sda1c's tweeters ?

mesquitehead · April 2004

I am running my sda 1c's through an hk pre to a Parasound hca2205 amp and the tweeters cut out at what I consider moderate volume . I have good cables and all proper connects. My question is ...is there a tweeter upgrade for my old friends? I have had them in storage for a couple of years and pulled them out last week after purchasing the new Parasound....which kicks some serious posterior.....hell I even went out and picked up a sacd player to the dismay of my wife. any help would be appreciated.

F1nut · April 2004

It is possible that the safety guard (thermal overload switch) for the tweeters has gone bad. Contact Ken Swauger at Polk cusotmer service about getting some new ones. Also, since you asked about tweeter upgrades, Polk has a new replacement tweeter for the SL2000's that is getting rave reviews around here.

HBombToo · April 2004

Originally posted by F1nut
It is possible that the safety guard (thermal overload switch) for the tweeters has gone bad. Contact Ken Swauger at Polk cusotmer service about getting some new ones. Also, since you asked about tweeter upgrades, Polk has a new replacement tweeter for the SL2000's that is getting rave reviews around here.

I thought this very same thing last night when my inet connection died and I just gave up. On the Polk crossover schematics they call this device a polyswitch and in many cases they can just be removed.

HBomb

dorokusai · April 2004

I wouldn't recommend removing them. Contact Ken Swauger about the upgraded Polyswitch(Safety Guard), as suggested by F1Nut.

kswauger@polkaudio.com

BobMcG · May 2004

I expect you've resolved this problem by now through Ken but if not and for future others:

F1 and doro are spot on. It's a PROTECTION circuit. Don't bypass it! Polk has sent me replacements for free... which is cheaper than buying new tweeters.

It is the little thermal sensitve semi-conductor that is breaking the circuit to your tweeter. With the stock unit used on a lot of the older SDA's once they were tripped for the first time, they usually got easier and easier to set off. Trigger happy you might say. The replacement conductors I've replaced in the past (thanks to Ken) have been larger ones that have never been a problem. If you're handy with a soldering iron the job isn't difficult.

mesquitehead · May 2004

Thanks to Ken and you guys the problem is solved...you guys were right, I soldered in the new parts and they work like new.

Larry Chanin · June 2004

Hi Guys,

mesquitehead, glad to hear that things worked out OK for you.

I'm in the process of putting together a new home theater and after about 10 months of being in storage I've finally gotten my all my Polks out of mothballs and set them up. Aaaah.

Well, I've only had them up and running a few days, and I ran into a problem on one of my SDA-1Cs which may be the attributable to the protective device. I did run some test sweeps on the speakers that didn't sound very loud and played a few movies at moderate listening levels. It was only when I was listening to a music DVD did I noticed what appeared to be a balance problem with the sound not centered. After investigation I realized that I was getting almost no sound from my left speaker.

About a year ago I had a similar problem on my right speaker after running test signals, but the speaker mysteriously returned to service in an hour or so. So far the left speaker is still out of service after a day.

I've sent an email to Ken, but I was wondering in the interim whether it would make sense to temporarily place a jumper across the safety guard just to see if my speaker returns to service? In this way I'd be in a better position to know definitively what the problem is.

If this makes sense I'd like your advice on how to do this. I've never "popped the hood" on my SDAs, so I'd appreciate a little tutorial. Exactly what do I do to gain access to the crossover circuit? Would it be best to leave the speakers in the upright position? Any other advice would be greatly appreciated.

Thanks.

Larry

DarqueKnight · June 2004

Larry,

If you look at the rear of the 1C, you will see a hex head bolt just below the binding post plate, this is the retaining bolt for the crossover circuit board.

Here's the procedure:

1. The crossover circuit board is easily accessed by removing the passive radiator. The passive radiator is secured by eight wood screws. The passive radiator does not fit snug against the baffle board and will simply fall out when the last screw is removed. Therefore, the top screws should be removed last and the passive radiator should be held in place with one hand while the last screw is being removed.

When replacing the passive radiator, take care not to overtighten the screws. The threads in the MDF are easily stripped out.

