Here i am again with an interesting one, this time.
So i have this XXL INSIDE DX16 box in front of me right now, since i took it from a guy who had plenty of rotten speakers and wanted to get rid of them, i expected this to be faulty.
In fact, when i turned it on, it seemed to work just fine. But i was playing music at low level.
When i turned on the gain something strange happens. The tweeter works, the woofer starts to distort (i think, i mean.. I have no big experience with PA, so it might be normal for cheap systems), but foremost it stops playing for a second and then the volume rises again, arriving to normal level and then it stops again for a second, and then it rises etc etc.
Like if a capacitor is charging and decharging.
I always use the bulb limiter, i noticed that during this rise of the woofer there isn't a rise of current demand, the light remains constantly lit.
I asked the manufacturer for schematic, hopefully they'll provide it to me.
But still.. I am wondering, i couldn't explain this behaviour thinkin to out transistors damage or so. Of course i'm a rookie, i basically have no idea.
I'll be grateful for any clue whatsoever.. 🙂
Have a nice day,
Andre
So i have this XXL INSIDE DX16 box in front of me right now, since i took it from a guy who had plenty of rotten speakers and wanted to get rid of them, i expected this to be faulty.
In fact, when i turned it on, it seemed to work just fine. But i was playing music at low level.
When i turned on the gain something strange happens. The tweeter works, the woofer starts to distort (i think, i mean.. I have no big experience with PA, so it might be normal for cheap systems), but foremost it stops playing for a second and then the volume rises again, arriving to normal level and then it stops again for a second, and then it rises etc etc.
Like if a capacitor is charging and decharging.
I always use the bulb limiter, i noticed that during this rise of the woofer there isn't a rise of current demand, the light remains constantly lit.
I asked the manufacturer for schematic, hopefully they'll provide it to me.
But still.. I am wondering, i couldn't explain this behaviour thinkin to out transistors damage or so. Of course i'm a rookie, i basically have no idea.
I'll be grateful for any clue whatsoever.. 🙂
Have a nice day,
Andre
It's used in older designs to protect the HF driver. Light bulbs are a conveniently available non-linear resistor. Their resistance increases as they get hotter. It's a simple but reasonably effective way to introduce power compression on the HF side with the added bonus that you can size the bulb to burn out right before the HF driver does.
Peavey :: SoundGuard
I'm fully aware of using a bulb to protect the tweeter, but that's presumably not what's happening here.
I'm suspecting he's using a bulb in series with the amplifier mains lead?, which is very probably causing the symptoms he described - particularly as he mentioned it's lit up,which it shouldn't be - but of course it shouldn't be there in actual use anyway.
Agree with Nigel, if the amp is no longer blowing fuses (making the bulb glow brightly at idle) then get rid of it, it is interfering with the amp's operation.
which model X speaker do you have? the DX 16 designation is the dsp (acoustic modeler program) that much of their product line has.
the "dim bulb tester" behavior seems to spell "smps in distress!" given that the speakers are still functional.
are your kemptons still working?
the "dim bulb tester" behavior seems to spell "smps in distress!" given that the speakers are still functional.
are your kemptons still working?
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Yup - sounds like undervoltage lockout. Dim bulbs only work properly on non-switching amps and non-switching supplies. Use the bulb to limit things when testing the power supply alone - unloaded. Once the supply can be trusted, dispense with the bulb. A good SMPS should have appropriate current limiting and shut down in the event of a fault in the amplifier.
Hi there,
In fact i forgot to say that the main fuse was blown, so i thought there could have been some shorted out, as usual. Therefore after changin the fuse i plugged the box in the bulb limiter.
Actually i didn't know it would harm, i mean... I thought until very high volume the limiter wouldn't be an issue at all, especially considering that the bulb is a low wattage one.
Anyway.. I plugged in without limiter, it works just fine.
That dsp thing is quite nice to have... No audiophile quality, but i heard worser stuff.
Sorry guys! 😀
2 things:
1 could someone explain me what happened with the limiter? I mean.. Is some capacitor involved or how is it possible to have that 2 second gradual rise?
2 turk! So great you showed up! Hope you are fine, i owe you a lot.. Btw when you come visit me? The kemptons are fine, i guess. I saw this friend of mine, the owner, a couple of days ago. He is the ice cream man of my town. He gave me 1 kg of ice cream, for free. So i guess the spkrz are still workin... 😀 (its a true story actually)
In fact i forgot to say that the main fuse was blown, so i thought there could have been some shorted out, as usual. Therefore after changin the fuse i plugged the box in the bulb limiter.
Actually i didn't know it would harm, i mean... I thought until very high volume the limiter wouldn't be an issue at all, especially considering that the bulb is a low wattage one.
Anyway.. I plugged in without limiter, it works just fine.
That dsp thing is quite nice to have... No audiophile quality, but i heard worser stuff.
Sorry guys! 😀
2 things:
1 could someone explain me what happened with the limiter? I mean.. Is some capacitor involved or how is it possible to have that 2 second gradual rise?
2 turk! So great you showed up! Hope you are fine, i owe you a lot.. Btw when you come visit me? The kemptons are fine, i guess. I saw this friend of mine, the owner, a couple of days ago. He is the ice cream man of my town. He gave me 1 kg of ice cream, for free. So i guess the spkrz are still workin... 😀 (its a true story actually)
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