Blown SDA-2B

TheRealSpinner

Dammit! Well, it sounds as though I've blown the mids on the new SDA-2Bs. I think the tweeter (same side) is blown also because when I play the test tones (setting volume levels for surround sound), the left speaker has significantly less treble, and I end up turning that side up to compensate.

I've tried to look up parts on PolkAudio before, but I can't seem to figure it out. Any suggestions on which replacements? I know I should replace both tweeters at the same time, but is that the same for all four mids? How much am I looking at spending?

smglbrth

You can check the schematics on the title page for the vintage SDA's in this "vintage speakers" section. However, it is my understanding that since Polk tended to "use what they had" sometimes it's best to pull the drivers to see exactly which ones they are. If you purchase all four you're looking at around $48/each, plus tax if your state requires it.

BTW - it stinks that you smoked 'em...

TheRealSpinner

Thanks. I hadn't even thought to look at the schematics page. I thought of that as how internals were wired as opposed to driver and parts also.

TheRealSpinner

After doing some more reading, I had assumed that my mids were blown based on the crackly sound they put out, but when I push on them, I don't feel anything. I also hear the distortion when I listen at low volumes.

Someone suggested (on another thread) that it might be the source rather than the speaker since it sounds that way at low volume as well as high volume.

Also, is there a way to tell which woofer is blown? Um, nevermind... When I push on the innermost speaker (left channel) it swueeks and whistles. Guess that's the blown speaker.

TheRealSpinner

So, is it worth replacing the speakers by the pair (as in left and right)? Vs. Only ordering one speaker?

Also, since I'm considering purchasing tweeters (I know to replace those as a pair which is why I ask about the mids), I was thinking of upgrading to the RDO-194 (as opposed to the 198s) since I don't feel like messing with the internals, but how do I know if the tweeters are blown. Would they sound crospy like blown woofers? My initial reason for thinking they were blown is because of the test tone for volume adjustment sounding less bright, but it was also suggested that that may be caused by a bad internal switch?

smglbrth

I'm sure someone who is much more knowledgeable than me can clue you into the troubleshooting aspect. I'm not that "into" troubleshooting SDA's. So, sorry can't help you much there...

PreCd

Let me ask you a question. You say the SDA2Bs are new to you. How long did you run them before the problem presented itself?

TheRealSpinner

Well, the story goes like this. I bought them used from some guy who probably bought them at a storage auction or something. They soynded good up close, in his tiny apartment. I bought them with the intention of using them at work.

I took them to the machine shop I work at and played them with my (undepowered) Onkyo receiver and they sounded like crap and distorted all over the place when I cranked the volume. So I decided to bring my JBLs from home, to the shop and vice versa.

With the SDAs at home and hooked up to my Maranz receiver, it started shutting down on me (due to the fact that the Marantz requires 8 ohm speakers.) So, I bought a used GFA 555 and hooked that up. Been listening to them like that (with a home-made ic cable-wire shoved into the pins and blades) for a few weeks now. The other day, I was playing some music and I got carried away and turned the volume up to about max for like a second. (Lots of distortion came out is the speakers), then played them at party levels for the rest of the evening. The next morning is when I noticed the crackling mids. :-(

As far as the tweeters, the first time I hooked the speakers up at home, I played test tones to set levels and noticed the left channel was less bright.

PreCd

As Paul Harvey used to say this is the rest of the story :biggrin:

Before you buy anything you need to check everything that you are able to check 1st. So grab a multimeter and set it to DC millivolts. Turn on your Adcom without anything connected. Let it warm up like this for 10 minutes or so. Observing the correct polarity check the voltage on the left channel then the right channel. Write those down and report back.

TheRealSpinner wrote: »

Well, the story goes like this. I bought them used from some guy who probably bought them at a storage auction or something. They soynded good up close, in his tiny apartment. I bought them with the intention of using them at work.

