Harman Kardon Amp Upgrade Options

[vonmayr]

I preface this by saying that I enjoy high quality audio, and am an electrical engineer, but am NOT A CAR AUDIO EXPERT. If I have written anything in error or you want to amplify (pun intended) based on your experiences, please feel free to add on.

I have owned an F30 and currently own an F80. In both cars I have installed Bavsound Stage 1, and just got done installing the Ghost subs. In my opinion, the stock HK system is like a 5/10, with the stage 1 makes it a 7, Ghosts improve it but I need more time with it to tell how much. But I can't equalize to my satisfaction, or get my sound stage where I want it, and it leaves me wanting more umph, if nothing else. I like to listen at volumes near 75% of the volume maximum and I know I am hearing some clipping. That to me means AMP to give more headroom.

I have spent the last 3 days combing through this forum and other resources to see what is possible to do to upgrade the OEM HK amplifier in the F8x. I have come across lots of nuggets of information spread across hundreds of posts by really smart people like Technic, and I have done a bunch of independent reading.

In hopes of making it easier for others who are thinking about the same thing, I offer the following compendium of what I have learned here below, in one place.

I personally have not come to a decision on a path forward.....

Replacing the OEM Harman Kardon Amplifier in the F80/F30:

The E9x/F3x/F8x HK system generates audio and control signals in the Head Unit and/or CiC (iDrive controller); those audio signals /data are transmitted to the OEM HK amplifier in the trunk (mounted on the driver’s side trunk wall) using a MOST (Media Oriented System Transport) bus. MOST is an industry standard high speed serial synchronous ring network topology which uses fiber optic cable to transmit audio and data. The MOST standard provides the basic networking interface functions, atop which BMW has created the Application Programming Interface (API) with a proprietary encoding protocol for the data. The fiber optic cable offers several advantages, including light weight, less bulk, noise immunity, and high speeds without the need for a signal repeater (due to cable length) for automotive applications. The MOST consortium runs the standards group so it is a common underlying architecture with each manufacturer’s unique software layer on top.

The use of MOST and the proprietary communication protocol create some challenges in upgrading the OEM HK amplifier, which are detailed as follows.

The OEM HK amp is a node on the MOST network along with the head unit, the iDrive controller, the multimedia controller, the combox, and the instrument cluster. The OEM HK Amp inputs are useless to aftermarket equipment unless you have an optical receiver and a proprietary decoder. This also means that if you unplug the OEM HK amp then you are breaking the MOST ring, which will impact all the other functions on that bus.

The OEM HK Amp is a Class D Amp with some DSP functionality. The amp receives and decodes the up to 5.1 data from the MOST bus, performs Dolby Pro Logic II (replaces Logic 7 from earlier units) Digital Signal Processing on the 7.2 audio, converts it to analog and amplifies (600 W total) into 7 channels at 50 watts/4 oms for the mids/tweeters), and 2 channels at 125 watts (the subs, at 7.2 ohms impedance). It draws power from the battery through the luggage compartment fuse box; it has one fuse to power for the DSP functions and one fuse for the amplification functions. A replacement OEM HK amp retails for approximately $1,200.

Now that the preliminaries are out of the way, there are then two ways to upgrade the OEM HK amplifier. Note that both of these options carry significant expense and require custom installation. There are several companies that have been able to create “plug and play” installations that consume the storage space under the trunk floor to provide space for the amplifiers and DSP units. One poster below notes that this is like a gift from BMW to the audio community - room for hidden racks close to the battery! This is done by creating a tray or rack of components and the unique wiring to hook up this rack to the OEM cables so that installation can be reversed at some point later if desired.

1) The primary (and most expensive method) is to remove the OEM HK amp and replace it with three (or more) components: a mObridge DA converter, a DSP (optional) and sufficient aftermarket amplification to soothe the savage beast you desire to tame. There are two proprietary decoders for the Harman Kardon MOST inputs: the OEM HK amp we are trying to replace and a mObridge DA converter. The mObridge DA converter receives the encoded MOST input, decodes it and provides normal RCA outputs. This allows you to get the flat audio signal before the DSP and amp, which is ideal for aftermarket upgrades, because it avoids the coarse OEM 7 channel equalization scheme, the speed sensitive amplification and equalization, and the Dolby Pro Logic II encoding. The mObridge RCA outputs can then be routed to the aftermarket DSP/amplifiers. There are two downsides to this approach. The first is the cost of the multiple components required to replace the OEM HK amplifier. The second is the loss of all Dolby Pro Logic II decoding for DVD playback/synthesis for Audio tracks unless you add it back in with the DSP you choose. The major positives are the ability to reconfigure the 7 channels into alternative arrangements (2, 4, or more channels), split the power to different portions of the system, add a trunk sub/amp, and to have very fine (third octave) equalization control over the entire audio spectrum in the car, with the many features a DSP brings to bear. This can be set up as a plug and play installation that can be removed in lease cars.

