With planars, how low can you go?

Anyone know about the mechanics of this technology with respect to low frequencies? If you put a Neo8 type device in a 2-way, does it need a high-pass filter? It takes around 100uF capacitance to meaningfully shunt the low-end signal. Will low-end output be highly distorted and loud... or highly distorted and inaudible? Will the life of the device or output SPL be reduced without a filter?
 
Anyone know about the mechanics of this technology with respect to low frequencies? If you put a Neo8 type device in a 2-way, does it need a high-pass filter? It takes around 100uF capacitance to meaningfully shunt the low-end signal. Will low-end output be highly distorted and loud... or highly distorted and inaudible? Will the life of the device or output SPL be reduced without a filter?
Yes, you most definitely need a high pass filter. The clearance btw the magnets and the diaphragm is very small...1mm or less. Planars also have very high distortion lower in their operating range. For legit BG neo8, I would not cross any lower than 600Hz if you want reasonable distortion and enough headroom for high output levels. For the PE models I tested 800-1000 looks better. They may be a copy of the BG, but are certainly not exactly the same, based on my measurements.

Greg
 
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Hi wout31, so which the correct measurements, this post #5 or post #3? Seems the THD measurements are different.
Both are correct, different set of the same model have different measurements due to small building differences. Quite normal.
Plus measuring with sweep or single frequency gives different results due to interference in the sweep. Single frequencies give better numbers.
 
Hi WrineX, I’ve seen that you’ve made both the ESL and planar magnetic (PM) panels. Do you always find that the ESL have lower distortion?
To me no, but it also had to do how well you make your ESL i guess :) i made better planars then i did ESL's :) i think.

also not really comparable. unless you go big. my tweeter are 1/6 the size of many esl variants. while comming close in distortion. give that same planar 6 times more surface area and im sure it is as good if not better then the ESL.

here is a larger midrange distortion measurement @ 96 dB @1 meter, (amplifier could not deliver more back then)

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and here when normalized

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so in the used bandwith 300-4000hz +- 0.12% THD. but its 6 db louder then the quad test though. so i might even had lower Thd then the quads there.

by the way in that test they used both left and right speaker..... thats unfair :) so my panel is doing more work :(
 
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Does this membrane vibrational modes also occur with ESL membrane? Since it’s driven more uniform across the ESL membrane area
AN ESL has a resonance as well, but not the breakup thing. since its driven on the entire surface.
When a planar magnetic has coil almost everyhwere on the foil these breakups move up and above the audio range (i do this in tweeters, not useable in bass panels and is related to the width and strength of the magnets used, and the distance from trace to trace.)