[ctuna]

That is a static resistance measurement
not a manufacturer impedence measurement.

[Ao1]

Thanks to all for the help. I'm happy with the mid bass. Its the low end bass I'm missing. It sounds like I need to forget an under seat upgrade and go for a true subwoofer in the rear.

[rambca]

Yeah. I have upgraded underseat woofers and they pack a punch but it's simply not possible to produce the same impactful deep, deep, lows you can with a dedicated trunk-mounted subwoofer.

[Kevin_The_Clean1]

Originally Posted by ctuna

That is a static resistance measurement
not a manufacturer impedence measurement.

Hey ctuna. I have a question for you since you seem to be a knowledgable guru in audio related discussions. I know a little but I'm far from what you guys know about the E90 audio system. And hopefully this is relatively relevant enough & not far off topic. If so please forgive me (it's my 1st day here).


I have a 2011 335i sedan with the HK factory audio upgrade package. I just got done with a Bav Sound Stage-1 upgrade. It was simple to install & this car is my daily driver so it just needed to be an improvement (over the harsh factory drivers). Not a full audio overhaul with numerous separates from different manufacturers like you pros have done.


My question to you is about the ohm rating for a speaker & the "actual" rating you get once you measure it with a (digital multimeter). Long sort short, I ordered some ghost under-seat drivers from Bav Sound [in which they have 8, 4, & 2 ohm versions available). And they are a very small company so I didn't get to elect which ohm rating I needed for my car when I placed the online order. But once they shipped out & I saw they sent me a set of 8 ohms under seat subs, I already new (before I even installed them) that i wasn't going to get much output / sound from them. As it turns out my factory L7 under seat subs measure at 2.4 ohms. So… should Bav Sound be sending me a 4 ohm pair or a 2 ohm pair… ?


The official BMW documentation says (7x40 watts) @ 2 ohms & (2x70 watts) @ 4 ohms (for the Premium Hi-Fi). But again, I measure the factory subs & got 2.4 ohms & the 8 ohm set that Bav Sound sent me measured at 6.7 ohms. So… if the is true the designated ohm rating for most speakers is going to be considerably higher then it's actually rating.


Please help me out by shedding some light on this offering some accurate insight so that I can get this matter with them resolved quickly. Sorry in advance for this long post. And thank you…

[kaigoss69]

Let me take this one tuna...

I believe they (BSW) are making a mistake. The factory L7 woofers in e-series cars are 4 ohm. I saw some install reports of others with 4-ohm factory woofer systems installing what seemed to be 8-ohm Ghost speakers (designation "8O" in the model number on the back of the speaker). I then went through their checkout three days ago with my car (e90, L7), and the subs the website selected were "8 ohm". I immediately pointed this out to Bavsound on another thread, but have not seen a response (even though they responded to other questions in that same thread).

I am guessing they are scrambling right now trying to figure out how many wrong models they sent out. Yours is one of them unfortunately...

Originally Posted by Kevin_The_Clean1

Hey ctuna. I have a question for you since you seem to be a knowledgable guru in audio related discussions. I know a little but I'm far from what you guys know about the E90 audio system. And hopefully this is relatively relevant enough & not far off topic. If so please forgive me (it's my 1st day here).


I have a 2011 335i sedan with the HK factory audio upgrade package. I just got done with a Bav Sound Stage-1 upgrade. It was simple to install & this car is my daily driver so it just needed to be an improvement (over the harsh factory drivers). Not a full audio overhaul with numerous separates from different manufacturers like you pros have done.


My question to you is about the ohm rating for a speaker & the "actual" rating you get once you measure it with a (digital multimeter). Long sort short, I ordered some ghost under-seat drivers from Bav Sound [in which they have 8, 4, & 2 ohm versions available). And they are a very small company so I didn't get to elect which ohm rating I needed for my car when I placed the online order. But once they shipped out & I saw they sent me a set of 8 ohms under seat subs, I already new (before I even installed them) that i wasn't going to get much output / sound from them. As it turns out my factory L7 under seat subs measure at 2.4 ohms. So… should Bav Sound be sending me a 4 ohm pair or a 2 ohm pair… ?


The official BMW documentation says (7x40 watts) @ 2 ohms & (2x70 watts) @ 4 ohms (for the Premium Hi-Fi). But again, I measure the factory subs & got 2.4 ohms & the 8 ohm set that Bav Sound sent me measured at 6.7 ohms. So… if the is true the designated ohm rating for most speakers is going to be considerably higher then it's actually rating.


Please help me out by shedding some light on this offering some accurate insight so that I can get this matter with them resolved quickly. Sorry in advance for this long post. And thank you…

[ctuna]

You can't go by the static resistance alone since its
and impedance rating and not a resistance rating.

Since they are making these in multiple values they should
have sent you the right one based upon which stock system
you have.

I think they should have matched the impedance of whatever system
you have. (Assuming you are still using the stock amp 2 ohms)

If you got 8 or 4 I think it would cut your volume a lot.

