AOM Logo July 2000

The Assemblage SET-300B single-ended triode amplifier
(Signature Edition)

Anthony Kershaw

Every time I visit the Sonic Frontiers (SF) factory to pick up or drop off, I notice Vice President Chris Jensen's Volvo parked out front with the license plate "TOOBS". There is no doubt that Jensen and his cohorts at SF are aficionados of glowing glass. Their company was built upon delivering excellence through the vacuum tube. The lineage of that quest for excellence is well documented in As such, it was with great pleasure and much anticipation that I took delivery of the Assemblage SET-300B Amplifier produced by SF's subsidiary, The Parts Connection.

Assemblage SET 300B single-ended amplifier

The single-ended triode sound has been either heaven or hype for most audiophiles since examples of the design started to come down to real-world prices and offer some sort of real-world reliability. The quiet background, reliability, and the intensely musical sound offered by only the best (and very expensive) of these amplifiers have kept the single-ended amp out of many audiophile setups. Kits have been a boon to some manufacturers, keeping the price down and instilling a sense of pride and connection with the piece. SF has jumped into the kit fray with their Assemblage line of power amps, pre amps and digital sources, and by all accounts has been very successful with them. Even so, it took a real leap of faith from the SF design and marketing team to produce an single-ended amp that would compete with some of the best at what in reality is an entry level high-end price.

As my weapon of choice is the baton or flute rather than the soldering iron, I wimped out and asked Johnson for an assembled Assemblage (a US$200.00 factory option for you other wimps). Glenn Dolick, a charming, self-effacing man, and leader of the SET-300B design team, built it for me with the "Signature Parts Upgrade" (US$299.00 on top of the US$799.00 for the basic kit). The upgrade includes Black Gate and Multi capacitors, Caddock and Vishay resistors, Kimber RCAs and Cardas binding posts. During a brief discussion, Dolick stressed the team approach philosophy that has helped The Parts Connection's Assemblage line become so popular. For the budding junior builders out there, he mentioned that the kit, while challenging, is quite straightforward with care and some practice with a soldering iron. Tube complement for the SET-300B is 2-6BX7GT, 1-6SN7GT (Sovteks) and 2-GZ37 (Mullards are supplied). The critical 300Bs are chosen by the customer and are an additional cost. Dolick chose the Sovtek 300Bs for the review sample. All auditioning for this review was with the "Signature" version. Commentary begins after the prerequisite hundred-hour break in period.

The SET-300B was hooked up with van den Hul cable to an Audio Research SP9, with digital sources including the Sony SCD-1 SACD player, Cary's CD-303 CD player (review forthcoming) and the Arcam Alpha 6 CD player. Some comparisons were made with the transistors of the Jeff Rowland Concentra integrated amplifier (review forthcoming). From the 4 Ohm output tap (8 and 16 Ohm taps are available also) I hooked up my reference Gallo Nucleus Solo loudspeakers. The Gallos are 90dB efficient and worked very well with the Assemblage. Anything less efficient would be tempting the clipping demons if playing music at anything near realistic levels. Stating the obvious to seasoned audiophiles, the higher quality the associated components, the sweeter the SET-300B sang.

Having only brief listening experiences with this most elusive of amplification design, the sound of the single-ended triode did for me what it had done so before with examples from Cary and Bel Canto. The intimacy and beauty of sound that many have commented was there, setting my ears tingling at both the delicacy and surprising depth of sonority it produced. It was surprising as the amplifier produces only eight watts (per channel) from its 300B output stage(s). The zero negative feedback augmented (as usual) nothing to the dead-quiet background, with the custom-designed output transformers, open design, black powder coated finish and black anodized front plate adding touches of class to an already classy product.

Not wanting to tempt the power gods, I decided to begin in earnest with some less histrionic musical examples. I sampled some of the newest releases from the Naxos Early Music CDs. They sounded wonderful. The soundstage was as deep and wide as the musical and playback sources would allow - the placement of the various members of Ensemble Unicorn (a fabulous bunch of musicians) stayed put within lovely soundstages on several CDs. The Black Madonna (Naxos 8.553433) highlights songs from nearly six hundred years ago. The inventiveness of the text and music and the brilliance of the performances beamed delightfully through the gentle touch of the SET-300B. And On the Way to Bethlehem (Naxos 8.553132) was equally fine. The low drum sounding the marching beat of the heavy-laden pilgrims marching towards Bethlehem sounding as penitent as the engineers heard. Do not let the pre-medieval moniker scare you away from these great CDs.

I have known audiophiles purchase their single-ended triodes for the specific purpose of playing vocals and chamber music, emphasizing always the intimacy and immediacy of the emotion. On the last two counts, they are absolutely correct. When playing this type of music through the Cary CD-303, the richness of vocals and the essence of the artist's musical expression came through in spades. The same recordings were more two-dimensional through the much older (and cheaper) Arcam Alpha 6 and remained so when powered by the wondrous Rowland Concentra integrated amplifier.

