SDA-SRS (original) improvements

Denzel

Helllo everyone...

I have got around to updatng my recently acquired SDA-SRS (original 1988). I have done the usual to my other SDA's... RDO tweet upgrade, posts, xovers, dynamat... but the SRS seems a different beast a bit. For one, what are the donwsides of the SRS vs. the 1.2 or 1.2TL? Seems like most of the gurus want the 1.2 vs the SRS... was the original SRS taboo or a terrible model (now)? I couldn't pass these up...pretty much were delivered to a retirees' home in 1988 and then used to play NPR for 25+ years.. look perfect cosmetically and sound decent...What improvements should I make to these particular SRS?

Thanks as always for the info...

Mr. Bubbles

From my experience with my SRS's. I list what I can recommend from my own experiences.

-crossover capacitor and resistor upgrades
-completely resealing the cabinets (not just the driver gaskets)
-driver gaskets
-SDA inductors
-dynamat all driver baskets
-epoxy all driver magnets (safety reasons only)
-replace interconnect with good binding posts and quality speaker cable to match your main cables.
-check and resolder any necessary (ALL) internal wiring connections or replace all internal wiring/ connectors.
-Hurricane nuts (larrys rings should be slightly better)

I have no experience yet with the RDO's or other internal damping material such as Black Hole but there are a lot of good reviews on its proper use.

I find the sound of the 1.2TL's to be slightly more detailed across the majority of the frequency spectrum. Some of this is due to the tweeter difference, some possibly due to the different mids, and some due to cabinet improvements. The SRS is no slouch by any means. Have fun and enjoy. I also refinished the wood on mine and replaced the grill cloth with a more transparent cloth but could hear no difference in the response with either cloth.

Denzel

Sorry I did not reply sooner... thanks for the info as always. Looks like this will be a good project... any substitution for the rings? (as I think I cant get Larry rings anymore new). I am ready to get them updated and hear the results.

Thanks

Mr. Bubbles

Denzel wrote: »

Sorry I did not reply sooner... thanks for the info as always. Looks like this will be a good project... any substitution for the rings? (as I think I cant get Larry rings anymore new). I am ready to get them updated and hear the results.

Thanks

Hurricane nuts work great. They are available at Parts Express.

Schurkey

The biggest single "problem" with the original SDAs is the inability to use non-common-ground amplifiers. They aren't compatible with the AI-1-style isolation transformers.

Beyond that, the usual host of upgrades will make them a formidable speaker system again.

Shacky

When using hurricane nuts, do you put them on from front or rear of baffle?

Schurkey

Shacky wrote: »

When using hurricane nuts, do you put them on from front or rear of baffle?

I almost addressed that in another thread.
http://www.polkaudio.com/forums/showthread.php?132551-The-Excess-material-in-the-rubber-surrounds-on-the-MW-6503-driver
Figured I'd be laughed at, and deleted my response.

They have to go on from the rear, so that the nut on one side, and the driver on the other side squeeze the "wood" of the cabinet.

I have absolutely no idea why individual threaded inserts would be any less effective than a complete "ring" encircling several threaded inserts. I'd expect the clamp load to be equivalent, and the installation headaches--trimming the metal rings, where needed--much less.

DarqueKnight

Denzel wrote: »

What improvements should I make to these particular SRS?

Mr. Bubbles provided some great suggestions. Here are some illustrated threads of modifications I performed on my SRS's:

Improvements-to-the-SDA-SRS

Further-Improvements-to-the-SDA-SRS-Custom-PCB-and-SDA-Inductor

SDA-Driver-Seals-Original-Foam-vs.-Mortite-vs.-Armaflex-Foam

Mr. Bubbles

Schurkey wrote: »

I have absolutely no idea why individual threaded inserts would be any less effective than a complete "ring" encircling several threaded inserts. I'd expect the clamp load to be equivalent, and the installation headaches--trimming the metal rings, where needed--much less.

I have never used the rings and can not definitively say whether larry's rings are better or not. At the time I was working on my SRS's funds did not allow me to get them. However, if that had not been the case, I would have preferred to try them instead of the hurricane nuts due to the following; If the material the ring is made from is heavy enough, the ring itself will more evenly bear the load of the clamping force around the driver opening. Where as the nuts create a more concentrated area of force. Think of it like spikes as compared to the flat bottom of a speaker cabinet. The same total force is created in each case, but the contact force varies greatly.