The PM845 power amps gave slightly mixed results, and are attributable to the issues I alluded to when comparing the 845 and 300B. To this day, I haven’t heard an 845 or 211 amp that could match the sound of the best 300B amps. The only thing really going for the 845 is the extra power. In my system, with the speakers being used, in my large room, and playing material that requires balls, the extra power of the PM845 amps were welcome.
What I heard in the distortion was similar to other amps of similar design, which is a small grouping. The 845 isn’t as pure as the 2A3 or 6SN7 used as input and driver tubes, and can’t compete against the 300B. The amount and type of distortion is more audible with the 845, though not objectionable if driven correctly. With the PM845, the 2A3 driver tube and driver transformer mean that the level of distortion before the 845 output stage is much lower than many designs using the 845. The “flavor” of the amp was slightly amber or tan, with a touch of opacity. It reminded me of Chimay Rouge Ale. In contrast, my favorite 300B amps, when not being overtaxed, have a flavor that is closer to good champagne.
The PM845’s dynamics were quite good, though again, the macro-dynamics were clearly superior to the micro-dynamics. The use of multiple transformers and multiple stages smoothed over microdynamics and minute details, something that is going to be system dependent. With the combination of Pure Black 101 preamp, my system took on a very laid back character: very easy going, doing a good job of large scale music, but also glossing over details. When used with a tweaky moving coil cartridge, horn loudspeakers, and the correct cables and tubes, this weakness could be ameliorated somewhat.
The only real weakness of the amp comes back to the consequence of using transformers and multiple stages: limited bandwidth. It’s funny, but had I paired this amp with more traditional speakers, and most horns, the bandwidth issue might not have been audible. Because of “poles and zeroes”–look it up if you want to know more–there was some audible phase shift and roll-off in the top and bottom octaves. I want to reiterate: Had I not been using the GR Research speakers, I might not have noticed or my perception would have been less acute. When swapping from the PM845 to a entry-level transistor amp from Parasound, the transistor amp clearly had another octave of extension, along with less distortion in the low bass and no audible phase shift. Admittedly, I preferred the PM845 for listening to music, but I feel compelled to reveal all. Part of the issue is the design. All amps with multiple transformers are going to suffer from phase and roll-off issues, though the quality of transformers can greatly affect the phase and frequency issues. The other part is the quality of the transformers. I don’t know if these transformers are using top notch laminations, or not. What I can infer, because I have heard the Audio Note amps, is that the transformers in the Melody products are not on the same level as Audio Note. No, not a surprise, and it shouldn’t be. There’s a reason the Audio Note products are so expensive.
So, do I like the PM845 amps? Yes, I do. They have a definite character, and the way they deal with powerful music is very enjoyable. Most recordings are far from audiophile grade. The slight opacity and amber quality of the PM845s made many recordings sound sweeter than a clinically pure transistor design. Also, the majority of my recordings did not reveal the frequency limitations of the PM845. One of my favorite CDs is the Chicago Symphony, Bernstein recording of Shostakovich’s Leningrad symphony. The fourth movement is a monument to loudness. When the key signature finally switches from minor to the relative major, it’s a musical “*&^%$#@!” to the Nazis, then bombarding Leningrad, a bombardment that would go on for 900 days, and which was still ongoing when the symphony was completed. With the Melody Valve preamp and amps, and the enormous GR Research LS9s, I felt like I was manning a howitzer on the front line. With most versions of my system, the finale was a let-down. I heard more limitations than music. The Melody Valve gear realized the power and fury of a sincerely pissed-off Dmitri Shostakovich, the flamboyance of Bernstein, and the Mack-Truck-in-a-tunnel sound of the Chicago Symphony brass. Want to know why the Russians won? Listen to the 4th movement, and you will understand. Sure, it’s more complicated than face value, but you will understand. Many critics panned it, but most critics never lived the hell that most Russians were living.
