Help adding a sub

[TexasKid]

I took my 135i (stock stereo) down to a high-end stereo shop to add a 10" sub & amp...they warn me that the stock stereo reduces bass as speed & volume go up. I didn't beleive them so I had them install a JL 10W3 and JL 250/1 mono amp that I had in a previous car (and sounded amazing). I pick up the car and they were right...it sounds like SH*T. How can this be fixed? Is there a certain location they should tie into the stock wiring to avoid this decrease in bass frequency? HELP!

[rawbert54]

there are several products my mobridge, phosgate, jl and others that will fix that. expect to spend about $300 new. the problem is you need something to send an unfiltered signal to your amp (i.e. the volume is not adjusted according to speed ect) this will allow the sub to play without the extra signal processing from the radio.

[TexasKid]

Mobridge?

[rawbert54]

mobridge makes a preamp that plugs into the most bus. it allows you to control the volume of the amp independent from the radio. if all your adding is a sub, this is a simple way to get the results most people want (more bass). no wires need to be cut or spliced. if you plan on doing an entire system upgrade, their preamp and an audio summation device (360 for example) will produce the cleanest and best results.

[tkbr0wn]

I thought you could turn the speed volume adjustment off in the menus?

[Citizen Z]

He doesn't need the MOST bridge shit. Only the Logic 7 equipment benefits from that and the OP has base American spec equipment which is an analog signal between the HU and the OEM amp. And the sub frequency does NOT change based on the vehicles speed. Volume can change but you can turn that off. (Read the manual). What I recommend is taking a pre-amplified signal from the head unit back by the amp and plugging it directly into the hi-gain JL amp input. Do a search over at e90post for the wiring diagram.

TexasKid: your 10" is going to sound like ass in your trunk because of how much sound deadening the rear seats provide. You'd need a 12" in a bandpass box with at least 500w to punch through with any decent amount of power and quality. This is why so many people are just upgrading the 8"ers under the seats and amplifying those. Even though they're small they're perfectly positioned so you get maximum benefit from the sound.

[rawbert54]

mobridge allows you to connect an amplifier through the most bus. logic 7 system or not, the car has a most bus (aka a pure digital signal from the radio). the difference is that the basic radio does not use the most bus to get the signal to the amp. that pre amplified signal your suggesting to use requires wire cutting or splicing. the da100o or da2000 from mobridge is like a PAC, but instead of using crappy sounding line level inputs like your suggesting, its a pure digital siganal. additionally, when removed from the car, you cant tell it was installed. it also does not limit you to amps with high level input.

even if you turn off speed sensitivity, the bass volume does not rise equally with the rest of the stereo when you turn it up. this effect is produced by the headunit and is not adjustable. using your method, your still sending a processed signal, with this effect, to the jl amp. Its just not as noticeable because your sending much more power to the speakers now, but it is still happening. In order to eliminate this effect, a summation device is necessary (such as clean sweep or 360)

My brother has the exact installation your suggesting, using a jl mono 500 powering 13w7. his bass should be awsome, but its not because of the effect i mentioned above.

your right sub frequency does not change, but volume does. also, i hate bandpass boxes. your limited to the port frequency of the box and if you have nice speakers, you loose the tonal quality in a bandpass. sealed and ported enclosures have a much wider frequency range. why do you think you seldom find bandpass enclosure in home audio systems.

[TexasKid]

I don't have the Logic 7...just the basic stereo.

[adrean8j]

Originally Posted by Citizen Z

He doesn't need the MOST bridge shit. Only the Logic 7 equipment benefits from that and the OP has base American spec equipment which is an analog signal between the HU and the OEM amp. And the sub frequency does NOT change based on the vehicles speed. Volume can change but you can turn that off. (Read the manual). What I recommend is taking a pre-amplified signal from the head unit back by the amp and plugging it directly into the hi-gain JL amp input. Do a search over at e90post for the wiring diagram.

TexasKid: your 10" is going to sound like ass in your trunk because of how much sound deadening the rear seats provide. You'd need a 12" in a bandpass box with at least 500w to punch through with any decent amount of power and quality. This is why so many people are just upgrading the 8"ers under the seats and amplifying those. Even though they're small they're perfectly positioned so you get maximum benefit from the sound.

I agree with CitizenZ on everything except about the 10" Subs. I had two 10" Hertz subs in the trunk of my 5er(E39) and they sounded great. I think it depends more on how the installing sets the speakers and amps up. Although you will need something with at least 500w like he says. My 10's were pushing close to 800w so it could work.

