Cube Audio Nenuphar Single Driver Speaker (10 inch) TQWT Enclosure

Cube Audio (Poland) designs single drivers and single driver speakers. 

Principals are Grzegorz Rulka and Marek Kostrzyński.

Link to the Cube Audio Nenuphar (with F10 Neo driver) speaker page:

Link to 6Moons review by Srajan Ebaen (August 2018):


Parameters (from Cube Audio):

Power: 40 W

Efficiency: 92 dB

Frequency response: 30Hz - 18kHz ( 6db)*

Dimensions: 30 x 50 x 105 cm

Weight: 40 Kg

* Frequency response may vary and depends on room size and accompanying electronic equipment.
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Showing 48 responses by rwpollock

Well, I just have to be sit here with my SIT-2.
Very happy actually. I prefer it to my SIT-3 and Bakoon.

Speaking of which, I'll be reducing my inventory before the end of the year.
Anybody interested in a FirstWatt SIT-3 or Bakoon AMP-13R?

Nenuphar journey, part 3.

Now that the Nens were broken in, it was time to try different amplifiers. I had been using the LTA Z10 integrated. It sounded fine but lacked enthusiasm, a certain jump factor. Time to explore my FirstWatt collection.

First up was the J2, which actually exceeded my expectations. It sounded clearer than the Z10. The bass was fine, but the soundstage only average. Perhaps a pre would expand the soundstage. PRaT was good, restoring the jump factor. All in all, a decent match, so if you have a J2 don't throw it away. :-)

To be continued....
My Backert preamp is an original Rhythm, the 1.1 (they now sell a 1.3 version). There is a used 1.1 for sale now on Audiogon for $3500. The only thing I don't care for is that the Backerts invert polarity/phase so you have to reverse the red/black speaker connections. No big deal if you don't switch you gear around. That said, it's fairly easy to tell if things are inverted; it is kind of like pushing your music uphill....

Do you know the selling price?
So, there was a pair of SIT-1 monoblocks listed for sale this weekend on Audiogon. They went in a few hours, and I missed them. Did anybody here pick them up?

On a side note, FirstWatt has a new model out.
"The F8 revisits their most popular J2 model but simplifies the front end for just three signal-path devices per channel. It applies current not voltage feedback and improves on the J2 specs on bandwidth and damping factor."

The output impedance is 0.2 ohms, which puts it between the SIT3 and the J2, but far below the SIT1 and SIT2 at 4 ohms.

- Robert
SIT-1 monos (when they can be found) are much more expensive than than the SIT-3s. Occasionally you will find a SIT-2 for sale, usually cheaper than a 3. The SIT-2 is stereo and provides that immediacy of a tube SET amp. The Bakoon 13R integrated ($5K used) sounds good with Nenuphars, although I prefer going FirstWatt.

For a preamp, the Pass Lab ones make for a great combo. On the tube side I have used LTA and Backert, with Backert being my preferred choice. Easy tube rolling if you enjoy that.

- Robert
Has anyone tried a Valvet amp with a Nenuphar?
I've sent an e-mail to Alfred at Highend-Electronics. Will let you know what he replies.
 - Robert
No, I didn't listen to the BASiS; I'm not really a bass addict. In addition,I believe they are quite expensive (11,000 euros). Even the smaller stand alone subs are sold at Refined Audio for $5,500 -- which Jon admits is expensive.

- Robert
It is generally recognized that overdamping the Nenuphars is not a good idea. At 6moons Srajan wrote in his review of the First Watt SIT-3 about driving the Nenuphars:
" won't be surprised to learn that the SIT-1 and SIT-3 were the perfect antidotes; better than the F5 and F7, very much better than the Pass Labs XA-30.8, radically superior to 200-watt class A/B specimens of the 1Mhz ultra-bandwidth persuasion."

As an example of the last, the Soulution 501 has a damping factor of 10,000 (which would correspond to an output impedance of 0.0001 ohms). The Mola Mola, a class D amp, has an output impedance of 0.003 while the Bryston 4B clocks in at 0.016 ohms. Still too low to be of interest.

