12AU7 for DeHavilland 50A Amplifier

To all those "in the know"...  I have a pair of DeHavilland 50A mono blocks which use a 12au7 input tube.  The amps are a bit "soft" sounding in my system, lacking some of the leading edge transients which I had grown accustom to with my prior solid state amplifier.   I was curious as to whether replacing the current Amperex NOS 12au7's with the Gold Lion reissue 12au7's (the amps were designed around, and use, the Gold Lion KT88 power tubes) would give a bit  more of a well defined transient type of presentation, or would I be giving up too much sonic beauty that the Amperex tubes provide?  FWIW, I tried (with Kara's OK) substituting the KT88's with KT150's, and wound up returning to the KT88's as the KT150's proved to be a little too lean.
Thanks for all your input on this...


I'm not in the know, but trying the Gold Lion12au7 might help.  They are not so expensive that they are a major investment.  

Another option is talking to one of the highly regarded tube sellers,  the names of whom you can find in the thread, "Where do you guys buy tubes?", just below this one.  One of these guys may be familiar with your amps and the effect a particular tube might have on the sound. 

It may be that your DeHavilland amps just have a softer sound.  Either way, good luck and let us know what you end up with.


Thanks, Tom.  I realize they are not a significant investment but thought I would float the idea to see if I was headed in the right direction.  BTW, I have it on good authority that you are indeed in the know (I read this somewhere on the internet, so, of course, it must be true...).
They must have been referring to tomcy1 or 2.
Try Seimens 12au7 - very dynamic and superb bass.  I prefer them over a variety of Mullards, RCA Cleartop, and Radiotechnique tubes that I've tried.
I have tried just about every 12AU7 variation out there, and the best match to bring about the qualities of dynamics, transient attack, detail and energy would be the Amperex 7316. More lively than the Amperex 12au7 you are using now, with even better detail and soundstage too. Steer clear of the Mullards if you do not want a warmer sound than your current Amperex. The RCA cleartops are very lively and energetic on the top end, but are very lacking in lower midrange and bass weight.
I second bigshutterbug, i using 7316 now. others heard my system thought i had added a subwoofer. Transient is great with energy too. 
Tom, don't let those numerically challenged wannabes steal your thunder...
Bigshutterbug and Philipwu - the 7316 is a drop in replacement for the 12au7? Philipwu, are you using an Amperex 7316 as well?
yes, and Amperex 7316 is the same as 12au7\Ecc82. Very well balanced tube in audio spectrum.
The Amperex are "soft" in this regard. The 7316 is better, but if you want dynamics, the CBS 7318 is your tube... Good luck finding any though!
Yes, the 7316 is a direct replacement for the 12au7. A very strong, well matched pair is not cheap, but should last you a long, long time. Fortunately, I seeked them out for my collection over 20 years ago, before the prices got crazy!


A lot of good tube suggestions in the above posts. I would also suggest changing the amp fuse to a Synergistic Research SR-20.

What wall outlet  are your amps plugged into? This can also make a significant change in sound. A Furutech GTX-R has a big open soundstage with a well defined leading edge to notes.

David Pritchard