December 2002

Sweet n' Low
Bottlehead's $549 Paramour 2A3 Monoblock Amplifier Kits
Review by A. Colin Flood
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  An audiophile is not merely someone that Dictionary.com says has "ardent interest in stereo or high-fidelity sound reproduction." An audiophile is someone who wants to do something about the flaws and deficiencies in their home entertainment system, whether it is about the music or the movies. A tweaking audiophile is someone who wants to make some or all of those improvements themselves. (This term derives from a caustic description applied to myself. As in the time when an annoyed salesman said, "what are you anyway, some sort of xxxing audiophile?" His expletive evolved in print to "frigging," which lead to "freaking" and then to "tweaking." And, there you have it. Lemonade, from lemons.)

Ask a tweaking audiophile about solid-state amplification and you receive descriptions of tight, powerful bass, a sizzling top-end and an overall neutrality or cleanness that embarrasses the warm and fuzzy feelings of tube amplifiers. Yet, scratch an avid "tube-o-phile" and you hear vociferous imagery about three-dimensionality, palpability and musicality, with an absence of solid-state's dry, austere or clinical "nasties." Followers of the tube sound wax poetic over the lush midrange, the sharp treble and the delicate contrasts of the details.

Tubes have a mystical reputation among many audiophiles, part well deserved, part superstition. It's true that, in general, tube amps tend to have simpler circuits than do solid-state. If you wander the halls of the Enjoy the Music.com™ site for any time now, you will see that I wallow in the low-end of this hobby. I deprecate the gifts from Mount Olympus, while at the same time extolling the virtues of such head turning bargains; such as the $99 ASL Wave 8 tube amplifiers (yes, $99!), and the unbelievably charming $279 Axiom M3Ti bookshelf loudspeakers.

Therefore, it should come as no surprise that last year I decided that delicate flea-powered tubes would be the absolute best possible amplification for my big old horns (see my Bio for the context of my reviews. Of the different styles of tubes available, the one type that kept coming up as the tone king of choice for ultra-sensitive horns was the 2A3 triode. This is a common, readily available, modest price mid-size bottle containing an anode, a cathode, and a control grid. So I sought not only the lowest cost 2A3 amplifiers available on the market today, but also models that can be constructed by tweaking audiophiles. Am I not cheap?

This search lead me to the bargain basement forums of the Bottlehead Corporation and their newly planned 2A3 Paramour kits. Tubes are nicknamed bottles. Tube-loving audiophiles are therefore bottle heads, hence the Bottlehead appellation of the firm. The Bottlehead Paramour kits do not cost as much as most amplifiers on the market. They are a bargain basement bonanza at only $549 for the pair. This makes them not only one of the lowest cost tube amplifiers you can buy, used or new, but the lowest cost 2A3 amplifiers that I know of... period.

Description

The Bottlehead 2A3 Paramours are a pair of low-powered hobbyist tube amplifier kits. They are monoblocks - one amplifier per channel. They have an attention to attack, detail and tone that rivals far more expensive solid-state amplifiers, if used with super or ultra-efficient loudspeakers rated at 95-dB/w/m or more. For tweaking audiophiles, who know which end of the soldering iron to hold, the $549 kits provide the least expensive way to enjoy one of the audio industry's masters of tone and texture! In fact, at this low price, the Paramour kits compete with only a few other tube amplifiers, either assembled or in kit form. Most new amplifiers, and most used ones too, are more expensive than these.

The Paramours do indeed look like a do-it-yourself (DIY) kit. The amplifiers are new products from Bottlehead to replace their first single ended experimenter's kit in 1996. Mine are one of the first assembled and upgraded Paramours sold by Bottlehead. The amps came in light tan Alderwood enclosures the size of tissue boxes. All of the Bottlehead models share the same top plate chassis for mounting the hardware of the various. All of the tubes, transformers, and connections stick out of the top plate. Therefore, the various Bottlehead kits resemble each other. 

The Bottlehead 2A3 Paramours do not look or feel like your typical off-the-shelf receiver in the same price range. They are not sleek black boxes. They do not fit easily into the stereo rack, if at all. The Paramours seem to have no front, back or sides. There is no protective cage to dissuade prying youngsters from the enticing blue luminescence of the softly glowing tubes. Connections come from each corner. They have some of the largest gold binding posts of most amplifiers or loudspeakers (an especially important feature for reviewers constantly changing equipment). The gold posts stick out of the top in one corner, while the power switch is on the other corner. The stiff power cable is an inch wide. Its three green and black wires weave back and forth like some primitive DNA strand. The power cord comes out yet another corner. Not one side or the other looks like the front or the back.

The exposed chassis is a brushed aluminum plate. Underneath is point-to-point wiring with high purity long crystal copper magnet wire for the ground buss. The wiring is simple with only a few dozen connections. It looks about high-school level in complexity. For tweaking audiophiles, one of the charms of a point-to-point amplifier, and certainly a hobbyist kit, is that the wiring and components are quite easy to modify. 

