QDN A 2-way BG Neo8 and Woofer Combo

[ligs]

Having acquired a pair of used BG Neo8 PDR recently, I am anxious to audition this 8-inch planar mid-tweeter. I “Googled” at several designs including Miniliths, lou’s Neo8-Neo3-RS225, as well as MSaturn’s Usher 8137 Neo8-PDR. In addition, there were several sketchy descriptions of using NEO8 in a 2-way setup but without detailed crosssover schematics.

Because I can not wait and I don’t want to buy more drivers so I just used a QDN (quick and dirty and non-critical) approach. Here are two pictures of the prototypes.

Neo-8s are mounted in the front of the enclosures of Radioshack Solos with a front of about 5.5-in x10-in x6-inch deep. The back of both enclosures is open. In the first picture the woofer is Klipsch 6.5 inch buyout. In the second picture the woofer is AR 10 inch (savaged and refoamed from AR –48). A 1.8 mh (14 awg air-core) and 32 uf LC provide the low pass to the woofer. A series 3-ohm and an 18 uf RC high pass is for the Neo 8. The use of the shallow slope highpass makes the transition from the low to mid less critical, like some of the vintage AR1 , 4 and KLH speakers in the past.

I don’t know it is because of Neo 8 or because of the open back, human voices are very natural and detailed. Neo 8 is indeed somewhat directional but when you are in the zone there is a lively image unlike anything I heard before. BTW, Klipsch 6.5 in the vented enclosure (savaged from JBL LX 22) produces just as much bass as the 10 inch AR in AR-28BXI enclosure.

Comments and recommended crossover modifications are highly welcome.

[ligs]

Let me use a picture to describe the XO of this QND. The basic goals are:
1. let BG Neo 8 PDR reproduce most of the mid and highs. They are known for having the panel speaker-like sound at a fraction of cost.
2. Use a woofer to augument the midbass and bass.
3. Large overlap of the drivers so the exact crossover point is not critical.

Beacuse the Neo 8 is operating in a dipolar fashion, smooth integration of woofer with Neo 8 will be largely out of my ability anyway. By slowly blending in the Neo 8 the crossover will be less critical than the one with sharp cutoffs on either side of the XO point. Some vintage speakers are quite listenable due mainly to the large overlap of the drivers.
With 90db plus sensitivity of Neo 8 , this midrange-tweeter will do largely what a Econowave will do for the high end.

Please comment of this assumptions and illustions that I suggested. I am thick-skined enough that I actually welcome some negative comments

BTW, I am highly impressed by what a tiny K-6.5 will do in this K 6.5-Neo combo in a 400 ft2 room. There is more bass in K 6.5 than an AR 10 inch woofer and it is highly musical.

[jeff_free69]

I've been on the edge of picking up the Neo8's before the feb flyer sale expires. Some "QnDX" (Quick n' Dirty expermentation) of my own will help justify the endeavor! got some old morel 8's in a vintage 1.5 cf...

but I'll probably try a hybrid before hatcheting the backs open, and XO the Neo8 lower / steeper.

BTW your XO picture indicates "neo 3" you meant 8 , right?

[ligs]

Jeff Thanks,

Opps. Sorry about the confusing. It supposes to be Neo8 PDR not Neo3.

Bohlender Graebener Neo8-PDR Planar Transducer is on sale at PE.
http://www.parts-express.com/pe/show...number=264-713

For about $ 120 a pair you can probably crossover a pair of them with any decent 4-10 inch woofer without too much work. You can use simple open back enclosures to house Neo8 and just seat them on top of the woofer enclosures. I often wonder the attractiveness of Econowave is partly due to the lowering the W-T crossover frequency so you have a more even dispersion of the midrange. The lowering of THD of the tweeter at the lower part of to its operating range is another virtue.

Now the question of intellegibility of speech. I can hear clearly a pair of K 6.5-Neo8 placed downstairs while I do my listening upstairs. Of course Neo 8 does not give you the sparkling highs a metal dome would do but it rewards you with a very big sound and substantially more midrange details(intelligibility again) than than a typical W-T 2-way.

[MSaturn]

Per using the Neo8PDR in a passive dipole format: I don't recommend it. I also don't recommend its use as a tweeter - pair it with an ND16 at 5-6Khz.

The way I ultimately ended up using my Neo8s was in a dipole passive/active setup - the ND16 and Neo8 have a passive crossover, then the Neo8 is crossed to JAMO buyout drivers actively. The EQ is quite vital in eliminating some weirdness caused by dipole use/the Neo8's FR curve.

[ligs]

Can you share more of the experience about integrating Neo8PDR with a woofer.

I used to like Radioshack's LX-4(monopole Linaeum) more than LX-5(dipole Linaeum) I thought it was due to the problem with the breakup mode of LX-5 woofer. In either case the crossover is extremely simple, there is an inductor to the woofer(Dick Olsher added a small inductor to the woofer in LX-4 and called the modified LX-4 loudspeaker to be the sonic bargain of the Century) And for the Linaeum tweeter there is only a single capacitor for both monopole or dipole versions.

http://www.blackdahlia.com/tipindex/Tip__3/tip__3.html

[ligs]

Per using the Neo8PDR in a passive dipole format: I don't recommend it. I also don't recommend its use as a tweeter - pair it with an ND16 at 5-6Khz.

The way I ultimately ended up using my Neo8s was in a dipole passive/active setup - the ND16 and Neo8 have a passive crossover, then the Neo8 is crossed to JAMO buyout drivers actively. The EQ is quite vital in eliminating some weirdness caused by dipole use/the Neo8's FR curve.

You are quite right. Following your suggestion I have turned 2-way QDN into 3-way. While QDN 2-way sounded pretty decent, it had a certain hardness/thickness probably due to the on-axis peak above 10k Hz.

For the added tweeter I used an Infinity Perfect 6.1 1-inch CMMD tweeter. According to Zaphaudio, it has fairly benign distortion characteristics. http://www.zaphaudio.com/temp/Infini...fect-TW-HD.gif and is definitely not shy in the 10 to 20 k Hz range.

For the 3-way XO, I used a 2.7 uf cap and a 3-ohm resistor for the high pass to the tweeter.
I added a 0.15 mh awg aircored inductor to BG Neo 8 to roll off its high range.

With this 3-way, the slight thickness is gone. Infinity tweeter fills in nicely the slightly subdued top octave.

I listened to Enya’s Water Mark CD using the new 3-way speakers. This album is very thick in texture. On typical speakers it tends to sound muted or congested. But with this Neo8 PDR 3 way it sounded nicely delineated and the vocals were so clean I ended up in listening at much higher volume than I normally did. These speakers disappear pretty nicely in my opinion. BTW, Klipsch 6.5 blends well with the other drivers while providing a surprisingly good foundation for the bass heavy passages.