Bohlender & Graebener transducers

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Experience with RD75 and Neo8

I have some experience with BG drivers.

The Neo8 has some interesting characteristics, but also some that make it difficult to work with, particularly in a smaller design such as you propose.

Here are some plots on axis and off, mounted on a 2' X 4' baffle:

An externally hosted image should be here but it was not working when we last tested it.

In a longer line array, the on axis peak at 13 kHxz is ameliorated to a degree.

Used in singles, the Neo8 has very little vertical disperion at high frequencies (imagine trying to make a 6" dia tweeter - it would beam like a searchlight above 5 kHz), so the speaker would have to be a just the right listening height. In multiples in a line array, it is more useful and less critical of listening position, IMO.

The bigger B&G drivers make some truly wonderful midranges, say running an RD75 from 600 Hz to 5-7 kHz, for example. Stunning on classical music, to say the least.


Well, I was planning on using a NEO8 up to 5.5kHz and then crossing over to a NEO3PDRFP above that. Maybe something like that is what you're looking for. Unfortunately I've got some of the drivers (probably going to use a focal woofer for the base), but it won't get started until I finish off my current speaker set, so I don't have any actual experience...
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I do not understand your objective. You state this is a minimonitor, and from this i must presume you are using a 5.25" or 4" midbass. You want to cross around 1.2-1.5khz fom mid to neo8, and then 5.5khz to neo 3? This is what i must presume with lack of further description.

What is point of this? Their are pleny of adeuqate 5.25" Mids available that exhibit excllent properties into 2-2.5khz range.


I personally wanted to see what these ribbons could do, so using the neos would get good top end and go down to say 1k. I know many good woofers are capable of producing excellent sound there. The point of my exercise was to see what the BG planars sounded like. Who knows, maybe I'll like them better then a cone driver, maybe I'll hate them, but there's one way to find out...
My initial experiments with the neo8 show that it's off axis performance (virtical) really isn't as bad as I was lead to believe (or maybe my standards aren't as high as some). But I feel confident that I can do without a "super tweeter" for my needs and where it'll be used (smallish room). Probably soon I'll couple them with small woofers (6" to 8") to see how that sounds.
I've heard of someone in the partsexpress forum who crossed them over at 700Hz & 8kHz, but I'd cross them over around 6-7kHz. They got alot of praise as midranges. I'm still playing around with mine to find good xover frequencies, but 700Hz sounds nice. I'm not dead set on a high frequency, but probably 7k is where I'm going to try first, I just haven't decided on what tweeter to put above it, the NEO3 can go down to something like 2k, so it'd be a waste to use it...
NEO3 is $40. The Vifa =XT25 is $60. I'd be willing to try the NEO3 if it is a good tweeter ....

So something like this:

NEO3 6khz- >20khz ($40)
NEO8 700-6khz ($60)
Peerless 6.5 ~60-700hz ($40)

($140 for drivers per speaker) hmmm i guess your right ... it is getting pretty expensive.

I'm just thinking outloud here ...
Thinking out loud as well. I'm sure the neo3 would make a good match, but I'd rather find something that didn't go as low, for it feels like a waste, if you understand. I was thinking of pairing them with an 8"-10" since they only have to go to 700Hz. If anyone know of a good tweeter to cover from 6k or 7k upwards, please do tell. I'd like to use a planar or ribbon or what not to keep with the theme, but some of those get mighty expensive...
I've heard of someone in the partsexpress forum who crossed them over at 700Hz & 8kHz, but I'd cross them over around 6-7kHz.
I`d try to cross them even lower. As higher You cross as more lobing (and beaming) problems You`ll get in the crossover range. I think 5kHz would be reasonable.
Still better: to avoid the additonal tweeter at all if possible.
The Neo8 appears to work fine without.
If have had some quite similar experiance in combining a Strathearn ribbon with a Visaton planar tweeter and finally settled slightly above 5kHz. Unfortunately the Strathearn did not so well without tweeter.
BTW.: Does the NEO8 really go for "only" $60 - I wouldn`t consider this expensive for a good planar mid/high driver!?
I´m curious too about how good it`s actually and without tweeter.
At partsexpress it's $60 us and at css it's $100 cnd. I've tested without a tweeter and it does sound very good to my ears, but I would like to try it with one to see. In the midrange it sounds very nice indeed. Although it's hard to find a suitable woofer to pair these with.
I thought about trying these out as computer speakers since they could be built with a really small footprint or even tacked on the wall. I didn't because the response doesn't look all that great on paper (maybe thats a feature though?), I didn't know much about tuning a response with them, and the woofer/sub under the desk would be playing an awfully large part of the spectrum leading to really bad imaging and just general non-coherent sound I am thinking. maybe in the future somebody will sell acoustically transparent countertops....

Hi folks
Sorry for my rudeness for not having responded earlier.
You are all 100% more experienced in matters of speaker design
than I.
So I thought it best to read your replys and ensuing conversation.

I was really toying with using these units as a near field setup to
sit with my pc.

The speaker side of things would then just be a start,if I was
to search out a good level of fidelity in this area.

Such a project is in my 'think about it later' cupboard for now as
My Headphone transducer project is on the move again at present.


Setmenu:eek: :D
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