Goodwill find..........SDA-2/II

Bobsama wrote: »

... On3s's little hack-job, while it'll get the job done, will probably change the cabinet's properties a bit.

Why, you...

I was definitely only suggesting it as an interim measure. If when you're picking up fuses the Rat Shack or Auto Zone has disconnects that would work it might get you off to the races quicker. In my case, the blade/blade Jones sockets are just attached to a hole drilled part way through the cabinet MDF by a couple of wood screws. My sockets were already busted up so I wasn't risking doing any damage to the speaker that wasn't already done. If the type of connectors you and Bob have don't look like they would be easy to remove and later replace then I retract my recommendation.

Which brings me to a very important point... If following any advice given by any member of this forum results in damage to the speakers, we will indemnify you only up to the amount paid, and of course we'd have to take possession for salvage.

Yeah, I'd be a little careful with the crossover cable. The blade/blade interconnect is definitely a straight-through cable. My interpretation of the earliest schematics available is that since the L and R channels reverse the A and B wires to the socket pins the cable should be straight through to the plugs. A continuity test on the stock cable would tell you for sure. Unfortunately, I can't think of another way to be sure without opening the speakers or finding a definitive schematic.

If it's wrong, it will look like a short circuit to the amp, and depending on the amp's circuitry it will blow a fuse or eventually go into a protection mode until it cools down. I ain't warranting anybody's amplifier against mine or anyone else's advice. :O

cov413 wrote:

hey you responded to my post about my SDA's I got from goodwill. you mentioned yours have the same interconnect plug mine do. How did you solve the problem, I'm going to radio shack tomorrow to try and come up with a fix.

You need a pair of XLR3 jacks and a pair of XLR3 plugs. While you're there (if you don't have it already), pick up at a roll of #16 gauge or thicker copper-core bi-wire.

What you need to be aware of is that the SDA cable is NOT a low-power signal cable; it'll be carrying a significant amount of power and using the SDA effect effectively doubles your power draw on each channel. So, we shan't disregard the wires used or the quality of the connection; a spotty job soldering or otherwise securing the wire to the XLR3 jacks and plugs will be bad.

A Radio Shack brand XLR3 jack should work fine. You will need four pieces in total. Two for the wire, two for the cabinets. I'd suggest you go with Female receptacles on the cabinet and Male plugs for the wire; it'll make doing the wire a touch easier and will put the lock on the cabinets. In my experiences, having the lock on the equipment is more secure and less prone to failure than having it on the cables.

The short walkthrough for this...
1) Lay both loudspeakers on their sides on the ground or on a workbench/table. Remove the 12" passive radiators.
2) Take note of the crossovers; find the leads going to the Dimensional PCB and then follow them to the SDA receptacles. One side is Pin #1 (Output), the other is Pin #2 (Input). I don't know how to verify which is which, though I'll be finding out tomorrow, hopefully, via email.
3) Note that XLR3 Pin 1 is "irrelevant"; it's typically a grounding pin and should be treated as such. XLR3 Pin 2 is usually Output and Pin 3 is usually Return. Now, on the RIGHT cabinet, you'll move Pin #1 to XLR-Pin 2 and Pin #2 to XLR-Pin 3. So, remove the current receptacle and rewire each lead to the appropriate place on the XLR receptacle.
4) Take note again of the LEFT cabinet. This time, however, you'll want to connect Pin #1 to XLR-Pin 3 and you'll want to have Pin #2 connected to XLR-Pin 2.
5) With Mortite or a similar non-drip sealer, make a ring around both of the receptacles outer edges. You'll want to screw both in (after opening the hole, if necessary) with the Mortite acting as a gasket. Let the Mortite settle for a few minutes and then return to tighten the screws again.
6) Wire the XLR connectors. If you have or have plans to use a standard XLR cable, you'll want to use triwire here (you can probably pick some up at Radio Shack, though YMMV on finding it). Otherwise, biwire or regular speaker wire will work fine. Wire Pin 2 to Pin 2, Pin 3 to Pin 3. And if you want to use it as a standard cable, also wire Pin 1 to Pin 1.
7) Test it carefully. Start at low volumes; we don't want to overvolt AND overamp the speakers. You want to check that the Left channel audio is playing on the inner drivers of the left cabinet and the outer drivers of the right cabinet. The inner drivers are the Stereo drivers and the outer drivers are the Dimensional drivers. So long as you have it correct, the one channel will play at full volume on one channel and will sound funny on the other channel. Verify with both sides that it's working properly before you turn the volume up. You'll once again want to test it to ensure it works properly.