Moving on to a couple of tube amps, the Audio Research VT80 has an output impedance of 0.12 while the Aesthetic Atlas is 0.25. With OTL amps, the LTA Z10 impedance is 1.2 ohms and their Ultralinear is at 1.6 ohms.

Looking at the solid state amps that Sjaran ranked we see a consistent pattern:
SIT-1  4 ohms
SIT-3  0.26 ohms
F-5  0.025 ohms
F-7  0.01 ohms
Pass XA 30.8  0.007 ohms

Here are the output impedances of the First Watt stable:
F-1  80 ohms
F-2  15 ohms
SIT-1  4 ohms
SIT-2  4 ohms
J-2  0.4 ohms
SIT-3  0.26 ohms
F-4  0.2 ohms
F-3  0.12 ohms
F-6  0.06 ohms
M-2  0.05 ohms
F-5  0.025 ohms
F-7  0.01 ohms

Which leads to the exit question: Has anyone listened to the F-1 or F-2 with the Nenuphars?

Yes, it is high.
Here is a link from FirstWatt on the F1:
"It has both balanced and single-ended inputs. The input impedance is nominally 80 Kohm, and the output impedance is 80 ohms."

And from the F1 manual:
"Input Impedance, unbalanced  50 Kohms, 8 ohm load

Output impedance  80 ohms"

In his 2004 review of the F-1, Dick Olsher wrote:

"Current drive offers a major alternative to the speaker-amplifier interface. A transconductance amplifier is operated as a current source with a high source impedance relative to that of the speaker. The output impedance must also be linear and frequency independent. An ideal current source would possess an output impedance so large as to be considered infinite relative to that of the speaker. The F1's 80-ohm impedance is certainly adequate in this regard."

Any thoughts on the output impedance question? IIRC, the 13R prides itself on low output impedance which should translate in a high damping factor

Just to complicate things, I was reading back through the thread and came across toetapaudio's comment from a year ago (6/20/19):

"We are getting great results driving the Cubes with Mola Mola Makua/Kaluga’s and look forward to trying Bakoon amplification soon with the Cubes."

The Kaluga's output impedance is listed as <0.003 ohm with a damping factor >4000.
Go figure.
So, in which state do you live?
I have met a few local audiophiles through classified ads, and I did sell a pair of Triangle floorstanders to a neighbor. He drives them with his Sony receiver and is quite happy. He felt no need to upgrade anything else.
Bakoon writes:
"The patent-pending JET Bias circuit has brought the SATRI circuit to a whole new level in terms of electrical performance and sound quality. Our Circuit is now reborn and renamed as the JET SATRI circuit, an ultrafast, wide bandwidth, full discrete design with zero negative feedback. It is also our first circuit that doesn't even use output emitter resistors, resulting in lower output impedance than ever before, with direct, ultra fast response to the loudspeakers."

So the 13R has "lower output impedance than ever before" which means higher damping than before. It makes one wonder what their older (and $3K more expensive) 41 amplifier would sound like with the Nenuphars.

- Robert
Speaking of different solid state amplifiers, I was doing some reading on damping factors and came across a link to two Gold Note amplifiers out of Italy, the IS-1000 (integrated) and the PA-1175 (power amp). Both models have a DF option which can be changed on the fly. The high setting has a DF of 250 while the low setting is at 25.

Has anybody listened to one of the Gold Note amps?
 - Robert
"Curious if I'll be able to pull off a high gloss black piano paint job."

Try Ferrari Red. :-)
It would look good with the gold drivers.

<<help decoding these specs and opinion on compatibility with the cubes...
Output Impedance <0.8 ohm
Damping factor >10>>

Yup, DF = 8 ohm/0.8 ohm = 10

Here are some other amps for comparison:

Mola Mola (Class D) = 0.003 ohm, so DF = 2666  <== avoid
Bryston 4B (Class AB) = 0.016 ohm, DF = 500  <== avoid
Aesthetic Atlas (zero feedback hybrid) = 0.25 ohm, DF = 32
FirstWatt SIT-3 = 0.26 ohm, DF = 31
FirstWatt SIT-1 = 0.27 ohm, DF = 30
LTA Z10 (ZOTL) = 1.2 ohms, DF = 6.7
Audio Nirvana 300B SET = 2.7 ohm, DF = 3

