trying to set gain for a mono amp powering 2 12's

[paintballer 10+ year member]

WHen i try to set the gain contrl on my amplifier for the subwoofers, how do i know when the subwoofer is starting to distort when i start increasing the gain. i heard it was very difficult to detect clipping in subwoofers. and i dont have any measuring tools that installers use. So how would i set the gain properly for my subwoofers amp. same goes for the 4 channel amp and the 4 speakers i have. How do i know whn i get clipping,?

Thanks guys for the help

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[azimuth 5,000+ posts]

WHen i try to set the gain contrl on my amplifier for the subwoofers, how do i know when the subwoofer is starting to distort when i start increasing the gain. i heard it was very difficult to detect clipping in subwoofers. and i dont have any measuring tools that installers use. So how would i set the gain properly for my subwoofers amp. same goes for the 4 channel amp and the 4 speakers i have. How do i know whn i get clipping,?
Thanks guys for the help

unless you run bandpass boxes, you can hear it.

 

[dawgdan 10+ year member]

You need to use a frequency that is easier to hear than sub frequencies. Like 300 Hz. If you're using a class D amp, use the highest it will allow (usually 250 Hz).

First, start by downloading 0db level test tones at http://www.realmofexcursion.com. Burn them onto a disc. Remember what track your planned gain-tuning frequency is on.

Set your amp gains to zero. Turn your crossover off. Disconnect your front speakers.

Turn your head unit on at zero volume. Set the bass level to your planned level of regular listening. For me, it's zero. If you have an Alpine, set it to +15 (it's how they set up their voltage from the factory).

With the volume still at zero, put the test tone disc in, and put it on the track for 300 Hz (or whatever frequency you plan on using). Set the track on repeat. Turn your head unit volume up to roughly 3/4 of maximum - this should be the absolute highest level you ever plan on listening.

Now go back to your amp and listen carefully to your subwoofers. SLOWLY turn the gain up on your sub amp. You'll eventually hear the subwoofer change how the frequency sounds. This is clipping. Now back down off your gains just a little bit so that it's playing at the max level without clipping.

Now this is the maximum level you'll want to listen to your subs. The same process works for your mids and highs as well. Just be careful because you are sending a full power 0db test tone to your speakers - abusing them much past the clipping point will kill speakers. Keep in mind to not turn it up past 3/4 volume, and that any sort of bass boost or EQ adjustments made AFTER you've set the gain are going to NOT allow you to turn it up as high. In other words, make all of your EQ adjustments before setting your gain.

 

[paintballer 10+ year member]

Thanks man. that heped a lot. Ill have to go to a parking lot after college, and do it, because i dont like people knowing i have a sound system in my apartment complex (haha, theft reasons).

There are a few things i need more clarification on though.

1.) i dont much about this stuff, so what exactly is a crossover. Does that term mean the same as a high or low pass filter. I have a mono class Amp (Alpine MRP-M650) and my subs are a prebuilt system ( MTX Dual 12" 1350W Subwoofers/Enclosure (TCE4512X2D)) and the subwoofer box w/subs has only one input terminal. THerefore i dont think my setup is bridged or anything. My deck is a Alpine CDA-9856 with ~7-+7 for the bass and the subwoofer volume on it goes from 0-15. I cant get the EQ to work on it anyways, so i guess that doesnt matter. I will not let for some reason. and i always have my BBE at setting 1. I always have my system at bass 2, treble 2, BBE 1. so when i do this gain setting, have it at those settings correct?, and dont go over those settings once its done correct? when doing the gain, should i put my sub volume at 15, so that that woiuld be the absolute sub volume after its all done. SOme guy before said the sub volume on the deck sends distored signals to the amp. is this true? and my volume goes up to 35. so i should have it on 26 correct? i havent touched anything yet since i got it installed, but i have looked at the dials and such.I think right now the subs start getting clipped at a volume of 22-23, because the subwoofer significantly lowers in pitch at this volume up. I didn't know what was going on at first, but now i realize its clipping, correct? i hope i didnt damage anything.

2.) you said to test a frequency of like 250. Rightn now the low pass filter frequency is set at 100. If i change it to 250 or whatever the highest it will allow me, when im done setting the gains, do i change back to the 100 mark... can i leave it at 100, or is it just harder to set the gains on that frequency.

