Monday, May 31, 2010

12BH7 Listening Test!

The 12BH7 shares many similarities to the 6SN7 (also a favorite tube around these parts), but is characterized by a darker sound.  In the past, this tube was known simply as a favorite driver for the old Macintosh amps, or as an inexpensive alternative to the 5687 and the 12AU7.   Lately, however, the 12BH7 has experienced a resurgence in popularity as audiophiles have been discovering its remarkable musicality.

Although they are no longer manufactured, there are still significant numbers to be found due to their original use in audio amplification for television as well as in stereo systems.But some of the brands in this category are becoming very collectable… and, as a result, much more difficult to acquire.

Our 12BH7 stock comes from old tube collectors and aficionados who stocked up decades ago. We tested several nearly identical types of Sylvania and RCAs as the metal used in the plates, the type and position of the getter, and the manufacturing process itself can vary and significantly affect the sound.The differences in quality and texture are often more than variances in the individual tubes and so we tried to create a helpful purchasing guide for our customer’s use.

Here are my notes (in listening order) from a recent 12BH7 tube comparison binge.  We listened to Hilary Hahn’s “Barber and Meyer Violin Concertos”.  The asterisks indicate the tubes deemed (with pretty much unanimous agreement) to be the best of the night.  Enjoy!

Amperex 12BH7A (Orange World): Still, unadorned quality. Seems to be a good level of detail throughout the low, mid, and high ranges. Appealing sound, immediate and bright, but slightly thin. 

Sylvania 12BH7 pinched plate from the 60s: Sound is a little richer than the Amperex. A more musical tube as well –rounder and more full. Both hushed and urgent moments are fleshed out and equally affecting.

Sylvania 12BH7 black oval plate from the 50s with U-getter: Lovely. Very musical. More detailed than the Amperex. Very rare. Soft, lush sensuality to the sound. Velvety.

Sylvania 12BH7 black oval plate from the 50s with D-getter:  Slightly bolder, slightly less lush sound but with even higher level of detail. Maybe a little more musical than the previous – first of this selection I would describe as having a “live” sound.

Sylvania 12BH7 grey oval plate with D-getter from 60s: Tested three, all with yellow lettering.  Two were slightly muted. Still detailed in the low and high ranges but the sound didn’t blossom as fully as the previous tube. (Suffering a little, I think, in comparison.) The third had a nice sound but more noise in the high range and still a loss of detail in the big moments through the mid range. Absolutely a nice tube, but doesn’t stand out against the other Sylvanias. 

Sylvania 12BH7 dark grey oval plate with O-getter from 60s and no copper grid posts (red lettering):  Much clearer and more musical. Pleasant, well-modulated detail. Possibly a little noisy in the mid-range, but still one of my favorites so far.

*Sylvania 12BH7 dark grey oval plate with thick O-getter from 60s and no copper grid posts (marked with red top - possibly a factory rating for audio): Very full, rich sound. Can really hear Hillary Hahn’s bowing technique instead of just the grating buzzing that one usually hears with recorded violin (an artifact, I think, of placing the microphones too close and not allowing the sound to expand before being captured). If life sounded this good more people would probably like classical music. Incredibly rich detail. Nicely developed mid range. High notes really sing. Very beautiful.   What stands out upon re-listening to this tube after the RCAs is the comparative delicacy of the sound. Sort of like fresh poached salmon as compared to a juicy steak. Both are good, and the difference in enjoyment is going to depend on personal taste.
RCA 12BH7A square black plate winged plates, U-getter, late 50s: very nice tube. Close second to the last one we listened to. Very melodic and detailed. Some buzz in the larger string sections. Can still hear bowing technique. Tube really does sing.

RCA 12BH7A square black plate with double wings , U-getter, late 50s (white lettering):  Back to the Amperex stillness, which doesn’t compare well with the previous 2 tubes. Still very a good level of detail, almost comparable to the sound of an old phonograph.

RCA 12BH7A oval black plate with double wings, bent D-getter, late 50s (red lettering, green paint?):  Very clear, rich sound. Sings. Something very honest and straightforward about the sound of this tube – you can hear everything that was heard in the better tubes, but the detail seems less modulated. I can see this tube being a lot of fun to listen to on a regular basis. Glorious in the larger sections.

*RCA 12BH7A long black plate with double wings, dimpled square-getter, late 50s (white lettering):  Similar to the last tube, but with many more dynamic levels. Softer details perhaps, but a very high level of detail all the same. Never thought I’d see the day that an RCA blew an Amperex out of the water.

*RCA 12BH7A square black plate with double wings, O-getter, late 50s (red lettering):  Crystal clear sound but still completely filled out. Solid dynamic range. High level of detail. Beguiling musicality.

RCA 12BH7A square grey plate with double wings, O-getter, 60s (red lettering):  Really not quite as detailed, a little noisy. Some real sweetness at the top. A warm tone. Balance is a little off, some parts pop too much and others are too muted.

RCA 12BH7A grey square plate w/ double wings, halo-getter, early 70s (red lettering):  Clear consistent forward sound, good detail, perfectly decent tube. Not at the very top of the list, but stands up well to some of my favorites tonight.