The Backert Labs Rhumba 1.2 Extreme


      I first met Bob and Gary Backert when I dropped off
my JMA Peach 2 off for repair. it was then that I first
heard the Rhumba 1.2 . I had brought a few of my 
favorite tracks with me to try out. I was very impressed
by the quick paced, rhythmic sound. I looked at what he
was using for components and realized that it was the 
preamp that I was really hearing. 

      Over the next month Bob fixed the Peach and 
some other items that he felt would affect  long term
reliability so I had him take care of those. I had already
decided to audition a Rhumba and wanted the best out
of the Peach 2. During that month I had done my research
and found that he made 3 different preamps, the Rhumba
1.2 at $3500.00, the Rhumba 1.2 Extreme at $5500.00
and the top of the line Rhythm at $7500.00 . All 3 are of the
same basic design. The Rhumba 1.2 does not include the 
auto bias tube circuit while the other 2 do. All three contain
Bob's patented "Green Force" power supply but with 3 
different quality levels of film caps. The Extreme is basically
a slightly toned down Rhythm in the less complex and 
therefore less expensive Rhumba chassis. 

      When I picked the Peach 2 up I advised Bob that I wanted
to audition the Rhumba 1.2 but had a  list of things from the 
Extreme that I wanted to incorporate either now or later, Bob 
advised me it would be more cost effective and less invasive
to audition an Extreme, I agreed. I spent the next month running
in the Peach and accumulating 3 pair of NOS tubes for the 
Extreme. I already had 3 different power cords. I wanted this 
to be a level playing field. In the end I needn't have bothered
as it was never much of contest.

      I picked up the Extreme on 5/17 intent on spending the next
week breaking in the 3 pair of tubes and voicing the 3 power 
cords.I don't change equipment very much and on top of that if
I did make the change it would be the most that I had ever spent
on any one component, I wanted to be sure while I was in my 
14 day money back window. I had which PC and which tubes
figured out by the end of that weekend. I listened to the Extreme
all week and the more I listened the more I knew that I would not
be returning it. Friday of memorial day weekend rolled around and 
I had the next 5 days off to listen. The Peach went back in Thurs.
night and played all night as it hadn't been used in a week. I 
played it all day Friday, then the Extreme went back in on Sat.
The Peach went back in on Sunday and made it for about 4 hours
and DONE. Even with the least favorite PC and tubes the Extreme
clearly bested the Peach by a lot, with the preferred PC and tubes
it just walked all over it in every aspect plain and simple. 

      The last bit of top end sparkle and detail that I had been chasing
for years is finally mine. Crystal clear and detailed without a hint of 
grain or brightness. The mids are rich and meaty, beautifully textured
and layered. It was the bottom end which really surprised me. It is
DEEEEP!!!!! No mush or gray area, think razor sharp, black and
white. The sound stage is wide and deep. Performers and instruments
are located and placed properly with space around them. The stage
extends well outside of the speakers and makes them just disappear .
The attack is quick like a shot while the decay is gradual, not the on/off
that I was accustomed to. This presents a BIG sound and really makes 
you feel that you are listening live. The music doesn't sound reproduced
it is conveyed. The sound is rhythmic and quick and with wonderful 
impact. It is ruler flat with no bloat or bloom.

        I spent a lot of money on this and feel like I made out like a bandit 
for the added amount of enjoyment and pleasure that it has afforded me.

        I was going to highlight some of the differences between the Rhumba
and the Rhumba Extreme but this is already much longer than I had 
intended and I felt compelled to write it. I can do a follow up post if anyone
wishes on what separates the two. For those of you who made it this far
I thank you for your time in reading my commentary.
                                                                                Happy listening, Woody

      

      
      
      

      
woodyandchristy
Thank you so much for your write up of the Rhumba 1.2 Extreme. I've always been curious about these preamps. I may have to hear one in my own system. :)
Woody, what 12au7s did you settle on? 
        You are welcome as it was a pleasure to write about my
   experience with Backert Labs and their products, both of 
   which I consider superior in every aspect.

        As for the tubes I have 4 different pairs and another on
   the way. All tested at NOS levels.
   #1 - 1955 RCA 3 mica black plate D getter 5814A, way too
           lush. May be good in a bright system but not my thing.
   #2 - 1959 RFT long plate halo getter mil spec12AU7, it is
           basically a Phillips/Amperex made in France and sounds
           like it. Nice tube, does everything well but doesn't
           distinguish itself. I'm on the fence with this one.
   #3 - 1952 Raytheon 2 mica, short black plate, D getter, 5814
,            This is "The Bomb". Great extension top and bottom.
            The mids are rich and meaty. Extremely detailed and
             focused throughout. My only criticism is when driven
             extremely hard the top end gets a bit grainy but we
             are talking very, very loud, not where I listen. I liked 
             these so much That I bought another pair from the
             same batch while I could. 
     #4 - 1958 CBS/Hytron short black plate, 2 mica, D getter 5814.
             I can see why these are well thought of. A bit more
             polite than the Raytheons. Better on a bad recording,
             not as good on a good recording. They are an easier
             listen but ultimately not as satisfying to me. A definite
             keeper to me.
      #5 - ON THE WAY, 1958 Amperex marked Beckman 7316
              long plate, D foil getter CT0 ^8L. We will see if all the
              hype is deserved. 
       Look up Mike Bower on Ebay, extremely knowledgeable
       and honest on 12AU7, 5814, 6189's
Woody, I don't know this from experience, but from research, you may  prefer a later Amperex 7316 or 12au7.  My understanding is that the D getters are more laid back and the later Amperexes have a more lively or vivid sound.
@woodyandchristy :

