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

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

- RWP

Too bad Pass Labs can't develop another source for static induction transistor devices.

   I suspect they could have their own made, but it wouldn't be cheap. It sounds like that is what Aries Cerat did. This summer EnjoyTheMusic had a short new item on Aries Cerat and their new Ianus series of electronics.
www.enjoythemusic.com/news/0720/

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.

Correct. It's not my field, but I wouldn't be surprised if there aren't chip foundries that will do custom work and small runs. Not cheap, but perhaps Pass could buy a passel from Aries Cerat or have their supplier make a different version.

Question for Stephen:
IIRC, the Vinnie Rossi integrated has a pre-out. Did you listen to the DHT preamp feeding your SIT amps? 

- Robert

Continuing my explorations of tube amplifiers with the Nenuphars, I purchased a David Berning ZH-230 amp from Rick at Hi-Fi One in California. A splendid amp and a good match with the Cubes. A couple of years ago I had used an LTA L10 integrated which is also a ZOTL design. As my mother used to say, it didn't send me anywhere I couldn't get back from.

The Berning amp, however, is like drinking spring water. It has the detail of the Bakoon/Enleum amps but without any sharpness. Definitely recommended for an audition if you get the chance.

Interesting enough, Rick also sent along a passive preamp that he and Steve McCormack had put together some years ago. Surprisingly (to me) it is a very good combination -- that transparency thing.

- Robert

Re the different solid state amps:
I wanted to note that the main difference for me was that the FirstWatt amps had a bit more of the mid-range-icity that is a major attraction of tube SETs.

Robert

"I am curious how the L2iSE would stack up against some of the better lower watt SETs out there but none have found their way through my door. "

I'm thinking that would be a good project for this winter....
Currently I am trying different tubes in the preamp section.
Robert

Well, I've followed stephendunn down the Vinnie Rossi integrated path. Definitely recommended.

Here is my ranking of the amps I have used with my Nens:
Vinnie Rossie L2i-SE
FirstWatt SIT-2
FirstWatt SIT-3
Bakoon 13-R
LTA Z10

"Could you elaborate please on your particular set up for evaluating these amps, the make of preamp and/or dac used with the First Watt amps and dac if any with the Bakoon and LTA? Do you use the VR with its dac board?"

The source is an Aurender N10 paired with a Holo Audio Spring DAC (Level 3) or a COS D1. With the power amps I used a Backert tube preamp, the original Rhythm. The 12au7 tubes were upgraded with NOS Mullards.

I found that I preferred some tubes in the signal path. The SIT-2 and SIT-3 were very close when used directly with the COS (no preamp). To these ears the SIT-2 improved more when the Backert was added to the chain. I could easily live with either of the FirstWatt amps or the Bakoon, but the LTA lacked some musical magic. I never did get entirely comfortable with the volume control on the Bakoon.

Robert

My first comparison was between the Electro Harmonix 300b that came with the amp and an EH 2a3 set. I preferred the 2a3 as the 300b tubes were 'slower' even though they had a richer sound. That trade-off was solver with a set of Takatsuki 300b -- the best of both worlds and my current favorite. I do have some KR Audio T-100 DHT on order. I will keep you posted.

In the meantime, I have tried some NOS tubes: 71A and 112a (Most the old tubes seem to run at 5V). The 71A were a bit lean, but the 112a Cunninghams are now in second place after the (pricey) Takas.

Fun days and an embarrassment of riches....

Robert
 

"It’s interesting and surprising that we don’t have mention of 300B - Nenuphar pairings."

For whatever reasons, this thread got started with a focus on solid state amplifiers and has discussed/explored tube amps only minimally. I suspect it is because Jon Ver Halen at Refined Audio (the first Cube Audio distributor in the US) uses First Watt amplifiers.

Robert

I did ask Jon why he didn't use tube amps. He smiled and said he was good friends with Nelson Pass....

Jon also used Pass/FirstWatt amps and preamps back in his Lowther America days.

Robert

Another data point in our continuing, vaguely perverse, search for solid state amps that play well with Nenuphars -- SPEC RSA-M3EX from Japan (the EX stands for export model). Jeff Day at Positive Feedback wrote a lengthy review back in 2015 with the backstory. Mr. Yazaki and his friends wanted to re-create the sound of the classic post-WW2 amplifiers.
https://positive-feedback.com/Issue78/spec_realsound.htm

Well, they succeeded. There was one for sale on Audio Mart back in August and have been enjoying it since. The amp isn't about that bump in the upper mid-bass; the focus is on tone. Instead of listening with my forebrain I find myself listening a little deeper. Turn off your mind, relax and float downstream.

Originally I paired the SPEC with my Boenicke W8 speakers as they appreciate Class D amplification as Sven himself uses. It made for an ambiance-rich pairing. Paired with my Nenuphars, the SPEC was in the upper echelon, keeping company with my SIT-2 and Vinnie Rossie integrated. While the SPEC is an integrated amp it has a preamp bypass switch so you can mix with your favorite preamp flavors. Currently I am listening using the excellent icOn passive pre.

So, if you get a chance to catch the RSA-M3 it is recommended.

Robert

"Funny, I was talking about SPEC CORP the other day with the U.K. dealer friend of mine and he rated them."

Rated or hated?

Some might find the SPEC to not be incisive enough. If so, that can be cured by pairing it with your favorite preamp....

DB2

<<I thought it would be interesting to know what speaker cables you are liking with the Nenuphar’s?>>

I've used three types. In order of preference:
Ansuz
LessLoss
Stealth
Of course the amplifier plays a significant role as well.

