Scratchy Lowther driver - suggestions requested

HCX · 7th November 2008, 10:06 PM

Hello everybody out there in diy-land.

A couple of years ago I bought a set of Lowther PM6C drivers. I have eventually put them to use, in a two-way open baffle.

The result is interesting, BUT: at a bit of volume and at certain (high-ish) frequencies, there's a screeching/scratching noise from one driver. If I gently push the cone back at the whizzer, I can hear and feel the voice coil scratching against the magnet, like it's misaligned in the air gap. At least that's the impression I get.

Now, how do I repair this? Is it possible to repair this whithout beeing an expert?

Will staring or talking hard at the bad driver make it improve? Or should I try something else? Suggestions are welcome!

HC

Nelson Pass · 7th November 2008, 10:13 PM

Voice coil is possibly off center. If you have some non-magnetic wrenches
you can re-center it, otherwise you might need re-coning.

limono · 8th November 2008, 03:59 AM

it is fairly easy to align lowther driver . Go to Lowther America website
and read "how to". I had a scratchy DX4 and fixed it without any problem.
Just proceed carefully .
Regards, L

dnsey · 8th November 2008, 08:07 AM

Once you've sorted it, remember to rotate the drivers 180 degrees every few months, to compensate for the tendency of the suspension to sag.

Jon Ver Halen · 8th November 2008, 07:36 PM

If you want my repair sheet, send me an e-mail and I will forward it to you. It is not on my website, which is about to get a major revision.

The sagging suspension problem existed when Lowther used natural foam rubber surrounds. These were known to sag over time, and for that reason were phased out a long time ago. New suspension and surrounds do not sag, and do not have to be rotated every 6 months.

HCX · 8th November 2008, 07:47 PM

Thanks for all replies.

I'd like to realign my driver if possible. Access to non-magnetic wrenches is possible. I'll ask my mechanical engineering ph.d. dad if I can use his extensive collection of tools.

I took a look at the Lowther America website, but found no "how to"-section. Please supply link, and I will throw myself upon it and rapidly accumulate alignment knowledge. I hope.

Lowther rules (probably)!

Have a nice weekend,
HC

7th November 2008, 10:06 PM	#1
HCX diyAudio Member Join Date: Apr 2005 Location: Asker, Norway	Scratchy Lowther driver - suggestions requested Hello everybody out there in diy-land. A couple of years ago I bought a set of Lowther PM6C drivers. I have eventually put them to use, in a two-way open baffle. The result is interesting, BUT: at a bit of volume and at certain (high-ish) frequencies, there's a screeching/scratching noise from one driver. If I gently push the cone back at the whizzer, I can hear and feel the voice coil scratching against the magnet, like it's misaligned in the air gap. At least that's the impression I get. Now, how do I repair this? Is it possible to repair this whithout beeing an expert? Will staring or talking hard at the bad driver make it improve? Or should I try something else? Suggestions are welcome! HC

8th November 2008, 07:36 PM	#5
Jon Ver Halen diyAudio Member Join Date: Aug 2004 Location: Chicago area	Scratchy Voice Coil If you want my repair sheet, send me an e-mail and I will forward it to you. It is not on my website, which is about to get a major revision. The sagging suspension problem existed when Lowther used natural foam rubber surrounds. These were known to sag over time, and for that reason were phased out a long time ago. New suspension and surrounds do not sag, and do not have to be rotated every 6 months. __________________ Jon Ver Halen Lowther-America

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7th November 2008, 10:13 PM	#2
Nelson Pass The one and only Join Date: Mar 2001	Voice coil is possibly off center. If you have some non-magnetic wrenches you can re-center it, otherwise you might need re-coning.

8th November 2008, 03:59 AM	#3
limono diyAudio Member Join Date: Mar 2007	it is fairly easy to align lowther driver . Go to Lowther America website and read "how to". I had a scratchy DX4 and fixed it without any problem. Just proceed carefully . Regards, L

8th November 2008, 08:07 AM	#4
dnsey diyAudio Member Join Date: Mar 2004 Location: Shropshire, England	Once you've sorted it, remember to rotate the drivers 180 degrees every few months, to compensate for the tendency of the suspension to sag.

8th November 2008, 07:47 PM	#6
HCX diyAudio Member Join Date: Apr 2005 Location: Asker, Norway	Thanks for all replies. I'd like to realign my driver if possible. Access to non-magnetic wrenches is possible. I'll ask my mechanical engineering ph.d. dad if I can use his extensive collection of tools. I took a look at the Lowther America website, but found no "how to"-section. Please supply link, and I will throw myself upon it and rapidly accumulate alignment knowledge. I hope. Lowther rules (probably)! Have a nice weekend, HC

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