# Ribbon Midrange in a 3way design: Good idea?



## Veltinorian

I have in my living room Neumann KH 120A studio monitors but i also want more detail and fidellity. That's why I am about to start a 3-way speaker project with the HiVi RT2C-A ribbon tweeter (my X-Over Point would be 1.7-1.8 kHz) and have a question on the midrange. My choice is fallen in to a couple of speakers such as Tang Bang W4-1337SDF, Scan Speak Illuminator 12MU/8731T00. I have discovered recently there is a ribbon midrange speaker which can be crossed at f > 400Hz, with _safe_ crossing at 700Hz, the BG Neo8-S. The price is compelling as well, around 130 Euros (the Scan Speaks costs 265). It seems a lot of research was put in to it. The problem is i couldn't find much information about people building speakers with it. I want transparency and that attracted me to this. What do you guys think about this driver as a part of very high quality 3-way design?


*It has 8 inch height and here is how it looks like:*











I found also a local retailer, the specs described are impressive.
*Here is a local retailer:*

http://www.audax-speaker.de/index.php?module=shop_articles&index[shop_articles][action]=details&index[shop_articles][category]=4&index[shop_articles][data][shop_articles_id]=105


P.S. I intend to use woofer in the middle price range because of the midrange driver which should take care of the mid range issues a lot of woofers are known to have, My choice is fallen into:

Seas Prestige H1571-08 U18RNX/P Fs=43Hz with volume of Vas=0.8 cu ft
or 
Peerless Gold HDS-P830990 with GF Cone? Anybody knows what a GF Cone is??
or 
Peerless Gold HDS-P830875 with Nomex cone

They all have around Vas around 0.8 cu ft which will keep my cabinet small.


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## fusseli

There's no reason not to use it if it seems like a good match with your other drivers. Keeping adequate CTC spacing with the tweeter and the upper crossover point would be my concern with using the tall ribbon midrange. I've never heard a ribbon like that in real life, so I'd be curious too. I also believe that those should be easier to design with since ribbons usually have a ruler-flat impedance, unlike a conventional driver. For the woofer, since you can cross as low as 700Hz then you should have a lot of flexibility there. What measurement equipment do you have and how do you plan to design your crossover?


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## Veltinorian

Thank you fusseli for joining in. I have no concerns about the crossover, i can calullate it or even better use one of the famous automatic X-Over calculators. Why i am not that worried about it, it is because every single driver of the system will work in a frequency range that is very forgiving. For example the midrange driver is flat from around 500Hz but there will be some distortion below 600Hz. The producer recommends 700Hz for a safe point, I am gonna cross it at around 800Hz. The mids are linear practicly up to 5kHz and even above. Here comes the HiVi ribbon tweeter which can be crossed according the manufacturer from 1.7kHz and above but i am going to cross it at 2.5kHz so it's going to be easy and very forgiving on the mid and on the tweeter as well wenn distortions are concerned. The woofer will be also a high quality one and there will be no exception here about making it easy for it as well. As mentioned lower X-over frequency for the mid will be 800Hz, in this way for a quality driver such as Seas Prestige oder Peerless Gold this is not of a concern. I intend to use a high pass filter for the woofer tuned at around 50Hz so the driver will operate again a bit higher than designed thus minimizing the distortion for frequencies around Fs and below. Once again X-Over Points: High Pass at 50Hz, X-Over points 800Hz and 2.5kHz. I am going to trust the drivers as they are and not worrying about possible FR nonlinearities like + or - 1 to 2 dB across the entire frequency range. That could be the case in reality but in general those are tricky to compensate with passive X-Over. But taken into consideration the very forgiving frequency range for all 3 drivers are going to work with i am kind of confident that such phenomena won't occur at all.

@fusseli
What do you mean with that the center to center space will suffer because the mid is huge? Yeah it will take more space but do you think i need a lot of extra empty unused space in between the mid and the tweeter or between the mid and the woofer? Or you mean kind of unsymetrical alignment to save space in therms of the height of the speaker?

