Bose Tweak Plus

Bose Tweak Plus VMax Vishay There has been a ton of Bose bashing on this forum and rightfully so. Before doing the "stuffing the sub mod" I had a hard time believing how poorly my Bose system sounded. I do not consider myself a current day car audiophile. I do consider myself a current 2-channel music lover with a home system that shamefully costs almost as much as some of our cars here. In my youth, I've owned car audio systems that included the original Fosgate amps, ADS Powerplates, Audiomobile with head units by Nakamichi. I haven’t done or had any custom car audio installations in the past decade but my other vehicle in the family is a Lexus with the Mark Levinson option. The reason why I state this is to kind of validate my somewhat aging "Golden Ears". First off, I have a 06 Cayman with Bose and PCM 2.1. I also added the DensionGateway 500 using a 160GB iPod classic with music ripped to AIFF files. I'm notsure if systems with PCM vs. CDR24 actually sound any different but my comments are based on my PCM based system. For the past year, I’ve enjoyed my Bose system after stuffing the sub with poly-fill. As many have noted, stuffing the sub really cleaned up the bass and allowed the mid-range and highs to come through the sound spectrum with less distortion. Although this modification made a remarkable improvement, I’ve always felt the bass was artificially bottomed out. I even disconnect the subjust to see how much sound was coming from the foot-well sub. As I suspected, the amount of low end extension was minimal. I recently got to a point where I wanted a bit more out of this system. I felt that the system obviously lacked some bottom end, warmth and detail. I read the threads here where some have added subwoofer enclosures in the rear hatch area as well as those who added an ultra-compact sub behind or under a seat all with reasonable success. I just wasn’t keen on altering my stock Cayman in appearance in any way. Eventually Iread in this forum where someone added Dynamat to the sub enclosure. They claimed an improvement of an additional 15% in sound quality when done in conjunction with stuffing the sub. I had some VMax reminisce lying around which is similar to Dynamat from a home audio project. I used these left over pieces of the VMax and adhered them tothe plastic sub enclosure as shown in the attached picture. You can purchase VMax here . You will only need one pack. Cost is $32.50. I also ended up removing approximately 50% of the poly-fill from the port thatI had stuffed earlier. I found that by leaving the cavity behind the 5x7 driver open and just fill the port gave my ears the most enjoyment. I now hear a deeper bass and a more cohesive musical presentation. I had originally stuffed the port with as much poly fill as possible. To remove the poly-fill I foundthat by using a stout wire or coat hanger and bending the end to a hook did the trick for easy removal of the fill. While pulling out the poly, grab some of it with the hook and twist the wire/coat hanger and the poly will gather and come out in large pieces. Here is what I have discovered once the sub wasback in place. First off all tone controls are now positioned at flat with no boost or reduction in bass or treble for the best sound quality. The music now has a warmth and fullness that was missing with the sub fully stuffed. Balance and fader controls are now positioned in middle with no left right front rear adjustment. Here is the most startling discovery. The system to me sounds best with the “Surround CDC” control engaged. This was never the case prior to doing either modification. It is impossible to have a realistic sound stage in an automobile because one cannot sit equidistantly between the left and rightspeakers. What the CDC processing does is make the speakers disappear. You can no longer sense where the sound is coming from but one has a sense that themusic floats in front of you. I would describe this as if it’s almost like you are wearing a set of headphones while driving. The next step is to enhance the upper register. You will be adding a bypass capacitor to the stock 4.7uf cap. Here is an article that explains how bypass caps work. A bypass capacitor valued at 0.01uf will not change the crossover point and will not cause any damage to your tweeters. This bypass capacitor is a Vishay Roderstein MKP-1837 Metalized Polypropylene film Capacitor in a value of 0.01uf. Total cost is 0.99 cents each. You will need two. You can get them here . Other bypass caps will work but the issue is going to be getting them in your dash. There relative zero room in there. The good thing is these Vishay are very small and are an incredible value where many hobbyists use them in their crossovers for there home audio speakers. The removal of the Bose dash mounted tweeters arerelatively simple. The middle dash mounted driver is not a dome tweeter but a mid-range or cone tweeter. It is different than the domes in the left and right side. The domes can be removed from the car as they are attached with mini Molex connectors. You will be adding the bypass cap to just the left and right tweeters. The tweeter grills just pop off. I used a single edge razor blade to gently wedge the covers off. If you have anything other than a black interior, you may want to use painters tape to protect the area that you are working on. Once you have the grills off, you can see the small domes. If you look closely, there isa ctually a small protrusion that faces or points inside the cabin of thevehicle on the dome that you will use to pull the tweeters out. The first time you pull these suckers out, itis a little tough. To integrate these Vishay caps into your system,a ll you need to do is solder them in parallel to the stock 4.7uf that is attached to the domes. I tried to solder the Vishay’s directly into the domes because they actually give you a fairly lengthy piece of wire coming out of the cap as seen in one of the attached photos. My three initial attempts were futile as I could not get the tweeters to sit properly back into the mounting brackets in the dash. When the domes are sitting in their brackets, there is zero clearance from the top of the domes tothe tweeter grill. I ended up extending (2) three inch wires from theVishay and then soldered them to the stock cap. I then fished the Vishay into the tweeter cavity and was able to pushthe domes into their housing and got the grills to slap back into place. Make sure to cover an exposed wire or solder with electrical tape. How does this system now sound compared to other aftermarket and the Levinson system in the Lexus? The Cayman system does not have the capability to produce sound pressure levels of a truly high end aftermarket system. It does not produce subterranean bass that passengers inadjacent cars can hear. It does however put out enough volume where I never run out of gain even with the windows rolled down while driving on the freeway. The bass believe it or not, on good recording actually makes it so that my chest feels the deepest bass notes. The bass feels natural and not exaggerated. The music has excellent tone and is not shrill or harsh in any way. The bypass caps give you that last bit of extension which was needed in my option as the musical presention now sounds rich and detailed. Because the Cayman has a very small cabin I believe Porsche and Bose decided that instead of trying to create a sound stage like one can do in a larger vehicle or at home, they did tried to make the best out of what they had. They did a great job engineering a sounding system in an environment with many compromises. It’s too bad someone at the very end of the process cut some corners and added a subwoofer with obviously incorrect specifications. The good news is with a bit ingenuity and time; one can really transform a decent sounding system into something that really is impressive to most. I hope some of you try these simple modifications as it will cost you relatively nothing and is reversible. Go get more out ofyour Bose systems. Enjoy.

