Mismatched SDA-2B speakers?

jtkorb

I have a pair of SDA-2B speakers (not 2A, as I originally posted on 11/2/15). I bought them new circa 1989 at a local, but now defunct, audio store. I used them at my old house for 10 years with the interconnect cable that came with the speakers. After I moved, the new speaker location made the interconnect cable inconvenient, so I didn't connect it. I used them for 15 years in that configuration.

With some home remodeling being done, I now have the opportunity to hook the speakers back up in the right way--with the interconnect cable. Unfortunately, the original cable is gone (it got recycled by mistake). So, I'll make one myself. But, get this: The left speaker is blade/blade and the right speaker is pin/blade.

I opened the cases. The interconnect sockets are not wired the same. On the left speaker, the upper blade is unconnected; on the right speaker the blade is connected to the negative external binding post.

Can I make these work in SDA mode? (I'm wondering if they ever did!) I'm guessing that the original cable was a hack that connected the pin on the right speaker to the lower blade on the left speaker.

Speaker specifics...

LEFT (blade/blade, upper blade unconnected):
Cabinet serial number: 18675
Crossover board date: 4/25/88

RIGHT (pin/blade, blade connected to speaker ground):
Cabinet serial number: 16650
Crossover board date: 10/24/88

Thanks for any help or advice.

Tim

[Deleted User]

Hello,
To say that was unusual would be an understatement. When you did have the SDA cable was it spliced in some way? Without seeing the crossovers it's hard to advise what you should do.
Since the twin/blade cable is the one that Polk CS can supply it might be best to try and bring both speakers to that configuration. But, it would be important to make sure your amplification source is compatible with a common ground speaker connection.
Regards, Ken

F1nut

Left: What is the lower blade connected to?

Right: What is the pin connected to?

jtkorb

Ken: Unfortunately, I don't remember what the IC cable looked like. I don't recall any splices, so I think it was just asymmetric, with different connectors on each end.

F1: All three wires from each rear plate of each speaker are connected to a three-pin connection on the crossover board labeled "INPUT". The left speaker lower blade and right speaker pin both have blue wires going to the pin labeled "I.C." on the "INPUT" connector. The other two wires (black and white) from the rear plate connect to the other two pins on the INPUT connector. (The right speaker just has a white jumper going from the blade to the negative speaker terminal.)

I can upload pictures if it would help.

Tim

Nightfall

A bit off topic: You listened to them without the interconnect for 15 years???

westmassguy

You should replace both IC sockets with SpeakONs, and make a new interconnect cable with SpeakON Plugs. This will solve all your problems, and you can use a much higher grade speaker wire for the new interconnect.

westmassguy

They'll look something like this:


You can also upgrade your Binding Posts while you're at it.

F1nut

All three wires from each rear plate of each speaker are connected to a three-pin connection on the crossover board labeled "INPUT". The left speaker lower blade and right speaker pin both have blue wires going to the pin labeled "I.C." on the "INPUT" connector. The other two wires (black and white) from the rear plate connect to the other two pins on the INPUT connector. (The right speaker just has a white jumper going from the blade to the negative speaker terminal.)

Ok, the right speaker is wired correctly for the SDA 2B pin/blade model. The left speaker is wired correctly for the SDA 2B blade/blade model. Therefore, as long as the SDA cable is wired to the pin on the right speaker and the small blade on the left speaker you will have the proper SDA connection.

However, the way the left speaker is wired right now, you would not be able to use the AI-1 or Dreadnought isolation transformer for use with non-common ground or mono block amps.

Although Polk still sells a blade/blade SDA cable they do not sell the blade/blade socket. Therefore, the best idea would be to replace the sockets. You can do this by replacing them with Neutrik SpeakOn female sockets and use the SpeakOn male connectors for your new SDA cable.

While doing so you should duplicate the right speaker white wire connection on the left speaker. This would allow you to use the AI-1 or Dreadnought isolation transformer in the future.

jtkorb

WMG and F1: Thanks for the pictures and advice. I will start with the SpeakOn parts and new interconnect cable and wiring.

Also, how do I deal with the goop on the connections? Is that hot glue?

westmassguy

The back of the binding posts is sealed with hot glue. I use a small, sharp chisel, and just lift it off. The old pin/blade connector is glued from behind with a black solvent glue. Take a 1/8" drill and drill out the pop rivet heads on the face, then take a channel lock, and just break off the old connector from behind. you'll need a Dremel, multi-bit, or rotary rasp to enlarge the hole for the SpeakON.

F1nut

Drops of denatured alcohol on the glue will cause it to lose adhesion and be peeled off with ease.

Be sure to use the 4 pole SpeakOn's even though you will only use two poles. The 4 pole versions built better and are air tight.....very important.

gimpod

F1nut wrote: »

Drops of denatured alcohol on the glue will cause it to lose adhesion and be peeled off with ease.

Hot Glue How To Remove It

Jesse just checked the 2 pole SpeakOn connectors are air tight also. Just make sure to get the gasket for it, it's the same one used with the 4 pole connector.

F1nut

I know some of the versions are labeled not airtight, so best to read the description closely.