11' x 12' = 132 sq ft = 12.3 sq meters

At the Cube Audio website we find these recommendations:
Nenuphar Basis -- 25-100 sq m
Nenuphar 10" -- 20-40 sq m
Nenuphar Monitor 10" -- 12-25 sq m <====
Nenuphar Mini Basis 8" -- 20-60 sq m
Nenuphar Mini 8" -- 12-25 sq m <====
Nenuphar Mini Monitor 8" -- 12-20 sq m <====
Magus 8" -- 15-30 sq m
Bliss C 8" -- 15-30 sq m

I’m also looking into the Boenicke which I am hoping to demo soon. 

Well, you can't go wrong there. My other speakers (in my music room) were a pair of Boenicke W5se. I liked them well enough to upgrade to the W8se. Different styles but both provide a lot of quality and enjoyment. You may have a hard choice.

- Robert
"Parts Connexion listing for the part which is actually a 1 ohm resister not a 100 ohm resistor as the listing states.  Which interestingly enough brings the damping factor to 8."

I assume the two resistances (the speaker at 8ohm and the 1ohm added) are in parallel. Thus the total resistance would be related to the inverses.

1/8 + 1/1 = 1.125

1/1.125 = 0.889 ohms seen by the amplifier. The lower resistance makes for a lower damping factor (by a factor of 9 or so) which would be why Vinnie recommended adding the resistors.

Note: I am not a EE and I don't play one on TV.
"Looks like the amps with 2a3 tubes are 2.5 watts/channel. Is that enough to hear at sane listening level, assuming you sit 8-9ft from the speaker?"

For my "sane" levels it would be, but it also depends upon the size of your room. 20-40 sq meters is 215 to 430 square feet (20' x 20').

From the Cube Audio website:
"The Nenuphars are dedicated for rooms of 20 - 40 square meters. They are a perfect match for a tube amp with at least 3 Watts per channel. Our personal preference is somewhere around 2A3, Px4, 45 tube-based amps. Nonetheless, most solid-state amps (especially those working in A-class) are also an amazing match for the Nenuphars."
"I found independent power supplies for each channel to be a very substantial upgrade when I did it for my first watt f4s. I think I've said this before too, but it's a really beautiful amp that doesn't get the attention it serves, btw."

I remember reading the 6moons review of the F-4 years ago and thinking they would be perfect if one had a preamp that they loved.

- Robert
EnjoyTheMusic has a short news item on Aries Cerat and their new Ianus series of electronics:

Aries Cerat Ianus Series amplifiers is a showcase of the company's unique TriodeFet technology. After years of developing and refining their technologies, they are proud to introduce the TriodeFet technology, and a Series of amplifiers that implements this truly innovative technology. This technology is neither a hybrid topology (in the usual sense of a tube-driving solid-state stage type), nor a solid-state driving tube kind of stage. TriodeFet is a new way of using hollow and solid-state devices. The concept is to have a low voltage / high current active device, which had the linearity of a triode, and at same time would be able to source enough current to drive low impedance loads directly.

The TriodeFet, can be seen as a three terminal active element, just like a MOSFET or a triode. The company's breakthrough is that its transfer curves are identical of a true high quality triode, with the only differentiator from a true triode is that, the Y-axis (current) is in scaled in Amperes and not mA. What this means, is that you can design circuits that were never before possible either by using tubes or transistors. This new active element can be used to develop simple, very linear circuits, which are stable down to very low impedances, while the TriodeFet's inherent linearity is making the use of the problematic negative feedback redundant. New models within the Ianus Series include the Geminae (€110,000) Class A amplifier that produces 130 Watts @ 8 Ohm. Aries Cerat's Essentia (€39,000) is the little brother that produces 40 Watts @ 8 Ohms.

The Aries Cerat website has a News section:

Be sure to scroll down, look at the show pictures and check out the speaker drivers....
be, what preamp(s) are you using with the SIT-3?

- Robert
"I bought my SIT-1 Mono's (Demo's) for about $500 more than what the SIT-3 goes for new."

