SDA 2 Crossover

ben62670

I am out of Ideas:(

Face

Here's something you could do with those SDA2 cabinets.
http://www.audiokarma.org/forums/showthread.php?t=180935&highlight=tannoy

SDA2Guy

Your link is invisible to me because I am not "a member". However, I suspect your post is in jest rather than anything of actual help.

How about it, Polk Community? Any more ideas?

I have begun to suspect this problem has existed since the purchase date. The lack of bass was not apparent due to the presence of the subwoofer in a 6.1 system (Lexicon CP-1, no center channel). On the few occasions I listened as two channel, my impression was they were light on bass.

What do you say, Polk Customer Service? Could this defective crossover still be covered by the 'defect in workmanship or materials' clause? Still got any parts on those shelves?

read-alot

The caps and resistors to swap out your "defective" ones are very inexpensive if you can operate a soldering iron.

SDA2Guy

How can you tell it's caps and resistors? It's already been stated that there is an inductor between the positive lead and the driver. I'd rather just have Polk Customer Service send me a new crossover to replace the one that was defective from day one.

ben62670

If you want you can send it to me, and I'll take a look at it, but I will be gone till Oct 12th. Any way you could come up? You could stay here. Big house with a lot of empty rooms.
Ben

SDA2Guy

Ben, I would love to come up, however I'm currently up to my eyeballs in work, which will not be changing any time soon. If I could really send you the crossover that would be great. Please let me know how to best extract it from the speaker cabinet.

ben62670

SDA2Guy wrote: »

Ben, I would love to come up, however I'm currently up to my eyeballs in work, which will not be changing any time soon. If I could really send you the crossover that would be great. Please let me know how to best extract it from the speaker cabinet.

I will send you contact info. I am going out of town till Oct 12th.
Ben

danger boy

SDA2Guy wrote: »

What do you say, Polk Customer Service? Could this defective crossover still be covered by the 'defect in workmanship or materials' clause? Still got any parts on those shelves?

Highly unlikely.. Call Ken at Polk customer service and he may have some ideas. WE're all out.

[Deleted User]

Hello,
I'm afraid we don't have any of those crossovers remaining. However, if you'll remove the crossover and send it to me I'll be happy to take it home and test it. If you want to do that, please send it to Polk Audio, 5601 Metro Drive, Baltimore, MD. 21215 attention: Ken.
Regards, Ken

BIZILL

http://cgi.ebay.com/POLK-SDA-II-CROSSOVER-SPEAKER-AUDIO_W0QQitemZ160288669720QQcmdZViewItem?hash=item160288669720&_trkparms=72%3A1208%7C39%3A1%7C66%3A2%7C65%3A12%7C240%3A1318&_trksid=p3286.c0.m14

SDA2Guy

I will carefully remove it and ship to the address you provided. Since the DIM array seems okay, I will send *only* the part directly behind the speaker terminals. Let me know soon if you need more than this.

[Deleted User]

Hello,
I would prefer the complete crossover, that way I can see the complete picture. I examine crossovers using a spectrum analyzer and pink noise generator.
Regards, Ken

SDA2Guy

Ken,

The crossover coil is bolted to the cabinet with a nut that cannot be removed due to globs of a black substance applied during manufacture. :mad: Is there some technique I need to know about? The lower unit with the speaker terminals came out rather easily. The upper unit has an Allen headed bolt on the outside screwed to what appears to be a 7/16th nut on the inside. Even after scaping away as much black stuff as I could it still would not budge, as if welded. If you can test it without the coil part I could simply cut the wires. Or, I could cut the bolt or break the coil plastic. Let me know.

Thanks, SDA2Guy

[Deleted User]

Hello,
The large inductor can be left in place. There should be two wires coming from the inductor to the main circuit board that have Faston connectors which will pull off of the terminals on the main circuit board.
Regards, Ken

SDA2Guy

Sadly, the wires from the large inductor are soldered to the circuit board. I will cut the wires and solder them back when you return it later. Provided I can find a box around here it will be on UPS by tomorrow afternoon.

SDA2Guy

UPS estimates delivery for next Monday, Oct. 13th. Until then, take care. Thanks again, Ken.

skrol

It is not likely that the inductor would go "Open" as it it relatively hefty wire compared the the current that it carries. It could possibly "Short" if the varnish insulation is compromised. This would likely only change the value of the inductor.

