SDA-1 Upgrade As or find some Cs???

gdb

The more I read on here about the superiority of the C version of SDA-1s over the A version, the more I'm wondering if I should hold off on upgrading my 1As and try to find some 1Cs, I think that in stock/unaltered condition,
the 1As sound great with the exception of the tweeters that I cut the treble on quite a bit. I had hoped to get the chance to hear a members re-done Cs at a festival in September so that I could see how they compared to mine,but it's looking like I won't be able to make the trip now:( Will there be any rigs with SDA-1s around at the Polk get together in Baltimore this year? I live closeby and could definitely get to that one. Any advice on which route to take on the SDA-1s will be appreciated! Thanks gdb

ben62670

Try disconnecting the outer tweeters. The first generation had two woofers as subs, one stereo, and one dimensional. The C's are better, but for a small investment the originals can be done up real nice over stock too.
Ben

treitz3

Wasn't the ohm rating different between the two as well? IIRC, the 1A's were 4 ohm and the 1C's were close to 6.

gdb

Hi Ben, I'm still going to ask you to re-do my XOs whichever way I go, but since SDAs are fairly plentiful, I thought, why not get the best model and forget about settling for a re-worked simulation. I might just do both at some point, If my wife doesn't divorce me and take the house for being an audio packrat! My 2Bs are still in my shop getting a cosmetic makeover and will soon be ready for a "TL" treatment, if you are still willing to "recap" etc. the XOs for me ! gdb:)

ben62670

No problem. Send them down. We can take a look at the XO's, and get a parts list ahead of time to keep down time to a minimum.
Ben

F1nut

the more I'm wondering if I should hold off on upgrading my 1As and try to find some 1Cs

Didn't I answer that one already?

You have my cell number, feel free to use it.

altecman

Why don't you carry out the SDA-1A.1TL Modification I posted earlier, I know Aussies speak a little different but it's still basic English. You won't have to worry about people saying that their 1C's are better than your 1A's because it's not a 1A anymore but better. I personally think it's a better design due to having only one tweeter.

ben62670

You know Its personal preference.

dcmeigs

I did the 1A upgrade that Altecman describes with excellent results. If you search, you will find the thread. One thing I'd like you to consider is that the 1A crossover has fewer and smaller caps making the upgrade much less expensive than that for the 1C.

Given that caps are sold by the microfarad, the upgrade to the SDA-1A, with it's simple crossover, is a lot of bang for the buck.

altecman

dcmeigs wrote: »

I did the 1A upgrade that Altecman describes with excellent results.

dcmeigs, Thanks for having the courage to do this mod, hopefully others will follow. What was the most noticeable thing to your ears after completing this mod, this is for the sake of others who might be interested. The idea of doing this was to make good out of a speaker that has been ignored in favour of the later editions and with some minor mods will produce a fine sounding speaker. Whilst this mod might be easy for DIYers like us, I will attempt to photogragh the steps required but not until I receive the RDO194s - having too much fun listening to them now to pull apart to photogragh.
Polk SDA's are not that common in the land of Oz, I am wondering if you know someone who has a pair of 1C's, it would be great to compare the two. I suppose my next level of modification will be panel damping of the enclosure (clean up a little bit of the midrange fuzz), not sure yet what to use as I don't want to reduce too much internal volume, it will be either lead or that stick on sounding proofing stuff you put on the inside of car doors.:D

dcmeigs

I'm not sure there was much courage involved but I do think the SDA effect is harmed by involving the high pass (tweeters) in the dimensional array. Simply unplugging one wire from each array tweter is all it takes for one to evaluate this for themselves and I recommend that anyone with an SDA-1A should pull a wire and give it a listen. Afterall, personal preference is involved here.

I did this quite a while ago and I can't recall coming to a detailed understanding of why I didn't like (and decided to sell) the 1A's, but I found the SDA effect to be annoying, busy and unfocused while I find 2Bs to be pleasant and focused. The mod fixed that problem and made them sound 2B-like.

BTW, I decided not to center the tweeter because I didn't want open the baffle as I was concerned that it was needed to separate the low pass array drivers from the stereo drivers. I did use a 198 tweeter and I think that is a key improvement if you start with 2000s. I'm imagine the 194 is much the same.

Another positive about the 1As that I mentioned above is that the cost to recap the crossovers is quite modest in comparison to some of the others. The 1A can make for a very fine budget speaker.

Photos are at post 100 (way-threadjacked) here.

dcmeigs

dcmeigs wrote: »

I did use a 198 tweeter and I think that is a key improvement if you start with 2000s. I'm imagine the 194 is much the same.

No, that's not correct. I used the 194s on the SDA-1As. To good effect.

ben62670

The 194, and 198 are the same tweeter with different windings on the VC thats it.
I did the single tweeter mod on my 2's long time ago. Much better than stock;) I loved how some of the members were saying you can't do that, it wasn't designed that way... One benefit of the old 1's is that the 2 lower woofers are bass only, they have one stereo mid driver, and one dimensional mid driver.
Ben

treitz3

treitz3 wrote: »

Wasn't the ohm rating different between the two as well? IIRC, the 1A's were 4 ohm and the 1C's were close to 6.

I'll answer my own question. Yes they were.

altecman

dcmeigs wrote: »

BTW, I decided not to center the tweeter because I didn't want open the baffle as I was concerned that it was needed to separate the low pass array drivers from the stereo drivers. I did use a 198 tweeter and I think that is a key improvement if you start with 2000s. I'm imagine the 194 is much the same.

dcmeigs
I am sorry for thinking that you carried out this 1A.1TL mod, I also tried disconnecting one tweeter but the problem still remained, that is, the tweeter wasn't projecting correctly as it was jammed in a corner - so much edge deflection, I just wasn't hearing enough of the tweeter. Another step you forgot to mention is that the xover has to be modified as stated in the SDA-1A.1TL Modification thread, if not the single tweeter will be too attentuated.
The vertical brace in the middle of the baffle is just a brace as there are so many holes cut out in the baffle that something was needed to support it. This brace has no effect what's so ever on the low pass array.