Help with subwoofer voltage

[nstillmatic 10+ year member]

Hi, my setup is in my sig. I'm trying to power two SR124's (wired to 1ohm) with a Sundown 1200D. Polk lists each SR124 as 700WRMS and 1400W peak.

Anyway, I used the calculator on the12volt to come up this: sqrt(1400RMS x 1ohm) = 37.4V.

I have the volume on the headunit up ~95%, and the clarion eq volume and sub control up all the way as I used the DMM to set the gain at 37.4. Now when I play music at a listenable level you can barely hear the subs at all, whereas the mids/highs are great. I have to turn the sub level and volume up all the way to really get a decent amount of bass. Did I do the calculation wrong? Should I be setting the gains a lot higher?

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[helotaxi 5,000+ posts]

Your first failing is that your calculation is worthless because regardless of what your subs are rated for the amp is only going to give you 1200W. Set the gain by ear listening for the slightest hint of distortion.

 

[nstillmatic 10+ year member]

I said in the post that the sundown amp is underrated and really puts out 1400-1500W.

 

[ciaonzo 5,000+ posts]

I said in the post that the sundown amp is underrated and really puts out 1400-1500W.

So what's the problem? He gave you the best advise you're going to get. Do it by ear and listen for the onset of distortion and watch the mechanical limits. I'm sure by that point you'll have already overwhelmed your front stage and you can back it off to match up.

 

[bubbagumper6 5,000+ posts]

I don't really agree with the "setting gains by ear" method for subwoofers since distortion is fairly difficult to hear in those lower frequencies, especially for someone new to the game.

 

[ciaonzo 5,000+ posts]

I don't really agree that "distortion is fairly difficult to hear in those lower frequencies" unless you have very little experience, in which case, you should either deal with the results of your unnecessarily-low gain settings and subsequent lack of real-world bass, or take it to someone who knows more than you do.

 

[bubbagumper6 5,000+ posts]

I don't really agree that "distortion is fairly difficult to hear in those lower frequencies" unless you have very little experience, in which case, you should either deal with the results of your unnecessarily-low gain settings and subsequent lack of real-world bass, or take it to someone who knows more than you do.

And where do you propose someone acquire this experience?

 

[nstillmatic 10+ year member]

Yeah I'm not sure what distortion sounds like on subwoofers. I'm just being very cautious. I thought going over that calculated voltage was a bad thing that should cause distortion, that's why I made this topic. So it's okay to go far above that if you don't notice distortion then I'm guessing?

BTW, I reached that voltage without setting the gain knob much further than halfway.

 

[ciaonzo 5,000+ posts]

And where do you propose someone acquire this experience?

Therein lies the answer - practice. This really isn't as hard or as dangerous as you guys like to make it out to be. I'd like to think that everyone knows what mechanical stress sounds like and surely everyone knows at least one song well enough to identify when it doesn't sound as it should when the amplifier is adding it's own "signature". The amp and sub are most often found in the trunk, very near each other, right? Play some familiar music through the sub only (no fronts) while adjusting the gain and when it begins to sound stressed or it's loud enough for you, stop. If you're not hearing gross amounts of electrically generated amplifier distortion or mechanically generated driver distortion, the you're probably not going to do much damage to the driver because most music is dynamic in nature. You could even take baby steps and make small adjustments over a few days to be on the safe side.

 

[helotaxi 5,000+ posts]

I said in the post that the sundown amp is underrated and really puts out 1400-1500W.

How do you know this? Did you put it on a bench with a massive power supply and test it, or are you going by what others have said?

 

[sackamous 10+ year member]

Hi, my setup is in my sig. I'm trying to power two SR124's (wired to 1ohm) with a Sundown 1200D. Polk lists each SR124 as 700WRMS and 1400W peak.
Anyway, I used the calculator on the12volt to come up this: sqrt(1400RMS x 1ohm) = 37.4V.

I have the volume on the headunit up ~95%, and the clarion eq volume and sub control up all the way as I used the DMM to set the gain at 37.4. Now when I play music at a listenable level you can barely hear the subs at all, whereas the mids/highs are great. I have to turn the sub level and volume up all the way to really get a decent amount of bass. Did I do the calculation wrong? Should I be setting the gains a lot higher?

Ok first let me say I am no expert what so ever! I think u answered your own question though. You said you set the gain with the volume at 95%. Then noted that you have to turn it all the way up for your subs to perform. Well of corse that is were you set the gains at. Try setting them with the volume a few clicks above were you normally listen. Then your amp will put out at lower volumes just rember you will prob get some clipping or distortion or what ever it's called when you do turn it all the way up. At least I think it should work that way.

 

[Haunz 10+ year member]

Hi, my setup is in my sig. I'm trying to power two SR124's (wired to 1ohm) with a Sundown 1200D. Polk lists each SR124 as 700WRMS and 1400W peak.
Anyway, I used the calculator on the12volt to come up this: sqrt(1400RMS x 1ohm) = 37.4V.

I have the volume on the headunit up ~95%, and the clarion eq volume and sub control up all the way as I used the DMM to set the gain at 37.4. Now when I play music at a listenable level you can barely hear the subs at all, whereas the mids/highs are great. I have to turn the sub level and volume up all the way to really get a decent amount of bass. Did I do the calculation wrong? Should I be setting the gains a lot higher?

Let me guess... you set the gain with no load hooked up to the amp...

If that is the case then it underlines the stupidity behind the 'gain setting methods' touted by so many people who don't have a clue what they are talking about... YOU NEED A LOAD HOOKED UP TO THE AMP... preferably a non-inductive dummy load... you also did not mention what kind of meter or test signal you used... both are very important if you want proper results... MUSIC WILL NOT WORK RIGHT...

On that note I agree with ciaonzo... gain should be set by ear... not necassarilly to protect your drivers from thermal damage, but to match sound levels.... Of course if you are a bass head and are worried about blowing up your gear setting with a dmm can help...