Distortion is a function of output amplitude in relation to total available voltage swing.
Yes. But a 10W amp run with volume at 50% sounds as good as a 100W amp run with the volume at 50%, just not as loud.
That has in any case nothing to do with the issue at hand. I stated that the loudspeaker should have a power rating that is at least that of the amp. The document you linked to argued that there should be even more of a margin (so that the speaker power rating is significantly more than that of the amp). You stated that that was wrong, and the amp should have a power rating that is higher than the speaker.
I suggest you do a simple test. Take a 200W amp, and a speaker rated at 50W. Run the amp with a sine signal that results in 150W output power - no clipping, no distortion. Leave the combination on for a couple of hours.
For sure this will fail, but that was not the point when I said, that a 10W amp at 10W sounds worse than a 100W at the same level. While the first will most likely sound bad due to distortion, the second one will sound well.
Anyway. 🙂
Anyway. 🙂
So you're actually loading the amp with 4 ohms. Is it rated for 4 ohms?
Perhaps if you provided a link to the specs we could look up these things ourselves.
Perhaps if you provided a link to the specs we could look up these things ourselves.
Haha, thanks guys. I did say "I know there are mixed thoughts on this". So either way it doesn't look like that was the cause for my 2 dead amps then. I'm down to my last one so I really want to know what killed the other two! Luckily I got refunds on them both from parts express, they didn't even want the dead ones back cos I am in the UK and they are in USA! So going to try and get them fixed or at least autopsy'd soon.
i guess they are something like 4 x 100watt class d audio amplifier board sta508
Seems OK with 4 ohm load, and in any case, with an impedance that is too low would lead to current limiting, not amp blowing.
I wonder if it is a power supply issue?
My guess would be voltage spjkes from the alternator. Like doctormord suggested, use a suppressor diode.
Link to the amp
4x100W @ 4 Ohm TK2050 Class-T Audio Amplifier Board Only 320-335 | eBay
It's cool for 4 ohms. By the way the amp isn't in a car so no alternator. It is mounted inside one of the cabs on a shopping trolley/bmx/wheelchair hybrid. Maybe I created voltage spikes by tapping off 12v from the 24v To power my looppedals or maybe cos I didn't have a on/off switch. now being super careful so fingers crossed. They are great sounding amps until they stop working!
4x100W @ 4 Ohm TK2050 Class-T Audio Amplifier Board Only 320-335 | eBay
It's cool for 4 ohms. By the way the amp isn't in a car so no alternator. It is mounted inside one of the cabs on a shopping trolley/bmx/wheelchair hybrid. Maybe I created voltage spikes by tapping off 12v from the 24v To power my looppedals or maybe cos I didn't have a on/off switch. now being super careful so fingers crossed. They are great sounding amps until they stop working!
It supposedly has over/under voltage protection, over current protection and over temperature protection, and works on 10-30V, so should be pretty hard to blow up. How did you tap the 12V off the 24V?
Is there any chance that you ran the amps without any load (speaker) connected?
Is there any chance that you ran the amps without any load (speaker) connected?
Hmm. I took off 12v from one of the batteries that were in the 24v bank. The instructions say it's fine to leave the channels you aren't using empty without harming the amp, so other 2 channels are always without load. No volume control I can find (apparently there is a notch switch somewhere on the board for 3 levels of amplification but never found it, any ideas on that). I think it could be possible that I blew the preamp or input stage chip if that's a thing, as I was driving from a mixer. If I really crank the input on an iPod I can cause clipping but amp is only drawing 1 ampeare at 30v even at this volume so only using 30watts right? I am guessing this means the output stage isn't being challenged in the slightest but the input stage is?? If I could find this amplification switch I could keep the input lower and drive the output harder perhaps. Could it be under the onboard heatsink/fan arrangement? Will look at the dead ones further. Thanks to all of you in helping to solve this mystery!! Jimi
I think it is extremely unlikely that you have blown the input stage - even really heavy overdriving won't damage it. I am concerned about having the outputs empty - class D amps can generate very high voltages in the output choke if there aren't any clamp diodes.
I also wonder if taking the 12V off the 24V batteries could somehow have caused a 12V DC offset at the input (in case the common ground point ends up being 12V off).
I also wonder if taking the 12V off the 24V batteries could somehow have caused a 12V DC offset at the input (in case the common ground point ends up being 12V off).
Took the heatsink off one of the blown ones and at least 2 of the chips look a bit frazzled, will try to upload some pics...
I know on irs2092 based class d amplifiers it is unwise to leave channels unconnected.
You can end up with one of two states.
1/ The output does not oscillate and sits at +17VDC.
2/ The output does oscillate but the output filter inductors rings with a very high voltage which sometimes kills the output filter capacitor.
Hmm is there a way to block them off when not in use somehow? Can't always carry an 8 stack with me!!
1/ Connect an 8 ohm resistor to the output.
or
2/ Fit higher voltage output filter capacitors so they don't mind ringing voltages.
On my irs2029 design I put in 250VDC capacitors on the output filter to get around the problem.
or
2/ Fit higher voltage output filter capacitors so they don't mind ringing voltages.
On my irs2029 design I put in 250VDC capacitors on the output filter to get around the problem.
The 8 ohm resistor will dissipate a fair bit of heat. One way to deal with the ringing voltage is to use diodes to clamp the output to the supply rails.
Chips indeed are the sta508 and not tk2050 PE is selling, manual/data for tk2050 might not be totally accurate. Seems VCC and GND pins are burnt, not outputpins?
Thanks, I want the ability of plugging in more speakers as and when so don't really want to do any modifications to the board ideally. Just to clarify, there are 4 x phono inputs, I am only sending music to 1 and 2 And speakers only plugged into 1 and 2, if no input in 3 and 4 wouldn't this mean no output from 3 and 4 therefore no harm? Otherwise I was thinking what about connecting 2 of the smallest 8 ohm speakers I can find to 3 and 4 when not in use?
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