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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?

128x128jsqt
lowrider57's avatar
lowrider57
5,417 posts
 
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 believe this preamp uses 12AU7's. Do you know how many and is there a phono stage?

Amperex and Telefunken fit your requirements. Amperex Bugle Boys have deep 3D imaging, they're transparent with a liquid midrange Can be too extended on top in some systems. Older Amperex Command Series are more refined with the same qualities.
Telefunken is a revealing and dynamic tube with excellent 3D sonics. Mids are more upfront. But, they are costly.
Cifte, made by Mazda, has the same attributes as the Amperex Bugle Boys.
A best buy tube is the RCA Cleartop, neutral to warm with extension and air on top.

Read about tube types at 
http://www.audiotubes.com/12au7.htm

Brent Jessee is one of the best dealers and his website is most informative. He also does exchanges on tubes. Upscale does not.




jsqt's avatar
jsqt OP
117 posts
 
I believe this preamp uses 12AU7's. Do you know how many and is there a phono stage?

Yes, it's 2 12AU7's, Mullard reissues from Russia. 

Thanks for the suggestions! I will take @three_easy_payments' advice and live with the Mullards for a couple weeks then possibly check out the Bugle Boys or possibly another pair of Ciftes. 
1markr
594 posts
 
My faves for my Backert.... a pair of CBS 5814a. Just a well balanced sound across the range, but with a lively presentation. I tried a bunch of 12au7s, but always come back to these!
jsqt's avatar
jsqt OP
117 posts
 
My faves for my Backert.... a pair of CBS 5814a. Just a well balanced sound across the range, but with a lively presentation. I tried a bunch of 12au7s, but always come back to these!
Thanks - I'll be checking those out too.

What Backert do you have? What does the rest of your system look like? Thanks!
1markr
594 posts
 
@jsqt
I have the Rhumba 1.2, with upgraded output caps (a pair of Audyn True Copper Max), and an upgraded SR Blue fuse.  Great preamp; responds very well to tube rolling!

Check my system here on Audiogon... a lot easier than trying to describe. Pics are outdated, but the equipment listing is current.
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