Hi folks, just wondering if somebody can help me with this problem. I dont think i have done anything i shouldn't of, no mods or anything. Just got no.1 out of box, wired up correct polarity 24v dc (from 2x golf buggy batteries), connected to 2 x 200w 8 ohm pa speakers. worked fine, never pushed into clipping, after about 8 hrs use, 1 day i turned it on, and it kept popping and smoking and blowing my inline fuse (sounded like it as coming from the caps) green light comes on with fan but no sound, keeps popping and smoking.
Spoke to parts express (ebay) about this and they promptly issued me a new one.
Plugged that in, all wired correctly, after about 3 hrs use, turned it on another day and no sound on any channel, no pops/smokes or any sign of damage, just no sound!
Only 2 things i did that i could think may have upset them was
1:
run 12v from 1 of my 12v bats (2x 12v in series 24v supply) to power my effects pedal at the same time (would this be likely to cause such a fatality?)
2: Didnt have a switch on the supply cable so sometimes when connecting to the batteries it would take me a few quick on/offs in succesion until i had clamped the cable to the batteries terminals (could this kill it?)
Otherwise i am thinking that there is a dodgy batch being supplied by partsexpress.com, anyone elese bought from them?
Thanks in advance, jimi
Spoke to parts express (ebay) about this and they promptly issued me a new one.
Plugged that in, all wired correctly, after about 3 hrs use, turned it on another day and no sound on any channel, no pops/smokes or any sign of damage, just no sound!
Only 2 things i did that i could think may have upset them was
1:
run 12v from 1 of my 12v bats (2x 12v in series 24v supply) to power my effects pedal at the same time (would this be likely to cause such a fatality?)
2: Didnt have a switch on the supply cable so sometimes when connecting to the batteries it would take me a few quick on/offs in succesion until i had clamped the cable to the batteries terminals (could this kill it?)
Otherwise i am thinking that there is a dodgy batch being supplied by partsexpress.com, anyone elese bought from them?
Thanks in advance, jimi
We used to do ruggedness testing on battery powered devices by doing just that, erratic power supply connections
to large batteries by scraping the contacts repeatedly. It was a very demanding test, and would often cause the devices to fail.
I wouldn't recommend doing this.
Thanks to you all for speedy replies. @DUG the chips are TC2000 TP2050 (TK2050) batteries were not under charge but were passing out 12v to other devices at the same time (now using seperate 12v source incase) @Jplesset, thanks but amps are rated to 30v. @rayma, thanks, I hope this is the reason, dont want to kill another. I am going to take failed amps to an electrician to do an autopsy, will post results here soon.
You want to put a TVS diode at the input (VCC to GND) to prevent this in a car setup, like the SAC26:
SAC26 - SAC Series - Leaded from TVS Diodes - Littelfuse
It provides crowbar like functionality/protection against surge failures.
SAC26 - SAC Series - Leaded from TVS Diodes - Littelfuse
It provides crowbar like functionality/protection against surge failures.
Thanks doctor more, will look into that. This is not in a car though,it is in a bike trailer.
@counterculture
I have 4 x 8 ohm speakers but was only driving 2 when it blew.Each channel can take 4 ohms so connecting 2 speakers in parallel to 2 of the 4 channels. When it blew I had 1 speaker to 1 channel and another speaker to next channel putting up 8 ohms resistance. Amp info says it's fine to leave unused channels...
@counterculture
I have 4 x 8 ohm speakers but was only driving 2 when it blew.Each channel can take 4 ohms so connecting 2 speakers in parallel to 2 of the 4 channels. When it blew I had 1 speaker to 1 channel and another speaker to next channel putting up 8 ohms resistance. Amp info says it's fine to leave unused channels...
@doctor mode. do you think I should get this instead as the amp is designed to run most efficiently at 30v so will be giving it this much juice?
SAC30 Littelfuse | Mouser
Only problem is 400w into 30v is 16amps. Looks like this fuse can only take 10 amps, is that correct?
SAC30 Littelfuse | Mouser
Only problem is 400w into 30v is 16amps. Looks like this fuse can only take 10 amps, is that correct?
Dude, these are suppressor-diodes not fuses (Littlefuse is the name of the company).
As you use 2 SLA batteries, your max VCC will be like 29.4V when "overcharged", the SAC26 will clamp this down to 28.90V(min).
