Product Review - Bottlehead Paramour Monoblock Single-Ended Class A Triode Tube Amplifiers - April, 2001

Colin Flood



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

Tube Compliment: One 12AT7 Driver, One 2A3 Output Tube Per Monoblock

Input Impedance: 270 k Ohms

Output Transformer Taps: 4 Ohms, 8 Ohms

MFR: 25 Hz - 37 kHz ± 3dB

MSRP: $549/Pair in Kit Form

Bottlehead Corporation, 2202 NW Bucklin Hill Rd, Silverdale, Washington 98383-8303; E-Mail [email protected]; Web 


Disc after disc, I made note after note, filling page after page. The sensuous Diana Krall CDs showed off the woody timbre of the bass strings, even the dry parting of her lips. Paul Simon’s “Rhythm of the Saints” displayed a virtuoso interweave of South American percussion. The voice of Sting never sounded better. With one disc after another, I tried to pinpoint tangible differences between the Single Ended Triode (SET) amps, each with a single 2A3 tube, and the Pioneer 30-watt solid state reference monster they replaced. Both of them are Pure Class A amps.

Never before have I delved so deeply into the sonic differences between one tweak and another, between one piece of equipment or another. In fact, as the "discology" continued, my sloppy notes ran into 15 free-hand pages. It was not a challenge noticing the differences – they were clearly there, right from the first note – it was an ordeal describing something so elusive that readers might not imagine it on their own systems. It was a daunting task. I sought to portray the ethereal quality, in scientific terms, by which readers might draw valid conclusions. Any observations I make should be obvious to other readers doing the same comparison.

The 3.5-watt Paramour amplifiers are hobbyist kits. I purchased the amps without any prior listening. Paramours are available as monoblocks (each with a separate chassis) from Bottlehead Corporation (BC). They host a robust forum on the Web as Doc Bottlehead:

Since I can not tell one end of a soldering iron from the other, I ordered my amps pre-assembled. Kit #11 came with a thin aluminum bottom plate for safety reasons (mine). Doc Bottlehead does not have production run. Rarely do they assemble kits, though these units were assembled for picture purposes and me. In fact, one of my amps is in BC pictures.

Doc Bottlehead made some upgrades to the standard kit on these 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. The transformers and top plate in the custom kits are burnished rust and suede green; the driver tube and transformer leads are sheathed in copper tape. The photo above shows all the parts laid out. No circuit boards. No op amps. No complicated signal paths. That is one reason SE amps sound so good. Upgrades and assembly both add about $100 to the price for a pair of monoblocks. BC produces the kits when they get the order, so allow about 5 weeks before the amps are actually shipped.

The amps are as light as a stack of CDs, as delicate as your grandmother’s glass vase and as out of place in the modern stereo rack as a hand cranked cider press in a kitchen. Compared to my 48 pound Pioneer pile driver, these antique style amps are six-pound lady size finishing hammers. Odd looking perhaps, but adorable nonetheless. So adorably cute that my Paramours are now the wallpaper on my home computer. Notice the underside of an assembled amp (shown above). Simple, simple, simple.

First, how they sound

I envisioned writing one of those smoothly elegant pieces for my review. You know the kind. The ones that gush over the nuances, details and emotional impact of some exotic piece of equipment that runs like a Porsche and costs just as much. Yet, here I was, after years of considerable ‘Net surfing and agonizing, mating a bargain basement set of Doc Bottlehead’s tube amps with some big old Klipsch horns. The amp and speaker combination does not cost more than some fancy audio accessories, but it is one that depletes the annual Flood family budget for stereo stuff, so the purchase was of critical importance.

I mean, come on! It is after all, just a stereo system. No living room stereo system could thrill me to the bones as live music making does. Not even the amazing Nearfield Pipedreams with 36 drivers and 4 oil-drum size subwoofers powered by seductive Joule Electra output transformer-less (OTL) tube amps. Not when compared to the megawatt chest thumping and concrete floor vibrating dynamics, or the sheer horse-powered pitch and rhythm, of a jumping band on a nightclub stage. No home stereo is as thrilling as that.