3.) if i want to disconnect the speakers, what would i do. Just unplug the RCA cables right, since i wouldnt have to unscrew anything.

4.) when im doing the gain on my speakers, should i turn off the subwoofers via the option on the deck. would that be ok? wouldn't that make it easier to set the gains.

5.)Should i have bass boast off completely on the sub amp. on the 4 channel amp powering the speakers, whats a good high pass frequency to set it on and test it on.

THanks guys. i dont much about this stuff, so i appreciate the help. I want to be safe and dont wanna have anything get blown. Im just worried that i might have screwed something up already, everything sounds fine still..

THanks

 

[dawgdan 10+ year member]

1.) i dont much about this stuff, so what exactly is a crossover. Does that term mean the same as a high or low pass filter.

Oh boy, you have a long way to go. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif Yes, in basic form, a crossover is a filter. A crossover "tells" what frequencies to go to which speakers. Lots of crossover info is posted at http://www.bcae1.com.

My deck is a Alpine CDA-9856 with ~7-+7 for the bass and the subwoofer volume on it goes from 0-15. I cant get the EQ to work on it anyways, so i guess that doesnt matter. I will not let for some reason. and i always have my BBE at setting 1. I always have my system at bass 2, treble 2, BBE 1. so when i do this gain setting, have it at those settings correct?, and dont go over those settings once its done correct?

That's correct. What you want to do is establish an absolute maximum for your listening level. That doesn't mean listen at that maximum at all times - in fact, doing so will probably destroy your eardrums. But what we're trying to do is make a limit.

Keep in mind that your model doesn't have an EQ. Just bass, treble, sub, and BBE settings basically. I would recommend keeping BBE off - it can add some nasty distortion at high volumes.

when doing the gain, should i put my sub volume at 15, so that that woiuld be the absolute sub volume after its all done.

A maximum, yes. +15 on the Alpine decks sends a full-voltage signal through the RCA's to your amp.

SOme guy before said the sub volume on the deck sends distored signals to the amp. is this true? and my volume goes up to 35. so i should have it on 26 correct? i havent touched anything yet since i got it installed, but i have looked at the dials and such.I think right now the subs start getting clipped at a volume of 22-23, because the subwoofer significantly lowers in pitch at this volume up. I didn't know what was going on at first, but now i realize its clipping, correct? i hope i didnt damage anything.

The sub volume thing - it's not true. Set it at +15 for the gain setting. And yes, from memory, 26 on the new Alpines is where it starts to clip. Don't turn it up above this level. Your subs could possibly have been clipping, it's hard to tell over the internet. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

2.) you said to test a frequency of like 250. Rightn now the low pass filter frequency is set at 100. If i change it to 250 or whatever the highest it will allow me, when im done setting the gains, do i change back to the 100 mark... can i leave it at 100, or is it just harder to set the gains on that frequency.

Right, set it as high as it will go, but just for the gain setting process. After you're done, set it back to 100 or whatever (80 is generally recommended).

3.) if i want to disconnect the speakers, what would i do. Just unplug the RCA cables right, since i wouldnt have to unscrew anything.

If you're running a separate amp on the front speakers, disconnecting the RCA's would work fine.

4.) when im doing the gain on my speakers, should i turn off the subwoofers via the option on the deck. would that be ok? wouldn't that make it easier to set the gains.

That should work fine as well.

5.)Should i have bass boast off completely on the sub amp. on the 4 channel amp powering the speakers, whats a good high pass frequency to set it on and test it on.

I'd recommend turning it off completely. For your front speakers, use a 1000 Hz frequency.

Actually, try setting the gains using this method on your front speakers first with 1000 Hz before doing your sub gains. At 1000 Hz, it's VERY easy to tell when the tone is clipping. 1000 Hz gets loud, so use earplugs. But you'll hear the clipping loud and clear.

