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7025 VS 5751 ?


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My 6G6-A came with 7025's in both pre's and the PI.


Swapped in a shed load of tubes from all over, including Mullard ECC83's from the 50's and 60's.....

.....and keep coming back to those 7025 bottles. I know they are just low noise 12AX7. I know

the 12AX7 is just the US name for ECC83, I know the Mullards SHOULD be the holy grail, but

those GEC 7025 tubes are the business.

Never tried 5751 - word is they are mil-spec, built like bomb-shelters, minimal microphony

and a very slightly lower gain-factor, and I keep looking for them but never find them.


I have faffed about with 12AT7's in V1 and in the PI - but the 6G6-A seems to do it's magic

best on the specified 7025 tubes. I guess the Fullerton crew new what they were doing.


Interesting to find them sounding good elsewhere.....

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I can't comment on the differences between a 7025 and a 5751 but, in my experience, one size doesn't fit all and some tubes sound better in some amps than they do in others. I bought a couple of NOS Telefunken 12AX7 preamp tubes a couple of months ago that sound great in my small Fender amps (1966 Champ) and a Blues Junior but they sounded too thick in my Mesa Stiletto which sounds better with a new JJ. My advice is to experiment with your amp(s) and find out which works best for you.

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I don't know s*** about tubes per se, but I gotta little ol' '63 Gretsch Dual Twin that is mighty nice. It's almost as old as me (ahem!), but everything still works perfectly (can't same the same for myself), and sounds great, though it's a bit noisy. I'm gonna get it checked out and cleaned up this summer.


So, Murph, what's the deal with tubes -- do different tubes affect sound differently, add functionality, what? Can tubes of the same size be used interchangeably? Why or why not? I can hear the difference between a tube amp and non-tube amp, but don't know *why* it's different. Is this something that can be explained briefly here, or have you got a book you could recommend?

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Tubes are a HUGE topic and I recommend doing some searches of various guitar related forums and web sites. But, here in this thread we're discussing preamp tubes based on the fact that not all tubes by different manufacturers sound the same; different brands of the same type can sound and perform differently and SOME types of tubes can be swapped in for different types. Always exercise caution when considering using tubes that are not specified for an amplifier.


Here is a pretty good FAQ:



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Thanks, RichCI, I will check out the link.


Though I started out on electric bass and guitar, for the last several years I've been playing acoustic guitar only. That said, I've recently dusted off my old Tele and have been playing it a bit as of late, using the Gretsch amp I mentioned above. When I was younger and played professionally, I didn't care about how things worked, as long as they did work and provided I could get the sound I wanted out of them. I didn't take care of gear much either, I just used it. Now I spend a fair amount of time trying to figure out how things work, what makes them sound they way they do, and try to keep my gear in good shape. Before I take that old Gretsch in to have it serviced, it might be good to read up on tubes a little, see what kind of differences they can make and consider the possibility of tweaking what I've got in there currently, if it seems desirable and won't break the bank. We'll see.

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Without doing the link, he's the basic's.


A 12AX7 is a general usage tube. They were used in radios, televisions, organs, ect., ect. for decades. And Fender, Gibson and Marshall amps.


The 7025 was another version built for "business". A little "tougher", if you will. Same tube, just "tougher"..


The 5751 has a different story.


JAN means.....




and they are built to better specs, back in the day......


While they may sound a little harsher, they are built to kill people......


I LIKE this in a tube.....


Just sayin'.......



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