2) The second way to upgrade the OEM HK amp requires you to “code” your BMW head unit output from HK to stereo or HiFi (which is the base system (HiFi in the US, stereo in other regions)). All BMW professional head units and iDrive units in the F3x/F8x may be coded to output on one of 3 different kinds of outputs: high level analog (Stereo), low level balanced analog (HiFi), and MOST (digital, Dolby Pro Logic II, Harman Kardon, individual audio). This opens the path to replacing the OEM HK amplifier – you code your BMW Head Unit/iDrive to output from the Stereo or HiFi outputs. RCA cabling must be run from the trunk where your DSP/Amplifiers will reside to the back of the head unit in the dash where they connect to the existing RCA outputs, and a MOST bus termination must be installed in place of the OEM amplifier. Aftermarket amps and DSP with analog (high or low level balanced) inputs then can be connected in place of the MOST OEM amp. The downside of this approach is loss of Dolby Pro Logic II, the risk of the dealer recoding the car when you have software update, and the extra cabling - installation of which requires removal of a significant number of trim pieces. You then have an option to use a plug and play amp/DSP combo. A popular one is offered by Bimmertech http://www.bimmer-tech.net/shop/bmw-...udio-retrofits for roughly $800. This method adds complexity because you need to figure out how to wire up the 9 channels from the HK system – there might be a custom harness available somewhere to do that but I haven’t found it.

There is little debate among audiophiles that the loss of Dolby Pro Logic II is not a problem - that you are better off with pure stereo even for movies. After you have chosen one of these two methods, the path forward is fairly common.

1) Choose a Digital Signal Processor (DSP) to allow you to balance the up to 8 channels, set crossover frequencies and filter shapes, time align the speakers, and equalize to taste for your unique setup using 30 or so channels to be very precise. There are a stunning number of DSP’s on the market, but the ones I have seen the most in setups are Mosconi and Helix. One of the mObridge units (the DA3) comes with some DSP capability - depending on your tastes that may eliminate the need for a stand alone DSP.

2) Choose your amplifiers – they need to be matched to your speakers – most folks recommend changing out the OEM speakers because you can get higher quality outputs. Some recommend just replacing the amp. Aftermarket amps from JL audio and Helix seem to be the leading choices.

Popular speakers include BavSound, but you could do a lot of others for the mids and tweets (Jehnert, Gladen, Focal, etc) that all make nice plug/play options. You will want to upgrade the underseat woofer as well. Lots of companies make drop in solutions now; the same ones that make the mids and tweets. Be aware that if you do the BSW Ghost subwoofer, its impedance is matched to the OEM HK amplifier at 8 ohms, and this makes them harder to drive with aftermarket amplifiers, which prefer 4 ohm impedance.

Thanks to aboulfad for the four attached PDF with more details about the amp, wiring harness pin outs and diagrams, and stock speaker specifications.

Hope this helps.

Edited 1/7/16 to reflect new data from attached PDF on the OEM HK amplifier.

[cays]

Great info!

[OneRib]

Nice post and explains why I will not be doing any more work on my car's audio system (already have Bavsound woofers and stage 1).

[Reach]

Well put. This will help a lot of people understand how to consider a full system upgrade. Sticky worthy even!

Once / If we get a Technic harness for this setup it will simplify the wiring of the aftermarket components.

[vonmayr]

Originally Posted by Reach

Well put. This will help a lot of people understand how to consider a full system upgrade. Sticky worthy even!

Once / If we get a Technic harness for this setup it will simplify the wiring of the aftermarket components.

Thanks. I appreciate the comment.

[vonmayr]

Originally Posted by OneRib

Nice post and explains why I will not be doing any more work on my car's audio system (already have Bavsound woofers and stage 1).

Not sure it's for me either. But I was interested enough to look for options.....

[OneRib]

Originally Posted by vonmayr

Not sure it's for me either. But I was interested enough to look for options.....

I agree and I'm glad you did. At least everyone who reads it will understand there will be no plug and play bimmertech amp coming anytime soon.