I have found here a speaker that uses 2 ribbon midrange drivers along with one tweeter, two 9 inch wofers and two 15 inch subs to handle the frequencies down to 20Hz. It's the Adam high end of the line main monitor S7A MKII.



It costs 15 999 EUR though. Solution design a speaker yourself.


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## fusseli

Yeah, if the mid is huge you will have a larger center to center spacing to the tweeter, meaning a more restricting limit in the highest crossover frequency possible. The rule out there is that: 13550 divided by CTC spacing in inches equals the highest possible crossover in Hz. As you get closer to this "limit" off-axis performance of the speaker will begin to diminish. For example, if your mid and tweet are 8" apart center to center, then the highest crossover you should consider would be about 1.7kHz. This may or may not be an issue depending on the drivers you settle on.

There's another rule out there for CTC spacing that is even more conservative but I'm not remembering it at the moment. There's a lot of discussion about this at PE TechTalk, if you are curious.


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## Danny Richie

I have been using the BG Neo drivers longer than anyone. I have had them as soon as they were available. Even BG sends their customers my way when they have application questions about using these drivers. I even have custom variants that I use in many designs like this LS-9.










Using it as a mid with the HiVi driver really doesn't make much sense. It is a much better driver than the HiVi in every way and plays to 40kHz.

As a mid it does not play as low as some may think. If you give up some sensitivity you can force it a little lower but still not as low as you'd think. In the line source pictured above they play down much lower than a single unit. In that application they cross at 850Hz.

In the LS-6 (next model down) only six are used in a line. In that application I can cross them as low as 1kHz.










Using them as a tweeter alone though leaves you with the same problem that you'll have with the HiVi tweeter. The tall height will greatly limit the vertical off axis response. When using a single tweeter of this type I typically go with the shorter Neo 3. It can be crossed in the 1,500Hz to 1,800Hz range. And the Neo 8 can only be crossed in the 1,000Hz to 1,200Hz range. So you don't gain much by going to the taller tweeter. And the Neo 3 has great vertical off axis response because it is shorter.

Another thing to keep in mind is that the mid-range is actually in the 300Hz to 500Hz range. So you will want to avoid crossover points in that area. And typically it is best to not introduce a crossover point to another driver until an octave above that range. So 850Hz to 1kHz is about it.

The only way to cover the actual mid-range with one of these types of drivers is to step up to the Neo 10. It can be crossed as low as 200Hz.










And these really aren't ribbon drivers. They are planar magnetic drivers.


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## Danny Richie

> I have no concerns about the crossover, i can calullate it or even better use one of the famous automatic X-Over calculators.


I really don't recommend calculated crossovers. They are calculated based on electrical parameters. That is really not the way to do it. That typically won't get you into the ball park. I do this for a living and would never design based on electrical parameters. 

Crossovers really have to be designed based on acoustic output of the drivers. This will take into account the surface reflections of the baffle, driver offset and phase relationships. If any of those things are changed then the crossover would also have to be adjusted to compensate. 

Here is a recent speaker upgrade that I did on a speaker that was basically designed based on the numbers and not measured. Have a look at how it turned out after I re-designed it based on the acoustic output of the drivers. 

http://www.hometheatershack.com/forums/gr-research/68386-vmps-626r-testing-upgrade.html


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## Veltinorian

@fusseli
What happens when the "13550 divided by CTC spacing" rule is not taken care of? It is interesting how the center to center distance influences the cross over point.


@Danny Richie
I am gonna be easy on the drivers since the frequency range they work with is verry narrow, this is no 2-Way speaker pushing the drivers to their limits. I intend to cross the drivers based on measured Thiele Small paramaters. For finer tunig with the sonic output i will measure and improve on a later stage some time in the future. What has your experience been with fine tuning the +/-1 or 2 dB peaks and valeys across the frequency range, do you hear it and is it worth the work?

You say the BG Neo is better than the HiVi tweeter but after 5kHz the curve for the BG Neo goes up very steep and uncontrollable so it would be difficult to compensate with the X-Over. And i think also it wont work in the linear range. That is why the HiVi comes in to help the BG Neo from 2.5, 3 kHz above.

