Polk SDA SRS 3.1TL burnt choke coil on crossover board

Nibs

Hey Guys! I have a pair of SDA SRS 3.1TLs. I hooked them up to a Hafler DH 500. I took them up to power and the tweeters began to smoke. They were replaced with new production Polk tweeters for that model. After they were replaced the speakers sound muddy and muffled. The sound just is not right. I opened them up to inspect the board/crossover and found one of the coils of copper wire burned in the middle of the coil and the zip tie melted off. That coil needs to be replaced, but I don't know what part it is. Can anyone confirm if this is my only problem? What is the part number to that coil, and where can I find a replacement? Thank you all very much for your help!

stogie

I think this is the coil: Jantzen part 000-1452 0.30mH 22awg. Parts express can special order it for you- takes about 6 weeks.

http://www.jantzen-audio.com/wp-content/uploads/2013/04/Air-Core-Wire-Coils-List-12-08-2015.pdf

here is the schematic

https://us.v-cdn.net/5021930/uploads/attachments/1/8/5/1/1/26697.pdf

pitdogg2

Is that amp common ground? Seems to me those just don't toast for no reason

tonyb

That amp was available in kit form too, hope somebody knew what they were doing. Also hope you didn't have it in bridge mode. After replacing the necessary parts, I'd get that amp checked out.

Toolfan66

The traces on the board could be fried as well..

F1nut

You'll likely need to replace the resistor as well. In fact, might as well upgrade all the caps and get Gimpod's boards.

Either the amp isn't common ground or has a serious issue.

Nibs

Thanks, Guys! That helps. I am unaware of how the amp was grounded. It had some odd box attached to the back of it that was supposed to be some sort of secure power cut off. That box was maybe 4" x 5". It was not bridged. After it fried my speakers I sent the amp down the road. I'm currently looking at the Crown XLS 1500 to go with a Sony STR-DA90ESG I just purchased.

stogie.... How can you be sure of that part number? I called Polk today, but it was too late. I will try them again on Monday to confirm. Thanks for the links, stogie!

I'm not up to speed with electronics, but I have a guy who spent most of his career inspecting circuit boards. He is going to help me bring these back to life.

Thank you very much for the input!

F1nut

For an amp, keep looking.

Toolfan66

F1nut wrote: »

For an amp, keep looking.

^^^^^This....

F1nut

stogie.... How can you be sure of that part number?

That is the correct replacement inductor. The schematic gives you the value and gauge. Polk does not sell a replacement.

daddyjt

You need to find out WHY that inductor fried - Those types of parts don't typically fail for no reason. A good guess would be high DC offset from the amp, but unless you're sure, you risk the same failure again, possibly taking additional components the next time. Check the board for cracked traces or shorts. Also check all your drivers and tweeters, to ensure no shorts there either....

Nibs

What are Tracers? What do I upgrade the caps to, and what is a Gimpod board? Is that a whole new circuit board?

stogie

As F1 stated, Polk does not sell inductors. Parts Express can special order the inductor from Janzten.

daddyjt

Nibs wrote: »

What are Tracers? What do I upgrade the caps to, and what is a Gimpod board? Is that a whole new circuit board?

Traces are the thin metal pathways on a circuit board that connect the various components together. If one cracks, that electrical connection will be severed, or at best intermittent....

I think the Gimpod upgrades are available by emailing Vr3Mods@GMail.com

drumminman

What everyone is suggesting is to order new circuit boards, named for their producer, Gimpod. Once they arrive, populate them with new capacitors (Sonicap brand available at soniccraft.com/ or Clarity Caps), new resistors such as Mills 12 watt, and new inductors such as the Jantzen already mentioned. VR3 mentioned above may have the inductors you need.

You'll need to know how to solder. If you don't you can find tutorials on You Tube.

Do one board at a time so if you get confused you can use the untouched one for reference.

Nibs

I will do more research and get my parts list together. Thank you for the education, Gentlemen!

Nibs

When you say to upgrade the Caps, are you referring to Caps with a different value, or just NEW Caps?

