best way to adjust amp without meter?
02-22-2013, 11:29 AM
#1
best way to adjust amp without meter? I have a front stage amp, along with a subwoofer amp (rear speakers powered by headunit).
Should I be adjusting the front amp gain based on the same volume of rear speakers (and adjust the fader to compensate front stage vs rear fill)? Or should the front gain be adjusted so it is louder than rear even with the fader in the center position?
Should I be adjusting the front amp gain based on the same volume of rear speakers (and adjust the fader to compensate front stage vs rear fill)? Or should the front gain be adjusted so it is louder than rear even with the fader in the center position?
02-22-2013, 07:06 PM
#2
From what I've researched, you dont want to think of your gain as a volume control. Think of it instead as a level of the amps that you're MATCHING to the RCA Outputs of your headunit.
Here are some steps I found prior to tuning my setup. You'll have to scour the web for some of the test tunes (I used 40hz for subs, 1000hz for mids, 5000hz for tweets). I had started to tune my setup using this method (only got as far as the mids) but at 3/4 full volume on the headunit I couldnt get my headunit to clip (I have a Pioneer DEH-80PRS which is supposed to be pretty good so I wasnt surprised that I didnt clip at that level). I ended up going the multimeter route since I needed to buy one to track down a drain anyways and just tuned that route. One thing i will say about tuning by ear though....have some ear plugs handy. If your headunit gets anywhere near as loud as mine was without clipping and you're taking it up till it clips, your ears will not be liking you. Anyhow, here are the steps I was going to use prior to the multimeter method:
1 - Turn off all of your headunit's processing (crossovers, EQ, etc) and if you have an Alpine, set the bass level to the full +15.
2 - Turn your amp's gain and your headunit's volume all the way down (counterclockwise).
3 - Lets do the mids/highs first. Put on a test tone near the center of your amp and speaker's bandwidth. I like to use 1khz personally
4 - Slowly turn up the headunit's volume while listening for the signal to clip. When you find this volume, turn it down a few notches so it's clean and it's a volume setting that's easy for you to remember (my headunit clips at 33, but I use 30 for setting the gains, just for an example). In case you don't know already, here are some tones to help you get an idea of what clipping sounds like:
1khz clean : http://www.thesuicidaleggroll.com/hosting/1000sine.mp3
1khz clipped: http://www.thesuicidaleggroll.com/ho...1000square.mp3
5 - When you find the maximum undistorted volume of your headunit, it's time to start turning up the amp's gain. You're listening for the same thing here, as soon as it starts to clip you want to back off of the gain slightly to make sure it's clean again. If your headunit has powerful preouts and your amp has a small input range, there's a chance that it might clip as soon as you start to turn up the gain. This is perfectly fine, just leave the gain at the minimum setting.
6 - If you're at this step then your gain is set, all you have to do is remember the headunit's volume at which you did the test and you're set. Remember that you should not turn your volume higher than this setting unless what you're playing is recorded at a very low level, or else you risk clipping. Also remember that any EQing that you do will change the point of clipping, if you have anything boosted more than a dB or two then you should try to stay a good bit below this maximum volume found in step 4 or you risk clipping at those boosted frequencies. Also remember to re-wire your speakers back to normal.
7 - Time for the sub amp. Unfortunately clipping can be hard to hear at low frequencies, especially with the crappy subs out there these days that couldn't play an accurate note to save their life. The higher the frequency you play the easier it is to hear clipping, but if you're using a mono class-d amp then you'll most likely be limited on the upper end at ~300hz due to the amp's limited frequency response, or it might actually have an adjustable lowpass filter that can't be defeated which you'll have to watch out for. If your lowpass(es) can be turned off then do it, if they can't then just turn them to the highest frequency possible. Pick a test frequency that's at least an octave below your lowest lowpass filter, 100hz or above would be preferable, but sometimes it's not possible.
8 - At this point it's all the same as before, turn the headunit to the volume found in #4, and then go back to step #5
Furthermore, I know you asked for tuning without a meter but in case you decide to get a meter or if anyone else stumbles across this thread in a search for tuning with a meter here are the steps I found and followed on the web (using the same frequency test tunes I mentioned before). The math included is what I calculated for my particular amps so if yours differs make sure you calculate your own values and dont just go off of mine.
Step 1: Disconnect the positive speaker wire(s) from the positive terminal(s) on the amplifier.
Step 2: Turn off all EQ settings or set them to zero, such as Bass, Treble, Loudness, Bass Boost, Processing and EQ functions.
Step 3: Turn the input sensitivity (gain) to zero. For most amplifiers, this is counter clockwise (CCW) to the farthest point. Make sure the input voltage selector is on “Low” if the amplifier has one.
Step 4: Set the head unit volume to 3/4th of its maximum volume. Turn your radio dial to it's maximum volume and multiply that number by 0.75, this will get you 75% of your maximum volume.
