Author Topic: In-depth Review of Melody PB101  (Read 1739 times)

Offline Hugh

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In-depth Review of Melody PB101
« on: February 14, 2013, 06:57:47 AM »
Last spring an auction seller posted for sale an Audio Research SP-3B preamp. The legendarily phantom SP-3B was an upgrade offered by Audio Research in 1978, to put most of the advances in design present in the then-new SP-6 into the SP-3, 3a and 3a-1 circuit. I encountered just one in-the-metal in 1979, and have never seen one since. That auction post brought back a strong memory because while the SP-6B I owned in the early 1980s was a pinnacle design at once more objective and broadband than the SP-3a1 I used in the mid-through-late 1970s, the SP-3B not only retained the SP-3ís superior control flexibility but also the 3a-1ís nearly best-ever midrange tone density. It reminded me how few truly musically-convincing preamps the high-end audio market has given us, and how many mediocre Ė or worse Ė units have been foisted on us at every price level.

I am writing here about the Melody Pure Black 101, that joins the very short list of musically-convincing line-level preamps available today. If youíve never seen Melody audio gear, but you know itís built in China, be ready to encounter build quality that is globally competitive, not just at the top rank of what is sometimes called ďChi-fi.Ē Chinese, Taiwanese, Korean, Thai and other Asian audio producers are giving us dramatically-expanded choices in hi-fi, from cheap & cheerful to category-killers priced in three or four figures instead of five or six. The rush of hi-fi coming out of China and other parts of Asian is reminiscent of the entrepreneurial burst here in the US post-war and again in the 1970s / early 1980s, particularly since many of these Asian hi-fi products are coming from a culture that reveres education and music, and from a high incidence of designers who are musicians or who include musicians in their design processes. And then there are the small shops that simply build what they think sounds good to them. As good as Melodyís better Chinese competitors are, Melody build quality is peer to anything coming from anywhere. Across the board in their line, Iíll say I have seen and heard enough of it to see that design and execution of their electronics are uniformly sensible and excellent.

The Melody Pure Black 101 preamp is a 6sn7-based design that uses tube rectification, and tube voltage regulation. Its list price is $4499 in the US. It is the most current update to the Melody SHW1688 preamp produced for several years during the 2000s. Itís sleek, dipped-in-limousine-lacquer-black gloss finish is distinctive enough, but the steampunk accent provided by the birth-of-electronics-era globe envelope dual 101D tubes that provide voltage regulation, suggest you are about to hear something unusual. The PB101 is labeled to accept either 5ar4 or 5u4 family rectifiers, and this predictably turns out to be a tuning option for dialing in system sound. The other striking visual aspect of the PB101 is its physical configuration resembling an integrated tube amplifier. The open chassis preamp does have a removable tube cage, but behind it and the tubes are three large black potted coils that one can easily assume are power transformer and two output transformers just like an amp. Is this a transformer-coupled preamp? No, it turns out the three potted blocks are power transformers and two large chokes, further assisting power regulation. Given that the PB101 weighs about 50 pounds, you can be forgiven thinking itís an amp. But this is a preamp wherein a steel chassis, two large chokes and a large power transformer, along with an interior stuffed full of premium parts including film-in-oil capacitors, quickly amounts to 50 pounds. Switching between the five inputs is manual, but remote control of volume is present, the remote itself embedded in a block of machined aluminum anodized black. Before you ever turn it on, the PB101 looks and feels well worth its price, in terms of material execution.

I have used my Pure Black 101 as the sole preamp in my primary system for the past year. It replaced the excellent Klimo Merlino Gold+ preamp, itself an $8000 unit in todayís market. The change was prompted not by any particular dissatisfaction with the Klimo. The trigger was upgrading to Zu Definition 4 from Definition 2 speakers. The Def2ís slight tonal recession was nicely compensated by the Klimoís 6922/7044/e88cc/CCa small glass forwardness. The Klimo is a punchy preamp having a sonic signature that leans into you with solid bass, top end finesse and bold midrange projection. However, Zuís Definition 4 is built around their new Nano-tech FRD mated to the Radian 850 compression supertweeter and the cabinet is structurally new. The Nano FRD does not have Def2s slight tonal reticence and the cabinet uses more sophisticated methods for resonance control that keep it quiet while not darkening the sound of the full-range drivers as the Def2 cabinet structure did. I was looking for a little more grace, which the speakers could leverage, and knew Iíd likely find it in a 6sn7 preamp. 6sn7 preamp circuits, scarce as they are, have traditionally delivered grace and space, and a sense of effortlessness that is difficult to get from nine-pin small-glass dual triodes like the 12ax7 and 6922. Almost immediately, my top contenders were the Valvet L2 (Soulshine was not yet 6sn7-based; it is now) and Melody P1688 or Pure Black 101.

