Thursday, February 20, 2014

Tube Review: The Shuguang EL34B pentode

Ah - the legendary EL34 pentode which has been the heart and soul for classic guitar rigs and my first ever tube amplifier, the Dynaco 70.  Developed (with several ancestors) by Philips for PA use, this slim bottle cannot be mistaken for any other tube out there.  Lately this tube - at least in some quarters - has gotten a bad rap as being too warm or not a real audiophile contender, unlike the 6550/KT88 or even (ha!) the 6L6 family.  I strongly disagree with this, thinking the EL34 is one of the most musical tubes out there, walking a fine line between a triode romance and warmth, and the more dynamic sound of the 6550.

The Shuguang "B" version of the EL34 is the stock tube in countless amplifiers and has been labeled Ruby, Valve Art, and who know what else.  It's quite common for new owners to ditch these tubes for something more upscale from the Russians, like the EH, Tung Sol or Genalex "re-issues", or even something NOS like Siemens or Mullards.

There is also the conception that Chinese tubes are prone to blowing up - perhaps a leftover memory from the days of the Jadis JA200 when the Golden Dragon KT88s were referred to as firecrackers.  At least with my experience using the EL34B tube, I've put the hurt on them with the Eico HF-60 monoblocks.  Each tube was consistently taking 500VDC on the plate at 60mA.  That's right on the edge of max dissipation but I never had one blow up.  I'm not sure what modern tube I would trust to take that kind of abuse.

Just for fun, replaced the GEKT88's in the Multi-Valve amplifier with a pair of used and abused Shuguang EL34s from my junk box.  I set the bias point at 60mA which seemed to be the sweet spot.

Listening Test:
For amplifier warmup I listened to my very rare copy of These Immortal Souls - Get Lost (Don't Lie) which has big heavy drums and the chilling guitar work of the ex-Birthday Party member Rowland S. Howard.  The sound is naturally dark and dirgey - this is no audiophile recording - but still incredibly enjoyable.  The bass was big with tons of impact and slam while the midrange had a nice tube "glow" that added to the musical experience.  The treble did, however, seem a tad rolled-off which may or may not be a good thing depending on your speakers.

Neil Young - Live at Massey Hall is a great sounding record.  With the EL34Bs in place I heard plenty of warmth - a bit excessive - that could be a rough analog of the classic Mullard sound.  Where the Mullard still manages to have good detail, the Shuguang lacked in this department.  It wasn't actively annoying - more a sin of omission - but just don't expect to hear everything on the recording.  Nonetheless, Neil Young's voice and guitar work were very natural sounding.  It was the hall reflection and some of the minor audience sound that went missing.

For something more dynamic, I tried out Classic Records re-issue of The Who - Tommy.  The bass and dynamics were very good, but the darkness/warmth was enough to cloud the instrument shimmer, resulting in a less exciting sound.  Depth and instrument placement weren't bad, but nothing close to a vintage Tung Sol 6550 where the images float beyond the boundary of the speakers.  Instead you are left with a closed experience - reminding me of a stock Dynaco 70 that needs to be re-tubed and re-capped - still pleasant but not the ultimate in fidelity.

The Shuguang EL34B makes no pretenses of being state of the art, but it is a good working man's tube - and being available at ridiculously low prices can be used and abused without too much concern.  These obviously don't have the greatest cathode or metallurgy so tube life on these isn't the longest either.  However if you have an old Dynaco 70 laying around or need to retube a friend's Marshall, the Shuguang EL34B is not a bad choice.  I certainly prefer its presentation over that of the Electro-Harmonix (thin bottle) EL34 which, in comparison, sounds like a bad solid-state amplifier.  As always, YMMV.

Review System:
VPI Aries with JMW 10.5i tonearm and SDS Power Supply
Dynavector 10X5
Cardas Cross 1M interconnects
Quicksilver preamplifier with Mullard short-plate 12AX7s, RCA 12FQ7s, Amperex 12AU7
Cardas Quadlink 5C 1M interconnects
Multi-Valve Stereo amplifier
Cardas Hexlink speaker cable
UREI 813A monitor speakers
VTI BL503 equipment rack