Subs getting warm

[osamio]

If you want to check the impedance of the speakers, remove any wires, and put the + lead of the DMM on the + speaker terminal of the voice coil you are checking. Put the - lead on the - terminal. And put the voltmeter in Ohm mode, often times it will be a little Omega symbol, (upside down horseshoe) a 2ohm Voice coil should read just under or just above 2 ohms.

I think you were wondering how to set your gains with a DMM, the long ass process is here:

How to set your amplifier gain with a DMM:

There are a lot of tutorials on the internet talking about setting your amplifier gain using a DMM (Digital Multi-Meter). Here I will clean up the process as simply (but accurate) as possible.

Necessary Tools/Skills

1. A volt-meter or DMM with standard test leads.

2. Ability to do 6th grade math.

3. Screwdrivers and/or Allen Wrenches (to make amplifier connections).

4. A CD with test tones - 50Hz for subs, 1000Hz for speakers.

Start by making a quick list of your equipment and their output voltage (head unit, LOC, processor, crossover, eq, etc.) and input sensitivity (amplifier(s)).

Next, list your power output ratings (actual RMS power)

Then, list your speaker/subwoofer impedance(s).

You need to know how your speakers/subs are wired - what the final impedance is going to be at the speaker terminals. If you can't figure out these numbers, you shouldn't be installing amplifiers. Pay someone who does and save yourself the damaged equipment.

Those numbers are VERY important as it is needed for the calculations below:

We are going to use the equation solving for Voltage using Power and Resistance.

Voltage = SQRT(Power x Resistance)

Example:

I have a single subwoofer with 4 ohm DVC coils. I'll wire the coils in parallel for a 2 ohm load. The sub is rated for 500W RMS.

I have a single amplifier rated 500W x1 at 2 ohms. I want all of that power available (knowing that power will only happen for small durations).

Volts = SQRT (500W x 2 ohms)

Volts = SQRT (1000)

Volts = 31.6VAC

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Determine the maximum head unit voltage you want to use as follows:

1. if you have a factory head unit and factory speakers and are using a LOC for your sub amp, use the highest volume level you do for music (without distortion to the speakers).

2. if you have an aftermarket head unit powering factory or aftermarket speakers and are using the HU preouts for your sub amp, use the highest volume level you do for music (without distortion to the speakers).

3. if you have a factory or aftermarket head unit feeding a signal to amplifiers for speakers and subs, you need to verify the maximum unclipped, non-distorted output - or just use a 75% volume setting if you are unsure if your headunit is capable of 100% unclipped volume. You can verify this with an oscilloscope.

When setting a subwoofer amp - if your head unit is powering speakers, you really want to disconnect them or use a high pass crossover on them. however, this may not be realistic for you. if not, then your max volume setting may not be possible without distorting your speakers. don't distort your speakers for this exercise. use whatever volume you can that doesn't distort your speakers. This is not the ideal situation, to do it right you should put high-pass crossovers on speakers when you have a sub.

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Once you have the head unit max volume determined, and the test tone CD playing on repeat. Set the EQ to flat, turn off processing. Make sure the fader is centered, balance is centered, sub level controls are maximum (sub level is just attenuation anyway).

You can go back to your amplifier.

Disconnect any speakers/subs not associated with the channels being adjusted. Set the gain to minimum. Turn off any bass boost. With the DMM set to VAC (Volts AC), touch the DMM positive leads on the speaker outputs. Slowly increase the gain until the DMM reads the voltage determined above.

While you're increasing the gain - LISTEN TO YOUR SPEAKERS/SUBS!!! Listen for any distortion - popping, scratching, noises that go away when you turn the volume back down.

You can use resistors to load the amplifier so you get a more accurate reading (like in the eD video), but the resistor load bank must have a power rating greater than the output power expected. Most of you reading this won't have a load bank on hand, especially for loads over 500W. Don't worry. You should be able to leave the speakers/subs connected - you're listening for clipping and distortion anyway.

Once you have set the gain on all of the channels separately, all of the amps separately. Hook up everything as it should be - all speakers and subs.

Now listen to your system with music. Listen for balance between all of the speakers and subs. If you desire a more balanced sound (i.e. subs overpower speakers) you TURN DOWN GAIN on the loudest speaker/sub. DO NOT INCREASE GAIN past your set points determined above. Most head units have sub level controls, fader, etc. that allow you to attenuate the signal from your HU.

Now you can start introducing EQ, boosts, etc. Note that any bass boost more than 6dB can result in clipping or damage. You've already set the amp gain as high as it should be. Once you get your EQ and boosts set, you should check your gain setting once again. Excessive bass boost settings will cause clipping.

If you get noises then reduce the gain at the point where there are no noises or popping as it may be an indication of amplifier clipping, or speaker/sub distortion.

If it's not loud enough - buy more or larger speakers/subs, more or larger amps, and start over. Don't force your equipment to be louder than it can, or you'll destroy it.

Credit for this goes to Alex K: http://www.stevemeadedesigns.com/board/user/30176-alex-k/

[GoHoMeUcRyBaBy]

So setting my amp to the given frequencys and stuff really helped. They still get kinda warm, but its probably because i live in Az and its starting to get warmer . I will be upgrading the sub wires soon so maybe that will help out to a little.

[Guest]

havent read through the thread, but if you are clipping, your woofers more than likely WILL get warm or hot. there is a small percent chance that you can be overpowering them with clean power and they are getting warm, but that does not apply in your case.

[GoHoMeUcRyBaBy]

havent read through the thread, but if you are clipping, your woofers more than likely WILL get warm or hot. there is a small percent chance that you can be overpowering them with clean power and they are getting warm, but that does not apply in your case.

Well i have 2 dual 2 ohm p3's wired down to 2 ohms running of a kenwood class D amp. I play mostly rap and some of decafs stuff.

[Guest]

havent read through the thread, but if you are clipping, your woofers more than likely WILL get warm or hot. there is a small percent chance that you can be overpowering them with clean power and they are getting warm, but that does not apply in your case.

Well i have 2 dual 2 ohm p3's wired down to 2 ohms running of a kenwood class D amp. I play mostly rap and some of decafs stuff.

i read the first post. you are underpowering them. and if they get warm, you are clipping. you are expecting that little kenwood amp to output way more power than it actually was designed for. get a new amp or turn the gains and bassboost down. and if you do that correctly, they will NOT get warm anymore.

[GoHoMeUcRyBaBy]

havent read through the thread, but if you are clipping, your woofers more than likely WILL get warm or hot. there is a small percent chance that you can be overpowering them with clean power and they are getting warm, but that does not apply in your case.

Well i have 2 dual 2 ohm p3's wired down to 2 ohms running of a kenwood class D amp. I play mostly rap and some of decafs stuff.

i read the first post. you are underpowering them. and if they get warm, you are clipping. you are expecting that little kenwood amp to output way more power than it actually was designed for. get a new amp or turn the gains and bassboost down. and if you do that correctly, they will NOT get warm anymore.

so if i got a 1500 rms constant power amp that would be to much?