The Neo 3 seems to have much lower surface than the HiVi RT2C-A therefore more prone to distortions in the lower freq range.

I cant undestand why should the the tall height will greatly limit the vertical off axis response?

I see what you mean with the 300-500Hz and using the Neo 10 and cross it at 200Hz. But those are the lower mids, what about 500Hz to 2kHz? I have seen some studio monitors have the 650Hz X-Over point.

Another issue may be deviating values for the impedance and the sensitivity which can be taken care of.

Do you guys see any other challanges to deal with?


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## Danny Richie

> I am gonna be easy on the drivers since the frequency range they work with is verry narrow, this is no 2-Way speaker pushing the drivers to their limits.


In the two way applications that these are used in they share the load with many drivers. Overall power being placed on each driver is very low. Also in a line source application the acoustic output rises as frequency decreases. This is due to low frequency coupling. So the crossover starts off with a cap value that is quite small. So electrically the BG tweeters see a load as if they were being crossed over at 5 or 6kHz. Acoustically however the crossover point is much lower. 

Using a single unit crossed in those ranges puts MUCH more demand on the driver. And crossing the top of its range off to another driver does not help it any. 



> I intend to cross the drivers based on measured Thiele Small paramaters.


That won't get you in the ballpark with these drivers. Crossover have to be designed based on acoustic output. Even changes to the cabinets baffle will cause the response to vary greatly. So designing from acoustic output is the only way to observe and correct for those effects. It is also the only way to see the phase issues. 



> For finer tunig with the sonic output i will measure and improve on a later stage some time in the future. What has your experience been with fine tuning the +/-1 or 2 dB peaks and valeys across the frequency range, do you hear it and is it worth the work?


Ranges like that are easily heard and have a profound effect on the tonal balance. 

Designing from T/S parameters my not get you to within +/-6 or 8db. Getting them to within +/-2db with those drivers is not likely. 



> You say the BG Neo is better than the HiVi tweeter but after 5kHz the curve for the BG Neo goes up very steep and uncontrollable so it would be difficult to compensate with the X-Over.


It does not. The response is very smooth. BG measures them in free air with no baffle. So their measured responses are a bit deceiving. They do need a notch filter for the peak at 13kHz though. 



> And i think also it wont work in the linear range. That is why the HiVi comes in to help the BG Neo from 2.5, 3 kHz above.


You are taking a very good driver (the BG) and in a range where it excels you are handing it off to a much lesser quality driver and causing an unnecessary phase shift and vertical off axis cancellations. 



> I cant undestand why should the the tall height will greatly limit the vertical off axis response?


That's simple physics. Anytime a driver covers a frequency range that is shorter than the width of the diaphragm then there is beaming. The height counts as well. With any of those tall tweeters the response across the top end drops off as soon as your ear gets above the on axis line. So your overall power response or in room response will lack some upper range air and spacial cues. 

This is why I only use the longer drivers (or long tweeters) in a line source application. They are not suitable as a tweeter alone. Same goes the the tall HiVi models. 

Drop down to the Neo 3 pdr and you will still have a very low crossover point, good power handling, and great off axis response in all directions. And these sound better than just about any driver out there if implemented properly. I use an OEM version with a deep back cup on all of our designs. The deep back cup doesn't load the diaphragm as much and has a more relaxed sound. 

Using them in an open baffle really takes things up a level too. 



> I see what you mean with the 300-500Hz and using the Neo 10 and cross it at 200Hz.
> 
> Another issue may be deviating values for the impedance and the sensitivity which can be taken care of.


Ideally you want the impedance balanced from end to end so that the amp sees the load the same across the board. Careful planing and measurement taking will get you both a flat response and a smooth impedance.


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## Veltinorian

I am gravitating using something like the Fountek Neo CD2.0 or the dayton PT2C-8 ribbon and cross the mid at 750Hz and 2.5kHz. Are there some similar alternatives as tweets you have come across that match the quality of the BG Neo8-S?

Scan Speak woofers go very low and have high Vas. The SEAS Prestige H1571-08 U18RNX/P with Fs=43Hz in only Vas=22l (0.78 cu ft) seems to be a very good candidate.