When playing large-scale orchestral recordings, I was not prepared for the wallop the amp could pack. True, it could not handle the Naxos (8.550737) Vaughan-Williams Sinfonia antartica (Bournemouth Symphony Orchestra/Kees Bakels); the low bass on this budget CD is exceptional in its clarity and power, demanding feats of virtuosity from your amplifier if you wish to experience it in real world terms. The amplifier cried the blues on the first organ entry, yet the crying was gentle. But other than a few audiophile woofer smashers, the SET-300B handled most large-scale orchestral works with aplomb. I remember being wowed on several occasions, one of which being the bass drum and tuba in the Landler movement of Mahler's Ninth Symphony (Telarc 80426/Cincinnati Symphony/Jesus Lopez Cobos). I remember the separation of the bass drum timbre and growl of the excellent tubist combining in a correct layer to give the feeling of power that many audiophiles desire.

Headbangers and ravers should avoid this amplifier, for they will not find Nirvana here. The eight watts and delicate demeanor simply cannot do justice to stadium music of any type. Intimate vocals and pumped up blues were no problem, though (I remember a local distributor listening to the demanding opening track of Doug MacLeod's You Can't Take My Blues - JVCXR-0027-2 - and shaking his head at the quality of the playback, especially the depth of the bass). Sound from jazz standards by Miles and Coltrane reminded me of the intimacy of the event, their playing abilities blissfully unaware of the limitations of technique or musicality. So it went from recording to recording, the much-lauded single-ended magic wending its way through the notes into the listener's soul, a sound that I quickly realized can reach places that only the greatest transistors find.

The supplied Sovtek and Mullard tubes did a fine job, and let me hear what the single-ended fuss was about. One of the Sovtek 300Bs shut down quite prematurely, with SF offering the wonderful (and equally inexpensive) Valve Art 300Bs as replacements. These tubes were much less earthbound when it came to timbral accuracy and relaying the most delicate information, and were possibly just a little sweeter than the slightly rough-hewn Sovteks. I did not swap tubes other than the 300Bs - I am sure that many prospective buyers will have much fun swapping all the tubes. Except for the badly behaved Sovtek, the tubes have been glowing for some six months now with no problem. Like most well cared for tubes, these should last three to five years.

My lengthy audition period with the SET-300B was very pleasurable, and made integration with various pieces of equipment easy and effort-free. Its sound adapted well with all types of music with the exception of the most demanding source material and will offer the single-ended faithful a fine alternative and those new to the glories of this design a reliable and inexpensive way into the fold. Highly recommended.

All Assemblage kits come with a satisfaction and assembly guarantee, a two-year limited warranty against manufacturer's defects, toll free phone support (in the U.S. and Canada only), and a comprehensive construction manual with step-by-step instructions, pictures and illustrations.

Assemblage SET-300B Amplifier
Manufactured by The Parts Connection (a divison of Sonic Frontiers. Inc.)
2790 Brighton Rd., Oakville, Ontario, Canada, L6H 5T4
Toll Free: 1-800-769-0747 (US & Canada only)
Phone: 905-829-5858 Fax: 905-829-5388
e-mail:, web:
Price: US$1298 (Basic Amplifier - Assembled $999 ($799 Kit + $200 Assembly cost), - Signature Parts Upgrade $299)
Source of review sample: Manufacturer Loan

Manufacturer's Response

Dear Anthony,

Thank you very much for the chance to respond to your wonderful review on The Parts Connection's new ASSEMBLAGE SET-300B Power Amp.

In particular, we would like to express our thanks for all the attention to detail you showed while reviewing the SET-300B…the intimacy shown to the nuances of the design were readily apparent throughout your review. It is greatly appreciated as well that the auditioning was performed by someone who is a SET (single-ended triode) 300B enthusiast, one who has the correct frame of reference and perspective for the boundaries of such designs, and thus, can truly appreciate our product for what it is.

Well, it seems to us that you have said it all, already in the review. As duly noted, this project is continuing to prove to be a great success, as it appears that the goals set out by the design team have been met in all respects - including the ease to which the kit builder may 'play' with the circuit components to roll his/her own flavour; the provision to add an attenuator for direct connection to one's favorite source; the inclusion of a mute switch (borrowed from the SFI Power Amp series) allows this amp to be very friendly towards experimenting with interconnect cables; and the ability of the amp to be wired as a Mono block amp to double the output power. Along with the design's intoxicating sonic attributes, these features are all very enticing. Moreover, lets not forget to mention that tube equipment is so much fun to own - just trying different tubes, in and of itself, is a very satisfy exercise in adjusting the sonic character of the amp to one's own taste.

Once again, thank you for the positive recognition of the work invested into this SET-300B design - we spent literally two years bringing it to market - the result being something which is "definitely" not an over-priced "me too" effort!

TPC looks forward to submitting future 'fruits of our labour' ASSEMBLAGE products to you and your staff, for both your enjoyment and scrutiny.

Glenn Dolick TPC/ASSEMBLAGE Product Designer
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