Originally posted by raife:
Modification Ritual for SDA SRS 1.2TL
1. Prior to upgrade, do a few hours of critical listening with well-recorded LP's and CD's. Take very detailed notes with regard to instrument placement in the soundstage, general dimensions of the soundstage, subtle musical details, and the realism of sound as compared to live performances. Make diagrams of the apparent placement of instruments and vocals within the soundstage.
2. Order Crossover Schematic from Polk Customer Service.
3. Study schematic and make a parts list of items to be replaced.
4. Take accurate measurements of crossover circuit board and measurements of stock crossover components (electrolytic capacitors, mylar capacitors, and cermet resistors).
5. Check parts vendors online catalogs for required parts. Pay particular attention to the dimensions of potential replacement parts. You want to make sure everything will fit on the circuit board.
6. Order AudioCap PPMF polypropylene capacitors (1.5uF, 12uF, 27uF values), Cardas silver quad-eutectic solder, and Cardas heavy-duty, telurium copper gold-plated binding posts from SonicCraft of Wichita Falls, TX. Cost: $293. 79. The binding post replacement requires that the holes in the binding post plate be enlarged. I used a drill bit.
7. Order Mill's MRB 1% tolerance wirewound, low inductance resistors (2.7 ohm, 7.5 ohm, 12 ohm, 15 ohm, 22.1 ohm), and 0.22uF PPMF-X metalized polypropylene film capacitors from Michael Percy Audio of Nevada City, CA. Cost: $52.93.
8. Buy two yards of 60" wide thin, silky-black knit fabric from the local Hancock Fabrics store. Stock #46794. Cost $10.44. Use this to replace the thicker stock grille cloth.
9. Go to Home Depot and buy two four-packs of 1-1/8" teflon sliders to cover the metal feet on the bottoms of the speakers. Didn't want to scratch my hardwood floors.
10. Complete all modifications for the right speaker and then do detailed listening tests comparing it to the unmodified left speaker. Listen with and without the interconnect cable in place. Take very detailed notes.
11. Complete modifications for the left speaker. Working carefully, the crossover, grille cloth, and binding post modifications took a little under three hours per speaker. This was not a trivial exercise. Care must be used to mark the positions of the components and component lead insertion points on the circuit board. Because of the larger sizes of the replacement capacitors and resistors, some components had to be mounted on the underside of the circuit board. After soldering, components were secured with plastic locking straps.
12. Do a critical post-mod listening session. Do not refer to previous pre-mod listening notes. Take very detailed notes with regard to instrument placement in the soundstage, general dimensions of the soundstage, subtle musical details, and the realism of sound as compared to live performances. Make diagrams of the apparent placement of instruments and vocals within the soundstage.
13. Mentally compare notes from the pre and post mod listening sessions. Compare the actual listening notes and soundstage diagrams from the pre and post mod listening sessions.
14. Smile from ear to ear.
Total parts cost of modifications was $364.72.
I did not replace the internal wiring because I did not notice a difference when I replaced the internal wiring of my SDA 1B's.
Improvements in sound: Not a night and day difference, after all, they sounded very good to begin with.
A. The biggest improvement was in the solidity and three-dimensionality of the soundstage. Soundstage was wider and deeper, with more of a sense of real musicians being in the room.
B. Bass was tighter and "punchier".
C. More resolution and detail throughout the entire frequency range. The resolution continued to slightly improve over a period of three weeks as the new parts were broken in. Over this period, I was constantly surprised by subtle musical details I had never heard before, particularly with my Jazz LP's.