12AU7 -a-go-go


Trying to find some good NOS 12AX7s these days is the proverbial needle-in-the-haystack, try as I might, they are all too expensive for NOS or they are used at premium prices. *SIGH*

Brtheren in glass plugs, do not despair for there are some great deals in 12AU7 and 12AT7 NOS tubes. My attention turned to the 12AU7 'cause I had to do the "Tube Righteousness" section for the bargain basement - great performing Classic 9.0 Preamp. The 12AU7 and its derivatives (6189, 5963, 5814 et.al), can still be had at great prices that even a Jack Benny devote will be proud of.

The Classic 9.0 is a great preamp for the money. Solid construction and an external power supply make it one of the quietest preamps ever. Although it is not as detailed, clear or concise and the Doge 8 or the Ming Da MC 2A3, in its price class - it cannot be beat. And, because it took just two tubes, it is a great test bed for tube sound quality. On hand I had a GE 6189, a GE 5963, an RCA 5963, German RFT and a JJ Tesla 12AU7. Here we go, a-go-go......

GE 6189 / Sylvania 6189
These are essentially the same. The 6189 produce a big bold sound. The bass was big and fat and turned the Classic 9.0 into a Dynaco PAS 3X. If you like this kind of sound, then this is the tube for you. Maybe that is why it sounds so good in the Bada DC-222 - as it slightly colors and uplifts the midrange in the preamp section so it does not sound so sterile in the amplifier section.

German RFT 12AU7
The German RFT was the complete opposite. It was polite, smooth and accurate. In a sense, it made the Classic 9.0 slightly boring and uninteresting. While it did not veil the midrange, it brought out the Classic 9's short comings and the sound stage was very flat and the bass anemic. This tube is probably a great bet for the Ming Da MC-7R, where toning down some of the tubey-ness of that preamp would be a plus. It would be terrible in the Bada DC-222, my guess, and it would make it too sterile, well, too German.

JJ Tesla 12AU7
The Teslas were an over-all, well rounded performer. They did not excite nor dull. They did make the sound a little velvety and greasy in the midrange. Use these in a system where it sounds a little harsh and tranistory to you. They perform well in the Bada DC-222. They may make the Ming Da MC 7 a little too smooth - so unless you like that sound consider other choices.

GE 5963
As far as the Classic 9.0 goes, this tube is one that I can live with. It is smooth and detailed throughout the midrange and delicate in the highs. It has a slight bass hump, and while it is not fat in the bass, it is a little pudgy. It had one of the best instruments and space placements and really let orchestras play through. All in all, it turned the Classic 9.0 into a different preamp. Use it in the Bada DC-222 if you want a more accurate sound with tube warmth and detail. It matches well in the 7R as it lets the rectifying tube perform its magic without too much interference.

RCA 5963
The RCA one ups the GE in terms of spacial acuity, high end articulation and detail. The bass is tighter and firmer, but not lean. Use this in the same way you would the GE. In the Classic 9.0, it was my favorite and the one I recommend (while they last).

All the best,

Vic

P.S Look for the Launch of my social network, "The Halo Getter", where we will discuss Audio, tubes, the high end industry and other fun-sense.