Wow! Great write up, thank you!

Thanks, very helpful. The Bose system is not bad. I think the tuner portion of the cdr24 is horrible.

I did the stuff job, but the system still needed a bottom end "enhancement", so I bought a small powered sub from Crutchfield that more than fixed that issue. I'm going to try the tweeter mod and see what happens. Who knows, I may end up with a decent sounding system yet!

The caps went in this morning, and as advertised, the system sounds noticeably better. It will take the caps a few hours of playing time to calm down, but the Bose system sounds.....dare I say it....pretty decent. For less than 2 bucks in parts, not a bad deal at all!

The caps proved to be not powerful enough and my tweets and mids stopped working. New, more powerful caps installed. Bingo! My bargain attempt at fidelity enhancement has proved to very satisfactory. The $200 Sound Ordinance (Crutchfield house brand) powered sub is awesome.

Reid, That sounds odd. Something was not done correctly. Did you have the installers solder the bypass in parallel in conjunction with the stock caps? It sound like they eliminated the stock caps and only used the Vishay's which would change the crossover point drastically. Sorry the outcome was not as anticipated. Hoshi

Hoshi, Thank you for sharing the Bose Sub modifications. Question: I did order the Vmax backing material and wanted to know if I should try to cover as much of the Sub enclosure as I could or just stick with the placments that you had performed. I'm sure that you strategically placed them for a reason? I am not capping the speakers as you had illustrated that is above my knowledge base, lol. Your comments appreciated.

