That mystery cable

[Polk65]

Something about the cable mentioned in two FM threads (photo 1) bugged me until I looked at the RTA 12 connector (photo 2). It is quite similar, and also appears similar to the outside of gkouvaras's (http://www.polkaudio.com/forums/showcase/view.php?userid=48506) SDA 1's (photos 3 and 4).

Any thoughts ?

[F1nut]

Hmmmmmmmm???

[RuSsMaN]

Come on Guru, lets have it, whats the deal?

[Dennis Gardner]

Headline News...................


Fossil discovery indicates experts don't know all they thought. Missing link?

[Polk65]

Found another...

Remember our buddy in Colorado that parted out the SDA 1's last year?
http://www.polkaudio.com/forums/showthread.php?t=30454

[dorokusai]

Do you see a pattern here? It's still 99% unuseable.

It's the same termination used on RTA12's for the crossover assembly.

[Dennis Gardner]

The pattern is that Polk has always used whatever parts they had available on the market for their models until they needed a larger run than the existing inventory could support, or issues with design required change. Its called evolution.

This is found on all levels of industry, when inventory over/underruns require change in the model run.

We just shouldn't be trying to discredit sellers on auction sites for what we don't have full knowledge of ourselves.

[dorokusai]

The pattern is the model number, early SDA1. The tweeter is a notorious, common variation amongst Polk's, as the documentation for the early stuff is all over the place(e.g. RTA12). This interconnect is just a red herring.

[hoosier21]

I gotta say, I just learned something.

Interconnect cable types:
1. Blade-Blade
2. Pin-Blade
3. AI-1 (pin-blade)
4. Ken S's homebrew AI-1 (blade-blade)
5. Now this RTA12crossover connector, SDA cable.

Anymore?

[Dennis Gardner]

Don't forget Raife's Vampire 5way and XLR editions. :D

SDA Upgrade Thread. (http://www.polkaudio.com/forums/showthread.php?t=30467&highlight=xlr+cable)

[F1nut]

Russ, I'd have to agree with what Mark said, "It's still 99% unuseable."

[hoosier21]

Russ, I'd have to agree with what Mark said, "It's still 99% unuseable."

Not sure what either of you two mean by that, the photos look like the connector was factory installed, the cable matches, what is unuseable about that? Am I missing something here?

[Dennis Gardner]

It just won't fit anything but those few models. 99% of the SDA line uses other types.

[hoosier21]

It just won't fit anything but those few models. 99% of the SDA line uses other types.

Well maybe that's what they meant, but big effing deal it won't fit 99% of the SDAs out there, it looks like there was SDA speakers made that this cable will fit.

Jesse posted a big warning on the FM that "This is NOT a Polk Audio SDA cable." http://www.polkaudio.com/forums/showthread.php?t=37926

Not blaming Jesse for posting the thread, as we all thought when we saw a connector that was not "blade-blade" or "pin-blade" , that it was a hack job, something "some idiot" did to the speaker.

Well it looks like to me there are photos showing this type of connector and this type of cable WAS used by Polk.

This thread was started to kind of clear the air, that there seems to be an early version of the SDA cable, to me it has done that.

[Dennis Gardner]

Is this what happens when we assume?

[F1nut]

This thread was started to kind of clear the air, that there seems to be an early version of the SDA cable, to me it has done that.

Agreed. Another part of Polk history has been unearthed.

[F1nut]

Thanks to Steve for uncovering this mystery.

[RuSsMaN]

Hilarious.

[Polk65]

I started this thread hoping to learn if this was a genuine cable and it appears that it was used prior to the blade/blade cable.

The one thing these speakers share in common is that they are all SDA 1's. These came out around what, 1981/1982 ? That places these right around the production time of the RTA 12's.

Here are a couple more. I might add, that if it was not for the fact that some recent photos appeared with close-ups I would never have made the connection.

edit: I moved the three rear photos below.

[Dennis Gardner]

The carpet in the middle photo screams bell bottoms and disco balls. :eek:

[Loud & Clear]

It was assumed that the guy selling was guilty of passing off a hack job to an unsuspcting public. It seemed a fair assumption at the time. Ultimately, it appears as though that has been disproven, and that the gentleman in question was simply offering up for sale a genuine Polk SDA interconnect; albeit for a limited potential clientele.

[F1nut]

Come on Guru, lets have it, whats the deal?

Here's the deal, you didn't know, I didn't know. Steve did some digging and thanks to him, now we all know. I would rather be wrong about something like this than see a fellow Polkie get ripped off. You didn't seem to care about anything except for not having something you didn't like being posted in the FM. So, let's have it, what's the deal?

[RuSsMaN]

blah blah blah.

You'll argue about anything Jesse. Do whatever you have to, post whatever you have to, for your ego to stay intact - that's all I am concerned with anymore.

[Polk65]

Here are three more, front.

[Polk65]

The above three, rear.

[Polk65]

This is a later model with the inter connect in the same location, but with a blade/blade cable.

[Polk65]

Who can spot what else is different with the later version?


edit: No more nagging please! There is nothing new about Polk doing things differently during product runs.

Jesse did the right thing warning members (new and old) with the knowledge that was known at the time.

There have been several hack jobs using xlr cables...

[dorokusai]

Well maybe that's what they meant, but big effing deal it won't fit 99% of the SDAs out there, it looks like there was SDA speakers made that this cable will fit.

Well it looks like to me there are photos showing this type of connector and this type of cable WAS used by Polk.

This thread was started to kind of clear the air, that there seems to be an early version of the SDA cable, to me it has done that.

Big deal it won't fit? It might be a big deal if it doesn't fit what you own, and you bought it under the assumption that it would eh? The Ebay advertisement doesn't specify a model and is at the very least, misleading. The associated model(s) are ancient and if they haven't made it to the graveyard or dump, it's borderline amazing.

