Help fininding replacement part for speaker crossover

Trying to identify the blue component in the picture to find a replacement.

Something like this?


However, I take it you are aware that they aren't absolutely needed (and most speakers don't have them), if they have blown you could simply short them out, temporarily if you like, to prove everything works OK.

But it might be an idea to find out why you blew them first?.

Hey, thanks for the reply and yeah that looks like the part. I get some intermittent crackling or pops but not very often. It happens with multiple sources, tried different cables such as toslink and rca. Happens with 2 different receivers and now an amplifier 2 of which are brand new. So I'm sure it's the speakers themselves. I have already replaced the capacitors with new Audio grade dayton mkp 250v 3.3uf capacitors and still same issue is occurring. I have replacement 7W1RJ resistors for the crossovers but have not replaced them yet so once I get these thermistors and some new interna speaker wire I will have replaced the cheaper parts and hopefully have resolved the issue.

The speakers are about 20 years old I know that is not that old for speakers but just trying to save money if I can. I don't have the equipment to test these components and they are cheap either way, I know you said they are not necessary but can they be replaced with higher quality ones? The link you posted seems to have similar values so I'm guessing they would work? Please keep in mind I have only looked into this stuff for a couple of weeks lol I'm a newbie.

You are likely overdriving the speaker and the thermistor is cutting out (as it should). It is there to protect the voice coil. Modern amplifiers are way stronger than the 25W, 35W systems many of these speakers were designed to handle. Back in the day, most of the audio people I know wouldn't play their systems above 50% volume because of distortion and risk of damaging speakers - even though speakers were rated at the same rms wattage as the stereo. The problem, in theory, that distorted (non-sine wave) signals can go well beyond rated rms power.

gophert said:

You are likely overdriving the speaker and the thermistor is cutting out (as it should). It is there to protect the voice coil. Modern amplifiers are way stronger than the 25W, 35W systems many of these speakers were designed to handle. Back in the day, most of the audio people I know wouldn't play their systems above 50% volume because of distortion and risk of damaging speakers - even though speakers were rated at the same rms wattage as the stereo. The problem, in theory, that distorted (non-sine wave) signals can go well beyond rated rms power.

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Going back a GREAT many years I repaired some speakers for a local doctor, Dr. Holden (I can still remember his name, even though it's 40+ years ago).

The speakers were expensive Bowers & Wilkins (B&W), and back then (before they started making their own drivers) these ones used EMI 13x8 bass units. As I recall he had a Leak or Wharfdale amplifier (I didn't have to mend that) rated at a conservative 35W, and the speakers were only rated at 15W or so.

Unfortunately he went on holiday, and his teenage son had a party - I think you can see where this is going

So I had them for repair, both bass units killed, and I contacted Wilslow Audio (who were, and still are, a UK speaker specialist) to be told the 13x8's were no longer available - and what you had to do was cut the cabinets out and replace them with EMI 14x9's, which also had the benefit of higher power handling. So I cut the cabinets, fitted the drivers, sounded great again.

So exactly like you said, it worked perfectly fine - while been used 'properly' by the owner, but not when been abused by his son (and friends) at a party.

My issue with the OP's problem is how loud is he driving these speakers? - and is he really overdriving the amp enough to generate so much distortion that the 'fuses' trip out?. It's difficult with out seeing and hearing the problem, but i would associate pops and crackles more with the bass units than the tweeters?.

Running the amp at less than 1/3 of the volume, speakers are 180w 6ohm 20hz 20khz, they are budget though and I cannot find further specs but it is the dbdynamics Polaris II AC688F. The issue rarely occurs also like I may get one strange pop during a whole movie or some distortion after listening to music for 5 hours. I bought the speakers 2nd hand and they have had a rough life, even the cabinet on one had separated on one side and I pva glued it back.

I should of mentioned also the amp is rated at 85w rms per channel and there is a switch at the back to set the impedance which is set out of the box to 6ohms. The amp is a new Yamaha as-501b. The same issue was happening with a old receiver I got with the speakers and that receiver had all of the bass offloaded to the active subwoofer I got with it also which I don't really want to use. If Nigel is right and the drivers are damaged by the previous owner which is why they probably sold them and why they are not responding to me on FB marketplace now (buyer beware) then I'm going to replace them altogether because they use 8" truncated drivers which are harder to find, found some but in the states and they were average quality. So basically I'm starting with all of the cheaper components first to see if they are salvageable and learning something on the way so it is not a complete waste of $150 I spent on the speakers and old receiver. Doing what I can guys without spending too much and I have a new soldering iron, rosin core solder and a PCB holder/clamp ready to use.

I'm a 39yo guy so I don't crank it or anything I just set the volume to constantly be at 1/3 and control the volume through my PC and just have it connected atm with toslink. If I cranked it my wife would kill me lol.

I doubt this component would be causing your issue but If you want to test it then try removing it and see if the problem(s) your experiencing gets better, worse or the same.

Also the truncated drivers I found are 8ohms so I'm guessing I would have to replace the tweeters and crossovers also and by that stage I may as well buy a new pair of speakers.

If I remove the component without replacing it would I have to bridge that connection with some wire or something?

Also with the speakers doing this could it potentially damage the amp? I'm new to all of this, only started looking into all of this two weeks ago, I work in IT with no electronics experience.

Yes, bridge with a wire. You'll have to solder it for best results.

your amp will blow these speakers long before it will be damaged. Also, modern amps have protection circuitry to protect themselves.

gophert said:

Yes, bridge with a wire. You'll have to solder it for best results.

your amp will blow these speakers long before it will be damaged. Also, modern amps have protection circuitry to protect themselves.

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It's a brave (and foolish) man who relies on the amplifier protection circuits to save the amp Also higher quality amps don't usually have it, as it reduces quality slightly.

However, the only way the speaker could damage it (or trigger the protection) is for the speaker to go S/C or low resistance - this is a VERY, VERY rare occurrence, if you blow the speakers they will either go O/C or be driven off centre. One instance where the speaker 'could' go low resistance, is if the amp is already blown, and outputting high current DC directly through the speaker - this fries the voice coil, and it can all short together. This is why many amps have speaker protection circuits, to save the speakers been killed.