Sub and Amp advice needed

[AshleyL]

To get straight to the point, I have purchased a JBL-GTO1214 subwoofer with an RMS of 350W

http://caraudiosecurity.com/shop/product/products_id/9742.html

I have also bought a JBL GT5-A402 amplifier with an RMS of 120W when bridged

http://caraudiosecurity.com/shop/product/products_id/11555.html

Is it safe to run the sub from this amp?

I have been reading that if the amp is to low on power compared to the sub this will likely damage the subwoofer. One site said the amp should have a power of at least 75% of the sub power.

Thankyou for any help

Ash.

 

[Dragon Man]

i am not an expert when it comes to audio but from what i know about radio transmitters and aerial matching/tuning, is you can have too much power going into a an aerial (in this case a sub) and it is not rated for it you can blow it.

if the amp is not powerful enough to run the sub i think it will just come to a point where it will not get any louder. you will however be running the amp at 100% constantly.

hmm, i guess the only way would be to manually set the amp's gain to a lower level if the sub was smaller.

 

[AshleyL]

i am not an expert when it comes to audio but from what i know about radio transmitters and aerial matching/tuning, is you can have too much power going into a an aerial (in this case a sub) and it is not rated for it you can blow it.

if the amp is not powerful enough to run the sub i think it will just come to a point where it will not get any louder. you will however be running the amp at 100% constantly.

hmm, i guess the only way would be to manually set the amp's gain to a lower level if the sub was smaller.

I'm guessing that running a sub at 100% all of the time is not a good thing? I also read something about clipping and this is what kills the sub. Do you know anything about that?

I am now thinking that i will just sell the amp and buy a higher rated one to be on the safe side. I was thinking about getting a 4 channel amp and using it to power the sub and my components up front. Is that ok to do so or would i have to get a separate amp for my sub and components?

What exactly does the gain on an amp control?

Thanks,
Ash

 

[mirafioriman]

Using a four channel amp to power the sub and your front components is a sensible idea in terms of cost effectiveness and use of space. It keeps the wiring easier too and is a quite common practice.

The gain is an adjustment on the amp used in setting up. You want it as high as possible but before distortion to get the maximum out of your amp and speaker in terms of power output and therefore volume.

Underpowering a sub is generally a bad idea and can be worse than overpowering. Most amps rarely produce their maximum power output in everyday use so if you use a 500 watt amp on your 350 watt sub then it's unlikely the sub will see the full 500 watts often if ever. If you underpower the sub the amp then struggles and can go into distortion (often known as 'clipping') this is when part of the signal is 'chopped off' by the amp. This can cause damage to speakers. Clipping can also be caused if the gain is set incorrectly (too high) Basically the lower you can set the gain the better as you'll allow the amp to have an easier life and get better sound quality with a lower level of distortion.

There is always some distortion present, although at lower levels you can't always hear it. It's an important thing to check for when looking at amp specs when buying as well as the power output and signal to noise ratio.

 

[AshleyL]

Using a four channel amp to power the sub and your front components is a sensible idea in terms of cost effectiveness and use of space. It keeps the wiring easier too and is a quite common practice.

The gain is an adjustment on the amp used in setting up. You want it as high as possible but before distortion to get the maximum out of your amp and speaker in terms of power output and therefore volume.

Underpowering a sub is generally a bad idea and can be worse than overpowering. Most amps rarely produce their maximum power output in everyday use so if you use a 500 watt amp on your 350 watt sub then it's unlikely the sub will see the full 500 watts often if ever. If you underpower the sub the amp then struggles and can go into distortion (often known as 'clipping') this is when part of the signal is 'chopped off' by the amp. This can cause damage to speakers. Clipping can also be caused if the gain is set incorrectly (too high) Basically the lower you can set the gain the better as you'll allow the amp to have an easier life and get better sound quality with a lower level of distortion.

There is always some distortion present, although at lower levels you can't always hear it. It's an important thing to check for when looking at amp specs when buying as well as the power output and signal to noise ratio.

Thanks for the advice. Im still not too sure on it all. Would you be able to say whether this amp http://caraudiosecurity.com/shop/product/products_id/8036.html would be ok to power this sub http://caraudiosecurity.com/shop/product/products_id/9745.html

The amp is 200w rms bridged. Sub is 350w rms.

