I can't tell if I'm hurting my subs - diyAudio
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Old 15th August 2008, 01:23 AM   #1
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Default I can't tell if I'm hurting my subs

Well, I've looked through some of the threads on this site and I take it bottoming out hurts the voice coil and can ruin a sub, right?

Anyways, I have 4 MA Audio subwoofers (MA120XE, 12", 350 watts RMS) installed in a single box about 6.5-7 cu feet (before displacement). The subs hit hard, and I'm only pushing 1000 watts RMS to them just to be on the safe side. Turning up the gain some though obviously makes them hit harder, but I don't know if I'm bottoming them out or not. How can I tell?
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Old 15th August 2008, 01:24 AM   #2
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They make a nasty clacking sound.
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Old 15th August 2008, 01:59 AM   #3
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Too much gain is counterproductive, and turning up the gain beyond what is correct doesn't make an amp produce more power, or make subs "hit" harder. But it will certainly cause distortion, which may cause your subs to sound like you are overdriving them.

Are you sure of your settings?
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Old 15th August 2008, 09:44 AM   #4
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Quote:
Originally posted by 69CamaroSS396
Too much gain is counterproductive, and turning up the gain beyond what is correct doesn't make an amp produce more power, or make subs "hit" harder. But it will certainly cause distortion, which may cause your subs to sound like you are overdriving them.

Are you sure of your settings?

It's hard to know if they're clacking, my van rattles too much to differentiate the two things.

Well, I have the gain at about +5dB, not anything like +12. They don't sound distorted, at least not through my vans rattling, but would the clacking sound of it bottoming out be like a triangle (the musical instrument), or like a 50 lb piece of steel falling onto more steel.
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Old 15th August 2008, 10:53 AM   #5
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you could be hearing the sound of a square wave, if the amp is being over driven by having the gain too high on the head unit or the amp. some amps can be over driven even with the gain set to a mid to low level, it depends on the head unit RCA preamp output voltage, if thats what your using, make sure that the voltage input rating for the amp is set to handle what ever voltage the head unit can send.

bottoming out a speaker is most of the time a loud clonk, you should not look to hear for the clonk as a guide to too much power, since it can easily kill the sub,. check the output voltage on the amp, and calculate power output and set it below the recomended by the manufacturer, you can also check the shape of the output wave using an oscilloscope to make sure its not square, you can measure the voltage with the scope so you can again calculate power output of the amp, once this is done make sure that there is no bottoming out of the sub.

what amp are you running on those subs?
and what head unit?


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Old 15th August 2008, 02:27 PM   #6
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bottoming out sounds really mechanical.

Think about what is hitting what...the former is smashing into the steel backplate.
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Old 15th August 2008, 03:07 PM   #7
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bottoming out sounds really mechanical.
Very. Tap a PVC coupler or a heavy plastic drinking glass on a counter top, sounds something like that. Not likely to be confused with rattles.

Trouble is, they can bottom out lightly without being very audible. Though not as serious as really slamming the backplate, it can still distort the VC former and have cumulative effects.
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Old 15th August 2008, 04:12 PM   #8
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Quote:
Originally posted by ninjatanzen



It's hard to know if they're clacking, my van rattles too much to differentiate the two things.

Well, I have the gain at about +5dB, not anything like +12. They don't sound distorted, at least not through my vans rattling, but would the clacking sound of it bottoming out be like a triangle (the musical instrument), or like a 50 lb piece of steel falling onto more steel.
I think the gain needs to be set correctly before going any further. It can't be total guesswork. Sounds like you may not be sure whether it's correct or not. Maybe you are, but if that is taken out of the equation, the troubleshooting becomes less complicated.

As mentioned, you need to know whether the head unit and amp/amps are even compatible.

This reminds me of a situation I encountered in my neighborhood. A local kid had an Eclipse HU w/8V pre-outs, an audiobahn 4 channel amp driving his front stage, and an older yard sale Alphasonik 2 channel bridged driving his subs. The audiobahn could handle the 8V, but the older amp only accepted up to 1V input. Bad deal because the old amp was driven to its rated power with well less than 1/2 volume from the HU. From that point to the user's actual listening level, the old amp was being driven from mild into severe clipping.
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Old 15th August 2008, 11:16 PM   #9
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Quote:
Originally posted by boricuaso
you could be hearing the sound of a square wave, if the amp is being over driven by having the gain too high on the head unit or the amp. some amps can be over driven even with the gain set to a mid to low level, it depends on the head unit RCA preamp output voltage, if thats what your using, make sure that the voltage input rating for the amp is set to handle what ever voltage the head unit can send.

bottoming out a speaker is most of the time a loud clonk, you should not look to hear for the clonk as a guide to too much power, since it can easily kill the sub,. check the output voltage on the amp, and calculate power output and set it below the recomended by the manufacturer, you can also check the shape of the output wave using an oscilloscope to make sure its not square, you can measure the voltage with the scope so you can again calculate power output of the amp, once this is done make sure that there is no bottoming out of the sub.

what amp are you running on those subs?
and what head unit?


laters

Ok, you and someone else asked the same question. The head unit is a Pioneer DEH-1500 with and output of 2.2V
The amp is a Alpine MRP-M1000 and has a separate knob for the gain and the Voltage; the Voltage can be set from 0.2-4V, but it's almost guess work as there are no indications as to what you're set at.

I think my dead uncle has an oscilloscope sooo I'll have my brother pick that up and check it out for me.

Sorry it's taking me forever to reply, I'm under the lil noobie moderation thing.
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Old 16th August 2008, 01:15 AM   #10
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Quote:
Originally posted by ninjatanzen



Ok, you and someone else asked the same question. The head unit is a Pioneer DEH-1500 with and output of 2.2V
The amp is a Alpine MRP-M1000 and has a separate knob for the gain and the Voltage; the Voltage can be set from 0.2-4V, but it's almost guess work as there are no indications as to what you're set at.

I think my dead uncle has an oscilloscope sooo I'll have my brother pick that up and check it out for me.

Sorry it's taking me forever to reply, I'm under the lil noobie moderation thing.
Explain what it says on the two controls you mentioned above. I have never used Alpine amps, but it sounds as though you are describing the bass EQ, (0dB-12dB@50hz), and the gain or input sensitivity adjustment, which is marked in V, and these are two completely different things.
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