Re-using sub and car amp for PC sound

[Tai12]

Hello,

I have a PDX m12 amplifier and a alpine type x subwoofer that was used for a car audio awhile back. Both items are discontinued so awhile ago.

Goal is to have a couple speakers hooked up to PC but any chance I can hook up the amp sub combo at the same time? Sounds like it would be impractical or not worth. But if there was a way to do it wouldn't mine learning. I do not know anything but i did watch a video on DACs, so i got that part down.

Someone else stated they are doing the setup below. Would this apply the same way? Thanks

"
I just ordered up a Topping DX3Pro+ DAC/Amp and a Topping PA3s amplifier. As I understand it, I'll be able to connect as follows:

PC USB --> DX3Pro+ --> RCA in on SE8 Sub --> RCA out on SE8 Sub --> PA3s RCA in

All I should have to do is gain match the amp and the sub, set crossover and HPF on the sub and I'll have variable volume control at the DX3Pro+, while cutting sub 60Hz frequencies to the B1+ speakers."

 

[Tai12]

With the understanding a PSU would have to be inserted along the way

 

[AnalogSteph]

You're still missing a crossover, plus my understanding is that car audio subs don't work terribly well outside a car... you could recycle the Alpine driver in a DIY sub though, and find a plate amp with crossover function for that.

Do you have anything in particular in mind for the main speakers yet? That would affect what sort of I/O you need among other things.

 

[Doodski]

The sub has 4- 25 Amp fuses.
At idle the amp draws 2.1A.
The dyno test at 4 Ohms the amp drew 142A peak @1% THD and 161A peak at clipping.
The 2 Ohm test resulted in 166.6A peak @1% THD and at clipping it is 190A peak.

So you are going to need a large power supply. After ~50A @13.4VDC the rack mount power supplies require 208-240VAC mains power. I only know of one Hewlett Packard rack mount power supply that puts out 0-20VDC with a regulated 50ADC with a 120VAC mains special order option installed. They are rare as hens' teeth and you might never even find one. If you want one of those they cost about $600 to $1200 depending on condition and options on the used market.

Otherwise you will use a car battery and connect a charger to it. The car batteries generally off gas hydrogen sulfide as they operate and charge and that is explosive. I have seen 3 car battery explosions when I was assembling/wiring up oil and gas equipment. The noobs where using a charger set on high charge rate on a car battery and welding nearby at the same time and blew up 3 batteries over a few weeks period. sigh*... I giggled to myself, the engineers came down and checked it out and advised the welder not to weld near the batteries and it was business as usual. What I am getting at is that amp is a beast for current draw. You'll need a big battery. We experienced 3 batteries exploding and spreading acid and plastic chunks all over and that was in a huge industrial building that was concrete and steel everywhere and so nothing really to catch fire other than a metal chemical fracking trailer with lotsa wires in it that we where building. If this happens in your home it will be very very tragical!

This is serious stuff so make sure you don't cause a explosion and blow out the windows or walls and start a fire too. My favorite method is put the battery outside, run wires inside and do it that way or...>

... use a battery that does not off gas hydrogen sulfide? Get a SLA or sealed lead acid battery that does not off gas hydrogen sulfide outside of the battery. Instead, these gasses recombine into the electrolyte inside the battery, which is why SLA batteries don’t need to have distilled water added to them the way traditional lead acid batteries do. Even though they don’t release gasses on a regular basis, an SLA battery can still vent during certain situations. If the battery is overcharged, it can boil the electrolyte inside, producing too much pressure for the battery to hold onto. Likewise, if the battery is charged too quickly, the hydrogen sulfide gas can build up faster than it is able to recombine with the water inside. If either of these situations occurs, a SLA battery will vent gasses through a one-way pop-off valve in the battery’s body.

So after much adieu I can see how you will now see that a car battery is a horrible idea for in-home use no matter which kind. Even lithium batteries off gas hydrogen. So they are not really safe for in-home in the large quantity required.

So for long term safety and electrical security too a big AC mains powered 13.4VDC power supply is really the way to go. But you will be limited in the Alpine amp's output due to the AC to DC power transfer characteristics of the AC powered DC output power supply limiting you to 50ADC at 0-20VDC.

All in all working big car audio gear into a home is not easy and requires lotsa thought and safety measures.

 

[Tai12]

You're still missing a crossover, plus my understanding is that car audio subs don't work terribly well outside a car... you could recycle the Alpine driver in a DIY sub though, and find a plate amp with crossover function for that.

