Bobby Kinstle

Hmm that's a tough question as most of the speakers are pretty terrible. Let me describe what you'll get from each upgrade and you can decide which is the most important to you:

1. Front door midrange. The factory one is thin and harsh. Replacing this speaker will get you very clear vocals and bring in a ton of little details that you are totally missing like natural reverb from music played in a large room or all the tiny harmonics that makes a violin sound different from a trumpet.
2. Front door woofer. The factory woofer plays 70-260 hz, even though it gets signals below 50Hz. The factory horn structure causes a really annoying echo around 160 Hz, and it's utter garbage below 100hz. Replacing this speaker will dramatically improve bass overall, and you'll really pick up things like bass guitar, cello, and tuba. This is by far the most difficult speaker to replace in the entire car. I suggest buying the round 6.5" woofer from an A4 non B&O on ebay and then cutting it up to fabricate a mounting bracket for your new speaker. I cut up the B&O horn on mine and it was a huge amount of work. Maybe Metra will make an adapter some day.
3. Subwoofer: The factory sub is sloppy and muddy with very poor bass recovery (the cone continues moving too long after the signal stops). Replacing the factory sub will get you tight clean bass and will play a bit deeper. Be warned that you are almost certainly going to want to add a sub amp to get a boost in volume, and also a low pass filter set to whatever the front door woofer cuts out at (70hz for stock, lower is you replace them)
4. Rear door woofer: This one surprised me. The rear seat experience is really terrible and replacing this speaker made a night and day overall experience for the rear passengers. I personally like the improvement in rear fill so I set the listening position to ALL after replacing this speaker (fader set to slightly forward of middle). I've had nothing but compliments from my back seat passengers now. This is probably the easiest speaker to replace because you can use a metra bracket. The drivers I used cost only $6 each and they are no joke. I've used them in several projects now and they've always been awesome.

My next goal is to look into the center channel speaker which you can't turn off except for disconnecting it, and the front pillar tweeters to see if I can get them to play above 10K

Bobby Kinstle

I added a page to the spreadsheet called "My Car" that shows the work I've done to my own car so far.

Bobby Kinstle

I did some measuring today with the problem of overlapping bass between the new front door woofers and the subwoofer. The door woofers now play clean down to 45Hz, Roll off at 44Hz and are almost gone at 43Hz. SO this leaves me with a couple choices.

1. Install a 14 mH inductor on each coil of the woofer to block frequencies above 45Hz. SOunds easy but the only parts I can find are 4.5" long x 1.5" diameter, weigh 1.5 pounds, and cost $37 each
2. Set the crossover point to 53Hz which drops the inductor price to $11 each but then requires an exotic (expensive) capacitor on the front door woofers
3. Set the crossover point to 60Hz which means I can use a commonly available capacitor on the front door woofer.

Do you think 60Hz is too high to transfer from the door woofers to the sub? I'm afraid this will make the bass too strong if I really crank it up.

Alternatively I could buy an amp with a built in low pass filter but that's the most expensive and convoluted of all.

TT-S4

Have you only changed the speakers in you system?

The OEM system is, probably, actively crossed over.
So the audio output signal is split prior to being sent to the amplifier that provides power to it's set of drivers/speakers.

Simply adding a choke/coil to restrict the higher frequencies may or may not be the best route, as the OEM system is already controlling, crossing, the frequencies to each driver.

For the door bass drivers you stated that they play clean down to 45Hz.
What is the db/volume level at 45Hz compared to average db of the spectrum it's producing?

What are you hearing that you do not like, and want to change?


And, if you've tested the subs output, what frequencies is it reproducing?

What is your test tone source?

Bobby Kinstle

yes so far

Yes the factory crossover points are highly apparent and very too sharp to be passive filtering. Plus I've had the system all apart and found no crossover components except capacitors on the tweeters. Despite this capability, the factory set crossover points are totally inappropriate for the speakers they selected. Due to subwoofer physics, I think the only real solution is to add an amp with a built in low pass filter that can be set to 45hz.

I will need to remeasure

bass between 48hz and 70hz is too strong because the subwoofer is overlapping with the front door speakers. The factory front door speakers would not play below 63hz, and dropped off hard below 70hz. The factory amp sends to 44hz on this location so the higher quality speakers i used are now playing those notes.

I have not remeasured the drivers since installing the new ones. I have sent test tones to find the crossover points and frequency ranges but those are ear tests

Dayton Omnimic speaker testing software.

