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.
Ag insider logo xs@2xdavid_ten
Hi debjit_g,
DF=Speaker impedance (In ohms) ÷amplifier output impedance. 
So to lower the DF either the amp output impedance must increase (Denominator) or the nominal speaker impedance is decreased (Numerator). Unless there's something I'm missing. With amplifier specifications the lower the output impedance the higher the amp's DF. This usually reflects the amount of NFB employed in the circuit. 
Obviously a positive outcome regardless of the reason, but this discussion just makes me more confused. In the numbers posted above, doubling load resistance doubles dampening factor while VR indicates that adding 1 ohm to the load cuts damping but a factor of 10??

Does anyone know what might differentiate between a resistor changing output impedance vs changing amplifier load?  As I see it, this alters how much resistance is in the post-amplification circuit. Good that it worked, but color me confused.
Yes I wondered the same in terms of the exponential (10x)  change in the DF value with just a simple resistor addition. I'm surprised that its of such magnitude. But in practical terms the sound quality did improve. 
"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.