[ontopofm]

thanks a bunch

[Atsnow]

Originally Posted by VP Electricity

If that's all the current you want your amp to pull, shouldn't you downgrade the amp's internal fuses as well? I just don't get it.

The simple thing to remember is that if two fuses of different values are in series, the lowest-value fuse always blows first.

The fuse on the amp protects the amp. The fuse at the battery protects the wire (and the amp, IF the amp has no internal fuse).

If you had 2 amps fused at 60A each, and one wire with a distribution block supplying power to these two amplifiers, and a 120A fuse at the battery for that one power wire, how would that battery fuse be protecting either amp? It wouldn't. The amp's protection comes from the internal fuse, and if it doesn't have one, then you would need a fused distribution block with individual fuses for each amplifier.

If you have an amp that pulls more current with a 2 ohm load than at a 4 ohm load, the internal fuse from the factory will be appropriate for the worst-case ohm rating (a higher rating). But if the amp is wired to the easier 4 ohm load, then the number of amperes the amp pulls should remain lower than its "worst-case" internal fusing rating, and in that case you can usually get away with a fuse smaller than the amp's internal fuse. But if you don't know how to do the math involved, it's definitely safest to use the same, NOT a lower value - and the risk of using a larger value at the battery is essentially zero.

Or have your fuse blow every time the bass hits.

Originally Posted by Technic

I rather have a fuse blown for no good reason than an amp blown for a bad reason...

Call me extra cautious but like Technic I recommend to go slightly lower then the amp rating at the battery, (i.e. on my current mono amplifier which uses 4 X 20 amps fuses I use a 40amp fuse at the battery and a 60amp before the amplifier) I believe that if you’re properly wired with quality cables and well grounded there is no reason for that fuse to blow even playing very loud at high current settings.

I only use high quality equipment ( old Xtant, USAmps, Orion. PPI) and want them to be well protected


BTW I also recommend that you fuse as close to the battery as possible

[ontopofm]

you use 2 fuses 1 after the battery and 1 before the amp to protect both battery and amp? but if you total up both fuses it it would be greater than the amp rating at the amplifier. isnt it the same as using a larger fuse at the battery?

[VP Electricity]

If two fuses are in series - the output side of one fuse feeds the input of the other - the smaller fuse is the effective current limit. Before the larger fuse's capacity can be reached, the smaller fuse will blow.

If two fuses are in parallel - where their battery input side are tied toegether and their output side are tied toegether - then they add together.

As Technic has pointed out recently, it's our own car, we can do what we want with it (regardless of what physics says).

I too use good quality gear, I too know that if it is wired properly fuse blowing should never be an issue. I also put my fuse very near the battery, because it can only protect the wire after the fuse, not before it.

If you run the amp at 4 ohms, but it's 2-ohm stable, the internal fuse probably bigger than you will ever need anyway, so fusing with a smaller rating at the batery will probably not ever be an issue. But if you don't know how to do the math, just use the same size fuse and don't worry about it.

[theanhdy]

I have this old JBL BP 300.1 sitting around. Is it powerful enough to power two sws-8?

Output 4 Ohms 150W x 1
Output 2 Ohms 300W x 1
Signal-to-Noise Ratio >100
Frequency Response (±3dB) 20Hz - 500Hz
Total Harmonic Distortion 0.1%
Input Sensitivity 250mV - 4V

[LaYzEe]

Originally Posted by theanhdy

I have this old JBL BP 300.1 sitting around. Is it powerful enough to power two sws-8?

Output 4 Ohms 150W x 1 Output 2 Ohms 300W x 1
Signal-to-Noise Ratio >100
Frequency Response (±3dB) 20Hz - 500Hz
Total Harmonic Distortion 0.1%
Input Sensitivity 250mV - 4V

Im assuming this is a mono amp right? I think you'll be fine at 4 Ohms 150W since the SWS-8s are 150 RMS/ 300 Peak. Just run it parallel at the 4 Ohms and you should be good to go.

[Atsnow]

Originally Posted by LaYzEe

Im assuming this is a mono amp right? I think you'll be fine at 4 Ohms 150W since the SWS-8s are 150 RMS/ 300 Peak. Just run it parallel at the 4 Ohms and you should be good to go.

Layzee be careful not to confuse different impedence rating and peak power and also when you run speakers in parallel you reduce final impedance
Here's a simple write up on the subject
http://www.usspeaker.com/speaker%20wiring-1.htm

Originally Posted by theanhdy

I have this old JBL BP 300.1 sitting around. Is it powerful enough to power two sws-8?