What order would you guys recommend the X-Over to be, maybe not less than a third order 18dB/octave?


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## fusseli

How did you come up with 750-2.5kHz? In my experience it's very beneficial to allow the midrange in a 3-way a full 3 octaves, or at least an even number of octaves. Aim for 2 or 3 exactly, not 2.5 or something. This is important for acoustic phase alignment across each band of the speaker. This is also the reason that I can't throw out a suggested slope to shoot for. Electrical and acoustic roll offs are two separate things and in my experience designing passive crossovers, it's tough to guess and get it right. That being said, a 3-way would probably benefit from steeper slopes. I'd shoot for LR4, that's what I have done in my mains.


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## Danny Richie

> I am gravitating using something like the Fountek Neo CD2.0 or the dayton PT2C-8 ribbon and cross the mid at 750Hz and 2.5kHz. Are there some similar alternatives as tweets you have come across that match the quality of the BG Neo8-S?


The Dayton. like the BG isn't really a ribbon driver. It is a planar magnetic driver. And both will have a limited vertical dispersion because of their height.

The BG Neo 8-S is a much higher quality driver than what you are considering crossing it over to even in ranges above 2.5kHz. The S version is a slightly higher sensitivity driver that will play down lower than the standard Neo 8. It can play down to the 750Hz range. So it could be used as a mid. If you really want to do a three way design with it then the Neo 3 pdr is a matching tweeter. 



> What order would you guys recommend the X-Over to be, maybe not less than a third order 18dB/octave?


Take it from a guy that does this for a living. You don't decide that before hand. That is kind of like picking out the wheels and tires for your next car before you pick out the car. 

You have to look at the acoustic output of the driver compared to what you are crossing it to and what type of crossover it will need. Then look at the time arrival aspects and phase relationship of the drivers at the crossover point. You have to be able to see those effects prior to deciding on the order of the crossover. Then whatever order that you try needs to be tested to see what the phase relationship is in the vertical off axis.


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## Danny Richie

> This is important for acoustic phase alignment across each band of the speaker. This is also the reason that I can't throw out a suggested slope to shoot for. Electrical and acoustic roll offs are two separate things and in my experience designing passive crossovers, it's tough to guess and get it right.


Those two statements are 100% correct. 

I do design work for various companies all the time, and have a ton of experience designing passive crossovers, and I would never guess at or calculate values based on electrical parameters. 

Let me throw this out there for educational purposes. 

I am designing products for Serenity Acoustics using the Neo drivers. You can see them here: http://www.serenityacoustics.com Here is a couple of pics of the Super-7 during testing that shows the drivers. 




























It uses Neo 10's and a custom Neo 3. Crossover points are 200Hz and 2.5kHz. They use a second order crossover between the Neo 10 and Neo 3, and there is one notch filter involved on the Neo 10. That is an LCR shunt to ground. There is no high pass filter on the Neo 10. In other words, no passive crossover on the lower end. Instead it uses a first order inline filter that plugs in before the amp. This first order filter plus the natural roll off of the Neo 10's makes an acoustic second order roll off. This matches the servo controlled woofers.

The width of the baffle is what determines the low frequency crossover point in this case. And the baffle width would also cause way too much surface reflection and disruption of the tweeters response. To counter that effect, and add some lower range gain, the tweeter is loaded into a shallow 3/4" thick wave guide. Even the back side of the baffle had to be designed based on the output from the back of the speaker. And the design of the back side also effects the output on the front side....

6 months worth of work went into testing various baffle shapes, wave guides, and driver mounting effects. All of those things plus phase relationships all effect the crossover design. Plus testing, measuring, and listening to various crossover designs can also be time consuming. 

If I could calculate a textbook crossover taking none of those things into account and have none of those things have any adverse effect then it sure would make my job a lot easier.


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## Veltinorian

(as i posted i dint see the prevoius post, the desings you post are impressive. This is a complicated design and the output can be hard to control though)

(the speaker i am about is more like this but with the planar mid http://www.troelsgravesen.dk/SP44.htm)

I really do not understand why you can't shoot for the X-Over point. When we here at the forum as DIYs can't shoot for the frequencies then who else? 