I was able to arrange an audition of the PB101 in my system for some extended listening so I didnít have to guess whether it would work for me. I had also heard the prior P1688 and P1688-II in my hifi systems a few times over the prior few years, as well as the Valvet. When I first heard the Melody 1688 preamp back in 2006 or 07, I wrote then that it was one of the three best preamps Iíd ever heard, so I had high expectations for the Pure Black 101, which is both an upgrade to and revision of the 1688 circuit.

My unit was new, unopened. Fresh out of the box, when I first fired up the Pure Black 101 I wasnít met with the sound that so impressed me in the P1688. The 101 was OK, but had nothing close to the dynamics of its predecessor, nor its sensational tonality. Dynamics were somewhat pinched. I had guests, and after listening to the PB101 for about an hour, they all demanded to listen through the Klimo again, and I agreed. I knew I had the PB101 for several days ahead of me, so I was committed to giving it every chance to be convincing. The next morning, I put it back in my Definition 4 system and let it burn in. For context, this system has vinyl and digital sources (Zu103, Denon DL305 and Ortofon SPU Synergy phono cartridges and the DAC is mhdt Havana Balanced with capacitor upgrades, AD1865 chipset instead of the stock PCM56P, and Bendix 2c51 output buffer tubes), The Jasmine LP2.0 phono preamp into the Melody pre, and amplification is Audion Black Shadow 845 SET monoblocks. The system is tied together with Zu Varial interconnects and Zu Ibis speaker cables to the Def4s. Hour by hour during the first two days running in the PB101, sound improved but it was not in league with what I remembered from the P1688. However, I also knew that the PB101 had many parts upgrades from the P1688, including oil caps and of course the big magnetic in the power supply. To hasten things along, I decided to change out the stock Chinese tubes. I had multiple NOS rectifiers and vintage NOS 6sn7s in my tube stash so I gathered some alternatives together and began rolling glass.

First up, I experimented with rectifiers. I have lots of experience with modern Chinese and Russian production tube rectifiers in my guitar amps and my Quad II Jubilees, generally not finding them to be dynamic nor tuneful relative to known capabilities of the amps they were put in. There is one exception that Iíll get to in a moment. Removing the stock Shuguang 5ar4 rectifier, I listened first with a 1940s coke-bottle RCA 5u4. The preampís tonality and resolution immediately improved. The 5u4 has a greater voltage drop than the 5ar4 so I expected the RCA 5u4 to sound romantic and relatively soft. It made the preamp seductive and liquid, but bass discipline was lacking. Lots of beauty but I knew I could get more objectivity without sacrificing tone. Next, I listened with a 1950s GE straight-bottle 5u4gb. This rectifier firmed up the bass somewhat, reduced some of the RCAís generous acoustic spatiality, and sharpened the top end just a bit. The Definition 4s have an in-built powered sub-bass module with a down-firing 12Ē driver. If you room can support it and its present in the music, itís capable of flat presence down to 16Hz. So bass quality is essential to avoid distracting bloat. I next listened with a short-bottle Mullard 4-notch 5ar4. Everything fell into place. The voltage drop across the 5ar4 is only about a volt, compared to as much as 25v across a 5u4, so the power supply firmed up the bass, put some snap in the preampís rapidly-improving tonality and kept the top end smooth but more extended, with better detail. Last, I tried the best current production rectifier Iíve heard, the Shuguang-sourced 274B that tubestore.com sells as part of their Preferred series. This rectifier has thick glass and a very hard vacuum, along with better plating and metallurgy than the base Chinese 274B. It is also a hybrid of sorts, having less voltage drop than a vintage 274B, but more than a 5ar4, and its heater current draw is that of the 5ar4 Ė less load on the power transformer than the 274B. This tube also sounded remarkably good with the PB101, as it also does in Quad II-Forty amps and in guitar amps. It brings great snap and articulate bass, with a big and rich soundstage. The Mullard 5ar4 outclasses it for tonality however, so I returned to that.

