Durst M601 - Bulb wattage?

I recently bought a Durst M601 in mint condition. It came with a 150W bulb (+ identical new spare). Any idea if this might have been the original configuration / recommended wattage? The enlarger head gets very ( ! ) hot after a short while and even at f.16 I cant seem to push exposure times to more than max 10-11 sec which give me very little time to work on my print.. I haven't been in a darkroom in 20 yrs so quite rusty : ) Have I missed something or is the bulb wattage way to much? Also appreciate any info on use "modern bulbs" like LED etc. in the M601. Thanks!

Welcome!

Maximum 150W

Thus nonone would stop you from using a opalescant bulb of lesser power.

Even though 150 is the max, a 75 might work better, both for heat and your exposure times.
LED bulbs can produce a lot of heat due to the driver electronics and the heat sink that keeps the LED from burning up, they probably wouldn't be very happy in a tightly enclosed lamp housing.

I never used anything but a 75 watt lamp in my M601, it's a pretty efficient machine and has only 6x6 for maximum film size.

bdial said:

LED bulbs can produce a lot of heat due to the driver electronics and the heat sink that keeps the LED from burning up, they probably wouldn't be very happy in a tightly enclosed lamp housing.

Click to expand...

LED at same light output have much lesser heat loss than incandescant lamps.
I thus guess your idea is their heat diffuser are so tiny, compared to the bulb surface, that they would need some airstream instead.