B&G's for mids?

I have a dream; to build my own dipole speakers with 3-4 x 12" GR Research servo's per side for basses, and Magneplanar 3.x ribbons for highs. DEQX will handle the crossovers and level/phase corrections.

For the mids I have been thinking of B&G's, and I have a few questions for you guys:
- What would be the best B&G driver to fill the gap between ~200hz to ~3khz? Line of NEO-10's, RD-50, or what?
- Can any of B&G's actually go down enough for GR's? NEO-10 are claimed to play down to 150hz, but on the other hand, I have read discussions that maybe they should be crossed over near 300hz or such.
- What's your opinion on this whole idea over all; would it be a good combination or not? Are there some probable pitfalls to be aware of?
 
NEO 10

Attached is the response of the NEO 10 from Parts Express specs.
This is from 1/2 meter away, and it looks like pure dipole, no baffle area around it.
If you build an array of these with maybe some more baffle, that out-of-phase cancellation will come in at a lower point than 1kHz, and you would still get that airy dipole sound if you manage the back wave.
Pitfall: The upper peak has to be dealt with using a trap of some kind. I have two NEO 8s on either side of a tweeter and they have a similar peak. They will be in series and I was able to make one filter for both, but something has to be done because it adds a raggedness to the otherwise exemplary sound.
 

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If you haven't obtained the GR's yet, I encourage you to hold off and do some more research on the low frequency section - those will sound way too schlubby compared with the BG's.
More opinion:
Bass gets cancelled out in most any dipole system because it is non-directional and the out-of-phase sound from the back radiates spherically along with the sound from the front. Ask the guys here to suggest a musical, well-damped combination of woofers and box(es) that is the equal of your mids and highs.
 
Pitfall: The upper peak has to be dealt with using a trap of some kind. I have two NEO 8s on either side of a tweeter and they have a similar peak. They will be in series and I was able to make one filter for both, but something has to be done because it adds a raggedness to the otherwise exemplary sound.

I think that DEQX could handle that quite well?
 
If you haven't obtained the GR's yet, I encourage you to hold off and do some more research on the low frequency section - those will sound way too schlubby compared with the BG's.
More opinion:
Bass gets cancelled out in most any dipole system because it is non-directional and the out-of-phase sound from the back radiates spherically along with the sound from the front. Ask the guys here to suggest a musical, well-damped combination of woofers and box(es) that is the equal of your mids and highs.

Thanks for the comments, paulfx!

I have tested many many high class box subs, and on my opinion, none of them matches Maggies well enough. I don't know the word "schlubby ", but pretty much all box subs have sounded too slow and boomy for me. They just didn't disappear to the sound stage. And it might also be quite problematic to match dipole to the monopole, since their acoustical behaviour in the room is so different. So dipole is surely the way to go for me.

The best box sub (below 2k$ atleast) that I have heard with Maggies was Rythmik Audio's DS-12, using GR's 12" servo driver. It was the only one that was even close to the speed and accuracy of Maggies, so it might be a good choice for dipole setup also. I also have read many many very positive reviews for Maggies & GR's. So I was thinking that if it can match Maggie's mids, it might also be a good option with B&G's.

But; what's your suggestion for the better bass driver to match B&G's??
 
If you haven't obtained the GR's yet, I encourage you to hold off and do some more research on the low frequency section - those will sound way too schlubby compared with the BG's.


I will have respectfully disagree here. The GR servo woofers sound fantastic, but as is always the case, proper adjustment and integration with the other drivers is the key. I have heard them many times and they were always fantastic. I was very close to using them, but in the end, stretched to a 4 way configuration and run the Rythmik 15" servos under 60 Hz.

Also, if you are going to use any of the Neo series drivers(which I highly recommend), I would recommend to NOT solder them. Use push on terminals. You can solder those to the wire if you do not have a good set of crimpers. Or do both!

Greg
 

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Yeah, it seems that NEO-10's really are a good match for GR's.

But how about RD-50? Can it go well down to 200hz, if steep (48 or 96db) crossovers from DEQX would be used? Twelve pieces of NEO-10 is quite expensive setup anyway, and two RD's could be bought for under half of the price of NEO's.
 
No idea on the RD series apart from what I've read I'm afraid. It depends how wedded to the (semi?) line source format you are though. In terms of radiating area and sensitivity you wouldn't need six BG 10s to equal one RD-50. In fairness though, you would probably want to use tweeters with the BG 10s, which is an additional cost.
 