[sittingmongoose]

Why couldn't bimmertech make a package though? Either buy combining those three things, creating a package to do option 1 or just taking the hk one apart and improving it.

[nelson29]

Originally Posted by sittingmongoose

Why couldn't bimmertech make a package though? Either buy combining those three things, creating a package to do option 1 or just taking the hk one apart and improving it.

It's me again Nelson from Bimmer-Tech. Because it wouldn't be a plug and play solution and that's what most of you guys are looking for. I could create a package with everything that you need but 1. It won't be cheap and 2. Will require custom wiring.

[nelson29]

This thread deserve to be a sticky! GREAT JOB!!!

Also with the second option we could create a harness for it.

[DocWeatherington]

I hope BMW steps up the game in the future with a better audio system as an option. I wonder if that B&W system will ever launch in the current 3 series that is in the system.

[sittingmongoose]

Originally Posted by nelson29

It's me again Nelson from Bimmer-Tech. Because it wouldn't be a plug and play solution and that's what most of you guys are looking for. I could create a package with everything that you need but 1. It won't be cheap and 2. Will require custom wiring.

Could you create a wiring solution that would make it easier for us?

[Mandi90TT]

Originally Posted by nelson29

It's me again Nelson from Bimmer-Tech. Because it wouldn't be a plug and play solution and that's what most of you guys are looking for. I could create a package with everything that you need but 1. It won't be cheap and 2. Will require custom wiring.

This. Also, it would require some custom placing/building of where the amps will go. Probably not within the skill range for someone who was able to install the BavSound speaker, but that was the limit of their car audio skills.

Honestly, guys, the most bang for your buck route to get better audio from the HK system, is by doing the BavSound Stage 1 for the speakers, doing an underseat replacement of the mid-woofers (either Bavsound, Jehnert, or Gladen, all of which are relatively plug and play) and doing the MusiccarNW add-a-sub, which adds a 10" sub to the trunk and depending on the options you choose, uses the HK amp outs to send a signal to an amp which can power your sub, and if you choose this option, power the mid-woofers under the seat.

I'm no audiophile, but I have done personal custom installs on cars I have owned, including very high-end bi-amping mids and tweeters and fiddling with DSPs to create the perfect sound stage. By doing all the above (what I said in the long paragraph with the BavSound speakers and such), you get a very nice sounding system, and I don't think you are going to get anything better without spending lots of time and money, and definitely not a very good return on your dollar (in other words, very little bang for your buck) You can certainly spend another 5-10k on a setup that Nelson from Bimmertech linked to in another post, but again, unless you have very finely tuned ears, you won't notice a difference between what I did, and what that setup in the linked post has.

As an aside, thanks for the info regarding the second option in the original post, I didn't know you could code it to believe it is a hifi system vs an HK system. Makes sense, though. In fact, the original post has a lot of good info, thanks for putting it together.

Also, here's a link to my MusicCarNW Add-A-Sub install, contains some info that people might find useful.

[vonmayr]

Originally Posted by Dave 90TT

This. Also, it would require some custom placing/building of where the amps will go. Probably not within the skill range for someone who was able to install the BavSound speaker, but that was the limit of their car audio skills.

Honestly, guys, the most bang for your buck route to get better audio from the HK system, is by doing the BavSound Stage 1 for the speakers, doing an underseat replacement of the mid-woofers (either Bavsound, Jehnert, or Gladen, all of which are relatively plug and play) and doing the MusiccarNW add-a-sub, which adds a 10" sub to the trunk and depending on the options you choose, uses the HK amp outs to send a signal to an amp which can power your sub, and if you choose this option, power the mid-woofers under the seat.

I'm no audiophile, but I have done personal custom installs on cars I have owned, including very high-end bi-amping mids and tweeters and fiddling with DSPs to create the perfect sound stage. By doing all the above (what I said in the long paragraph with the BavSound speakers and such), you get a very nice sounding system, and I don't think you are going to get anything better without spending lots of time and money, and definitely not a very good return on your dollar (in other words, very little bang for your buck) You can certainly spend another 5-10k on a setup that Nelson from Bimmertech linked to in another post, but again, unless you have very finely tuned ears, you won't notice a difference between what I did, and what that setup in the linked post has.

As an aside, thanks for the info regarding the second option in the original post, I didn't know you could code it to believe it is a hifi system vs an HK system. Makes sense, though. In fact, the original post has a lot of good info, thanks for putting it together.

Also, here's a link to my MusicCarNW Add-A-Sub install, contains some info that people might find useful.

