The Miniliths: A project based on the Seas CA21REX, Neo8 PDR & Neo3 PDR

[fjhuerta]

Update...

After living with the speakers for a while, they became my reference units. The Neos are really something - I suppose their attack - decay times make them sound "different".

Bad thing is - I blew a CA21REX.

Oh. Well, I didn't "blow" it. Or maybe I did. I was listening to the Blue Man Group, and one of the woofers started making a rapping noise. I was pretty sure I blew it. But when I looked at it, it was fine (the cone, that is) - the tinsel leads came apart from the cone, and the voice coil wire broke down. No matter what I did, I couldn't fix it.

And, I realized Madisound doesn't carry the CA21REX anymore. I think Solen still does, but it's a different CA21REX - apparently, Madisound had an "Innersound" branded model with slightly different specs. Anyway...

Looking for a replacement woofer, I found the SEAS CA22RNX. Close enough, but the frame is a bit bigger, and my grilles are tightly built around it. So it wouldn't be very useful. And the T/S & efficiency parameters aren't even alike.

Metal cones (like the RS-225) were out of the question. I simulated the in-box response of it, and efficiency was way down, and the crossover became extremely complex from taming the upper peaks.

I settled on the SEAS P21RF/P. Same size as my old CA21, the T/S parameters matched the enclosure.. although efficency will go down at least 3 dB. It's a champ, though - in box speaker response is beautiful - I bet many people could get away with a 2nd order acoustic response with just an inductor.

Anyway, I just took some new measurements of the drivers in box. Much to my surprise, the Neo8 changed its performance quite a bit - it has more output in the lower midrange (around 800 Hz or so). The Neo3's response is as terrible as always (since those were used units, I'm not surprised).

I've modified the crossover so that it can use the 21RF/P unit. I need to take some off-axis measurements before posting it, though - I need to make sure the off-axis response takes care of the jagged FR of the Neo8 and Neo3.

Well, at least now the design is current again - since it's using available drivers.

BTW - now I know why SEAS is a bit more expensive than Dayton. I don't know about motor specifics, but SEAS and Peerless shure have beautiful FR curves... so smooth and easy to work with.

[minkuni]

The new Seas CA22RNY could be a replacement for the old CA21REX. The chassis is of course the new 22cm type.

[mjon]

Very interesting thread and project!!! Could you post a picture of the finished speaker?

/Magnus

[fjhuerta]

Minkuni, you are right, the CA22RNY has the efficiency and the FR needed! Vas is bigger, though - I think I'd have needed a bigger enclosure. The thing that hurt me the most was losing a couple of dB's - I liked the efficiency of the finished speaker.

Magnus, thank you! Here are some pics with the old CA21REX:

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[mjon]

Really, really nice!!! This was clearly the most interesting Neo-design I've seen.

Did you make the subenclosures for the Neos deeper in this version? What is the size of the whole speaker?

/Magnus

[fjhuerta]

I've been looking for the speakers' drawings everywhere...I believe I lost the file somewhere! I need to re-draw them and post them here. I'll probably do such a thing this week-end.

Anyway, the Neos' chambers are 1". The front baffle is 2", so I just did a cut-out on the front 1" baffle. It really does help the low end of the Neo3, extending it quite a bit. Then again, its FR is so jagged this isn't a big benefit. The Neo8 is far easier to work with, in my opinion.

I finished modeling the new crossover for the SEAS P21. Good news are many - the design is simpler, FR is flatter, and the parts are cheaper. Plus, the load is far easier on the amp. Bad news, obviously, are the loss of around 4~5 dB's in sensitivity.

I actually like the sound of the P21 a bit more than the paper version. Bass is a bit more solid, and since the crossover was reworked, the addition of resistors to the design meant I could achieve a midrange response a bit flatter, plus I contoured the high frequency so that off-axis response is far better. One big minus of the original design was a small sweet spot - the new one has a wider one.

It's good to have these speakers back. I didn't remember how much I love the Neo8 sound.

I'll post the new crossover sometime during the week-end.

[mjon]

How are things going with the new crossover? Is it stable yet and will you post it and the measurements?

/Magnus

[fjhuerta]

I was very lazy posting this... sorry about that.

