Polk SDA 2 Project
puunda
Posts: 123
Hi everyone,
Has been many years since I've owned a pair of vintage Polks. I have recently bought a pair of SDA2 which is in very good condition other than the tweeters not working.
Cabinet, grills, drivers, SDA cable all look in excellent condition. I plan to replace the tweeters with the newer ones, and maybe even do some of the upgrades.
I do have 2 questions ... well 1 question and a request.
1.
I am confident they are the original SDA2 based on the driver configuration. However according to the SDA handbook, the says this speaker should have an external fuse on the back, however my speaker doesn't have the external fuse. Am I correct in thinking that this is an SDA2 even without the external fuse?
2.
Do Polk still sell the replacement RDO tweeters? If so would anyone on here be able to buy them and ship them to me in Australia? I'll pay for it of course. Just you can't get them here.
TIA
Has been many years since I've owned a pair of vintage Polks. I have recently bought a pair of SDA2 which is in very good condition other than the tweeters not working.
Cabinet, grills, drivers, SDA cable all look in excellent condition. I plan to replace the tweeters with the newer ones, and maybe even do some of the upgrades.
I do have 2 questions ... well 1 question and a request.
1.
I am confident they are the original SDA2 based on the driver configuration. However according to the SDA handbook, the says this speaker should have an external fuse on the back, however my speaker doesn't have the external fuse. Am I correct in thinking that this is an SDA2 even without the external fuse?
2.
Do Polk still sell the replacement RDO tweeters? If so would anyone on here be able to buy them and ship them to me in Australia? I'll pay for it of course. Just you can't get them here.
TIA
Comments
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Post a photo of the front and one of the binding post area.
Surely there is a Polk distributor in Australia.
Here you go.
https://au.polkaudio.com/contact-usPolitical Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Sorry I thought I had attached phots. I tried to edit the original post to add photos, but can't.
As far as Polk/Sound United here, there is an office. However many years ago I tried to order the replacement SL3000 / RDO drivers and they said they were not available in. Things many have changed. I will try them again.
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There will be a polyswitch on the crossover board, which takes the place of the fuse. The polyswitch is a resettable thermal device. It's common practice to remove the poly and replace with a .5 ohm resistor.
It's also common to disconnect the SDA tweeter as it imparts a phasey effect.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
There will be a polyswitch on the crossover board, which takes the place of the fuse. The polyswitch is a resettable thermal device. It's common practice to remove the poly and replace with a .5 ohm resistor.
It's also common to disconnect the SDA tweeter as it imparts a phasey effect.
So this is a confirmed SDA2? Did some SDA2 come with a fuse and some come with a polyswitch?
I will check the drivers hopefully this weekend and see if it's the tweeters or XO which is the problem.
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The SDA II (not 2) only came with polyswitches.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
There will be a polyswitch on the crossover board, which takes the place of the fuse. The polyswitch is a resettable thermal device. It's common practice to remove the poly and replace with a .5 ohm resistor.
It's also common to disconnect the SDA tweeter as it imparts a phasey effect.
So this is a confirmed SDA2? Did some SDA2 come with a fuse and some come with a polyswitch?
I will check the drivers hopefully this weekend and see if it's the tweeters or XO which is the problem.
Yes. Confirmed.
The very early ones had a fuse and when they deleted it and went to the polyswitch they changed the resistor from 4.0 Ohm to 3.5 Ohm to compensate for the extra resistance of the polyswitch.Post edited by Gardenstater onGeorge / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
A few updates on this project.
I contacted Sound United / Masimo here in Australia, twice and got no reply. I used the contact form, then I emailed their service department directly, and no reply to either. Based on my previous experience, the won't have the replacement tweeters, and even if they did, it would be prohibitively expensive.
So I removed the drivers and measured them. 1 of the tweeters was open circuit. Got that repaired by a local repairer and hooked it all up today.
It sounds ok, but it seems there is only sound from 1 tweeter on both the speakers. Only the tweeters on the inside work, the ones on the outside have no sound.
I checked the SDA cable and it measures fine.
Based on previously comments, I'm thinking the tweeters got disconnected. I will check the XO next -
You don't want the SDA tweeters working anyway as they impart a phasey effect.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
You don't want the SDA tweeters working anyway as they impart a phasey effect.
So you're saying leave it as it is? Have only 1 tweeter on each speaker working?
I've not checked the SDA woofer yet. Is there an easy way to do that? -
That's what I'm saying.
To determine if the dimensional driver is working listen to the speakers with the SDA cable disconnected, then listen with it connected. The difference should be
obvious.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
That's what I'm saying.
To determine if the dimensional driver is working listen to the speakers with the SDA cable disconnected, then listen with it connected. The difference should be
obvious.
Correct, on that model the dimensional driver will NOT work without the cable connected. You may hear some sound from the back wave of the active drivers playing coming through BUT once you connect the cable you should notice a huge difference just by touching the driver with the cable engaged and disengaged. -
I suspect the SDA tweeter and woofer are not working. I've taken the SDA XO out and it appears to be ok - as in the cabling is all connected the components appear to be ok. The polyswitch measures ok too.
So the drivers are ok and the XO is ok and the connection is ok. I'm guessing the SDA signal comes in from the other speaker? So that is where I'll check next -
Crossover connections are OK you say. Did you check at the dimensional tweeter end to see if it is disconnected? Someone could have just removed the negative quick connect and it wouldn't play then.
There should be resistance checks that can be done in the SDA Handbook, as well as the procedure to check out the SDA function.
George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Everything measured ok and appeared to be working ok, so I could never figure out what's going on.
Turned out to be a loose connection. The Pin-Pin cable doesn't fit snugly in the socket sometimes and you need to jiggle it. Once jiggled, it's working perfectly -
Blade/blade, not pin/pin.
Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Why[ibJimmymac1965[/i] -
Jimmymac1965 wrote: »
Read the thread Jimmy, your answer is in it! -
Stupid question Jesse…
Why does the sda tweeter, on the sda II’s, cause a phase effect and no phase effect on my sda SRS’s?
Curious….. -
skipshot12 wrote: »Stupid question Jesse…
Why does the sda tweeter, on the sda II’s, cause a phase effect and no phase effect on my sda SRS’s?
Curious…..
Because your model does not have a dimensional tweeter.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Oh, I did not know that… thanks.
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SDA1c, SRS2, SRS2.3 & 2.3tl, SRS, SRS1.2 & 1.2tl all use a progressive point source tweeter arrangement.
