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

@david_ten Thanks for posting!  Interesting that he comes to a different conclusion about preferring the 10" driver over the 8" (vs. Jon @ Refined Audio and some of the posters here).

@grannyring Bill, are you thinking about buying a full commercial unit, or building your own using the drivers? 

@khragon Thanks for posting.  It's crazy how people just black & white every product evaluation when it always depends on the system.  Glad you got to try the speakers with an appropriate amplifier to see what they do...

Congrats Stephen.  That's great to hear.  And I know it's not a diy-heavy crowd, but if people find a SIT-2 and want to convert it into a SIT-1, I believe there are only two core differences... separate power supplies for the monos, and the adjustable aspect of the 2nd harmonic on the SIT-1s.  In the end, a SIT2 with one channel broken out into its own chassis and with its own power supply will probably get you most of the way there.  Anyone who's built a DIY first watt amp could easily make the conversion.  I've found a huge impact of adding a separate power supply for each channel.  I'll never go back to a stereo amp again.

Please keep us updated on the journey Stephen.

@charles1dad Would be fun to combine the best of both worlds with four Cube subwoofers!

Fun descriptions. Thanks for the elaboration

Great information folks.  And super useful to see the list @david_ten. 

Thanks.

@jollytinker Looks like there was a typo in your 6moons link. Here's the corrected one: http://6moons.com/audioreview_articles/thoress2/

@rwpollock Obviously it's *best* to just let the speaker designer make all the decisions for you, but there are a lot of subwoofer options out there that have all the basic features of the BASiS subs.  The full range driver is indeed "rocket science-ish", but looking at the subs makes me think there are plenty of other more cost effective solutions that might work just fine. 

The pandemic has hit almost all of us, so I'm also on long delay, but I'm still thinking about building the sealed box diy version of their monitors and pairing with my existing subs (the 2 x 12" bass units of Coincident PREs) and subwoofer amplifiers (Dayton audio SA1000 monoblocks). Won't look as pretty and may not sound quite as good, but it should be close at the worst.

It would be interesting to try the sit3 in a dual mono configuration for a more fair comparison to the sit1. All you need is a second chassis, power supply, and then you just move one channel over. Anyone over on the pass labs forum of diyaudio could do it. As I've mentioned earlier in the thread, 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.

@rwpollock Definitely.  The idling board of the unused channel does (in my experience) still create a little extra distortion though, so if I settled on that solution, I'd eventually disconnect that board from the power supply. If a friend had a unit, your method would be the easiest way to see what the benefit would be.

Thanks for the heads up David.  The 1 cubic foot sealed box DIY version will be my next audio journey and it's good to see the thread staying alive. Really looking forward to the building experience. Curious if I'll be able to pull off a high gloss black piano paint job.

@rwpollock Not an answer to your question, and it's been stated earlier in the thread, but just keep in mind that adjustable damping factor and adjustable levels of negative feedback are (always?) synonyms. Might be useful for expanding your amp search if you've been looking for amps with adjustable df... 

I just ran into the damping factor thread and see the above comment was completely unnecessary. Sorry Robert.

@stephendunn There are certainly posters out there who's ears I trust that use and enjoy digital correction.

Unfortunately my only experience was *not* good. I had a Lyngdorf tdai-3400 for some time and turning on room perfect kind of made me sick to my stomach... the music sounded "blended" for lack of a better term. Definitely less natural than without.  I had the amp for about 6 months, so I knew it well and had obviously done RP setup many, many times. Just couldn't get it to sound right with my Coincident PREs. Every time I turned off any form of digital processing it got better actually, but never quite right.

Very curious to hear about your experience and add another data point.

For future readers: In case the above link expires, please note that the link text is somewhat misleading. It is for a 1ohm 10w Jantzen Audio Superes resistor.

And @stephendunn, congrats on the outcome. And good information. I didn't know that a 1 ohm resistor in series with a driver had this effect. Apparently I need to learn more about damping factor calculation and meaning...

Since many people in here are considering the bakoon 13r, I thought I'd quote a post from @almarg on the input impedance:

"Re the Bakoon 13R, be aware that the input impedance of its RCA input is only 10K, which will not be a good match for many and perhaps most tube-based components.

