The deHavilland Electric Amplifier Company
Review By Dick Olsher
My theory is that over the years preamplifiers have been indirectly responsible for more audio grief than any other hi fi component. It is literally a stealth sonic offender, because so few audiophiles realize the mediocrity that lurks in their front end. More money has been wasted, in my estimation, in futile attempts to fix what is actually a front-end problem with downstream tweaks. Imagine the expense showered on exotic interconnects and speaker cables, when all that money could have gone toward a better sounding
pre-amplifier. Many find comfort in owning a highly touted brand name or an audio classic. Well, please take note of the following personal observations, spanning a time frame of 35 years. With only a couple of exceptions, solid-state
pre-amplifiers, regardless of price or prestige have failed to move me musically. Only a handful of tube designs have passed my criteria of excellence in the areas of resolution, dynamics, and transparency. And that grouping certainly does not include any vintage tube gear. Avoid McIntosh, and incidentally, I find the Marantz 7 to be more about hi fi than music.
If you are looking for multiple gain stages, high part count, circuit boards, or tone controls, look somewhere else. The unit is fully hand-wired, in point-to-point fashion, and minimalist as far as parts count. There is only one gain stage, followed by a cathode follower stage. Hence, not only is the gain a modest 12dB, which should be adequate for line inputs such as CD players and FM tuners, but the unit also inverts polarity. The latter means that a positive going input appears as a negative going output. This is not something to fear or distrust and can easily be dealt with. All that is required as compensation is an additional polarity reversal in the signal path. In my system, I simply reverse the speaker leads at the power amplifier outputs. At first glance it may appear that there is no balance control. However, tucked along the rear top plate are two trimmer controls, which give Left-Right balancing adjustment, by tweaking the output of one channel relative to the other.
A premium member of the family is the industrial-grade 5692, the most sought after type being the RCA redbase series. A nifty feature, much appreciated by a chronic tube roller, is the ease with which octals can be substituted. Thanks to its keyed base, octals may be rolled in without sight of the socket. The popularity of the 6SN7GT is well deserved thanks to its ability to portray a vivid palette of harmonic colors and kick-butt dynamics, qualities that well suit Ms. Chaffee's musical priorities.
The power supply is well filtered and features tube rectification. The directly-heated 5AW4 rectifier tube draw an impressive 3.7A and would normally see duty in a power amplifier. But this is precisely the correct strategy for authoritative
pre-amplifier sound: treat the thing like a power amplifier. Exceptional passive parts abound: Cardas Litz wiring, mil-spec paper-in-oil capacitors, Roederstein resistors, and a beautiful Goldpoint stepped attenuator that eliminates a few layers of soundstage veiling relative to the industry standard conductive plastic potentiometer.
The UltraVerve's single gain stage lives and dies by the choice of 6SN7, since the
pre-amplifier is adept at revealing differences between the good, the bad, and the ugly. Fortunately, the stock tube is a select vintage type. My unit was shipped with a Sylvania "chrome top," an excellent vintage brand, though due to limited supplies other brands may be substituted at the factory. The "chrome dome" is fairly easy to locate, and features a warm, detailed midrange. It comes close to equaling the magic of my favorite RCA smoked-glass (grey RF shield sprayed on inside of envelope) VT-231, but falls short in terms of dynamic nuances and vibrancy of timbral colors. Note that the RCA VT-231 is a 6SN7-GT type, which is my opinion is the premier type worth hunting for, as it denotes the original version of the tube, and most likely a production date prior to the TV era. Beware, there are 6SN7 types to avoid at both ends of the price spectrum. The affordable new production Russian types are definitely in the ugly category, while the much hyped RCA 5692 redbase was a definite disappointment - at least in this context - with a rather bland harmonic disposition. What follows is based on extensive auditions using the RCA VT-231.
About 20 years ago the great J. Gordon Holt pronounced the sound of the Berning TF-10 pre-amplifier so exemplary as to make further advances in the art unnecessary. That judgment has proved to be premature, so wisely I will not go that far. But having lived with some of the elite high-end pre-amplification from the likes of Jadis, Sonic Frontiers, and Air Tight, the deHavilland UltraVerve is currently my first choice in line amplification. At a retail price of $2,495 it upsets the ultra high-end applecart; the point being that simple, minimalist, well-engineered designs can rise to the top while being quite affordable. Low on parts count, but high on tube magic, the UltraVerve scores big in my book.
Bandwidth: 20Hz to 80kHz
Maximum Output: 30 Volts Push-Pull
Voltage Gain: approximately 12dB
Signal Triodes: 6SN7 GT, GTA, GTB, WGT
Rectifier Tube: 5AW4 rectifier tube
Signal To Noise Ration: 85dB
Inputs: four stereo
Outputs: two stereo
Input Impedance: 50 kOhm
Output Circuit: Cathode follower; minimum 10 kOhm load recommended
Dimensions: 18 x 11 x 6 (WxDxH in inches)
Weight: 15 lbs (shipping)
Power Requirement: 115 VAC/60Hz, 40 Watt consumption
Warranty: Two-year parts; one-year labor; 90-day on tubes. Warranty is not transferable.