Hi I'm new to this group.
I have been pondering buying the new 604's from GPA and build 620 cabinets. I have been listening to Lowthers in Mau IV's for the last 10 years (how time fly's). But would like to get slightly more lower mid/upper bass for the next ten .

I have never had the opportunity to hear Model 17's or 19's for that matter. I have heard Klipsch corner horns and was impressed at the time but neither K-horns nor Altec's are abundant in northern Europe.
The views and reviews I have read indicate that I could learn to like the Altec mod 17's and therefore they for me are worth the gamble of a relatively simple DIY approach with GPA drivers and home made cabinets.

I have however recently seen a pair of model 19's advertised for sale (approx 800km's away), but they are not standard. I.e. the 416's has been exchanged with 515-8's (don't know which one) and the compression driver membranes have also been exchanged (awaiting more info) although compression driver magnets are still alnico, cabinets seem to be in great shape (oiled oak).
I could probably bring the comp drivers back to spec. but buying 2x416 as well and exchanging the 515-8's would make this too costly a project. Can the 515 be made to work well in the mod 19's bass cabinets and are there known/tested mods for the standard mod 19 xover for the different 515-8's.
Best regards
Kjartan