B&O Sub upgrade with stock amp

[acarzt]

I search, and could only find one example of someone doing this and they abandoned it and added an amp...

So I figured I'd try it again myself, and i'm happy to report that, IT WORKS! And, it sounds better than the stock sub to my ears.


I decided to go with a Kicker Comp C 8" DVC because it has decent sensitivity and relatively low power requirements.

https://www.kicker.com/comp-c-8-dvc-subwoofer


I used the method in this thread to cut the stock box so the sub can be mounted:

https://www.bronco6g.com/forum/threads/b-o-sub-installed-on-base-bronco-…-sorta….37207/


I also added some felt to the opening of the box to raise and even out the mounting hole since it wasn't perfectly smooth. I had planned on adding polyfill, but I forgot and I'm not sure it actually needs it anyway.


I used info in this thread for the wiring, and part numbers. I would recommend ordering the clips ahead of time. I was being very careful and still managed to break one. Those round rubber and white ones are easy to break if you pull on them... get a plastic pry tool to pop those off.

https://www.bronco6g.com/forum/threads/b-o-sound-system-complete-upgrade-done-.41031/




I hadn't seen this mentioned anywhere either, but the wire colors inside the box are different from the wire colors in all of the wiring diagrams and the wires that connect on the outside of the box. I haven't seen adapters for this anywhere so I had to cut them off. The Black and Purple wires inside the box are negative, the Yellow and Green wires are Positive.


Was it worth it? Maybe... I just did the swap yesterday so my listening has been limited... So far though, the bass seems to be cleaning and punchier. If I turn bass all the way up in the tone setting, it's definitely louder than the stock sub. Don't expect mind blowing bass though, it IS still being run by the stock amp. I still have the option of adding an amp later though if I need more!

I also just swapped out the kick panel speakers (they're not adding any bass, I listened to them without the sub) and I'll be swapping all of the 4" speakers today. (all Alpine Type S)


Edit: Fixed links.

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[LSU Jonno]

I swapped out all of the B&O 4" speakers as well, and I think that's enough audio upgrade for me. But if I did go any further, I'd definitely start with just a sub upgrade before adding an amp, just like you did. I've been tempted, but I've got so many other upgrades to do that this is way down on my priority list.

Glad to know you think it makes a difference.

 

[ATLBronco75]

I had hoped to do this but all the advice said do the 5 4" speakers first. Thanks for posting about it. I'll probably do my Sub after the 4" speakers.

 

[Jhuff]

Edit 7-1-22: All of my issues below were user error, and I could definitely recommend the Polk DB. The factory sub is still technically a little louder/boomier , but I am sure I gained in quality.

Interesting. I just finished installing my new sub on the OEM amp myself. I chose the Polk DB 8" which has slightly higher RMS than yours, as well as one or two DB less sensitive. Had to modify the box a little to get the bigger Polk ring to seat, though.

I took a half-assed DB reading before and after with the same song at my normal volume (11) and the Polks are as loud, if not slightly louder, than stock.

It is a little punchier on some frequencies and a little slower/weak on others though. Looking forward to see what happens when they break in. I do think it actually sounds better despite some sluggishness on certain songs.


Edit: I've been running the sub for several hours with no real improvement. While (mostly) punchy at normal volume, there is no linear increase as I turn the volume up (the sub doesn't get as loud relative to rest of speakers).

 

[acarzt]

Weird about the sub not getting loud... I actually have to turn the bass down in the tone setting or it gets too loud... Maybe there is a wiring issue?

Too bad you're not local to Texas, I'd let you listen to mine.

 

[Jhuff]

Weird about the sub not getting loud... I actually have to turn the bass down in the tone setting or it gets too loud... Maybe there is a wiring issue?

Too bad you're not local to Texas, I'd let you listen to mine.

I've actually experienced significant improvement since that last post, so maybe this speaker material benefits from break-in more than others. Will give it more time. Bass is still pretty dead on one particular track (old Run DMC) compared to OEM. And this is with the settings heavily favoring bass.

The Polk DB, as advertised, shows slightly less sensitivity than yours, so that could be part of the issue. From my reading, sensitivity ratings between manufacturers may not be accurate, so we might be further off even yet.

