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Old 17th January 2006, 06:35 PM   #1
taotao is offline taotao  Germany
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Default renewing sequel2 panels

Hi audiophiles,

I need some clarifications to the result from my restauration of ML Sequel panels.
The original membranes didn't builld up enough charge (I guess), sound was dull and boomy.
I think ML coated their older models with graphite and it seems this stuff looses the abillity to be charged in a (long) period of time (mine are the first sequel 2 models ).
So I got 6my of mylar and EC Coating and repaired the panels (really not so easy to get wrinkle free :-() and still not perfect, I will do again.
But it's allready noteable how the sound balance got much better. Highs are there with shiny sparkling (cymbals, hihats etc.) And also mids have a nice resolution.

Only two things I'm not clear about: One speaker is louder. The foil of the one with less efficiency wasn't masked before coating and I applied the liquid everywhere.
This was not so clever, because discharging occurs somewhere at the border of the panel (this my theory) Could this be the reason for the reduced efficiency?

Second, both speakers sometimes produce a high frequency whistling sound. It beeps for some seconds and then is gone. What could be the reason for this? Could it be the tension of the mylar (not enough tensioning)??

I hope somebody can tell me

Bye
Olaf
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Old 18th January 2006, 09:01 AM   #2
Calvin is online now Calvin  Germany
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Hi Olaf

(sorry anyone else for answering in german)
die Beschichtung solltest Du wenn möglich schon mittels Maske aufbringen, da alle Punkte, wo eine direkte Verbindung zwischen Membran und Stator besteht -also auch unter den horizontalen Abstandhaltern- anfällig sind für Leckagen und Überschläge. Bei den Beschichtungen der älteren MLs kann man deutlich erkennen, daß die Beschichtung innerhalb der einzelnen Segmente nie die horizontalen Spacer berührt. Zur Kontaktierung der Beschichtung allerdings musst Du bis auf die seitlichen Abstandhalter beschichten. Der wenige Millimeter breite Kontaktstreifen sollte halbwegs mittig auf den Abstandhaltern positioniert sein und die Beschichtung nicht bis zum Aussenrand der Folie aufgetragen werden. Es ist auch vorteilhaft, den Kontaktstreifen in U-Form, bzw. als zwei links-rechts auf der Membran befindliche Streifen auszuführen.

Wichtig bei den MLs ist die mechanische Spannung, da die daraus folgende Lage der Grundresonanz in die Weichenabstimmung reinspielt!

beeping: Es ist nicht einfach Ferndiagnosen zu stellen, wenn die Membranspannung allerdings zu niedrig ist gibt es zwei mögliche Phänomene.
- Die Membran wird an einen der Statoren gezogen und bleibt dort kleben (bei kunststoffbeschichteten Satoren fast immer der Fall). Dabei wird dann ein leises andauerndes Knistern bis Prasseln hörbar, je nach Höhe der Polarisationsspannung. Nach Abschalten der Polarisation dauert es in der Regel einige Minuten bis sich die Folie unter Popp-Geräuschen vollständig wieder löst
- Die Membran wird an den Stator gezogen, klatscht deutlich hörbar dagegen, es gibt eine Entladung, die Membran löst sich und klatscht bei der nächsten Signalwelle wieder gegen den Stator. Ein lautes knatterndes Geräusch wird so erzeugt.

Ein Pfeifen deutet dagegen eher auf einen elektrischen Effekt hin und weniger auf einen mechanischen.

jauu
Calvin
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Old 18th January 2006, 06:57 PM   #3
taotao is offline taotao  Germany
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Hallo Calvin, vielen Dank.
Das mit der verschobenen Reso muß ich vielleicht auch noch ausgleichen.
For all:
I understand;
There are at least two factores, I've got to consider. The thinner mylar and the lower tensioning lead to a different resonance frequency.
In this case I guess the thinner foil counts less than the tensioning.
My expectations would be, that the frequency should be lower than the original Panels (maybe 60 Hz vs. 95 Hz). Is this right?

