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Dr Mewlon 28th April 2004 12:51 AM

B&G Planars
Ever since listening to some outstanding Quad57 speakers rebuilt by Wayne Picquet, I have been wondering if it was possible to expand the sound stage effect of my existing speakers.

Over the weekend, I found the Bohlender Greabener line of planar magnetic speakers. I am considering purchasing two of the 8" planars ( or 28" columns ) to be installed as dipole speaker units set further to the left and right of my existing KEF 104.2s. Anyone tried Augmenting Existing speakers with any success ? Or, do I just muddy the overall response with time delays and phase shift patterns ??

B&G information:


bzdang 28th April 2004 03:27 AM

I bought a NEO8PDR to mess around with, and was a bit disappointed with it. I added it to a fostex full range driver which is mounted in a back horn. It's polite, but vertical dispersion is narrow, which is no surprise but it matters more than I expected it to. Horizontal dispersion is quite good, off-axis freq.response is good, on-axis it has a peak that bothers my wife more than it bothers me. It is perhaps more of a midrange than a tweeter, it does go fairly low without evil resonance, but highs don't have enough realism for either of us and I'll try a dome tweeter next (I imagine hearing my horn mentor groan in dismay).
The regular (non-PDR) unit and the long columns have narrower horizontal dispersion, from what I read, suggest you take that into account if choosing to try one.

ashok 28th April 2004 12:40 PM

Neo 8 with Neo 3 ?
Hi Doc,
I sent you a message when you first posted the message.
I forgot to mention that the sound is not very bright or sharp like high end tweeters but it certainly is nice (to me). Some people have used a planar tweeter ( like the Neo 3 or possibly the PT-2 variety ) to extend the HF end. I have the PT-2 but have not had time to try the combination.

Because it is low priced you could experiment with it and a bass driver as I mentioned. The Neo 3 can always be added later if you want to. I would recommend an active crossover . It's much easier to fiddle with levels and crossover frequencies ( and slopes).

goudey 28th April 2004 12:43 PM

I also like the sound of a good electrostatic speaker. The neo8pdr is a good driver, and can give you a similar sound, but...

The neo8pdr has a peak between 10k and 12khz that needs to be notched.

The neo8pdr is not a tweeter, response falls after the peak.

The neo8pdr needs a tweeter, and a dipole arrangement with the neo3pdr tweeter is a bit of a problem (in my view) because the neo3pdr has been discontinued (only the non-dipole model with a back-cup remains in production, as I have been informed).

goudey 28th April 2004 03:30 PM

Addressing the question "Anyone tried Augmenting Existing speakers with any success ?"

Adding a high frequency driver to an existing system generally requires a "system design" approach just like building from scratch. It is best to have measurement capabilities, but there is always the possibility to get lucky.

I have successfully replaced the tweeter of an existing system using the neo3pdr dipole driver. The new tweeter sits on top of the original speaker, along with its own crossover. The speaker now sounds much more like an electrostatic, a tremendous improvement.

Adding a neo8pdr would be much more of a challenge, but with potentially greater payoff.

Regarding the neo8pdr driver, some report good results without adding a tweeter. Some report not needing a notch filter to treat the response peak at 10k-12khz. This seems to be "listener dependent". I have tried the neo8pdr with and without the notch, and with and without a tweeter. For me, the "electrostatic sound" requires the tweeter and the notch.

capslock 29th April 2004 09:08 AM

It should be possible to take off the back cup according to Darren.

goudey 29th April 2004 12:11 PM

Regarding the dipole version of the neo3pdr:

I have exchanged email with both Parts Express and Bohlender-Graebener

According to an email I received from Parts Express,
"Yes, the 264-714's were discontinued (by the manufacturer), ..."
"Yes, the 264-735 is exactly the same element, just with a plastic rear housing attached to the back. It CAN be removed, though it is a little bit involved. At the time I was informed that BG was making the switchover, I immediately foresaw a problem for the "dipole" crowd. They assured me that the back cup can be removed if necessary. I've played around with it, and yes, it can be removed, though it will take a little bit of prying."

According to Bohlender-Graebener:

"As far as the NEO-3pdr or any other NEO-Series driver is concerned, they are all current and in full production. The particular part that Parts Express has probably identified to you as no longer being available is more than likely the one that included the faceplate or the raw driver that does not come with the back cup. Therefore the standard NEO-3 or NEO-3pdr comes with the back cup attached and if you need a faceplate that will be a separate part now."

For a design using both the neo8 and neo3pdr check out:

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