Backert Labs - Rhythm 1.3 line stage

Adventures with a vacuum tube preamp

I have yet to give up on solid-state components for HiFi systems entirely; however, my love affair with vacuum tube circuitry is stronger than ever. 

While auditioning the latest iteration to the top-line Rhythm 1.3 linestage from Delaware-based Backert Labs, I got a sense of the same unmistakable mojo I feel when listening to recordings played on other well-designed and constructed tube gear.

In my years as a professional listener in music production and as an audiophile at home, I’ve had lots of exposure to tube gear for recording, mixing, mastering, and playback - some good, some great, and some downright ugly sounding. Unfortunately, I can’t know how many audiophiles have had a chance to really hear what high-quality modern tube gear can bring to the party. Current vacuum tube designs differ from your grandfather’s Telefunken console or your father's McIntosh. Yes, there are some notable examples of past glory in vintage offerings (Marantz Model 9, ARC SP-3a, etc.). Still, I like the union of imaginative new approaches combined with classic tube design, evidenced in the best of the new tube componentry.

And that leads me back to Backert Labs, which I now consider one of the top seeds for the New Tube Gear Invitational Tournament.

Deets

The Rhythm line stage evolution includes the 1.1, 1.2, and 1.3. New for the 1.3 is a choice of two balanced XLR outputs and two unbalanced RCA connections. Inputs 1 and 2 are balanced, with the remaining three inputs unbalanced. The 1.3 uses a dual-mono power supply incorporating a technology Backert Labs calls GreenForce. MSRP is $10,750. Add $450 for the brass bottom panel.

The front panel is simple but has all it needs: from left to right, a “bat” style mute and stereo/mono switch, input selector knob, volume knob (motorized for remote control), balance knob with a middle detent, and on/off switch. Some purists may balk at a balance knob, but I’ve wished for one on more occasions than I’d admit. Okay, I’m admitting it now. 

Check out the specs box at the bottom. I’m not usually a specs guy, but those are darn impressive.

There is a treasure trove of information on the Backert website.

For example, a low output impedance of less than 80 ohms (Z) featured in the Rhythm significantly minimizes signal loss. Driving the fragile output signal over a long cable run will gently roll off high frequencies when the output impedance is in the 1K ohm range and higher. If the line is unbalanced, noise and stray RF pickup is a real thing. Although the math says anything over a couple of meters filters a tiny amount of top end in a high Z, single-ended output, most folks consider it audible. With a Rhythm 1.3, having Lo Z out for balanced and single-ended means you’re covered - no matter what. 

Backert achieves this in the 1.3 without using the more common cathode follower circuit to load the tube down for LoZ. Generally speaking, cathode follower circuits don’t seem subjectively quite as compelling and alive sounding as other approaches like transformer coupling. I don’t know what the Rhythm 1.3 uses, but whatever it is sure sounds good.

Green Force

Wait, is this a bill in Congress making everybody go solar and buy electric cars? Nope.

It’s the term that designer Bob Backert uses to describe a different and creative way to use the power supply in Backert Lab products. I’m almost all tech’d out, so I’ll let y’all read about it on the Backert website. According to Backert Labs, their GreenForce power supply is a significant portion of what is responsible for the Rhythm 1.3’s sonic agility. Part of the design ethos resides in using much smaller capacitance than is typical, resulting in great speed and short recovery time. I see no reason not to take them at their word.

The rest of the upgrades for the 1.3 consist of the following:

• Improved output capacitors:  The highly seductive V-Cap ODAMs now handle output duty

• Improved power supply capacitors:  the famously dominant V-Cap PTFE capacitors now drive our GreenForce power supply — with copper foil, an exotic capacitor that is unheard-of in any audio power supply – in any any power supply at all, actually

• Improved circuit board:  double the copper in each trace

• Improved feet: the Rhythm 1.3 features the excellent Terracones, from edenSound

• Improved stock tubes: the Gold Lion gold pin 12au7’s for maximum pace, inner detail and resolution

• Our latest circuit: gain stage and power supply regulator designs benefit from our latest research

Backert also uses a circuit that automatically biases the tubes. As with all Backert line stages, other compatible tubes in the 12AU7 family tree may be accommodated - e.g., a 5814A or a CV4003. 

I hear that a new 1.4 model is on the way that makes you a sandwich on request - as this was the only feature they could think of to add.

You Know It’s Gonna Make It That Much Better

The evening Dr. Vinyl and his son dropped it off at mi casa, I immediately enjoyed the sound - even if I had a few slight reservations. 

