@au_lait, it is likely that you are going to have to live with a roll off at 40 Hz with these speakers. However, it is likely that they are capable of nice tight articulate bass. The printed circuit board seriously compromises performance. If you are able to build a completely new cross over, as I did, you can eliminate the switches that enable bi amping and provide tweeter attenuation. Those switches seriously compromise performance. They are cheap and are now 40 years old. Mine completely disintegrated when I tried to desolder them. I also eliminated the tweeter protection, which made an easily audible improvement. If you don’t drive them too hard, you can probably get away with this. You will probably also get some improvement in low frequency quality by replacing the internal wiring. I used Duelund tinned copper for this.
One of the things I really noticed after my crossover work is the midrange beauty. Very smooth and refined, as compared to my other speakers, both of which use a 7 inch mid-range.
I would encourage anyone who likes the 1290’s and has spent the money to have Richard So recondition the drivers consider a rebuild or redesign of the crossovers. If you are handy with this sort of thing, a complete crossover redesign, like I did will afford a much improved speaker. However, for those who are less ambitious, simply replacing the stock resistors and caps will make a big difference.