I still plan on checking my install: both polarity and whether I removed enough box material to not leave gaps, or put the larger sub frame into a bind when I tightened it down.

I don't want to hijack your thread with my results, but this could end up being a useful place for speaker comparisons.

 

[acarzt]

Hijack away

I also did some sine wave sweeps with the stock sub and the Kicker sub. It seems like maybe there is a crossover right around 100hz. There is a very noticeable dip there for both subs. It could also be the stock sub box port tuning. I've thought about plugging the port to see if that changes the sound at all.

 

[Jhuff]

Hijack away

I also did some sine wave sweeps with the stock sub and the Kicker sub. It seems like maybe there is a crossover right around 100hz. There is a very noticeable dip there for both subs. It could also be the stock sub box port tuning. I've thought about plugging the port to see if that changes the sound at all.

Ugh. It was user error. I opened the sub back up to find plastic wadding everywhere... I had plugged all the voids and horns of the enclosure while filing off plastic and never removed it. Also pretty sure the plastic nub at 6’oclock of the opening was preventing any sealing. That nub is now gone.

The Polk DB sounds great, but I'm still pretty sure the factory sub was more sensitive and technically louder at peak volumes (or at least certain frequencies); But I am very happy with the quality of sound I'm getting, until I decide to add an amp, if I ever do

 

[MKZoom]

if few things to note:

#1 you arent going to see "break in" changing the sound beyond the first handful of seconds. in the case of a subwoofer, just napkin math shows that at 50Hz you will very quickly have reached hundreds and thousands of cycles of the components that move in the speaker.

#2 the factory sub is ported. depending on what speaker you place in the box the sound could be vastly different. sealing the end of the port will make the box effectively a sealed box which may or may not improve your output over the not sealed box. it basically acts on a balance of port length, diameter and volume inside the box reacting to the speaker. you can attempt to "tune" your box by adding polyfill to the box (success is not guaranteed). if you know the specifications of your speaker you could use some of the various online calculators to help steer you towards what if any steps you should take on any enclosure medification.

 

[acarzt]

if few things to note:

#1 you arent going to see "break in" changing the sound beyond the first handful of seconds. in the case of a subwoofer, just napkin math shows that at 50Hz you will very quickly have reached hundreds and thousands of cycles of the components that move in the speaker.

#2 the factory sub is ported. depending on what speaker you place in the box the sound could be vastly different. sealing the end of the port will make the box effectively a sealed box which may or may not improve your output over the not sealed box. it basically acts on a balance of port length, diameter and volume inside the box reacting to the speaker. you can attempt to "tune" your box by adding polyfill to the box (success is not guaranteed). if you know the specifications of your speaker you could use some of the various online calculators to help steer you towards what if any steps you should take on any enclosure medification.

That's not completely true about break in. The spider and rubber surrounds on some speakers can be really stiff when they're new and start to loosen up over time and the sound can change.

 

[MKZoom]

That's not completely true about break in. The spider and rubber surrounds on some speakers can be really stiff when they're new and start to loosen up over time and the sound can change.

correct, a spider fresh off of the assemble line will be stiffer than one that has been cycled some # of times (this is true of surrounds as well but they are generally much more complaint than the spider)

BUT, a well-designed speaker will have a stable compliance from a thousand cycles into the millions. MOST likely case is that the speaker has already "broken-in" before its ever left the factory.


happy moding!

 

[Jhuff]

correct, a spider fresh off of the assemble line will be stiffer than one that has been cycled some # of times (this is true of surrounds as well but they are generally much more complaint than the spider)

BUT, a well-designed speaker will have a stable compliance from a thousand cycles into the millions. MOST likely case is that the speaker has already "broken-in" before its ever left the factory.


happy moding!

I am in the camp that knows break-in is technically happening, but not knowing whether it will be noticable. Since I was trouble-shooting, I had to take the possiblity into account and give it some time before making my decision.

My decision: adding a 300w amp to my 300w Polk, deading the box and fenderwell, and covering the port with deadener as an experiment. After this, all of my complaints disappeared. I simply needed more watts and got lucky that the closed box worked for my setup. It sounds great!

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