We needed more time at the end of a long day to get fussy and tweaky, as we are typically wont. So Dr. Vinyl simply showed me the tube options he had brought along, and we quickly listened to a few tunes while doing a bit of tube swapping. Tube rolling on the Rhythm is much easier and quicker than other gear; for a few reasons. First, the pair of 12AU7s are easily accessible and small tubes cool off quickly, which makes tube swaps a breeze. 

Tube rolling is encouraged by Backert. Experimentation is aided by purchasing only a pair of these lower-level signal tubes - which is not a financial stretch for many of us in The Hobby. Plus, 12AU7s aren’t one of the more popular and highly sought-after NOS types like a 12AX7 or 6DJ8, so you have the perfect recipe for neurotic and affordable rolling to your heart’s content.

I had been listening to the Rhythm 1.3 for a few weeks - with intervals of switching back to my reference VAC Master Preamplifier. I still enjoyed the VAC more, but the Rhythm was not exactly chopped liver. My first impressions were excellent. 

As time went on, I did a lot of tube swapping. I like that sort of thing. It was fun, if not definitive. I could season-to-taste the essentially great sound of the 1.3 with different tubes - gee, what a surprise. I didn’t, however, find a magic type that seemed to give me everything; articulation and detail, dense and textural midrange, deep and full bass - with no sense of bloat.

During an enjoyable phone call with Backert Lab president Andy Tebbe, he asked if I’d like to listen to a tube type that Backert now ships with 1.3s. Is the Pope Catholic? Of course, I replied.

Soon after, my partner Linda noticed a package at the door on a Sunday morning. The mystery tubes! Suddenly my Sunday plans changed, and I was off to the tube-swapping races.

After installing the tubes, I quickly streamed “God Only Knows” by The Beach Boys, followed by “Wouldn’t It Be Nice” - to warm up those NOS 12AU7s and in deference to Linda, who loves The Beach Boys. Okay, I love em, too.

Linda and I, joined by our cat Speedy sat in rapture. Wow. 

Something different was happening to the sound. Before, it had been damn good. Now it was great.

Top-to-bottom tonal balance, along with imaging, was outstanding.

To my ears, the 1.3’s imaging performance was one of the few areas that fell slightly short compared to the VAC. But hey, the Rhythm is almost a third the price of the VAC. Moreover, after playing many more tracks with the new NOS tubes supplied by Andy, imaging was much improved. 

I term these mystery tubes because of Andy’s request they remain unnamed so as not to raise the price on the used market. However, I’m sure any Backert owners with older Rhythms can contact them to arrange for a pair.

During this review period, my system consisted of the following:

TW Acustic Raven LS with Raven 10.5” tonearm and Dynavector XV-1t cart, Forssell Technologies MADA-2a DAC, VAC Master Preamplifier with phono stage option, Ampsandsound Zion Monos power amps, QLN Prestige Five loudspeakers with Iso Acoustics feet, mostly Cardas Clear Beyond cabling, power bar, and power cords, Acora Acoustics black granite equipment racks, and a Profitec Pro 500 espresso machine with Counter Culture Big Trouble beans.

Streaming Some Tunes

I’ll get more specific about the stew of sonic goodness I observed while listening to the Rhythm 1.3.

Album after album, I enjoyed just about everything the Backert linestage brought to the party. 

I arrived at my listening impressions using balanced outs from the Forssell DAC into the Rhythm and single-ended Cardas RCAs into the Zions.

This Is Not Our First Goat Rodeo from Goat Rodeo has been a favorite of mine for enjoyment and gear demos. I usually play the vinyl; however, the digital is excellent. The Track “Waltz Whittman” is a fav, although the entire album is phenomenal.

With the Rhythm 1.3 in situ, YoYo Ma’s gorgeous expressiveness and cello tonality were goose-bump-inducing. Edgar Meyer’s double bass had a satisfying authority and low end. Chris Thile’s mandolin was delicate and forceful. Pinpoint imaging across the stereo spectrum with lots of front-to-back depth. The upper midrange and lower treble areas were reproduced with a sense of sweetness - but not too sweet. Reality is not always silky smooth. 

I love components that exhibit a clean and fast leading edge to transients without sacrificing the holistic musical gestalt of a fine recording. The VAC Master Pre does this better, but the Backert is close. 

Becca Stevens is an artist I’ve loved and worked with for many years. Her album Becca Stevens & The Secret Trio is another example of her beautiful voice and writing talents. When listening to the track “We Were Wrong” I got a familiar tingle with much more to do with the music than the gear, but good equipment doesn’t hurt. 

I heard an impressively tactile and organic presentation with the Backert pre. My listening notes say rich midrange and wooden, quick and clean high end, with no hype.

