Subwoofer and tweeter for Quads

I was wondering if anyone ever tried high-quality subwoofers and tweeters with old Quads (ESL 57 or 63) for low and high frequencies, and with what results.
Hello Ggavetti,

I have owned several pairs of Quads (57's and 63's), and have some unorthodox ideas about how to combine a tweeter and a subwoofer with them.

On the tweeter, in my opinion the problem with the Quads is beaming. They have decent high frequencies on axis, but there is a shortage of high frequency energy in the reverberant field because it isn't getting the benefit of much off-axis energy. My solution was to take a dome tweeter and place it face-up on the floor about a foot or more behind the speaker. This way it did not contribute to the first-arrival sound, but rather to the reverberant energy which is where there was a shortage of high frequency energy. I just used an inexpensive Vifa one-inch dome.

In the bass region, I did a lot of experimenting trying to find a practical woofer system that worked well with speakers like Quads and Maggies. I won't bore you with the odyssey, but ended up going with four small subwoofers spread around the room. This approach gives in-room bass smoothness comparable to a pair of dipoles, but with better impact than dipoles. Credit to Earl Geddes for the idea.

Have used the Hartley/Quad/Decca combo,but preferred the Magnepan bass panel (3B).Wish I could have heard them with a set of Fountec ribbons.
Had a pair of Quad ESL 57's. Tried REL Stadium III, Martin Logan Dynamo, Snell and M& K subs. No question the REL was the best match. Fast and easily adjustable so as not to overlap into the Quad range. I agree with Duke on the multiple sub technique. I currently use a pair of Von Schwiekert vs/1. They are great. If I were to use 4 these would be my choice. Although I never got to use them with my Quads. Have not tried that tweter set up but I like the "sound" of it.