The amplifiers are puny compared to their task. They resemble a small antique steam engine strapped to the diesel task of moving the Klipsch freight train. Yet, the four little tubes can crank the big old horns. The delicate contraptions can rock Melissa Etheridge or Delores O'Riordan well above the painfully loud 100-dB level, as measured at the listening spot.

Cute Custom

Bottlehead made some upgrades to the standard kit on my units. The load boards, spike filters, cancellation circuits, coupling caps, thick gold binding posts, stiff interwoven power cables and finish are all additions to the standard kit. My units are look quite different than the picture. The transformers and top plate in my custom kits are burnished rust and suede green; the driver tube and transformer leads are sheathed in copper tape. Upgrades will add about $100 to the pair. Bottlehead produces the kits when they get the order, so allow about five weeks before the amps are actually shipped.

There are no circuit boards. No op amps. No complicated signal paths. That is one reason Single Ended (SE) amplifiers sound so good, they are simplicity personified. Circuit topology is simple and effective point-to-point, hand wired and Class A. Tube amps require an output transformer, which is an awful lot of wound-up wire to be putting between you and your music. Tube power amplifiers need output transformers to couple their high impedances and voltages to speakers, which operate at low impedances and lower voltages. There are a few output transformer-less (OTL) tube amps on the market, but these are expensive and rare exceptions.

The antediluvian Paramours use a single 12AT7 tube as the drivers. The driver tubes couple to the 5" high Valve Art 2A3 bottles. The tubes are not run "hot," for increased output. Bottlehead estimates their useful life at two to three years. There is no biasing required. Other tubes may used with minor modifications. There are no other controls on the Paramours, except for the small black rocker switch for power.

The 2A3 tubes (one bottle per monoblock side) operate in a parallel-feed output mode. The parallel-feed circuit keeps the DC on the output plate of the tube, out of the output transformer, without using a capacitor or transformer directly in the signal path. Bottlehead says the parallel-feed output gives the amp a remarkable sense of realism, bandwidth, and bass articulation, particularly considering the price. The parallel feed idea is not unique. The idea is to reduce the cost of the large transformers. It means that a smaller (2.5"), less expensive power transformer can be used. 

The Paramour power supply uses ultra-fast soft recovery rectifiers and a C-R-C filter. Metal film resistors and polypropylene capacitors are in the signal path. The filaments are AC and a hum balance potentiometer is employed. The parallel feed coupling capacitor is a Solen type. Input impedance is 270k Ohms. Output taps are 4 and 8 Ohms, but the amps can be configured for 16 Ohm loudspeakers.

Assembly Required

Bottlehead shipped the amps snuggled in a molded bed of poured Styrofoam. Very smart. (I kept the boxes, of course). The manual is brief and to the point, yet it appears complete. My assembled amplifiers arrived with ledger-size color photos of the underside. The pictures are so large that each fold is as big as a single page. 

Upgrade parts and information for the Bottlehead 2A3 Paramours are readily available by Internet forum, telephone or by e-mail. The support on the Bottlehead forum is excellent, with many active and knowledgeable posters upon it. Responses to my questions were quick, friendly, and informative. With Bottlehead's west coast time zone, which is three to four hours behind, customer service and help during early evening hours (after work) was easily accessible from an eastern time zone. A nice feature for tweaking audiophiles who do know how to use a soldering iron.

Like all other tubed or sensitive equipment, Paramours sound better when placed on very solid and isolated footings, such as the vibration isolation platforms that I created here. Allow one to two feet of cooling air on all five sides of any tube or hot component.

Once assembled, the Bottlehead 2A3 Paramours are one of the best sounding amplifiers I have heard, and certainly one of the best matches available for Klipsch's enduring classics, their 40's style corner horn. When crammed into a corner, these 167-pound triangular 3-way hulks are ultra-efficient, at an amazing 104dB/W/m and produce low moaning groans of bass down to 30Hz. They are also fairly smooth, with most of their in-room frequency response in the 2dB range.

My initial impressions have not yellowed over the past two years. There are measurable things that SS amplifiers can accomplish with loudspeakers, especially cone driven ones. But not even the best rig I have heard in my home or in showrooms, compares to the ease, details, textures, tones and "rightness" for such a low price as these antediluvian amplifiers when they are coupled to the largest of Klipsch's big old horns.

In the midrange, the Bottlehead 2A3 Paramours are a sonic delight. The amplifier never trowels the notes on thickly, but applies them with a quickness, lightness, immediacy, smoothness that makes listening an enticing pleasure. They let you enjoy the music. This attention to detail was proven by many loudspeakers. The Axioms M3Tis, mentioned above, but especially the blue-marbled Omega TS1s. So far I like the Bottlehead 2A3 Paramours less with the solid cherry Coincident Triumph Signatures (coming up next month) than the Classic Audio Cinema Ensemble horns (following soon after). 