TT-S4

Per your comments, the door bass speakers are too loud. I'm sure you know the obvious, which is to turn the "bass" control down. I'm sure you've tried that.
And the problem with that is that, generally, "bass" and "treble" circuits at set at a specific frequency, so when you turn them up or down you're mainly affecting the level output of that frequency, and the circuit also has a slope such that it affects the frequencies near to that point, higher and lower. Typically, "bass" controls are around 100Hz, and "treble" is typically 10KHz. It's very limited to be sure.

Also, modern car audio systems have an automatic "loudness" control, which helps increase lower frequencies at lower volumes. The reason for this is because, at lower volume levels bass frequencies are perceived to be quieter relative to the higher frequencies. 'Loudness" is an EQ circuit that turns up the bass frequencies to help level out perceived volume/loudness at lower volume settings.

From my reading about this B&O system there is also a microphone in the cabin that is used to sense ambient noise and sound levels in the cabin, that are not coming from the audio system.
With this mic/s the system can auto EQ the audio system's output to compensate for those sounds that may be negatively affecting the system's output. It's pretty cool tech, but I'm not a fan of how it works in reality.
Some people aren't aware nor affected by those subtle changes, and that makes it good for the majority. But, some can detect it, and some like it and some don't. I'm not a fan of auto EQ adjustments to compensate for the car's cabin environment, as it affects various frequencies at different levels. To my ears it's like someone is playing with an EQ while I'm trying to enjoy the music. So, that's yet another factor in this OEM audio system.

Given that you do not like the high level of bass coming from your new door bass speakers, I would suggest you try a "high pass" filter and hear if you like the change.
A "high pass" filter is as simple as a capacitor connected inline with the positive/+ side of the speaker.

You also said that you see capacitors on the tweeters. Those are "high pass" filters, they are also called "bass blockers". Having capacitors on the OEM tweets indicates a cheap/inexpensive OEM solution. It also tells us that the high frequencies are not actively crossed over.
There are tests that can be done to read the signal going to the tweets, but it requires special equipment. And easy to do test would be to attach a "full range" speaker to the tweeter wires and play a full spectrum tone nothing how low the produced frequencies are.

Back to the door bass speakers. Capacitors are inexpensive and you can try a couple to see how your overall sound is affected and if you like it. For a high-pass filter to pass 80Hz and above, on a 4ohm speaker, you can use a 500uF capacitor.
High-pass at 100Hz would take a 400uF capacitor. Going with 100Hz and will help the new bass drivers to not have to struggle with reproducing such low frequencies under 100Hz. Not having to reproduce those very low frequencies will clear up the bass tones, along with helping bass and mid-bass imaging.

Given the information you give on the sub's audio reproduction, it seems that the OEM system is doing ok with passing sub frequencies only to the sub without the need for a low-pass inductor to strip higher frequencies out.

Sending higher frequencies to a sub causes it to work harder to reproduce frequencies it can't properly nor efficiently produce, and that can create a distorted bass sound, and I'm positive B&O are aware of that.
Running a test tone to the sub, while the other speakers are shut off/disconnected will give you a better readout as to what your sub is capable of doing, along with hearing how high of a frequency is being sent to the sub.
Knowing that will give a good indication what the xover point is.

Some other things to consider. Every speaker has it's "efficiency" rating. This is show in db, such as, 90db. What that means is that 1 watt of power driving the speaker, and testing it's "sound pressure level/SPL", it will produce 90db/decibles of volume measured at 1 meter away from the speaker. It's highly possible that the OEM speakers were not a very high efficiency, and your new speakers are a good bit higher.
For example; if the OEM bass speakers had an 88db efficiency and your new bass speakers are 91db, that is a +3db gain just by using higher efficiency speakers. A +3db gain in perceived volume is considered a doubling of acoustic energy.
IOW, that's a significant increase. That increase would be just like doubling the power to the original 88db speakers. So, adding speakers that are +3db more efficient is like having an amplifier with double the original power, say from 20 watts to 40 watts.
There is, of course, more to that, but in general a +3db higher efficiency speaker will be perceived as very much louder.
What you are hearing with your new bass drivers may also be that they are that much higher in efficiency.

I've already written too much. My suggestion is to try the high-pass, or bass-blocker, on those new door bass speakers and hear if you like the difference.

