I've got a odd question, which I am sure will draw up many answers, but how loud should the sub hit in a e39 540i? The reason I am asking is because I know that the e39 540 is well sealed and that you don't get the kind of sound you would get in a car such as a Civic Hatchback.

I've installed a 12" JL 12W6 with an Alpine M650 Single Channel Amp, and I just don't think that it is hitting hard enough. I am wondering if I tapped into the incorrect wires, or something??

I've removed the Nokia box so I have the holes in the top that are coming into the cabin and I would expect to be getting more bass/thump then I am getting.

I am trying to see what you guys think, or maybe if you think that I hooked it up wrong? I am using a LOC rather than high level inputs which the amp has as well....

what do you think?

I am also going to be posting this is then 5 series section....

you should not be using the LOC unless you put it after the amp. That amp and woofer should hit pretty hard. If its dual voice coil, it might be wired wrong. there are many variables that would make it under perform.

As the man said, unless you hooked it up wrong, you should be all set.

Regardless of where you tapped into the signal you should be using your amps high level inputs. LOC's are only used in the case of a high level signal and an amp with low level inputs.

Do you have DSP? If so, the wires you tapped into after the amp should have been in the same harness as the power wire.

d-

LOC's are only used in the case of a high level signal and an amp with low level inputs.


Thats incorrect. The ONLY time you use the hi-level inputs on an amplifier in a BMW is if the amplifier is capable of accepting a balanced input (that is if you're tapping into the system before the factory amp). If tapping into the system after the factory amp, I REALLY hope you have a GOOD LOC, as there is alot of wattage coming out of the factory amp, especially the DSP amp.

To the OP:

What LOC are you using, and what system does your vehicle have, DSP, or non-DSP?? Where did you make your connections for your LOC? Have you adjusted the gains on the LOC if it has any?

Well I got everything working correctly this weekend with a buddy on mine. Not sure if it was the fact that the LOC was a passive LOC rather than an active LOC. We ended up using the Speaker Level Inputs on the Amp itself (Alpine amp) and the sub sounds awesome now, exactly what I was expecting. A ton of bass comes into the cabin and just sounds awesome.

Now I just got to dynamat the trunk in a few particular spots, so it doesn't rattle so much. That should be the next challenge.

Thanks for everyones help, and especially Jason as BSW!

~Andy

Thats incorrect. The ONLY time you use the hi-level inputs on an amplifier in a BMW is if the amplifier is capable of accepting a balanced input (that is if you're tapping into the system before the factory amp). If tapping into the system after the factory amp, I REALLY hope you have a GOOD LOC, as there is alot of wattage coming out of the factory amp, especially the DSP amp.
...

No offense Kendogg, but you are wrong on all accounts.

First, by definition, all high level inputs are balanced. A balanced input is one that has signal on both wires (for example: the leads to your speakers) instead of a signal and a reference (for example: typical home RCA's).

Second, there is not "alot (sic) of wattage coming out of the factory amp, especially the DSP amp". Even the M-Audio amp, which is at the high end of the DSP amps is no more than 50W per channel (to the subs, about 15W otherwise) at a relatively high distortion. The rest of them have less power as the subs are smaller or non-existent.

d-

Well I got everything working correctly this weekend with a buddy on mine. Not sure if it was the fact that the LOC was a passive LOC rather than an active LOC. We ended up using the Speaker Level Inputs on the Amp itself (Alpine amp) and the sub sounds awesome now, exactly what I was expecting. A ton of bass comes into the cabin and just sounds awesome.

Now I just got to dynamat the trunk in a few particular spots, so it doesn't rattle so much. That should be the next challenge.

Thanks for everyones help, and especially Jason as BSW!

~Andy

Glad you got it working...

d-

No offense Kendogg, but you are wrong on all accounts.

First, by definition, all high level inputs are balanced. A balanced input is one that has signal on both wires (for example: the leads to your speakers) instead of a signal and a reference (for example: typical home RCA's).

Second, there is not "alot (sic) of wattage coming out of the factory amp, especially the DSP amp". Even the M-Audio amp, which is at the high end of the DSP amps is no more than 50W per channel (to the subs, about 15W otherwise) at a relatively high distortion. The rest of them have less power as the subs are smaller or non-existent.

d-

No, all high level inputs are not balanced. Inputs in and of themselves cannot be balanced, only the signal being fed to them. BMW's use a balanced output from the factory head unit to the factory amp. Most factory, and aftermarket even, headunits do not.

http://www.bcae1.com/

Follow the pathway on the right side of the page down to number number 119 - Balanced Line Drivers. It's a basic understanding of the concept of balanced vs. unbalanced signals, and their purposes, in car audio.

There is more wattage than most LOC's are rated for coming out of the DSP amp. Not all that many LOC's are rated higher than 25-30 watts rms, regardless of the THD. DSP equipped vehicles have 40-50 watts per channel to the interior speakers. Yes, you are correct though, that it is at a fairly high THD, but again, the LOC doesn't care how much distortion is in the signal, it only knows that it's being fed x amount of power.

