NaO Note II RS

I had not planed on "showing" this new version of the NaO Note just yet, but with the up coming release of the Linkwitz LX521 I thought I should get it out there. It still has to be finalized, which will come some time this winter. There is just more to do in the spring, summer and fall other than to work on speakers. :)

Please see my NEWS web page or a brief look at some details about the speaker.
 
Yes, and I reckon SL will be using LR4 paradigm again as well in analog.

For your vertical driver spacing and crossover, what is the vertical off axis behavior?

Andrew

The baffle layout is not fixed yet. The history goes like this. The Note II had two objectives: 1) replace the dual lower 18cm mids of the original note with a single 22cm mid (ScanSpeak Discovery 22w), and 2) improve the dispersion of the tweeter, both vertically and horizontally. The intent regarding the later was to retain the Neo 3 tweeter behind a circular wave guide (which is what the baffle was cut for). That worked fairly well, except the reduced radiating area resulted in a reduction is sensitivity form the Neo3 which was unacceptable. This prompted the use of the 3/4" dome. However, what you see in the prototype is the baffle cut for the Neo 3 with the 3/4" dome inserted. The tweeter appears to be excessively separated from the upper mid because the position of the wave guide was dictated by the dimensions of the Neo 3. The baffle be needs to be re-cut with the tweeter spacing reduced. Additionally, I my play around with the crossover between upper mid and tweeter since lowering the x-o point would further improve vertical dispersion. Additionally, I may try a higher order LR between upper mid and tweeter to further mitigate the vertical lobing. If that can be done without degrading the horizontal response, that is what will be done. So, I can not answer your question at this time. As I noted, I did not plan on presenting the speaker at this time but I felt prompted to do so with the upcoming release of Linkwitz's LX521.
 
I don't know much....but the larger mid driver is not a CA22RNX. Both midrange drivers are special versions of existing Seas drivers that are not yet available.

The system is 4-way...3-way active...with a passive network between the two midrange drivers. I'm not sure of all the crossover slopes, but I do know they are not all LR4.

For those of you in the SF bay area, the system will be demo'd at the Burning Amp on October 28th.

We Orionphites will no doubt be orgasming uncontrollably in a few days. :)

Sorry to jack the thread.

Dave.
 
I don't know much....but the larger mid driver is not a CA22RNX. Both midrange drivers are special versions of existing Seas drivers that are not yet available.

The system is 4-way...3-way active...with a passive network between the two midrange drivers. I'm not sure of all the crossover slopes, but I do know they are not all LR4.

For those of you in the SF bay area, the system will be demo'd at the Burning Amp on October 28th.

We Orionphites will no doubt be orgasming uncontrollably in a few days. :)

Sorry to jack the thread.

Dave.


More than happy to see info about the LX521. Feel free to post here if you like. But a hybrid design with passive x-o between upper mid and tweeter? SL is making progress. :) (intended as a light hearted comment.)
 
Hi JohnK .... and any other NEO3 dipole tweeter users,

To your ears, what sounds better as a dipole tweeter: the NEO3 or a back-to-back pair of 0.75" domes?

Hard to answer that in my applications. The dome in the wave guide has soemwhat better control over directionality and is more extended. I don't know if tha equates to sounding better. Neither tweeter is being pushed very hard in my cases.
 
Neither tweeter is being pushed very hard in my cases.

John,

Thanks for the tweeter discussion. Your comments match my understanding .... your decision for a high 6Khz xover from the 3.5" ScanSpeak 10F upper midrange in your design allows many tweeter choices, both in diameter and cost.

I have attached the Pdf of the $60 Faital 10" midbass 10FE200 which has a Qts = 0.6, Fs= 55Hz, and Xmax =4.6mm which could be another lower midbass option for your new speaker.

The $80 ScanSpeak 10F allows using low cost 0.75" tweeters and a low cost midbass.
 

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  • 10FE200_datasheet.pdf
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The way it is, it will be all ScanSpeak Discovery except for the Vifa tweeter, 10" woofers, 8" lower mid and 4" upper mid. Tweeter is the Vifa OX20SC00.
And, as I said, it will be all active with dsp crossover. I will provide the specification for the transfer functions so that any dsp crossover can be used (or it someone wants to design an analog version). I will also supply a configuration file for the miniDSP 2x8 (or the newer 4x10 Hd which is the same as the 2x8, but in a finished enclosure).
 
Thank you for sharing the design process with us!
As you may know already Lynn Olson has been revealing details of his latest design as well. His goals are arguably different but he insists on using one driver through the most sensitive 1-3kHz region. Similarly to your design he plans to use a supertweeter for improved directivity in the last octave. He advises a steep slopes crossover around 7kHz.

Although a crossover that high in frequency will result in multiple lobes on the vertical axis the common understanding is that they will be difficult to perceive. Would you please share some of your own insights about this design approach?
 
