Setting the gain on my amp/sub

[DJKOR]

Excuse me if this is a bit long, but I can't help it when I need to write stuff up. Anyways, when it comes to audio, I'm not all that knowledgeable. I know all the wiring and the basics of getting it running, but when it comes to driving it to do what it has the potential to do, I usually get scared of blowing something up.

So in my car I have an MTX 300W Monoblock driving a MTX Sledgehammer 7500 which is rated at 400W. Firstly I know that I probably should have gone for an amp rated at 400W, but I didn't want to push my luck (MTX also says an amp between 200W-400W will be suitable). Anyways, I have been using it for a few months already and I keep getting the feeling that this subwoofer has much more potential than what I get out of it. Now I'm not looking to run it at full bore all the time; just every so often when there is good song. Anyways, its hard to say how hard I push it, but the best way to describe it is that at most, I run it at a level which makes the parcel shelf and spoiler buzz lightly. occasionally my sunglasses in the overhead holder as well.

The sub itself doesn't really show much excursion when I it is running at a level that I think is high. Just to give an idea, this is the amp and sub that I am using:

Subwoofer - MTX T7512-44 (Tech Specs) in Sledgehammer enclosure:

Amplifier - MTX Thunder 300XD:

Now this part is hard to explain, but anyone with an MTX amp with the remote gain feature should understand. On the amp itself, I have the gain set to about '3V' on the scale of 5V-0.25V. This equates to about 1/5 of the maximum gain. My amp is fed from the RCA pre-outs on my head unit which unfortunately I can not determine what level that is. The bass boost on the amp is all the way down. Then my bass is controlled from the remote gain module which I usually have set to 4/5 of maximum. From the looks of things, this remote gain module just seems to be a control to adjust the gain from 0 all the way to the maximum you have set on the amp.

An EBC (External Bass Control) is a Remote Subwoofer Level Control (Remote Gain) - Let's say the amplifier's gain is set at halfway, when the remote subwoofer level control is plugged in, you now have external control of the gain from zero to halfway. The installation of this level control is NOT necessary to get full power from the amplifier. Note: One EBC (External Bass Control) can control two or more amplifiers using a mini plug Y adapter.

So onto why I started this thread. I feel that I can increase my gain higher than it is at the moment. The problem is, I just worry that I am going to blow my sub up. I don't plan to increase it to competition levels, I just want it to be running higher as I think that I'm not pushing it and getting my money's worth out of it. I was looking on Youtube and saw videos like the following and my question is; can a subwoofer like this really run at a level like that safely? Not that I want to run it that hard, but just to know that if I am pushing at least 3/4 of that level, that I should be relatively safe from blowing it up. I know it's a bit of a difficult thing to answer as every setup is different, but from looking at the video, that just seems insane.

Please wait a few seconds for Video to Load!

Probably not the best video but it's the only one i can find at the moment that shows the excursion the best. I'm guessing that I can safely go up to '2V' on the gain and work from there, but even though it may sound stable, I'm worried whether or not it is quietly dying without me knowing. Or another scenario would be that there is a sudden bass beat in a track which is something stronger than usual and that ends up killing something. I know I sound a little paranoid, but I just don't want any bad surprises.

[the_random_hero]

When do you want me around to tune your gear for you? :P

[DJKOR]

Did some more playing around today. I really think I need to change my music style in the car if bass is my target. I thought a lot of my electro/techno had a lot of bass in it, but I guess I was wrong. Put some RnB on and... wow. Even still though, pushing it hard, the excursion on my sub is around about half of that in the video attached in my first post.

I have a feeling my pre-outs are 2V so I reckon I have the potential to push the gain a little higher (it's amazing the difference a small turn does on that thing) so that at least I am getting more out of the main style of music I listen to.

When do you want me around to tune your gear for you? :P

Hehehe. Thanks man. I'll see how I go. If I can get my hands on an oscilloscope, I'll use that to keep an eye on any clipping while I set it up. Having the amp rated 100W, that should really be the only thing I need to worry about right? It's just with things so loud, I don't know how I would spot any clipping.

[the_random_hero]

Re-add me on MSN (I don't know if you still have me on there, if not it's the_random_hero_drew@hotmail.com) and I'll give you a rundown on how to set your gains properly.

Clipping is generally pretty easy to hear, once you know what to listen for.

[akuma]

dont you have a subwoofer level controller if your running an after market headunit? maybe put it on low, set the amp gains up a bit higher, then when your want to feel that bass, you can set the subwoofer level higher :) with the remote bass controller, ive got one as well, but i rarely use it, you can hear and feel the difference but not as much as you expect it to be.

[the_random_hero]

dont you have a subwoofer level controller if your running an after market headunit? maybe put it on low, set the amp gains up a bit higher, then when your want to feel that bass, you can set the subwoofer level higher :) with the remote bass controller, ive got one as well, but i rarely use it, you can hear and feel the difference but not as much as you expect it to be.

Most sub level controllers I've used go from 0-10, so the same a volume control. I remember doing a Rodeo with a single 12" sub in a big ported box - the controller let the owner go from a light doof to half an inch of rear window flex :P

It's much easier to turn a knob than it is to get into menu settings on your headunit (provided you mount it somewhere smart) :)

[akuma]

i got mine right near my coin slot, easy to access :)

[JJCRU23R]

yea this is a good question. ive previously just played around with the settings until i found what i though was suitable for my music, etc.

is there a set of rules you need to go by to ensure you get the most out of your subs without blowing it up?

[DJKOR]

Well most people get away with the simple method of adjusting it by ear. In this way you turn your gain on the amp all the way down, put your head unit up to about 3/4 full volume, then slowly increase gain until you hear some clipping, then turn the gain knob back slightly. This is how I've done it in the past, but I want to do it accurately this time around since I spent quite a bit on my sub.

I've so far set mine up electronically using a multimeter which should get me fairly close until I can get my hands on an oscilloscope to make sure that it is correct. In the meantime, this is how it is running. The sub has nowhere near as much excursion as the one in the original video I posted at the beginning but bear in mind that my amp is rated at 300W whereas the sub can take up to 400W. The video doesn't quite capture it properly either; it does more a little further than shown. Either way, it would be good to see though how much more I can push it while still keeping it in its boundaries. I'm not a fan of the 'by ear' method since I'm not so good at hearing clipping at lower frequencies.

As for the remote gain control, I've always had it mounted within an arms reach beside the A/C controls. I now leave this on 100%, and if the bass is ever too much, I can always turn it down.