F1nut wrote: »
For an amp, keep looking.

What are you referring to? Stay away from the Crown, or just get rid of the Hafler (which I already have).

So just start from scratch and build new boards? I will do more research and get my parts list together. Thank you for the education, Gentlemen!

Nibs

F1nut wrote: »

stogie.... How can you be sure of that part number?

That is the correct replacement inductor. The schematic gives you the value and gauge. Polk does not sell a replacement.

Thanks, F1, but I don't know how to read the schematic......

tonyb

Nibs wrote: »

F1nut wrote: »

stogie.... How can you be sure of that part number?

That is the correct replacement inductor. The schematic gives you the value and gauge. Polk does not sell a replacement.

Thanks, F1, but I don't know how to read the schematic......

Then you might be better off letting someone else do it....though it may cost you some coin, it would be in your best interest to have it done right. If the whole board needs to be replaced you might as well do both, each speaker, as one might sound different than the other should you elect to only do one.

daddyjt

Pretty sure he's saying to steer clear of Crown amps. Most of them are a "class D" amplifier, which gives them great power in a small chassis with very little heat generation. The problem is, the accomplish this by modulating the incoming signal, which creates artifacts in the reproduced sound. These artifacts are not detectable at low frequencies, which is why class D amps are common in subwoofers. They are not suitable for full range home audio though.

pitdogg2

daddyjt wrote: »

These artifacts are not detectable at low frequencies, which is why class D amps are common in subwoofers. They are not suitable for full range home audio though.

pretty bold statement as some of the best now use them for much more than sub amps. What F1 is stating is there are better amps for about the same coin that would be a better fit. IF LOUD is all you're after then by all means go for it, But if excellent articulation of the music with a wonderful sound stage with depth and width then you need to keep looking. There have been some excellent amps for sale here so keep posting and get your learn on. For most on here to be able to buy and sell you'll need 100 post. There might be a seller here who would sell you something, but that is their call. the 100 post rule was for to help keep people from getting took as we would be better acquainted with you if you post and stick around.

daddyjt

No offense intended Pitdogg. Here's a better explanation of why class D is not the best choice for home audio:

Class "D", or "Plate" amps are not typically going to be your first choice for driving anything other than subs or pro audio applications. The reason for this, is that they do not use a linear amplification circuit. When your input source is sent to a class D amplifier, the first step is for the signal to be "modulated" into a series of "pulses" that the amplifier can apply gain to. To avoid hearing the nulls where the amplification circuit is switching on and off, the switching frequency is usually about 4 times the highest output frequency. So in the case of a full range class D amplifier, that frequency would be 80k Hz (20k Hz x 4). However, this high frequency switching creates severe EMI interference, which must be filtered off at the final output stage, with a low-pass filter.

While class D amplifiers are extremely efficient, and relatively in-expensive to produce, there are significant trade-offs. There is a lot of modification to your original input signal (The modulation and low pass filter). They make ideal sub amps, because the highest output frequency required is usually around 200 Hz, which gives a switching frequency of only 800 Hz, which does not produce the troublesome EMI interference. Also in pro audio applications, the sound quality expectations are not such that they would outweigh the cost/size/efficiency benefits of the class D design.

Nibs

tonyb: I have a guy who has spent most of his career working on circuit boards. He is my go to guy at this point. He is going to help me get this squared away. I would never attempt it, as I'm not a big fan of wasting my time and money. All that would do is just frustrate me further since I already messed these speakers up with a bad amp.

daddyjt and pitdogg2: Thanks for the input on the Crowns. The Crown Class Ds did get me excited just due to their size, weight, output and costs. The output specs on the XLS series are very enticing. Although, I would prefer to stay with something that is going to bring out he sound staging and quality as the music was recorded to produce. The older Crown amps are not Class Ds though, are they? What would be some better recommendations than the Crown XLS 1500? Adcom, Nad, Hafler DH 220?

I recently picked up a Sony STR-DA90ESG for some cleaner power than my cheaper Sony, and it has the pre-outs that I wanted for an amp. I also have my Marantz 2230.

