded Tele’s as bkeske has suggested. Thanks for the assistance on this. |
So I had a channel imbalance yesterday. The investigator in me found one of the “new” mallards was the culprit. I’ll keep playing. @djohn please update us when you get them in and settled. (Seems this might turn into the Hagerman trumpet tube thread).
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Not a problem. I think you will like what the Tele’s offer. More detail, more air, and increased smoothness. Not ‘gritty’ in the least like some of the newer tubes. I was running 4 smooth plates, but then tried a couple CBS Hytron black plate 12au7’s, and they offered even more detail and transparency. They replaced some old 12au7 Brimar’s. But, it soon became clear the 4 Tele’s and 2 CBS Hytron’s were too much of a good thing, but I like the Hytron’s a lot so did not want to put the Brimar’s back in. Thus, decided to combine 2 old Mullard Blackburn 12ax7’s with 2 Tele’s, and that was the ticket. The Mullard’s brought back some warmth and weight without giving up detail, in the mid’s and lower mids especially. Just balanced everything out. Have fun. I find the Trumpet is very good at allowing a tubes ‘signature’ to shine through. Then it’s a matter of finding a combo that sounds good to your ears. |
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