 

[JohnBlayz142 10+ year member]

DawgDan, you get my approval....you're a helpful guy //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[paintballer 10+ year member]

wow. thanks man. that was great help. one thing left stands that is very very confusing and i dont understand why its doing it. I already posted a question about this too. For some reason whenever i go past 22 on the master volume control on my Alpine CDA-9856, the sounds seem to change both in the speakers and the subwoofers. At first i thought it was just the subs, but now it seems like the speakers too. The subs seem to tone down in a voulme a little and dont stand out as much after going from 22 to 23 and up.. The speakers drop on tone, then they shoot back up. Origianlly i thought the gains that were set by the installers were too high considering i could only get it to 22 before problems start happening. But just to test it out, i turned the sub amp gain down a lot almost at the bottom, and then went back to that transition phase from 22-23 and up, and the same thing happens even though the subs are not even loud considering i turned down the gain. Even after turning down the gain on the subs to almost as low as possible, there still is a sudden change in the sound tone from 23 and up on the master volume. Why would changing the gains drastically not even affect this transition phase from 22-23 and up. Is the deck doing something to the voltages or something. If i turned the gains down alot, wouldnt that mean i could essentially turn the volume up a little higher than before when the gains were higher?I have testes this with the speakers and 4 channel amp yet, but i can mainly hear the change in the bass. But if i go the 22 spot, and then increase the sub volume and bass volume and the BBE, the problem does not occur. This seems strange to me, and its irritating me. is this clipping or just some weird action by the cd player and nothing to worry about.

Thanks again guys for all your help. This is the last questions that i need major help with.

 

[dawgdan 10+ year member]

Sounds like maybe the BBE processing is messing with your speakers. Try turning BBE off and setting all your bass and treble settings flat. The easy way to do this on your head unit is turning Defeat on. Then try pushing it past 22.

 

[paintballer 10+ year member]

Cool.. i work night crew, so i have to go to bed i a few minutes. Ill mess with it tonight at my worksite, and get back to you tomorrow. anyways, thats what defeat is for. I was wondering what the heck that meant.. If its still doing it after i change it, could it be clipping or something is messed up maybe. But if it does stop, then should i procede with the gain settings through the process that you described? THanks ,you have been a great help.//content.invisioncic.com/y282845/emoticons/veryhappy.gif.fec4fed33b4a1279cf10bdd45a039dae.gif

 

[dawgdan 10+ year member]

Yeah, if the problem stops, go for the gain setting. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif Good luck and let me know how it turns out.

 

[xluben 10+ year member]

wow. thanks man. that was great help. one thing left stands that is very very confusing and i dont understand why its doing it. I already posted a question about this too. For some reason whenever i go past 22 on the master volume control on my Alpine CDA-9856, the sounds seem to change both in the speakers and the subwoofers. At first i thought it was just the subs, but now it seems like the speakers too. The subs seem to tone down in a voulme a little and dont stand out as much after going from 22 to 23 and up.. The speakers drop on tone, then they shoot back up. Origianlly i thought the gains that were set by the installers were too high considering i could only get it to 22 before problems start happening. But just to test it out, i turned the sub amp gain down a lot almost at the bottom, and then went back to that transition phase from 22-23 and up, and the same thing happens even though the subs are not even loud considering i turned down the gain. Even after turning down the gain on the subs to almost as low as possible, there still is a sudden change in the sound tone from 23 and up on the master volume. Why would changing the gains drastically not even affect this transition phase from 22-23 and up. Is the deck doing something to the voltages or something. If i turned the gains down alot, wouldnt that mean i could essentially turn the volume up a little higher than before when the gains were higher?I have testes this with the speakers and 4 channel amp yet, but i can mainly hear the change in the bass. But if i go the 22 spot, and then increase the sub volume and bass volume and the BBE, the problem does not occur. This seems strange to me, and its irritating me. is this clipping or just some weird action by the cd player and nothing to worry about.
Thanks again guys for all your help. This is the last questions that i need major help with.

this is DEFINITELY the BBE feature. you can audibly hear the change at that point on all alpine head units.

turn it off and never use it. also always leave bass and treble at 0. sub out at +15 as previously mentioned. i set the gains to max at 25/35 on the main volume.

i would highly suggest going to radioshack and getting a $30 DMM to set your gains properly. it will give you much better idea of whether or not you are clipping.

i honestly think it's quite hard to hear clipping through a sub. even if you use a 250Hz tone (which i've never heard of doing, and don't think it's a good idea).

also, if 250Hz is the highest point on the low pass filter, you will be hearing the -3dB point. which means if you do set it properly (not clipping) at 250Hz anything lower will be plaing 3dB higher, and that takes double the power, which means, probably clipping //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

if you buy a DMM and go to the Amplifier section of the forum and read the amplifier setting sticky you should have a better idea of what you are doing. use a 0dB tone and you will know (fairly certainly) that you won't be clipping.

