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Old 1st May 2017, 07:20 PM   #21
WrineX is offline WrineX  Netherlands
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OOoh god damnnnnn !


i tried some of the ideas i had about the high freq problem ,for getting the biggest results i used the bass panels since they show the problem over a bigger bandwidth.

these are the measurements up close.

The panel in question:
A bass panel with wires attached like magnepan, magnet width 8.5mm 13 magnets used in total


Picture one:

RED: Plain panel nothing hapened here, it has just wires and a some glue on the mylar to hold the wires.

BLUE:i added strips of gaffer tape to 8 out of the 13 magnets in between the wires really messy just a proof of concept. 62% coverage.

PURPLE: 100% coverage.


Picture 2 is the contraption


Picture 3 measurement of 100% coverage what does the tension do to the freq respionse?


Blue: neutral state
brown: bended state so i stretched the menbrame more then it is now.




That are some cool results if you ask me. still not sure if the same goes for the mid/high drivers but i can guess it does something to say the least.

what else it does is lever out the bass to High frequency response and as well damp allot of crap in the distortion department picture 4 before any of these tests, picture 5 after tensioning and adding the tape. looks smoother,


One thing funny i just noticed , by adding tape i lost around 5 dB, but when stretching i gained 5 db again. so net not much lost
Attached Images
File Type: jpg tape in between.jpg (234.9 KB, 91 views)
File Type: jpg panel tape.JPG (191.5 KB, 93 views)
File Type: jpg 100 tape low high tension.jpg (200.1 KB, 92 views)
File Type: jpg before any of this.jpg (279.3 KB, 90 views)
File Type: jpg after any of this.jpg (266.4 KB, 88 views)

Last edited by WrineX; 1st May 2017 at 07:24 PM.
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Old 1st May 2017, 08:40 PM   #22
WrineX is offline WrineX  Netherlands
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Quote:
Originally Posted by WrineX View Post
One thing funny i just noticed , by adding tape i lost around 5 dB, but when stretching i gained 5 db again. so net not much lost
Hmm i forgot i might bended the magnets closer to the conductors as well so this might not be completely valid
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Old 2nd May 2017, 03:05 PM   #23
lowmass is offline lowmass  United States
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Looks to me like the undriven space between wires may be moving in opposite direction than wires giving the sudden break just above 2 khz.

The purple trace I assume showing with full coverage of the damp tape??

Years ago I remember playing with this a bit. In the end when using larger wider magnets that result in large spaces between conductors I ended up simply making the foil traces full width from center of one magnet row to center of next magnet row. Same as Apogee bass panel. This seems like a waste of signal current in that quite a bit of current in conductor is now centered over the non ideal magnet flux region, BUT it ended up making a small difference in sensativity and a large difference in damping that area. I suspect the foil/adhesive/film combo being a much better impedance match than the tape ( I tryed all sorts of tapes and even thin felt) and seemed to damp much better

With these types of planers if going higher than bass duty it seems best to keep traces small and space between them small to avoid the issue. Problem is now we have very small magnets and a very small field wich means getting diaphragm very close to magnets to work well limiting excursion.

Anyway take above with some skepticism as I left that quest unfinished and its all speculation on my part.
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Old 2nd May 2017, 05:50 PM   #24
lowmass is offline lowmass  United States
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Ha found my notes from years ago on this one. I looked at the magnet flux lines over top of the magnets and thought that a conductor in this area was useless. Then thought having the foil/adhesive over this area was simply damping that region better.

BUT then did some tests. simply holding a wire with DC current and scanning across the magnet array sure enough the wire is not moving perpendicular to diaphragm as we get closer to the center of a magnet. Its moving more at and angle as is to be expected when you look at the magnet field. HOWEVER even though the move is at an angle it is a force thats controlling the diaphragm and it is moving in a direction that works with the wires directly between magnets. This plus a bit of tension on diaphragm and the whole planer surface is being controlled and moving in right direction.

Sooo while there may be some damping of the foil/adhesive/film in effect by wide traces its much more the fact that it is being driven more than you might think.

BTW this was all done using magnets that were 15mm wide with a space of about 5 mm between.
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Old 2nd May 2017, 06:41 PM   #25
WrineX is offline WrineX  Netherlands
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Thx lowmass ! well my spacings are not that big magnets are 8.5 space between magnets only 1 - 2 mm Ill try some wide traces soon then first ill have to check if i am not measuring for nothing the past 3 years maybe you see somethign going wrong.

Here are some tests with the UMIK microphone from minidsp and a DPA 4061 omnidirectional mic. i used my digidesign mbox 2 soundcard as output for both tests and as input for the mic. i did run a loop and, it is as flat as a pancake so the problem is not there.