[rawbert54]

truthfully, an 8, in a sealed enclosure with 500 watts to it, facing away from the cabin in the trunk should drop pretty hard. you wouldn't have a lot of spl, but it would be loud.

the issue with the OP was that the bass volume would go lower as he turned up the rest of the system. If you read the OP setup its probably already connected the way citizen z said since most JL amps acept high level input. the mobridge wont fix the vomume problem, only make a cleaner and better sounding installation (because its all digital). in order to get around the OP's volume issue, he needs summation device. Every signal coming out of the HU is already processed, it needs to be deprocessed in order to get rid of this effect.

[Technic]

Originally Posted by rawbert54

mobridge allows you to connect an amplifier through the most bus. logic 7 system or not, the car has a most bus (aka a pure digital signal from the radio). the difference is that the basic radio does not use the most bus to get the signal to the amp. that pre amplified signal your suggesting to use requires wire cutting or splicing. the da100o or da2000 from mobridge is like a PAC, but instead of using crappy sounding line level inputs like your suggesting, its a pure digital siganal. additionally, when removed from the car, you cant tell it was installed. it also does not limit you to amps with high level input.

even if you turn off speed sensitivity, the bass volume does not rise equally with the rest of the stereo when you turn it up. this effect is produced by the headunit and is not adjustable. using your method, your still sending a processed signal, with this effect, to the jl amp. Its just not as noticeable because your sending much more power to the speakers now, but it is still happening. In order to eliminate this effect, a summation device is necessary (such as clean sweep or 360)

My brother has the exact installation your suggesting, using a jl mono 500 powering 13w7. his bass should be awsome, but its not because of the effect i mentioned above.

your right sub frequency does not change, but volume does. also, i hate bandpass boxes. your limited to the port frequency of the box and if you have nice speakers, you loose the tonal quality in a bandpass. sealed and ported enclosures have a much wider frequency range. why do you think you seldom find bandpass enclosure in home audio systems.

Please stop the non-sense.

Neither of the mObridge preamps are available yet so mentioning them is irrelevant in this thread.

The OP system is simply analog from the OEM HU to the OEM amp, so more irrelevant becomes mentioning those MOST preamps.

The OP wanted to add a sub, so regardless of having a Logic7 or a HiFi system the simplest thing to do here is to tap the underseat woofer high level outputs of the OEM amp.

Both the Logic7 and the HiFi has some speed-dependent sound adjustments, however it is only the Logic7 that has speed-dependent equalization and volume, the HiFi only has speed-dependent volume.

Therefore, there is no bass adjustment dependent of speed with the HiFi.

Now, it seems to me that the installer did not have enough experience in late model BMWs or something is not tuned right as this supposed decline in bass even if it existed as speed increases cannot be as radical as to make a sub installation to sound like SH*T, and I quote.

So I would recommend to the OP to take his car back to this installer and make them do the installation again, either by tapping the OEM amp woofer outputs or tapping the rear outputs of the OEM HU/rear inputs of the OEM amp. The JL Audio 250/1 is capable of either high or low inputs, and most important, balanced signals. So it is a very simple, direct interface with the OEM HU rear outputs as they are balanced.

A JL Audio wire to RCA cable is the perfect interface to accomplish this direct to amp connection: http://www.shopatron.com/product/par...r=91803/1451.0

Between the two possible connections, I would personally use that cable with the OEM HU rear outputs, set the 250/1 gains to 5V input (max input is 8V) low pass to 100Hz and enjoy some boom.

[rawbert54]

you are somewhat incorrect.
the entry level radio does turn down the bass volume as you turn up the system volume. this is true regardless of vehicle speed. This signal processing happens in the HU, so matter what amp you send that signal to (oem or jl) you will still have the same problem. BMW probably does this because most people dont want their car to "quad" for your average person, overwhelming bass does not sound good.

Im willing to bet whoever installed the OP's sub did tap the line level inputs. Its the most obvious (and ghetto) way of doing it. (unless they tapped the signal coming out of the oem amp. that would sound bad)

Line level inputs, balanced or not, will never sound as good as pure digital and your method requires you to cut or splice wires. Mobridge preamp avoids this. . Actually, their UK website says it available now (so maybe its more relevant than u think). Additionally, regardless of weather the OP has the entry level or premium audio, the car has a most bus (wow, i guess its becoming more relevent). admittedly, the most bus may need to be activated and mobridge products tend to be pricey.

