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: 

https://www.cubeaudio.eu/cube-audio-nenuphar

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

https://6moons.com/audioreview_articles/cubeaudio2/

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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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"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.
Stephen said the resistors were added to "each of the positive speaker terminals" which suggests a series connection to me.

Indeed, if it is paralleled with the speaker and connected across both the positive and negative terminals, then it's a very different situation.  I'm not educated enough to know exactly the impact on this amplifier, but I do know that generally amps struggle with the current requirements needed for loads below 2 ohms.  
Agree that if the power amplifier was encountering a speaker impedance of less than 1 ohm (0,89 ohm) this is an enormous challenge for 'any'  amplifier to manage. In fact most amplifiers would be incapatible of delivering the vast amount of current demanded by this low of a speaker impedance. There has to be an alternative explanation.it just doesn't seem as though this usually low speaker impedance if  seen by the Vinnie Rossi amplifier would result in improved sound quality as reported by Stephen. Al (R.I.P.) we miss you.
Charles 
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....
charles1dad & others
According to Vinnie's email below the resistor changed the output impedance of the amp to 1 ohm and did not change the speakers' impedance.  Since the stated output impedance of the L2iSE is 0.1ohm the resistor increased the output impedance by 10 times (about the limit of my math skills).  After adding the resistor I did not notice having to increase volume levels, for what's that worth.  Except that it sounded much better at low volumes, as mentioned before. 

Hi Steve,
Glad it worked!
Can you fix a typo?  It should say 1-ohm resistor (not 100 ohm)
And I meant to say that your damping factor is now 8 (not 80) - sorry!
Speaker impedance / amp output impedance = damping factor.  So 8 ohm / 1 ohm = 8 Enjoy it, and thanks for sharing it!
Vinnie