Thank you for sharing the design process with us!
As you may know already Lynn Olson has been revealing details of his latest design as well. His goals are arguably different but he insists on using one driver through the most sensitive 1-3kHz region. Similarly to your design he plans to use a supertweeter for improved directivity in the last octave. He advises a steep slopes crossover around 7kHz.

Although a crossover that high in frequency will result in multiple lobes on the vertical axis the common understanding is that they will be difficult to perceive. Would you please share some of your own insights about this design approach?

I have been looking at different crossover points and slopes between the upper mid and the tweeter. That is the thing about dsp crossovers, they can be changed easily and quickly. Basically, I design the crossover with a number of active blocks (HP, LP filter, shelving filters and Q boost/notch filters) with typical software and model the response. Once I have determined the circuit parameters they can be used to implement the dsp crossover filters and verify the modeled result, listen and decide if the result is satisfactory. I'll concentrate on the uppermid/tweeter x-o since the lower mid/upper mid x-o really isn't an issue. I'm currently looking at 4th to 8th order slopes between uppermid and tweeter and also lowering the x-o point from 6k to 4k Hz. The lower x-o point and steeper slopes improves vertical lobing between the upper mid and tweeter. But also, recognize that if the lobe give good dispersion of over +/- 15 degrees that means the listening window at 10' from the speaker is about +/- 2.5' relative to the design axis. And, as I said, with a dsp crossover it is a very simple matter to add delay to change the direction of the main lobe. This is one of the very nice features of using a dsp crossover as opposed to analog active or passive where the offset delays are typically fixed to direct the main lobe on the design axis.

I'll also point out that when this design is finalized I will be supplying configuration files not only for the miniDSP 2x8 but for the Bodzio Ultimate Equalizer PC based dsp crossover which will allow the system to be completely linear phase, thus transient perfect on the design axis.
 
To your ears, what sounds better as a dipole tweeter: the NEO3 or a back-to-back pair of 0.75" domes?
Does a back-to-back pair of Dayton ND20FA-6 count as 0.75" domes?
I haven't compared them side by side with the Neo3 - there have been about 2 years between them. But still I can tell you what decides over which is better: the front wall condition.
With those back-to-back drivers you always have the option to attentuate the rear driver somewhat - or even switch it off. With the Neo3 it became inevitable to take absorption measures at the first reflection points of the front wall. In both cases I have tried to keep the baffle around the drivers as small as possible - using none.

It is quite an eye-opener to me when I see how both SL and john k are somewhat ambivalent about the use (or not) of the rear dome.

Rudolf
 
It is quite an eye-opener to me when I see how both SL and john k are somewhat ambivalent about the use (or not) of the rear dome.

Rudolf

Ambivalent? I wouldn't say that. I've always favored a rear tweeter on a dipole. I did not have a rear tweeter on the Mini, but that was kind of an "introduction to dipoles" speaker intended to show the character of dipole midrange. Bout the NaO II and Note have front and rear radiation all the way up. This new version of the note will probably have a rear tweeter but currently doesn't more due to the way the design has progressed (see post 3). I think the roll of the rear tweeter is a very different when having a crossover at 1.4k (Orion) or 2.2k (NaO II) or 4k-6k (Note).

I agree that the front wall (that behind the speakers) is critical and I highly recommend treatment of that wall, and the room in general, to achieve the optimum sound and image. I fully endorse the idea that the room is a component in the system and a major one at that.
 
Hi Dave,

I really don't care to revist the "flat in not correct" argument. My approach has always been to design the speaker to have flat axial response and provide the ability for the listener to make adjustments to the characteristic on the top and bottom ends. With dipole designs like the NaO II and Orion there are issues with tweeter bloom that I believe have an impact on what the top end should be. And while cutting or boosting the top end will have an overall impact on preception, it maintains the ratio of direct to reflected sound. Improving directivity, and adding/removing damping to/from a room, on the other hand, has the effect of changing the ratio of direct to reflected sound. Maintaining flat response and making such adjustments can have the exact same effect on the reverberant sound field as shelving down or boosting the high end response. The differences comes in the direct sound.

I would agree that the reverberant sound field should generally have a downward slope as the frequency rises, but I would hesitate to suggest that the direct sound should be follow suite.
 
Not my intention to start this discussion all over again either. Especially not in this thread. But my omnis have taught me that the flatness of the FR is determined by the diffusivity of the sound field (which is a result of dispersion width and decay properties of the room) and psychoacoustic demands related to diffusivity.
Very directional speakers like Geddes' need a flat on-axis FR. But every moderately wide dispersion speaker should/can deviate from that if the room is not exactly a stuffed pillow. And my dipoles in my room fall clearly into a category for a non-flat equalization.