This range i meant is a proposal and a starting point for a discussion. It should be a compromise for all drivers and not pushing the drivers in a range where they have lots of distortion and where the SPL response is consistent vs frequency. I chosse those not from the electrical specifications but from the acoustical output from the drivers. Here is the acoustical SPL output vs frequency for the two drivers:

















Now the lower X-Over point 750Hz is almost as 2x higher than the lower Fs of the mid which is 400Hz. So the disortions will be at minimum. The frequencies up to 750Hz will be definitely up to the capabilities of the 6.5inch Seas Prestige woofer. The 2.5kHz is define-telly within the capabilities of the BG Neo8-S (recommended range from the producer is 400-6.000 Hz). And 2.5kHz is definitely within the competence of the Fountek NEO CD3.5 tweeter.

You consider the arrival aspects from the drivers as an issue, we are talking about less than an inch or so difference from the voice coils to the listener, this is not a matter of concern for me. Imagine you are in a concert hall where the whole orchestra plays. Is it that of an importance if the violin was a half inch closer or half an inch further away from the listener in relation to some high frequency instrument playing.

As for the phase the drivers act as a parallel LC-Circuit (with highest Impedance at Fs), the phase changes vs frequency and has a point where it shifts its polarity. The cone suspension acts like a C and the mass acts like a L. That would be a problem for waves of the same frequency but from different drivers being out of phase and cancelling each other for sure. But with a steep X-Over this becomes less of a problem. 
Here comes a phase shifter into place, what have been your expediencies and solutions on those issues?


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## Danny Richie

It's funny how different the two companies post curves. 

Since the BG is just measured in free air with no rear baffle then it looks very different than in an application. If you give it a nice sized air space behind it (another thing that requires some development and testing) it will be very smooth and flat holding about 93db of sensitivity through that lower range. 

The Fountek is on a graph with a much wider scale to make the curve look smooth. It also has an ideal baffle size to minimize reflections. It reality, or in most applications it is not that smooth. 

How those drivers are loaded, and the baffle effects change the response quite a bit and you can create problems that will change your crossover points. A driver may have a natural roll off that requires very few crossover parts but moving the crossover in one direction may require a more reactive or higher order network. So I always look at a particular response curve in the application or in the designed box to see what effect it had on the response. Go with natural acoustic curves if you can. 



> Now the lower X-Over point 750Hz is almost as 2x higher than the lower Fs of the mid which is 400Hz. So the disortions will be at minimum. The frequencies up to 750Hz will be definitely up to the capabilities of the 6.5inch Seas Prestige woofer. The 2.5kHz is define-telly within the capabilities of the BG Neo8-S (recommended range from the producer is 400-6.000 Hz). And 2.5kHz is definitely within the competence of the Fountek NEO CD3.5 tweeter.


Those premises are pretty good. But that woofer will only hit about 85db or so after some baffle step loss correction. So you will be padding down those drivers a lot to bring them down to that level. And padding them down 10db or more really hurts their sound. 



> You consider the arrival aspects from the drivers as an issue, we are talking about less than an inch or so difference from the voice coils to the listener, this is not a matter of concern for me. Imagine you are in a concert hall where the whole orchestra plays. Is it that of an importance if the violin was a half inch closer or half an inch further away from the listener in relation to some high frequency instrument playing.


Man, if it only worked that way...

It isn't just the physical offset of the drivers. The crossover causes delays as well. You can get into an area real quick to where you have 90 to 180 degrees of phase rotation. And as it approaches 180 the outputs do not sum. They start becoming less. So you can make a 15db hole in the response real easy. Even as things pass 90 degrees in phase rotation they can start to fall apart. This will mean as you move up or down in the vertical off axis the response begins to create a hole in the response. This means some of your in room response and imaging gets bad. 



> As for the phase the drivers act as a parallel LC-Circuit (with highest Impedance at Fs), the phase changes vs frequency and has a point where it shifts its polarity. The cone suspension acts like a C and the mass acts like a L. That would be a problem for waves of the same frequency but from different drivers being out of phase and cancelling each other for sure. But with a steep X-Over this becomes less of a problem.
> Here comes a phase shifter into place, what have been your expediencies and solutions on those issues?


