Pacific Creek — the company — is the new kid on the block, in business only since October 2003. You cannot say that, however, about its founder and chief designer, Jerry Wang. He has been actively building tube amplifiers for over 30 years, having built his first tube project when he was only 13 years old. With a technical background in radio circuit and system design, and digital signal processing, the transition to high-end audio combines Jerry's engineering skills with his passion for tube sound. The Separo SE300I represents Pacific Creek's inaugural product, a 10 watt per channel integrated stereo amplifier — a single-ended triode design featuring the ever-popular 300B power triode. The gold-anodized front panel and elegance of finish in general suggest a lofty retail price. Its actual retail price ($1899) should turn more than a few heads, and is only possible because the Separo, while designed in the US, is being manufactured in China.
The output stage consists of a Chinese 300B-98, self-biased for long-term stability. The output transformers are said to be oversized and capable of handling nearly 20 watts in single-ended operation. The primary's impedance is 3,500 Ohm, which is on the high side of the optimal load for a 300B, but was chosen to provide a damping factor of about 6. Secondary winding taps are provided for 4 and 8 Ohm loads. No global or local negative feedback is used. The power supply is vintage-tube in conception with a modern touch thrown in: tube rectification using a 5Z3P (a Chinese 5U4G equivalent), a choke input filter, and a DC supply for the 300B filaments.
I did experiment with substitutions for the Chinese 12AU7 and 300B output tubes, but I did not touch the Russian 6P3. The most transforming tube roll-in turned out to be the KR Audio 300B Balloon. Image focus and stage depth perspective improved, textures became sweeter and more luxurious — just what a old tube romantic needed! The moral of the story is that the Chinese 300B-98 does not appear to work well in this context. And there is no reason for prospective customers to be forced to purchase this tube. A more customer-friendly policy would be to provide for either 300B alternatives or optionally sell the amplifier without output tubes.
It was now time to take stock of the situation. The soundstage was reasonably well reproduced, with convincing width and depth, but lacked adequate projection into the room. Image focus was very sensitive to absolute signal polarity. With the "correct" polarity setting, however, instrumental outlines snapped into focus resulting in good spatial resolution. Bass lines were not reproduced with the tightness and control of solid-state amplification, but certainly the Separo was no better or worse in this regard than many other SET amplifiers. Treble extension was very credible for a SET design. I am certainly not a fan of an overly liquid and dark presentation, which is symptomatic of a severely restricted power bandwidth. The Separo managed to project a "sunny" disposition with good treble detail. For example, Ernestine Anderson's rendition of "What a Diff'rence a Day Made" [Never Make Your Move Too Soon Concord Jazz CJ-147] came through with crystalline enunciation. However, the tonal balance was not entirely to my liking, being a bit recessed in the midrange.
So far pretty good. But storm clouds were gathering on the horizon. It has been said that a life is not measured by the number of breaths you take but rather by the number of moments that cause you to hold your breath. It became clear that with the SE300I in the chain, those moments were precious few; the music's tension and drama were being substantially siphoned off. Imagine a taut balloon that is suddenly pricked by a pin. The explosive pop and subsequent startle reaction are due to the sudden release of pressure. It was as though the Separo was allowing the air to leak slowly out of the balloon. Hair-raising performances were turned pretty mundane. A couple of examples are in order. A young Joan Baez gives a deeply haunting performance of "House of the Rising Sun" [Joan Baez Vanguard VSD-2077], a ballad of a girl gone wrong. Instead of being riveted to my seat, I was fiddling with the volume control trying to coax more drama out of the music. The lack of dynamic scale was also painfully apparent during Walton's Belshazzar's Feast [EMI AN-324]. André Previn whips up the massive forces of the London Symphony orchestra and chorus to imposing levels of dramatic intensity. The Separo simply failed to negotiate the transition from loud to very loud. It could not shift gears fast enough to keep up with the action. There are imperfections I can forgive in reproduced music, but this is not one of them. Take away the emotional underpinning of the music, and what's left of reproduced music is nothing but a canned, uninspiring copy of the real thing.
The mystery began to unfold one day, when we tried to burn in an E34I (our entry level EL34 amp) and did a quick side by side comparison to the returned sample. The humble E34I clearly outperformed the returned SE300I sample. This kept us busy for a while and we finally realized that the sample we sent to Dick had excessive bias which in turn caused core saturation in the output transformers. The "thorough" test (we thought it was) simply could not catch the failure that Dick was able to detect with his ears.
We are sending a replacement unit to Dick and hope he has time for a follow up review. Needless to say we are also adding steps to prevent the same failure from happening in the field again.
Power Output: 10 Watts rms per channel
Total Harmonic Distortion:: <1% at 6 Watts; <2 % at 8 Watts; <5% at 10 Watts (@ 1kHz, 8 Ohm)
Frequency Response: 17Hz to 27kHz (-3 dB); 30Hz to 17kHz (-1dB)
Background Noise Level: <3.5 mV rms. at 8 Ohms
Input Impedance: 47 KOhm
Dimension: 17 x 15 x 8 (WxDxH in inches)
Weight: 68 lbs.
Voice: (425) 961-0136