Aum Acoustics 45 Integrated

“This amplifier is the finest sounding amp at any price. It produces the best 2W of power obtainable. It’s only compromise is the fact that you need high sensitivity speakers (around 100db or above) to use it well. Other than that, the transparency and “realness” factor is better than anything I’ve ever built and better than any commercial amp I’ve ever owned or heard.” -- Richard Becker, Aum Acoustics

When I was 10 or 11 years old, as the 70’s slid into the 80’s and the Empire was striking back, my musical tastes changed from the country classics my family listened to on the radio in the car (WMZQ), to the “classic” rock, prog rock and heavy metal that my older cousin Steven liked. Soon Rush, Pink Floyd, Marillion, Led Zeppelin and Black Sabbath dominated my afternoons after school. I played their records over and over again on my little Sanyo record changer with a built in 8 track player and two small satellite speakers. In other words, total electronic crap, but the music was glorious to my ears. Later I received a much more sophisticated Mitsubishi all in one unit, the kind of setup they sold in the electronics section at Woodies, with a dual cassette deck and a linear tracking record player. It was my first “hifi” and I thought it was Boss! Wearing huge Radio Shack headphones, I would lie in a hammock in the dark basement of our house in Falls Church and let The Wall or 2112 just wrap over me. But when I left for school, I left behind that kind of settled lifestyle for a long time, and hifi never really came onto my radar again until 20 years ago.

I’ve always liked quality, and something a little different, and it didn’t take me long to figure out that single ended amps and DIY full range speakers were the direction I wanted to go. Since then I’ve been on a bit of a journey to hear and experience as much of the best that this strange little corner of the hifi world has to offer, looking of course for the feeling of those early moments in the hammock when it was all new to me and was simply amazing. Thanks to streaming and my sporadic but often wonderful vinyl finds at Salvation Army and Goodwill, music has continued to grow in my life, and it seems there is always new territory to discover and new sounds to experience and enjoy. In that vein, the amplifiers I’ve liked best have gotten me closer and closer to the magic of that early experience. Here then is the latest and greatest bit of electronic wizardry to deliver the goods, Richard Becker’s Aum Acoustics 45 Integrated.

This is an amp that I feel the Universe meant for me. I’ve evangelized a number of things on this website, one of them being a set of Tamura made power and output transformers from the 1960’s, found in certain Sony reel to reel recorders. They aren’t a secret, but I’ve certainly been happy to point them out to a wider audience. I’ve had 8 or 10 amplifiers now based around these transformers, the only two amps I’ve ever commissioned used them, and their “sound” is always pleasing to me. Alan Eaton, who makes what I feel is the best sounding 45 amp I’ve heard, also uses these transformers pretty exclusively.

Enter Richard Becker of Aum Acoustics, who built an Elekit 8600S for me, and then purchased one of Alan’s amps after reading about it here. He loved the sound, and the simple circuit, and set about designing and building a full on, no-holds-barred take on Alan’s amplifier, with the beautiful simplicity of Alan’s circuit intact but elevated by the best parts on Earth (expense be damned) and the finest of Alan’s transformers, hand potted by Alan himself. The result is the creation below, a good candidate for the title of ultimate single ended 45 amplifier, and without doubt one of the very best sounding amps I’ve ever experienced.

Parts quality matters. I knew that before, but this amp has really shown me how much they matter. I admit that I’ve always been skeptical of high-dollar, boutique parts like those found throughout this amp. In my hifi journey, I have only one amp that has endured for me, that I’ve kept for something like 16 years now; Lance Cochrane’s push pull EL84. Its become a yardstick that I use to gauge others, it is a wonderfully sublime and enjoyable amplifier to listen to, and it has been completely reliable for the entire time it’s been in my possession and in near daily use. But it cost me less in total than the speaker binding posts used on the Aum Acoustics amplifier.

That kind of discrepancy is troubling for me, but its hard to argue with success, and Richard’s amplifier is certainly a success. Richard took the circuit and placed it into a much larger custom made chassis to eliminate noise and hum. The parts were all hand chosen and sourced from across the globe for quality without regard for price: Yamamoto sockets and suspensions, Audio Note caps, the wire, the input jacks, the speaker binding posts, the resistors and the volume pots all carefully selected to build the best amplifier possible. The top plate is mirror-like chrome, and the potted output transformers look outstanding. Richard is a perfectionist and it shows; this amp is very simple looking but defines classy and elegant in a precise, minimalist tradition. More details about the build (and the subsequent V2 build) are available here on the Aum Acoustics website.