Output 4 Ohms 150W x 1
Output 2 Ohms 300W x 1
Signal-to-Noise Ratio >100
Frequency Response (±3dB) 20Hz - 500Hz
Total Harmonic Distortion 0.1%
Input Sensitivity 250mV - 4V

Just to make things more clear

Your SWS-8s are each 4 Ohms , you will need to wire them in parallel thus wired your final impedance will be 2 Ohms

Your amplifier being rated at 300W at 2 Ohms this should be plenty of power to drive the speakers

Here's an image of parallel wiring

[LaYzEe]

stupid me, you can clearly tell now it was my uncle who did all the wiring for my install rofl . Sorry theanhdy if i got you confused.

[theanhdy]

Thank you very much guys. I have a 135i with basic standard audio (US). I hope I can replace the subs under my seats with these SWS-8. I'm trying to find an online store to buy these subs but I'm having a hard time.

[Asclepius]

This is prob a stupid question but since I know nothin about audio instal I have to ask. Is it possible to just swap out the original amp and speakers without running new wiring?

[Autobot]

subscribed

[Autobot]

Would the MTX 600XD be too much or little for this set up?

[dinkoh]

Replacing the stock subs is a better idea than getting something in your trunk. The bass is louder from the outside than inside the cabin! And, it takes up too much space in the trunk. I wish someone knew had to do it in my area.

[Atsnow]

Originally Posted by Autobot

Would the MTX 600XD be too much or little for this set up?

Should be perfect, as long as you keep the gain in check

[LaYzEe]

Originally Posted by Autobot

Would the MTX 600XD be too much or little for this set up?

DAMN, thats like 2x more than mine It'll def. make ur subs bump!

[jcarlucci1]

I am running an mtx 300w rms amp into the sws-8, and cant put the gain above 1/4.. I think 600 is WAY too much

[Technic]

Originally Posted by Autobot

Would the MTX 600XD be too much or little for this set up?

Although it could work as long as you keep the gains and the volume relatively low, it will be more of a short term solution before you start liking the "thump" too much until it goes "pop". After all, it is double the rms power rating of the subs, not the peak.

So I don't see the benefit of getting an amp that you need to "castrate" first -sorry for the mental image- to do its job. I would get something that does its job without any restrictions for the long term.

[Autobot]

So what kind of amps would you guys reccomend that is enough but not overkill? What should I be looking for in an amp to power them? Mono, A/B or D, how many channels, Min RMS per channel, stuff llike that. I'm not tyerin gto go overboard, just maybe some reccomendations of a decent one that isn't crazy expensive. Thanks

What about this one? Seems to be perfect, 150 RMS @ 4ohms
http://cgi.ebay.com/JL-AUDIO-300-2-C...742.m153.l1262

This one looks ok but under powered for the SWS's
http://www.crutchfield.com/App/Produ...=THA275&tp=115

And lastly this one:
http://www.e90post.com/forums/showthread.php?t=127105

Thanks again for the help guys

[rubber_ducky]

Did I read in here that earthquake are coming out with 2ohm versions of these subs? If so, these will be drop-in replacements for the OE subs? I'd like to avoid all of this amp & wiring stuff.

[Autobot]

Originally Posted by rubber_ducky

Did I read in here that earthquake are coming out with 2ohm versions of these subs? If so, these will be drop-in replacements for the OE subs? I'd like to avoid all of this amp & wiring stuff.

You did, but as of today they still are not out

[Atsnow]

Originally Posted by rubber_ducky

Did I read in here that earthquake are coming out with 2ohm versions of these subs? If so, these will be drop-in replacements for the OE subs? I'd like to avoid all of this amp & wiring stuff.

They are comming out with the 2 Ohms version but;

They will be direct replacement for non Logic7 system only as Logic7 use 4 Ohm speakers

When I did my install I tried running the SWS-8s out of the OEM amp and the improvement was only marginal , Knowing that the Logic7 puts out 30W more power per channel I doubt that you will see much improvement IMHO

[dejav0o]

Could someone help clarify how the amp wires up to the sub? I know the OP decided to run his own wires from the sub to the amp, but is it possible to just use the stock wires so I don't need to bother finding somewhere to tuck all that wiring in?

Also if that is true, how do we get the stock sub wires to make the subs go in parallel? From the numerous threads I've read, it sounds like the stock amp has 2 channels (1 for each sub). So to make a parallel setup with an aftermarket amp, will I just need to locate both the sub wires (under the back seats?), cut them off, and attach both positives together into the new amp, and same with the negatives?