[2008_335i_coupe]

I have a 2008 E92 with the Navigation and would like to add the SWS earthquake 8" subs.. which do I need the 2 or 4 ohm? I will be using the proper amp for them..

[VP Electricity]

Which impedance speakers you use in a situation like this dictate which impedance you choose. Which amp will you use?

[kmarei]

if you have the HIFI sound system
the 2 ohm is a better option so when its time to sell the car
you don't have to put the OEM woofers back
since the OEM are 2 ohm and you replace them with 2ohm
they can run off the OEM amp fine
that's what i did

[I335]

How do they sound with the OEM amp - noticeable improvement?

[VP Electricity]

They sound like ass - which is why his suggestion is, well, less than optimal? I mean, it's good you HAD a plan...

Buy what works for you and your amp NOW, and put factory back in later.

[kmarei]

Originally Posted by VP Electricity

They sound like ass - which is why his suggestion is, well, less than optimal? I mean, it's good you HAD a plan...

Buy what works for you and your amp NOW, and put factory back in later.

my suggestion was not to use the SWS-8 with the factory amp
i simply said when you are done with the car, when its time to sell or return the lease.
you would just put the OEM amp back and you can sell it that way
but not as an upgrade path for the current owner.
saving you the need to take out the seats again, the enclosures, reinstall the subs, mount the enclosures, and put the seats back.

plus they don't sound like ass, at worst they will sound as good as the OEM subs.
some people have said they put out more power in the lower frequencies than the OEM subs.
so you are not cheating the next owner


plus, FYI, the majority of amps can handle both 4 and 2 ohm stereo loads. so this is a non issue

[VP Electricity]

Most aftermarket amps will supply 80-100% more power into 2 ohms than into 4 ohms, so it's most certainly NOT a non-issue.

If you are using a mono channel it will probably only be 2 ohm stable, not 1 ohm stable.

When you parallel two 4 ohm woofers you have a 2 ohm load, which would be OK with those amps on the mono channel. Paralleling two 2 ohm woofers gives you a 1 ohm load... and mono amps are RARELY stable into 1 ohm. This applies to the PDX-5, probably the most common amp on this forum.

So it seems to be pretty germane...

[kmarei]

Originally Posted by VP Electricity

Most aftermarket amps will supply 80-100% more power into 2 ohms than into 4 ohms, so it's most certainly NOT a non-issue.

so getting more power out of an amp is a bad thing??

Originally Posted by VP Electricity

When you parallel two 4 ohm woofers you have a 2 ohm load, which would be OK with those amps on the mono channel. Paralleling two 2 ohm woofers gives you a 1 ohm load... and mono amps are RARELY stable into 1 ohm. This applies to the PDX-5, probably the most common amp on this forum.

um yeah but you connect 2x 2ohm woofers in series you get 4ohms
which any amp can handle
so you have a choice of 1ohm (parallel) or 4ohm (series)
if you get 2x 4ohm woofers you have a choice of 2 ohm or 8ohm
hardly a better option
i don't know of any car amp that can't handle a 4 ohm load
i know many that can't handle a 2 ohm load

plus in your example of the PDX-5, it puts out the same power into 4ohms as it does into 2 ohms
so in your example there would be no difference in using 4ohm woofers or 2 ohm woofers
except you'd have to replace the 4ohms with the OEM woofers if you ever put the OEM amp back
you wouldn't with the 2ohm woofers

[VP Electricity]

I think you're just mad now. I'm not trying to bag on you, just take a minute and read what I'm trying too get across.

I never said more power out of an amp was bad. But which amp?

f you put TWO 2-ohm woofers in parallel on a mono channel, you have ONE ohm. THe PDX-5 is NOT rated for one ohm. I don't know a 5-channel amp which is at the moment. The JL HD900/5 is only rated to 1.5 ohm.

So if you want to use a PDX5 OR a JL HD900/5 and use the mono channel for the SWS-8, you want two 4-ohm woofers.

But if you are using a nice 4-channel amp and running it in 4-channel mode, you want two 2 ohm drivers.

All I'm saying is, you choose the impedance based on the amplifier you will be running. Otherwise, why make multiple impedances?