Do you have anything in particular in mind for the main speakers yet? That would affect what sort of I/O you need among other things.

---- I do not know what Alpine Driver in a DIY sub entails. I have no main speakers in mind, only would be interested in something that doesn't trap me with that setup. I'd like a couple regular book shelf speakers, or generally any reasonably sized speakers I could place on a desk. I'm really interested if i can provide audio from a PC while incorporating the Sub. So whatever gets me there.

The sub has 4- 25 Amp fuses.
At idle the amp draws 2.1A.
The dyno test at 4 Ohms the amp drew 142A peak @1% THD and 161A peak at clipping.
The 2 Ohm test resulted in 166.6A peak @1% THD and at clipping it is 190A peak.

--- I know enough about batteries to know that i don't care to fuck with them at all. Most of your battery talk is over my head. But I will share a picture here of the amp. Also a random story here, I was quickly removing this unit from my car and decided to use a metal knife to cut the cable running from the sub to the wire size converter towards the battery. The knife sparked and burned a quarter inch through itself as i cut the 0 gauge wire connection, and the fuse near the car battery looked.. blown or different. lol. I was wearing rubber soles in a parking lot at the time but glad that worked out ok besides the fuses. I'd like to get some solution to power the sub since I have not since that occurred.
I will say I ran this on the smallest Toyota Sedan available and i don't think i was ever able to push the sub to the limits, at all. The interior lights of the car and headlights would noticeably flicker at high volume etc. But I imagine I could get it operational with some sort of psu.
I'm not too worried about price but more concerned about practicality and the ability to switch out speakers, or apply it to a different home system, if that makes sense.

 

[Doodski]

--- I know enough about batteries to know that i don't care to fuck with them at all. Most of your battery talk is over my head.

Batteries be bad! lol...

Also a random story here, I was quickly removing this unit from my car and decided to use a metal knife to cut the cable running from the sub to the wire size converter towards the battery. The knife sparked and burned a quarter inch through itself as i cut the 0 gauge wire connection, and the fuse near the car battery looked.. blown or different. lol.

I have a similar story. I worked as a car audio installer when I was in my teens and a guy with his new car stereo wanted to be driving to the lake before dark because after dark the deer get really bad and that meant we needed to install his new car stereo in about 40 minutes. So... He asked me what he can do to speed up the installation. I said run the 14G power wire from the battery to to the location of the amplifier. He connected the battery to the wire and then proceeded to pull the wire through the firewall. It was jammed and so he went to the engine compartment and started pulling it back the other way. He cut through the wire insulation with the firewall metal and the wire now shorted to ground melted and burned all around his hands where he had wrapped the wire to pull harder. He made it to the lake I found out after but he was sore and burned.

I was wearing rubber soles in a parking lot at the time but glad that worked out ok

No worries with 12 to13.4VDC. Not enough voltage to overcome the skin resistance and electrocute.

I imagine I could get it operational with some sort of psu.

You could, the PSU are out there and one just needs to find one based on budget because the sky is the limit so choose a budget and then start surfing that. Based on your budget I might recommend you go to 120VAC mains powered home audio gear instead of messing with 13.4VDC stuff.

I'm not too worried about price but more concerned about practicality and the ability to switch out speakers, or apply it to a different home system, if that makes sense.

Refer back to the previous comment because this and that are related.

 

[Cars-N-Cans]

Sounds like shades of my brother lol... He used a head unit and sub along with amps and a 12V battery that he took outside once a week to charge. The head unit was stuffed into one of the bays under the CD ROM with a bunch of hacking and epoxy. Not pretty but it worked in a fashion.

To be honest, the only part I would consider reusing would be the actual sub driver. You will want to make another box for it since it wont sound good in a room. Those are made for high SPLs at the expense of uniformity of response, and cars act quite a bit differently than a large room. An alternative is to use it "as-is", buy a separate amp, and use DSP to try and tame the car sub enough to make it reasonably flat in the room. I have done this, but the only thing I could say about it is it was an easy way to piss the neighbors off. Other than that, it didn't have much positive going for it other than sounding like a gigantic Bluetooth speaker.

For powering the amp, you could use a large 12V transformer from a lead-acid charger out of a UPS. But note that the actual voltage you would end up getting would be ~12V x 1.41, or 17V once its rectified and smoothed, which is likely too much. Off the top of my head, the max input voltage of most consumer car audio amps is around 16V, and unregulated it could easily float up to 20V, which could be a bad day for electrolytic caps and mosfets in the PSU. Having also done stuff like this as well, using a shunt or pass regulator made of an IC and multiple pass transistors can potentially be used to bring the transformer down to around 16-17V, but that will involve lots and lots of heat.

