My 2As Finally Finished...Almost

westmassguy
westmassguy Posts: 6,850
edited March 2014 in Vintage Speakers
I doubt they'll ever be really finished, but they are sweet now. Last year I had built a Hybrid or "Franken-Polk" out some 2A crossovers and my monitor 10s. They came out very nice, full SDA effect, and performed beautifully. I recently picked up a pair of real 2As, that were in good to excellent condition. I tranfered my already rebuilt crossovers and RDO-194s over to the 2As. The bass was better, due to the larger cabinet, and larger PR. When I rebuilt the crossovers last year, I used Sonicaps and Mills for the Hi-Pass, and Daytons for the Low-Pass shunts, except for the huge 130 uf electrolytics, two per crossover. I couldn't afford them at the time, so I installed some fresh NP Electrolytics, to tide me over. Business has been good, so I decided to finally replace those Electrolytics. In addition, I'd also been reading Mathew Polks opinion on inductor upgrades, specifically the inductor connected to the negative terminal on the dimensional woofer and the amps ground. Although he references a later generation than my 2As, the theory should still apply. The problem with 2As is, they're already sitting at 4 ohms to begin with. My Carver can handle 2 ohm loads, so I wasn't worried. MP mentioned/recommended Laminated Steel Core Inductors. The original 2A inductor is 5.6 mh, 18 gauge, with a DCR of about 1.5 ohms. Erse makes a great Laminated Steel Core Inductor, so I chose a 14 gauge with a DCR of around .2 ohms. Instead of the 130 uf caps at $50.00 each, I opt'd for three 90 uf caps per side, which saved me $50.00. I used a break-out board to mount the three 90s, and used some 12 gauge OFC to wire up the Caps point to point. The inductor leads were long enough, so I was able to solder them directly to the crossover board in place of the originals, and mount the new inductor to the back wall.
While I was at it, I replaced the blade/blade connectors with Speakons, and made a new cable using some old 10 gauge OFC speaker cable I had laying around. As a final touch, I spiked them. I found a seller on Long Island that has some real nice quality gold plated copper spikes. They were only $26.00, including shipping, for a set of eight. Got everything buttoned up this afternoon, and I was floored by the difference. The bass which was good, is now exceptional. Not flabby, not boomy, just exceptional. It's like I just added two subwoofers. All the changes I made affect the bass, but my personal feeling is it's the inductor that made all the difference. Like MP said, if you amp can handle it, change the inductor.
Home Theater/2 Channel:
Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer

dhsspeakerservice.com/
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