My first Aristo head had the D2HI bulb (HI for high intensity). It was a clean, slightly cool light, mostly white, and could not be used with contrast filters without the yellow40 fillter, which would slow it down, and, as Whitey says ranged to the contrasty side.
I now have a new(er) V54 lamp with the "distinct teal glow" Bill mentions. This lamp was designed for VC filter printing, and I find that, after 10 years, the gradation change moving up the contrast levels is not linear, exposures not consistent between contrast grades (as promised by Ilford filter info - but not their fault, the filters are designed, I believe, for incandescent light sources), and larger print exposures can be long.
BUT - I have never achieved the quality of print I can make today with Ilford WT MG fiber, using split filtering with this head. I also bought the head that has a 6" filter drawer above the neg, and purchased 2 filter "holder" frames, so I just open the door and slide in the frame when changing filters. The low end filter is extremely flat, the high one extremely contrasty, so splitting the time is a great way to finesse contrast and range. I can also burn in selectively with different grades, resulting in shadow contrast that I don't think you can get with graded paper.
I think it is not so much about the head unit, but the bulb itself, which I assumed is marked somewhat. If you contact Louise (contact info above) she can help - they may be remanufacturing the basic V54 lamp for your head. The history of the company is long and complicated, but appeals from the APUG community have resulted in some of the original line being made available.
Bill - if your lamp is destictly blue green in color, then I think you have the V54, newer, not older. A simple way to test viablilty with filters is to just print on VC paper with no filter. If it is the old lamp, it will be very contrasty. If you get something closer to normal, likely you have the V54. Somewhere on this forum you can find reference to a simple method of blue and yellow (or green) 2-filter method - using only those two colors to make different grades - a cheap way to start.
Last edited by George Collier; 07-12-2013 at 01:03 PM. Click to view previous post history.