Easiest solution is just get a standard audio amp that runs off of 120V/240V and use that, instead. There are plenty of class-D options around to use.

 

[Cars-N-Cans]

--- I know enough about batteries to know that i don't care to fuck with them at all. Most of your battery talk is over my head. But I will share a picture here of the amp. Also a random story here, I was quickly removing this unit from my car and decided to use a metal knife to cut the cable running from the sub to the wire size converter towards the battery. The knife sparked and burned a quarter inch through itself as i cut the 0 gauge wire connection, and the fuse near the car battery looked.. blown or different. lol. I was wearing rubber soles in a parking lot at the time but glad that worked out ok besides the fuses. I'd like to get some solution to power the sub since I have not since that occurred.

The 12V from the car is not dangerous voltage wise, but its quite energetic from a perspective of current . I shorted a car starter with a small wrench once, and it immediately turned into a lightbulb from all the current it was passing before burning clear. I have heard other people who have ended up welding various tools to parts of the vehicle after not removing the negative terminal first. Lead acids are really good at that sort of thing since they are designed to provide loads of current for short periods of time to crank the engine over.

Edit: "Welding" with a car battery:

Not something I'd really consider trying since the electrolyte can boil and/or blow up. Have had that happen from a bad starter and its a mess. Somehow the car still made it home, but there were just random lead plates with wires hooked to them where the battery was. The rest of the case was gone, and it made quite a bang. I suspect one of the lead bus bars melted and created a spark inside. Not something I'd want to be near when it happens.

 

[OldHvyMec]

Sorry to report a 12VDC lead acid battery in a Toyota Camry can kill you deader than a door nail. It's NEVER the voltage it's always the amperage.

That little welding example above gives an idea what a little CAR battery can do. Think of 4 G-31 batteries. I've walked up on 2 different people
on the ground, behind jumping heavy equipment. Both times they were out cold and one was dead. No pulse! They rescued the guy and he made
a complete recovery. I had to inspect several battery explosions in one company over a 19 year period. Every time it was a procedural issue. Like smelling
heavy battery fumes and STILL attaching cables to jump equipment. BOOM!

Never under estimate any battery or capacitor banks. NEVER stand in front of ANY equipment when starting or jumping them.
NO MATTER THE REASON. MOVE YOUR BODY FROM IN FRONT OF, OR BETWEEN THE VEHICLES.

If a battery has a low liquid content the chances of an explosion go WAY up... There is a lot of space between top and bottom plates
and the case. One cell of hydrogen gas is lethal if it ignites. Think of 2 or more, like a rip over several cells and a few batteries. I've seen complete battery boxes
blown off tractors because the bottom of the battery box was wood vs metal. The batteries get damaged from something flipping up and tearing the bottom
on a few cells. You start something like that it can blow up.

I haven't seen a fuel fire on a car in a while, it is usually a hot wire going to ground and a fire starts. Fuel just adds to the problem once a NEW car goes up.
They stink up the neighborhood for months too. We had one go up 30 yards from my front door. It stunk every morning until they cleaned the street.
You could see the fire start under the car from a wire. It took the fire department 14 minutes to respond. They almost caught the fire truck on fire. I think
something weird was going on. 14 minutes? Puff Puff pass I think.. At fires you drop acid dude, don't smoke weed. Rookies!

Regards

 

[Cars-N-Cans]

Sorry to report a 12VDC lead acid battery in a Toyota Camry can kill you deader than a door nail. It's NEVER the voltage it's always the amperage.

That's not true, actually. Skin has a fairly high resistance. Remember ohms law? E = IR? If your skin has several kiloohms of resistance, very little current will flow. The only exception would be if the wire comes in contact with a mucous membrane, as then current has a direct path through the body. In order to kill you, current has to be made to flow through the effective series resistance of your body. If we take a nominal resistance of about 2kΩ, and a lethal current of about 65mA, we are at around 130V, which is near to mains voltage in the US, which is why some electric shocks from mains powered appliances can be one-way trips. This is doubly-so for something like a vending machine or some other device that is near a wet location like an outdoor park where bare feet might be present. Those its mandatory to have GFCIs to try and prevent leakage current from zapping unwary users. There have been fatalities with this scenario.