With the rectifier settled, I turned my attention to the 6sn7 tubes. The basic Shuguang 6sn7 is adequate and reliable but not exceptional. I figured this had to be where I could induce the PB101 to surpass its 1688 predecessors. First was a matched quad of unobtanium WWII NOS Sylvania ďchrome domeĒ metal base 6sn7s. BOOM! Wow! The Melody sprang to life. Dimensioning, tone, human presence, texture and energy blossomed out of the preamp. It was better in all ways than I remembered the P1688 and it was more relaxed and less urgent than the Klimo. Unlike the Klimoís and the Valvetís bursty, explosive energy, the Melody evidenced its dynamics more like juggernaut tidal surges. The swells of music, including a full orchestra, were better represented than Iíve heard from small-glass preamps. I could have left it at that, because THIS was as good as a preamp gets. But I had other tubes to try. Next, a matched quad of 1950s NOS brown base Sylvania chrome dome 6sn7wgt. These returned some of the top end texture and detail that the WWII chrome domes polish off, at the expense of a small recession in midrange tone density. Bass character was closely matched. With 845B triode power tubes driving the speakers, I accepted the tweaked dial-back in tone density. Before settling on the brown base chrome domes, however, I also tried a matched quad of 1970s RCA coin base 6sn7gtb. This tube gave the Melody a modern tilt, with leaner, tighter bass, sharpened top end and transients, and leaner tonality in the midrange but still leaving intact and present the generosity of space and grace expected of a tube preamp. A couple of other premium current-production tubes I think worth trying, based on having heard them in other 6sn7 preamps: the Shuguang Black Treasure CV-181z and the new Sophia 6sn7. The CV-181 (NOT interchangeable with NOS Euro CV-181) has some darkness to its tonal balance, while the Sophia takes some burn-in before its out-of-the-box glare melts away.

For the past year, the long-lasting Sylvania brown base chrome dome 6sn7wgt quad has remained in the Melody, along with the also-death-defying Mullard 5ar4. Occasionally I roll in the Tubestore Preferred 274B when I want more snap with specific music. That leaves the question of the 101D tubes. The stock 101Ds are sourced from Guigang in China, and there is nothing wrong with them. They are quiet, stable and do their job. I tried the Full Music mesh-plate/ceramic base 101D/n and while it is beautiful to see, in this application it was noisy and didnít deliver sonic improvement other than a somewhat large soundstage when music scale warranted. What I did find to be a small but discernible improvement is the Shuguang 101D Ė itself a large-globe, gorgeous tube visually. The Shuguang 101D is even quieter in voltage regulation duty than the Guigang, and it delivers subtle resolution and tonal improvements up and down the full frequency range.

As with most categories of hifi gear, only a small handful of products impress me as worth owning, at any price level. Iíve written elsewhere that most of hifi disappoints me, and I view most designers as misguided, pushing us progressively further away from natural presentation of music performance and forever further into an artificial realm of stripped of organic tone and convincing musical realism. Melodyís designer isnít among them, and the Melody Pure Black 101 isnít one of those components. With judicious upgrades to the stock tubes, this line level preamp is a timeless asset to any component music system, with tone, resolution and dynamic grace that especially fits in any system assembled for holistic presentation of convincing musical realism. Bringing things full circle: with the right tubes in the PB101, that nearly best-ever midrange tone density from the long-ago ARC SP-3B is present and accounted for here.

Some details worth knowing:

1/ Documentation is scant, and very little detailed information is forthcoming from Melody. Pretty much anything outside of specs is unpublished.

1/ The PB101 had five pairs of inputs. One pair is XLR for connection to balanced sources. The preamp is not balanced, according to the US importer, Hugh Nguyen at Angel City Music. But in some cases, like my mhdt Havana Balanced DAC, the single-ended outputs do not have the same voicing as the balanced outputs. So I can use the balanced outputs connections without adaptors to single-ended RCA.

2/ The PB101 had three sets of outputs. Two RCA output pairs are labeled ďhighĒ and ďlowĒ respectively. The difference isnít documented. The preamp gain spec is 20db. There is very little difference in the audible gain behavior from the two different outputs. I am guessing this is an output impedance designation, which may or may not be material to your amplification. I just cannot be sure without further information. The third pair of outputs are marked ďBalancedĒ and are XLR.

3/ Controls are on/off switch (rotary); volume (motorized pot with channel balance specíd at less than 0.5db 20Hz through 100kHz; input selector (rotary). There is a subtle, gold colored power lamp centered under the volume control.

4/ The supplied tube cage is heavy-gauge sheet metal, slotted and lacquered. I donít use it but it is effective if you need it.

Since I bought my Pure Black 101, Melody has released a more expensive model from a more premium ďANĒ series, the P2688 preamp. That preamp is based on the vintage Western Electric 403 small-bottle pentode for signal amplification. It uses a similarly robust choked and regulated power supply, including the 101D globes in voltage regulation duty, and the tube rectification. Itís $7000. I am sure it is very fine and may be better than the PB101. I know it will be quite good based on having heard the AN-211 integrated amp that is also part of that line. I will have to hear it before I know. My skepticism is rooted in some doubt that the pentode circuit can equal or exceed the sonic grace of the 6sn7 triode. Or will it just sound more ďmodern; more hifi?Ē Thatís a question to be settled another time. My Klimo Merlino Gold+ had a run of 7 years in my primary system. This Melody Pure Black 101 is already feeling more settled still inside of a year.

Phil
Hugh Nguyen
Angel City Audio
Exclusive Melody US Distributor