# Difference between single and dual chamber headlights??



## less.than.jeff (Sep 2, 2008)

I'm looking into a headlight upgrade and was wondering what the difference is between dual chamber and single chamber lights? Is either particularly better?


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## pilotlars (Aug 19, 2004)

*Re: Difference between single and dual chamber headlights?? (less.than.jeff)*

single-reflector headlamps use a dual filament headlamp bulb (H4,9004,9007,H13,etc) and when the high beam is activated the low beam automatically turns off as to not over-heat the bulb. i'd venture to guess that nowadays most dual-reflector headlamps have seperate single-filament bulbs for the low and high beam applications. normally the lows remain on when the high beams are activated. this is not always the case, such as with some late 80s and early 90s american cars and trucks. some dual-reflector units, however, are simply a dual-filament hi/low beam with an additional inboard high-beam for additional light. especially with E-code lights, a dedicated low-beam only reflector can produce more light as compared to a dual-filament lamp, which is sort of a compromise. with the exception of the new Hella bi-halogen lamps for the ford focus, GM Astra and the golf 5, all projector headlamps i've seen are LOW beam only. the inboard relfectors would be the high beam units. normally projector lamps are suprerior to reflectors (again, i'm only talking about E-code lamps here, evaluating SAE lamps is a waste of time, as they are horrible no matter what style they are). xenon (HID) systems can be projector or reflector low beams, or a bi-xenon setup where the shield in the projector folds to to provide the high beams. 
so to summarize: dual is (normally) better than single reflector,
projector is better than relfector
xenon trumps all else!


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## less.than.jeff (Sep 2, 2008)

*Re: Difference between single and dual chamber headlights?? (pilotlars)*

Wow man thanks! That really helped me out.


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## pilotlars (Aug 19, 2004)

*Re: Difference between single and dual chamber headlights?? (less.than.jeff)*

NP man, anything I can do to help I'm glad to do. I see you are north of me in WA? Lars


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## pilotlars (Aug 19, 2004)

*Re: Difference between single and dual chamber headlights?? (pilotlars)*

here is an isolux diagram of a parabolic reflector E-Code headlamp:

This is an FF (clear-glass style lamp):

This is a DE (projector style) headlamp:

And here is side by side comparison of xenon/HID vs. halogen headlamps

All pics are from Hella.


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## Maxxymus (Feb 27, 2008)

*Re: Difference between single and dual chamber headlights?? (pilotlars)*

very impressive answer pilotlars....but.... wouldn't a bigger reflector bowl be better then a smaller one(considering that both bulbs have the same light output)?...my 2 cents
oops,i was reading from the airplane...your answer is complete(i didn't pay enough attention,my bad)


_Modified by Maxxymus at 3:01 PM 5-27-2009_


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## pilotlars (Aug 19, 2004)

*Re: Difference between single and dual chamber headlights?? (Maxxymus)*

I would agree that a larger reflector is better than a smaller one. If one looks at the isolux diagrams from Hella, their larger, jumbo 320 and rallye 3000 driving lights have amazing light output, especially the xenon variants. smaller front end are modern, but large reflectors are better!


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