I believe the other input choice provided by the 13R, a "Satri Link," would only be usable if driven by a Bakoon component providing that kind of output.

Regards,
-- Al"

Although I know RIAA's above comment is in jest, just to be clear for future readers... If you don't follow the 1/10th ratio rule, you will not get a flat amplification of the preamp signal with frequency aberrations in the bass response.

Also, it may be possible to modify the amplifier to address this issue (depending on amplifier design). My first watt f4s (simple class A without feedback) have a 47.5k input impedance, but can be modified to have a higher I.I. simply by changing out the resistor on the input.  I was informed that I could use anything up to 250k without changing the operation/sound of the amp. Doing so enabled me to use much smaller output caps on my Don Sachs 6sn7 preamp, and allowed me to afford some top end duelund's that greatly improved the sound. No idea if this is possible on the bakoon... but hopefully useful information regardless.

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.

@fjn04 You have to go to the driver pages for cube audio to see the full specs. Here they are for the 10" neo used in the Nens:

Thiele / Small parameters
Fs = 30 Hz
Re = 5.5 ohms
Le = 0.006 m
HQt = 0.43
Qes = 0.44
Qms = 17.8
Cms = 0.76 mm/N
Vas = 127 liters
Sd= 346 cm^2
Bl = 9.7 Tm
Xmax = +- 3 mm*
Xdamage = +- 6 mm
Sensitivity = 92 dB
Impedance = 6 Ohms
* Voice coil remains in 100% of magnetic field.

And since everyone should love their preamp...

@rwpollock Wow, had seen the name in print, but didn't known anything about those amps. They look like a ton of fun.

A question to those of you who have been thinking about these speakers for a while. If you're supplementing with subs, is there any reason to choose cube's 10" drivers over the 8" ones?  

@toetapaudio  Thanks for the information.  If I went this direction, I'd start by just buying the driver.  Was thinking that I'd probably start with open baffle in that case and potentially copy Nelson Pass' approach ( https://www.stereophile.com/content/gramophone-dreams-26-nelson-pass-harmonic-distortion-page-2), or use the Cube drivers to replace the head units on my Coincident PREs (again in an open baffle).  I'm assuming that the drivers in free air would start dropping off substantially higher than the enclosed 30hz.  And given that I listen to quite a bit of electronica with some rap, pop, and hip-hop, I'd need to add in those lower octaves.  Essentially, that would be a diy version of the BASiS.

@david_ten Thanks David.  I think I'm still a year or so out from going this direction, but have been trying to learn a lot about full range drivers to figure out what I might build.  I've also been looking at the Audio Nirvana drivers, but I know Nelson Pass has tried them (and many, many more), and apparently he's showing off the Cubes.  

I don't know what to think about recorded speakers playing through youtube over laptop speakers (or earbuds), but I watched that video and was also impressed.  As you point out, at least if everything is the same except for the speakers, the comparisons should offer some information.  And you certainly can't argue with Peter's subjective reaction...

Also, I've heard this system in person ( https://www.avshowrooms.com/aaudio_imports.html) and do feel like I picked up some of its core essence even via the youtube/computer interface.

Just as a data point for folks.  I reached out to Jon at Refined Audio and he noted that he had a *slight* preference for the presentation of the 8" neo driver over the 10" one.  And also that it sounds great in a 1 cubic foot sealed box.

@jmolsberg If you're willing to DIY, the entry price isn't as bad as it seems.  Jon @ refined audio was recommending a simple 1 cubic foot sealed box with the 8" driver if you're going to augment with a sub system.  Cube audio has a lower model featuring the same basic technology (the Fc8 Driver) for $1500/pair.  The new 8" neo drivers from their top end models go for $4700/pair.  Still expensive, but reachable for more people...

And @stephendunn  Wow, congrats.  Sounds like the most positive early impressions you could possibly expect.  Great to hear, and makes me even more interested in trying out these drivers. 

@khragon  Congrats!  Please do report back on your experience...

Since we’re talking about first watt amplifiers that may provide a good match, I’d just like to mention that the F4 doesn’t get enough attention.

