LS35A Upside Down

LS35A Upside Down

Postby cia » Tue Oct 17, 2006 3:21 pm

Examples of off-centre B110 drive units are not uncommon and may possibly be "cured" by running the speaker upside down or turning the B110 on the baffle.

Has anybody done the above? What was the sonic effect? How long is the "curing" period? Thanks in advance for the info.
cia
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Postby marty_e » Tue Oct 17, 2006 3:52 pm

Hi CIA, I recall the late Mang Lino (Dima) telling me that off center speaker drivers are often caused by the weight of the magnet pulling down on the driver basket over time. Inverting the speaker or its position within the baffle this may cause the sag to correct and re-align itself, it at all. It takes a number of years for the magnet to pull down on the driver. It would probably take the same length of time for the basket to re-align itself if it were inverted. Not sure you'd like to be listening in this manner for a number of years...

Speakers that have already sagged over time is characterized by the woofer incursion/excursion impeded by edges of the driver basket. May sayad, as he would say. If you were to gently push the driver in and out, ala box-test, you'll feel the driver kind of grating over the edge in one side - usually the bottom. I'm not sure how playing the speaker in inverted position would sound, never tried.
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Postby handyboy » Tue Oct 17, 2006 4:02 pm

someone explained to me that technique. I think you know who told me that. maybe you can get in touch with him for more explanation. especially, yours is he white belly which is very old.
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Postby cia » Tue Oct 17, 2006 4:31 pm

Hi Marty,
I tried the LS35A upside down (woofer on top) during the weekend. It seems to me that the sound became a little smoother and slightly more bass. Maybe this is because of the relative change of woofer position to my ear level. Overall, sound was not bad and the speakers did not really look upside down unless you look at the badge.
Maybe you and MVA can try this.
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Postby Superman » Tue Oct 17, 2006 4:35 pm

a resort owner here in Davao (Samal Island) has set-up his LS upside down...at first i found it weird...it's set-up in their resort bar...but with CIA's comments. it's worth listening the 2nd time around...
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Postby KD » Tue Oct 17, 2006 5:07 pm

Yes, I have done this technique. If your LS units are old (mine are 15 ohm white belly Spendors), you may begin to notice garalgal in the B110s at fairly high volume. You can verify the sayad by gently pushing in the B110 cone and the friction will be felt. I had my B110 cones rotated 180 degrees and both the sayad and garalgal disappeared.
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Postby odaey » Wed Oct 18, 2006 9:30 am

Hi Cia,

I don't mean to brag :oops: but as i've mentioned to you you before i have more than one 15 ohmer the oldest of which is a pre white belly rogers which i suspected of having an off center drive unit. It actually produces no distortion when playing and surprisingly enough overloads far more than my 11 ohmers (my best sounding Ls according to a friend) but on inspecting the cone on pressing gently, i thought i felt a gritting sound. I opened up the unit and saw some corrosion setting in on the metal parts cleaned them up, placed some dessicant inside the box played them one week after and then checked for some grittiness on the cones and they were gone.
My assumption was because of the high moisture content of the air from where i live this was responsible for corosion setting in and producing that mild grit on the cones. I now place some dessicants inside all my Ls on a preventive measure (small packs of dessicant are available at ythe nearby ace hardware). Its a common fear among owners of older Ls units when the day comes and the cone sags and become off center but then again when not in use....I STACK THEM UPSIDE DOWN.... seems to work for me so far and no sagging cones yet. But i have'nt tried listening to the Ls upside down. :wink:
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Postby cia » Wed Oct 18, 2006 10:39 am

Thanks guys for your comments. Being that my LS is an old 15 ohmer, I may try to do what KD did and that is to rotate the woofer 180 degrees and redo the box test. Odaey, I dont have much problem with moisture in my neck of the woods. OT....Gamby told me he met you at Rivo's shop.
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Postby odaey » Wed Oct 18, 2006 3:03 pm

cia wrote:Thanks guys for your comments. Being that my LS is an old 15 ohmer, I may try to do what KD did and that is to rotate the woofer 180 degrees and redo the box test. Odaey, I dont have much problem with moisture in my neck of the woods. OT....Gamby told me he met you at Rivo's shop.



Not so sure but you may have to need longer wires from x-over to drive units since the terminals will now be located on the opposite end if you rotate the b110.
Yes, gamby, mike and i met last sat. at hypertriode's. We were actually discussing the same thing.
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Postby ichabod » Fri Oct 20, 2006 10:06 am

Maybe my LS is relatively newer to have this kind of problem. But this much I can tell. I had a full range driver that's can cause this similar problem if one is not careful or is not aware how to place them. A little rotation of the driver simply corrects the distortion. Which makes the observation above valid as it is workable.
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