Tubes 12AU7 vs. 5814A

I just checked my Mac C20 tubes with my new Heathkit tube tester.

I realized I am running GE 5814A in the 2 x 12AU7 sockets.

All the rest are Dynaco Telefunken 12AX7 and 1 mullard 6x4.

Please advise if I should get some 12AU7 tubes or if the 5814 is the preferred substitute for this amp.

Thanks,

Clay

 

Thank you Steve.
Would you suggest getting Telefunken 12AU7 to improve the sound over the GE 5814?
Thanks, Clay

 

Hi Clay, steve has said before that the Tele 12AU7's are not that good. Bugleboys,Mullards, and RCAs are the main choices for good 12AU7's.I've been comparing Mullards and Bugleboys in my 240 amp. Changes the sound a bit, the Bugleboys have more high end response, Mullards have more midrange.

BTW, did you just get your tube tester?

 

Hi Ron,
I did find a Heathkit tube tester TC3 for $40. It is easy for a non techie guy to operate. It is great to be able to test the tubes myself. One good looking Mullard EL34 tested 0.

I put togheter a quad of mullards for my ST70. sounds much better than the solveck (sp?) and even the Siemens.

I have some old RCA black plate 5814. I will try them on your suggestion in the Mac.

All the Dynaco Tele's 12ax7 tested over 93%.

 

Great information.

Thank you very much.

I will looking forward to hearing the Mullards and Amperex 12AU7s in the C20.

I still need a few more Grover cables and some DIY speaker cables to get the most out of my electronics.

 

Hi Clay,

I use 12AU7's in my preamp and I've done some tube rolling. I liked the Amperex Bugle Boys a lot , but the the best tube I found by far was the Amperex 7316 PQ. Just great from top to bottom. Can't say for sure they'll be the best for you, but most people I know who've tried them have stayed with them. They can be a bit hard to find and can also get pricey, but if you're patient you can occaisionaly find a pair for a reasonable price on ebay (or maybe a local tube dealer).

Cheers,
Mike

 

I use 6198 JANs for 12AU7's. Usually RCA's. Just my preference

 

Testing a Amperex 5814A tube in the center slot (preamp) on a Rogue Cronus Magnum II. So far so good, nice detail but not bright.

 

IMO 5814s are the real sleepers in the 12AU7 domain. I have really liked the sound of the 5814s which I have tried.

 

I’ve had an RCA 5814a triple mica tube in my Cronus as well. It ‘s my favorite of the tubes that I’ve tried so far in the center slot.

 

I have tried the following 12AU7's in my Jadis mono blocks...RCA Clear tops, Mullards, GE's and Tele's...to my ears the Tele's are the most musical. The RCA's are good but not quite as musical as the Tele's... in my amps.

 

Although the 5814 replaces the 12AU7 it is a redesigned 12AU7 by RCA to reduce distortion. First 12AU7s were shipped to Collins Radio and Collins reported the tube had too high distortion. It is a fact 12AU7 do have unusually high distortion. But, used as a phase inverter in many amplifiers the high distortion does not show up much vs being used as an amplifier tube. It is not that bad as seen on the plate curves below (top pix), but not near as linear as a stellar 6P5 tube (middle pix). If I had an amp with 12AU7, I would sub a 6CG7 tube. (plate curve lower pix).

 

I had RCA 5814s and they were bright and edgy. Went back to the RCA 5963 black plate, smooth and refined in that particular application, amp phase drivers.

 

+1 5963

 

5963 appears to be a good 12AU7 swap. I suggested a 6CG7, but it needs the filament wires changed. 5963 is drop-in replacement.

 

5963 is a very good tube. Your RCA 5814A was not a good fit for your component/system. I've had good luck with that tube over the years.

 

5814a black plates from sylvania are really great, and cheaper than most 12au7s...

 

I'm quite fond of the GE 5814s. But I doubt that these are still the bargain that they used to be.

 

any old 5814 are really good, like Sylvania Gold Brand 5814, GE 5 stars etc...