Step 5: Now we must find the voltage that we need to set the gain to. Voltage = square root of watts x ohms. For example, a 500W RMS amplifier at 2 Ohms would configure like this: 500W RMS X 2 Ohms = 1000W. Now take the square root of 1000W and your voltage should be 31.62V if you’re running an amplifier with one gain control. Some amplifiers have 2 gain controls so treat it as two separate amplifiers. If the amplifier is 100W RMS by 4-channels for a total of 400 watts but has two gain controls, divide the total RMS by half and use that for your voltage calculations. (EX: Square Root of 200W RMS x 2 Ohms = Voltage for each gain control)
MMATS D3500.1 = 2700W RMS x 1 Ohms = 2700W
√(2700W) = 51.96V (Subs)
MMATS SQ4160 = 160W RMS x 4 Ohms = 640W
√(640W) = 25.29V (Midbass)
MMATS SQ4160 = 175W RMS x 2 Ohms = 350W
√(350W) = 18.70V (Tweeters)
Step 6: Make 100% sure the positive speaker wire(s) are disconnected from the amplifier. Once double checked, use sound files with a sine-wave test tone at 0dB level in the frequency range of 40Hz to 60Hz for a subwoofer amplifier or 1,000Hz for a midrange amplifier or 5,000Hz for tweeter amplifier. Set the head unit to repeat for continuous play of the test tone.
Step 7: Connect a digital multi meter set to AC Volts (200V Range) to the speaker outputs of the amplifier. The positive voltmeter lead will touch the positive speaker wire terminal and the negative lead will touch the negative speaker terminal. If everything is done correctly, a low voltage will be displayed on the voltmeter, usually 6V or below. If you get a high voltage right away, repeat steps 2 and 3. Slowly turn the input sensitivity (gain) up on the amplifier until the target voltage you calculated earlier is reached.
Step 8: Adjust every amplifier in your system using this method; each amplifier is now set to its maximum unclipped output level. Turn the volume on your head unit to zero and turn it off.
Step 9: Reconnect all the positive speaker wire(s) to their respective positive terminals. Double check all wiring and proceed to turn the headunit on. Remove the test tone CD and play a musical track that you are familiar with. Listen for any distortion in the form of buzzing, crackling, hissing, whomping, and various other noises that intrude on the instruments of your music.
Here are some steps I found prior to tuning my setup. You'll have to scour the web for some of the test tunes (I used 40hz for subs, 1000hz for mids, 5000hz for tweets). I had started to tune my setup using this method (only got as far as the mids) but at 3/4 full volume on the headunit I couldnt get my headunit to clip (I have a Pioneer DEH-80PRS which is supposed to be pretty good so I wasnt surprised that I didnt clip at that level). I ended up going the multimeter route since I needed to buy one to track down a drain anyways and just tuned that route. One thing i will say about tuning by ear though....have some ear plugs handy. If your headunit gets anywhere near as loud as mine was without clipping and you're taking it up till it clips, your ears will not be liking you. Anyhow, here are the steps I was going to use prior to the multimeter method:
1 - Turn off all of your headunit's processing (crossovers, EQ, etc) and if you have an Alpine, set the bass level to the full +15.
2 - Turn your amp's gain and your headunit's volume all the way down (counterclockwise).
3 - Lets do the mids/highs first. Put on a test tone near the center of your amp and speaker's bandwidth. I like to use 1khz personally
4 - Slowly turn up the headunit's volume while listening for the signal to clip. When you find this volume, turn it down a few notches so it's clean and it's a volume setting that's easy for you to remember (my headunit clips at 33, but I use 30 for setting the gains, just for an example). In case you don't know already, here are some tones to help you get an idea of what clipping sounds like:
1khz clean : http://www.thesuicidaleggroll.com/hosting/1000sine.mp3
1khz clipped: http://www.thesuicidaleggroll.com/ho...1000square.mp3
5 - When you find the maximum undistorted volume of your headunit, it's time to start turning up the amp's gain. You're listening for the same thing here, as soon as it starts to clip you want to back off of the gain slightly to make sure it's clean again. If your headunit has powerful preouts and your amp has a small input range, there's a chance that it might clip as soon as you start to turn up the gain. This is perfectly fine, just leave the gain at the minimum setting.
6 - If you're at this step then your gain is set, all you have to do is remember the headunit's volume at which you did the test and you're set. Remember that you should not turn your volume higher than this setting unless what you're playing is recorded at a very low level, or else you risk clipping. Also remember that any EQing that you do will change the point of clipping, if you have anything boosted more than a dB or two then you should try to stay a good bit below this maximum volume found in step 4 or you risk clipping at those boosted frequencies. Also remember to re-wire your speakers back to normal.
