[coloradoe92m3]

Anyone know how much power is sent to OEM woofers in Dirac system with the 825w amp??

[Technic]

Originally Posted by coloradoe92m3

Anyone know how much power is sent to OEM woofers in Dirac system with the 825w amp??

75W x 7 (4ohms) and 150W x 2 (7ohms) = 825W

[coloradoe92m3]

Originally Posted by Technic

75W x 7 (4ohms) and 150W x 2 (7ohms) = 825W

Damn for an OEM system that's super. If only they used a 4 ohm woofer this thing would really rock.

I still don't get when every amp in the world can play a 4 ohm speaker, our amp can't play a 4 ohm woofer??? 7 is ridiculous. So really its like 75 watts to each woofer in a 4 ohm. I'm tempted to stick jehneets and just power them with stock setup. 4 ohmss should be fine

[coloradoe92m3]

Originally Posted by coloradoe92m3

Damn for an OEM system that's super. If only they used a 4 ohm woofer this thing would really rock.

I still don't get when every amp in the world can play a 4 ohm speaker, our amp can't play a 4 ohm woofer??? 7 is ridiculous. So really its like 75 watts to each woofer in a 4 ohm. I'm tempted to stick jehneets and just power them with stock setup. 4 ohmss should be fine

Swamp was just realizing the Dirac amp clearly runs 16 4 ohm speakers so why would it have any problem driving 2 4,ohm woofers like jehnerts or sws 4ohm etc.

If it can't than how? Never seen an amp have some channels for different ohms?
.
To be clear, Dirac 7 ohm woofers are really only seeing 75 watts roughly due to that 7 ohm impedance? I think 100-150 watts would be perfect if you had 4 ohms,?

Maybe I'll do this experiment and lost results as don't see anyone tried jehnerts hooked to stock Dirac amp.

Last question, is there a way to add a passive filter for the OEM woofers to eliminate 40hz and below? Any easy crossover or something? Really the only problem system has is when it reaches for subbass notes and distorts.

[Technic]

Originally Posted by coloradoe92m3

Damn for an OEM system that's super. If only they used a 4 ohm woofer this thing would really rock.

I still don't get when every amp in the world can play a 4 ohm speaker, our amp can't play a 4 ohm woofer??? 7 is ridiculous. So really its like 75 watts to each woofer in a 4 ohm. I'm tempted to stick jehneets and just power them with stock setup. 4 ohmss should be fine

The DIRAC OEM amp woofer outputs are not stable at 4ohms.

Please search for details, this has been discussed before.

[bmw325i]

Originally Posted by coloradoe92m3

Damn for an OEM system that's super. If only they used a 4 ohm woofer this thing would really rock.

I still don't get when every amp in the world can play a 4 ohm speaker, our amp can't play a 4 ohm woofer??? 7 is ridiculous. So really its like 75 watts to each woofer in a 4 ohm. I'm tempted to stick jehneets and just power them with stock setup. 4 ohmss should be fine

Half the impedance is double the power. At 4 ohms the stock amp would try to put out 300 watts per channel for the subs. Like Technic said the amp isn't designed for 4 ohms. It would probably clip.

[coloradoe92m3]

That's my point and I did search. It runs every other speaker at 4ohms . All 16. So that isn't 4 ohm stable? If all speakers were 7 ohm then of course I see why it wouldn't work

[kaigoss69]

Originally Posted by coloradoe92m3

That's my point and I did search. It runs every other speaker at 4ohms . All 16. So that isn't 4 ohm stable? If all speakers were 7 ohm then of course I see why it wouldn't work

Look, you have been told that the amp is not stable at 4 ohms. Why can't you accept that? Whatever the reason was to design it that way, we don't know, and it doesn't matter. Fact is that the amp will try to put out close to double the power at 4 ohms. If you want to install 4 ohm speakers anyway, go ahead, we can't stop you. Just don't come back here complaining when the dealer charges you over $1000 to replace a fried amp...

[bmw325i]

Originally Posted by kaigoss69

Look, you have been told that the amp is not stable at 4 ohms. Why can't you accept that? Whatever the reason was to design it that way, we don't know, and it doesn't matter. Fact is that the amp will try to put out close to double the power at 4 ohms. If you want to install 4 ohm speakers anyway, go ahead, we can't stop you. Just don't come back here complaining when the dealer charges you over $1000 to replace a fried amp...

I've seen people wire 4-8 subwoofers in parallel to a bridged 2 channel amp.

[coloradoe92m3]

Originally Posted by kaigoss69

Look, you have been told that the amp is not stable at 4 ohms. Why can't you accept that? Whatever the reason was to design it that way, we don't know, and it doesn't matter. Fact is that the amp will try to put out close to double the power at 4 ohms. If you want to install 4 ohm speakers anyway, go ahead, we can't stop you. Just don't come back here complaining when the dealer charges you over $1000 to replace a fried amp...

OK for us idiots than educate me as I honestly don't understand being unstable at 4 ohms when the 14 other speakers in the same system are all 4 ohm speakers! If all speakers were 7 ohms than obviously I get it. I'm just trying to learn and understand. Telling someone to just accept something that doesn't make sense seems not in spirit of trying to help people learn.
.if its 4 ohm unstable than why does it push 14 4 ohm speakers?

[bmw325i]

Originally Posted by coloradoe92m3

OK for us idiots than educate me as I honestly don't understand being unstable at 4 ohms when the 14 other speakers in the same system are all 4 ohm speakers! If all speakers were 7 ohms than obviously I get it. I'm just trying to learn and understand. Telling someone to just accept something that doesn't make sense seems not in spirit of trying to help people learn.
.if its 4 ohm unstable than why does it push 14 4 ohm speakers?