Here's the new crossover for the SEAS P21.

I've been living with this speaker for quite some time now, and I prefer it to any other designs. The Neos have a certain sonic signature to them (more accurately, they don't have any sonic signature, in my opinion) that makes me go back to them all the time. They are a joy to listen to - never tiresome, aggressive or misbehaved in any way. The only shortcoming I really dislike is the fact that they don't have a great off-axis response. I tried to minimise this problem in this design by aiming for a 30° flat frequency response, and it helps.. when you are at or near the sweet spot.

These have been my reference speakers for quite a while.

Impedance: Quite a bit more benign than the first design. The design is about 4 dB less sensitive than the original one, though.



Transfer functions: smooth transitions all around.



Frequency response at 30°: The Neos measure badly at 0°, but at 30° they behave nicely.



Final crossover design: Most of the parallel caps are shown like that because that's the way I built the crossover (I wanted to use a couple of stuff I had from previous projects).

[augerpro]

I've always wanted to listen to these BG's. Too bad you're a bit far from any of the US diy meets, it looks like a great speaker!

[Jonasz]

Interesting!

Does this mean you have to listen to them 30° off-axis to have a flat response? Do you have a measurement at 0°?

[Jonasz]

Well?

[fjhuerta]

Time to revive an old thread.

I still think these are the best speakers I've ever designed, and they are in my "reference" system. Time has only made me love more and more the Neos - especially because my living room has hard floors and many reflective surfaces, and apparently the Neos controlled vertical directivity makes the speaker sound much better than other designs with better vertical dispersion.

Anyway, I did create a new version of the crossover. Reason being, the speaker sounds extremely well when listened at a very specific sweet spot - ears at the Neo8 height. At that point, the midrange is extremely well rendered, and the highs blend well. Unfortunately, when you stand up, the speaker loses its coherence pretty fast.

The new version of the crossover drops the crossover point to the Neo3 down to 3.5 KHz, which helps a lot in this respect. The speaker now sounds a lot better around the room. The midrange still sounds great - I believe the trade-offs (the midrange may be a bit better with the first version) may be worth it if you are going to be listening to the speaker around the room, instead of sitting still.

I'll be posting the design tomorrow. Crossover topology is the same - only some values changed.

[Russ_L]

Welcome Back

Javier- glad to see you back with more info on the Miniliths. I'm a big fan of three ways and interested in building either your Miniliths or the Statement Monitors as my first DIY project. I will need five for my multichannel SACD / HT theatre set up.

Before I got the urge to build I was very interested in buying :E five of the Eminent Technology LFT-16s or (even) the LFT-8s http://www.eminent-tech.com/main.html. I think both are tremendous values for the money, but again I have the bug, although not one iota of woodworking capability.

Keep up the good work. On my part I've just finished reading Chapter 2 of Speaker Building 201.

Russ

[fjhuerta]

Hi Russ,

Here's the design.

The changes I made to the original are:

* Lowered x-over point from the tweeter to the midrange: 3.2 KHz, LR-4.
* Added a series filter to the tweeter. The Neo3 has a rising response in the top-end, and although you could avoid using this filter, I found using it makes the speaker sound a bit more natural. The exaggerated highs are very obvious when you remove this piece.

Here's the schematic. I used Dayton polypropylene caps all around, except for the shunt ones, which are basic non-polar electrolytics. The big inductor on the woofer is an Erse 14GA with an iron core, in order to keep sensitivity higher.



The impedance is fairly benign, with a single 3.5 Ohm point in the midrange.



The frequency response is very similar to the original design's one, but the power response is vastly improved. The tweeter's response is better controlled in this version, too.



I'd definitely call this the better of the two designs. After comparing it to my own commercial speakers (Monitor Audio RS8, Energy Connoisseur 7) and my own DIY designs, these are my favorite speakers.

[Mudjock]

Javier,

Thanks for posting this. I have a pair of Neo8's begging to be put into service and your writeup gives some good guidelines on what to try with them.

Scott

[xumbug]

Hi Javier,

Any uodates on the neo project, has any one else built these. I have pair of neo3 pdr's and 8 looking for a home. Are you still happy with your final design. Looking forward to your reply.

