For a project, I am looking for a 175 watt, protected, ED/BD-17 metal halide lamp. Between GE, Philips, and Sylvania, is there any one of the 3 that is better quality (light output/color, life) than the other two? Or, is there another brand that is better than all 3? I have found some off brands on the net I have never heard of and because of that I am not sure about them. I am also having a tough time finding a CMH in this lamp that will run on an M57 ballast...does that exist?

Thanks.

Ceramic are only PulseStart and i think only wattages 20, 35, 70, 100, 150, 250W. May be higher wattages will arrive, but with higher wattages the performance difference between CMH vs QMH is disappearing, but the arctube cost rise very steeply (ceramic is more difficult material then quartz, what cause more problems and lower yield with larger sizes)

Yeah that's what I have been finding out about CMH. That's ok, I have a 100 watt PSMH fixture I could get a CMH bulb for and I think it will be a Philips Mastercolor as I really like the unique looking arctube.. As for the 175 watt protected MH lamp, it looks like it will be a Sylvania lamp, unless someone can suggest a different brand is better.

For CMH i have best experience with Osram (Sylvania in US) "Powerball" (HCI-xxx; spherical bubble-like arctube) - they have much more uniform wall temperature. But if i compare their prices on e-shops here, they are ~20% more expensive then otherwise equivalent Philips CDMxxx...

There are now 400 watt CMHs.

There are now 400 watt CMHs.

It is possible, but they for sure are expensive like hell and the only their advantage would be availability of warmer color tones combined with high efficacy and high CRI - these do not mix well with QMH technology. But for colder tones the QMH yield nearly the same efficacy and CRI for higher wattages as CMH, but at lower lamp cost. It is given by the fact, then higher wattages suffice with longer arc (to keep the arc loading sufficiently high), so lower gas pressures, so wall temperature, what quartz might endure.
The issue with warmer tones is, then these need higher sodium content, while sodium is highly reactive with quartz - so even when halides suppress this effect, still some sodium come to contact with the arcube, so it content has to be limited in QMH. But as the ceramic is inert towards the sodium, there is no such limitation with CMH.