That sounds like a great deal. Didn't they sell for $11K when new?
Over on AudioShark I came across an interesting post about Nenuphars and the Gryphon Diablo 300:
Yesterday my friend brought all his system to my home. He wanted to know why i m so happy with my new speakers, Cube Audio Nenuphars.
Full range, single driver, no crossover 6 ohm and 92db.

His system consists of: 
PC from True Signal, SC Sablon t.o.r, IC Atlas Mavros
PC for gryphon: Sablon t.o.r.

I drive my speaker with mbl c51, 300w class D.

Guess what? Gryphon is an amazing match to these moderately sensible speakers! My friend was speechless, anticipating a bad match! I guess Gryphon, when used at low volume, throws class A only power, and that's what these babies like the most.
Wood veneers would be interesting. The black can be a bit hulking, kind of like a Carnac stone in your living room. :-)

- Robert
If one had two SIT-3s could you turn them both on and run the right channel from your preamp to one and the left channel through the other amp? One amp would then drive the right speaker and one the left.
Speaking of Tektron tube amps, they are the 2a3 amps used by Cube Audio at shows. Robyatt Audio carries four of their smaller amps/preamps.
I may purchase one this winter to check it out.

- Robert
Preamps are sometimes under-appreciated, with more time being focused on amps and speakers. It may have been Robert Harley who wrote that the amplifier determines the character of a system while the preamplifier determines the quality.

- Robert
<<For those who are using SIT-3, what preamp are you using?>>

My Backert preamp uses two 12au7 tubes. Tube rolling is highly recommended. This evening I replace the stock JJs with Mullards. Amazing.

"My father's house has many rooms..."
If you want to stay with your FirstWatt amplifier, I have had excellent results with a tube preamp from Backert. All of their models have very long tube life and are very easy to tube roll (I recommend the Mullard 12au7).

As for an earlier question about speaker cables, I've had good results with my Stealth Audio pair, although I admit I haven't tried anything else.

Speaking of DF, a couple of weeks ago I was cruising the intranets reading about damping factors and came across an article by a couple of guys who put together PA systems (which explains why they talk about speaker cable lengths of 50 and 100 feet).

At any rate, they noted that the DF decreases with longer speaker cables so I may try 8' versus 16' speaker runs. They provided some numbers:

50'    12AWG   8ohm   DF= 49.1
50'    12           4                  24.5
50'    12           2                  12.3
100'  12           8                  24.9
100'  12           4                  12.2
100'  14           4                    7.9
100'  16           4                    4.9
It's a rainy morning here in Wisconsin so I thought I'd write some about my Nenuphar journey. Two or three years ago I decided to build a system around high efficiency speakers in order to see what people were talking about. I ended up with the Teresonic Magus monitors and the LTA Z10 integrated amp. A nice combination.

Then at AXPONA last year (seems like a very long time ago) there were two rooms that made big impressions. One was a Goldmund system where notes just hung in the air. However, it ran well into six figures. :-(

The other room featured Nenuphar speakers by Cube Audio. The music was liquid and (to steal a line from Joni Mitchell) stuck to all my senses. So, earlier this year I finally put in an order for a pair of Nenuphar monitors. I decided on the baby Nens, the Mini Monitors. Jon at Refined Audio had one pair in stock.

Although they have the 8" drivers and are only 10" x 14" x 24" high they proved plenty loud enough for my 20' x 14' living room. Not that I listen at head-banger levels. The supplied stands put them a little high for me (I tend to sit low) so they ended up on maple butcher blocks topped with IsoAcoutics Apertas.

To be continued....
Nenuphar journey, part 2.

My new Nenuphar Mini Monitors sounded alright after setup, but as my mother used to say, they "didn't send me anyplace I couldn't get back from." Break-in time. As they were I my living room I couldn't just crank them up and let them play 24 hours a day. I took awhile; the sound improved after about 50 hours, and the magic happened at 95 hours.

Now it was time to match the speakers with electronics. I decided to concentrate on amplifiers, adding a preamp later. I had two DACs available, one with volume control and one without, so I started with the direct from DAC to amp configuration. The DAC used was the MSB IV. Then it was on to explore my passel of FirstWatt amps, all designed by Nelson Pass and one even built by the master himself.

