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發表於 2016-10-20 11:23:33
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Audion Sterling EL34 Anniversary Integrated Stereo Amplifier
review at TAS by Dick Olsher
History has been kind to Audion since Erik Andersson and David Chessel started the company in the late 1980s. It survived two decades in an age when the average lifetime of a startup high-end-audio company was less than five years. In 2000 Graeme Holland took Audion over from Chessel and moved operations to France’s Bordeaux region where he happens to live—in fact, to a large barn attached to the side of his house and converted into a custom-manufacturing facility. The transition was eased by “coercing” some of the Audion staff to move to France and continue working for the firm. That barn is now a working factory of 3100 square feet, of which 860 square feet are factory space and 430 square feet are devoted to transformer winding, baking, and testing.
Graeme tells me that since he took over Audion there have many improvements made to the product lineup based on market research, customer feedback, and dealer-led requirements. The $3499 Sterling EL34 Anniversary stereo amp is a sixth-generation product. Not only has the chassis been changed considerably from the early steel variety, but the circuit design has changed as well, as has the topology of the output transformer. Many of the internal components are now being made specifically for Audion, which manufactures all the output transformers in-house. Audion also prides itself on using components sourced from either Europe or the U.S. when possible, and is eager to maintain product quality and reliability. Where single points of failure have been found in the past, the circuits and/or parts have been over-engineered or over-specified to avoid such problems in the future. There are no production lines at Audion. One person builds an amp from start to finish, as experience has shown that such an approach engenders more pride and care during the assembly process.
Audion today continues to adhere to a basic philosophy of making affordable esoteric high-end equipment available to everyone and not a select few with deep pockets. Graeme says that he personally prefers “a system that is non-fatiguing and musical to an extremely analytical system where you crane your ears to listen to what they are saying in the background of Jazz at the Pawnshop for example [or] where a guy on a mixing desk didn’t properly change a level or a drummer dropped a stick. Our high-end products will retrieve this info and more, admittedly, but I maintain that a good amplifier is not only transparent but musical and engaging and a pleasure to listen to for a whole evening and more. I believe our amps are primarily musical.”
There are several versions of the Sterling EL34 Anniversary stereo amp. One uses a printed circuit board (PCB), another a hard-wired circuit. Another difference is packaging: One version is capable of switching up to five line-level inputs; another, more basic version has only a volume control. All versions are single-ended (SE) designs using a single EL34 per channel in pure Class A operation. However, the PCB version of the Sterling uses a Russian 6N1P dual triode as a voltage input/driver stage, while the hard-wired version uses the 6H23N, another fine Russian dual triode. The power supply is solid-state-rectified and uses a good quality CLC filter network. All filament supplies are AC.
The output stage is cathode biased for long-term stability. What is unusual though is the ultralinear (UL) connection, which is typically seen in a push-pull amp, but of course is also very much an option for single-ended pentode designs. The screen grid is connected to a tap on the output transformer so that AC screen current provides a form of power feedback to the output stage. The end result is an operating characteristic intermediate to that of triode and pentode, meaning that linearity is increased and distortion is reduced. There is also a bit of global feedback used for increasing the amp’s damping factor. Graeme tells me that the idea of single-ended UL dates back to Erik Andersson’s early days, in actual fact before Audion. Erik’s first design using this principle was apparently for Audio Innovations in the early 1980s. And the design was carried forward after Audion was formed. (I never understood the logic of trying to use a pentode or beam power tube without UL in a single-ended output stage. Yes, the payoff is increased power output relative to a triode, but tetrodes and pentodes are so inherently non-linear that they need help or else distortion products dominate the sound.) The Sterling EL34 Anniversary delivers 12 clean watts into an 8-ohm load. It is said to be suitable for use with loudspeakers of 89dB sensitivity or better. Note that only 8-ohm impedance taps were provided on the review sample; thus I would avoid using it with 4-ohm rated speakers, unless their sensitivity is well into the 90s. When ordering, however, you may specify 4 or 8 ohm transformer taps at no charge, or with selectable taps for a $70 up-charge.
The stock EL34s are Russian Electro Harmonix, and my advice is to simply leave them alone. My one tube-rolling experiment using reissue Mullard types did not improve matters at all. The thing is that the Audion sounded good right out of the box. In fact, I couldn’t get it to sound bad with any of the speaker loads I threw at it. Initially, though only briefly, it partnered the Volent VL-2 SE and made a good impression at the frequency extremes—not an easy task for many tube amps, and especially SE designs which make life much more difficult for the output transformer. A practical consequence for many commercial SE designs is bandwidth limitation, manifesting itself as deficient bass reach and a power bandwidth barely hovering around 20kHz. That’s sufficient to round off transients and liquefy harmonic textures to the point of emulating the crunch of soggy toast. Therefore the Audion’s performance at the frequency extremes was a pleasant surprise: SE magic all right, but with good control of bass lines and naturally liquid textures that did not cross the line into gooey and mushy territory.
The Audion spent most of its time partnering the Zu Audio Omen Def (98dB sensitivity) and my Basszilla Platinum Mk2 (96dB sensitivity) speakers. In this high-sensitivity context, 12Wpc proved more than adequate headroom, and I might add that even in such a setting the noise floor was low enough to be unobtrusive. Soundstaging was 3-D with excellent depth perspective, though transparency was a bit lacking relative to far more expensive amplifiers. The subjective impression was of slightly recessed highs, which shifted the tonal balance towards the lower midrange. The result was a full-bodied authoritative presentation with a benign distortion spectrum that facilitated long-term listening enjoyment. The Audion’s grasp of space and time was exceptional and never on better display than when it partnered with the Zu Audio Omen Def. The synergy of pure Class A and full-range drivers borders on the magical and made for a totally engaging emotional presentation. The Audion was not a detail champ; it did not plunge my ears deep into the mix, though it was able to retrieve far more low-level detail than other amps at its price point.
The Audion Sterling EL34 Anniversary Edition is a warm and dimensional-sounding amplifier with a potent lower midrange that does justice to the power range of an orchestra. It sang right out of the box and never misbehaved. Kudos to the Audion team for breathing new life into the venerable EL34 pentode. In my estimation, the Sterling EL34 represents a gift to music lovers everywhere. Highly recommended.
SPECS & PRICING
Power output: 12Wpc, Class A into 8 ohms
Recommended load: 8 ohm nominal
Distortion (at 1W): <0.1% with no feedback
Frequency response: 14Hz–40kHz +/-1dB
Sensitivity: Variable, >200mV for full output
Noise: <– 85dB (CCIR)
Power consumption: 140W
Tubes: Two EL34, two 6H23N
Dimensions: 9.1" x 7.5" x 16.5"
Weight: 31 lbs.
Price: US$4098 (US$3499, non-integrated version) |
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