F1nut

When you say to upgrade the Caps, are you referring to Caps with a different value, or just NEW Caps?

Replace all the caps and resistors with new. For caps, go with poly such as Sonicap. For resistors go with non-inductive wire wound such as Mills. Replacing all the inductors is an option. Whatever you do to one crossover you have to do to the other because they will sound different othgerwise.

So just start from scratch and build new boards?

Yes, Gimpod's boards allow for easy placement of new caps, which will be considerably larger than the originals and they are of much better quality.

What are you referring to? Stay away from the Crown, or just get rid of the Hafler (which I already have).

I meant avoid pro amps in general. They have a place and it's not in your home.

That Marantz would sound good.

tonyb

Nibs wrote: »

tonyb: I have a guy who has spent most of his career working on circuit boards. He is my go to guy at this point. He is going to help me get this squared away. I would never attempt it, as I'm not a big fan of wasting my time and money. All that would do is just frustrate me further since I already messed these speakers up with a bad amp.

Cool man, as long as you trust him, rock on and get it done. Do both speakers though, I know it will cost more money but really it's the only way to go. Darn hobby sucks us dry sometimes.

xjghost

This is not mine but was pointed out to me and would be a good amp for those speakers.... http://forum.polkaudio.com/discussion/169163/parasound-hca-1500a-power-amp-205-watts#latest Good Price too!

Nibs

I thought my original Hafler 500 was the ticket for these. I've used those amps for years, but the one I picked up just didn't work.

xjghost wrote: »

This is not mine but was pointed out to me and would be a good amp for those speakers.... http://forum.polkaudio.com/discussion/169163/parasound-hca-1500a-power-amp-205-watts#latest Good Price too!

xjghost: Thanks for the link. The specs on that look great! Being a THX amp I am not sure of the sound staging. I thought that was more for surround than stereo. Any other thoughts out there, guys?

Nibs

My Marantz is nice, but it only puts out 30W x 2. I want more power for my SDAs, Monitor 10, Monitor 5jr, JBLs, etc..... I found a 4300 for $400 at St. Vincent DePauls, but I passed on it. It needed to be cleaned up, and I wasn't sure what that would take. I know a guy here in town who is a pro with those, but he turned me off of it. He asked, "Do you need a quad receiver?". WTH? Do you want to work on it and make some money, or not? It came with the original cabinet, but some bozo put packaging tape on it. Refinishing any furniture lessens its value, but it would have been nice to do to clean it up. Another guy picked it up for $360 and sold it on Ebay for $700 as is.

Copy that! I would definitely do the same mods to each board. Balance is a wonderful thing. I called Polk and they actually have a few of those inductors lying around. They are going to send me two complimentary to replace my burned out ones. I could just replace those and be done, but building new boards sounds a bit more fulfilling!

xjghost wrote: »

This is not mine but was pointed out to me and would be a good amp for those speakers.... http://forum.polkaudio.com/discussion/169163/parasound-hca-1500a-power-amp-205-watts#latest Good Price too!

xjghost, thanks for the link! That has some great specs. My only concern is that it is a newer THX amp. How will it perform with staging and imaging in stereo? Any other thoughts on that, guys?

motorhead43026

That Parasound amp will drive those SDA's and never ever break a sweat. Parasound is a great match for vintage Polk speakers. A lot of us have them or have had them. This is a great amp and the sound quality is excellent as well as the price. I am really considering it for my stash. I bought a brand new Parasound a couple months ago for use on my SDA-2B's.

xjghost

I've got a Hafler 500 myself and it does very well. I also have an Adcom GFA 555II on them right now. It's a great amp too. Unfortunately the Parasound 1200II I bought to try out was damaged in shipping to me and my money is tied up at the USPO right now or I'd be all over that amp. have a Parasound HCA-800 on my Monitor 10's and love it. Which is why I pulled the trigger on the 1200II.

F1nut

Refinishing any furniture lessens its value

False.