The SDA Effect issue

Mr. Sharpe

as some already know my dad picked up a pair of SDA 1A's from a thrift shop up the road. I have just today hooked up the SDA interconnect cable, it looks at though this cable is polarized (one small and one large blade), when I plugged this in I noticed that one is hooked with the large blade up and small down.

Here's the dilemma, one speaker sounds incredible, the other I believe the SDA tweeter and woofer are either blown or I've hooked them up wrong. I don't want to try forcing the plugs with large blades facing the same way because they will not go in and I don't want to blow up his amp. Surprisingly this little integrated amp sounds wonderful especially for the size room he has.

I really do hope they aren't blown... then again he only paid $60 for them, if new drivers are needed I don't think it'll matter much.

pitdogg2

Check fuse if it has one clean fuse holder. Blade/blade is pretty hard to hook up wrong. Many folks get inside and try to make them "normal" speakers check wiring inside.
The wiring interconnect inside is reversed from the left to right speaker so do not think you will be "fixing" it to make it the same on both. That might just let the magic smoke out of the amp or speaker. Is the cord loose in the socket then spread put the blades a little see if it helps.

Mr. Sharpe

the connection is plenty tight. If the interconnect is reversed inside that would explain the large blade being on the bottom on one speaker and top on the other.

is the fuse inside the rear terminal?

F1nut

The cable sockets are exactly as they should be. Your problem is elsewhere.

Mr. Sharpe

I pulled the PR and didn't see a fuse anywhere. both the drivers read 8ohms and continuity. I don't know what the deal is.

I'm sure they'd be worth recapping...

gimpod

Mr. Sharpe wrote: »

the connection is plenty tight. If the interconnect is reversed inside that would explain the large blade being on the bottom on one speaker and top on the other.

is the fuse inside the rear terminal?

To begin with there is no such thing as an "SDA Effect". The simplest way IMHO to explain SDA's without going into a bunch of techno speak is to think of them as headphones for your living/sound room. Here's a post about it Thoughts on SDAs

According to the SDA 1A Schematics your SDA's don't have external fuses but a pair of polyswitchs per speaker one each for the high and low pass section of the crossover. This is the most likely culprit as they like to fail over time, You can bypass them for testing purposes but if they are bad I would replace them in your case.

Hope this helps.

Mr. Sharpe

That is very informative! And really cool to read something about what the SDA actually is.

It would be very well worth bypassing, i'm guessing the value would be written on the switch then? if so just tie a wire on either lead of the switch to create a signal between yeah?

F1nut

Twisting the polyswitch leads should be a temporary thing, very temporary as that makes for a crappy connection. Removing them and soldering in a jumper is the proper way.

Mr. Sharpe

Sounds like a plan sir's, thank you for the helpful replies! These speakers sound amazing, like I'm surprised at how good they sound, we have the volume at an average 85 db and are incredibly smooth, the low end is so clean to where it sounds like stated above, I'm listening to music through headphones.

gimpod

That's nice to hear IMHO there's nothing like listening to SDA's!.

Like @F1nut said twisting the polyswitchs is only a temporary fix, but in your case seeing how your driving them with a "little integrated amp" (I'm assuming low watt & current) I would just replace all of them in both speakers at $0.49 each why not.

Here's a link to the ones for the SDA 1A's RXEF050 0.50A Polyswitch

gimpod

gimpod wrote: »

According to the SDA 1A Schematics your SDA's don't have external fuses but a pair of polyswitchs per speaker one each for the Stereo and Dimensional Hi-Pass sections of the crossover. This is the most likely culprit as they like to fail over time, You can bypass them for testing purposes but if they are bad I would replace them in your case.

Hope this helps.

Fixed it, my bad the polyswitchs are only used for the tweeters.

Mr. Sharpe

It's an 80w per channel amp, not that little, sounds surprisingly good but of course dad wants 400 per channel.... I understand wanting headroom and all but....

soundfreak1

From my experience 80 watts won't even get their attention! Start at 200 and go from there!

Mr. Sharpe

Will do:)

K_M

To the OP, have you thought about Replacing Caps in tweeter circuit, or was that mentioned?

One of our vintage Pairs, when purchased sounded almost as if one tweeter was bad, but after replacing the cap, turned out it was just the cap had gone astray.
2nd the idea of the Polyswitches.

Mr. Sharpe

I have considered that yes sir bc neither driver is bad.

Montoya

I have a similar issue one of the SDA tweeters is not working on a pair of SDA 1 with the two fuses in the back. Tried swapping tweeters the problem stays with the speaker the fuses appear to be good. Didn't think about possible corrosion on the fuse holders maybe that is it.

pitdogg2

Montoya wrote: »

I have a similar issue one of the SDA tweeters is not working on a pair of SDA 1 with the two fuses in the back. Tried swapping tweeters the problem stays with the speaker the fuses appear to be good. Didn't think about possible corrosion on the fuse holders maybe that is it.

You using the interconnect cable?

Montoya

Yes I am using the interconnect cable.

pitdogg2

Test fuse with dvm or continuity tester. That wire is so small it is very hard to tell at times. Still I would clean holder and check wires inside. Wire corrosion could also be the culprit.

Mr. Sharpe

I have had problems with corroded volume pots on my amps... they are bothersome