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?

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@gladmo 

Good to know that the Psvane ART tubes worked for you. Hope you enjoy them for a long time. I have no experience with tubes and hence in no position to comment.

I will endorse the latest iteration of the Psvane tubes as the best new-production 12AU7's to use in the Backert.  In my experience they are only surpassed by the NOS Amperexes that I mentioned above, which are very hard to find and very expensive when you do.

@twoleftears ,

I did not know that you too tried them. Good to know. It was the Art series…..right?

Yes, the 12AU7-S ART's surpass new-production Mullards (supplied by Backert as standard) and Genelex Gold Lions.  I don't know of any other new-production 12AU7's that would be contenders for the crown.

@oddiofyl : Would you please explain in technical terms why you say "With respect to 12sn7 adapter,  I would personally only use 12au7 and / or their exact pin out equivalent,  especially on a $7500 preamp". I find many of your posts informative and helpful. Jeff