Dave - your post was one of great interest in my research. Thanks for the kind words - putting this together was fun. And your point about bang for the buck is exactly what I am weighing - given that I am at 80ish percent of damn good how much am I willing to spend in pursuit of that last 10-20 percent. Am I willing to give up trunk space to get it? Etc.

I had one question but since it was an old thread I didn't ask it - I was dying to ask. Now I will! Why didn't you/musicarnw pick off the underseat sub signal straight from the amp instead of wiring from the underseat subs back to the trunk and from the trunk back to the subs?

[Mandi90TT]

Originally Posted by vonmayr

I had one question but since it was an old thread I didn't ask it - I was dying to ask. Now I will! Why didn't you/musicarnw pick off the underseat sub signal straight from the amp instead of wiring from the underseat subs back to the trunk and from the trunk back to the subs?

No problem, any more questions, feel free to ask as well.

In answer, we didn't pick the underseat sub signal from the underseat subs. the signal was picked directly from the HK amp, sent to the LC2i, and then split by the LC2i, with the mid-bass going to channels 1 and 2 of the JL Amp (150x2 watts) and sent to the underseat subs. The sub-bass went to bridged channels 3/4 and 5/6 of the JL amp, and then sent to the trunk sub (600 watts)

Sorry if there was any confusion in my post.

[vonmayr]

Originally Posted by Dave 90TT

No problem, any more questions, feel free to ask as well.

In answer, we didn't pick the underseat sub signal from the underseat subs. the signal was picked directly from the HK amp, sent to the LC2i, and then split by the LC2i, with the mid-bass going to channels 1 and 2 of the JL Amp (150x2 watts) and sent to the underseat subs. The sub-bass went to bridged channels 3/4 and 5/6 of the JL amp, and then sent to the trunk sub (600 watts)

Sorry if there was any confusion in my post.

Confusion was on my part. I was thinking of a different thread.... so to be clear the kit wired the JL amp outputs back into the extant factory wiring for the underseat subs?

[Mandi90TT]

Correct. The factory wiring is able to handle the increased current flow. Certainly, if you went to something crazy (600 watts to each underseat mid-woofer), you would want new wiring....but no speaker you would be able to fit underseat would be able to handle that power anyhow.

[nelson29]

Originally Posted by sittingmongoose

Could you create a wiring solution that would make it easier for us?

Yes but are you willing to run new cable from the radio to the trunk? What are wanting to do exactly? Complete system overhaul? Just want more bass?

[nelson29]

Dave 90t- you don't have to spend 5-10k for a system. With about 3k you can do a nice system that will sound better than the B&O system.

[vonmayr]

Originally Posted by nelson29

Yes but are you willing to run new cable from the radio to the trunk? What are wanting to do exactly? Complete system overhaul? Just want more bass?

Nelson asks a really good question here - I don't think that there is a fits all solution. We all need to first decide what it is we want when we upgrade from here.

If you want more bass, then what Dave 90TT suggested is an approach that doesn't require you to replace the amp - you can supplement it. And it takes some of the load off the underseat subs

If you want more power to the cabin speakers, how do want to configure the system? Keep it at 7.2? Doesn't make much sense without the logic 7. What channels do you want to keep? How do you want to combine the channels that you do keep? What speakers do you have? If you have bavsound then their crossovers were designed for the stock system and may impose limitations on your future options.

If you are going to spend 3 , 4, 5, or 10K, you will want to answer these questions for yourself. With all these different combinations of choice, it seems unlikely that a single choice would work for everyone.

[nelson29]

The most cost effective solution is recoding to Hifi, running new wire from radio to trunk and using our amp. You will lose a pair of the rear speakers and center, trust me logic7 is overrated.

Equipment list-

3 way speaker set $800-$1000
Bimmertech amp/dsp $800
Labor and coding-Roughly $600 or DIY.

With this option you can easily add a trunk sub if you want more bass.

[Mandi90TT]

Originally Posted by nelson29

Yes but are you willing to run new cable from the radio to the trunk? What are wanting to do exactly? Complete system overhaul? Just want more bass?

While most people actually would be able to do that (it's pretty simple, really), most people think they don't have the skills to do so, and would not want to try.

You are right, the bimmertech amp and speaker would cost less than 3k, but I think people that are asking are looking to keep the entire soundstage (including the 7.2) and that will cost significantly more than 3k. That's looking at the moBridge DSP to get the signals, two amps to power the speakers and new speakers (even just the BavSound speaker option), and that doesn't even count the cost of anything to improve the bass. Because you know I'm all about that bass, about that bass, no treble...