Best regards

Stuart

[fjhuerta]

Hi Stuart,

They are still my favorite speakers. You may have to play around with the padding on the Neo8 / Neo3, depending on your listening distance (a bit more padding if you are listening to them farther away).

Their mids are outstanding...

[xumbug]

Hi Javier,

Thank you for the reply! I want to use them with a HiVi D8.8+ , this is an amazing driver and is very quick and dynamic, the bass section will be 28litres and will go flat to 33hz in that cab. Do you think the neo's will work ok with it. What is the volume of the box for the neo 8. Lastly is it ok if i use the Neo3pdr that has its own back cup?

Regards,

Stuart

[fjhuerta]

I don't think see why the D8.8 wouldn't work. The bass crossover would need to be redesigned, but the overall topology would remain the same, since I believe the HiVis also have a smooth response (not as smooth as the P21, but still nice).

I'm not really sure about the Neo8 volume. The enclosure, though, is 3/4" thick and the size of the Neo8. The same thing goes for the Neo3. I'd suppose not removing the Neo3 back cup wouldn't matter with a crossover at 3.2 KHz. I saw more extension without the cup, but you wouldn't really be using it at all.

[xumbug]

Hi Javier
Here are the specs of the D8.8+. Do you think you could help me with the woofer x over design, or the change in values of your x over.





D8.8+ Bass-Midrange





Shallow mineral filled polypropylene cone;
Fatigue resistant foam surround;
Inside vented magnet system with huge Ferrite magnet;
Long-throw symmetrically driving motor structure;
Extreme power handling voice coil with 100mm diameters black anodized aluminum former;
Progressive spider with decompressed rear volume.
D8.8 represents a design where the voice coil is positioned over an undercut central pole piece with a large thermally stabilized Neodymium magnet at the bottom and high energy ceramic magnet on the top. A specially shaped, CNC machined steel cup completes the magnetic structure from the outside, creating a shielded magnet system with symmetrical flux density distribution along the gap. The long-throw voice coil experiences a symmetric driving force and substantial decrease of inductance and back electromotive force modulations. The whole magnet structure is optimized using Finite Element Analysis. The result is a radical improvement of driver linearity. The cone has a shallow, high integrity structure, which is extremely rigid and dynamically stable.
The large voice coil diameter allows more uniform cone excitation, thus improving phase and transient characteristics of the driver, resulting in clear and accurate reproduction. The vented design, effective and uniform cooling of a high temperature rated voice coil provide a dramatic increase of power handling.
D8.8 is excellent as a woofer for high power "no compromise" audiophile systems. It also may be used as a subwoofer in various configurations.





Products Graph:


Mechanical Drawing
(Magnify)

Impedance
(Magnify)

Frequency Response
(Magnify)



Bottom View
(Magnify)

Top View
(Magnify)

Part View 1
(Magnify)

Part View 2
(Magnify)




More picture Woofer D series: Please choose... D5.8 Bass-Midrange D6.8 Bass-Midrange D10.8 Hi-end Woofer D8.8 Hi-end Woofer D8.8+ Bass-Midrange D5G Bass-Midrange D6G Bass-Midrange D8G Bass-Midrange D10G Bass-Midrange




D8.8+ Bass-Midrange
Nominal Impedance (Z)(Ω) : 8
Resonance Frequency (Fs)(Hz) : 31
Nominal Power Handling (Pnom)(W) : 150
Max Power Handling(Pmax)(W) : 300
Sensitivity (2.83v/1m)(dB) : 86
Weight (M)(Kg) : 4.2
VC Diameter (mm) : 100
DC (Re)(Ω) : 6.5
VC Length (H)(mm) : 23
VC Former : CCAW
VC Frame : Kapton
Magnet System : Inside
Magnet Former : Ferrite
Force Factor (BL)(N/A) : 13.3
Gap Height (He)(mm) : 8.0
Linear Excursion (Xmax)(mm) : 7.5
Suspension Compliance (Cms)(uM/N) : 425
Mechanical Q (Qms) : 6.16
Electrical Q (Qes) : 0.44
Total Q (Qts) : 0.40
Moving Mass (Mms)(g) : 62.7
Effective Piston Area (Sd)(m2) : 0.0241
Equivalent Air Volume (Vas)(L) : 34.9
Cabinet Type : Vented
Recommended Box Volume(Vb)(L) : 40
Tuning Frequency(Fb)(Hz) : 30
-3dB Cut-Off Frequency(F3)(Hz) : 28




站长统计



©2006 HiVi Inc.(USA) All rights reserved.