"stop the nonsense" kinda rude dont you think, especially when your not 100% correct.

[Technic]

Originally Posted by rawbert54

you are somewhat incorrect.
the entry level radio does turn down the bass volume as you turn up the system volume. this is true regardless of vehicle speed. This signal processing happens in the HU, so matter what amp you send that signal to (oem or jl) you will still have the same problem. BMW probably does this because most people dont want their car to "quad" for your average person, overwhelming bass does not sound good.

Im willing to bet whoever installed the OP's sub did tap the line level inputs. Its the most obvious (and ghetto) way of doing it. (unless they tapped the signal coming out of the oem amp. that would sound bad)

Line level inputs, balanced or not, will never sound as good as pure digital and your method requires you to cut or splice wires. Mobridge preamp avoids this. . Actually, their UK website says it available now (so maybe its more relevant than u think). Additionally, regardless of weather the OP has the entry level or premium audio, the car has a most bus (wow, i guess its becoming more relevent). admittedly, the most bus may need to be activated and mobridge products tend to be pricey.

"stop the nonsense" kinda rude dont you think, especially when your not 100% correct.

Do you know the difference between a balanced signal and non-balanced?

Do you know the differences between HiFi and Top HiFi?

Do you even know the difference between tapping a wire and cutting it?

It is non-sense when you are the one that keep repeating incorrect information like it is correct. A lot of people read forums looking for solutions to their specific OEM audio issues, and your posts here do not provide any solutions. Just confusion.

No processing/signal manipulation is done in any BMW OEM HU/iDrive. All processing is done at the OEM amp. Depending of the OEM amp is the type of processing, if any.

The HiFi amp do not apply any processing to the signal according to BMW (pay some $30 here and look it up by yourself: www.BMWTIS.com), just a slight equalization that does not depend of any speed. Only the volume changes with the speed.

There is no need to even mention the mObridge digital preamps with the HiFi. They are irrelevant in this discussion in two ways: they are not applicable at all in the HiFi system and they are not available for sale in the USA yet.

The issue remains to be a suspect installation, most probably the wrong wires were tapped. It is as simple as that.

[Citizen Z]

Originally Posted by Technic

Do you know the difference between a balanced signal and non-balanced?

Do you know the differences between HiFi and Top HiFi?

Do you even know the difference between tapping a wire and cutting it?

It is non-sense when you are the one that keep repeating incorrect information like it is correct. A lot of people read forums looking for solutions to their specific OEM audio issues, and your posts here do not provide any solutions. Just confusion.

No processing/signal manipulation is done in any BMW OEM HU/iDrive. All processing is done at the OEM amp. Depending of the OEM amp is the type of processing, if any.

The HiFi amp do not apply any processing to the signal according to BMW (pay some $30 here and look it up by yourself: www.BMWTIS.com), just a slight equalization that does not depend of any speed. Only the volume changes with the speed.

There is no need to even mention the mObridge digital preamps with the HiFi. They are irrelevant in this discussion in two ways: they are not applicable at all in the HiFi system and they are not available for sale in the USA yet.

The issue remains to be a suspect installation, most probably the wrong wires were tapped. It is as simple as that.

+1; Rawbert; where in BMW literature does it say that there are speed sensitive EQ settings? (Do you know the difference between EQ and volume?) Show me or reference a page number in the manual. Also, you are aware that there are THREE different audio packages available world wide, only the MIDDLE and HIGH END versions of which are available in the US. Furthermore only the HIGH END version uses the MOST bus. The OP's installer probably fucked up the installation and you're getting your facts mixed up. Probably good facts for something somewhere, just not the OP's situation.

[rawbert54]

speed sensitive was actually first mentioned by the OP. The OP problem is that the radio (which does do its own equalization) turns down the bass as you turn up the volume. this has nothing to do with speed. you can be parked in your drive way and this will happen.

Yes, there are three available systems in the world. the middle and high end systems are available here in the us.

the bmws in the US have a most bus system. (all of them) even if you are using the entry level system in the united states, the car still has a most bus, its just not supplying the signal to the hifi amp that comes with the american entry level system.

if the car has the premium audio, you are correct, the top hifi amp uses the most bus to get the signal.