But, I have a stack of 12V lead-acid batteries. Even hooking them all together only gives around 48VDC. Painful, but probably not deadly. But it is above 40V, which means there is some hazard, there. However with just one, the only real hazard will be lead poisoning if I touch it, and even that is overexaggerated from experience using 60/40 solder. Just have to be sure to wash up afterwards.

By far, the most DEADLY thing in your house will be your microwave oven if you have one. If it has a conventional mains transformer, the output voltage to drive the magnetron will be about 2kV with at least a few hundred milliamps behind it. Those have plenty of voltage to overcome your skin resistance, and easily more than enough current to stop you cold once you do make contact. People like to "salvage" the transformers out of old scrap microwave ovens and tinker with them. Not a good idea. This is why we hear about people being maimed and killed making Lichtenberg figures in damp wood to either follow some dumb online trend, or turn a quick buck selling them. They are the perfect impedance match for your wall outlet to electrocute you. I have a few of these, along with a scary 3000V/1500W lab power supply I have yet to power up. I don't have suitable SHV (safe high voltage) connectors nor the correct interlocking to actually test it out. And by test, I mean have HV probes and other automated measuring devices so I can be far away using some suitably non-conductive switching mechanism once it powers up.

 

[Cars-N-Cans]

Sorry to report a 12VDC lead acid battery in a Toyota Camry can kill you deader than a door nail. It's NEVER the voltage it's always the amperage.

That little welding example above gives an idea what a little CAR battery can do. Think of 4 G-31 batteries. I've walked up on 2 different people
on the ground, behind jumping heavy equipment. Both times they were out cold and one was dead. No pulse! They rescued the guy and he made
a complete recovery. I had to inspect several battery explosions in one company over a 19 year period. Every time it was a procedural issue. Like smelling
heavy battery fumes and STILL attaching cables to jump equipment. BOOM!

I suspect with those the batteries were in series. When you wire a bunch of them together to run a large motor, then the voltages start getting dangerous. Same with electric cars. They are equivalent to the electrical service entrance on a large building given they can supply substantial voltage and current when the s*** hits the fan.

In regards to 4 12V batteries, that is getting into the region where it could pose a moderate hazard under normal conditions, and potentially a significant one in wet or saline locations like out in the rain or loading road salt. Anything that lowers the resistance of your skin can be a hazard. Care and rubber gloves should be used when handing those, but its not 12V. Its the 48V (or >50V when fully charged) with the ability to supply current. Its not current or voltage that kills. Its voltage with sources that can source or sink enough current to get to the threshold of what is lethal. With cars, they use 12V generally for the reason that its high enough to be useful, low enough to be safe.

 

[Cars-N-Cans]

If we want a good mechanical analogy for danger vs. voltage, the following can help frame it:

12V = Bicycle tire
48V = Car tire
120/240V = Semi/Tractor-trailer truck tire
2000V = Passenger jumbo-jet or military cargo aircraft tire.

The current in this case and coming into contact with them is equivalent to overinflating them until they pop. The bike tire will make a loud pop. The car tire will make a loud bang and probably send the rim flying, potentially breaking some bones, and potentially killing you if it hits you in the head. The truck tire will rip all your cloths off, and potentially break your neck as well. The odds are significantly in its favor of killing you. The jumbo-jet tire will launch large sections of rubber at you weighing more than you do, killing you instantly and likely leaving you in pieces. The shockwave alone may be deadly. While the size (voltage) by itself may seem daunting, its the combination of energy stored as pressure (i.e. potential for current flow) along with it that really does the damage.

 

[raindance]

This all makes me chuckle. Many years ago a friend installed a high powered amp in his car and was complaining that it wasn't even as loud as the standard head units 6x6 watts. I investigated and he'd run 18awg cable all the way to the trunk to run it. I got him to upgrade to something like 2 or 4 awg, can't recall, but that got him the volume he wanted (although he grumbled when he installed the wire - I think he thought I was insane).

 

[OldHvyMec]

Did you read the post. Your assumption are deadly.

68 years old, Retired heavy duty master mechanic. DC is deadly. People sweat a LOT that WORK. Every time people assume what they have not personally experienced
and read in a book is some how applicable in the REAL world of any mechanic. That is assuming they are paying attention or are learning the hard way from a hospital
bed.

I just explained TWO people were on the ground. I had to figure out why. You seem to think ark welding with a battery doesn't = DEATH. Please stay away from
me.