[fjhuerta]

I'd need to mount it on baffle and take a measurement. Or, have infinite baffle measurements of it. I don't think I've seen them on line... I'm not sure they exist. Do you have a link to a PDF file for it?

[xumbug]

Hi Javier,

Here is the link - www.swanspeaker.com/product/htm/view.asp?id=60

Regards,

Stuart

[xumbug]

Hi Javier,

Forgot to mention, when the language pack installation screen pops up just click x and the file will load up!

Regards,

Stuart

[mdrake]

Very nice design!! What is the software you are using to design the speaker?

Matt

[fjhuerta]

Hi,

I did it all on LSPCad 6, JustMLS, the KHF Tool.... the Edge baffle step compensation and the XLS Spreadsheet by Paul Verdone for finding diffraction effects.

It's still my favorite speaker. After building a couple more designs (including Zaph's Dayton RS 3.5 way), I find the Neos have the best midrange and highs of them all. They don't call any attention to themselves - they are smooth, unfatiguing, clear, detailed... I'm currently using them with a McIntosh MC-240 tube amp, and they behave beautifully with them. I used them with a Channel Islands Class D amp, a Rotel RB-1070... even a small T-amp. No problems whatsoever. They are the best drivers I've yet used.

I'm currently building a Jed's Tombstone clone, with an Usher 8137A, TB W3-1335SBs and Seas 27TAFN tweeters... if they sound as good as these ones, I'll be extremely happy.

[brianpowers27]

I am looking at doing a similar project using 2x rs225s8 in parallel.

• DO you suppose that this would provide a good sensitivity match?
• With your xo, will the BG NEO8 reach 110db?

[fjhuerta]

2 RS225's would be, I think, a bit too sensitive for the Neo8, perhaps 1 dB or so (which could be "fixed" by using a lower gauge inductor in the woofer circuit).

I've actually thought about changing this to a floorstander two woofer system. I'm sure they'd sound nice.

[brianpowers27]

I am debating the possibility of building a very robust tower and was wondering specifically whether or not the neo8 would handle high volumes. I don't listen at rock concert volumes often but I would like to have the ability to take these speakers to smaller venues.

I am guessing that I may gain some sensitivity because I would be using the neo8 in dipole mode. I realize that I am in for a treat trying to equalize the low end. I also need to decide on a baffle size. I am seriously wondering whether or not this may be asking too much of a single neo8 per side.

Could you tell me whether or not you have tried these in a situation where they were really cranked?

[fjhuerta]

It'd seem I'm stuck in the past. In some ways, I am. I was fortunate enough to get back the first speakers I ever built and the Miniliths... for free!

The guy I sold them to got a Bose Lifestyle system, so he didn't need them anymore. Heh.

Anyway, I compared the Miniliths to:

https://www.htguide.com/forum/showthread.php?t=37532

Just to give you an idea, this is the FR, in room of the Miniliths (aqua trace) vs. the Megaliths (red trace).



So, apparently, the Megaliths' power response is far better, the bass hits far lower, and the midbass is less bloated.

Why on earth, then, do I still prefer the midrange and the high end of the Miniliths?

It just doesn't make sense. The Neo3 & Neo8's FR is a lot more ragged. I'm using 2 TB W4-1337's instead of a single Neo8, and two RS270's (!) vs. a single Seas 8".

And, know what? I could live perfectly happy with the Miniliths instead of my huge towers. All I'm missing is the deepest bass (which is far better on the big towers).

The Neo8 and Neo3's are champs. I wasn't wrong when I said I preferred this design to any other speaker I owned. 4 years later... I could say I still do. Wow.

[Jonasz]

In my ears the Neo3 used right is one of the best sounding tweeters out there, especially considering the very reasonable price. :P

[fjhuerta]

Yeah, the Neo8 and Neo3 are... different. I hate to use this term, but definitely, they sound "fast". As in "transients are incredibly sharp", waaay faster than my cone drivers. And that is with the Neos in an enclosure, I can imagine in open air they are even... well, faster.