Though I am not the literary gushy type, I am thrilled with my diminutive new toys - as unusual as they are. There is something so “right” about their sound. I am as excited as a schoolgirl at cheerleader try-outs. While I can not easily describe the objective differences, I do refrain from nervous giggling.

What is so thrilling about the Paramour performance?

First, on a pair of big old Klipsch Cornwall horns, with a 100 dB/w/m sensitivity, in a 17' by 27’ carpeted living room with cathedral ceilings at normal listening levels, the 1950s style combination is delicious, delicate and, well …right.

Second, normal volume level can be higher with the Paramours in place. On test CDs, the 9:00 position measures about 67 dB at the arm of my listening chair. Average music on a slow scale is a few decibels above that. On the preamp dial, 8:00 is the battleground between “little miss sensitive ears” (my wife) and when the ultra-clean M-22 solid state (SS) amp is in place. On my preamp dial, 8:00 approximates ¼ of the amplifier output. This is the point where she turns the music down. At 9:00, or even 10:00 on the dial, the Paramour amps will push out coffeehouse SPLs: levels slightly above normal conversation. The reason is that with a mere 3.5 watts per side, the Paramour tube amps can play louder and smoother than the Pioneer amp, although the SS amp has greater power.

Third, BC's entry-level kits can play LOUD on super efficient horns. At 12:00 on the dial, I recorded fast SPL peaks in the mid 90s. Nor do the SET amps merely seduce politely. Indeed the incredible voice of Delores O’Riordan, lead singer of the Cranberries, appeared as if her stage amps were suddenly in the room.

Fourth, older AAD recorded CDs sound better with the quaint little pair - they sound easier to listen to. Not great, but good. Newer DDD recorded CDs and SACDs, including the delectable DMP recordings, sound great, of course, sometimes even magically wonderful.

Fifth, I could dial Paul Simon’s lush tropical "Rhythm of the Saints" CD up to 3:00 on the dial with out any apparent distortion. This is something I dare not attempt with the black SS Pioneer warship, even when floating the afternoon away on the pool outside. With approximately 112 dB on average, the 3:00 setting is not just loud; it is painful and damaging to nearby ears. Yet the Paramours can pump out the volume and handle the details.

Sixth, many of my ‘tweaks’ made subtle sonic differences with the SS amp, and I confess to being a tweaking audiophile. A little adjustment, or small improvement, here and there can yield economical and quite satisfying results with super efficient horns. Although crucial at the time, the tweaks hardly seem worth the trouble now. The differences the tweaks made are minute by comparison with the “rightness” of the Paramours.

The CD disc mat, for example, was a purist necessity at 11:00 on the crank it out dial. It adds quietness to some CDs. However, with the Paramours, such refinery is unnecessary.

Adding a single tweak is but a carnation in a bouquet of roses. Yes, one more flower does add to the bouquet, but it hardly does justice to the petal explosion of color. Nor does using the disc mat become the one required accent flower that makes the brilliant bouquet complete. It simply is not needed.

Seventh, my own paramour liked the attention grabbing amps better. “Little miss sensitive ears” quickly said they should stay. “Well, it is like a cool morning at the lake, she said, you can hear the frogs and birds, but the mist holds the sound in. Now, the mist is lifted.”

Do I wax poetic? I certainly hope so. Because in the dearth of any retail stereo shop in Minnesota, New Hampshire, or Florida that sells flea powered tube amps with big old horns, this is the only forum to champion that magical solution. In fact, if it were not for the Doc Bottlehead and Klipsch bulletin boards and the knowledgeable posters upon them, I never would have researched the marriage of 2A3 amps and horns.

Horn speakers, I found out, are amazingly efficient. They idle along with a fraction of a watt at normal listening levels. Only 1 to 4 watts will ring your ears like Chinese gongs and shake cabinets like earthquakes.