This won't influence the response at the 6db baffle step slope so much, but more the range at crossover frequency. As a result I expect a bump in lower response region of the panel.
I think redesign of the crossover is a must in this case . Maybe the bump is not so worse and I can live with it. (I'm not so shure if this is audible)
I realy should get a mike to messure acustical output.

Next foils will be masked and better tensioned :-))

bye

P.S. What's the thickness of the original ML SL2 membranes? Can somebody tell me? I read somewhere it's 12 my.
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Old 25th January 2006, 04:20 PM   #4
Calvin is online now Calvin  Germany
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Hi,

the MLs have fs of around 250Hz using 12µm film.
Thinner films don´t allow for similar high Fs. with 6µm 200Hz should be the max.
All other conclusions are correct

jauu
CAlvin
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Old 25th February 2007, 06:00 AM   #5
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Hi,

I am trying to fix a sequel2 panels. Can you give some advice how to disassemble diaphrame from stator without damaging the diaphrame?

Soonmo
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Old 25th February 2007, 10:54 AM   #6
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Hello

Does someone know the exact thickness of the spacers as they are used in the sequel2???

By, MartinJan
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Old 25th February 2007, 05:46 PM   #7
Calvin is online now Calvin  Germany
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Hi,

@mims:

You won´t be able to disassemble the stators without destroying the membrane. Since You can´t use it again anyway, You can immedialtly install a new one!

@MJ
ML used the VHB-Tapes of 3M. As I remembrer they took 1.5/1.55mm or 1.0/1,1mm. For crossover-fregs as high as in the MLs -and the corresponding high mechanical tension- 1.0/1.1mm is sufficient for all instances.
I use 1.0/1.1 in my stators (which are of Sequel size)

jauu
Calvin
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Old 25th February 2007, 07:33 PM   #8
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Quote:
Originally posted by Calvin
Hi,


@MJ
ML used the VHB-Tapes of 3M. As I remembrer they took 1.5/1.55mm or 1.0/1,1mm. For crossover-fregs as high as in the MLs -and the corresponding high mechanical tension- 1.0/1.1mm is sufficient for all instances.
I use 1.0/1.1 in my stators (which are of Sequel size)

jauu
Calvin

Hi Calvin,

Won't the capacitance increase too much if you use as small as 1,0 mm as a spacer?

In my curved wire esl I used around 1,0 mm (both sides) spacing and in my opnion the Mylar in the middle parts had somewhat less spacing because it is quite impossible to maintain the perfect curvature of the mylar. However because of the high mechanical tension, the deviation was acceptable. Since you mention 1,5 mm as spacing I will use that instead of the 1,0 mm.
The spacers will be put closer together to allow thinner films of Mylar. The sequel2 has cells as high as 12 cm but I will try around 7 cm and 5 alternately to distribute resonance.

BTW you're right about output. With 1,0 mm spacing even a small unit with a 1:50 step-up makes a lot of sound

Yeah, MartinJan
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Old 26th February 2007, 06:39 AM   #9
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Calvin,

Thanks a lot for the reply. How can I install a new membrane? I know there's lot of information regading ELS DIY and I have to search but your direction will be really helpful.

I heard that I can use "tape residue remover" to soften the glue between stators. Where do I get the 6 mm mylar and EC coating? How do I install membrane? I do I make the connections between membrane and wire to the hv?

Thank you in advance.

soonmo
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Old 26th February 2007, 07:24 AM   #10
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Quote:
Originally posted by mimsguru
Calvin,

Where do I get the 6 mm mylar and EC coating? How do I install membrane? Thank you in advance.

soonmo

Hi,

I am the producer/supplier of the EC-coating. I've got genuine (custom made) mylar as well.

The EC-coating offers the best chemical and physical properties currently available. Because of its chemical composition it has to be used within 5 to 6 months (exact date is on the bottle).

For more information: please contact me, mj-dijkstra@zonnet.nl
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