[Kevin_The_Clean1]

Originally Posted by kaigoss69

Let me take this one tuna...

I believe they (BSW) are making a mistake. The factory L7 woofers in e-series cars are 4 ohm. I saw some install reports of others with 4-ohm factory woofer systems installing what seemed to be 8-ohm Ghost speakers (designation "8O" in the model number on the back of the speaker). I then went through their checkout three days ago with my car (e90, L7), and the subs the website selected were "8 ohm". I immediately pointed this out to Bavsound on another thread, but have not seen a response (even though they responded to other questions in that same thread).

I am guessing they are scrambling right now trying to figure out how many wrong models they sent out. Yours is one of them unfortunately...

Thank you. The owner left me a voicemail indicating the error on their part & they have realized all this after the fact that. But they are stepping up to the plate & at least taking ownership for the problem in assuming all or most cars where simply 8 ohm. Even my home speakers are 4 ohm (large Cerwin Vega CVS 215's). So they are shipping new units out promptly to us. They surely are going to go through some growing pains & headaches though until they can organize & get the right subs out to cars on the first order. As you can imagine it's kind of frustrating to say the least.

Originally Posted by ctuna

You can't go by the static resistance alone since its
and impedance rating and not a resistance rating.

Since they are making these in multiple values they should
have sent you the right one based upon which stock system
you have.

I think they should have matched the impedance of whatever system
you have. (Assuming you are still using the stock amp 2 ohms)

If you got 8 or 4 I think it would cut your volume a lot.

Thank you as well man. If the (Bav Sound) 8 ohms drivers were measured at 6.6 actual ohms I just didn't want their 2 ohm units to be well below the designated ohm class as well. From the information I've gathered from my 2011 E90 with the HK option, it sounds like all channels are at 2 ohms. Even though the official BMW literature says the 2 sub woofers channels are running at 4 ohms.

Simply want to make sure the factory L7 amp has enough dynamic headroom the play those 2 subs cleanly & efficiently. The factory under seat subs were measured at 2.4 ohms. So I hope their 2 ohm subs don't have an actual impedance measurement well below that like their others have displayed. Hopefully what I'm trying to say & get across makes sense…

[kaigoss69]

Originally Posted by Kevin_The_Clean1

Thank you. The owner left me a voicemail indicating the error on their part & they have realized all this after the fact that. But they are stepping up to the plate & at least taking ownership for the problem in assuming all or most cars where simply 8 ohm. Even my home speakers are 4 ohm (large Cerwin Vega CVS 215's). So they are shipping new units out promptly to us. They surely are going to go through some growing pains & headaches though until they can organize & get the right subs out to cars on the first order. As you can imagine it's kind of frustrating to say the least.

Thank you as well man. If the (Bav Sound) 8 ohms drivers were measured at 6.6 actual ohms I just didn't want their 2 ohm units to be well below the designated ohm class as well. From the information I've gathered from my 2011 E90 with the HK option, it sounds like all channels are at 2 ohms. Even though the official BMW literature says the 2 sub woofers channels are running at 4 ohms.

Simply want to make sure the factory L7 amp has enough dynamic headroom the play those 2 subs cleanly & efficiently. The factory under seat subs were measured at 2.4 ohms. So I hope their 2 ohm subs don't have an actual impedance measurement well below that like their others have displayed. Hopefully what I'm trying to say & get across makes sense…

DO NOT GET 2 OHM SUBS! You need 4 ohm.

[Kevin_The_Clean1]

Originally Posted by kaigoss69

DO NOT GET 2 OHM SUBS! You need 4 ohm.

That's exactly what I was thinking as well. However, it looks like they're are going to send me out a pair of 2 ohm under seat drivers.

If a 4 ohm driver really rests at close to 3.6 ohms & the factory drivers were measured at 2.4 - 2.6 ohms (the the closest match would be the 2 ohm). Right… ? Bav Sound says their 2 ohm under seat subs rest at exactly 2 ohms flat. So I don't think there should be any problems or large issues that will arise. There should be more efficiency at low to mid volumes which will provide a little more kick (low end response) while not upsetting the amp load or generating substantial more heat.

From what I've been told in appears my amps is running at 2 ohm even though the BMW documentation states the under seat subs are 4 ohm.

[kaigoss69]

Originally Posted by Kevin_The_Clean1

That's exactly what I was thinking as well. However, it looks like they're are going to send me out a pair of 2 ohm under seat drivers.

If a 4 ohm driver really rests at close to 3.6 ohms & the factory drivers were measured at 2.4 - 2.6 ohms (the the closest match would be the 2 ohm). Right… ? Bav Sound says their 2 ohm under seat subs rest at exactly 2 ohms flat. So I don't think there should be any problems or large issues that will arise. There should be more efficiency at low to mid volumes which will provide a little more kick (low end response) while not upsetting the amp load or generating substantial more heat.

From what I've been told in appears my amps is running at 2 ohm even though the BMW documentation states the under seat subs are 4 ohm.

