So I have another thread here talking about my purchase of these new (old) SDA-1C's. Now that I've got them, I figured I'd create a new thread to talk about 'em a bit.
Long story short, they appear to be one of the in-between models that were built during periods when Polk was transitioning models. From a crossover and driver standpoint, you can see the details in the above thread that we've determined that they are definitely SDA 1C's, but they're unusual in that they have a blade/blade SDA interconnect, whereas the 1C's normally have the pin/blade connector. Yet when I pulled them apart the SDA connection is only a single conductor, whereas a blade/blade usually is dual conductor. So I guess Polk had a few spare blade/blade connectors and cables they wanted to get rid of at the time...
So I immediately ordered up the Sonicaps, Mills resistors for a crossover upgrade, and some nice Cardas posts and of course new tweeters. Unfortunately there's no upgrade for these crossovers so I could use the RD0198 tweeter, so RD0194's it is. Don't even start Carl....
If you read my 2B mod thread, I did inductors on those as well. I decided not to do inductors here, though. The 2B's use quick connect posts for the inductors, making the mod easily reversible. Not so easy with these, so I decided to just leave the inductors as is.
Ok, so pics....
Here they are before I started ripping into them, posing for a picture in front of their baby brothers:
I pulled the passive radiator, here's what I saw inside:
(Notice the single conductor going to the SDA interconnect in the above shot...)
Ok, well that's just not going to suffice, time to start upgrading!!!!
I pulled both crossover units, one is mounted to the back of the binding post assembly, one's mounted to the large inductor and attached with a screw that you need to remove from the back with an allen wrench.
Yummy! Spent more on those caps than I did on the speakers! The third binding post assembly is to replace the blade/blade connection so I can use speaker wire for the SDA interconnect. Frank at Signal Cable made me a cool Ultra with one banana and one spade at each end, so I could connect both strands to the single binding post. Now that's an SDA cable!!!
These xo's were a bit trickier to do than my 2B's. Yanking the polyswitch was tough because it runs underneath one of the little inductors on the high-end xo. Need to be real careful prying the inductor loose to get at that polyswitch. Also a few places where one component needed to solder onto the next component, rather than each piece having a dedicated soldering post on the circuit board. Nothing too difficult, just a bit more involved than the 2B's.
So here's the finished product. First the high side:
Three Mills resistors and the 12uf Sonicap (I did not use a bypass) on top of the board as seen above, and a 4.4uf Sonicap mounted below:
It's kind of hard to see in the above pic, but the 4.4uf Sonicap just fit in between the tops of the regular binding posts and the SDA binding post. If that cap had been any bigger, I would have had problems.
Now for the low end. I just think this looks so bad-ass. Three 20uf Sonicaps - over $80 in caps just for one low-end xo! The schematic calls for a 20uf and a 40uf. There's no such thing as a 40uf Sonicap, so I used two 20's (so did the stock xo):
Here's the binding post assembly. Shame to put tape over those gorgeous Cardas posts, but making them red/black makes things soooooo much easier. Jesse, sorry, I used the boots again. I know, I know....
Took two nights to do that work. I put the new tweeters in and fired them up last night. They were making music on the first go, so didn't have any diagnostic work to do (whew!) I've had them burning in for about 18 hours now. I'm not noticing a whole lot of difference in the sound yet, the only thing that's changed is when they first came up there was a bit of static - crackles and pops kind of thing. Same thing happened with my 2B's, it takes a bit of time for the Sonicaps to settle down. The crackles are gone, but they still need more hours before they really start opening up.
So another fun mod project. Next up are the grill cloths, I'm telling you right now I'm going to need a bit of advise with that end of the project!
Looking forward to getting them fully burned in so I can do a bit of 1C vs 2B-TL comparison...
Ok, I got no sleep last night, so I'm heading to bed. Time to get up for work soon enough, gotta earn a buck or two to pay for these Sonicaps!!!!! Nite all....