Bottlehead 2A3 Paramours imaging, with super-sensitive loudspeakers, was enhanced by another quality, one more difficult to describe. A quality of openness and warmth in the upper midrange and treble that's especially evident with female vocals. In this regard, the diminutive amplifiers can compete with even powerful behemoths like the incredible Pass Labs Supersymmetry™ Balanced Single-Ended Class-A X250 stereo amplifier. 

The openness in the upper midrange and above is a result of the details, speed, clarity, and coherence of the Bottlehead 2A3 Paramours' presentation. Leading-edge transients were snappy and startling but never exaggerated. And the energetic pace, timing, and energy pulled the rest of the acoustic envelope smartly along behind it: bloom, harmonic interplay, and decay were beautifully rendered.

Comparisons

Yet, as delicate and refined as the tone and texture of Bottlehead 2A3 Paramours can be, especially the smooth mid and upper ranges, the antediluvian style amplifiers are not suited to a wide choice of loudspeakers. The wide and deep range of the leaning Newtronics Skates towers made them one of the favorites, but they were not well suited to the Bottlehead 2A3 Paramours. Neither was another favorite. The big brother Axiom Audio M80Ti is an almost excellent bargain of a loudspeaker: six drivers in each column for $1,100 a pair, delivered to your door! Yet they too need the extra control of a SS amplifier, or even better yet, a second bi-amplifier. Without it, the midrange on both of them can sound quite nice, but the feeling you have is that of wishing for something more. With the Bottlehead 2A3 Paramours on these loudspeakers, I found myself dialing up more and more volume to get something more out of the loudspeakers.

They do sound very good with most loudspeakers; with a good attention to detail, a mid-range warmth and high sparkle that rivals the best amplifier I have auditioned (Pass' solid silver block of 250 watts). They do not have the ooomp to power the low bass, therefore I do think they need some solid state support in the mid and deep bass regions (even though the Klipsch Khorns with the Paramours do measure fairly fat down to about 30Hz.)

On the Enjoy the Music.com reviewer's scale, a score 50 is passing, about average. Grading my SS amplifiers and receivers, the Wave 8s and the Pass X250 against each other in the same classroom, the Bottlehead 2A3 Paramours are above average in many respects with ultra-sensitive horns, but only average in many respects with more normal fare. A score of 90 means that only money-is-no-object (yeah, right!) combinations, such as amazing Avant-garde horns with Viva amplifiers, could possibly do better. 

I have to give the Bottlehead 2A3 Paramours a low score in the sub-bass category, because my both SS Pioneer, and the impressive Pass x250, did a better job there. They both added that extra creamy icing, on cone loudspeakers, which makes the bass cake so sweet. The Pass, of course, was superb on all loudspeakers used. The big old horns however have little need of the Pass X250's boundless energy. While the Pass X250 excels at everything, tweaking audiophiles interested in the Bottlehead 2A3 Paramours should not envy this $6,000 amplifier. There are many things, such as quickness and tone, to recommend the much lower cost Bottlehead 2A3 kits over the mighty Pass amplifier, when you have super-sensitive speakers! 

I also have to give my units a below average score in the noise category too. Because with the big old horns, I can hear some faint hum. Bottlehead says they updated the original circuit to incorporate a C4S active load on the driver stage. This will significantly decrease noise and hum levels, they say, and increase the linearity of the driver stage. The previous version of the kits averaged about 20-30mV RMS hum with Valve Art 2A3s (same as mine). With the C4S update, the hum level should be significantly reduced, to only 2mV RMS. I add my own category, enjoyment, to the Enjoy the Music.com™ rankings, to reflect my overall emotional response.

Two strong competitors for the Bottlehead 2A3 Paramours are the $99 Wave 8s, mentioned above, and the nOrh SE9 integrated amplifier (review due this month, but coming soon). The nOrh (pronounced more, with an "n") is a good-looking new unit, imported from Thailand by the same company that makes the round marble loudspeakers. At only $499 for a pre-amplifier/amplifier combination, assembled and shipped to your door, this hefty (38-pound) unit can handle only two inputs and yet sounds somewhere in between the dynamic Wave 8s and the detailed Paramours. 

Considering their price, the Bottlehead 2A3 Paramours are very good bargain in a tube amplifier. Considering their 2A3 tube component, they are an excellent choice. The other, pre-assembled models, which I would seriously consider for super-sensitive loudspeakers, are Wright and Welbourne amplifiers. Their models compete for first place in my dream systems.

Specifications

Power Output: 3.5 watts, with 5% THD, at 1kHz

Tube Compliment: 12AT7 for driver and 2A3 for output per monoblock

Input Impedance: 270 kOhms

Output Transformer Taps: 4 Ohms, 8 Ohms

Frequency Responce: 25Hz to 37kHz (±3dB)

Price: $549 per pair in kit form

Company Information

Bottlehead Corporation
2202 NW Bucklin Hill Rd
Silverdale, Washington 98383

E-mail bottlehead@bottlehead.com
Website: www.bottlehead.com