Favorite 12AU7's
- Thread starter LPD
- Start date
True Dat!!!
LPD
Super Member
Me too!!!
ldatlof
We are all steak
I fourth the Amperex but mine weren't bugle boys. Right now I have a pair of Teles in my Foreplay III with no complaints. Here is a mini review of 12AUs7 that I have tried:
• Mullard 12AU7 (Blackburn factory): very nice mid range but rolled off on the high frequencies.
• RCA 12AU7 (Cleartop): very nice top to bottom but with a very extended high frequency that borders on being too bright.
• Amperex 12AU7 (Heerlen factory): excellent tube top to bottom. This one does it all.
• RCA 12AU7 (Black Plate): very good tube but has too much bass for the FP3.
• Sylvania JHS 6189: very good tube top to bottom – rivals the Amperex.
• GE 5814A (5 Star): Similar to the Sylvania 6189. Very good from top to bottom. Almost as good as the Amperex.
• Raytheon 12AU7A (Black Plate): So far it has a very open sound. Bass and Treble are good. Needs more listening.
• Sylvania 12AU7A (Baldwin Branded): very good top to bottom. May be missing the extreme high end. A lot less rolled off than the Mullards.
• RCA 5963: very smooth tube with no weaknesses. Very good top to bottom.
• Mullard 12AU7 (Blackburn factory): very nice mid range but rolled off on the high frequencies.
• RCA 12AU7 (Cleartop): very nice top to bottom but with a very extended high frequency that borders on being too bright.
• Amperex 12AU7 (Heerlen factory): excellent tube top to bottom. This one does it all.
• RCA 12AU7 (Black Plate): very good tube but has too much bass for the FP3.
• Sylvania JHS 6189: very good tube top to bottom – rivals the Amperex.
• GE 5814A (5 Star): Similar to the Sylvania 6189. Very good from top to bottom. Almost as good as the Amperex.
• Raytheon 12AU7A (Black Plate): So far it has a very open sound. Bass and Treble are good. Needs more listening.
• Sylvania 12AU7A (Baldwin Branded): very good top to bottom. May be missing the extreme high end. A lot less rolled off than the Mullards.
• RCA 5963: very smooth tube with no weaknesses. Very good top to bottom.
LPD
Super Member
Thanks for the list. Looks like I've got some rollin' to try. So far the angled ring getter seems the best in my collection but I've only compared it to the Siemens tubes that came with the amp (I suspect they may be RFT's) and a pair of GE's which seemed a little bright on the top.
LPD
Super Member
If your into trying different tubes in a 12au7 socket (that is if you have the extra heater current)
I find most often a 12BH7 or the new JJ ECC99 out perform pretty much any 12au7 in most circuits.
Not sure if this preamp has the current. The specs for the power transformer are on the bottom of it, so I will post a pic tomorrow and perhaps you could help me decipher whether or not there is enough current.
Its only driving two 12AU7's.
LPD
Super Member
Its the diy one I picked up last week. It states 120ma for primary and 2amps for the secondary. Uses two 12AU7's and has a ss power supply.
If your into trying different tubes in a 12au7 socket (that is if you have the extra heater current)
I find most often a 12BH7 or the new JJ ECC99 out perform pretty much any 12au7 in most circuits.
u mean if we have a 12AU7 we can replace with the 12BH7? what makes it better?
Kegger
R.I.P. 1/12/1966 - 6/1/2017
While specs don't allways tell the story, both the 12BH7 and the ECC99 are flatter
in there frequency response and have less distortion then 12AU7's do, and in most
circuits I find them better sounding as well. (most circuits)
Yes the 12BH7, 12AU7 and the ECC99's all have the same pinout, roughly same gain
and will draw very close to the same current on the B+ side of things, but an ECC99
draws 800ma of Heater current, the 12BH7 draws 600ma of Heater current an 12AU7
is only 300ma of Heater current, so as long as you do have the current available then
all of them can be used in the same circuit.
(Heater current, need to know available Heater current on the units trying these tubes)
in there frequency response and have less distortion then 12AU7's do, and in most
circuits I find them better sounding as well. (most circuits)
Yes the 12BH7, 12AU7 and the ECC99's all have the same pinout, roughly same gain
and will draw very close to the same current on the B+ side of things, but an ECC99
draws 800ma of Heater current, the 12BH7 draws 600ma of Heater current an 12AU7
is only 300ma of Heater current, so as long as you do have the current available then
all of them can be used in the same circuit.
(Heater current, need to know available Heater current on the units trying these tubes)
I would agree that the average 12BH7 is probably as good as, or better than, the average 12AU7, and tube prices typically reflect this. However, the 12AU7 was a much more popular tube, and as a result had a lot more variations produced by a number of different manufacturers. Many of these variants are legendary for their reproduction capabilities and low noise floor. And they were classified by these parameters even when they were being produced.
As an example, 12AU7s were the tube of choice for many high-end organ manufacturers, and these companies qualified every tube that went in to their products. In some cases these tubes were relabeled (like Allen Organ's PN-11), whle in other cases they were simply marked, often with a dab of paint on the glass tip. So you might be hard pressed to find 12BH7s that can easily top the best of the 12AU7s. And the best of the 12AU7s might not always be the usual suspects.
As an example, 12AU7s were the tube of choice for many high-end organ manufacturers, and these companies qualified every tube that went in to their products. In some cases these tubes were relabeled (like Allen Organ's PN-11), whle in other cases they were simply marked, often with a dab of paint on the glass tip. So you might be hard pressed to find 12BH7s that can easily top the best of the 12AU7s. And the best of the 12AU7s might not always be the usual suspects.
Your right about the best not always the usual suspects. I'm using Sylvania 1951 blackplates with bent rectangular square getters in my Foreplay preamp and they smoke all the many that I have tried, including the usual suspects. They are organ pulls labeled Conn. These are premium tubes in my preamp. I've never seen these on the bay or anywhere else and assume them to be very rare. Hope they last a long time.
dividebytube
Well-Known Member
late 1940s/early 1950s RCA black plates. These still show up for decent prices and hey these guys invented the darn things.
overall I prefer the 12BH7
overall I prefer the 12BH7
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