25 watts, zero negative feedback, and no gain stage to modify the sound of your source and preamp, all it does is provide current. A very simple circuit. If you’ve got quality upstream components and enough voltage from your pre/source, it is just fabulous. On my Coincident PREs, it beat a diy sit3, pass labs xa25, atma-sphere m60s, a lyngdorf tdai-3400, and Coincident Frankenstein 300b monos.

In regard to this discussion, it has an output impedance of .2 and a damping factor of 40.

And @khragon, I suspect you’ll still love the speakers with your current amps, even if they’re not the ultimate match. If you happen to be in Colorado, I'd happily bring over the f4 & sit3 for a comparison.

Me too Charles, me too. I would never have believed it if I hadn’t heard it with my own ears. I blame it on the transparency of the f4 paired with a second harmonic distortion character (w almost no 3rd and vanishing amounts of higher order harmonics)...

And, totally agree that the Franks should be just spectacular on the cube audio drivers. Wish I could have afforded to store mine for just such an occasion. As you know, I absolutely adored my pair...

(Incidentally, I just bought some .9999 solid core silver speaker cables based on an old comment of yours that had been rattling around in my head... Just as you said, putting in silver added beautiful, natural refinement to the system with no drawbacks over my previous duelund tinned copper. So happy I remembered reading the suggestion from years ago. I already had Occelia silver interconnects based on your recommendations, but am planning to rewire my amp, pre, and speakers to take it all the way through.)

@bobheinatz You can see Nelson's implementation here:  https://www.stereophile.com/content/gramophone-dreams-26-nelson-pass-harmonic-distortion-page-2

And as you may have read above, Jon Ver Halen @ Refined Audio recommended a 1 cubic foot sealed box (with a bass compensation circuit) as his preferred DIY solution... over Nelson's.

@stephendunn  I did the 14ga tempo electric wire.  No marketing, no fancy terminations, just .9999 pure silver in an oversized teflon jacket (so that the wire is mostly just floating in air for the best dialectic rating possible).  They charge around $200 per meter for stereo pairs and give you a 30-day trial period.  

Basically, no-one's going to give you better raw materials, they're just going to mess with the dialectic (probably for the worse) by changing whatever the wire is embedded in and then change the cable geometry (which will necessitate going from solid core to stranded cables).  While I'm sure things can get better, I suspect it's going to cost you $1000s to find out. 

I've also experienced success with VH Audio's .99999 solid core silver in cotton for a DIY interconnect, and Ocellia's silver reference interconnects, which I bought on the recommendation of @charles1dad . In all cases, the silver was better than the copper I had in before.  

@abd1 This won't help with bass frequencies, but if you're wondering about the impact of your cutout, one useful technique can be to carry around a bluetooth speaker (obviously the closer to full range the better) and listen to how the sound changes as you move it into that space.  That can give you a sense of what frequencies are being altered by the reflected sound from your main speakers. (Note, this is also useful for testing room treatments like absorbers and diffusers).

Still haven’t built my pair, but I’d like to take another opportunity to suggest the tempo Electric solid core 99.99% silver in oversized Teflon jackets. That’s basically the purist, most conductive wire available in one of the lowest dialectic insulators. Other people may appropriately charge you for advanced geometry and terminations, but they’re not going to beat those basics no matter the price.

I replaced all the wire in my system with high purity solid core silver including all internal wire in my Coincident PRE speakers. Every step of the way things got more natural and refined. The tempo Electric wire runs all the way from my internal amplifier boards out to the speaker drivers. Not a touch of the brightness or thinness sometimes associated with silver.

@keithr Hopefully someone who's actually done the comparison will step in, but I suspect these two designs will sound very different. You can likely catch some of that if the read the two corresponding 6moons reviews and compare some if the descriptors used across across them...