I took them to the machine shop I work at and played them with my (undepowered) Onkyo receiver and they sounded like crap and distorted all over the place when I cranked the volume. So I decided to bring my JBLs from home, to the shop and vice versa.

With the SDAs at home and hooked up to my Maranz receiver, it started shutting down on me (due to the fact that the Marantz requires 8 ohm speakers.) So, I bought a used GFA 555 and hooked that up. Been listening to them like that (with a home-made ic cable-wire shoved into the pins and blades) for a few weeks now. The other day, I was playing some music and I got carried away and turned the volume up to about max for like a second. (Lots of distortion came out is the speakers), then played them at party levels for the rest of the evening. The next morning is when I noticed the crackling mids. :-(

As far as the tweeters, the first time I hooked the speakers up at home, I played test tones to set levels and noticed the left channel was less bright.

TheRealSpinner

I did check the DC offset on Adcom when it arrived, and before I hooked it up. I got .023 Volts (23 mV) DC on the right channel, and -.057 Volts (-57 mV) on the left channel. I was told that this was acceptable (not fantastic, but since it was under 100, it was not going to damage anything). I haven't checked it since the speaker problem, but since the multi meter is at work, I'm assuming its still the same.

Schurkey

TheRealSpinner wrote: »

Been listening to them like that (with a home-made ic cable-wire shoved into the pins and blades) for a few weeks now.

Pin to pin, blade to blade? Or pin to blade, blade to pin?

TheRealSpinner

Pin to pin, blade to blade.

PreCd

Gotcha. I would not buy anything until I rechecked that. Chances are it is ok but you never know.

TheRealSpinner wrote: »

I did check the DC offset on Adcom when it arrived, and before I hooked it up. I got .023 Volts (23 mV) DC on the right channel, and -.057 Volts (-57 mV) on the left channel. I was told that this was acceptable (not fantastic, but since it was under 100, it was not going to damage anything). I haven't checked it since the speaker problem, but since the multi meter is at work, I'm assuming its still the same.

gimpod

TheRealSpinner wrote: »

with a home-made ic cable-wire shoved into the pins and blades

Only the pin connector should be used on those 2B's, The blade is to be used with the stock Polk AI-1 IC for non-common ground amps other wise it is not used if you do you are connecting the left and right grounds from the amp together through the speakers and this is a no no.

PreCd

If it were me I would bring my meter home and check all the drivers and tweeters. I have the proper readings in my notes that I can dig out and will post later.

PreCd

Ok. Here are the readings I recorded on my drivers and wiring to the drivers:

Left Channel

• MW6511 - 3.1 OHMS
• GR/BL LEAD TO MW6511 - 11.6 OHMS
• MW6503 - 6.9 OHMS
• BK/WH FROM MW6503 - 7.9 OHM

Right Channel

• ALL THE SAME AS LEFT CHANNEL

This will at least tell you if your drivers have a connection from end to end and are reading proper resistance. Now I do have my 2Bs TL'd so the wiring may read a little different. Let us know.

TheRealSpinner

I can only assume that you noted resistance with each driver disconnected. Also, my speakers only have 2 mids, a tweet, and a passive (which shouldn't have speaker leads or resistance, right).

Oh, Nevermind, I get it. Pull the wires off the MW6511. It should measure 3.1 ohms, and the green/black wires that were pulled off measure 11.6 ohms. Etc.

What will this tell me, though? Won't blown speakers still read the same as good speakers?

PreCd

You have it. The one reading is for the leads disconnected to the driver and the other on the ends of the wire headed down to your xovers.

If you opened the winding on the driver then you will be able to see this when using the multimeter. If you see a large different holler back.

You can also give the drivers a visual inspection to see if the spider is torn. Also I missed the post above where you mentioned the driver makes a noise with no music source playing and you gently press in on the driver. That ain't good you are right.

TheRealSpinner wrote: »

I can only assume that you noted resistance with each driver disconnected. Also, my speakers only have 2 mids, a tweet, and a passive (which shouldn't have speaker leads or resistance, right).

