[Tyson]

Preamble
Had a chance to visit Danny recently and spent a few days listening to ALL the most recent OB offerings and thought I'd write up separate reviews for each of them.  This review is for the NX-Treme.



Initial Impressions
Man, this speaker is TALL.  Taller than my Super 7s.  Taller than the Line Force speakers.  It's right at 7 feet tall!!!  And you all know how I love tall speakers.  Oh, this is gonna be fun.  This uses the same tweeter and midrange setup as the NX-Ottica but it doubles the number of bass woofers. 


Listening Notes
We started with the First Watt BA3 again but we figured it would not be a perfect match after our experience with that amp on the NX-Ottica towers.  We were right - sounded good but not as good as it should have.  So out goes the BA3 and in goes Elekit Japan 300b amp.  Now we are cooking with gas!  All the great things I said about the NX-Ottica applies here, but even more.  World class imaging, bass, dynamics, clarity, power, scale, delicacy, you name it the NX-Treme does it better than just about anything out there.  OK, I know you're going go ask - how does it compare to the Super 7?  I hate to say it but it's a tossup.  Haha, I never, ever thought I'd say that a speaker with a cone based midrange unit could keep up with my beloved planar drivers in the Super 7.  Yet it does.  There's a very slight edge to the Super 7 in ultimate speed and resolution, but the NX-Treme makes up for it with more power in the upper bass and lower midrange.  Danny should be proud, this is an incredible achievement.  I was skeptical that it could keep up with the Super 7 but it does so easily.  Impressive.

And, like the NX-Ottica Towers, even though these are a tower speaker, they really need the servo OB subs for full range sound.  We had the triple OB subs hooked up and they were a perfect match.

Edit to add:  Here is a link to the some impressions that New Record Day had when visiting Danny's recently.  You can hear that there's a tremendous overlap between what I heard and what they heard.  So I'm not crazy!  Haha.

https://www.youtube.com/watch?v=pYP-XErZHu4&t=4s

[maty]

Resized and optimized

[genjamon]

Anybody care to comment/speculate about why the Elekit 300b amp would mate so much better with these and the half-size brothers than the Pass amp?  It sounds like amp matching is pretty important to get the best out of these, so it would be good to know what characteristics are needed. 

Tyson, I'm curious why you brought these amps and not the Dennis Had.  Care to share the reasoning?  And care to speculate about whether this was a general tubes vs. solid state matching effect, or whether there was something particular about your 300b amp that matched especially well?

[maty]

Maybe the First Watt BA3 works right only with 8 Ohms as usual in many DIY class A amps and NX-Treme maybe is true 4 Ohms?

[PDF] http://www.firstwatt.com/pdf/art_ba_3.pdf

https://www.diyaudio.com/forums/pass-labs/258301-ba-3-amplifier-illustrated-build-guide.html

Without NX-Treme graphs...

[Tyson]

Anybody care to comment/speculate about why the Elekit 300b amp would mate so much better with these and the half-size brothers than the Pass amp?  It sounds like amp matching is pretty important to get the best out of these, so it would be good to know what characteristics are needed. 

Tyson, I'm curious why you brought these amps and not the Dennis Had.  Care to share the reasoning?  And care to speculate about whether this was a general tubes vs. solid state matching effect, or whether there was something particular about your 300b amp that matched especially well?

Re: the 300b it just goes to show that you can't really predict how these things are going to go.  I too was very surprised that the BA3 wasn't the best match with the cone based speakers but it WAS the best match with the planar based speakers. 

I brought the 3 amps I did, because they are the ones I rotate around in the upstairs system with the Klipsch, the Dennis Had amps are more or less permanently installed in the downstairs system with the Super 7s.

I think the BA3 is just a warmer sounding amp than the 300b.  So it matched the planars better.

[maty]

First Watt BA3: distortion vs frequency at 1 watt (bottom) and 25 watt (top)

[genjamon]

Ah OK, that makes a bit more sense. I didn’t have the BA3 pegged as warmer than a 300b amp in my mind.

[poseidonsvoice]

Maybe the First Watt BA3 works right only with 8 Ohms as usual in many DIY class A amps and NX-Treme maybe is true 4 Ohms?

[PDF] http://www.firstwatt.com/pdf/art_ba_3.pdf

https://www.diyaudio.com/forums/pass-labs/258301-ba-3-amplifier-illustrated-build-guide.html

Without NX-Treme graphs...

Maty, I'm glad you said 'maybe.'

Here is the thing. Every BA-3 based amplifier build is going to be a little different. BA-3 is just the input stage. It is adapted from the F5 amplifier. The BA-3 then has to be used with an output stage. 2 output stages were designed for the Burning Amplifier series. One is single ended, and the other is complementary (push pull). The single ended version should be used with speakers with nominal impedances of 8 ohms and shouldn't dip below 5 ohms. The complementary version is more amenable to 4 ohm speakers. Moreover, single ended Class A designs are FIXED in Class A permanently. They do not shift to Class AB. The complementary version will shift into Class AB depending on how much bias current is running through the output stage. So the first 20 watts or so may be Class A, and then Class AB afterwards before it clips. Of course high efficiency speakers are strongly recommended since these are First Watt Class A amps and are usually used with +/- 24V supplies. But if you read the document, you can use +/- 32V supplies meaning you can extract even more power. With the graph you posted above, it wasn't clarified whether that was a +/- 24V supply or a +/- 32V supply. Needless to say, the distortion levels are similar for both until you get close to clipping which makes sense. The +/- 24V supply clips sooner.

