atelier 13 audio
BACKERT LABS RHUMBA XPHONO
We have always loved our LPs.
When we come home to our records, we want exhilaration. Intimacy. A compelling, moving experience. Boring sound simply will not do.
We knew we could get more from our vinyl. So we developed a phono preamp that works in a new way, to produce the emotional beauty we crave from our records. It’s called the Rhumba Xphono. It’s $7,800, and it’s going to change what you hear from your records.
MADE IN THE USA
Backert Labs Xphono 1.1
Bob Backert started the design of our phono preamp with GreenForce, his patented power supply. It’s more nimble than other power supplies. As a result, it propels a “happening-right-now” performance into your listening room.
He then added the tubed amplification circuit from our award-winning Rhythm linestage preamp. Big. Dynamic. Rhythmic. And faithful to the precise tone created by the performers on your favorite recordings. But he wasn’t finished.
One of the founding principles of our company is that owning a tube preamp should be easy. So we’ll ask you about your cartridge, and configure your Rhumba Xphono for your system. You’ll be playing records in minutes. And if you change your cartridge later, adjusting your Rhumba Xphono will also be a breeze.
What about the tubes? Maybe you love tubes, or maybe you’ve never held one in your hand before. Either way, it’s OK. The Rhumba Xphono uses four 12at7’s, one of the most popular tubes in history. They are plentiful, and affordable. And Bob Backert designed the Rhumba Xphono so you won’t need to think about them much, because the Rhumba Xphono babies its tubes. We run them so gently, they might just outlast all of us.
You can easily lift our special tube door to replace the tubes, if you want to see how another tube brand sounds ... after turning the unit off, of course. The tube door makes changing tubes as quick and easy as changing a light bulb.
The 12AT7, also known as ECC81, is a miniature 9-pin medium-gain dual-triode vacuum tube . It belongs to a large family of dual triode vacuum tubes which share the same pinout (EIA 9A), including the low-mu 12AU7 and high-mu 12AX7. The 12AT7 has lower voltage gain than the 12AX7, but higher transconductance and plate current, which makes it suitable for high frequency applications.
Originally intended for operation in VHF circuits, it found wide use in audio as a driver and phase-inverter in push–pull amplifier circuits.
This tube is essentially two 6AB4/EC92s in a single envelope. The tube has a center-tapped filament so it can be used in either 6.3V 300mA or 12.6V 150mA heater circuits.
The Backert Labs Approach
The Phono Preamp Issue
After putting these elements together, Bob Backert went a step further. He decided to tackle the phono preamp problem that nobody talks about.
First, some background: a phono preamp isn’t just one amplifier. The music signal from your records travels through at least two stereo amplifiers in a phono preamp. One immediately following the other. That’s true whether your cartridge is MM, or MC. Phono preamps like this need “two amplifiers in a row”, otherwise, the music signal wouldn’t be amplified nearly enough.
Most phono preamps force these two amplifiers to share the same power supply.
That’s especially unfortunate in a phono preamp, because every amplifier “tugs” on its power supply as it amplifies music. So by doing their job, amplifiers disrupt the very power that feeds them. So if an amplifier shares its power supply with another amplifier, its power gets doubly disrupted.
This is the phono preamp problem that nobody talks about ...
... Two amplifiers in a row, both of them sharing the same power supply, and both of them disrupting the power being fed to them.
But the problem is even worse than you might expect. In a phono preamp, the first amplifier handles the very tiny signal coming straight from your cartridge. We’ll call this tiny music signal Tinkerbell. After passing through the first amplifier, this tiny music signal has grown much larger — dozens of times larger. It is then sent to the second amplifier, and again gets amplified to become dozens of times larger. Compared to Tinkerbell, the music signal in the second amplifier is like King Kong.
When you think about the tugging and disruption that every amplifier inflicts on its power supply, it becomes clear : for the Tinkerbell music signal in the first amplifier, sharing her power source with King Kong over in the second amplifier is bad news. If a single power supply is shared, Tinkerbell’s power source is constantly disrupted by her, and by the King Kong music signal in the other amplifier, which places much larger demands on the power supply. As a result, Tinkerbell has more difficulty getting pure, steady power for the tiny requests she is making to the power supply. This is how most traditional phono preamps are built — two amplifiers in a row, both of them sharing one power supply, and both of them disrupting that power supply.
Fixing the Problem
To deal with this issue, in the Rhumba Xphono, Bob Backert uses a separate, dedicated power supply for each amplifier. Or as an engineer would say it :
A separate power supply for each gain stage
This used to be reserved for phono preamps in the $10,000-and-up range.
Now it’s here, in the Rhumba Xphono.
It’s a phono preamp that sounds like a Backert Labs.
What about the additional amplifier that MC cartridges require ?