One thing my cone speakers beat the living dynamics off the Neos is, well, dynamics. The Neos can't go very loud without audible stress.

[dtaylo1066]

Minilith

Do you have a schematic of your final enclosure for this design?

[Andres Silva]

Hi (hola) Javier,

I live in Mexico City too, If I write in English is because this is the languaje HTguide forum. Please tell me the amplifier you use with your minliths? The minilits works better with tubes or solid state amps?

Thanks and saludos,

Andres

[5th element]

Well the neo planar drivers are some of the best measuring drivers within their pass bands too. I wouldn't say that the frequency response of the miniliths is 'ragged' we're still talking only +-2dB from 400hz and up. There's nothing wrong with the minilith design compared to the megalith except for maybe the bass driver running a tad hot.

If you prefer the midrange/treble from the miniliths then I'd just go with it, they have every right to compete with and perhaps exceed the performance of the megaliths. Each of them handle the midrange and treble in quite different ways, it isn't really a surprise that you have a preference for one.

[JonMarsh]

Javier, it's likely about the difference in distortion products. That, or some aspect of the power response that sounds more natural. As 5th notes, there are reasons the Neo3 and Neo8 are well regarded.

[fjhuerta]

Funny how these things work. This thread was digged up a couple of days ago, and I modified and re-painted the Miniliths, to better fit the room they are in now. And yeah, there's a circuit change involved, and yeah, to my ears, they are better than ever

All of the changes have to do with the midrange - woofer interaction. The P21 is an excellent driver, and its bandwidth is quite wide, so it needed something faster than a 2nd order electrical.

It's interesting that I've built at least 5 more designs after these ones, but I always come back to them. I just saw how many crossover iterations they've been through - 5. IT seems that everytime I learn something new, I mod them - but no other designs. I suppose that, after all these years, I wasn't wrong, and I really do love the Neo drivers. I'm listening to Gaucho right now, and Donald Fagen has never sounded better. :thumbup:

I think it's time to properly document these speakers. I know the P21 is no longer available, but the tweeter - midrange crossover can be reused with other drivers.

Tomorrow, hopefully!

[fjhuerta]

Sneak peek: I took off axis measurements from 0 to something like 80° in 6 steps. Here's the result. I like what I see.

[cjd]

This makes me very excited to get to the project I'm collecting parts for that will use the Neo8 as a mid. I won't be using the Neo3 though.

[fjhuerta]

Hi C,

Actually my latest redesign of the x-over is based on what I've been able to learn about power response and off-axis response. The Neo8 works pretty good in this regard. I *think* (correct me if I'm wrong here) that the driver, being so slim and yet so tall helps smooth its horizontal off axis response a lot when compared to a standard cone midrange. That, and the fact that it simply sounds so great - if I were asked about this design, I'd say I love it because of the Neo8.

[JonMarsh]

Low distortion midrange drivers are crucial... the ear's pretty sensitive in that region.

[5th element]

I can only echo what Jon has said. I was really happy with the way my W15CY001s sounded and then I swapped that out for the B&W FST midrange unit.

At normal listening levels the distortion looks like this.



Which is ridiculously low and turning it up beyond that, to what I consider loud, only really increases the second harmonic up to a flat 0.1%

Perhaps you should perform a sweep of the Neo8 + Neo3 at your normal listening levels and compare it vs the megaliths, it might show up something interesting.

[dtaylo1066]

How about the Neo 10 in an upgraded design? Looks like BG is using it in a new commercial speaker they offer and it is flanked by the Neo 3's. Looks like a dipole.

[dtaylo1066]

My bad. Their new Radia speaker is an MTM with two Neo 10's around a Neo 3, then filled in below by 6.5" bass unit.

[rhubarb9999]

Any updates to this? I have a Neo3 and Neo8 .. looking for a woofer (hopefully something that is still in production)

[boudy]

Do you have a schematic of your final enclosure for this design?

I'm also would appreciate this information. A list of key dimensions would also work if a drawing is not available.

Thanks and good work!