2. After removal of the passive radiator, the crossover circuit board will be seen near the bottom rear of the cabinet. Detach the three wiring harnesses. You cannot get them mixed up because they are all different sizes.

3. Remove the crossover circuit board from the cabinet by removing the hex head retaining bolt with 5/32" or 4 mm hex wrench. Be sure to support the board with one hand while you are removing the retaining bolt.

4. The protector switch is the disk-shaped device right next to the smallest wiring harness recepticle. That recepticle is labeled "INPUT" on the circuit board. The protector switch is labeled "S1".

5. The protector switch is near the edge of the circuit board and it is very easy to solder a jumper wire across the terminals of the switch.

PolkWannabie · June 2004

Originally posted by raife1
it is very easy to solder a jumper wire across the terminals of the switch.

But is this really advisable ?

F1nut · June 2004

Larry,

To gain access to the crossover remove the PR, the crossover will be mounted to the back wall. There is a bolt on the outside back of the speaker, remove that and the crossover comes off. All the wires are connected by those snap on jobs, so it's fairly idiot proof. The poly switch should be easy to find, it's a small yellow colored device labeled S1. I see no problem running a temporary jumper. If you'd like I can email you a schematic. You can work on it either standing, on it's side or on it's back, but you'll need to have access to the back if you lay it down....like on sawhorses.

Just a thought, before you pull out the crossover, check for loose connections on the board.

Jesse

EDIT: I see Raife beat me to the punch.....good job!

DarqueKnight · June 2004

PW,

It is certainly advisable as a diagnostic procedure:

Originally posted by Larry Chanin
I've sent an email to Ken, but I was wondering in the interim whether it would make sense to temporarily place a jumper across the safety guard just to see if my speaker returns to service? In this way I'd be in a better position to know definitively what the problem is.

With regard to permanently removing the device, I have been running my SDAs without the protection device for many years. However, if you play your music really loud and/or use low powered amplifiers, I definitely DO NOT recommend removing the tweeter protection device.

I removed the protection switch because it caused a small but noticeable loss of high frequency detail. The newer polyswitch may not have an adverse affect on sound quality. I am not aware of any comparisons of sound quality between the old and the new polyswitch. Ken Swauger in Polk Customer Service may have some information on the performance of the new switch.

[Deleted User] · June 2004

Hello,
Just email me at kswauger@polkaudio.com with your address and the model speaker and I'll send out the Polyswitches, at no charge along with a brief set of instructions.
Regards, Ken

trubluluc · June 2004

As I just purchased a pair of SDA 1C's.

Question:
Do the newer tweeters (SL2000T)
come with the better polyswitches already in place?
Or would I have to replace the whole crossover to avoid having to do any soldering?

thanks,

-Luc

I-SIG · June 2004

Luc,

I'm like 90% sure the poly-switch dooflotchie is located on the crossover and not as part of the tweets. Sorry.

Wes

trubluluc · June 2004

figures:) good thing I got the speakers pretty cheap, I may have to put some $
into them.

thanks Wes!

-Luc

Larry Chanin · June 2004

Hi Guys,

Is my face red!!:o

When Ken responded to my email he suggested that I check my amplifier. Since I said I was getting almost no sound from my speaker, he knew that the protective circuit would only have effected the tweeters.

When I checked, I found that my output connector from my pre/pro to my amp was loose. DUH!!:rolleyes:

Rick:

I appreciate your concern about bypassing the protection. What I was planning to do was use alligator clips to temporarily jumper the protection to see if operation of the speaker would be restored. If so, I would replace the device, otherwise I might have had a more serious problem.

Well, other than embarassing myself, I'm still glad I asked for advice, because this thread is loaded with great step-by-step instructions and tips. Thanks Raife and Jesse.

I was thinking that way down the road when my theater is finished I might get to use these instructions. The last thing I plan on doing is to perform multi-channel equalization on all my speakers. Based on Raife's comments regarding the safety guard's affect on high frequency response, I might jumper the device and run a frequency response curve before and after. If it looks significant, I might change them out to the new replacements.

Thanks again for taking the time. And by the way, my wife thanks you as well. She says its remarkable how my mood directly correlates to the level of performance of my system.

Regards,

Larry

sda1c's tweeters ?

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