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View Full Version : How to tune an amplifier.


KuruptGTA
08-13-2006, 11:01 AM
This is a copy and paste until I can write my own. ;)

First things first, after physically completing the installation, make sure your amplifier is powered up properly. It needs to turn off and on with the key. The power light should turn off when you take the key out of the ignition. Test this out a couple of times to make sure.

Now, go to the front of the car, and turn on the stereo. Put in your favorite CD (not a burned CD, but one that was professionally mastered and recorded), and tune in to your favorite track. I recommend using a very dynamic type of music, with many types of musical variations within the CD.

Before You Start to Make Any Detailed Adjustments

As for the physical adjustments of the amplifier(s) you are tuning, first make sure the gain(s) are turned all the way down. That is, the knob turned all the way down to the left. Next, set your appropriate crossovers. Crossovers basically tell the amplifier which frequencies to allow the speakers to reproduce. High pass crossovers are for interior speakers, and low pass crossovers are for subwoofers. Now, roughly adjust the crossover frequencies, setting the high pass crossover between 90 -150hz for the interior speakers, and the low pass crossover between 90-150hz for the subwoofers. Hertz (hz) are simply a unit of measurement used to measure a particular frequency. If you set the low pass crossover at 100hz, that means that frequencies above 100hz will start to roll off ( not be played at full output volume)at the predetermined slope of your amplifiers crossover, be it 12db, 18db, or 24db. (These are the most common crossover slopes, your amplifier may vary) All frequencies below 100hz, however, will be allowed to play through the particular output (speaker)

By setting a high pass crossover at 100hz for example, this means that any frequencies below 100hz will start to roll off ( not be played at full output volume)at the predetermined slope of your amplifiers crossover, be it 12db, 18db, or 24db. (These are the most common crossover slopes, your amplifier may vary)
All frequencies above 100hz, however, will be allowed to play through that particular output channel (speaker).

Adjusting an Amplifier for Your Interior Speakers

If you are adding an amplifier for your interior speakers as well as a subwoofer amplifier, you must first start the tuning process with this amplifier before adjusting your subwoofer amplifier, which will be covered later in the tuning process.

Adjusting a four channel amplifier is very detail oriented. Again, with your gain(s) turned all the way down, begin to turn the volume of your source unit up until you reach its maximum volume.
This will vary depending on the source unit you are using. If it is an aftermarket unit, the volume scale usually operates between zero and a certain number, say 62. If this is the case, you would turn the volume back down to about 59. Have your bass settings set completely flat as well. You should be able to independently adjust your subwoofer. Make sure the preliminary crossovers have been set (high pass) and the frequency roughly adjusted (90 -150hz) before you proceed.

Front Speakers First

Now, slowly begin adjusting the gains up (clockwise), blending in the front speakers first.
Begin increasing the front gain until you detect the slightest bit of audible distortion in your front speakers. Take careful precaution to ensure that absolutely no distortion is present in your front speakers before proceeding. Distortion is when your speakers begin sounding muffled or crackled, if that makes any sense. Distortion will blow your speakers, and blown speakers are NOT covered by warranty. If any distortion is audible at any point in the tuning process, back the gain down (counter-clockwise) about 1/16th of a turn to the left, or until the distortion becomes inaudible again.

Moving to the Rear

Slowly begin to blend in the rear speakers by increasing the gain (turning the knob clockwise) until they become audible. You don’t want them to overpower your front speakers, as you are trying to develop a soundstage in the front of your vehicle, aren’t you? Blend them in until you can detect their presence clearly from the front seats, but your ears aren’t drawn to the rear of the vehicle. This allows your soundstage to become more present, which is the primary goal of the entire installation, right? You want your rear speakers to be a part of the equation without a doubt, but not the focal point. Get it? When you go to a concert, where does the band play? Not behind you.

You might make minor adjustments here and there, but for the most part, you can leave this amplifier alone unless you change any other components in your system. At that time, it will be necessary to readjust your settings to accommodate your new products.

Make it go boom.

Now is the time, if you are adding multiple amplifiers, to tune your subwoofer amplifier. Remember to roughly set your low pass crossover around 90-150hz. For example, if you set your low pass crossover to 100hz, that means that all frequencies above 100hz will not be sent to that particular output channel (speaker).

If you also amplified your interior speakers, it is important to overlap your crossover points to ensure that there no significant gaps in the frequency response of your audio system. For example, if you set your high pass crossover for your interior speakers at 110hz, you need to set your low pass filter for your subwoofer at a minimum of 110hz, but not more than 120hz to keep an overall tonal balance in your system

Again, with your gain(s) turned all the way down, begin to turn the volume of your source unit up until you reach the point where the interior speakers are distorting ever so slightly.

Now, back down the volume until the distortion disappears and stop there. Head back to the trunk and slowly begin adjusting the gain(s) of the amplifier until you are content with the amount of bass being produced by the subwoofer without any audible distortion of the woofer. Also, make sure the clipping light on the amplifier is not illuminating. If it is, back the gain(s) down until the light ceases to flash. Now, as you adjust the volume of the head unit, the bass will adjust proportionately with the rest of your music.