All that said, I would check the solder joints on the X-over. I recently found a couple bad solder joints in on of my RTA11TLs. Look at all the soldered connections to the X-over Circuit Board and parallel connected components. Give them a little wiggle as a small crack in a solder joint may be hard to see.
Stan

SDA2Guy

You may be right and I wish I would have checked for this more closely, however the xover is now on a UPS truck headed to Baltimore. I'm sure our expert customer service rep Ken will check out this as well as all other possibilities.

[Deleted User]

Hello,
I received the crossover today, I'll go over it as soon as I can clear off my work bench. Should be today or tomorrow.
Regards, Ken

SDA2Guy

Thanks, Ken.

I can't wait to hear these speakers again.

[Deleted User]

Hello,
I had the chance to examine your crossover last night. So far it seems fine, you have the older tweeter protection devices, which I can replace. The tweeter and driver for the "stereo" section checked out fine. The tweeter and driver for the "SDA" section seem fine. The bass driver is a very simple circuit, there's the 11.2mH inductor (which, unfortunately, you had to remove from the circuit) in series with the positive wire going to the bass driver. Then the ground of the bass driver is connected to the negative input binding post. I'll borrow a fairly high value inductor, connect it in series and check the connections. But, everything seems pretty good. I've read the message thread and you indicated that you measured the DC resisitance of the 11.2mH coil, correct?
Regards, Ken

SDA2Guy

Ken,

I had not yet measured the inductor all by itself but rather the path from the red binding post to the black (positive) wire of the bass driver. The reading was 2.1 ohm. I have just now measured the inductor itself and the reading is again 2.1 ohm. I don't know how to make the multimeter issue a reading in mH, I am using the resistance/continuity setting. Any hints on how to use the multimeter would help me, a first time user. It seems to be a capable device, with several settings including duty cycle, which reads out in Hz but without current the value is always 0.000. Given your finding that it's checking out 'good' so far, perhaps there is some 'cold' solder between the inductor and black wire.

[Deleted User]

Hello,
I was able to connect a different inductor to the two ends of the copper wires that were left, on the circuit board, when the inductor was removed. The output looked as it should, showing a low pass filter point that was higher than the original design. That was due to my inductor being a different value from what you have. I'll replace the two older style tweeter protection devices and heat up all of the solder connections and look at the outputs on the spectrum analyzer to double-check everything.
Your measurement of the DC resistance of the inductor seems about right. I don't believe you can directly measure inductance with your meter. Can you go over how you determined that the 6.5" bass driver was working okay? Also, describe the original set of circumstances that led you to suspect that speaker's bass driver wasn't working? Maybe if we backtrack we can figure out what is going on.
Also, do you want me to remove those short pieces of wire that are where the inductor would attach? That way all you would need to do is insert the inductor wires in the same circuit board holes and apply some solder.
Regards, Ken

SDA2Guy

Ken,

The little remaining stubs of wire from the inductor will be my only clue as to where to reconnect when I reassemble. Looking back, I did not make as detailed a diagram as I should have. But if you can leave two obvious holes there for me to see, then I'm okay with you removing the short pieces.

The speaker testing came about when Neptune Beach Dawg came over for a listen. With the grilles off and some bass-heavy material on CD it was clear the right channel woofer was working, visibly jumping out of the cabinet and very audible. The left channel woofer was still, lifeless, noiseless. After he left, I called customer service and asked how I could tell if the driver was bad. I was instructed to connect the speaker cable directly to the driver terminals at a low volume setting and listen. When I did this there was clear, clean music playing from the speaker. The conclusion was the x-over must be bad.

[Deleted User]

Hello,
I replaced the two older Polyswitches looked at all the solder connections and re-soldered any that were suspicious. I repeated the individual input versus output test and all's well with the stere/SDA outputs. I cleaned out the two 11.2uH holes and put two small paper dots on the underside of circuit board to help locate the connection. I'll send out the crossover today, re-install it in the speaker and we'll work from there.
Regards, Ken

[Deleted User]

Hello,
The crossover is on its way via FedEx, if you PM me I can give you the tracking number.
Regards, Ken

NotaSuv

WOW that is above and beyond the normal customer service one gets from most companies.....you guys are the cream of the crop.....

[Deleted User]

Hello SDA,
Freeman was able to determine that the magnet had shifted on your driver and he was unable to repair it. However, he did find an original MW6501 in his area so we're sending it out to you today.
Regards, Ken

skrol

Is this a common issue with these drivers? I saw where someone preemptively epoxied the magnet to the speaker basket. Is this something that we all should consider?
Thanks
Stan