In the Rhumba Xphono, that’s a passive amplifier ... a step-up transformer ... or SUT ... which doesn’t need a power supply.
Do phono preamps with “dual mono” power supplies fix this problem ?
No. Dual-mono means “separate power supplies for the left and right channels.” But each channel still sends the music through two amplifiers in a row, one after the other, as we have discussed.
And in other phono preamps, even ones with dual-mono power supplies, those two stages of amplification share the same power supply. So dual-mono power supplies do not address the Tinkerbell / King Kong problem.
Features & Specifications
Inputs - Type
2 x RCA
Inputs - MM / MC
2 x MM or MC - selectable
1 x Balanced XLR
1 x Single-ended RCA
MC x 2 : 61dB or 67dB
MM x 2 : 41dB or 47dB
Via Gain Switch ob Front Panel
Load Options - MC
15 settings via combinations of :
50 / 100 / 150 / 200 / 410 ohm
Load Options - MM
2 Options / Connectors
Power Supply GND
Front Panel Switching
Normal / Low
MM / MC
Global / Local Feedback
Internal Step Up Transformer
Tube Gain Circuit
2 x 12AU7 / Gold Lion Gold Pin
Backert Green Force
EdenSound Audio brass feet
17 x 14 x 5 in
What they say ...
Jeff Dorgay October, 2022
" The Backert Labs Rhumba Xphono 1.1 delivers a near perfect combination of low-level detail resolution, dynamic drive, low noise, and sonic accuracy. Containing four vacuum tubes, it also serves up a slight bit of tonal saturation to help make your vinyl come alive. Where the Nagra Classic paints a larger, bolder picture, the ARC REF Phono 6SE a more clinical, resolving picture, and the VAC Renaissance delivers a warmer, more romantic picture, the Backert achieves incredible balance. Again, please keep in mind all the just mentioned phono stages have an MSRP of nearly 2-3 times the Backert. ... and more if you add the Classic power supply to the Nagra.
Backert also offers something I’ve never seen before in a preamplifier ... auto bias. They claim a bias supply that automatically adjusts itself to deliver the correct bias voltage to whatever tube is installed, delivers the best sonic result possible, and extends tube life because tubes’ bias requirements begin to wander as they age. It is worth mentioning that dropping in different tubes goes without a hitch. In addition, the XPhono has separate, independently regulated power supplies for each of its gain stages.
The sum of all these details adds up to a phono preamplifier that is in the same league as the $TRATO$PHERIC components
" All the techy stuff doesn’t matter once you're into the first track of whatever you're listening to. The Rhumba Xphono sounds great out of the box, and it will improve slightly (but not Earth shatteringly) with time. Regardless of program material chosen, the Rhumba delivers a degree of refinement that keeps you stuck to your listening chair, waiting for the next track. It’s very involving.
Without boring you with track after track minutiae, suffice to say that the Backert phono excels at low level detail retrieval, exciting dynamics, and the ability to create a large sonic field within your listening space. All the reasons you like vinyl in the first place. As mentioned earlier, the tonal rendition is very natural, with the slightest bit of added sonic saturation.
You won't mistake this phono stage for a solid-state unit, but it’s not overly romantic either, i.e. not super warm, gooey, and slow sounding.
Both ends of the audio spectrum are exciting, but again natural. Acoustic instruments like piano, violin, and guitars sound correct. Nylon string’s sound as they should, and there’s more than enough resolution here to hear the difference between various instrument types, and even amplification, if electric guitars are your bag. And worth noting, this phono does an incredible job at decoding and unwinding lousy recordings, thanks to everything mentioned above. This is not a preamplifier that only shows its best side with audiophile approved recordings — again making it much easier to justify the purchase.
Finally, it is extremely quiet, and I'm guessing that has a lot to do with the extensive attention to detail paid to power supply design and regulation. When listening to solo acoustic or vocal pieces, the music played feels CD quiet, yet if this makes sense there’s a fine gradation from very soft tones to a complete absence of sound giving things a lot of presence. Pick your favorite audiophile cliché, it’s that good.
Wait for it
Comparing this phono stage to a few of the crazy money phono stages is like comparing 1500 grit sandpaper to 800 and 3000 grit paper. There isn’t nearly as much difference between the two finest grained papers but going back to 800 will require more work. All but the fussiest of money no object vinyl enthusiasts should be able to live happily ever after with this one. At $7,800, the Backert Labs Rhumba XPhono 1.1 delivers tremendous value for the price asked. Sonics and build are top shelf, and it reveals as much music as others costing more. If you sniff around the internet a bit, you'll see that Backert gear tends to stay in the hands of its owners — it’s nearly impossible to find their stuff for sale used. That speaks volumes. If it meets the outlined criteria for your music system, this one’s a winner "
MADE IN THE USA