I am now working on upgrading the SC-VIs crossovers with Duelund components. I will have two new external crossovers and keep the original crossovers to compare.
Sorry for delayed response as I don't come on here often. If there is an easy way to find this out without putting the speaker on its side I will help you. But I think I would physically have to to it on its side.
I see that you use your SC-VI with the bases. I don't use mine with the bases and have lost the two pairs of large threads that hold together the speakers and the bases. Would you do me a BIG favor and let me know what is the diameter of the thread in the speaker side?
I am now having someone build two external crossovers for the SC-VI with better components than the stock Solen. It will be done in several phases, and I will keep the original crossovers for comparison. I will let know know how they sound.