What SDA's are these??

halo71

Never seen these before.

Tony M

Wow, that's a pair for the museum..


I bet they sound good also.

Toolfan66

It has a ported tube as well, I would like to know the facts behind them. has to be a prototype,,

dorokusai

Very early SDA2....they usually have a brass plate covering the "port" that had something like signature edition stamped on it. I don't know a lot about them but the driver configuration can vary quite a bit in this series.

Toolfan66

Why would they put in a ported hole then cover it with a brass plate??

Jer.War

What a cute looking speaker cable feeding them...LOL
Just kidding, how do they sound??

Conradicles

See something new everyday!

gwg_97

I'd keep those cats away from your grills!

Very interesting SDAs.

Joe08867

Wow!! those are even older than my SDA2's. What the heck is with the tweeters being stacked. That's a new one for me.

halo71

These belong to a member at AK. He bought them for $40. I was intrigued by them, thought I would ask here.


12 ohm??

heiney9

TOOLFORLIFEFAN wrote: »

Why would they put in a ported hole then cover it with a brass plate??

Because it wasn't needed anymore. The early models with the brass plate covering the hole were called "Signature Edition".

I have never seen an SDA with the tweeters on top of each other and offset in that manor. But as Doro saaid, there was a lot of variation in the original SDA models, as they were tweaking the design. I'd almost bet some type of prototype that probably very few exsist.

H9

pitdogg2

well played for 40frogskins

Schurkey

First thing crossing my mind:

Not a prototype, just an owner-designed kludge fitted into an otherwise-ordinary speaker cabinet.

Similar to all the folks who replace the passive radiator with some screwy active driver.


I suppose someone at Polk could provide details on prototype/experimental speakers.

Joe08867

I keep looking at them an thinking they can't sound good set up that way. Mid Driver next to the tweeters that are stacked probably dimensional under the stereo. I don't know what to think anymore.

They are like Polk's own version of Frankenpolk's.

heiney9

Schurkey wrote: »

First thing crossing my mind:

Not a prototype, just an owner-designed kludge fitted into an otherwise-ordinary speaker cabinet.

Similar to all the folks who replace the passive radiator with some screwy active driver.


I suppose someone at Polk could provide details on prototype/experimental speakers.

They sure modified a lot of space and it looks pretty good for a mod. That cabinet is shorter than a typical 2A cabinet with 3 drivers. Atleast it appears to be shorter in the photo, which can be decieving.

H9

heiney9

Maybe a modification of a pair of RTA 12's, the early RTA12's with the shorter cabinet. Those are not typical SDA2 or 2A cabinets, they are too short. Even if you moved the left driver up where the tweets are now, there's no room to mount the tweets. It seems the PR is mounted higher in the baffle than most pics I see of original SDA 2 and 2A's. That's why I'm thinking the short RTA12 cabinet.

Could very well be a one off Polk prototype SDA.

H9

Joe08867

I think they are about the same size just the placements of the tweeters, drivers and PR are weird.

Here is a pic for comparison.

heiney9

Joe08867 wrote: »

I think they are about the same size just the placements of the tweeters, drivers and PR are weird.

Here is a pic for comparison.

Look how high up the PR is in the Op's photo, also no matter how you rearrange the drivers in the Op's photo there is no room for the tweets in the trad. side by side config.

H9

audiocr381ve

heiney9 wrote: »

Maybe a modification of a pair of RTA 12's, the early RTA12's with the shorter cabinet. Those are not typical SDA2 or 2A cabinets, they are too short. Even if you moved the left driver up where the tweets are now, there's no room to mount the tweets. It seems the PR is mounted higher in the baffle than most pics I see of original SDA 2 and 2A's. That's why I'm thinking the short RTA12 cabinet.

Could very well be a one off Polk prototype SDA.

H9

Easy way to find out is to check and see if they have SDA interconnect terminals.

heiney9

audiocr381ve wrote: »

Easy way to find out is to check and see if they have SDA interconnect terminals.

Which they would if they are as I strongly suspect. A one off Polk prototype SDA2 of some sort.

But, yes if they don't have the SDA terminals then perhaps it's a creation by a hack. But I really don't see how they could have modfied it like they did and still make it look unmolested. Unless someone is very good with wood/vinyl/particle board repair, or photo shop, etc

H9

heiney9

Look at joe08867's photo he posted of SDA 2A's. Someone tell me how you can manipulate those drivers to get the same config as the Op's photo without doing extensive fill work to cover up gaping holes.

Joe08867

There is no way without totally rebuilding the baffle.

halo71

audiocr381ve wrote: »

Easy way to find out is to check and see if they have SDA interconnect terminals.

They do have the IC.


I would also assume these are not "one offs" as Mark alluded to the fact that they are very early SDA2's. And I have seen other pics and it mentioned before here at CP about the little port that had the brass cover. I would also assume these early ones sound like **** since apparently Polk changed the driver layout early on.

btw....they are 39 1/2" tall.

dorokusai

I sent an email to Engineering to ask about some more particulars. Keep in mind that there were a handful of baffles made for the SDA2 around this time, including the "Signature" model that included the brass plate and port. There's no need to try and visually figure out how they constructed one array or the other as this was an experiemental time for Polk Audio. There are a bunch of one-off models, short runs and oddities during the SDA years that still exist but most prototypes were destroyed much as they are today.

Unless someone from Polk snagged them up or they were given to someone as a courtesy, they usually ended up in a dumpster. I've seen dozens of cool prototypes and one off models in my short time here get sledgehammered and busted up for the dumpster. A few were alledgedly saved but we'll never really know their true fate huh? :biggrin:

halo71

Damn how cool would it be to see those before they get crushed!:biggrin: Mark, did you notice the pic above....12 ohms?

Anyway here are a few more pics of the innards....:biggrin:

dorokusai

Halo - Yes, that's odd indeed and I asked about that as well. It's very unique to say the least. I've never seen a pair aside from these and only ran across a couple pairs of the brass plaque models. I had a chance to buy a pair but passed since they were physically a complete mess and needed too much work. I took a pic and posted it here...somewhere.

heiney9

halo71 wrote: »

They do have the IC.


I would also assume these are not "one offs" as Mark alluded to the fact that they are very early SDA2's. And I have seen other pics and it mentioned before here at CP about the little port that had the brass cover. I would also assume these early ones sound like **** since apparently Polk changed the driver layout early on.

btw....they are 39 1/2" tall.

The defining feature to these is not the port, but the stacked and offset tweeters. Goes against common SDA theory. I'm still guessing one off prototype.

H9

FTGV

heiney9 wrote: »

I'm still guessing one off prototype.

H9

If I were a betting man I would agree,those baffles look to be factory routed for that driver positioning,not an after thought by a would be modder.

heiney9

FTGV wrote: »

If I were a betting man I would agree,those baffles look to be factory routed for that driver positioning,not an after thought by a would be modder.

They certainly are interesting looking. Probably don't sound that great if they are wired like a typical SDA. Perhaps they are wired differently.

H9

heiney9

I wonder which is the left one and which is the right one?

nooshinjohn

I bet they sound better than Blose.