E.g.:
See paragraph 3 here - http://www.6moons.com/audioreviews2/zu3/6.html
And whole page, but especially final paragraph here - https://www.6moons.com/audioreviews2/cubeaudio2/5.html

@debjit_g After four years of work getting my Coincidents to finally sound like a reference, I'm not feeling a big rush to try new speakers, but I still like the idea of putting the neo driver in a 1cuft sealed cube for a diy project and change of pace. I'm very attracted to the idea of eliminating the crossover. If I do take the plunge, I will most certainly use the tempo Electric wire inside the cabinet. Would probably go with 14ga as that's what I currently use on my mid-range driver (20ga to my tweeter & 12ga in the bass cabs).

~~~~~

And @charles1dad I wonder if Israel's stated preference stems from the fact that he sells his own copper wiring. Replacing the stranded copper (with a Teflon jacket) in my PREs with solid core silver reduced distortion, and increased texture, color, and naturalness. As you stated, the silver sounds smooth with a subtle warmth. I don't hear any tradeoffs at all. The only downside is increased cost.  I'm confident anyone with these speakers who did an a/b would prefer it.

And I don't blame you for leaving well enough alone inside the Coincident electronics. I've been using VH Audio's silver (5N, solid core) inside my electronics, but also still have a lot of copper in the various circuit boards. Routing new signal wire throughout all the pTp wiring would certainly be a laborious project. And as you state, they already sound so good...

~~~~~

Also, for anyone considering the option, Tempo Electric's 14ga is only ~$60/meter (x4 if you're buying a stereo set) with a 30-day free trial. It's a bargain.

@stephendunn Congrats on the outcome. I’d also be interested in how the SIT-1s would sound driven by a high quality tube (6sn7 or dht) preamp (perhaps you’ve already tried this?). I love Pass labs, but have read some mixed reviews of their preamps and wonder how much of what you’re hearing is from the preamp stage of the VR.

(Edit, I just looked up the VR and see they talk extensively about the - dht- tube typology used in the preamp gain stage!)

(Edit 2, and now I see the VR has a preamp output so you can actually try running the SITs with the VR front-end and see exactly how much you like each of its parts. That's great.)

Four pathways that will in combination fully demarcate the contributions of each preamp and amplifier. Sounds super informative. And wonderful music in all cases no doubt. Looking forward to reading about the outcomes... 

I've been researching dht preamps and am really looking forward to the report Stephen. Not sure it'll have enough gain to drive my F4s, but the VR preamp really looks great.

Btw, I just wanted to say how exemplary this thread is. Just pure, helpful, experience sharing and education. It's really a pleasure, thanks. If only the rest of the site could follow suit...

@jollytinker Ha. You just gave me flashbacks to having my soldering iron pulled out of my hand by the magnets on my accuton drivers.  Fortunately just to the magnet and not towards the driver.  Super fun times!

Yes, those were my amps

And a new rivalry was born... 

Joking, btw...

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.  

@stephendunn I also have my system set up on a room corner (see my system pictures). Forced by the room in my case, but it works really well. Eliminates the usual side wall reflection issues and allows for a deep space between the speakers as if they were pulled out much further into the room. I much prefer it to the long wall setups I've been forced into in the past.

@toetapaudio No pressure, but I personally think a pros/cons list would be useful here too.  Seems relevant given that this thread is more of a place (one of the only ones) to generally get information about the cube audio experience...

@stephendunn Thanks for the additional information regarding resistor setup, much appreciated.

That would actually be a series connection. In parallel circuits, electricity is flowing through two independent circuits. If either is cut, the other circuit will be still be conducting electricity (think modern Christmas lights where breaks in the circuit, i.e. a burned out bulb, don't cut out the whole stand). Alternatively, in a series circuit, each component is an integral part of the circuit and if it breaks, no electricity flows (i.e, old Christmas light strands where every bulb needed to be tested to find the fault).

In this case your amp is producing electricity and the positive & negative wires complete that circuit and allow it to flow through the speaker. If the resistor were connected in parallel to that circuit, it would be connected to both the positive and negative terminals of the amp (or speaker). Cut one leg of the resistor and the full speaker circuit is still connected to both terminals, electricity flows, and the music continues.  Instead, you've got it connected in series with the speaker circuit. Cut one leg of the resistor and it breaks the circuit and there's no connection/electricity/music.

I believe in quality parts, monoblocks, and overbuilt power supplies, but also simple, well-known circuits without negative feedback that can be implemented cheaply. Most of those set circuits were fully detailed/explored decades ago and modern flagships are just very careful/thoughtful instantiations. All that's to say that you may find your little tekton hanging right along with much more expensive offerings.