Look, it has already been pointed out to you that impedance and resistance are two different things. The load the amplifier sees playing music is impedance and you cannot compare it with volt meter measurement. I will tell you that normally 4 ohm rated speakers will have a VC resistance of around 3.0 - 3.4 ohms, but thatb there are plenty of 4 ohm rated speakers out there that have a VC resistance of less than 3 ohms. In the end, you do what you want but consider yourself warned. I just can't believe BSW is sending you the WRONG impedance speakers for the second time...at least they should know better.

[Kevin_The_Clean1]

Originally Posted by kaigoss69

Look, it has already been pointed out to you that impedance and resistance are two different things. The load the amplifier sees playing music is impedance and you cannot compare it with volt meter measurement. I will tell you that normally 4 ohm rated speakers will have a VC resistance of around 3.0 - 3.4 ohms, but thatb there are plenty of 4 ohm rated speakers out there that have a VC resistance of less than 3 ohms. In the end, you do what you want but consider yourself warned. I just can't believe BSW is sending you the WRONG impedance speakers for the second time...at least they should know better.

Fully understood & I'm not trying to test anyones patience here. Simply making sure to get this matter resolved & the issue properly fixed. I can't believe it either & that was the reason I wanted to run this by a few seasoned professionals in E90 audio arena. I will speak to him tomorrow (they are a small company & hard to get old of anyone in person) to discuss this issue.

My factory under seat drivers rest at 2.4 ohms & the new BSW drivers rest at 2 ohms flat, so it appeared that they would work best. But I guess the BSW 4 ohms drivers will be ideal for my E90 HK audio system with factory amps.

I appreciate your help & thank you for explaining this to me.

[kaigoss69]

Originally Posted by Kevin_The_Clean1

Fully understood & I'm not trying to test anyones patience here. Simply making sure to get this matter resolved & the issue properly fixed. I can't believe it either & that was the reason I wanted to run this by a few seasoned professionals in E90 audio arena. I will speak to him tomorrow (they are a small company & hard to get old of anyone in person) to discuss this issue.

My factory under seat drivers rest at 2.4 ohms & the new BSW drivers rest at 2 ohms flat, so it appeared that they would work best. But I guess the BSW 4 ohms drivers will be ideal for my E90 HK audio system with factory amps.

I appreciate your help & thank you for explaining this to me.

You cannot take the static resistance measurement as an absolute factor for determining the amp load. You must go by the rated impedance and the L7 amp is only rated for 4 ohms. With 2 ohm woofers hooked up, the amp would try to push nearly double the power it is rated for and that would probably not be a good thing, especially given the cost of the amp.

[Kevin_The_Clean1]

Originally Posted by kaigoss69

You cannot take the static resistance measurement as an absolute factor for determining the amp load. You must go by the rated impedance and the L7 amp is only rated for 4 ohms. With 2 ohm woofers hooked up, the amp would try to push nearly double the power it is rated for and that would probably not be a good thing, especially given the cost of the amp.

I absolutely agree & greatly appreciate your input. The last thing I want to do is shorten the life of the factory amp because they sent me out 2 ohm drivers. Hopefully I can get this resolved quickly & I'm glad you were able to shed some light on this for me since BSW has dropped the ball a little bit.

[kaigoss69]

Glad I was able to guide you towards the light!

[ctuna]

http://www.e90post.com/forums/attach...2&d=1266451970

[Kevin_The_Clean1]

Originally Posted by ctuna

http://www.e90post.com/forums/attach...2&d=1266451970

Thank you tuna. I've already viewed that BMW OEM audio system PDF. But I still appreciate the help. And that's why I didn't understand why the factory amp was running at 4 ohm (for the two under seat channels) & yet the factory L7 (under seat) drivers measured at 2.4 ohm with my digital multimeter. Because those drivers are running at close to 2 ohms (depute the amp playing at 4 ohms). I know realize the standing resistance of the speakers is different then what the amp plays & stays happy at. Now maybe you can see what I was a bit perplexed & may have appeared to be asking rookie type questions.

[bin01123]

Thank you for this thread. I was planning to upgrade my subs under the seat to Logic 7 but now I know my Bimmertech amp won't have enough power for it. I'll save my money and just work with what I've got. Thanks again for sharing this information folks

[shanes]

Thanks for this thread. I also have a 2011 e90 with Logic 7 HK and just received and installed my 8 ohm Bavsound under seats, and immediately was displeased at how low they sound. Upon seeing this thread and seeing that 4 ohm is what's really best for the HK system, I decided to call Bavsound.. I'm told they are the correct woofers and to give them time to break in.. anyone ever get the 4 ohm version installed in a L7 car, and how are the results?

[kiteboy]

Hi, i’ve changed my 6 hps basic stereo to 10 combined in my bmw e92.

I put for front 2 new mediums individual and add tweeters, and i confirm it is 4 ohm.

Under each seat i put new sub logic 7 already in 4 ohms.

For rear medium hi-fi with tweeters harman kardon.

I also add external ampli mosconi gladen one 120.4 DSP