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-   -   I cant reach above 15Khz on my planars (http://www.diyaudio.com/forums/planars-and-exotics/307259-cant-reach-15khz-planars.html)

WrineX 30th April 2017 05:20 PM

I cant reach above 15Khz on my planars
 
Still playing with the rubber magnets, and i need some help! maybe others can shine a light on it. i cant seem to reach over 15 Khz and apparantly the SMGA did not either

https://youtu.be/yYtv1HMkFhU


I used a laminate of 12 mic poly 9 micron alu

i get the same results with 3 mic poly and 40mic alumnium tape. 3 mm wide. or wires 0.135 mm diameter. all responses look to fall of around 15Khz

even the smga (the one with wires) rolled of at 15khz. i am not sure if it really suppose to reach 20Khz as far as i remember it should

lcsaszar 30th April 2017 06:33 PM

I read in some textbook that HF response is inversely proportional with the diaphragm thickness, and no other parameters have any effect. 6 um gives about 15 kHz - not quite sure, need to check. This is for electrostatic radiators.

WrineX 30th April 2017 08:30 PM

1 Attachment(s)
The weight of the conductor should have some influence to i guess. Bolsertst had some diagram somewhere with 3 6 12 micron and the rolloff. hope i can find it somewhere :) also im not sure if the same principals for esl aplly since a magneplanar works some what different


here i did a small test with weight


(RED) 10 micron aluminium foil (2.5mm wide)on 6 micron mylar measured @ menbrame side
(BLUE) 40 micron tape (3mm wide) on 3 micron Mylar. measured @ menbrame side
(GREEN) a laminate of 12 micron mylar with 9 micron aluminium etched (2.5 mm traces)

. they all come really close to each other to be honest :(

anji12305 30th April 2017 08:30 PM

Would a denser "weave" of more conductors help? For older listeners (like myself) this taper is beyond audibility.

Does midrange response coverage of human voices, cellos, saxophones, etc. sound correct?

Would one of these mate well with your excellent Rubanoide?

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WrineX 30th April 2017 08:38 PM

They sound ok to me, i doubt if i can hear beyond 15 kHz, maybe if i try hard with only a sine. but then still it wont do much in music for me. its just that i want to cover the whole spectrum :( it is more common to leave something away down low then in the highs, prob something to do with WAF factor and such ;) or neighbors.

Denser weave, yeah i also think it might have something to do with the ratio of driven area vs undriven area. oen of the bass panels drop at 8 Khz while using same foil on the same mylar. only diference is the magnets are wider so therefore less traces on the foil compared to the tweeter/midrange....... hmmm that might be it. oh god do i need to cut my magnets even smaller :( well i at least try :) just going to cut them with a 3 mm mill instead of the 1mm mill :) the diference in size will be around 1 mm for each magnet.

i should be able to measure something then if it maters at all.

anji12305 30th April 2017 08:45 PM

I'm offering a SWAG here (Scientific Wild *** Guess) that you have sufficient magnetic flux in the gap between rows of magnets, already.

Either more "turns" of wire or lighter traces (less massive foil) would increase the motive force/mass ratio.

Magneplanar in their earliest versions (which I have repaired) used fine gauge wire that was prone to corrosion failure.

What is the finest gauge foil you may procure, at reasonable cost?

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WrineX 30th April 2017 09:01 PM

1 Attachment(s)
Heres a picture of 2 bass panels


1. RED is a bass panels with wires 8.5mm wide magnets and a gap of 1 mm
2. GREEN is a bass panel with aluminium foil 5 mm wide, 8.5mm wide magnets and a gap of 2 mm


so center to center

1 is 9.5 conductor to conductor
2 is 10.5 conductor to conductor , but the conductor is 4.5 mm wider.

the same 5 mm wide conductor on a panel with smaller magnet strips goes higher more in the range of 10khz


One more thing is the highs dont roll off but are a comb filter. so something happens in the foil is my guess. putting traces closer together makes the comb begin higher. at least this is what i see. i might nbeed to try some different material? or damp the **** of the mylar in between traces.

WrineX 30th April 2017 09:04 PM

yeah i did one panel with the wires magnepan uses although be it even thinner al wire. it reached as well 15Khz +- in the meaurement above i used 10micron thin al foil with no benefit. even changing that out for 40micron did not change much.

im a bit clueless.


i

anji12305 30th April 2017 09:11 PM

You know more than any 10 of us.

If you've already used fine wire, I suspect the membrane acts as a mass dampener.

Perhaps a magnetic bar could be applied as a "capo" to separate the HF section from larger excursions?

https://en.m.wikipedia.org/wiki/Capo

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irribeo 30th April 2017 09:28 PM

You only need to show 20kHz, no need to actuallly reach 20kHz, sorry, don't want to offend people :) Do a measurement that shows 20kHz unattenuated somehow :D


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