This is a reprint of an original Review from 1985. The SDA-SRS speaker from Polk, a RARE find and one of the best speakers EVER built! This is the complete review from Stereo Review in 1985. It is a journey into the magic of this speaker and has much information that you will love if you own these gems. It also explains the SDA concept and how it works. Satisfaction guaranteed! A piece of Audio History! This review has a full test of the product, full specs, and commentary. I have many more Polk Ads and Reviews on my eCRATER Store. THANKS! -Each Page is 8.5" by 11"Please check out my new Vintage Audio Web Site, www.VintageAudioArchive.com-Shipping is $3 in the USA and $6 ANYWHERE else, I ship WORLDWIDE! Each additional item is only $1 more to ship!-As always, your satisfaction is GUARANTEED at Electronics Archives! If you are unhappy with any purchase, email and I will get you a resolution or a refund!-Email me with any questions, I put 10-20 new Ads and Brochures on my site EVERY DAY! THANK YOU!Powered by eCRATER . List your items fast and easy and manage your active items.