LED desklamp for Quartz

[fireball40k]

Has anyone tried an LED desklamp with the Quartz console? Just wondering if a lamp such as the SLED 1 ULTRA XLR3 lamp from Adam Hall would be dimmable on the desk (the pin out of the 3pin XLR looks to be the same).

[yyy898]

well, when i bought my quartz our supplier didnt have the original avo desk lights in stock, so he gave me a led one.
Turnt out it didn't work and he had to send me the original one.

I am sure some will work but deffinatly not all of them, and i think most will not be dimmable

Could be that the output is AC and not DC and then the leds won't work, not sure though

[icke_siegen]

Unfortunately it is a question of polarity: the outlet on a Quartz has a different pinout than e.g. the Tiger Touch II. Clearly: a standard Litlite LED works (dimmable) out of the box with a Tiger Touch II, but needs to be resoldered for a Quartz.

I always wanted to make a little overview for all the console types but haven't managed yet (and havent got one from an humble British company who should know this )

[icke_siegen]

To be fair, for many years the 'original Avo desklamps' were incandescent ones, hence polarity wasn't an issue, and this was probably the reason why none stumbled upon this. In fact when I reported this many years ago the reply was - expectedly: "we cannot reproduce the issue". A good while later I found out that London was still on Tungsten while we shipped LED desklights with the consoles

[fireball40k]

I have a feeling it's going to be more than just the polarity of the connections. LEDs are most effectively dimmed using Pulse Width Modulation, whereas incandescent lamps (like the one that the official Avo gooseneck uses) can be dimmed by altering the voltage/current feed.

[icke_siegen]

In fact the desklamp outlet carries some type of PWM'ed voltage, which does a good job in dimming both, LED as well as incandescent. However, even a PWN'ed signal has a polarity - and obviously this must be the correct one for LED.

I'll talk to the guy from our workshop tommorrow, and will post what he resolders.

[icke_siegen]

I have to revise myself (partly).

Today I tested and measured the desklamp outlet on an old Pearl Expert, an old Tiger Touch, a new Quartz and a new Tiger Touch II.

The polarity is always as announced by Avo: Pin 1 is the negative end, Pin 2 is the positive end of the output resp. the dimmed positive voltage. (and pin 3 is linked to the chassis). That's exactly in-line with the manual, section 2.2.7:

The lamps are 12 volt DC, wired from pins 1 (negative) and 2 (positive) of the XLR

Nowadays Littlites have pin 1 connected to chassis, pins 2 and 3 go to the LED, polarity doesn't matter, see http://www.littlite.com/contentfiledata/download/42.

The little difference is with the dimmer in the Avo console: in a Pearl Expert, it seems that the negative side of the outlet is being dimmed. That's why a standard littlite (LED between 2 and 3) cannot be dimmed but is always full-on (effectively the LED sits between chassis/ground and +12v). In order to make the LED dimmable, you need to rewire the Littlite.

The old Tiger Touch doesn't allow for dimming anyway. The LED sits between chassis (which is connected to 0v) and +12v - usually a standard littlite works.

Tiger Touch II and Quartz: again, the standard littlite LED sits (from the console's point of view) between +0...12v (dimmed) and chassis (connected to 0v). Usually it works.

Since it is not standard behaviour to use the internal ground connection as conductor, of course it is recommended to rewire your littlite: remove the bridge between pin 1 and chassis, and swop the LED wire from pin 3 to pin 1

Arena and Sapphire Touch yet need to be checked but I am sure it will be something along the same lines.

[fireball40k]

That's a very complete answer to the question! Thank you for your efforts.