Remember, this is how the loudspeakers should be setup...



Alternatively, you could wait a few weeks. I'll probably do this mod on my SDA-1's and I'll be able to sell you the cable you need.

cov413 wrote: »

I found a Sansui AU-417 amp and TU-417 tuner for sale near me. Below are what specs I could find on this amp. Question is it only lists output at 8 ohms, I was told that using the interconnect cable drops the ohms down to 2. Is that true and does anyone know if this amp will properly power my speakers.

http://www.classicaudio.com/value/san/AU417.html

help please.........................

Googled a bit and found this: http://www.audiokarma.org/forums/archive/index.php/t-29821.html
"in know for a fact that you cant drive a pair of 4 ohm speakers without clipping with the au-417. had to bring the infinity speakers back to the store and get some cerwin vegas..."

Doesn't bode well. Find out as much as you can about any amp you consider and see what kind of power it can put into a 4 ohm load. (I wouldn't worry too much about the 2 ohms, the SDA's might dip to 2 ohms, but I'd be really, really suprised if they were designed to be a 2 ohm average load with the interconnect cable).

Some amps designed only for 8+ ohms can't handle 4 average without overheating or clipping. But, some amps actually increase their power into a 4 ohm load either by automatically detecting the lower impedance or having a switch somewhere on the amp. The first amp I tried with my SDA 2's was a NAD 2100. It's rated at just 50wpc into 8 ohms continuous, but according to NAD could put 250w into 4 ohms for short bursts. It worked, never audibly clipped, but the bass was thin.

I tried a 105 wpc Hafler 9180 and that was very respectable. I'm running a 200 wpc amp now and I really like the sound. For better or worse, the SDA's like power. Whatever amp you get, if you hear it start to clip, turn it down. (NAD amps also have a "soft clipping" feature where the amp will sense when it's being overdriven and turn itself down to try to avoid damaging the speakers.)

Did you ever figure out if all your tweeters are working?

Just for Bob I fixed my hack job with the proper jones socket for the blade / blade interconnect. These things are pretty damn simple to work with, so if they happen to fit in the hole that's already drilled in the cabinet for the not-quite-XLR connection then I'd say they're a pretty good way to go. I don't have a caliper or I'd give the exact diameter of the socket. The socket body is very close to 9/16 inches in diameter. There's a little pin that holds the screw bracket to the body that I had to dremel out a notch for. Otherwise just a very quick and simple solder job and screw it back into the cabinet.

For the record I couldn't tell any sonic difference between this and the hack.

The mortite's totally unneccesary in this case. The hole for the socket doesn't completely penetrate the cabinet. There is just a very tiny hole only large enough for the two 20ga wires to the socket and those are a tight fit! The speakers pass the PR push test with flying colors. But I do plan on getting some mortite for use when replacing the tweeters so I might come back to these IC sockets if I'm in an overkill kind of mood.

kchilaka wrote: »

Like the OP, I scored a pair of Minty SDA-2 speakers on CL. Came with the interconnect cable. I think I stole them but who knows what they are worth nowadays. I think they are the original SDA-2. Here is what they look like.

I tried them out yesterday with my Sony DA30ES receiver and they sound great except the low end wasn't that strong. The speakers do seem to go down low but they don't have the "slam" if you will. Perhaps I am just used to Sub-Sat combos where the sub levels are a tad high. The mids and highs were beautiful and they seems like an articulate pair of speakers.

Nice work, those are definitely in fantastic shape. The bass is a little underwhelming, but they're wicked good for what you probably paid for them. I overpaid for mine, but I really wanted to hear a pair of SDA's and $300 is the cheapest I've seen a pair go for in my neck of the woods!

Anyway, welcome to the club and to the mental derangement that is vintage Polk. For kicks, you should post asking whether you should upgrade the tweeters to the modern RD0194 replacements and rebuild the crossovers. Also, you'll now need to start shopping for some SDA-SRS to find the bass that you're missing.

