rough idea for universal clipping indicator

[TheMonolith2001]

I had this idea actually while working on something else and wanted to write it down before I forgot it and get some opinions from you guys. It seems like it would work and be fairly accurate. Let me know if I am missing anything. It is 330 AM and I have been working a lot so hopefully I am not just overlooking something obvious. All the other solutions I have read involve poking around in your amp and/or are too complicated for your average person so it would be nice if this worked for those who don't have this feature built in. If it doesn't....well so be it. This is meant for a sub out by the way. I think the wider the frequency range/more complex the sound the less accurate this will be.

Things needed:

Standard gain setting materials

Good quality dash voltmeter, the faster reacting/more accurate the better

RCA splitter

RCA cable to chop into

Probably some wire

See where I'm going yet? If not here is the process. All numbers are made up numbers for this example and unfortunately probably won't end up this nice and round. If you have an adjustable volt meter you might be able to round it off though.

-Your gain is set at 50/60 with 0db test tone. Everything is clean.

-You measure the RCA output voltage with 0db tone at 50/60 and you get 5v. Probably a better idea to do it with the actual gauge. We just want a number here even if it isn't 100% dead on it just needs to read the same thing every time.

-Split the rca output on the head unit. One lead is going to your amp while the other is getting chopped and going into the voltmeter.

-You now have a voltmeter in your dash reading 5v at 50/60 volume on a 0db tone

-Start playing music and watch the gauge. You would be able to turn it up past 50/60 until you reach 5v on the gauge, anything above that and you are clipping. If the recording is actually at 0db or reaching it rather, this doesn't do anything for you. But for anything else you know what the limit is for that particular recording and you have effectively made a clipping indicator.

You could probably even get fancy and design a circuit that illuminates an LED at a set voltage but I wanted to see what was possible with off the shelf parts first. This has potential to be a lot more accurate however. I bet you could even get REALLY fancy and design a circuit that introduces some resistance when you go over your specified voltage. EX hit 5.5 and it limits it to 5 to make an idiot proof system. It would probably be hard to get it to react fast enough though.

Possible limitations:

Different frequencies may read different voltages even with 0db tones, if they are too far off from each other it screws up this whole idea. This is more a limitation of the volt meter than the head unit though unless the head units response isn't flat or something.

There is the possibility of introducing noise into the signal path. Again this probably depends on the quality of the voltmeter. I thought of a solution here too though as well as an alternate wiring method.

On my head unit I have a stereo sub out set to mono. I basically have two mono sub outs now. I could run one to my amp and one to the volt meter. Now I need even less parts.

[Broke_Audio_Addict]

http://damoreengineering.com/om-1.html

/thread

[TheMonolith2001]

YES! That is perfect! Exactly what I am talking about. Will get one of these when I have the extra cash. Looks so damn cool. I even know where I am going to put it!

I DO have a reason for the super late reply though. I have a temporary solution that should work just as well (completely analog and fast) but will not look NEARLY as cool. Wanted to see what you guys think! So here is the circuit:

Speaker + ---> Potentiometer -----> Zener Diode ------> LED -------> This is the confusing part, It seems like the SMD meter goes back into the ground instead of the Speaker -. I am assuming that would not be correct for this design. The SMD meter seems to have dedicated power for the LEDs and an IC setup while this circuit is actually using the amplifier output voltage to power the single LED while limiting it. I am thinking you will have to go back into speaker - with this one. I am not about to connect it until I find out for sure!

What is happening here is the power is going through the Potentiometer which you are basically using as a current limiter. You could use a trimmer too. Then it is going through a Zener Diode. (For those that don't know what a Zener Diode does it blocks current flow until a certain value is reached. Say I have a 12v Zener Diode, Well nothing can flow through it until I hit 12v or more.) Then it is flowing through the LED and back out. So you are tuning the pot to let through just enough voltage to open the Zener diode and illuminate the LED when you clip!

Yeah, so its one LED that illuminates when you hit a certain voltage, not NEARLY as cool looking. Also a VERY IMPORTANT detail here is you HAVE to start with the Pot/Trimmer at maximum cutoff and then slowly dial up or you WILL fry the LED. The Zener diode does nothing to limit voltage once it is open. I could make the circuit more complicated to prevent this, but I'm not exactly designing a retail product here I wouldn't want to anyway. The product you linked already exists and it doesn't seem like there is anything to improve upon except maybe doing the same thing in a different shape like a strip or something. (clipping/voltage indicator going up the A-Pillars/across the dash anyone?) It looks like the damore guys even already sell a DIY kit for if you want to build something like this! Nice!

If you guys want I can post some radioshack part numbers. One of the limitations I put on myself was that everything had to be available at the local radioshack. If your patient and want to order stuff online you could probably spend even less and make something a lot nicer looking. Radioshack pots have stupid long knobs for some reason. I can probably just cut it though. I put it together for about 8 bucks. This is JUST the circuit though and you don't want wires hanging all over the place so I am trying to find something that would make a nice enclosure for everything. The enclosures they sell at radioshack kind of suck. I used a 12v Zener diode and a 12v LED. Now you basically have to find the pot that matches your application. With the correct pot this should be good for amplifiers around 75-100 watts and up. The more resistance you can get in a pot the bigger amplifier you can use it on. For smaller amplifiers I would switch to a 5v Zener diode and LED. I experimented with making something like a gauge with an IC, but your basically just making a shitty looking knockoff of what you linked at this point and you aren't saving much money either especially after all the time you have to spend putting everything together. If you want more than a single LED, just buy the OM-1 the price is actually very fair!

I also built my own PAC LC1 from from radioshack parts. I can post that as well if you want. Although I think it is better built than the LC1, it doesn't save you any money. In fact I think I spent OVER 10 dollars MORE than you can get an LC1 for doing this. I was just bored one day and didn't want to wait for shipping You are basically soldering male and female rcas to a pot and running your audio signal through the pot. Very simple really although requires an entirely different pot than the one used in the above project because you need two ins and two outs. Its fun picking what knob you want though! http://www.radioshack.com/family/index.jsp?categoryId=2032274&numProdsPerPage=60 and that is just Radioshack!