EDIT:

See the original here:http://forums.bimmerforums.com/forum/showthread.php?t=281419

Cam-aro
08-20-2006, 09:35 PM
Your a little off on a few things. If it wasn't so late we could work this out bud and get ya set straight on everything. I'll send you PM or something in the morning, let's get the best info possible out to our guys, aight!?

KuruptGTA
08-21-2006, 10:40 AM
Your a little off on a few things. If it wasn't so late we could work this out bud and get ya set straight on everything. I'll send you PM or something in the morning, let's get the best info possible out to our guys, aight!?

First of all, it's a copy and paste (with BMW removed) as posted at the top. I edited it to contain the link to the board so you can go bitch at them.

Second, I'm not your "bud," mmmkay?

Third, you're off on a little more than a few things. http://smiliesftw.com/x/Firepit.gif

MrDude_1
08-21-2006, 10:47 AM
oooh drama! :kiki:

KuruptGTA
08-21-2006, 10:49 AM
:wavey:, finally!

fredo92
08-21-2006, 11:03 AM
Your a little off on a few things. If it wasn't so late we could work this out bud and get ya set straight on everything. I'll send you PM or something in the morning, let's get the best info possible out to our guys, aight!?


Ah, I see God's gift to all things 3rdgen has arrived! :kiki:

KuruptGTA
08-21-2006, 11:08 AM
:lmao:

He is from TGO, and as such, must be revered...:eek3:

sc1twntrbo
09-02-2006, 04:34 PM
so i need you to drive to dallas and tune my stereo thanks

KuruptGTA
09-03-2006, 12:42 AM
...drive to phoenix and I'll do it. :esquint:

sc1twntrbo
09-04-2006, 07:24 PM
...drive to phoenix and I'll do it. :esquint:

i dont trust the ta that much

02gsxr600
07-18-2007, 01:58 AM
Sorry, but as a USAC world finalist I can tell you that's a beginner's 101...

Distortion can NOT be measured by ear, there are many factors which far exceed the technicalities of this thread...

A speaker can be destroyed by numerous factors, the word distortion is used far too freely. In a sense, a sound wave is no different than the A/C current in your home electrical system, an RF wave from your home network, etc... The term Hz refers to the number of times a frequency alternates per second (alternating current). Therefore, 60hz would mean the speaker would travel in/out 60 times a second. When an audio source, whether from the HU or the amp exceeds its maximum output you get what is called "clipping". This is by far the easiest way to blow a speaker of any kind - So by starting off your "cut and paste" by saying to start by turning your HU's volume all the way up is wayyy off! Just because the HU can go up to 80 for example, doesn't mean that's its loudest point. For example, Eclipse HU's a few years ago (can't speak for new products) had a subwoofer output control that would allow you to go up to +16, however +12 was a 0db gain, therefore going to +16 would give you a +4db gain and add clipping before the signal even reached the amplifier!!

A GAIN CONTROL IS NOT A VOLUME KNOB...

Gain matching is a more correct term, meaning you are matching your HU's maximum output without clipping, with the amplifier's maximum output without clipping. This is much easier to do by ear with front/rear speakers, but like I said you can't go by ear. When gain matching a subwoofer, 99.9% of people can NOT hear the distortion because the bass drowns it out! You may hear the distortion and turn down the gain and think it's ok, but you're really just fooling yourself. The only real way to truly tune an amp is with an oscilliscope.

Another myth is that too much power ruins a speaker, when infact under-powering a speaker is what does the most damage! If I were on a budget - I'd spend the majority of my money on a GOOD amplifier first, and buy a cheap sub! Even if the amp's output is 2,000W and the sub is rated at 300W! You can always turn a gain down if your sub is bottoming out, but you can't turn the gain up to compensate for the power loss by not buying a good amp without clipping.

I guess the final word of the night (getting late!) would be that throwing out numbers like 100Hz for a low-pass is not a good idea! You could buy the best amp and sub on the market and throw it in a pre-fab box, and I'll spend $100 at Walmart and sound better than you anyday. The enclosure you put your driver in is by far the most important thing! There is no such thing as one size fits all when it comes to speaker enclosures - period. You must first decide what your goal is (SQ, SQL, SPL) then determine what frequency range you would like to cover and build the box around those spec's. There are many formula's and programs out there for those who don't know how to design this part. The reason I say not to throw out a random number like 100Hz is because you can easily damage a driver if you don't know what you're doing. A ported box for example is tuned by the port area and port length, the smaller or longer the port, the higher (and safer in some instances) the frequency response. If you have a very large port primarily used for SPL, your tuning frequency is much higher - if you were to play music at a lower frequency continuously you'd bottom out the sub and end up destroying the voice coil. This is because there is no air pressure "resistance" from the port and the driver is moving slower and not creating the accoustical suspension it needs allowing the driver to move farther than it's Xmax.

Anyways, it's 4AM and I'm going to bed - hope this makes sense, lol I'm starting to fall asleep at my computer! If anyone has questions feel free to ask! Maybe I'll write up some tutorials on sound theory if anyone wants them...

TMoNeE
07-18-2007, 10:43 AM
lol :owned: with his first post, you suck kurupt :P

02gsxr600
07-18-2007, 09:09 PM
oops, double post