Yeah, it seems that NEO-10's really are a good match for GR's.

But how about RD-50? Can it go well down to 200hz, if steep (48 or 96db) crossovers from DEQX would be used? Twelve pieces of NEO-10 is quite expensive setup anyway, and two RD's could be bought for under half of the price of NEO's.

There seems to be some disagreement on how low to run the RD series. BG says to 200Hz is OK and StigErik runs them(RD75) that low in his system, but other guys out there try to get off of them by 500Hz or roundabout there. I've never personally played with any and only heard them in Genesis designs and a few other DIY efforts. Both designs used super tweeters in addition to the RD.

Greg
 
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How did you like them, Greg?

If you mean the RD drivers, it's been too long to make a fair judgement. At the time, I was in love, but the more we learn and design, the more critical our tastes become.

If you mean the Neo10, after testing a dozen or so drivers for mids on my project, the Neo10 won. If you are going passive, they are not the easiest to use due to their rising response, but on the other hand, crossovers behave much more as theory would suggest due to their flat resistance and inductance profiles. For active, there are few mids I've heard that top a well implemented Neo10. The newer Neo8-S version is also nice and can play quite a bit lower than the old Neo8. I just used one in a prototype for a new studio monitor and it's working well so far. Crossing at 425hz from the Discovery woofer and 3KHz to the OEM Raal.

Greg
 

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It seems to me you are missing a link here, woofers! It seems like you are trying to go from mids to sub-woofers. I have the Neo-3's, Tang Band W4-1337SD 4" titanium FR's for mids and a Velodyne 15" sub, and was hoping to go dipolar, but have come to realize that for now I just don't have the room or budget. While I can't pursue my dream of bipolar, I am working on a kind of shoestring tri-amp system using a DBX-234, mostly switching off the amps I use in my proletarian HT system (that uses NHT Super Ones), I'm figuring out what 7"-8" woofers I'm going to use as woofers, and waiting for this Chinese 10-watt Class A amp for the 3's.

When I was still dreaming bipolar I had decided on Nelson Passes slot woofer idea, The Slot Loaded Open Baffle Project Article By Nelson Pass and had even stumbled on some place selling surplus drivers mad cheap that would make 8-12 drivers quite affordable- Speaker Stuff. Sir Pass originally used 6 8" drivers a side, but I figured using 8 of those 10" Infinities would only be 100$ a side and probably go deep enough to eliminate any need for a sub for just music (for HT it would still be good), maybe going with the 6-8inchers a side would be better with a sub, but that site has some reasonable offers there too. Since I don't have room for OB's I'll be putting those 8inchers in 1 cu. ft. sealed enclosures I got cheap until I can work out some transmission lines to put them in. Not my dream system, but not too shabby for a blue collar stiff like me. Hey with the powered sub, I'll be beyond tri-amped...
 
My vote would be for the RD75 ribbons. As mentioned, Stig Erik uses them and loves them.

Why should I use separate "woofers", if GR's basses can go up to 300hz (I surely would not call them subwoofers)

AFAIK, if used with the servo amps, these can only go as high as 120Hz. So if you say 300Hz, do you mean without the servo feedback? It would be great if they did go that high with the servo feedback, so I'm wondering (and hoping) that my information is incorrect. Please tell me more.

Thanks,
Deon
 
Those who have listened to both the older tech. RD series and the newer Neo 3/8/10 series seem to favour the latter. I've not heard the RDs, but own all the above Neo drivers, which are excellent. The Serenity Super 7 I linked to earlier uses four Neo 10s crossed over at about 250Hz to the GR servo 12" drivers, which are driven by the matching Rythmik plate amp. Yes, the servo is active. No reports of any integration problems. One thing that might be significant depending on your choice of power amplifier; four Neo 10s run series/ parallel have a sensitivity of 96dB vs 88dB for the RD75. Power handling should be quite a bit higher than one RD too. No axe to grind though- as long as implementation is good I'm sure the RD series sounds great- too many positive experiences from users for it to be otherwise- and they will run low enough to meet the GR 12" drivers, depending on how loud you want to go. For the Neo 10s (depending on how many you are using per channel) and the RD75, the practical crossover range is the same, from about 250Hz and up. Either way it'll be a great speaker system!
 
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