Also, please note those panels won’t really fit right in the A-1s, cosmetically. If you are just using backplate with a seperate frame you build, you will be good to go.
Actually, you would need to construct wooden boxes to house the back plates, similar to the ones pictured above and I assume are an integral part of your A-1’s.The boxes then bolt to the panels. The panels should have threaded nuts already embedded inside. You might check with SL to verify this.
The 545 panels will work with your back plates. They would bolt directly to the plates, no frame needed. The frame is purely decorative and adds nothing sonically. Essentially, you will be creating the Majestic configuration. You can add wood trim on the sides. Study the photos on the SL website and the attached photo here of my no longer owned Majestic 945’s.
If anyone is interested in a practically new M545 bass focus panels (the latest) without the back plates, let me know. Brand new M545 costs $15,000. I am moving to a bigger room and want to get larger panels. I will give it away for a great price. If you already have back plates, this is an incredible deal.
call me or text me at 301-339-3135 as soon as possible. I am eager to sell.