Dual Dlumotechs?

[TonySmith]

I've been running a B+M sidewall dynamo with front & rear lights for a couple of years and would now like to upgrade to a SON before next winter. In the SJSC online shop the E6-Z headlamp is described as "the ONLY" secondary headlamp, yet Peter White's site shows an installation using dual Lumotech Rounds and I've seen a secondary version of this lamp on B+M's website. The wiring diagrams I've seen indicate that a secondary headlamp is simply wired in series, with a switch to bypass it for single lamp operation so surely any headlamp could be used for the sake of wiring up a switch?
 On a related note I'm interested in the new Dlumotech LED headlamp, mainly for reliability. Would it be possible to run a pair of these or will the fancy electronics cause problems? OK so a blown bulb in a secondary lamp doesn't really matter but it'd be nice to have a matched pair!
 Can anyone advise?

[Dave Whittle Thorn Workshop]

Schmidt no longer make the Bush and Muller secondary lights, E6 only now.  We have tried wiring in another and an inline switch but it wont work, Schmidt know why but they wont tell us! The secondary isn't that much more than a primary so we are prepared to accept this.  Havn't seen a Dlumotech light will have to investigate, so no comments on that i'm afraid.

Dave Whittle SJSC

[PH]

The Schmidt lights are the only ones I know of that are designed as a primary and secondary, they also contain some clever electronics that enable you to use the second light at 9mph, rather than the 12mph needed if you wire two primary lights together.
I don’t understand what problems Danger Mouse has had in getting two B&M lights to work, I know of several Audax riders who’ve done this.  Schmidt don’t make any secret of how to do it, there’s a wiring diagram on their website
http://www.nabendynamo.de/12vinfo.htm
My experience with LEDs is that they make fantastic “be seen” lights and offer a good spread of short range illumination, but even the most powerful I’ve seen don’t penetrate as far as a filament bulb.  I haven’t seen the Dlumotech in action so maybe this could be the exception.
I’ve been commuting on a Raven with Schmidt hub and twin lights throughout the winter (14 miles each way and always in the dark) I’ve been very impressed.  If I was buying now I’d consider a Dlumotech as the primary and a Schmidt as the secondary, the idea of an everlasting “bulb” is appealing,  though I wouldn’t want to sacrifice the  ability to use the secondary at lower speeds ( I dont know how or if that combination works). Part of my commute is canal path, the slowest part, but where I most need the lights!

[TonySmith]

I understand that with a B+M you don't get the fancy electronics for low speed boost but am surprised it doesn't work at all. I know you have to isolate the earth of one lamp (or use the earths as a feature and wire the secondary backwards)and can see problems with using lamps with standlights/auto on etc. but don't understand why this shouldn't work for a simple lamp with no electronics.
 Since starting this I'm actually coming round to the idea of using an E6 secondary as it apparently has a more focused beam - exactly what I want for higher speeds to compliment the wider beam of the main light. Of course, on that basis the idea of using the Dlumotech is more appealing with it's more diffused beam and usable output at very low speed. Only review I've read was in VV but that was just a single headlamp with B+M S6. Come on Danger Mouse, test one with an E6 for us!
 Also, how would I mount the lamps? I currently have a Thorn fork crown bracket and can see how two lamps could be mounted using a threaded bar and a few nuts or perhaps a long bolt and the dynamo spacer thingy SJSC make (I don't mind the secondary being offset). I remember seeing twin lamps on a Raven in the showroom but that was a long time ago and I didn't pay attention.