[kmarei]

i'm not mad at all, you haven't insulted me
i respect your opinion, which is why i am surprised you would recommend the 4ohm SWS's

lets take the 4ohms
you can wire them in parallel to get 2ohm (works with about 70-80% of amps)
or in series to get 8ohm (unusable for any car amp)

let's take the 2ohms
you can wire them in parallel to get 1ohm (not recommended for most Class D amps, such as the PDX and HD900) or in series to get 4ohm

now this is why i am surprised at your opinion
4ohm is the standard when it comes to car audio
i don't know of any amp made in the last 20 years that won't work with 4ohm
so why not get the option that gives you 4ohms to work with?
namely the 2 2ohm woofers in series

so basically with 2 or 4ohm woofers
you only have one option on how to wire them
parallel for 4ohm woofers
and series for 2ohm woofers

now since in both examples you used, the PDX and the HD900
you don't get any extra power on the amp with a 2ohm load, and you are putting under more stress due to the lower impediance, your amp will generate more heat into 2ohm than into 4ohm.
more heat and no extra power

that same amp driving 4ohm woofers in series, will put out the same power as the above example, while at the same time generating less heat, and in most amps i've seen, they are much more efficient into 4ohms than 2 ohm
so less heat and obviously, using less power
to give out the same watts

[Technic]

Originally Posted by kmarei

i'm not mad at all, you haven't insulted me
i respect your opinion, which is why i am surprised you would recommend the 4ohm SWS's

lets take the 4ohms
you can wire them in parallel to get 2ohm (works with about 70-80% of amps)
or in series to get 8ohm (unusable for any car amp)

let's take the 2ohms
you can wire them in parallel to get 1ohm (not recommended for most Class D amps, such as the PDX and HD900) or in series to get 4ohm

now this is why i am surprised at your opinion
4ohm is the standard when it comes to car audio
i don't know of any amp made in the last 20 years that won't work with 4ohm
so why not get the option that gives you 4ohms to work with?
namely the 2 2ohm woofers in series

so basically with 2 or 4ohm woofers
you only have one option on how to wire them
parallel for 4ohm woofers
and series for 2ohm woofers

now since in both examples you used, the PDX and the HD900
you don't get any extra power on the amp with a 2ohm load, and you are putting under more stress due to the lower impediance, your amp will generate more heat into 2ohm than into 4ohm.
more heat and no extra power

that same amp driving 4ohm woofers in series, will put out the same power as the above example, while at the same time generating less heat, and in most amps i've seen, they are much more efficient into 4ohms than 2 ohm
so less heat and obviously, using less power
to give out the same watts

What I get from VP post is that, most of the amps out there are stable at 2 ohms and put out more power at 2 ohms. Therefore, deciding between the 2 and the 4 ohms SWS-8 should be based on which amp is going to be used and the power output at those loads.

For example, if amp A put out 75W per channel at 4 ohms and 150W at 2 ohms, a 2 ohms SWS-8 would be a better choice as it will be receiving more power from the amp. But if amp B is not stable at 2 ohms then it will require a 4 ohm SWS-8, regardless of its power output.

Of course, if you go fancy with series/parallel wiring then you wll have more combinations and options. But then again, why?

Get the SWS-8 load that better matches the amp that you are using/going to use.

That's all.

[kmarei]

Originally Posted by Technic

What I get from VP post is that, most of the amps out there are stable at 2 ohms and put out more power at 2 ohms. Therefore, deciding between the 2 and the 4 ohms SWS-8 should be based on which amp is going to be used and the power output at those loads.

agreed
but based on the 2 examples he stated, which are popular with the upgrades done on our cars, on this forum at least, there is no advantage to having a 2ohm total load Vs 4ohm.
since both amps are Class D, they put out the same power into 4 or 2ohm
but if you hook them up with a 2ohm load, they will generate more heat, which is a potential problem if mounted under the trunk trim, or where the cd changer goes. So in these examples, it's better, cooler, and more efficient to use 2ohm subs wired in series, than 4 ohm woofers in parallel.

if you use 2ohmn woofers wired in series for a 4ohm load you will get 300w from the amp
but if you use 4ohm woofers (VPs suggestion) in parallel (2ohm load) with the pdx-5 you will get the same 300watts, but your amp will run hotter and use more power.

Originally Posted by Technic

For example, if amp A put out 75W per channel at 4 ohms and 150W at 2 ohms, a 2 ohms SWS-8 would be a better choice as it will be receiving more power from the amp. But if amp B is not stable at 2 ohms then it will require a 4 ohm SWS-8, regardless of its power output.

agreed, this is always the case with Class AB amps
not Class D, which are becoming more and more popular, unfortunately
i think your case holds if you are using a 6 channel amp
better to use 4 ohm subwoofers than 2ohm

Originally Posted by Technic

Of course, if you go fancy with series/parallel wiring then you wll have more combinations and options. But then again, why?

well is it that much harder to wire your 2 subs in series Vs parallel?
you do it once and forget it after that
you just hook up minus from one woofer and plus from the other to the amp
and link the other 2 wires. that's it


i have the freedom to use anything from, 8 ohm down to 1/4 ohm, so i am spoilt for choice
you can't beat old school amps
i still think they sound better than the newer stuff

[mathu.bala]

IMO having 2 ohm is better since all amps will do better at 2 ohm. I'm looking to buy 2 ohm sws-8 myself.