 - Robert

Re the Ansuz cables, I have a set of D1 which, given the improvements from the 1 generation to the 2 generation, may be equivalent to the C2 level. Agreed that their power products are the place to go; I bought their other wires in a package deal I couldn't refuse from someone who was upgrading at the time.

At a lower price point I would certainly recommend the LessLoss products; Atelier 13 in Nashville offers a loaner two-week home trial. The package contains an assortment, but once again power is the ruler.

- Robert

As I mentioned upthread, my class D SPEC amp is now driving my Boenicke W8 speakers. It was now time to explore tube amplification (fronted by Vinnie Rossie DHT using Takatsuki 300B tubes).

Where to start? As I looked at listing on Audigon and Audio Mart my thought was to go with something that had solid resale value. Also an amp in the (for me) mid price range. I didn't want to do the upgrade two-step too many times.

Well, brothers, I'm here to tell you I've seen the light. A bright green pleasure machine. Yes, Shindo has captured my heart. The little Cortese F2A -- 10 watts and 15 pounds. Texture and liquidity. Plenty of bass. And, as one writer put it, it just sounds as if the band was better rehearsed.

Will I sell my SIT-2? Not now, but maybe down the line....

- Robert

FWIW, Art Dudley's review is about the newer Cortese. The one I have is an older model designed by Shindo pere, Ken. There is a review and picture here at Dagogo:
www.dagogo.com/shindo-cortese-f2a-tube-amplifier-review/
Does anyone know how they differ?

Just thinking about the joys of listening to music with a great rig. Like others here, music is my drug of choice. Last month I did a road trip to San Antonio. While I didn't actively miss my music for those weeks upon return I found myself listening for hours more than usual....

This past winter I've been listening to my Nens with a couple of tube amps. As expected, both made for a good pairing. The Shindo Cortese had better tone while a 300B SET from AricAudio had more palpability. Preceding the amps was either the preamp stage of Vinnie Rossi's L2i SE or the icOn4 passive.

 - Robert

Charles, yes, an embarrassment of riches.

As for the tube brands, Aric included in the sale both Psvanes and Elrogs. I prefer the Elrogs and am feeling no particular rush to try other tubes. However, comments here have me wanting to listen to the new Enleum. (I did prefer tubes to the Bakoon.)

 - Robert

"Next: both tone and palpability.... a Shindo-Aric cross. :-)"

 

Any suggestions?

"I am in the camp of keeping what you currently have."

 

Charles, agreed. I don't have a burning itch (is that a mixed metaphor?) that needs to be satisfied with new/different equipment. In that sense I have slowed down over the years. My question was more from curiosity. If someone wrote that brand XX or a vintage YY manages to get a bit more of 'everything' then I would keep my ears open at AXPONA or Audiogon.

 

Of course the price for converging perfection tends to increase exponentially. For example, I have followed Vinnie Rossi since his Tri-Path days, but his new line is a bridge too far for me. The new Brama preamp goes for $35,000 and weighs near 100 pounds!

 

That said, I know I am very fortunate to be able to have, not one, but two great sounding systems. And I have always been a bit eclectic in my tastes....

And I much preferred the 2019 Refined Audio room to their room this year.

Different setup perhaps? They weren't using a SIT-3 this year.

<<Robert, has your move to tubes (Shindo and Aric Audio, etc.) changed your perspective on what's 'musically' achievable with the Nenuphars in the system chain?>>

 

Surprisingly to me, no. I have learned that the Nenuphars are sensitive to the quality of what's upstream, but then it comes down to personal preferences. Perhaps not unlike Stephen with his stable of different horses, I can listen quite happily using either a 300b or SIT-2 amp. If I do use the SIT, then I will pair it with a tube preamp. That said, I ended up here because I heard the Nens at AXPONA with an all solid state amplification chain....

I've listed the amp on AudioMart. Check there if you are interested. They're not making any more of them. :-)

<<The V2 drivers, being brand spanking new, are still way tight, lack top end airiness/open-ness and overall dynamics, especially in the treble region, sounding overly polite thus lacking essential sparkle. I am expecting some improvement in these areas as the drivers loosen up and everything settles in...>>

 

My V1s took awhile; the sound improved after about 50 hours, and the magic happened at 95 hours.

A link:

 

Stereophile has a review by Ken Micallef of the 25W Pathos InPol Remix MkII integrated amplifier. The specs caught my eye as the output impedance is listed as 0.9 ohms. As the Nenuphars have an impedance of 8 ohms, this would make the damping factor

8/0.9 = 9

which is pretty low and down in the tube amp range. The SIT-3 has a damping factor of 30.

 

If anybody gets a chance to audition the Pathos please keep us posted.

I recently got a good deal on a used amplifier by Gold Note, the PA-10 ($2K new). It is their introductory power amp and, like the PA-1175, has a switch to change the damping factor to either 250 or 25. Of course I immediately set it to 25 and hooked it up to my Nenuphars.

 

I'm in the tube camp these days, but I'm going to keep the Gold Note as a backup in case my David Berning amp has to go to the shop. I'd rank the PA-10 below the SIT amps but slightly better with the Nens than the Bakoon. It has the usual virtues of solid state -- the bottom end, the detail. Vocals have good presence but lack the palpability of tubes and the floating decays, such as near the end of Scarborough Fair where Garfunkel's "parsley, sage, rosemary and thyme" floats off into the empyrean.

How did it sound with the higher damping factor. Better than expected -- a little drier perhaps and a shallower soundstage.

By the way, word is that Nelson has found a new source of industrial SITs. Apparently they are larger and produce more heat. There is a SIT-4 in the works, but it may be a monoblock configuration to dissipate the heat.