To be continued....
This week Jeff Day at Positive Feedback has a review of the Pass XP-12 preamp. He starts by writing:
"I have been looking forward to telling you about the Pass Labs XP-12 line-level preamplifier, as I've found the XP-12 to make for an excellent match to the Pass Labs XA25 Class A stereo amplifier as well the First Watt SIT-3 single-ended stereo amplifier which are my current benchmarks for relatively affordable, lower-powered (25 watts and 18 watts, respectively) high-performance, solid-state stereo power amplifiers."
In this month's TAS (October 2020) Jonathan Valin reviewed the Børresen 05 loudspeaker. In the course of the long review he discussed sound staging.

"I’m not sure I have ever before heard clearer, tighter mono focus than that delivered by the Børresen 05s. I’m not talking about vertically “slit-like” imaging here, as if the vocalist has been turned into a narrow slice of peach pie. London’s voice, for example, is life-sized, rounded, and quasi-dimensional—not slightly one-dimensional as she would be through most cones-in-a-box or as fully 3-D as she is through the MBLs—but it is also unusually 'fixed,' solid and stable and centered right between the speakers....

"I used to wonder why Michael and Lars always widely spaced their speakers (nearly wall-to-wall) at shows, and then toed them in dramatically. (The folks at Audio Physic used to do this same thing.) But it is clear to me now that, because of their speakers’ more focused, phase-coherent release of energy and their low-reflection, low-diffusion enclosures, Borresen and Kristensen were using the space between the speakers to 'imply' greater stage width."
Initially I had my Cubes pointed straight ahead but have found they do sound better with a slight toe-in. Haven't tried corner placement because of furniture constraints.

Boenickes and Cubes are quite different animals but share something that I find attractive. It might be called flow or a more natural sound. I don't care for speakers that "push" music at me.
Speaking of the resistor solution, Stephen, could you elucidate more? Were they across the terminals? Were they at the amp or the speaker? Are they in series or parallel?

Series vs. parallel.

If the only link between the amp the speaker is through the resistor and then to the cable, then it would be in series.
If the resistor makes a looping connection in addition to the regular cable connection, then it would be in parallel.

It is still not clear to me which Vinnie suggested.
Nenuphar journey, part 4.

The next amp to listen to with the Nenuphars was the FirstWatt F-1. The F1 was the first model of the then new First Watt enterprise. The amp in my living room was serial number 017, put together by the master himself at home.

The general idea with amplifier damping factors is that the Cubes can be overdamped so that lower is better. And the most obvious 'better' with low DF is more bass. The F-1 is probably unique in that its output impedance is a whopping 80 ohms. Since the DF is calculated by dividing the speaker impedance by the amplifier output impedance, for the Nenuphar and F1 combo we have 8/80 = 0.1....Yowza!

Well, yes. It seems the F1 is a bass beast. Too much so for this boy when listening to Yellow's Toy album, but great with the growling intro to Biloxi (off The River & The Thread album by Rosanne Cash).

If anything, there was a bit of bass overhang, probably from too low a DF. There was a touch of sibilance on Joni Mitchell's A Case of You. The soundstage was average/normal for my setup.

Next up, the SIT-3
Nenuphar journey, part 5

The next amp to be paired with my Mini Monitors was to be the SIT-3, which needs no introduction here. I had heard the combo at AXPONA, so that when I unexpectedly acquired a SIT-2 from a fellow in Hawaii the new boy jumped to the front of the line.

The SIT-2 made for an overall more refined sound than the previous amps. It was mid-centric which accounts for the 'tube-like' descriptions found in some reviews. There was a large soundstage and the presentation was more forward -- Sinatra had moved to the front of the stage. Lots of bass and no problems listening to beat-heavy music. Beck had swirling swashes of sound, sufficiently psychedelic. Who knew 10 (or 12) watts could make this much music?

It made one wonder what a pair of SIT-1s would sound like (the SIT2 is basically the stereo version of the 1s).

To be continued....
David, very nice review in Stereo Times. Are you the 'Davis' mentioned in the article?