World Premiere Review!
I have something to admit. I am a music lover. No, it's worse than that, I'm a certifiable music junkie. I listen to music at home. I listen to music at work. I listen to it in the car. I even hear music in my head when no music is playing. I'm always looking for new music to feed my addiction. My wife complains that my Christmas list is boring because all I ask for is music.
Well, I do throw in a request for a pair of Berning 845 Monoblocks, but that never happens. Oh yes, my wife is a music junkie, also. She's always on the prowl for new music to add to her collection. Our tradition on Saturday and Sunday mornings is to listen to an album all the way through while eating our breakfast. It may be something brand new, or an album we haven't listened to in a long time. Usually, after our meal, we'll share what we think about it. Yes, music runs through our veins.
With new precautions, my Dad and I have been going to the symphony again. The last concert we attended featured Beethoven's 9th Symphony. I've listened to this piece many times, at home, so I thought I knew what to expect. I was completely wrong. Being there, in a packed concert hall with the orchestra and massive choir in front of us, took me to a new level. How does this happen? We're up on the balcony, but the excitement is undeniable. It's almost like a magic trick to be surprised by a piece of music we know so well. This is what we music lovers live for, that discovery of new musical adventures and the re-discovery of old ones.
Of course, that seeking of new thrills is what drives us audiophiles to try out new equipment, so we can better connect with favorites and make new musical acquaintances along the way. For quite some time I've been wanting to try out an SET 300B amplifier in my home. I've heard some on the showroom floor, it's just not the same as having it in your living room, listening to your music with your dog cuddling up next to you.
Ah yes, the 300B triode. I'm sure all of us who went to a movie theater before 1980 listened to 300Bs doing their thing, we just didn't know it. Now they are one of the preferred tubes of the SET crowd. There are many ways to make the 300B sing, and Aric Kimball has taken his own approach. First of all, the Custom 300B PSET is a two-chassis design with a separate power supply and amplification units. Not only does this inhibit stray noise from the power supply entering the signal path, but it also makes it a heck of a lot easier to manhandle into place than a single massive box. The power supply utilizes a large 1 amp toroidal power transformer that provides plenty of current for the amp in quad mode.
The rectifiers are two 6CG3 damper diodes that are quieter than regular tube rectifiers and can handle the extra current. The power supply is connected to the amplification unit via two Speakon connections, which I have to say, are the most intense power connectors I've seen in a home-use amplifier. The amplifier section of the Custom 300B PSET starts with 6SN7 input tubes in SRPP mode. Those are coupled using Audyn True Copper foil coupling capacitors to triode-strapped 6V6 driver tubes. The drivers are then coupled to the 300Bs using custom-made interstage transformers. This is where it gets really interesting and makes the Custom 300B PSET so unique.
You then have the choice of running the amp in either SET mode with one pair of 300Bs or PSET mode with four 300Bs. As you can imagine, in PSET mode you have twice the power. Plus those four 300Bs in quad formation look so cool. There are a lot more great features in this amp that I won't go into detail about here. I must add, this is a beautiful amplifier. Both bases are constructed of alternating light and dark woods, and cool retro ammeters on the front of the amplifier unit.
Before I start describing the sound of the Custom 300B PSET, I need to discuss the speakers I paired with them. I had been searching for a while to find a pair of speakers that would work well with lower-powered amplifiers and work well in my living room. After an exhaustive search and advice from an experienced DIY friend, I decided to build my own. The Markaudio Alpair 12P full-range drivers were the starting point. They are rated at 92dB/W/m for efficiency, have a remarkably flat frequency response, and have a very forgiving impedance curve.
Finally, the Markaudios are reasonably priced. I decided the to use the Super Pensil 12.2p design, which is a tuned-port enclosure designed to work with the Alpair 12P. I built them in the summer of 2020 and have been using them exclusively since then. After about a year, they seemed to be completely broken in. I know not everyone is a big fan of full-range-driver speakers, but they work well in my living-room setting. If you like to listen to head-banging music at 100 dB, these are not the speakers for you. If, however, you prefer to listen to complex music at reasonable volume levels, they are highly recommended.
The first thing I noticed about the Custom 300B PSET amplifier is how dead quiet it is. Not just quiet with no music playing and the volume turned up. It's quiet in the way background instruments are better delineated and more fully realized. Sometimes, this can be quite startling. Mahler's Das Lied Von Der Erde [Columbia Masterworks MS 6190] will certainly utilize the full force of the symphony orchestra, but he also took the opportunity to strip things down for maximum impact.