Because if it was stable at 4 ohms on the sub channels don't you think they would have used 4 ohm subs to utilize nearly twice as much power? By cutting the impedance in half you are also doubling the amperage. Maybe it would work and be alright, but there is no way to know for sure since you are wanting to use the amp in a way it wasn't designed to be used.

[coloradoe92m3]

Show me one other amp with varying stability of its channels? I can't find one. So to make it seem so obvious is a bit rude. Its rare to me to have 7 channels 4 ohm stable and 2 only 7 ohm stable. I don't even know how that's technically possible. Clearly it is but its not a no brainer

[kaigoss69]

Originally Posted by coloradoe92m3

OK for us idiots than educate me as I honestly don't understand being unstable at 4 ohms when the 14 other speakers in the same system are all 4 ohm speakers! If all speakers were 7 ohms than obviously I get it. I'm just trying to learn and understand. Telling someone to just accept something that doesn't make sense seems not in spirit of trying to help people learn.
.if its 4 ohm unstable than why does it push 14 4 ohm speakers?

My best guess would be that internally the amp has 11 channels. 7 of them drive 4 ohm loads each. 4 of them are bridged into 2 channels. When you bridge amplifier channels (and the impedance of the speaker stays at 4 ohm), then the combined output of two channels doubles. So 75x2 = 150. 150W x 2 = 300W. So at 4 ohm, the two bridged channels will try to output 300W each, which the power supply cannot handle. Therefore, the speaker impedance was basically doubled, which results in about 150W per channel output, which makes the amp happy.

[bmw325i]

Originally Posted by coloradoe92m3

Show me one other amp with varying stability of its channels? I can't find one. So to make it seem so obvious is a bit rude. Its rare to me to have 7 channels 4 ohm stable and 2 only 7 ohm stable. I don't even know how that's technically possible. Clearly it is but its not a no brainer

Kaigoss's explanation seems logical. Stock amps are different than aftermarket amps. They are designed to work with the stock speakers. Maybe it would work as you are saying, but only the amp manufacturer would know that. Since the amp is only designed to work with the stock speakers there is no other info to go off of to know whether or not it can handle a lower impedance.

[coloradoe92m3]

Originally Posted by kaigoss69

My best guess would be that internally the amp has 11 channels. 7 of them drive 4 ohm loads each. 4 of them are bridged into 2 channels. When you bridge amplifier channels (and the impedance of the speaker stays at 4 ohm), then the combined output of two channels doubles. So 75x2 = 150. 150W x 2 = 300W. So at 4 ohm, the two bridged channels will try to output 300W each, which the power supply cannot handle. Therefore, the speaker impedance was basically doubled, which results in about 150W per channel output, which makes the amp happy.

OK that's making sense. With that said would 4 channels bridged to drive 2 7 ohm speakers give a true output of 150 watts at each 7 ohm driver vs not bridged the watts would essentially be half due to 7 ohms?

[Technic]

Originally Posted by coloradoe92m3

That's my point and I did search. It runs every other speaker at 4ohms . All 16. So that isn't 4 ohm stable? If all speakers were 7 ohm then of course I see why it wouldn't work

I really hate searching for forum members, I really do: http://www.m3post.com/forums/showthread.php?t=166476

[Technic]

Originally Posted by coloradoe92m3

OK for us idiots than educate me as I honestly don't understand being unstable at 4 ohms when the 14 other speakers in the same system are all 4 ohm speakers! If all speakers were 7 ohms than obviously I get it. I'm just trying to learn and understand. Telling someone to just accept something that doesn't make sense seems not in spirit of trying to help people learn.
.if its 4 ohm unstable than why does it push 14 4 ohm speakers?

Look at the OEM amp size. Then look at the fuse value protecting that OEM amp. Does that amp size and fuse value look like 825W?

BMW went for the lowest current draw technically possible. Something got to give, thus 7ohm woofers.

[coloradoe92m3]

So wait are you saying its not even really 825 watts?

And to clarify my above. If I got another amp is there benefit to running 250w-300 watts to each 7 ohm woofer? Based on most use 100-150 to drive 4 ohm 8 inch woofers. This would assume I didn't want to replace them or add a sub but just power them better

[coloradoe92m3]

Originally Posted by Technic

I really hate searching for forum members, I really do: http://www.m3post.com/forums/showthread.php?t=166476

Sorry but that link has nothing to do with what we are talking about.

[Technic]

Originally Posted by coloradoe92m3

Sorry but that link has nothing to do with what we are talking about.

Ok, I guess that you have problems reading as well.

Good luck.

[coloradoe92m3]

Again you take time to check this thread and belittle me. I'm just trying to learn man. I've read and read online and pieced together info largely to your helpful posts but you could have just spent 2 mins answering my questions instead of searching for kinks that don't address my question. I'll keep it to one easy one which would be helpful.
.1. Is the stock woofers going to benefit by ppweeing them separately with 250-300 watts each? Assuming they won't explode but from a sound quality aspect are they being relatively under powered with 150 watts each right now?

[bmw325i]

I don't see how you could say that thread isn't relevant.

Anyways it's not worth it to use the stock woofers since they are 7 ohm. To get 300 watts at 7 ohms you'd need an amp that can do 1000 watts rms at 2 ohms. You might as well replace the stock woofers and power them with an aftermarket amp or add a trunk sub.