It can be less of a problem if the crossover uses very steep slopes and it is less of a problem in longer wavelengths. So the lower the crossover the more the physical offset is less of an issue. There is still the electrical shift caused by the crossover though. There are a lot of non-textbook ways of shifting phase with the crossover to maintain good phase coherency over a wide range. Solutions vary from speaker to speaker. 

I don't want it to sound like I am discouraging you. I will help you and try to steer you in a way that makes it easier for you. But you are biting off a lot with these drivers and no real tools needed for the job. 

And if you took the Neo 8 alone and by-passed any resistor that you use to lowers it output with a small cap value, plus a notch filter on its peak, then the upper end response will be just about as smooth and extended as the Fountek ribbon, and it would sound a lot better. The BG is a much better sounding driver. I know, it doesn't look as cool, but it sounds much better. The only limitation then would be the limited vertical off axis. That still might be a better option than adding the Fountek though.


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## Veltinorian

I made a research and found a OEM supplier of very high quality amps used for professional audio systems, studio monitor manufacturers, also multi channel solutions, DSP options available:

http://www.powersoft-audio.com/en/products/amp-modules/d-cell504.html

The question is whether they will sell to a private DIYer


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## Veltinorian

I found a very very high end mid, even the people from the Troels Gravesen's site (officially recomended DIY builds from the scan speak web site) admit it's the best they have ever heard..it is a ceramic driver, here is a fully documented 3way build with it:

http://www.troelsgravesen.dk/SP44.htm

Is it worth considering the BG Neo 10?


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## Danny Richie

Veltinorian said:


> I found a very very high end mid, even the people from the Troels Gravesen's site (officially recomended DIY builds from the scan speak web site) admit it's the best they have ever heard..it is a ceramic driver, here is a fully documented 3way build with it:
> 
> http://www.troelsgravesen.dk/SP44.htm
> 
> Is it worth considering the BG Neo 10?


That's interesting. If it's the best mid-range they ever heard then why wasn't it used to cover the mid-range? In that design the mid-range is being covered by a Scan Speak woofer. And while at the same time covering low bass. So it has little advantage over a two way design. 

The heart of the mid-range is 300Hz to 500Hz. If you want to increase clarity and take advantage of the three way design then what you really want is to relieve your mid-range driver of having to cover longer wavelengths that force the driver into long exertions. 

So if you remove from your mid just the first octave of 20Hz to 40Hz that's actually a pretty big deal. That's taking away over half of its work load. Step it up and remove the first two octaves so that it is not having to cover from 80Hz and down and now you have removed about 80% of its load. How steep of a slope makes a big difference of coarse, but you should be able to get the idea. Now if you have a lower frequency woofer that can match the speed of the mid then stepping the crossover up one more octave to 160Hz or so will really relieve the mid from low frequency duty. Now you will really notice increased clarity in the mid-range. 

I applaud the designer for looking at the off axis response in the vertical and horizontal. But the response in the vertical off axis in this design is not good. And the designer realized that stating:



> "Now, making a point of crossover at 6 kHz is calling for trouble with regard to crossover lobing and this is no exception."


He then follows it with a statement that is dead wrong though.



> "The good thing is that 6 kHz is really high and not representative of what we actually hear, as our two ears (fortunately) do not work the same way as a 5 mm microphone capsule."


Actually those effects are quite easy to hear, and that effect matches his subjective observations in the next paragraph.



> "The sound from crossover version #2 was indeed very promising. Lots of detail and transparency, but also a distinct character from the C44 working up to 6 kHz. A sound very hard to describe. Not really fullrange kind of sound, but slightly "cuppy", i.e. like when you hold your hands around your mouth and speak. This doesn't appear to be derived from a too high upper mid level, rather limited dispersion, which is strange as the horizontal dispersion is excellent. But measurements are one thing, not always reflecting what we aurally perceive. At 6 kHz we're close to where the C44 will start beaming due to the diameter of the cone and maybe we're just pushing our luck from taking a 2" dome this high."