Normally you'll have like 22-27V from the two batteries. The TVS is meant to be mounted in parallel to your board inputs.
Transient-voltage-suppression diode - Wikipedia, the free encyclopedia
Their're to be used as an overvoltage protection here to not frying your boards by transients.
As you use 2 SLA batteries, your max VCC will be like 29.4V when "overcharged", the SAC26 will clamp this down to 28.90V(min).
Normally you'll have like 22-27V from the two batteries. The TVS is meant to be mounted in parallel to your board inputs.
Transient-voltage-suppression diode - Wikipedia, the free encyclopedia
Their're to be used as an overvoltage protection here to not frying your boards by transients.
Ah ok thanks, although I also have a 6v I am going to add in to the mix to get full 30v.amp company said amp is rated to 35v max so not worried if bats are fully charged.
Just thought of something though! Amp is 100w per channel, speakers can handle over 200 watts each, with 2 cabs on 1 channel I am at 4 ohms which is safe but could the overrated cab watts kill my amp? Not driving the amp into distortion and it is only using between 3 and 4 amp current with all 4 speakers plugged in so can't be driving at its limit I don't think. Any ideas on this? I know amp should be more powerful than speaker but if not driven hard is this ok?
Just thought of something though! Amp is 100w per channel, speakers can handle over 200 watts each, with 2 cabs on 1 channel I am at 4 ohms which is safe but could the overrated cab watts kill my amp? Not driving the amp into distortion and it is only using between 3 and 4 amp current with all 4 speakers plugged in so can't be driving at its limit I don't think. Any ideas on this? I know amp should be more powerful than speaker but if not driven hard is this ok?
As you say, the power rating of the speakers means they can handle over 200W.
As long as the amps can handle the current/impedance, you are OK, and even if not, you don't blow up the amp, you just get clipping/limiting/distortion.
No, that is the wrong way around. If you don't want to blow up your speakers, the speaker rating should be higher than that of the amp.
How would a 100 W amplifier even know if the speaker it is driving is rated for 10W or 1000W? The amp will have exactly the same amount of distortion at 100W. !00W will blow the 10W speaker but not the 1000W speaker.
A speaker rating tells you what power you can safely feed it.
If you say so..
Presumed that this is a TK2050 based board, lets have a look into the datasheet.
Its not the "power" which destroys the speaker, it's the amount of distortion. (i.e. when sine signal becomes square-wave-like-signal)
Despite that, their is a huge difference between average, rms, peak, etc. power ratings.
This belongs to all and every amp, but hey, you're right..
Presumed that this is a TK2050 based board, lets have a look into the datasheet.
Its not the "power" which destroys the speaker, it's the amount of distortion. (i.e. when sine signal becomes square-wave-like-signal)
Despite that, their is a huge difference between average, rms, peak, etc. power ratings.
This belongs to all and every amp, but hey, you're right..
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It is not the amount of distortion that destroys the speaker, it is the power.
There are two major ways an amplifier can destroy a speaker. One is mechanical failure due to over-excursion - this is determined by amplitude (power) and not by distortion, and is a concern at low frequencies. Thus distortion doesn't affect this failure mode, but maximum power does.
The other failure mode is burning of coil/connection wire, caused by excessive power. Yes, at dire clipping (output is a square wave) the produced RMS power is higher than the sine power, and affects a tweeter more due to a higher HF content, but you really have to be into serious clipping, and then the primary reason is still excessive power.
If you have a 10W amp, you won't be able to destroy a speaker rated for 100W, no matter how much clipping and distortion you have.
So the advice is "make sure your speaker has a power rating that is equal or greater than that of your amp, and avoid extreme clipping".
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due to (excessive) clipping. So the primary reason for excessive power is clipping/distortion.
Lets take a look here:
Why Do Tweeters Blow When Amplifiers Distort?
The conclusions of that article are based on rather artificial simulations, but as you seem to believe it is valid, I suggest you look at what he actually says:
Speakers are damaged by power. Clipping can increase the amount of power in a speaker, but even in worst case, only by a factor of the square root of 2 (or 40%).
As I keep saying, you can't blow a 100W speaker with a 10W amp. You can easily blow a 10W speaker with a 100W amp. Do you disagree?
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