SDA ALS - 2 binding posts and amps.

kenai

Hi All - acquired a set of SDA/SRS speakers and 2 sunfire amps. Each speaker has only 2 binding posts; not the 4 per speaker you would see for bi-wire/amping. Since these speakers benefit from more power what is the best way to connect these amps to the speakers?

pitdogg2

Current delivery amp binding post.

Which Sunfire amp?

F1nut

kenai wrote: »

Hi All - acquired a set of SDA/SRS speakers and 2 sunfire amps. Each speaker has only 2 binding posts; not the 4 per speaker you would see for bi-wire/amping. Since these speakers benefit from more power what is the best way to connect these amps to the speakers?

Post a pic of the front without the grill and one of the binding post plate.

kenai

Okay progress. Here's some pics. Got binding post sorted. Un- jumpered the binding posts. The top binding posts are voltage source. Sound was very very weak on top. Is there a resistor -that with age could be - protecting these tweeters. Something is amiss.

Seems I remember there being a big upgrade possible on the tweeters. What was being used/availability?

pitdogg2

Each speaker has only 2 binding posts; not the 4 per speaker you would see for bi-wire/amping.

They seem to have 4 binding post, it also appears you are bi-wiring. Unless you want to get into them and do some crossover work the tweeters you would buy from Polk are RD-0194 model. If you wanted to turn those into a TL model, there is different crossover work to be able to use the RD-0198 model tweeter.
The RD-0194 tweeters are a drop in model for your speakers. The RD-0198 tweeters are not a drop in model.
Either way I'd highly recommend a recap and new resistors and do away with the polyswitch which are nasty and may be causing some problems at this late time by causing a drop off in the tweeters or cutting in and out.

kenai

Yes these are biwired; mix up with some Carver ALS that have only one set binding posts. Where are the polyswitches located? Are RD0194 available?

kenai

Located the tweeters, now I need to bottom the polyswitch issue. Where are these located? in crossover?

pitdogg2

you're looking for something like this. YES they are on the XO board. Most folk have removed them and replaced with a 1/2 ohm 12 watt resistor. Vashay-Mills mostly.

michaeljhsda2

Is the interconnect socket pin/blade or blade/blade? I can't quite tell by the pic. If it's pin/blade, they are SRS 1.2's but here's the problem...the label on the back is from the original SRS which shows the positive (red binding post nut) on the right. But since your speakers may be 1.2's the positive should be on the left and black on the right. Additionally since they are wired wrong, they are out of phase which will really diminish the bass response among other things. History has shown that Polk didn't want to waste any parts so they used the label from the SRS's and put them on the 1.2's and 1.2TL's. You can confirm by removing the binding post cup and note where the positive wires are going. Instead of swapping the wires on the inside of the binding post cup, it's easier to just swap the red and black plastic nuts.

If it's a blade/blade IC socket, ignore all the above.

michaeljhsda2

Label for the SDA SRS 1.2 and SDA SRS 1.2 TL

pitdogg2

I thought theblade/Blade was outside the cup.
I do see where you're coming from as those do appear to have a blade/Blade socket.
Very hard to tell

michaeljhsda2

Pretty certain that the 1st generation (original) SDA SRS has the IC socket within the cup.

F1nut

My eagle eyes say blade/blade.

kenai

Hi All - back after a pause; we have had exceptional weather - today is 50F. Here is more pics. The close-up of the post shows a hole thru the center; so I am guessing this is post and pin type binding. Next pic is inside. Wire from red post had a red marker tape on each end. Red wire goes to xover and there is letter "R" next to it on the board. Take this to mean it is for the red /positive wire. The black post-wire connected at far end of board. Backside of binding-cup had sticker "December 1985". Near the red connection point -at the board- notice light blue rounded gizmo. Is that the polyswitch?

So which speaker do I have? I can shoot more pics to clarify. Thxs in advance

kenai

here is board pic

pitdogg2

Near the red connection point -at the board- notice light blue rounded gizmo. Is that the polyswitch?

Yes!

I cannot recommend pins through the hole in the binding post. The hole is for bare wire. YOU could use a pin but it would not make very good contact. (My personal opinion)

JayCee

kenai wrote: »

Backside of binding-cup had sticker "December 1985".

So which speaker do I have?

You have the original SDA-SRS's...not the later 1.2's. Confirmed by the date you mention, pic of the XO board which has large inductors mounted on the sides of the board and blade/blade SDA interconnect socket. Also, pretty sure the label on the board is '85 but regardless of the labels...they are the first iteration SDA-SRS and the only replacement (upgrade) tweeters you can use are the RD0194. RD0198 are only compatible w/the 1.2's.

F1nut

As stated, those holes are for bare wire, which is never a good choice.

One of your binding posts has some sort of hack repair job. The stock posts were not of great quality to start, so all should be replaced.

The copper wire in the clear jacketed chassis wire inside your speakers is turning green. All should be replaced.

The black caps with red ends are Temple caps, which are real crap. There's tons of info in here on crossover upgrades and all the other recommended SDA upgrades, so get your search on.

LisaBen

Why is bare wire not a good choice?

Clipdat

Because you're a bot?

F1nut

LisaBen wrote: »

Why is bare wire not a good choice?

For starters, when raw copper wire is exposed to oxygen it oxidizes and oxidized copper is a very poor conductor.

F1nut

Here's a visual for you.

LisaBen

Clipdat wrote: »

Because you're a bot?

Do you call anyone new that? Sorry for daring to speak.

audioluvr

Don't mind him, he's an ****

kenai

Polys out and RDO194s in. //Unbelievable// improvement. Top end really comes alive.
Looks like replacing the large SDA inductors has a lot of bang for the buck for improving the sound. Thoughts?

audioluvr

Yes, they make a noticeable improvement.