Looks like in version 3 he corrected that a little bit, but not by much. He left his top end pretty soft too, but maybe he likes it that way. 

I also applaud his crossover design statements and agree with this 100%. I have been saying the same thing earlier in this thread. 



> Most common mails go like this: "I have these and these drivers; can you please make me with a crossover?" I can't, because to make a crossover I need this:
> 
> - Frequency response and phase from actual drivers mounted on actual front panel.
> - Impedance/electrical phase of all drivers mounted in actual cabinet.
> - Acoustic distance from drivers to suggested listening point.
> - In short: I need your finished speakers on my workshop bench.
> 
> In very few cases I may have the actual drivers and a suitable test cabinet and I can set up the drivers and do what's described above. We're then into diy-service work and it usually takes 5-15 hours depending on overall complexity. This only provides a crossover that actually works on some basic parameters like frequency response, phase integration, power response, etc., but no guarantee it also sounds good.
> 
> The question is whether we can make a crossover at all without measurements
> - and the answer is NO. It cannot be done, and crossovers cannot be calculated.
> 
> We cannot use manufacturers' data sheets to simulate crossovers either. The frequency response data are most often taken from an "infinite" baffle that does not in any way resemble your cabinet. These data do not contain proper phase data, etc.


In regard to the Neo 10's. From 200Hz to 2.5kHz I have not heard anything that touches it. This is a true mid-range driver. It is very sensitive though how it is loaded and used. So baffle effects and how it is loaded effects the response quite a bit. This effects the crossover considerably. I would not recommend using it in a DIY design unless the designer was using a measuring system of some kind to see these effects.


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## Veltinorian

@Danny 
I am almost 100% convinced on the Neo 10. And the fact that once the woofer is reliefed from the 300-500Hz range the mid speakers sound very clean where the Neo 10 can deliver. How about some very expensive main studio monitors for example the 8000 € ($ 10480) Klein + Hummel O 500 (uses a 3" dome mid) which is crossed at 520Hz/2.8kHz and the big 5400 € ($ 7074) 15" Genelec 1038A (uses 5" cone mid) which is crossed at 410Hz/3kHz? Do you think that a carefull designed speaker with the Neo 10 can come close to those?

http://www.neumann-kh-line.com/neumann-kh/home_en.nsf/root/prof-monitoring_discontinued-monitors_studio-products_O500C#

http://www.thomann.de/gb/genelec_1038_a.htm

And the uneven FR of the NEO 10, in the range between 300Hz and 3kHz there is 15dB difference, would it correct itself once mounted on a baffle, which actually happens with woofers?


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## Danny Richie

With the heart of the vocal range being in the 300Hz to 500Hz range that is not a good place to have a crossover. You really don't want to split that range into dissimilar drivers with different offsets and a phase shift. So I wouldn't say that either of those speakers are good examples of a well implemented three way design. 

You have to keep in mind though that the factory measured response of the Neo 10, posted by BG, is in free air with no baffle. So it really does not reflect what the response will be like on a baffle. Like I said these drivers are very sensitive to baffle effects and rear chamber loading. Open baffle applications are even more tricky. They can produce a very smooth response or a really rough one. It just depends on the implementation.


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## Veltinorian

I have read a lot of reviews and DIY build threads recently and for some reason I gravitate towards the Dayton RS52 dome mid.

Do you think a have a good shot using the RS52 with a ribbon tweeter such as the Dayton PT2C or the Fountek NEO CD2.0 or even the horn loaded NEO CD3.5? Or I should stick to the simular dome tweeter such as Dayton RS28F for better line up with the dome mid RS52? For better lining up the accoustical centers when using the Dayton tweeter RS28F would it be a good idea to use one of their waveguides such as H45E, also more natural sound or it isn't worth the bigger dimensions after introducing a horn quide into the system?


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## Danny Richie

The Dayton mid is not a bad mid, especially for the money. But keep in mind, it won't cover the actual "mid-range". It won't play low enough to do that. So let's say you cross it over at 900Hz so as not to add a crossover in the actual mid-range and 2.5kHz. You are barely covering 1 and 1/2 octaves. So you have to ask yourself if it is worth it and what benefit will there be? Will it be worth the cost and complexity that it will add to the crossover? 