No, all high level inputs are not balanced. Inputs in and of themselves cannot be balanced, only the signal being fed to them. BMW's use a balanced output from the factory head unit to the factory amp. Most factory, and aftermarket even, headunits do not.

http://www.bcae1.com/

Follow the pathway on the right side of the page down to number number 119 - Balanced Line Drivers. It's a basic understanding of the concept of balanced vs. unbalanced signals, and their purposes, in car audio.


First, I've read the website in nearly it's entirety as it relates to car audio.

Leaving that on the side, let's go back to the paradox that you've just created:

1. The High (Speaker) Level input on an amplifier is intended to accept a speaker level output from a headunit or amplifier.
2. You indicate that an LOC should be used instead because the BMW headunit provides a balanced output.
3. LOC's, by definition, take a speaker level input and convert it to a low level output.

So you are telling him that the speaker level converter on his amplifier will not work (because of balanced signals) but that instead he needs to use a speaker level converter (because of balanced signals)...

See the issue with the logic? The bottom line is that a Speaker level input stage on an amplifier is the same as the one on the LOC, so either they both work with balanced signals or neither one does. I maintain that they both do, so don't waste money on an LOC.

There is more wattage than most LOC's are rated for coming out of the DSP amp. Not all that many LOC's are rated higher than 25-30 watts rms, regardless of the THD. DSP equipped vehicles have 40-50 watts per channel to the interior speakers. Yes, you are correct though, that it is at a fairly high THD, but again, the LOC doesn't care how much distortion is in the signal, it only knows that it's being fed x amount of power.

I rechecked my numbers - agreed that the wattages are in the 40W range. Never seen a rating on an LOC, but I haven't used many either, so maybe I just didn't notice...

d-

First, I've read the website in nearly it's entirety as it relates to car audio.

Leaving that on the side, let's go back to the paradox that you've just created:

1. The High (Speaker) Level input on an amplifier is intended to accept a speaker level output from a headunit or amplifier.
2. You indicate that an LOC should be used instead because the BMW headunit provides a balanced output.
3. LOC's, by definition, take a speaker level input and convert it to a low level output.

So you are telling him that the speaker level converter on his amplifier will not work (because of balanced signals) but that instead he needs to use a speaker level converter (because of balanced signals)...

See the issue with the logic? The bottom line is that a Speaker level input stage on an amplifier is the same as the one on the LOC, so either they both work with balanced signals or neither one does. I maintain that they both do, so don't waste money on an LOC.



I rechecked my numbers - agreed that the wattages are in the 40W range. Never seen a rating on an LOC, but I haven't used many either, so maybe I just didn't notice...

d-


I missed the part where the OP said his amp is an Alpine amp, thats my bad. The alpines are specifically listed to be rated to handle balanced inputs, whereas most amplifiers are not. Try running a cheap branded amplifier with speaker-level inputs in your BMW and tell me what happens to the input stages. Go check out the Mini boards and see how many people there have cooked input stages in amplifiers not rated for balanced inputs.

You seem to not understand how LOC's work, nor how amplifier input sections work as well. Most LOC's, when taking in the input signal, negate whatever signal is on the negative side, using only the positive wire's signal - now creating an unbalanced signal to run thru an RCA cable into an amplifier.

To the OP - Mr. Baker obviously doesn't have much experience with many amplifiers on the market, especially anything that might not be considered 'top end', as most amplifiers are NOT rated for balanced inputs, and may very well burn up input stages due to being fed a balanced input signal that they are not designed for. I'm not an engineer, but I d have a good friend who is an audio engineer that I'd be glad to show this post to to see if he could write a quick post for me to prove him wrong as well. If you'd like to try using spaker level inputs on a cheaper amp from a BMW head unit - by all means, go for it, and tell me how well your amp works in ~6 months.

You seem to not understand how LOC's work, nor how amplifier input sections work as well. Most LOC's, when taking in the input signal, negate whatever signal is on the negative side, using only the positive wire's signal - now creating an unbalanced signal to run thru an RCA cable into an amplifier.

This is good information, but it still doesn't explain how the high level input of an amplifier is different from the high level input of an LOC and why one is more suitable than the other!

And don't try to hide behind "I missed the part where the OP said his amp is an Alpine amp" - that is irrelevant to this discussion. As a side note, I don't deal with high end components, I tend to deal with lower end but I make sure I know what I'm doing so I don't have any problems.

You specifically contradicted something I said. I called you on it and asked you to back it up, and your responses so far have either been a) contradictory, or b) have consisted of simply stating that I am wrong and you are right.

I've provided clear, logical information and even walked through it in simple terms - if you can't do the same and must resort to insults then I'm sure the OP can decide who does / doesn't know what they are talking about...

d-

I'm not an engineer, but I d have a good friend who is an audio engineer that I'd be glad to show this post to to see if he could write a quick post for me to prove him wrong as well.