Sorry, I shouldn't kid. Seriously, I hope you enjoy hearing your music on them. I love mine, they're a great and very interesting speaker.

PS: I will say one thing about the bass... the SDA 2's are a 4 ohm speaker that will handle 500 watts. It looks like your Sony does 70wpc into 4 ohms stereo. I had mine on a 70wpc NAD receiver and the bass was really poor. I picked up a 105wpc Hafler amp and it improved, but when I put 200wpc into them (with the amp plugged directly into the wall, not a surge protector) the bass just about doubled. Everyone says all the SDA's improve the more power you feed them, and from what I've seen it's definitely true.

helipilotdoug wrote: »

... These SDA's do like to be fed a healthy diet of power. I'd upgrade the amp to something that puts out at least 250 watts. More if your pocketbook can stand it.

Come to think of it, my awesome and inexpensive (relative to new) vintage speaker score wasn't so inexpensive since I wound up dropping several hundie more on an amp that could get the most out of them.

Damn you, Vintage Polk!!!

I was thinking of going the other way on this. I was planning to get a digital panasonic xr55/xr57/xr70 . These little amps have extraordinary accuracy from their digital equibit amps. They also have the ability to biamp and triamp the fronts in stereo mode. I guess I have to see if they have the guts to drive these speakers properly.

On3s&Z3r0s wrote: »

Nice work, those are definitely in fantastic [I[/I]shape. The bass is a little underwhelming, but they're wicked good for what you probably paid for them. I overpaid for mine, but I really wanted to hear a pair of SDA's and $300 is the cheapest I've seen a pair go for in my neck of the woods!

Anyway, welcome to the club and to the mental derangement that is vintage Polk. For kicks, you should post asking whether you should upgrade the tweeters to the modern RD0194 replacements and rebuild the crossovers. Also, you'll now need to start shopping for some SDA-SRS to find the bass that you're missing.

Sorry, I shouldn't kid. Seriously, I hope you enjoy hearing your music on them. I love mine, they're a great and very interesting speaker.

PS: I will say one thing about the bass... the SDA 2's are a 4 ohm speaker that will handle 500 watts. It looks like your Sony does 70wpc into 4 ohms stereo. I had mine on a 70wpc NAD receiver and the bass was really poor. I picked up a 105wpc Hafler amp and it improved, but when I put 200wpc into them (with the amp plugged directly into the wall, not a surge protector) the bass just about doubled. Everyone says all the SDA's improve the more power you feed them, and from what I've seen it's definitely true.

On3s&Z3r0s wrote: »

Ahhh... going for something a little more Mazda RX-8 than Dodge Viper? I'd be very curious to hear how you like it with the SDA's. I don't know of any way to bi-amp the SDA2's unfortunately, but it would be interesting to hear how a digital amp would work with them. You might want to check into whether they classify as a "common ground" amp, though. A non-common ground amp could be damaged by the SDA's since the interconnect creates a short between the 2 channels when those channels don't share a common ground.

I like your analogy Yup RX8 over a viper. About bi-amping the SDA.. Surely you meant that there isn't a way to bi-wire the SDA. As for bi-amping, the pannys handle the bi-amping logic internally. Yeah. I do think that most modern day receivers are common-ground but I guess I better watch for some smoke when I hook them up next week.

kchilaka wrote: »

I like your analogy Yup RX8 over a viper. About bi-amping the SDA.. Surely you meant that there isn't a way to bi-wire the SDA. As for bi-amping, the pannys handle the bi-amping logic internally. Yeah. I do think that most modern day receivers are common-ground but I guess I better watch for some smoke when I hook them up next week.

Ah... cool. I have to admit I'm pretty unfamiliar with the those amps. I have a Pioneer multi-channel amp, and it supports bi-amping but only by using the rear surround channels' speaker binding posts. So, on the Pio you can't bi-amp without also bi-wiring. Pretty sweet if the Panny's can just route the additional power though the one set of binding posts. I'm definitely going to have to take a closer look at those!

guess I know why it is echoey - one of the tweeters does not work, it is the one when NOT using SDA. I disconnected the IC, so will have to check out the other tweeter. I know about the tweeter upgrade, for now would just like to use the original so I am going to keep an eye peeled out for that