Tube Rolling Advice for the Backert Labs Rhumba Extreme?


Tomorrow I have a Backert Labs Rhumba Extreme 1.2 being delivered, which has been upgraded by Backert to 1.3 specs. It will be driving the Luxman MQ-88uSE and the front end is a Qutest with M Scaler (Innuos Zen MK III server/streamer). Speakers are La Scala IIs, placed about 15' apart in the corners at a 45º angle. Soundstage is excellent and expansive with remarkable placement of instruments across the sound field.

If all goes well it will be replacing my L-509X, which is currently only being used as a preamp for the MQ-88uSE, so it’s being underserved in my system and will need to find a better home.

I am interested in any advice about tube rolling with the Backert Labs pres. With the Chord digital front end, I am getting a very layered, dimensional, detailed sound and thanks to the Qutest filters I’m able to adjust filters to best match the amplification. The MQ-88uSE has a gorgeous, full, warm sound and right now the 509X’s solid state pre is giving a nice sharp, detailed, and dynamic profile to sharpen up the tube sound a bit.

I don’t want a syrupy or bloated tube sound, more airy and detailed on the top with holographic imaging with solid heft on the bottom end. I’ve replaced the preamp tube in my Cronos Magnum II with a Cifte and was really happy with the impact on the sound.

The Backert comes stock with new Mullards, which I expect may have a slightly warmer sound than what I’m chasing.

Any advice?

128x128Ag insider logo xs@2xjsqt

@hifiman5 and @milpai thanks for the updates! I'm glad to see this thread continue, as I think there are a lot of Rhythms and Rhumbas out there but they don't get talked about much in the forums. I've done a 12AU7 inventory recently given the events in Eastern Europe and I have 4 Mazda Cifte's, 2 Genalex, 2 Russian Mullards, and 4 Brimar CV004s, so I should be in pretty good shape with the tubes I have now to weather any shortages. This weekend I'm experimenting with swapping the Brimar CV4003's back into the Rhythm and this time without O-rings. @hifiman5 were you ever curious about Bob's Xphono phono pre? I have just gotten back into vinyl since January and I have a Parasound JC3+ on order to complement my current SL-1200MK2 and my future Pure Fidelity Harmony. The Luxman and Xphono both looked really good but a little over my budget for where I'm at with vinyl these days. However since Oreas were mentioned somewhere in this thread, here's something I found - I am using an extra glass panel from my Naim Fraim to support the SL-1200Mk2, and I experimented with supporting it by either 3 Stillpoint Ultra SS vs 3 Isoacoustic Orea Indigos. The Oreas definitely seemed more natural and relaxed than the Stillpoints. Stillpoints seemed to tighten up the bass to a fault - I enjoy a bit of that analog fat bottom end (think a Fender P Bass and Ampeg cabinet) and the Oreas seemed to do a better job of tightening up the space between the notes while maintaining the natural presentation and flow of the music. 

@jsqt Interesting that you mentioned not using the damping rings when you install the Brimars. I just put a new matched pair of Gold Lions in my pre last night as the tubes had been in circuit for over two years. After having read others experience with and without dampers, I installed the new tubes without the dampers. I’m looking forward to listening this weekend. I mentioned the Oreas in my previous post and agree entirely with your assessment of their impact on the system’s sound. As far as phono preamps go, I have no doubt that the Backert is great but I love what my Luxman has done for the sound of vinyl in my system. The vinyl I have been receiving is really flat and quiet. Amazingly so.  I have so many silver and gold discs as well as a vinyl collection dating back to the 1970s that I plan to stay with hard media rather than adding download capabilities. 

@jsqt ,

Since you have such a nice inventory of the 12AU7s, I would like your thoughts IF you get a chance to listen to the Psvane's new ART series. They have bowled me over. The work "mesmerizing" comes to my mind.

As this thread is about tube makes and models that do especially well in Backert preamps, I'm going to reiterate my recommendation of the--admittedly rare and costly--Amperex 7316.  This is what Brent Jessee has to say about them.

Simply an amazing tube. Amazing both because it sounds so incredibly good, and amazing how rare it is today. The 7316 was made by Amperex in Holland, I have never seen this in any other brand, nor have I seen it made by Amperex North America. It is a medical grade/aircraft equipment grade super low noise tube, not sold to the general public. It is Amperex's answer to the ECC802S produced by Telefunken, and the 10M series made by Mullard. Most have the Bugle Boy on the label, although I have seen plain Amperex labels, and OEM labels such as Beckman Instruments. The 1950s vintage with the long plates and D-getters are to die for. They are among the best sounding and rarest 12AU7 around today. Don't miss the 1960s halo getter version of this tube, as well. They sound nearly as good as the D-getters and are usually half the price. Very few dealers ever have the 7316 of either type in stock, well worth seeking out and worth the higher price. We try to keep a few of each type in stock, but it is not easy. Better buy them when you can find them!

Unfortunately, it's all true.

@milpai I’ve just started my tube rolling journey with my Rhumba Extreme 1.3, and my first change was to the Psvane Art Series. Holy mother of tubes! After only 9 hours on them, they are already a giant leap ahead of the stock Mullard tubes. Thanks for rec! After the first hour, they excelled in all areas except bass extension and the vocals were still somewhat thin. But now, the sub-bass region is gaining some weight and overall, in the Extreme 1.3, they make my system sound really incredible. I’m looking forward to the other tubes that are en route to me, but i think these will be hard to beat... I suspect even by the NOS stuff.

Edit:  By the way, I'm not using any damper rings on the tubes.  The Backert pre is on Townshend isolation pods and the cables going to it are also isolated from vibrations.