I'll be waiting eagerly with 'bated breathe for your good friend to arrive and explain why balanced inputs won't burn up LOC's but will burn up the high level inputs of an amplifier.

d-

I'll be waiting eagerly with 'bated breathe for your good friend to arrive and explain why balanced inputs won't burn up LOC's but will burn up the high level inputs of an amplifier.

d-

http://www.createforum.com/petereuro/viewtopic.php?p=1816&mforum=petereuro#181

I've gone ahead and posted this here for discussion. I've never stated I'm the most intelligent person in the world, but I have TONS of experience working on these cars, and know what I've seen and done. I'm not going to sit here and debate with you what is compatible with a BMW and what isn't.

http://www.createforum.com/petereuro/viewtopic.php?p=1816&mforum=petereuro#181

I've gone ahead and posted this here for discussion. I've never stated I'm the most intelligent person in the world, but I have TONS of experience working on these cars, and know what I've seen and done. I'm not going to sit here and debate with you what is compatible with a BMW and what isn't.

I've asked one follow up question over there since the responses seem to be centered on RCA's vs. speaker level inputs.

For the record, I fully agree that if you take a balanced signal and provide it to either a) an RCA low level input not capable of handling balanced signals or b) any input not capable of handling ~10V inputs (2x the ~5V signal BMW uses) you are likely to cause serious damage to the amplifier input stage.

d-

I've asked one follow up question over there since the responses seem to be centered on RCA's vs. speaker level inputs.

For the record, I fully agree that if you take a balanced signal and provide it to either a) an RCA low level input not capable of handling balanced signals or b) any input not capable of handling ~10V inputs (2x the ~5V signal BMW uses) you are likely to cause serious damage to the amplifier input stage.

d-

Douglas, perhaps that may be where my misunderstanding of how the circuitry resides. I posted the question there as it's a small board, and there are a few highly intelligent people posting there (peter is the creator of the forum). From what I'm gathering, especially from Thy's posts, is that it may be more an issue with the voltage level from the factory head unit rather than the fact that it is a balanced signal.

However - Douglas, I do wish to apologize for my late-night ramblings. Unfortunately, I've taken the stance on the subject in which I do have much experience, but unfortunately don't have the technical knowledge in circuitry design to be able to backup my claims.

Douglas, perhaps that may be where my misunderstanding of how the circuitry resides. I posted the question there as it's a small board, and there are a few highly intelligent people posting there (peter is the creator of the forum). From what I'm gathering, especially from Thy's posts, is that it may be more an issue with the voltage level from the factory head unit rather than the fact that it is a balanced signal.

However - Douglas, I do wish to apologize for my late-night ramblings. Unfortunately, I've taken the stance on the subject in which I do have much experience, but unfortunately don't have the technical knowledge in circuitry design to be able to backup my claims.

Ken,

Call me Doug - only my mom calls me Douglas and that's only when she's mad :) (DougBaker wasn't available...)

The BMW system is quite unusual in the voltage level at which the radio communicates to the amplifier. +-5V is quite a strong system, and actually a very good idea when it comes to car audio given how noisy most car power is.

I'm no expert on audio circuit design, but I do have a strong working knowledge of the BMW E39 audio systems from a) online research, and b) removing my own DSP system (http://www.m5board.com/vbulletin/blog.php?u=25709)and converting it to aftermarket components.

The number one issue I found when selecting components was the relatively high voltage of the tuner signal. I like old school amps but they just didn't make them (in my price range!) that accepted inputs of that level. Thank goodness for MTX :)

I'm definitely interested in what the other board has to say - I'm always open to learning more about circuit design...

d-

I never knew it was a 5 volt signal, is that 5 volts rms, at max unclipped volume?

Edit: I'm reading your write up. Just an FYI, you can actually buy the individual pins with wires attached that will clip right into your factory radio harness to add the rear channel speaker wires, and then run speaker wires to the back from there (this is if you wanted to leave the factory in-dash wiring intact up front and make your connections in the trunk).

And ah yes, el_duderino. Ken has more audio knowledge in these cars than anybody I've ever spoken with.

I never knew it was a 5 volt signal, is that 5 volts rms, at max unclipped volume?

Edit: I'm reading your write up. Just an FYI, you can actually buy the individual pins with wires attached that will clip right into your factory radio harness to add the rear channel speaker wires, and then run speaker wires to the back from there (this is if you wanted to leave the factory in-dash wiring intact up front and make your connections in the trunk).

Right - 5V RMS, max unclipped.

Didn't know you could buy the individual wires - that would have been good knowledge :) Glad I didn't spend much money on the complete harness!

All the important components are in my trunk, so I luckily I didn't have a lot of new wiring to run - the existing speaker wire is very good and more than adequate for anything short of competition level volumes...

d-