I must say i run this test on my main computer somehow my laptop wont allow the UMIK and the DIGIdesign soundcard at the same time. i will get a jack to jack tomorrow to see if the soundcard of the laptop itself in question is flat to.


Pic 1 is 30 cm away from a pair of genelec 1019 at tweeter height


Pic 2 very close like 1 cm or something at the tweeter.

i used the calibration file for the measurements with the umik of course !!!

One thing the Huge DIP at 14kHz i have no clue about, it could be anything the genelecs waveguide or something no clue. good thing they both have it so must be there for some reason

what i see is this , the UMik has a big fat peak at around 14 khz and then is almost 10 dB down to the DPA at 18Khz.


OOOOOH an yes i named the measurement 4060 but it is the low sens 4061 mic.
Attached Images
File Type: jpg MICS 30cm.jpg (154.9 KB, 30 views)
File Type: jpg MICS CLOSE.jpg (173.6 KB, 26 views)

Last edited by WrineX; 2nd May 2017 at 06:49 PM.
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Old 2nd May 2017, 07:31 PM   #26
lowmass is offline lowmass  United States
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yes as Bolserst has pointed out the issue up around 15K is likley your measurment system.

I was talking about similar dips in response down around 2-3 khz.

I can tell you this much, my ears tell me theres a huge difference between narrow foil trace only between magnets and full coverage traces unless using panel below 500 hz or so. Much of my work at the time was a full range planer both flat and curved with foil/adhesive/film range from 4 micron each to about 20 micron foil/6 micron adhesive/12 micron film. Also did all designs in pleated similar to Apogee. A wide range and ALL were superior with full coverage traces.
I believe the Bolender planers are full coverage as well.
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Old 2nd May 2017, 07:35 PM   #27
WrineX is offline WrineX  Netherlands
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Bolnder are not if i remember correct , they use multiple traces trough. i must sort out my measuring system.... i am wasting my time playing with this crap if what i measure is not correct. all of my rubanoide adventures stacked esl AMTS etc all for nothing i am pretty pissed cailbrated my *** stupid minidsp. i want my 1000 hours back !!!!!!


i am on the brink of just say to some expensive company heeej yout got a mic thats calibrated >? (DPA b&K etc) telll me the price and recalibrate it and i buy it. since all the time i spend with this is useless if it does not say anything ! i might as well be the guy that says well it sounds nice so it is good. i dont want to be that guy

Last edited by WrineX; 2nd May 2017 at 07:39 PM.
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Old 3rd May 2017, 12:20 AM   #28
lowmass is offline lowmass  United States
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well I wouldnt say all your past work is useless. There maybe an issue with measurment accuracy BUT not nessasarily measurment indication. Meaning that if there is a response upset the system may not be telling you exactly whats going on but its still telling you enough to know basically whats going on.
Most of the time we are trying to overcome a basic problem and just getting ballpark indication of it is enough to goto work on the issue. This is perhaps 90% of the work. from there if we want to refine things to some higher degree then of course we may need calibrated instruments.
The vast magority of your work is still useful info if interpreted well.
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Old 3rd May 2017, 01:46 AM   #29
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Quote:
Originally Posted by WrineX View Post
.. you mean like this tweeter from Vifa?
Yes. That would be a good HF reference for the top octave. If smoothly countersink mounted in the middle of a 1m diameter board, you can then measure directly on-axis and window out the edge reflection to ensure minimal ripples in the response.

Quote:
Originally Posted by WrineX View Post
.. the mic, i got a UMIK with calibration file, and also got a home made uncalibrated panasonic based capsule. wich i think might be the same as in the umik. if i swapp them out they are almost the same. i do use the calibration file here it is as attachment.
I posted calibration data for a group of 7 panasonic mic capsules a few years back.
Image Request: AMT / Heil diaphragm.

I took your data and overlayed it with my data in dashed black line.
You can see that above the peak in the response, all my Panasonic capsules roll off sharply. The calibration data you received has the response flatten above the peak. I could be wrong, but I would guess that the true mic calibration data should follow something like the red dashed line I added above 10kHz.

Quote:
And here a clean measurement of a simple esl i used 2 different amps both match 100% if i change out to external soundcard or change laptop results are exactly the same.
That is a fine measurement there, showing well the natural +6dB/slope of an unequalized ESL. Getting the same data from different sound cards helps answer the question of whether your soundcard and/or driver file are part of the roll-off problem. Looks like they are not
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File Type: png Wrinex_mic_trends.png (101.4 KB, 33 views)
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Old 3rd May 2017, 03:12 AM   #30
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Quote:
Originally Posted by lowmass View Post
...my ears tell me theres a huge difference between narrow foil trace only between magnets and full coverage traces unless using panel below 500 hz or so.
Thanks for sharing your experience. I've often wondered about this aspect of planar magentics where there is often a significant portion of undriven diaphragm area that is just "along for the ride".
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