The Dayton tweeter that you listed is too all to use as a single tweeter. It would have too limited of a vertical dispersion. The only application I see for it is a line source. 

The Fountek is an okay tweeter as well, but not something that I'd personally choose. I wouldn't even want my audio signal to pass through the steal screws that they use for connectors. 

Also keep in mind that you can't just grab a tweeter and throw it into a wave guide. Chances are about 95% that the response will be a mess. And with the one that you posted a part number to I can guarantee you throat cancellation effects. Wave guides have to be designed and built per each tweeter. And what works great on one tweeter can make a mess of the response on another.


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## Veltinorian

I found a DIY kit from the same web site which is authorized to sell the BG Neo in Europe (actually they have an anaechoic chamber and work together with Sony) and a review from a prestige Magazine in Germany. They refer to the kit as a very open, almost unheard-revealing speakers. The audax in turn have been on he scene for 35 years and seem to be a respectable company, as loudspeakers from other companies are being there developed and so on. I am sold on the BG Neo10+Neo3. Here is the kit:

http://www.audax-speaker.de/index.php?module=shop_articles&index[shop_articles][action]=details&index[shop_articles][category]=2&index[shop_articles][data][shop_articles_id]=83










It is 1069 Euro with 2x 8-inch custom Usher woofers and X-Over. It is too expensive though. I played with the REW a little bit, I am gonna order the miniDSP UMIK-1 mike and will design the X-Over with your help myself  There isn't a rear plate on the Mid-Cab, only solid layers of damping material from Polyester. X-Over points are 300Hz and 3kHz.

I'll come back as soon I have something going on with the delivery of the Neos. Besides the autors of the review for this Kit say it reaches the performance and quality of the 20000+ Euro speakers. It depends how good the X-Over will be though. It will cost me 110Euro for the Neo 3 and 280Euro for the Neo10. From the woofer side i didnt decide yet, i think something like 6,5 Seas Excel or a Accuton driver.


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## Danny Richie

They missed the boat on that design in a few areas. They added too much surface reflections around the Neo drivers. That will actually cause a bump in the response of the Neo 10 that the crossover then has to correct. They also failed to separate the front to back wave, and that keeps the Neo 10 from playing down low enough. So the crossover gets pushed up too high into the mid-range. That's not good. 

Also, the MiniDSP is a fun tool to play with but sounds absolutely horrible. The D/A conversion is equivalent to a $49 CD player from Walmart. There is a reason they are sold so cheap. They are cheap! The parts quality is the bottom of the barrel. If you want to suck the life right out of the music then that will do it. 

What you need below the Neo 10's are fast bass drivers. And while the Accuton is great all around driver it is not a driver one would choose for 200Hz and down. The Seas Excel is just a problematic mid-bass driver that doesn't sound very well. I wouldn't use it in anything if I could help it. 

It is also very hard to match the speed of the Neo 10 with anything. The only way I can see making it work was with servo control. For a non-servo controlled woofer consider using 4 series paralleled mid-bass woofers (5.25" to 6.5" woofers) in a sealed box and let the first octave and a half be handled by external subs. Look for light weight paper based woofers with low moving mass.


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## tojoko

[/IMG]Hi 

I read the article about your idea for a 3 way system with the use o the B&G Neo8-S, here is a pic of my system, not completely finished, but absolutely very good sounding, the sound is very 3 dimensional and fast, the advantage of a dipole system, the only (little) minor side, it can not sound as loud as a PA system, but loud enough for a livingroom, i used the REW5 software to measure the system, it needed very little tampering, I use a digital active crossover, totally changed to suit my system, passive output and built in 6 way preamp and discrete PSU instead of the switching, that came with the unit, it drives 3 (very old) Kenwood poweramps, 2 M1's fot the satellite and 1 M2 for the Disub subwoofer (in the middle).
So the complete sysytem is a dipole system, including the subwoofer.

Tojoko


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