[Amggbb6]

Hey Guys, this is my first post. I have a 2011 335xi with the Harmon Kardon sound system. I am wanting to upgrade the under-seat subs to something like Rockford Fosgate. Will the factory amp be fine with this upgrade? Also, any other suggestions about this topic will be greatly appreciated.
Thanks,,

[ctuna]

Jehnert xe 200's or Helix/match speakers more fidelity or
bang for the buck.

The power is not all that good that 70 watt per channel rating
for the under seats is at 10 percent distortion.

http://www.e90post.com/forums/showthread.php?t=1144129

See entry 18 to download amp power chips outputs.
spec sheets indicate 10 percent distortion at 70 watts for the under seats.
And the underseats are more mid bass than a true subwoofer.

https://www.e90post.com/forums/attac...2&d=1435788287

See page 13

[Amggbb6]

Originally Posted by ctuna

Jehnert xe 200's or Helix/match speakers more fidelity or
bang for the buck.

The power is not all that good that 70 watt per channel rating
for the under seats is at 10 percent distortion.

http://www.e90post.com/forums/showthread.php?t=1144129

See entry 18 to download amp power chips outputs.
spec sheets indicate 10 percent distortion at 70 watts for the under seats.
And the underseats are more mid bass than a true subwoofer.

https://www.e90post.com/forums/attac...8;d=1435788287

See page 13

It is obvious that you know way more than I do but I thought I read somewhere that the amp puts out 125w to the subs. Is this not correct.

[ctuna]

Not on Logic 7 I don't know about the Individual audio system
because I have found no specs on that.
When I talk about power it's on a by channel basis.

When these car companys market stuff they tend to blow up the max
numbers without telling you the details. Like they cheated by using 2 ohm
speakers and the distortion is off the charts at rated power.

Specs on all three of the normally found systems are in the second link.
Also VpElectricity of MusicarNW who used to be on the forum is not a fan
of the Logic 7 system.

BMW stereo types
http://www.e90post.com/forums/showthread.php?t=352586
http://www.e90post.com/forums/attach...2&d=1266451970
http://www.e90post.com/forums/attach...2&d=1260829447
http://www.e90post.com/forums/showthread.php?t=343673
http://www.e90post.com/forums/showthread.php?t=138949
http://www.e90post.com/forums/attach...1&d=1209780605
http://www.e90post.com/forums/attach...1&d=1209780865
http://www.e90post.com/forums/showthread.php?t=641323
http://bmwcoders.com/forum/3-er-8/bm...1-e92-e93-291/
http://technicpnp.com/menuDiagrams/d...e90_92_93.html
http://www.musicarnw.com/page-2/
http://www.e90post.com/forums/attach...3&d=1169133185
http://www.e90post.com/forums/attach...4&d=1278871872

[D-e93]

I think with the stock amplifier, you will not get the most of of the subs you mentioned. I think the underseat subs might be a little underpowered right now. You need more powerful bass? Youd probably want to start with a good enough amp to carry you through. Im not sure whats recommended for the Harman Kardon system but for HiFi: https://www.audiotec-fischer.de/en/m...fiers/pp-86dsp . I would also recommend you look at not only "drop-in" replacements if you are handy with woodwork. Something like this is a great value and better sound: https://www.parts-express.com/morel-...-ohms--297-008

Also, if youd want to try. I do have a single Jehnert xe 200 I can sell you so you can do A/B comparison. https://www.e90post.com/forums/showthread.php?t=1502208

[mweisdorfer]

Originally Posted by Amggbb6

Hey Guys, this is my first post. I have a 2011 335xi with the Harmon Kardon sound system. I am wanting to upgrade the under-seat subs to something like Rockford Fosgate. Will the factory amp be fine with this upgrade? Also, any other suggestions about this topic will be greatly appreciated.
Thanks,,

I think your factory logic 7 amp will have a difficult time running the BMW Individual Audio under the seat subs. If you go that route, you will need a separate amp to run them. Something like a 4 channel that you can bridge or a 5 channel that gives you room to expand to a corner mounted sub in the trunk.

Personally, I modified the stock sub boxes and put in Kenwood Subs - Kenwood EXcelon KFC-XW800F.

They are not a direct fit. You will have to think outside the box in order to make them fit.

1) modify them stock sub boxes w/ dremmel (cut the fins out and cut a hole in the bottom so the sub can sit flush.
2) buy wood sub rings and use dremmel to sand them so they fit the stock sub box.
3) buy door insulation and place inside the sub box, around it and also block off the port to the side.


https://www.amazon.com/Noico-deadeni...697&sr=8-8

4) shim the seats up 1/2" with 1/2 SS nuts. You will need longer bolts for the rear. This isn't a big deal and you will not ever notice that the seats are 1/2" higher, unless you are really tall. I'm 6'1" tall, and I didn't feel a thing.

Once you get the truck mounted sub like a JL Audio 10" and open up the ski pass, the under the seat subs will sound amazing.

I have my entire system on an old school JBL MS - 8 sound processor. I set the high & low passes so the truck mounted sub plays all sound from 20 to 80 & the underneath seat subs play 80 to 200. Works perfect!

10W1v3 - 2ohm JL Audio 10" for the corner.

I paired mine with a Alpine MRV-V500.

Corner Mounted Enclosure -

https://rover.ebay.com/rover/0/0/0?m...2F152913063185

It will take about 3-4 weeks to get it, but at $200.00, you can't beat it. It's 100% Fiberglass, which is what you want. It's built to the exact specs of your sub. You just gotta tell them what sub you bought.

[kaigoss69]

You can amplify the L7 woofers with an external amp and get much better bass response. You will have to set a "subsonic" filter on the amp to cut (reduce) the very low frequencies, which could otherwise harm the speakers with the added power. What you will get is much better bass response, with very good mid-bass (like kick-drums) minus the sub-bass. So it depends on your music taste. If you like music with deep bass like rap or electronic, this is not for you, otherwise almost all music will sound much better and fuller. You would need a quality line output converter and a 2 channel amp. Both can be had for less than $250 and the install is relatively simple. Best to get a Technic add a sub harness so you don't have to cut any OEM wires, unless you are comfortable doing that. If this "first step" is not satisfactory, you can either replace the OEM woofers with something like the Ghosts, or better add an aftermarket sub to the trunk. In either case you ate not upgrading yourself into a corner, and can use the 1st step components in your later build(s).

[kaigoss69]

Oh, and in the L7 system, I highly recommend to add a tweeter to the center speaker. You can "borrow" the tweeter from the rear deck (if you have a sedan), and trust me you won't miss it back there. You will have better staging and imaging, and more "crisp" sound. I believe it is possible that the Logic 7 "tune" in our cars was made for a full-range center, and the tweeter was omitted for cost saving reasons. There definitely is a "hole" in the response without the tweeter there.

[GeorgeR]

Originally Posted by kaigoss69

Oh, and in the L7 system, I highly recommend to add a tweeter to the center speaker. You can "borrow" the tweeter from the rear deck (if you have a sedan), and trust me you won't miss it back there. You will have better staging and imaging, and more "crisp" sound. I believe it is possible that the Logic 7 "tune" in our cars was made for a full-range center, and the tweeter was omitted for cost saving reasons. There definitely is a "hole" in the response without the tweeter there.

My center speaker has been disconnected and the stereo imaging and sound stage is greatly improved. A good percentage make the same decision when upgrading the sound system.