The most bus is how a CD changer and other options communicate with the radio. NO MATTER WHICH RADIO YOU HAVE IN THE US, THE CAR HAS A MOST BUS SYSTEM. if you can get your audio signal from there, it will provide the cleanest signal. additionally, a preamp connected to the most bus allows for independent volume control of that amp. this would allow the OP to adjust the bass to the level he wants.

Connecting to line level inputs is ghetto. Its a solution devised to overcome the limitations of connecting aftermarket equipment to the radio. its as simple as analog versus digital. there are no aftermarket radios that advertise analog preamp outs, because its an inferior connection.

The main problem with using the mobridge is its a little pricey and since its just now hitting the market, limited availablity.

The ultimate point here is, the analog signal supplying whatever amp used needs to be deequalized in order to have the bass rise equally with the volume of the rest of the system. Yes, you can connect an amp using the line level inputs but that signal is has been run through the EQ in the HU

[Citizen Z]

Originally Posted by rawbert54

speed sensitive was actually first mentioned by the OP. The OP problem is that the radio (which does do its own equalization) turns down the bass as you turn up the volume. this has nothing to do with speed. you can be parked in your drive way and this will happen.

I don't think that is accurate. I have the US base spec audio system and my Rockford Fosgate 3Sixty.2 equalizer indicates the output from the head unit is FLAT. Both my installer and my own tinkering have confirmed this. There is no eq coloring from the head unit beyond the user selectable options.

[rawbert54]

Equalization may not be the best term for whats happening in the HU. The radio simply turns down the bass volume as you turn it up. thats not exactly equalization, but i dont have a better word for it. The bass volume adjustment does happen when connecting an aftermarket amp to the HU using the analog signal. Ive seen it happen on more than 1 bimmer.


this conversation has gotten a little tense, and I dont mean it to be. No offense to anyone, and I trully do appreciate everyone's input.

[Technic]

Originally Posted by rawbert54

Equalization may not be the best term for whats happening in the HU. The radio simply turns down the bass volume as you turn it up. thats not exactly equalization, but i dont have a better word for it. The bass volume adjustment does happen when connecting an aftermarket amp to the HU using the analog signal. Ive seen it happen on more than 1 bimmer.


this conversation has gotten a little tense, and I dont mean it to be. No offense to anyone, and I trully do appreciate everyone's input.

It is not tense, it is that you keep giving incorrect information.

There is no EQ, no bass manipulation performed whatsoever in any OEM HU. None. That's the job of the OEM amp -if any.

The OP problem is not that bass is being decreased with speed or by volume, that was the OP installer's version of not knowing how this system works. The problem is one of installation. How I know? Because I'm tired of installing subs in late BMW's.

You ran with the installer's version in your posts, nobody else did.

If the OP tap any of the OEM HU outputs he will get a relatively flat, full range, unmolested, high voltage (5V) balanced signal that will be the perfect inputs to the 250/1. No need to buy anything other than the JL Audio cable that I post the link above.

No $300 magic box that is irrelevant and useless here, just a $12.95 cable.

The installer should have known about that cable if the 250/1 came from them.

[TexasKid]

Originally Posted by Technic

It is not tense, it is that you keep giving incorrect information.

There is no EQ, no bass manipulation performed whatsoever in any OEM HU. None. That's the job of the OEM amp -if any.

The OP problem is not that bass is being decreased with speed or by volume, that was the OP installer's version of not knowing how this system works. The problem is one of installation. How I know? Because I'm tired of installing subs in late BMW's.

You ran with the installer's version in your posts, nobody else did.

If the OP tap any of the OEM HU outputs he will get a relatively flat, full range, unmolested, high voltage (5V) balanced signal that will be the perfect inputs to the 250/1. No need to buy anything other than the JL Audio cable that I post the link above.

No $300 magic box that is irrelevant and useless here, just a $12.95 cable.

The installer should have known about that cable if the 250/1 came from them.

What the heck is an OP?

[Citizen Z]

Originally Posted by TexasKid

What the heck is an OP?

Its an abbreviation for Original Poster, i.e., YOU, the creator of this thread. Welcome to the internet, new here?

[TexasKid]

After a little frustration, I took the car back and had the head installer tune the amp...everything sounds great now, but man there is a ton of sound deadening in the trunk!

[TexasKid]

Originally Posted by Citizen Z

Its an abbreviation for Original Poster, i.e., YOU, the creator of this thread. Welcome to the internet, new here?

Not new...just have a life and don't spend 18 hours a day talking to people on forums, so please excuse me if I don't know all the terminology.