" I was going to highlight some of the differences between the Rhumba
and the Rhumba Extreme but this is already much longer than I had
intended and I felt compelled to write it. I can do a follow up post if anyone wishes on what separates the two."

Woody, can you share more about the differences between the base 1.2 and the Extreme?  

Thank you!
        While repairing and modding tube equipment for years, Bob
    has developed two mods/circuits, one that he incorporates into
    all three preamps and the second which is included in the top
    two versions.
        The first is the "Green Force" power supply which
    uses a series of film caps in place of a large group of
    electrolytic caps, this is patented. I initially had reservations
    about how it would do on the bottom end, after hearing it I can't
    believe how much more of a deep and focused bass I have.
        The second is the "Auto Bias" tube circuit which does what 
    its name implies whether your tubes measure at NOS levels,
    getting near minimum or anywhere in between. Now to the
    differences.
                        Rhumba 1.2    MSRP $3500.00 usd
        #1 - Polystyrene caps in the "Green Force"
        #2 - REL PPT Theta output caps
        #3 - J/J 12AU7 tubes
        #4 - "Auto Bias" circuit NOT included 
        #5 - Polypropylene caps in "Green Force" regulator circuit
        #6 - Rubber feet
        #7 - Sound dampening applied inside of top cover and sides
               as well as the outside of the "Tube Gondola", more on 
               that below.
                         Rhumba 1.2 Extreme    MSRP $5500.00 usd
        #1 - Upgraded polystyrene and Mundorfs in the "Green Force"
        #2 - Mundorf 2015 MCap Supreme EVO Silver, Gold, Oil outputs
        #3 - Psvane 12AU7 tubes
        #4 - "Auto Bias" circuit IS included 
        #5 - Upgraded polypropylene caps in "Green Force" regulator
        #6 - Four, Edensound "Terracone" footers
        #7 - Premium Dynamat applied in same manner as #7 above
                         A few final thoughts:
        #1 - The "Tube Gondola" is accessible via a clear plexiglass
                cover on the topcover secured with two thumb screws.
                It is a gondola shaped well with raised sides so none of
                the innards are visible except the two ceramic sockets
                and the axle connecting the front mounted input selector
                knob to the actual switch which is toward the rear which
                passes through it between the sockets. The Furutech
                goldplated IEC with integral fuseholder (both models)
                is on the back panel so any adjustments or changes
                can be done externally - well thought out and implemented.
         #2 - Apparently some of the Rhumba 1.1's were slightly noisy
                and this is no longer an issue as circuits were tweaked, 
                dampening was added as well as strategically placed
                gasketing (Terracone feet on the Extreme). With the volume 
                turned all the way up and tapping anywhere on the case 
                you hear NOTHING out of the speakers, it is completely
                quiet.
          #3 - This is a tube preamp so it's going to be at least warm if not 
                  hot right? WRONG, in my 72 f room with my Snap On 
                  infrared thermometer it measures 82 f while my Wadia 15i
                  measures 80.5 f and my Genesis Digital Lens is 84.3 f
           #4 - After spending 2 months with the Extreme I'm completely
                  satisfied with the added performance and enjoyment that
                  it has afforded me. Too often in this hobby you spend a lot
                  to get a little. I spent a lot, got a lot and I'd do it again in a 
                  heartbeat.
                                                                        Happy listening, Woody
        
        
        
Woody,

Thank you for your detailed response. Appreciate it.

Were you able to listen to the Rhumba 1.2 vs. the Extreme head to head?

If so, any comments about sonic differences / gains as one moves up? 

Thanks.

        Dave,
                  I did not compare head to head. I can say
                  that when I first heard the base Rhumba 1.2
                  in Bob's workshop system I was very  
                  impressed and that is what got me going on this.
                  I only auditioned the Extreme in my system as
                  by the time I added the "auto bias" circuit,
                  upgraded caps in the "green force" and outputs, 
                  and the Edensound terracones to the price of the
                  base model it just made sense to spring for the
                  Extreme.
                                                                                  Woody
Thank you, Woody. I may be going this route also. I had considered the Rhumba 1.2 Extreme, but held off since there wasn't any feedback on it by owners or reviewers. Backert came highly recommended. Keep us updated on your impressions and thoughts. 
Just posting as further encouragement of future updates...
Woody we thank you for the kind words.  Your knowledge of our Rhumba 1.2 and the Rhumba 1.2 Extreme - impressive!!  One thing: the power supply capacitors for both models are polypropylene.
Thank you for your support,
-Andy