Bobby Kinstle

As I've mentioned above, it's not that the front door bass driver is too loud. It's that the frequencies that are played by BOTH the subwoofer and the front door woofer are too loud. (And lets be blunt, this isn't a *huge* problem) The factory system has the subwoofer output limited at about 75 Hz so that the subwoofer can cover the incredibly terrible bass performance of the front door woofer, which really isn't usable much below 70Hz (even though the factory amp continues to drive this speaker down to 45 Hz which is has no chance to play). So the options are:

1. Low pass the subwoofer at 45Hz
2. High pass the door woofer at 75Hz
3. Both 1 and 2 somewhere in between.

Option 1 is by far my most preferred route since the door woofers are musically detailed and the subwoofer is a sledgehammer.

And the problem with that is that, generally, "bass" and "treble" circuits at set at a specific frequency, so when you turn them up or down you're mainly affecting the level output of that frequency, and the circuit also has a slope such that it affects the frequencies near to that point, higher and lower. Typically, "bass" controls are around 100Hz, and "treble" is typically 10KHz. It's very limited to be sure.

The more I read about the B&O system, the more I think they don't do much at all. Its hard to tell except that I keep getting different stories all over the place. Most of the articles are actually about the A7 or A8 B&O systems, and people are just assuming that those things apply to the 4/5 series. The things they do, don't make sense like not driving the A pillar tweeters above 10KHz and driving the front door woofer far below it's capability. There does appear to be a loudness correction that's speed sensitive. If there was actually a microphone correcting things, I wouldn't have this problem in the first place, and the factory system would sound a lot better.

Using a first order butterworth filter as you describe would cause a 90 degree phase shift in the door woofer which I would rather not deal with. It may cause additional problems where they overlap the rear door woofers.

I'm very much aware why those are there, however, 4 of the 7 tweeters only play up to 10KHz which says there is also some active crossover happening here since they are all the same driver.

As it says in the spreadsheet at the beginning of this thread, the front door woofer is an 8 ohm, 100W driver. This means the capacitor inline would need to have a very low ESR, be able to pass up to 3.5A and a rating above 30V. We're basically talking motor start capacitors that cost $45-$120 each, and are huge. Also 100Hz is way too high since the sub only goes to 75ish, I would have a hole in the bass. I'm not worried about my 7" door woofers "struggling" even down to 45Hz, but it's clearly inappropriate to cut them off above the upper limit of the subwoofer. Fs on my woofer is 32Hz so at least the impedance is stable

Have you looked at the spreadsheet?
https://docs.google.com/spreadsheets...it?usp=sharing

Actually once I fix the overlap, the front bass and the subwoofer will both need to be turned up to match the midrange I used. It's only off a little bit and I'm sure the tone controls will get there since the bass control doesn't get into the midrange. If it's still a problem, maybe I'll add an LPad to the midrange to knock it down but probably not since I'll have to deal with the heat. As it is, both drivers have the same SPL rating but the speaker grill on the woofer greatly restricts it's output, even after I opened up all the blocked holes over the new woofer.

TT-S4

Ok great.
It sounds like you know what you're doing and what you need to get there.

To answer one of your questions above, I would not put anything below 100Hz or 80Hz into a door bass driver when there is a sub in the system.
And for small 6.5" bass speaker, I would even try 120Hz to hear if it produces a cleaner/clearer bass.
By removing the low bass/sub bass frequency from the door speakers that allows them to produce cleaner bass.
Subwoofers can easily handle 100Hz and below nicely. And given that the OEM sub is an 8", it can handle 120Hz and below, within reason.

If the door bass drivers are playing 80Hz cleanly, then set the xover for the sub to 90Hz, if it's 90Hz for the door, then 100Hz for the sub, etc. A slight 10Hz overlap is better to cover any potential "holes" in the spectrum.

Have fun with your project.

Bobby Kinstle

The front door woofer only plays to 260 Hz so I'm not worried about muddying up the mids. The midrange speaker I used is truly extraordinary which is great because it's a pretty short list of what can fit in there. Cello and trombone are soul melting on those drivers.

TT-S4

[QUOTE=Bobby Kinstle;25332557]The front door woofer only plays to 260 Hz so I'm not worried about muddying up the mids. The midrange speaker I used is truly extraordinary which is great because it's a pretty short list of what can fit in there. Cello and trombone are soul melting on those drivers.[/QUOTE


Sounds like you've got it all covered.