Glide · to move smoothly and continuously along, as if without effort or resistance, as a flying bird.

So what sounds so good about this amplifier? A nearly complete absence of tension. This is a quality that I’ve only recently realized and defined for myself, but I see that it is at the core of what I am looking for in the sound of an amplifier. In the absence of tension, the sound emerges unconstrained and it feels like nothing is between you and the music. It is uninhibited and free, and this amplifier certainly does that magic trick convincingly.

The Aum Acoustics 45 is super-highly resolving, and my first impression was that it really sounded like a 10Y to me, but not quite the lit-up sounding thoriated type, more like the oxide coated VT-25 that has a harder and denser sound. But this amp has much more low bass tonality and overall richness to its presentation, especially after a long warm up, and I think I’m simply hearing the 45 with the lowest amount of distortion I’ve ever heard before.

Realistic clarity is just through the roof with this amp, but it is still relaxed. Calm, intimate program material like Labi Siffre’s Bless the Telephone is incredibly vibrant and present on the Lii 18 baffles. The character of the voice, the small musical bits and pieces in the recording are so apparent and are presented floating convincingly in the middle of the room in front of you. Placement can be so good with this amplifier and it feels very close to the core of the recording and whatever console effects might be applied. You can see into the mix so easily with this amp once fully warmed up.

And this is an amp that really needs to warm up to sound its best. It can feel decidedly bright to me in the first few minutes, settling in to a deeper and more immersive sound within 10 minutes or so. But its not done. After 2-3 hours or more the liquidity and depth of the amplifier open up even more, like the sea dropping away from the shore into the deepest blue depths, and with a really premium tube set like the EML globes in place, the sound can become just unbelievably present and intimate. It is very pleasing to sit in front of.

According to Richard’s build sheet, at almost $6000 in parts alone the Aum Acoustics 45 Integrated is the probably most expensive amplifier that I’ve ever had in my room. That said, direct comparison to 45 amps (and others) with price tags a level or two below this tell me that many of them are almost there--but not quite. It’s the small differences that we are chasing, the last percent or two that this level of parts and construction reveals, and that's the marrow. Now I know.

As I’ve gained more experience and more perspective, I know what I like right away, and this amp brought a big smile to my face in the first few moments that it played for me. I knew immediately that something new was on display with this amplifier. And although its sometimes tempting, I’ve tried to get away from making “best” statements here on my website. They don't generally age well. But I’m certainly enjoying my time with this amplifier so far! I do think that, once fully warmed up, this is absolutely one of the “most pleasing” sounding amplifiers of any kind that I have owned to date. It just glides where most of the others beat their wings. Super highly recommended.

The Aum Acoustics 45 Integrated amplifier. This is the venerable 45 elevated with the best parts money can buy, all to worship its incredible 1.5 watts of single ended power.

This is a very beautiful amplifier, and it has a clean and classy minimalist look. I’m not really a fan of the mirror chrome top plate that picks up and exaggerates every fingerprint or speck of dust, but it does look good!

The Emission Labs “Lampizator” mesh globe 45 tubes are simply jaw dropping in use. On the right program material, these are incredibly vibrant and alive sounding tubes.

Dual volume pots mean this amp runs without any need for a preamp. I’ve come to almost insist on this functionality in my amplifiers. Without built in volume control they don't last long with me.

This circuit is driven by the 6SN7, and pictured here I am using a pair of 7N7 on adapters, tubes I’ve come to really enjoy in place of the 6SN7. On Richard’s recommendation I picked up a pair of “narrow gap” 6SN7 from 1960 which are also quite good sounding tubes. The 6SN7 family is a big one, so there are many, many choices for the driver in this amp, with both old and new production offering some of the best flavors in hifi if your wallet is deep enough.

Beautiful modern globe 45 are really something special. I’m so glad this tube type is still being produced at such high level.

The 1930’s Arcturus globe 45 are my perennial favorite and this amp is no exception. Excellent antique tubes running in a truly magnificent modern amplifier is a recipe sure to please.