The linked historical thread and pictures were all but forgotten until now.

[madmax]

Oops... :o
madmax

[F1nut]

blah blah blah.

You'll argue about anything Jesse. Do whatever you have to, post whatever you have to, for your ego to stay intact - that's all I am concerned with anymore.

I'm not the one attacking or agruing about this topic. I'm glad that the correct info has come to light, too bad you don't feel the same way.

Oh and Russ don't kid yourself, when it comes to egos, no one's is bigger than yours, period.

Now bugger off.

[RuSsMaN]

Thanks for validating my point, I knew you couldn't resist.

Cool, we found out what it is, great, I'll sleep better tonight knowing that.

[hoosier21]

Big deal it won't fit? It might be a big deal if it doesn't fit what you own, and you bought it under the assumption that it would eh? The Ebay advertisement doesn't specify a model and is at the very least, misleading. The associated model(s) are ancient and if they haven't made it to the graveyard or dump, it's borderline amazing.

The linked historical thread and pictures were all but forgotten until now.

I agree, it won't fit 99% of the SDA speakers out there,

I started this thread hoping to learn if this was a genuine cable and it appears that it was used prior to the blade/blade cable.

Thats how I read it from the beginng, my comments on this thread have nothing to do with that auction or how MANY speakers this type of cable will fit.

[F1nut]

Validate what Russ? That you keep attacking anything I say? That you act like a spoiled little child? I don't have to validate any of that, you do a fine job all by yourself.

[ohskigod]

I guess the next mixed martial arts match is set for polkfest :D

[dorokusai]

Crouching Coif, Hidden Vomit

[BobMcG]

Thanks Steve for the great info and photos on a missing SDA link. Never knew about it to be sure.

[steveinaz]

Crouching Coif, Hidden Vomit

ROTFLMAO!!!!!!!

[Polk65]

Who can spot what else is different with the later version?


Here is the difference I am curious about. Was there a pair of ports underneath the tweeters in the earlier model?

[DarqueKnight]

The SDA 1 manual says the four midrange drivers operate as a "fourth-order vented system".

A fourth-order (vented) enclosure is a sealed enclosure with the additon of a port tuned to a specific frequency. The purpose of the two small ports is to extend the low frequency response of the sealed enclosure in order to provide a lower cut-off frequency. The trade-off is that some transient response is sacrificed to achieve bass extension.

[ESAVINON]

Isn't it great that we have raife and ken to sort these things out for us? I sure do think so!

[DarqueKnight]

It's even better when you can catch a word or two from Matthew Polk. Here is what he had to say:

"In the original SDA-1's there were 4 drivers. Two of these were dedicated to producing bass and driving the passive radiator. The other two drivers, one for producing the stereo signal and one for producing the SDA Dimensional signal, had their own enclosures which isolated them from each other and from the bass drivers. The small vents did help blending to the bass drivers but did not really "tune" the mid-band drivers. They were really more of a pressure vent to prevent buckling of the mid-range driver cones when driven hard.
-msp"

[Toka78]

Missed this thread the first time 'round somehow, but wanted to add that my SDA 2's have the same 'mystery' interconnect (as well as dual SL-1000's). I bought them from the original owner, who was 'pretty sure' he bought them 'in 1984 I think'. Take that for what you will, but it does look like they made it onto more than one line.

[Lasareath]

Is this what happens when we assume?

Yes, we make an Ass out of u & me!

[Gary Batson]

My SDA1's have the same interconnect cable in question. It's a pin pin connector with a plastic socket that locks in place when its plugged in. Mine appears to me to be a better quality connector than ALL the other connectors. How's that for ego? :D

[Boywonder]

For future reference, if anyone stumbles across this post in need of one of these IC cables, the plugs and crimp contacts to build an IC cable for these early SDA-1's (or for the HF tweeter module for an RTA-12) are AMP parts and are available from Jameco.

The connector is called an AMP snap-lock circular plastic (CPC) connector, also known as an AMP econoseal connector. The plugs are $6.49/ea at Jameco Electronics. You also need to order crimp socket contacts, and have a crimp tool for these connectors. The crimp contacts can be ordered individually. They should be quite inexpensive, even gold plated (if that's an option). Nickel plated contacts are 30 cents each and gold plated contacts are 99 cents each.

The Jameco P/N is 839017 and the AMP P/N is 207567

According to Jameco, compatible contacts are 66100-6; 66101-1; 66580-2; 66590-1; 51565-2 These various P/N's probably represent different plating, wire gauge, and whether they are for manual crimping or machine crimping.


The max wire insulation size for these connectors is .100" according to the drawings, but if you pop out the rubber sealing booties, much larger wire insulation will fit.

[Face]

Bad link Boywonder.

[Boywonder]

Sorry about the bad link...I just modified the post to include the Jameco and AMP P/N's instead.

[ShinAce]

Didn't read all replies, but I did see Boywonder's:

Yes, that is a military connector. Amphenol makes them(expect to pay $ 10 a piece for the 3 pin).

There are different diameters of connector available. That seems to be the larger diameter(maybe 1 inch) with only 3 pins. The 3 pins we used to sell were smaller(maybe 5/8" inch).

[peppoman]

Does anyone have the schematic (or PDF) for the cross connection inside the cabinet ?
I can make a cable with the right gauge wire, but my knucklehead brother pulled off
the terminations for the +, - and G_ on each speaker.

Thanks

[peppoman]

Oops, the question about the crossconnect above is to SDA-1's

[schwarcw]

Welcome to the Club Polk Forums pepoman!

Look Here (http://www.polkaudio.com/forums/showthread.php?t=55888)