SE Tube amps, I found out, have a soft clipping characteristic to create a sound that is … well, umm … even desirable when distorted. Tube amplifiers make the type of harmonic distortion that we subconsciously identify with musical instruments, so that reproduced music sounds always listenable. For a front row seat of the persisting ‘tubes versus transistors’ debate, see the lesson our own John E. Johnson gives in our primer. 

Seemingly under-powered, the rated output for the antique style amplifiers is a mere 3.5 watts and this is at the THD level of 5% (gasp!), going into 1 kHz. While this sort of spec would make transistorphiles shudder, it is typical of SE Tubes.

One of the secrets of high fidelity is that coupling tube amplifiers to super efficient (95 dB/w/m or more) speakers is one of the classic amp & speaker combinations. They form a musical union hard to describe, like soft and flaky piecrust, rather than moist and crumbly. A texture that is clearly a matter of taste. It is a joint effort that makes music. An effort that just sounds wonderful.

However, the Lilliputian output of 2A3 tubes is not suited to normal speakers of 84 - 90 dB/w/m efficiency. To reach high volumes with musical authority, stronger amps with tubes like the 300B for example (of which there is a blossoming crop) should adequately power speakers rated at 90 dB  - 95 dB. Modestly sensitive speakers are best matched with more powerful tube amps as mates, especially for the louder music, larger rooms and more demanding bass. Used or new EL-84 tube amps, for example, can deliver 5 to 25 watts for a little higher price than the diminutive Paramours can.

With super-efficient speakers, even flea powered tube amps have a capacity to sparkle, startle, and surprise at normal volumes. No brushed silver concrete Krell block and B&W 801 solution that I ever heard could do that. Yet, a slack pluck of a bass string, or sharp snap of a snare with the Paramour bottles jolts me out of my pleasant revelry.

Hey, I think to myself, I have never heard that instrument or note before. Yet in fact, I have – it just never came across so delicate or deliberate, so quick or so thrilling. It never came across that way before.

Hey, I think to myself, those chimes never sparkled like that before. When in fact, they have – only I was never impressed. Or, a bass note on a mellow jazz disc would surprise me with a SPUD attack to my gut.

Hey, I think to myself, I have heard that before, it just never shot me such a blow.

The Details

It is all about “the details”. Followers of the tube sound wax poetic over the lush midrange, the sharp treble, and the delicate contrasts of the details.

What they mean is that sensual vocalists, like Grammy award winner Diana Krall, with her jazz covers, or Sarah McLachlin, with her equally powerful smooth rock renditions, are more arousing with the proper amount of tube power. In passages that astound with smoothness and control, their voices are suave . . . their vocal discipline apparent. Properly matched with the right speaker, even flea powered Paramours pull away from the amplifier pack, like a Porsche in the fast lane.

What they mean by “the details” is when an audio engineer puts a bell tinkle or a stick tap, off to the side, the Paramours catch it. They present it up front and off to the side of the soundstage, not buried underneath another note or lost behind another instrument. Supporting instruments play alongside the singer on the holographic stage, not behind or in the back. Now stick taps and bell tingles delight the ears as part of the music when they were barely noticeable before.

Even average recordings reveal aspects about the performance. Diana, for example, sucking in her breath during a quiet passage, or parting her lips. The breath is there with the SS amp. Yet, it is not part of the split-second precious delicacy of the pause – the magical pause that makes you hold your breath alone in the dark for fear of disturbing the artist while she is working. The pause, the breath, they are not part of the artist’s performance with the SS amp. They are merely sounds faithfully recorded and faithfully reproduced.

What they mean is that these odd ball looking amps need help in the lowest octave with today’s bass heavy music and movies, so a subwoofer is required to free them from the task of pushing the large bass waves. But even when 700 watt subwoofers aid the Paramours below 100 Hz, the bass has a quicker, more textured “twang” to it. You hear the string click on the frets more often; you sense the note more frequently. The Paramours are adding the edges to the deep bass, rather than adding the deep bass itself.