7 - Time for the sub amp. Unfortunately clipping can be hard to hear at low frequencies, especially with the crappy subs out there these days that couldn't play an accurate note to save their life. The higher the frequency you play the easier it is to hear clipping, but if you're using a mono class-d amp then you'll most likely be limited on the upper end at ~300hz due to the amp's limited frequency response, or it might actually have an adjustable lowpass filter that can't be defeated which you'll have to watch out for. If your lowpass(es) can be turned off then do it, if they can't then just turn them to the highest frequency possible. Pick a test frequency that's at least an octave below your lowest lowpass filter, 100hz or above would be preferable, but sometimes it's not possible.
8 - At this point it's all the same as before, turn the headunit to the volume found in #4, and then go back to step #5
Furthermore, I know you asked for tuning without a meter but in case you decide to get a meter or if anyone else stumbles across this thread in a search for tuning with a meter here are the steps I found and followed on the web (using the same frequency test tunes I mentioned before). The math included is what I calculated for my particular amps so if yours differs make sure you calculate your own values and dont just go off of mine.
Step 1: Disconnect the positive speaker wire(s) from the positive terminal(s) on the amplifier.
Step 2: Turn off all EQ settings or set them to zero, such as Bass, Treble, Loudness, Bass Boost, Processing and EQ functions.
Step 3: Turn the input sensitivity (gain) to zero. For most amplifiers, this is counter clockwise (CCW) to the farthest point. Make sure the input voltage selector is on “Low” if the amplifier has one.
Step 4: Set the head unit volume to 3/4th of its maximum volume. Turn your radio dial to it's maximum volume and multiply that number by 0.75, this will get you 75% of your maximum volume.
Step 5: Now we must find the voltage that we need to set the gain to. Voltage = square root of watts x ohms. For example, a 500W RMS amplifier at 2 Ohms would configure like this: 500W RMS X 2 Ohms = 1000W. Now take the square root of 1000W and your voltage should be 31.62V if you’re running an amplifier with one gain control. Some amplifiers have 2 gain controls so treat it as two separate amplifiers. If the amplifier is 100W RMS by 4-channels for a total of 400 watts but has two gain controls, divide the total RMS by half and use that for your voltage calculations. (EX: Square Root of 200W RMS x 2 Ohms = Voltage for each gain control)
MMATS D3500.1 = 2700W RMS x 1 Ohms = 2700W
√(2700W) = 51.96V (Subs)
MMATS SQ4160 = 160W RMS x 4 Ohms = 640W
√(640W) = 25.29V (Midbass)
MMATS SQ4160 = 175W RMS x 2 Ohms = 350W
√(350W) = 18.70V (Tweeters)
Step 6: Make 100% sure the positive speaker wire(s) are disconnected from the amplifier. Once double checked, use sound files with a sine-wave test tone at 0dB level in the frequency range of 40Hz to 60Hz for a subwoofer amplifier or 1,000Hz for a midrange amplifier or 5,000Hz for tweeter amplifier. Set the head unit to repeat for continuous play of the test tone.
Step 7: Connect a digital multi meter set to AC Volts (200V Range) to the speaker outputs of the amplifier. The positive voltmeter lead will touch the positive speaker wire terminal and the negative lead will touch the negative speaker terminal. If everything is done correctly, a low voltage will be displayed on the voltmeter, usually 6V or below. If you get a high voltage right away, repeat steps 2 and 3. Slowly turn the input sensitivity (gain) up on the amplifier until the target voltage you calculated earlier is reached.
Step 8: Adjust every amplifier in your system using this method; each amplifier is now set to its maximum unclipped output level. Turn the volume on your head unit to zero and turn it off.
Step 9: Reconnect all the positive speaker wire(s) to their respective positive terminals. Double check all wiring and proceed to turn the headunit on. Remove the test tone CD and play a musical track that you are familiar with. Listen for any distortion in the form of buzzing, crackling, hissing, whomping, and various other noises that intrude on the instruments of your music.
Last edited by dementia; 02-22-2013 at 07:17 PM.
02-22-2013, 08:55 PM
#3
Wow, thanks for so many details!
Reason I was using the gain like a volume **** is because while my new Kenwood HU has 4V preouts, my Kenwood amps seem to have very little volume when set to 4V. It wasn't until I put the gain slightly past 0.5V that the front amp volume was at least equal to the built-in amp output rear speakers. I'll try the test tones too.
Reason I was using the gain like a volume **** is because while my new Kenwood HU has 4V preouts, my Kenwood amps seem to have very little volume when set to 4V. It wasn't until I put the gain slightly past 0.5V that the front amp volume was at least equal to the built-in amp output rear speakers. I'll try the test tones too.
02-22-2013, 09:43 PM
#4
NP man, did a quick search and found the site that I got my test tones off of.
http://www.realmofexcursion.com/downloads.htm
You can burn it to a cd or put it on a flash drive if your head unit supports it. I loaded mine on my tablet and streamed it from there.
http://www.realmofexcursion.com/downloads.htm
You can burn it to a cd or put it on a flash drive if your head unit supports it. I loaded mine on my tablet and streamed it from there.