The most deadly thing in your house is underestimating 120VAC. People in the US seldom die from high voltage. They repeat the most deadly mistake made over and
over. They don't disconnect, lock out/tag out or take precautions if they don't. 120vac kills more people than anything else by far. You don't need to be messing with a micro wave either. 100s of hair dryers have been dropped in water. Remember we have 7.9 billion people on earth. At least 3 billion are complete idiots right out of the
gate.

I worked in the field around a lot of cabling sometimes. I hated it. People are really stupid. 440VAC from a 400KV gen set will blow a person apart. Elbows, knees,
feet, explode. That is the reason you live not die. The person is usually blown away from high voltage/amperage. DC is not so nice in heavy equipment. 120VAC
is the same way. Getting trapped and zapped is a bad too. USE THE BACK OF YOUR HAND ONLY!!! Your hands contract when it's DC you can't let go..

I've seen several wrenches with chunks missing behind shorting a main + battery lead.

I tell everyone with any brains. Lock out and tag the circuit if you are forgetful or working with others . Test all circuits before working on them UNLESS
you are roughing in a home or a piece of equipment. NEVER trust anyone. It's in the book for a reason. I wrote it in a few manuals I had to update.
You trust equipment and safe practices never the work of some 30 year old going through his 8th breakup that month.

You are as good as the information you have access to and put into practice. Safe advice has no short cuts..

I suppose I could get all techy with my fancy cut and past abilities. I'm trying to share the reality of people that were harmed by people that thought the
safety book applies AFTER you start the job, not before.

With great respect and ALL of my fingers and toes.. LOL

 

[Cars-N-Cans]

Did you read the post. Your assumption are deadly.

Please brush up on how electric shocks actually work. I have both practical experience as well as being a degreed professional. I'm not just "shooting the breeze," here. You are spreading genuine misinformation. 12V is unlikely to be deadly. This doesn't mean impossible. But very unlikely. They chose that voltage for a reason. The differentiator here is, again, voltage, and forklift batteries are NOT car batteries. They are equivalent to multiple car batteries in SERIES because its the sole power source for the machine, not there to just crank an engine over. Huge, massive difference between 12V, and 36V or 48V. Those are getting to the point where it could cause cardiac arrest under certain conditions.

Question: If you take a box of fresh alkaline 9V batteries, and make a string 100 of them by clicking them together so they are all in series, and touch one end with one hand, and the other end with the other, do you think it will hurt you? Would you be confident it would be harmless since its just volts? Hint: 9V batteries have short-circuit currents of about one amp.

 

[Cars-N-Cans]

And please don't actually try this. I know the answer, as do many others who have formal training.

Edit: And for context, I used to work as a consulting engineer, and one of my tasks was dealing with building and electrical safety code. I have more than just a layman's knowledge of it. Saying or implying the volts are harmless is the most irresponsible thing you could say. Its the voltage of the source along with its ability to supply current that prove fatal. Knowing what voltage can be lethal when is important, and having people get squeamish with a car battery while throwing caution into the wind with a 27" CRT TV they are trying to "restore" or a trash-picked microwave oven to make a Jacobs ladder can and has often been fatal. Go and read some relevant sources on the topic before posting any more.

And to correct your original statement: It's NEVER the voltage it's always the amperage. Its never voltage or current, its the combination of voltage and current that kill. Knowing how much, when, and what voltage sources are dangerous is essential. You'd be surprised what can be dangerous, like multi-kW car amplifiers or home audio amplifiers that are >1kW of output. The power supply rail voltages are not trivial, and even then you can have over 100V from rail-to-rail in something like an AV receiver from your local big-box store.

 

[Cars-N-Cans]