Sonically, the single ended output stage has a bit more of an ethereal quality, more 2nd order harmonic distortion dominant, while the complementary version is more 3rd order dominant and seems to be preferred for those who prefer more detail.

From what I remember Tyson used a single ended output stage with his BA-3 build. Probably a +/24V supply. And of course, I am sure he upgraded the capacitors, etc...

And we haven't even talked about the power supply designs which will have an effect on the final sound as well. Or the fact that you can adjust the P3 pot on the BA-3 front end stage to change the levels of 2nd verses 3rd harmonic distortion spectra if you do the FFT analysis (now available on REW!). Or the fact that capacitor C3 on the BA-3 front end stage can be anything from 1uf to 10 uf which will affect the low end response of the entire amplifier!

As you can see, there are NUMEROUS variables to a 'BA-3 amplifier' build.

But none of this may matter with regards to why Tyson prefers the 300B over his BA-3 version on one speaker or another. That's the fun part  .

Best,
Anand.

[maty]

Off topic

I had to have written: Maybe Tyson's First Watt BA3 works right only with 8 Ohms... 

Weeks ago I made some emulations of dominant H2 with the new soft Distort. Track: Bonaparte (Capercaillie), 16/44. Female vocal + acoustic instruments + synthesized. With H2 at -73 dB it sounded better at second intent, after I optimized the Distort soft to play multimedia!

First emulation:

https://www.audiosciencereview.com/forum/index.php?threads/beta-test-distort-audibility-of-distortions.10163/post-277664

and more in the same thread, with others complex music too.

The more interesting, to me: https://www.audiosciencereview.com/forum/index.php?threads/beta-test-distort-audibility-of-distortions.10163/post-277786

- End off topic -

[Captainhemo]

OK, I know you're going go ask - how does it compare to the Super 7?  I hate to say it but it's a tossup.  Haha, I never, ever thought I'd say that a speaker with a cone based midrange unit could keep up with my beloved planar drivers in the Super 7.  Yet it does.  There's a very slight edge to the Super 7 in ultimate speed and resolution, but the NX-Treme makes up for it with more power in the upper bass and lower midrange.  Danny should be proud, this is an incredible achievement.  I was skeptical that it could keep up with the Super 7 but it does so easily.  Impressive.

Hate to say it  man but,   I told  you   

And for you  guys  who like  power,  both the  NX-Otica's and NX-Tremes  love it.
Both models are 8 ohm nominal loads
jay

[Tyson]

Hate to say it  man but,   I told  you   

And for you  guys  who like  power,  both the  NX-Otica's and NX-Tremes  love it.

jay

Yeah man, you were right.  I was extremely skeptical, to say the least.  Both of them are exceptional loudspeakers.

[maty]

http://gr-research.com/nx-treme.aspx

Like NX-Otica the tweeters used are the new GR Neo 3 tweeters. The mids used are the 16 ohm M165NQ drivers that were designed just for this type of open baffle application. And covering the lower ranges are eight standard M165-16 woofers wired in a series/parallel configuration. So the bottom end is extremely tight and clean.

Sensitivity is 94.5db and the impedance is a nominal 8 ohm load. So they can be easily driven with small tube amps or chip amps...

-> https://parttimeaudiophile.com/2019/06/04/gr-research-dodd-audio-lone-star-audio-fest-2019/

Price of the complete kit with the flat packs is $2,995 plus shipping. The flat packs are shipped from Oroville, WA and there is an additional $400 fee for handling, packing, and shipping of the flat pack.

And, graphs!

On axis response and crossover point




Horizontal off axis response




Vertical off axis




Spectral decay




Impedance




Phase response?

[maty]

Your Price: $2,995.00 (+$495.00)

Sonicaps + Copper caps + Foil inductors <- $495.00

Complete kit: one or two speakers?

[maty]

https://parttimeaudiophile.com/2019/06/04/gr-research-dodd-audio-lone-star-audio-fest-2019/

Optimized and clarified

[Danny Richie]

All of our kits are listed and priced in pairs except for models that are designed to be used as center channel speakers.

[bsr]

Re: the 300b it just goes to show that you can't really predict how these things are going to go.  I too was very surprised that the BA3 wasn't the best match with the cone based speakers but it WAS the best match with the planar based speakers. 

I brought the 3 amps I did, because they are the ones I rotate around in the upstairs system with the Klipsch, the Dennis Had amps are more or less permanently installed in the downstairs system with the Super 7s.

I think the BA3 is just a warmer sounding amp than the 300b.  So it matched the planars better.

What preamp were you using with the BA3 and chip amp? Seems I’ve read Danny likes to use a passive (or buffer) pre...I wonder if the active stage of the Elekit integrated accounts for the improved dynamics?

[Danny Richie]

What preamp were you using with the BA3 and chip amp? Seems I’ve read Danny likes to use a passive (or buffer) pre...I wonder if the active stage of the Elekit integrated accounts for the improved dynamics?

We were using a battery powered Dodd Audio tube pre-amp. It isn't passive, but does have unity gain.

[RonP]

Stupid question: does toe-in matter with open baffle speakers?

[Tyson]

Stupid question: does toe-in matter with open baffle speakers?

Yes, but less than with box speakers.

[jtwrace]

We were using a battery powered Dodd Audio tube pre-amp. It isn't passive, but does have unity gain.

When will you switch to current production gear?