 

[dawgdan 10+ year member]

i would highly suggest going to radioshack and getting a $30 DMM to set your gains properly. it will give you much better idea of whether or not you are clipping.

False. A DMM cannot indicate clipping. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif The only thing you can use a DMM for, in regards to setting gains, is to estimate the power you're sending to a certain load. When doing this, you're likely not using an amplifier to its full potential - only a number in your head of what "should" be the maximum the amp can put out since manufacturers underrate (and overrate) their amps all the time.

http://www.resnet.trinity.edu/areynol1/gain.htm

Not to start an argument, but I trust my ears above all. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif It's a fairly accurate method, and whether it's a 250 Hz tone or a 50 Hz tone, as long as they are recorded at the same level (in this case, 0db), the amplifier still clips at the same setting. It's just that a 250 Hz tone makes it a little easier to hear the change in pitch when clipping occurs.

 

[xluben 10+ year member]

False. A DMM cannot indicate clipping. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif The only thing you can use a DMM for, in regards to setting gains, is to estimate the power you're sending to a certain load. When doing this, you're likely not using an amplifier to its full potential - only a number in your head of what "should" be the maximum the amp can put out since manufacturers underrate (and overrate) their amps all the time.

i tried to state my words carefully to not mislead anyone, but i guess i didn't. //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

a DMM can NOT indicate clipping!

but can be a useful tool when setting gains. if you use a 0dB tone, most likely it will set your gains too low.

but if the amp is VERY overrated, it still could clip. that's why i threw in the "fairly certain" before "not clipping". //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

http://www.resnet.trinity.edu/areynol1/gain.htm
Not to start an argument, but I trust my ears above all. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif It's a fairly accurate method, and whether it's a 250 Hz tone or a 50 Hz tone, as long as they are recorded at the same level (in this case, 0db), the amplifier still clips at the same setting. It's just that a 250 Hz tone makes it a little easier to hear the change in pitch when clipping occurs.

didn't get a chance to fully read that page, but it seems to be a good place to start if you want to set your gains.

BUT

i still do not agree with using the same frequency tone as low pass filter setting.

this IS, by definition, going to set the pass band to 3dB above the level you set the gains at.

this requires a doubling of power, and most likely will cause clipping.

also, i don't trust my ears at all to detect clipping, but this (obviously) varies from person to person. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

i just think that an inexperienced user probably isn't the best at detecting light clipping (which can cause excessive heating of the coil, but not necessarily blow a sub right away).

PS. thanks for not starting a flame war. just trying to spread (hopefully correct) info. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[paintballer 10+ year member]

thanks guys for all the help/ i have to leave for work now. Ill check things out. i downloaded a whole list of test tones, so ill try both. il see what happens.

 

[paintballer 10+ year member]

Ok i did a few things. The 22-23 and up voulme problem was caused by the BBE. i left bass and treble on +2, and the change in volume was good. I tried doing the gains, but its so loud and hard. I had the volume only on like 15, and i was doing the 100 Hz test tone, and the gain was only like 1/5, and it was insanely loud already. It was hard to tell because the other 4 channel amp was rattling. i did unplug all RCA from the 4 channel amp, so just the subs were running. I did notice a change in sound as i kept raising the gain, but the change happened at such a low gain setting. could this be normal.

and something else has failed now. Im really startiong to get pissed at the installers. they did a shitty job. They even had the RCA cables swtiched all over. example, if you would have the fader on rear and balance on left, the front right speaker would be playing only. and by doing this messing around, i noticed that my front right speakers doesnt even work. its a component speaker, and the tweeter still works, just not the speaker. The front left both speaker and tweeter are working fine. SO what the hell could have happened now. Im getting so pissed off at the installers. plus they broke my little cup holder in the rear of the car too. IT was audio express in northern california. they didnt set my gains right either it seems to my knowledge. Pretty much i think they were a bunch of f+++ idiots who had no clue what they were doing even though i payed so much f*** money for this crap. Im so frustrated.

you guys have a been a big help. THanks.

EDITED 10:57 pm. i went back to the place where i got the sound system installed. They fixed the speaker, it had just got disconnected from the crossover board under the door panel. As far as my gains, i still need to do those. I just dont know what a clipped subwoofer sounds like.should i unplug all speaker RCA's or justt he fronts. is a 100 hz test tone fine?

Thanks