Oh, Nevermind, I get it. Pull the wires off the MW6511. It should measure 3.1 ohms, and the green/black wires that were pulled off measure 11.6 ohms. Etc.

What will this tell me, though? Won't blown speakers still read the same as good speakers?

F1nut

gimpod wrote: »

Only the pin connector should be used on those 2B's, The blade is to be used with the stock Polk AI-1 IC for non-common ground amps other wise it is not used if you do you are connecting the left and right grounds from the amp together through the speakers and this is a no no.

Bingo!

Better have that amp checked over by a professional too.

TheRealSpinner

You think I might have damaged the amp with the speakers because I had the blade to blade wire hooked up? Or do you think that because my speakers got damaged, my amp might be the culprit?

Any suggestions as to where in San Diego I might have my equipment checked out? It's one of those things, I've got a multi-meter and soldering iron, but in order for me to check anything out, I'd be asking a LOT of specifics.

Thanks

TheRealSpinner

The results are in. I measured resistances, and here is what I found:

Left speaker
6503 6.8 ohm
Black/white 8.1 ohm

6511 3.3 ohm
Green/brown 11.7 ohm

SL2000 6.0 ohm
Black/white 0.9 ohm

Right
6503 6.8 ohm
Black/white 8.1 ohm

6511 3.2 ohm
Green/brown 11.6 ohm

SL2000 6.0 ohm
Black/white 0.8 ohm


DC offset on the left channel of amp was 58 mV
DC offset on the right channel of amp was 24 mV

TheRealSpinner

I only felt one blown mid: left side 6503
I'll ask again, should I replace the right channel at the same time? Or just the one side?

Also, what about the tweeters, how do you know if they are blown? Might I just replace them with RTO 194's while I'm at it?

F1nut

^ A perfect example of why posting while drunk is never a good idea. ^

F1nut

TheRealSpinner wrote: »

You think I might have damaged the amp with the speakers because I had the blade to blade wire hooked up?

That is a possibility.

Do you another amp you could try?

F1nut

TheRealSpinner wrote: »

I only felt one blown mid: left side 6503
I'll ask again, should I replace the right channel at the same time? Or just the one side?

Start with the one.

Also, what about the tweeters, how do you know if they are blown? Might I just replace them with RTO 194's while I'm at it?

You said you've got no highs in the one channel, so chances are it's the tweeter. The proper part number is RD0194-1.

drumminman

Smallies wrote: »

Never really found voltmeter useful in my dealings with multiple SDA 2's off the used market. Just ended up with several drivers with a good reading number written on the back along with the black question mark and not working. These aren't good crazy maniac speakers. They will stress your amp with low ohms and tease you with good sound to turn it up loud. People say these are 500 watts and there's no way.My AR9LSI's are rated 400 and they can take more power than the albeit almighty tiny 6 inch Polk drivers flopping around for their life. Good for you might be the replacement tweeters and mw-03 that ship from so-Cal for $48 each. I say forget the whole thing and buy some glorious Polk monitors and be done. SDA effect is stupid.

:rolleyes: I wonder if you've ever heard a properly set up pair?

TheRealSpinner

Thanks. I'm in the process of ordering one new mid. I'm trying to get an answer as to how I can pick them up from their location in Vista (about 45 minutes from me). While I'm at it, I might as well get some RDO 194s. At least I'm saving on shipping (in lieu of gas, I guess). :rolleyes:

F1nut

You can't pick them up, it's not a retail location. Besides shipping is free for CP members.

TheRealSpinner

Oh, I thought I heard of somebody picking their speakers up at the warehouse. Oh well, I guess I'll just order them. I guess I call to order?

TheRealSpinner

...and they're closed for the day. :sad:

TheRealSpinner

So, can a woofer be blown and not feel crispy when I push on it? I'm thinking of the other woofers and to replace them or not. The SDAs sound so crappy now, I'm finding it hard to believe that it is only due to the ONE blown speaker.