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Review: Bohlender Graebener Neo10 Planar Transducer

edited February 15 in Hard Data
Bohlender Graebener Neo10 Planar Transducer is up.

Klif's notes: Very non-linear frequency response. Odd things in the unit-to-unit consistency with regards to the distortion. I know people have used them and liked them... I don't see it.  Maybe there's a legit use for them that I'm just not aware of like line arrays (as the marketing indicates). Either way, I can't recommend them for 'standard' speaker applications based on what I'm seeing here.


  • Huh, I was also always under the impression that they were better than that. Good findings. (
  • They are great, and used in one of the best speakers I've ever heard; Dan Neubecker's "Echelons"

    Measurements are not everything.
  • Very true, I really like the neo 3's and 8's which measure with the wicked peak up top. They sound fine with it, trying to take it out usually saps the life out of them. I think eventually I'll end up with some 10's
  • Dan's Echelon used this driver from about 300Hz to 2kHz, and it does perform well in that frequency range, the strange frequency response won't take much to be worked out in a crossover. The unit to unit consistency isn't the best, so you may end up tweaking the crossover a bit with every one you make. Not a big issue if you only make a single pair for yourself, but not very good for anything manufactured in volume.

    The HD results look like some buzzing issues perhaps, but not of much concern other than sample 4, the others are all performing well in the 300-2kHz frequency range.

    For myself personally, the price tag and looks are more of a deal breaker than anything. They don't look very attractive to me, and at USD$370 it's competing with top of the line cone drivers. However, if you're in the market for a big midrange planar, there's not really any competition out there, so the price isn't likely to come down as it's the only product in that niche that I'm aware of.
    I'm not deaf, I'm just not listening.
  • Right.  I stated in the review that I think 300-2khz is the best operating range.  And with a high-order slope and/or some EQ work they could be made to work well.  But, from a "great starting point" perspective there are a handful of things that are just bothersome about the performance.  For instance, if you bandpass it between 300-2khz you're still in the mid-80's sensitivity.  There are many other drivers that could be used within this range with higher sensitivity and cheaper cost.  
  • edited February 15
    Wolf said:
    They are great, and used in one of the best speakers I've ever heard; Dan Neubecker's "Echelons"

    Measurements are not everything.

    Measurements are insightful.  And that insight helps determine applicability.  
  • edited February 15
    Wolf said:
    They are great, and used in one of the best speakers I've ever heard; Dan Neubecker's "Echelons"

    Measurements are not everything.

    I looked up Dan's Echelon's.  Found his discussion about them here:

    "I number of folks asked for off axis measurements. I have some that were taken of the raw drivers that will indicate how the directivity of the tweeter and midrange match, though I don't have any that I saved with the XO in place. The XO point is around 2khz between the mid and tweet."

    2khz crossover.  Which is the recommendation I gave in my review.  There ya' go.  I made a subjective call off objective measurements.  Which just happen to line up with what was used.  So, I guess measurements tell enough.  :)
  • More to the story...

    "Crossover points are at 325hz and 2100hz. The woofer to midrange acoustic slopes are approximately 15db/octave, halfway between second and third order. The midrange to tweeter acoustic slopes are approximately 24db/octave."

    Turns out, my suggested crossover range (derived from just looking at the measurements) was nearly dead-on to what the builder used.  Damn, it feels good to be a gangsta. ;)  :D
  • You didn't believe me? ;)
    I'm not deaf, I'm just not listening.
  • dcibel said:
    You didn't believe me? ;)

    I admit it.  The blanket comment that "measurements aren't everything" caught me so off guard in a "hard data" sub-forum that I went to do research and completely had my blinders on.  It happens.  I apologize.  Next time, just post in huge, bold, red letters.  :D
  • What I didn't like was that you gave a decent driver a bad reputation in your Klif's notes at the top of this thread. That is what made me state what I did. You will find that (like Zaph and Jeff have both found) giving reviews of drivers can give them a bad reputation just by saying you do not recommend them. You should have said at the top of this thread; "Looks usable from 300-2k, and that it would be good in that range." Instead, you stated you would not recommend this driver for normal speaker usage. I'm not saying paint them all positive. Just be careful what you say. Some guy could come along and not use this driver, just because you ultimately did not like it.

    I didn't even watch the video, because I felt you wouldn't paint it fairly saying you saw it as unusable.
  • Well, you really should have watched the video, it was enlightening!
    I'm not deaf, I'm just not listening.
  • I get it.  The cliff's notes was rather abrupt.  But I stated what I did based exactly on the data.  If you had clicked the link you would have seen that my actual review stated the part about being usable between 300-2khz.  
  • I always like ol' Zaph's writeups. Ranked the drivers for FR/HD quality and the ranked for value. The Neo10 may be useable, but at $370 each, you are now in Purifi territory for without question, better sound quality. 
    Don, Donno, or "Hey you" all work for me, But never "Mr Johnson"
  • Yea, and I'm working toward coming up with a way to rank drivers based on cost/performance.  Unfortunately, there's not entirely an easy way to do it.  You have to factor in intent in some cases.  It wouldn't be fair to use the same metrics for a 4" midrange as you would a 4" fullrange because (one would assume) certain compromises were intentionally made (i.e., sensitivity for excursion).  I try to remain as objective as I can; I feel like people ranking drivers without explanation on their exact methods is more subjective than it is objective.  But like I said, I hope to be able to come up with a way to do the latter.

    - Erin
  • I had an extended chat with a very famous designer a few months ago about the difference between hobbyist and professional engineer. The hobbyist sees a driver and wonders what can be done, the engineer starts with an objective and asks how to get there. I generally fall under the latter approach, it turns out.

    Publish the data and your opinion; how people interpret said isinformation is entirely determined by their individual approach. 
    I have a signature.
  • That's a very good point.  I think there's some overlap in your statement, too.  An engineer could see a driver, test it it from a hobbyist POV and not have a specific use but recall that driver later and then use his engineer hat to implement it.  
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