PV3 Power Amplifier - Thermal Protect & DDT

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vincegibs
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PV3 Power Amplifier - Thermal Protect & DDT

Post by vincegibs » Tue Jan 25, 2022 1:35 pm

Power Amp: PV3
Speaker: PV115

I am just wondering what's wrong with my power amp the thermal protection & DDT go on & off after 30 mins of use. It drastically affects the sound of the speaker. The speaker that I loaded with it is just 400 watts program that I believe should be fine with this power amp. I always placed it in well-ventilated area and the fan is working just fine so I am not really sure what other factors can trigger this. Hope someone will be able to help. Before I send it to the service center since it is really far from my place. The link below is the actual video that may help. Thanks in advance.


https://drive.google.com/file/d/1vj45xE ... sp=sharing

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Enzo
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Re: PV3 Power Amplifier - Thermal Protect & DDT

Post by Enzo » Tue Jan 25, 2022 7:47 pm

Is the amp getting hot?

vincegibs
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Re: PV3 Power Amplifier - Thermal Protect & DDT

Post by vincegibs » Wed Jan 26, 2022 1:49 am

Enzo wrote:
Tue Jan 25, 2022 7:47 pm
Is the amp getting hot?
No, not at all.

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dak
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Re: PV3 Power Amplifier - Thermal Protect & DDT

Post by dak » Wed Jan 26, 2022 9:04 am

vincegibs wrote:
Tue Jan 25, 2022 1:35 pm
Power Amp: PV3
Speaker: PV115

I am just wondering what's wrong with my power amp the thermal protection & DDT go on & off after 30 mins of use. It drastically affects the sound of the speaker. The speaker that I loaded with it is just 400 watts program that I believe should be fine with this power amp. I always placed it in well-ventilated area and the fan is working just fine so I am not really sure what other factors can trigger this. Hope someone will be able to help. Before I send it to the service center since it is really far from my place. The link below is the actual video that may help. Thanks in advance.


https://drive.google.com/file/d/1vj45xE ... sp=sharing
Well, the respective specs look like the amp should not be having problems. Basically there are three cases to distinguish:
  1. The thermal sensor(s) is wrong about being hot
  2. the thermal sensor(s) is right about being hot
  3. the circuitry evaluating the thermal sensor is misunderstanding it
Case 1 is of course a matter of replacing the sensor.

Now if the amp is not blowing out hot air to a significant degree, the thermal sensor may still be getting hot if the part it is attached to is mostly thermally isolated from the heat sinks (like having developed an air gap for some mechanical reason or are only screwed on loosely with the heat conductive paste masking that problem having dried out and shrunk over time), or the heat sinks are blocked from the air flow of the fan (dust can collect a whole lot between fins, for example).

If the sensor is evaluated by followup circuitry, a bad contact or solder joint is good for a lot of trouble. Bad contacts or solder joints are also temperature-sensitive but the exact manner is a bit unpredictable. Your video shows a bit of erratic behavior rather than protection switching on and staying on for a duration that one would expect typical for cooling off, so that may be a bit of a hint in that direction.

Dookie
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Re: PV3 Power Amplifier - Thermal Protect & DDT

Post by Dookie » Wed Jan 26, 2022 6:50 pm

A little more about your setup. Is the amp in Bridge Mode? Why are the Input sensitivity levels turned down so much? DDT will fire if you clip the input and protect the amp too. Are you clipping the input? If you only running 1 speaker then why are both inputs being used? I don't remember the output power of the amp but a 400 watt program speaker is only 200 watts RMS. Are you sure the speaker is not damaged? Did you check what the impedance of the speaker your hooked up to is? Two things I noticed. It is almost like the amp is seeing a short and quickly muting to protect itself at higher power levels. At a lower level it can handle the short somewhat. Is there a problem with the speaker cables? Short in the cable? What are you using to feed the amp the music?

Here is something you can try. Unhook the speaker cable AT THE AMP. Turn those input sensitivity knobs full clockwise or all the way up. Slowly bring up the source (music) until the DDT lights just start to flash. Does the amp Clip/protect and shut down for a second just like in the video or keep going with the DDT lights just starting to flash? If the amp still shuts down for a second, there may be a problem with the amp. If the DDT lights are just starting to flash with the speakers not hooked up and not clicking off turn the input (music) up some more and see if the amp continues to run fine. Last push hard with the DDT lights on solid. It is safe to run these amps with no speakers plugged in. You only have to do this long enough to notice how it acts with the speakers not plugged in. If the amp doesn't clip/shut off like in the video looking at the front lights with no speaker hooked up that normally means there is an issue AFTER the amp. The DDT / Protection inside is doing its job and protecting the amp. If you push really hard and the source (music) feeding it clips it may protect itself but that would be pushing the source quite hard. Again a shorted speaker wire, impedance too low, damaged speaker internal crossover, a woofer/horn with a shorted or rubbing voice coil after the amp could be the cause of the problem your seeing.

Let us know what you find with the speaker not hook up and report back.

Doug

Dookie
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Re: PV3 Power Amplifier - Thermal Protect & DDT

Post by Dookie » Wed Jan 26, 2022 7:12 pm

I took a look at your amp.

It is 630 watts per channel into a 8 ohm load. Your going into a 8 ohm speaker so that speaker is getting 630 watts peak when those DDT lights just start to flash if your feeding that speaker with 1 amp channel.

If you have it in Bridge mode it has 1900 watts into a 8 ohm load available.

Your speaker is designed to handle 200 watts rms.....

Something I'm not sure of but I'll mention as I don't know if your using Speakon or 1/4 inch cables to feed the speaker. In general, a 1/4 inch input to a speaker and the 1/4 inch tip and sleeve of the speaker cable can handle UP TO 600 watts. If you put around (little under or over) that wattage to the input or the cables the current between the Tip and Sleeve will Arc with that much power or current and may Short out the speaker cable end or speaker contacts. The amp will Protect and the DDT will come on when the amp sees this arc/short. The protection / DDT lowers the wattage, arc stops and the amp quickly turns back on. Are you using 1/4 inch cables to feed the speakers? Try the test above by unhooking the speaker and let us know more about your setup.

That amp is pretty beefy for those speakers. You may be giving it all you can and more now..

Doug

vincegibs
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Re: PV3 Power Amplifier - Thermal Protect & DDT

Post by vincegibs » Sat Feb 12, 2022 7:00 am

Hi guys, sorry for this late reply. It was really a busy week for me.. But I took note of all your suggestions & checked those areas, especially the speaker cables as you mentioned because I remember changing them in one of my gigs. At first, when I turned it on the first hour it was working fine but it started again when it was running for about an hour and a half. Then I realized that I always experience that problem when I am in a small venue and I did not turn up the gain all the way ( usually I set them 12 o'clock) since I was in a small place but never experienced it when I am in a medium to big venues that I had to turn the gain knobs all the way up. So I also did an experiment even the area in my house is small I turned the gain knob all the way up and tried to adjust/control everything in my audio mixer. To my surprise, I did not encounter the "problem" anymore.

I am not really sure though if that was the culprit but it works perfectly now. I am planning to bring these boys to my next gig and will see. btw, my audio source/mixer is Soundcraft Signature 16. Not sure whether the pre-amp is too much for the amp if I limit gain knobs to 12 o'clock that cause the problem. If I encountered any problem on my next gig I will definitely give an update.

Thanks.

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