Next, I compared a few recordings of Bach’s Brandenburg Concerto No. 3 in G major. I know, a classical music chestnut, but I like it.

The 1990 DGG digital recording of the Chamber Orchestra of Europe with Christain Gansch conducting is good, IMO. 

The Rhythm 1.3 hung in there to reproduce all the fast leading edge attacks of the steeple-chase, Allegro movement. The harpsichord tinkle was extremely clear. Maybe a bit too clear due to its prominence in the recording. The strings, although dry sounding, didn’t have much glare or graininess; it’s DGG and an early-ish digital recording, so draw your own conclusion.

The sumptuous 1967 analog recording of the same piece by Karl Richter conducting the Muchener Bach-Orchestra was much fatter and zoftig. The harpsichord is audible but more realistically placed in the mix. Loud, harpsichords ain’t. All these differences between the recordings stood out in bold relief, which is what I want a component to tell me. I’ll also add that this contrast was not at the expense of musical enjoyment. I could easily relax into either version of this Baroque counterpoint speed flex.

Victoria Victoria (joined here by guitarist Charlie Hunter) is a group most readers may need to learn about. Their latest album, To The Wayside, is my recent favorite. The mostly dry and upfront recording is a perfect presentation for singer Tori Gingrich and backup singer Maia Kamil with a rhythm section of Mr.Hunter (on bass and guitar) and George Sluppick on drums and percussion. Kudos to recording engineer and mixer Stephen Price.

I know this recording very well, and the Backert pre did an exceptional job reproducing all the midrange warmth and phat bottom end. I resisted the temptation to add any hype to the upper frequencies when I did the mastering cause I wanted it to live in a chocolate-flavored space. It almost has a classic Yacht Rock tonal vibe, although I wouldn't classify it as such musically.

I’ve yet to hear my QLN speakers sound quite as controlled and big on low-frequency content - until now. Score another for Team Backert.

My final playback impression is an album I frequently listen to in its 45 rpm, six-sided, vinyl version - Up by Peter Gabriel. I love the music and consider it an exceptional recording. The digital version isn’t bad and undoubtedly more faithful to the artist’s intent. I like the vinyl. 

On the song “No Way Out” there are, by my count, five separate bass parts that weave in and out - sometimes playing simultaneously. This kind of low-end is uber mixer Tchad Blake’s world, and no one does it better.  Tchad paints with low frequencies on this album with veracity seldom heard anywhere else. And there is not a smidgen of extra top end on these mixes to balance out the tonal landscape - which increases the difficulty of doing so. A HiFi system has to be firing on all cylinders to get the most out of this fantastic recording.

The Backert pre was more than up to the task. It engagingly rendered all the midrange textures while pulling back the curtain on all that luscious low end. At the top of the track, I hear what sounds like a sub-harmonic processor on Tony Levin’s upright bass. The Rhythm 1.3 articulately went down the basement, similar to a solid-state preamp. I heard not the preamp's limitations but the Prestige Fives' low-frequency cutoff. Beyond all this, once I shifted from analytical listening (which was super easy), the Backert presented the music as a whole cloth with a tight weave. The imaging was superbly spacious as well. Peter’s concerned and confessional vocal performance was at the forefront of my awareness.

Wrap It Up

I found my time with the Backert Labs - Rhythm 1.3 linestage a real treat.

Thanks to Dr. Vinyl for bringing it and Andy Tebbe for the conversation and vacuum tubes. 

Backert Labs is a small company that is not on everyone’s radar but should be. Bob Backert has been at this design thing for a while, and it shows. 

Yes, you can get a bit higher on the audiophile mountaintop. But it's going to cost you a lot more. However, I’ll call the Rhythm 1.3 a winner in the $10K-and-under market niche. 

It’s a reasonably affordable linestage with sonic attributes nearly equal to the finest solid-state and vacuum tube designs - the type of tube gear that leans slightly to the clean side without sacrificing musicality. 

If this sounds like your thing, do yourself a favor and find a dealer to check one out. You won’t be sorry.

Highly recommended.

TrackingAngle is positively elated to welcome Dave McNair to our team of distinguished writers! Below is a short bio—ed.

Dave McNair has for 44 years been a professional recording engineer, mixer, producer, audiophile, and for the last 22 years, a mastering engineer.  After years of residence in NYC, Los Angeles, and Austin, he now resides in Winston-Salem, North Carolina, with his partner Linda and their cat, Speedy , He operates Dave McNair Mastering and spends his free time listening to records, reading, meditating, cooking, hiking, cycling, and swapping out hi-fi gear in search of a better sound.