And its a shame that otherwise a relatively light-hearted and interesting thread had to go down this road, but if everything is dangerous, than nothing is. To be safe, you need to understand the underlying mechanism of electric shock. Even using painful alligator clips on a meter I cannot get myself to read much below one megaohm. Skin is fairly resistive, even the dermis underneath the outer epidermis. Much like our electronics, since we rely on electric signals to live, the body has some modest defenses against potential "EMI". I can lick my fingers, sweat all over the place, and grab a fully-charged 12V car battery and nothing will happen. There's too much resistance. I work on cars often, I have done this 100's of times, and the odds are much, much, greater of being killed by lightning than dying from the car battery. Now, what was scary was grabbing a metal ball-chain pull string on a light when I was bare-foot. It was live, and it was very hard to let go. While that was not my most painful shock, it was damn well near the closest. I can appreciate you caring about safety, but to be genuinely safe, you have to correctly identify the dangers. In your old gasser, the battery is not one of them. The ignition system is potentially a maybe if it the right time relative to the heart repolarizing. But something like a battery charger that has suffered an insulation breakdown in its transformer and is passing 120V/240V to the terminals that would normally be at 48V on a job site, that most certainly is. And the same can be said for cellphone chargers. Those little piss-ant flyback transformers don't buy you much. Let some Chinese company make one out of the same wire they use for Bluetooth speakers without redundant insulation and separation and you have the nastiest surprise waiting for you if you decide to charge your phone on the hopper. A great instance was my company sourcing THOUSANDS of little square USB bricks of death and having them stamped with the company logo to give out as "presents." Be killed on a rig at sea? Nope. Die in a helicopter crash on the way back? Nah. Charge your phone in the kitchen? Good bye...

Here is a similar USB charger that was built the same way (I took mine apart and was genuinely mortified by its construction):

 

[Martin Takamine]

Hello,

I have a PDX m12 amplifier and a alpine type x subwoofer that was used for a car audio awhile back. Both items are discontinued so awhile ago.

Goal is to have a couple speakers hooked up to PC but any chance I can hook up the amp sub combo at the same time? Sounds like it would be impractical or not worth. But if there was a way to do it wouldn't mine learning. I do not know anything but i did watch a video on DACs, so i got that part down.

Someone else stated they are doing the setup below. Would this apply the same way? Thanks

"
I just ordered up a Topping DX3Pro+ DAC/Amp and a Topping PA3s amplifier. As I understand it, I'll be able to connect as follows:

PC USB --> DX3Pro+ --> RCA in on SE8 Sub --> RCA out on SE8 Sub --> PA3s RCA in

All I should have to do is gain match the amp and the sub, set crossover and HPF on the sub and I'll have variable volume control at the DX3Pro+, while cutting sub 60Hz frequencies to the B1+ speakers."

The juice isn't worth the squeeze.

 

[OldHvyMec]

Cars-N-Cans​

I appreciate that you think what ever it is you know you know. I'll say this politely one more time. A little battery out of MY Toyota "CAN" kill you.
The fact that 35,000 plus people die every year in cars on US roadways that have more protection than a F-15 Eagle is something to pay attention to, TOO!
A lot of cars burn to the ground because of ELECTRICAL, not FUEL. Seldom in a full blown fires does the fuel tank on a car become involved. Tractor trailer and
the like are different.

Aluminum and diesel fuel burn HOT. Gasoline has a low flash point. If the two mix you have a HOT fast moving fire with great potential.
Now add Tesla cells into the mix. What you read in the book is nothin like real life when lithium blows up. It is EXPLOSIVE.
Add diesel, gas, aluminum, neoprene, vinyl, PVC, ABS, memory foam, and a few bodies it really make for a smell you will never forget.
ALL because of a 12.8-14.2VDC system in a CAR failed.

There is a reason to write a safety manual. Something had to happen. You read the BOOK after the fact about safety or before? Do you apply the safety before
or after someone is hurt?

I've been reading about people using lithium batteries indoors without a safety box. How many NUTS have died behind lithium fires? There is a reason for
lithium power to be encased and COOLED. If you have ever been around a mishap involving lithium batteries you would know the structures involved have
to come down because of lithium contamination and the stench. It will not go away. They usually encase the cells to protect against fragmentation and add
fans. I read now people use these batteries in a domicile and remove the ballistic enclosure so the fan doesn't come on.

They surmised that because their home didn't burn down YET, the safety precautions about explosions didn't pertain to them.. After all it's only 12VDC.

DC is a killer. AC is a killer. Elephants if you piss them off can be killers. No matter how you get there, DEATH is pretty final on this earth.
No More Stereo for sure. LOL

 

[Doodski]

You'd be surprised what can be dangerous, like multi-kW car amplifiers or home audio amplifiers that are >1kW of output. The power supply rail voltages are not trivial, and even then you can have over 100V from rail-to-rail in something like an AV receiver from your local big-box store.

I took 2- 20,000 micro Farad capacitors at ~+/-65VDC across the forearm and my arm muscles twitched and I smacked myself right across the nose. Made a big smack sound and apparently my workmate was looking at me at the exact time it occurred. Scared the living crap outta me because that was a close one.