Thanks,

Ash

 

[mirafioriman]

The JBL sounds like a decent amp for the money, although if you can stretch your budget a little I would try to get an amp that produces 300 or more watts RMS to power the sub.

Alternatively you could use a sub that has a lesser rating that needs 200 watts or so RMS instead.

 

[AshleyL]

The JBL sounds like a decent amp for the money, although if you can stretch your budget a little I would try to get an amp that produces 300 or more watts RMS to power the sub.

Alternatively you could use a sub that has a lesser rating that needs 200 watts or so RMS instead.

Would you still recommend that bearing in mind i wont be having the sub up to max or anywhere near?

And also the thing is i should have thought about all this before i bought it lol. I already have the sub and the even less powerful amp that i linked in my first comment.

Im thinking of buying a new amp and selling the other one cheap for as much as i can get or using it to power my front components.

 

[mirafioriman]

Using an amp to power the front components should improve the quality of your system so that would be a good use of the amp you already have.

If you run the sub from a lesser power amp like you have conservatively with the gain set correctly it's unlikely to damage the sub, although you may not get the best from it performance wise.

To be honest in the best sound quality installs the sub(s) don't do that much anyway

 

[AshleyL]

Using an amp to power the front components should improve the quality of your system so that would be a good use of the amp you already have.

If you run the sub from a lesser power amp like you have conservatively with the gain set correctly it's unlikely to damage the sub, although you may not get the best from it performance wise.

To be honest in the best sound quality installs the sub(s) don't do that much anyway

Yeah i will most probably do that then my components are only 50w rms though. Obviously if the amp is giving then 40w rms each, will it be much better than just powering them from the head unit? I know it will be but by how much?

I just purchased this amp http://caraudiosecurity.com/shop/product/products_id/16243.html its 350w rms so that will be 'perfect' i suppose? I dont want to run the risk of damaging the amp and sub and have to replace both.

Thanks,

Ash.

 

[volxstu]

You will be unlikely to blow the amp through clipping, just the sub. Amps normally go through earth faults so just make sure you have a good solid earth on bare metal.
If you are concerned about clipping the sub (normally found by adding too much boost/ volume at the head unit or not matching the gain to the input voltage of the RCA's) then try a local audio shop to see if they can scope it for you. I would charge around £20-£30 but if it gives you piece of mind then it's worth every penny. Also if a professional touches a system to scope they will check your wiring. Nobody wants to get involved in a system un safely wired so they will advise you and possibly even fix any potential issues.

 

[AshleyL]

You will be unlikely to blow the amp through clipping, just the sub. Amps normally go through earth faults so just make sure you have a good solid earth on bare metal.
If you are concerned about clipping the sub (normally found by adding too much boost/ volume at the head unit or not matching the gain to the input voltage of the RCA's) then try a local audio shop to see if they can scope it for you. I would charge around £20-£30 but if it gives you piece of mind then it's worth every penny. Also if a professional touches a system to scope they will check your wiring. Nobody wants to get involved in a system un safely wired so they will advise you and possibly even fix any potential issues.

Oh right i see, i have a friend of a friend who can install car audio so ill ask him for advice.

The mono amp i bought JBL GTO-501ez apparently has a gain setting CD and there are lights on the amp red and green to tell you if it is set correctly so hopefully i will be able to do this myself.

How fiddley is it to amp the door speakers? As im guessing the wire would have to be threaded through the pipe that takes the wires from the car to inside the door. Loks a bit tricky to me.

Thanks,

Ash

 

[volxstu]

For now I would just wire the speakers to an amp the easy way. Just cut through the ISO adaptor speaker wires at the head unit and connect up there so it utilises the standard wiring going through the door. Then you can cut off the plug that would normally connect to the mid bass and extend to the crossover from there.

 

[AshleyL]

For now I would just wire the speakers to an amp the easy way. Just cut through the ISO adaptor speaker wires at the head unit and connect up there so it utilises the standard wiring going through the door. Then you can cut off the plug that would normally connect to the mid bass and extend to the crossover from there.

I kind of think i know what you mean.

With the ISO adapter speaker wires do i just take them out from where they would go into the head unit and attach them to the amp speaker wires instead?

But what do you mean when you say to:

"cut off the plug that would normally connect to the mid bass and extend to the crossover from there" ?

Thanks,

Ash