Hello,
New here, hoping to get some ideas on a pair of JPW SS 553's. They have some sort of buit-in protection that kicks in when you crank things up. Not a fan of this feature, I'm totally fine with some distortion at higher volumes. If they get damaged, they get damaged and I'll go buy something better. So I have two questions.
Can I disable this feature somehow?
If not, what can I do to minimize this? Do I need a higher powered AMP? Running an old Fisher Studio Standard rated @ 100W per chan at the moment.
New here, hoping to get some ideas on a pair of JPW SS 553's. They have some sort of buit-in protection that kicks in when you crank things up. Not a fan of this feature, I'm totally fine with some distortion at higher volumes. If they get damaged, they get damaged and I'll go buy something better. So I have two questions.
Can I disable this feature somehow?
If not, what can I do to minimize this? Do I need a higher powered AMP? Running an old Fisher Studio Standard rated @ 100W per chan at the moment.
Of course you can disable this feature. You need to by-pass the protection thermistor in the loudspeakers crossover board with a piece of wire.
But speaker protection is not for preventing distortion in the first place, it is there for preventing voice coil burning.
But speaker protection is not for preventing distortion in the first place, it is there for preventing voice coil burning.
I'm curious about you hearing it kicking in. Would you have any trouble identifying the method of protection, you could post a schematic or photos.
Whether you need a bigger amp depends on what you hear. Do you usually push it until the tweeter sounds overloaded?
Whether you need a bigger amp depends on what you hear. Do you usually push it until the tweeter sounds overloaded?
The PRO-TECH overload protection devices can become oversensitive with age. You can simply bypass them as denibeni says.
These little components are easily identifiable on the crossover board. Post a photograph of the board if you need help in identifying them.
These little components are easily identifiable on the crossover board. Post a photograph of the board if you need help in identifying them.
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@denibeni - Excellent news, wire and iron standing by... How long does it take to burn a voice coil? Is it best to bypass or remove the component entirely? Voice coil burning sounds like something that happens progressively, or is it? Does this damage the tweeters or drivers, or both?
@AllenB - the volume reduces and goes really flat sounding. I am not trained in all things electrical so some help would be cool. I don't really push it tbh, it happens at less than 1/2 on the volume knob.
@Galu - A quick search seems to indicate the thermistors are the round yellow objects. Not sure which one(s) to bypass.
@AllenB - the volume reduces and goes really flat sounding. I am not trained in all things electrical so some help would be cool. I don't really push it tbh, it happens at less than 1/2 on the volume knob.
@Galu - A quick search seems to indicate the thermistors are the round yellow objects. Not sure which one(s) to bypass.
A polyswitch has a positive temperature coefficient. It shows a low resistance when cold, but heats up with use and increases in resistance.
It makes sense to use these in series, but I'd check this regardless. They could then be bypassed by shorting them.
One unrecommended way I might have done this is by turning them like a key, then soldering.
It makes sense to use these in series, but I'd check this regardless. They could then be bypassed by shorting them.
One unrecommended way I might have done this is by turning them like a key, then soldering.
It looks like each driver has its own thermistor, usually these are in series with the drivers. If you want to be sure, bypass them all or remove them from the PCB and replace them with wire. If you just solder together their legs (with wire), you can easily reverse this modification in the future.
I don't know exactly how voice coil burning happens, but i think it depends on the actual situation, like how much power you sent to the speakers, how distorted the signal etc.
I don't know exactly how voice coil burning happens, but i think it depends on the actual situation, like how much power you sent to the speakers, how distorted the signal etc.
So just to double check, the yellow things are the thermistors?
How exactly is this done?
How exactly is this done?
If you check closely, there are two + connector for each driver, for example B+ and B+P, where one is for the bass driver positive pole (B+) and the another is the bass driver positive pole with protection (B+P), same for the other drivers i guess.
So IF i am right, you can simply connect the drivers either to the protected or the unprotected leg, depending on whether you want the protection or not.
So IF i am right, you can simply connect the drivers either to the protected or the unprotected leg, depending on whether you want the protection or not.
Once you take a nice clean photo from the bottom side of the board and one from upper side, someone will draw the schematic to clear which parts go where.
THAT makes perfect sense. I checked the other speaker, and yes, all the positive leads from each of the 3 drivers connect to the +P terminals. I am going to test with them connected to the + terminals and see what happens.
I wish I could get a good shot of the bottom of the board, but for now, I don't
want to un-solder those 4 main connectors coming thru the board center.
Hmm, I just ran into something weird and un-related. On one of the speakers, the red+ where it connects to the bass driver...is connected to the marked -terminal. This appears backwards. It's not that way on the other speaker. Any chance that is intentional? Or was it a mistake made at the factory?
Yes, they are called positecs (positive temperature coefficient thermistors). Here they are in a Mordaunt Short crossover:
Attachments
The same cabling is required for both loudspeakers if there is a pair from the same model (and revision, if the capacitor values are the same there is a good chance for a matching pair).
But which cabling is right and which is wrong, it is difficult to say from here.
If you mean this is a polarity mismatch in the wiring between the speakers and you don't have a measuring mic, you need to trust your ears to tell which is right.
It looks like maybe someone mess with the wiring before you and plugged back the wires in random.
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They are there for speaker overload protection as must be the identical components in your crossover.
I can not find any information with regard to the B+ and B+P connections on the drivers, but perhaps denibeni could tell us more.
Regarding the red wire - I can only think that it should be connected to the positive bass driver connection.
If one of the bass drivers has been reverse wired in error then your speaker system will not have been producing full bass - perhaps you've been turning up the volume to compensate for the bass cancellation!
Connect red to + and listen for the difference.
Check that the midrange and tweeter connections are also the same for left and right. I would guess that the woofer connections should be red on positive. This could not only have affected the crossover region on this side but the bass overall.
Mission accomplished! No more attenuation! As far as the mis-wiring I mentioned in post #12, that was my error, I got my up and down mixed up in an image I was looking at. Many thanks to all who helped, esp you denibeni for your insight. Now that I found this place, I think I'll poke arond some and see what everyone's up to.
I did as denibeni suggested, connected the positive leads to the board headers marked + instead of the ones marked +P
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