The ideal spelling of a bass note might be something like “twaang” – fast, but able to sustain the note, like holding your foot down on the piano pedal in the middle and suddenly releasing it. Comparing my new bargain basement tube amps, or the SS Pioneer, to top of the line behemoth Krell SS amps with state of the art B&W 802s, the differences are particularly noticeable. Especially when listening to the upper bass notes from about 100 to about 250 Hz. Here’s how their sound compares:

Krell and B&Ws: The solid-as-marble B&W 802s give the note a substantially full “ttwwaanngg”. Although slower on the attack, the curvaceous speakers empathize the three-dimensional shape of bass notes so well that they make audiophiles drool.

Pioneer M-22: Aided by 4” square power transformers, my SS reference amp plays the same note as a firm “ttwaang”. See the difference in spelling? The Pioneer is slow on the uptake, able to sustain the middle, but it gives out on the decay side of the note. It never startled with tantalizing midrange or high-end notes – the music was just there. It is accurate, too (such wonderful specs!) Still, the music is just merely “there”. Faithful, perhaps, but just there.

PBC Paramours: The Paramours sing through the note quickly, “twang”. They attack like a Blitzkrieg on notes, so fast that the army is already at camp before the surprise is over. They play the middle part quickly and fade away quickly too, like an army sneaking out at night. They startle with the quick string pluck and then swiftly retreat.

Even traditional reviewers of radiator cone speakers will describe the ‘emotion’ of dynamic horn systems. What they mean is that the realism is so involving that you listen to them again and again. Therefore, Paramours are an emotional sound. Involving, delicate, detailed, and polite.

Second, what they are

BC Paramour kits do not cost as much as Porsche, or even a set of Porsche wheels. 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, but the lowest cost 2A3 amp that I know of . . . period.

The Paramours look like a do-it-yourselfers (DIY) kit. The amps are new products from BC to replace their single ended experimenter’s kit. Mine are one of the first assembled Paramours sold by BC. The amps came in light tan Alderwood enclosures the size of tissue boxes. All of the Doc Bottlehead models share the same top plate. This is the chassis for mounting the hardware of the various kits, in the same way auto manufacturers use the same frames for various models. All of the tubes, transformers, and connections stick out of the top plate. Therefore, the various BC kits resemble each other. There is no protective cage to dissuade prying youngsters from the enticing blue luminescence of the softly glowing tubes.

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.

For anyone who does know “which end is which” on the soldering iron, the wiring and components are easy to modify.

The manual is brief and to the point, yet it appears complete. My amps arrived with large color photos of the underside. Upgrade parts and information are readily available by telephone or by e-mail. Request for assistance at BC was quick, friendly, and informative. Specifically, Wesley Carter answered all my questions fully and in detail. For East Coast customers, their Washington site is three hours behind, so their early evening service is a definite plus. The Doc Bottlehead forum is excellent, with many active and knowledgeable posters upon it. BC shipped the amps snuggled in a bed of styrofoam that was poured into a mold around them. Very smart. (I kept the boxes of course).

The monoblocks certainly do not look like any of my other sleek black boxes on the equipment rack. The binding posts stick out of the top in one corner, and the power switch is 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 side. Not one side or the other looks like the front or the back.

The amps are puny compared to their task. They resemble a turn of the century steam engine jury-rigged 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 from 25 Hz to 37 kHz ± 3 dB.

The antediluvian Paramours use a single 12AT7 tube as the drivers. The driver tubes couple to the 5” high Valve Art 2A3 bottles. The 2A3 tubes (one per mono block) 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. BC says the para-feed output gives the amp a remarkable sense of realism, bandwidth, and bass articulation, particularly considering the price. It also means that a smaller (2 1/2”) 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 speakers.

Because of my success in my selection, if I had to do it all over again – buy tube amps without listening to them first – I would step up to the BC Paraglow kit at almost thrice the price. One thing I will never consider is a high-powered solid-state amp in the same price range as a match for super efficient horns.


- Colin Flood - 

© Copyright 2001 Secrets of Home Theater & High Fidelity
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