sub problems

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DYohn

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Joined: April 22, 2003

Location: Arizona, United States

Posted: March 23, 2008 at 9:38 AM / IP Logged

audioman2007 wrote:

I can easily tell that my amp is not clipping. 1. My amp never gets hot. 2. I have the amp wired to 4 ohms. 3. I have the output on my headunit turned to negative 2 DBs. 4. I have very clean and tight bass. 5. I only get bass notes when I need bass notes. I never have bass notes blend into eachother. 6. I never have the bass cut in and out. Thats how I know my amp is not clipping.

Then you are probably 100% wrong. None of those things will tell you that your amp is clipping. Indeed, I would bet money it is.

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audioman2007

Copper - Posts: 580

Joined: February 20, 2007

Location: United States

Posted: March 23, 2008 at 9:40 AM / IP Logged

Then explane to me what I can do to see if it is. Ill go out right away and do what you said. I dont have any fancy devices to use though, so what else could i try?

audioman2007

Copper - Posts: 580

Joined: February 20, 2007

Location: United States

Posted: March 23, 2008 at 9:41 AM / IP Logged

Also, if you are running an amp at a constant clip, then what would break, the amp or subs? And how long would it take till it breaks?

audioman2007

Copper - Posts: 580

Joined: February 20, 2007

Location: United States

Posted: March 23, 2008 at 10:02 AM / IP Logged

I also just read one of the old closed topics about clipping. A clipped signal will heat up the subs voice coil. Ok, well how long would it take till the voice coil heats up? Also, is this something I could tell by simply touching the sub itself? I am asking this because I have had these subs for over 6 years now. I obviously ran them into clipping with my old amp and am obviously doing it now with this new amp which I have had for over a year. What I dont understand is that if I am clipping the amps and subs, then how comes my old amp lasted 5 years plus, and my subs are over 7 years old? I am in no means second guessing anyone on here. You all just have me worried and I want to make sure everything is alright with my system.

DYohn

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Joined: April 22, 2003

Location: Arizona, United States

Posted: March 23, 2008 at 10:05 AM / IP Logged

Clipping by itself will not "break" anything. A clipped signal can sound really flat and dull, and it can allow an amplifier to pass higher voltages than its rated power and potentially burn out a speaker voice coil. If you don't have an oscilloscope (the only meter that can show you that your signal is clipped) there is a test you can do by ear to listen to what a clipped signal sounds like. Do you know how to set your input gain using a test tone? The point where the tone changes is the onset of clipping. If you use this method to set your gain properly, and leave the bass boost off, then you can be sure your amp is not clipping. Have you done this?

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audioman2007

Copper - Posts: 580

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Location: United States

Posted: March 23, 2008 at 10:29 AM / IP Logged

Well the fact that I understand nothing of what you just said means that no I havent tried it before. If you can tell me what all I need supply wise and what I need to do step wise, I will do that today. Thank you.

DYohn

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Joined: April 22, 2003

Location: Arizona, United States

Posted: March 23, 2008 at 11:27 AM / IP Logged

audioman2007 wrote:

That's what I was afraid of. This is very basic installer-101 type stuff and should be well understood by anyone on this forum before they try to give advice to others.

The procedure has been explained here many times and will undoubtedly come up with a simple search for "setting gain" using the forum search function. But here's the basic procedure:

1) Record or obtain a CD with a test tone of about 60Hz (0db)

2) Disconnect your mains speakers. Set your subwoofer amplifier input gain at its lowest point. Set HU subwoofer output to max. Set all tone controls, loudness, bass boost, etc. to flat or off.

3) Play your test tone on repeat. Slowly turn up the HU volume until you can hear the tone change. Back if off slightly until the tone returns to its original 60Hz. This is the point at which your HU introduces a clipped signal. Note this volume and NEVER GO HIGHER THAN THIS when using your system. Some good quality heads will not clip. If you get the volume to max and cannot hear the tone change, set the volume to about 75% of max.

4) Wear hearing protection.

5) Go the the subwoofer amp and very slowly turn up the gain on the amp until you hear the tone change again. This is the point where the amp introduces clipping. Back it off until the tone is again 60Hz and leave it there. This is the gain setting that matches the max clean output from your HU.

6) Turn the HU volume down and stop the CD Reconnect the mains speakers and play some music. If the sub is too loud in relation to your mains, you may turn the gain DOWN a little to create the blend you need. NEVER turn it up past the clipping point.

The same procedure can be used to set the gain on your mains amps, only using a test tone in the mains range, say around 1500Hz..

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audiocableguy

Copper - Posts: 630

Joined: January 27, 2003

Location: Idaho, United States

Posted: March 23, 2008 at 1:24 PM / IP Logged

"This is very basic installer-101 type stuff and should be well understood by anyone on this forum before they try to give advice to others". Certain members here have a history of such inexperienced and borrowed advice.

audioman2007

Copper - Posts: 580

Joined: February 20, 2007

Location: United States

Posted: March 23, 2008 at 1:38 PM / IP Logged

Hey now. I take great offense to those comments. First off if I recall all advice on here recieved is recieved at your own risk. I give advice to the best of my knowledge, and am not saying at any point that I know EVERYTHING about this stuff. Even the smartest on here dont know everything either. I greatly appreciate you all helping me with this but I dont need those comments either. I learned something, and maybe there is something on here that you might need help with. I thought I knew about clipping but obviously I was wrong.

Anyways, I remember that my bass boost on my amp is for 60Hz and goes from 0 to 24DBs. Right now I have the gain at 1/2. I have the bass boost to about 14DBs. If I was to have my sub output to MAX, it would be at +6db's. Right now I have it at -2Dbs. Out of 40 volume I have it at 30 and dont go above that. I just have 1 more question. You said to get a test tone of 60Hz. Now with my bass boost being at 60Hz, does this mean that only 60Hz and around that will be clipped? If I was to back down the bass boost to 0, would the clip simply go away? What I am saying is that would I only have the clip signal during the bass boost frequencies which in this case would be 60?

stevdart

Platinum - Posts: 5,816

This member consistently provides reliable information

Joined: January 24, 2004

Location: Pennsylvania, United States

Posted: March 23, 2008 at 2:04 PM / IP Logged

Just stop, set your sights on getting the gain set as DYohn explained, and then go from there. Here are two sources for test tones that you can make yourself using your computer:

http://www.realmofexcursion.com/main.html

http://www.nch.com.au/tonegen/

Otherwise you are continuing on a line of questioning that is going around in circles. IIRC, I told you a couple months ago that when you refer to the gain dial "position" that you need to learn how to set gain properly. Criticisms such as offended you are appropriate for this forum, and indeed are offered without prejudice. Everyone here has been criticised and have summarily been offended, but we all get over it and learn from it. I've certainly had my share and know I'm not immune to it, but I nevertheless know that more often than not I learn from it.

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

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