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

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

rwpollock
Look forward to hearing more!

I think the focus on DF is going overboard - circuit is more important. @213Cobra recently told me he believes the Ampzilla 2000, 2nd Edition is the best SS amp he’s heard on Zu Audio speakers which have similar driver characteristics to the Cubes. I was very surprised to hear this (and between him and I, we’ve owned/heard the SIT-1, 2, and 3, and 20+ other P/P and SET amps on them). My personal favorite amp on Zu is Quad ii Jubilees - which also use some negative feedback. I wouldn’t get too tripped up on DF being the decisive factor. Also, Srajan listens at 60db volume levels which is very unusual. For contrast, I want to hear the Tron (reboot by Daft Punk) soundtrack at 90dbs to test amp flexibility.

As far as trying the Nenuphar myself, I reached out to Jon and he was hoping to have stock at the end of the month. There are no places in SoCal to hear them, but he offers a generous 60-day return policy. I’m also looking into the Boenicke which I am hoping to demo soon.

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

Keith,
I don’t believe that anyone is going overboard in regard to the damping factor (DF) variable . The Nenuphar manufacturer himself has clearly and often discussed the inherent damping of the unique driver. He has explicitly stated the driver is purposefully designed to be used preferably with high output impedance amplifiers with little or no NFB and thus a low DF. Stephen unequivocally hears an improved sound quality with the substantial lowering of the DF of his Vinnie Rossi hybrid amplifier.

No here is disputing that low output impedance amplifiers with higher DF can sound quite well driving the Nenuphar. In fact this point has been stated in this thread on more than a few occasions . Gryphon, Bakoon and Mola Mola as a few cited examples. I believe that folks on this thread recognize that Df is just ’one’ aspect but nonetheless a relevant one.

Stephen’s recent positive experience of lowering the DF did naturally raise curiosity as to how one simple resistor could achieve this. Thanks to Stephen’s email response from Vinnie Rossi explains it for us. I and I believe most of the participants on this thread seek further education on technical matters that so obviously impact sound quality.

I don’t find Srajan Ebaen’s listening levels to be an impediment to providing meaningful reviews. BTW I’ve had limited exposure to the Swiss Boenicke and I think they sound exceptionally good.
Charles