Like I said in the introduction, most powerful single-ended amps that use these high impedance triodes sound mediocre. Some even sound beyond mediocre. By circuit design, and choices of materials, the PM845 is a good sounding, powerful, single-ended amp.
One unsolved oddity I need to mention was a loud 60 Hz “hum” when connecting the preamp’s balanced outputs to the balanced inputs of the power amps. I tried a couple different interconnects, but that wasn’t the problem. I suspect someone wired up either the preamp outputs or power amp inputs incorrectly. If it was a ground loop, it was the loudest ground loop in history, so I think it was something incorrectly wired. Because the sound using the “out/low” was good, that is what I stuck with.
Also, the preamp has too much gain. When using the “out/high”, the amount of gain made the volume control almost useless. While using the “out/low”, I still had a somewhat limited use of the volume control, with most listening done at or below the 11 o’clock position. Perhaps either the preamp or power amp could have one stage of amplification removed? If so, the sound would only improve. However, there will be some people with inefficient speakers who appreciate the extra gain.
Both pieces, preamp and power amps, had a little hum. Due to the numerous and large size of the transformers being used, it could have been coupling from transformer into another part of the circuit, or another transformer, or even the interconnects. I have heard the same issue with equipment of similar build. On the other hand, the noise level was low enough that I did not hear it, unless I was trying to hear it. Understand? I had to turn the gain up and put my ears near the speakers to hear the noise, something that did not interfere with my enjoyment of music.
Final thoughts
I’m a slow reviewer, but this one took even longer than usual. The sound was very good, but had a few flaws. What took so long was to figure out the flaws. Though happy with the sound, I knew there were a few weaknesses compared to more perfect, more expensive designs. Unlike most of the equipment I have heard, these pieces had the audio equivalent of good poker faces. They are good enough to cover up their own shortcomings, which is the sign of a good designer. Had I less revealing speakers, there’s a chance I would not have heard most of the shortcomings. Most horns, which have problems with roll-off and resonance, would be much more colored than these electronics, swamping the limitations of the Melody gear and playing to their strengths. It’s odd that the importer accidentally paired these electronics with speakers that easily reveal the differences between capacitors, circuits, transformer core materials, digital vs. analog, and so-on.
A bone of contention is the use of the 101D triode, a directly heated tube some 90 years old in design, if not older. The ancient design doesn’t bother me. What does bother me is not using the 101D in the power amp. You have a directly heated 2A3 driving a directly heated 845? You mix 101D and 6s7 in the preamp. But the power amp uses the 6sn7 as the input tube, and doesn’t feature a 101D. Why? Why not only use the 101D if you use them at all? Why not use the 101D in place of the 6sn7? But, it’s not a big bone of contention. The 6sn7 is a better choice than the shabby sounding 6h30p “super tube,” or any of the mediocre sounding 12au7 variants. I have been told that the 101D’s in the preamp are used in the power supply. I did not inspect the internal guts of the preamp to determine what function they serve. I like the idea of picking a technology and making the most of it. Why not go to an entirely directly-heated circuit? It’s a small criticism, but also an encouragement to the designers at Melody. Pick a road less traveled, and further establish a unique identity!
Of the pairing, the preamp really does establish itself as a more universally recommended component. Regardless of speakers, room size or ideological bent, the preamp is a good sound product that will find more homes than the big power amps. I do miss its absence, partially for the sound, and partially for the looks. It’s a winner.
The value here is very good. Overall, the sound is very pleasing, though it is warm and forgiving more often than not. They stack up well against more expensive gear. I wasn’t expecting them to sound as fabulous as Audio Note. But, because they do attain a healthy portion of Audio Note goodness, along with fantastic looks, at a relatively affordable price, they are players in a small market. The preamp is a good choice for many listeners, while the power amps are appropriate for those of you with moderately efficient speakers that want SEDHT sound. Melody Valve has made tasteful choices in assembling products of good sound, good value and good cosmetics. It’s an uncommon combination that makes them an easy recommendation.
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