In the final movement "Der Abschied", the horns play a supporting role to the strings and woodwinds. With the Custom 300B PSET amplifier, I was, for the first time, really able to appreciate Mahler's close harmonies between the trumpets, trombones, and french horns, generating rich overtones. This quietness also lets the subtleties of the musicians playing come through. The deep bowing and generous vibrato of the strings, during the last movement, drip with pathos and the lip trills on the french horns add menace to their "fate" motif.
Sure, I was able to hear those things before, but the Custom 300B PSET allowed me to feel them more.
One of the hallmarks of good SET amplifiers is their ability to correctly reproduce tonal textures. Like I've said, I've yearned to have a 300B amplifier in my home for quite some time. That fire was first lit when I started reading Sound Practices and Listener. Over twenty years ago, Harvey "Gizmo" Rosenberg wrote an article for Listener titled "King Tone's Ascension". One line from that article has stuck with me since I first read it so long ago: "If you have the widest stereo image, have woodifying micro-dynamics, and whopper size bass…none of this matters, if you don't have natural tone." The Custom 300B PSET amplifier always let the instrument's natural tone shine through. In the last movement of Stravinsky's, criminally-underrated, "Symphony in C" [EMI Classics 50999 2 07630 0 8], he opens with the bassoons, intermittently, joined by the trombones and coronets.
All of the instruments are warm, rich, and full with no edge or harsh overtones. They are then joined by the violas and cellos. For me, string sound is always the toughest one to get right. Yet, the Custom 300B PSET amp in my system got me closer to the real thing than I ever have, in my living room.
"But wait!", you say, "If I don't listen to classical music, will I be able to enjoy the benefits of this amp?" Of course, you can. Listening to Radiohead's OK Computer on vinyl [XL Recordings XLLP781] was a treasure trove of musical treats. The varied and creative use of reverb and echo on Thom Yorke's vocals, kept me guessing as to what was coming next. On many of the songs, Jonny Greenwood's guitar was so pitchy that I got up a couple of times to make sure nothing was wrong with my turntable. The cohesiveness and beauty of "Let Down" was a gut punch. The piano on "Karma Police", and other songs, sounds like an old upright. Finally, the startlingly clear and straightforward production of "No Surprises" is a surprising change of pace.
Now that I had a good handle on the sound of the amplifier in SET mode, it was time to switch over to PSET. I put in the four Psvane 300Bs and flipped the switches forward. After a good break-in, what did I hear? The additional power did make the deep bass more authoritative. The opening of "Also Sprach Zarathustra" [Mobile Fidelity Sound Lab MFSL 1-522] is a test for any system, yet the Custom 300B PSET had no trouble reproducing the opening notes. On Who's Next, power came with a tradeoff. I did notice a slight reduction in the inner detail that I heard with the amplifier in SET mode. I talked to Aric about this and he said that it was what he expected. He also told me the Psvanes I was using were not a matched quad. If they were, the sound would be closer to the single pair. Of course, Aric will provide a matched quad with the amplifier..
Whether the Custom 300B PSET amplifier was in SET or PSET mode, one of the features I enjoyed was the sense of aural space it rendered. The LSO's rendition of "Carmina Burana" [Mobile Fidelity Sound Lab MFSL 1-506] was recorded in Royal Kingsway Hall instead of a recording studio. You can clearly hear that with this amplifier. The spacing of each instrument was clear and one could sense the air between them. In addition, the soundstage lets you hear the size of the hall.
I thoroughly enjoyed my time with the Custom 300B PSET, but that day came when I would have to say goodbye. As a treat for my birthday, I decided to sit down for one more extended listening session before I packed it up. I started with ELP's Brain Salad Surgery [SD 19124]. That was a mistake. I always wonder if Eddie Offord ran his mixes through a bag of broken glass. But it did demonstrate how faithful the Custom 300B amplifier is at reproducing what was given to it. To purge me of that unpleasant experience, I put on Bill Evans Trio Waltz For Debby [Analogue Productions APC 009] and listened to both sides all the way through. As I listened to this famous recording of three musicians in perfect sync, all-time melted away. For that short amount of time, I was at the Village Vanguard on the evening of June 25, 1961. Could this recording be that old? With this amplifier, time travel was possible.
Of Sound And Music