Hoshi, I suspect that you're right. I was very specific as to how I wanted the caps installed, but based on the results of the surgery, it seems the directions werent followed.

Lowrider, I'd use as much as of the VMax as possible. I only used strips because that's all I had available. If you are brave, you may want to remove the carpet and adhere the VMAX on the enclosure where the carpet is adhered to. You would then need to get the carpet to adhere to the Vmax. Also, make sure not to place the VMax on the channel guides that hold the sub in place. Don't be afraid to play around with the amount of stuffing in the port. I added and subtracted baseball sizes of waded poly until I got the bass to sound right. It will be a bit of a pain because you have to reinstall the sub each time you adjust the fill, but it really is very simple to do. Make sure to use the same portion of the same songs to evaluate. Good Luck and let us know your outcome. Hoshi

Reid, That is really ashame. What caps to you end up putting in? Do they have the stock values? Hoshi

Hoshi: I"ll let you know the outcome! Awaiting to receive the Vmax. Thanks

Hoshi, I dont know the value, but the wattage was much higher that the ones you suggested. In any event, the outcome was somewhat satisfactory in that the high end has been improved.

Hoshi, As promised, I wanted to report back to you on the results of covering the entire back of the Bose Sub with the Vmax sound deadening material. See below pictures. although it looks like patch work in placing (covering) the plastic side of the Sub it did work out very well. The Vmax was easy to work with since you could cut it and peel back the adhesive back and it would stick to the plastic. It took a couple of hours to do, since I used paper to make a pattern then traced it onto the Vmax so I could cut it. Interestingly, I started to thump my index finger on the plastic surface of the Sub before I covered with Vmax and then after covering it. I noticed the surface that was covered did not have that plastic sounding echo. Once I covered the entire plastic surface of the Sub I started thumping in different areas of the Sub, which produced either a higher or lower sound tone. I did not attempt to cover the carpeted side of the Sub, since it would have meant removing the carpet. It is really stuck on there. I then proceeded to insert the pillow stuffing. The day before I spent removing all of the pillow stuffing, which amounted to a plastic bag full. I stuffed in about 20-25% of the pillow stuffing into the port filling only the port (tunnel). I proceeded to install the Sub and listen to some music. I did take your advice and listened to a CD before and after the Vmax installation. The sound has some depth to it and I kept the bass at zero. It has a richer sound using the Vmax sound deadening material. I had my son listen to it and he preferred dialing the bass to + 4. IMHO adding the Vmax was worthwhile better than filling the entire Sub base cavity with pillow stuffing, which I was satisfied with before. Again, thank you very much for sharing your knowledge with us. I too did not want to move away from the stock looking interior with some aftermarket Sub Base in the trunk. The total cost of this Mod was $ 32.00.

Hoshi: Thanks for the truly excellent article. Given the trouble you had getting the tweeters back in the cavities, I was wondering if you had a photograph that captured the precise manner in which you soldered the three-inch wire extensions from the Vishay capacitors to the stock capacitors? This might help in getting it correct in one try. On my 2006 Boxster S , I found two other modifications to the Bose system also improved the sound. One was to add a damping mat—I used RAAMmat—to both sides of the aluminum covers on top of and in front of the engine. Then, on the side of the cover facing the engine, I used a layer of an acoustical foam, namely, Dynaliner, on top of the RAAMmat. This really help cut back on the transmission whine and associated racket from the engine bay. It also makes the intake and exhaust more prominent, which I especially like. I might also try pulling apart the Bose subwoofer assembly located behind the seats and layering in some RAAMmat.

MSP: Sorry for the delay in getting back to you. I do not have actual photos of my extensionwires but it requires very basic soldering. Any small gauge wire will work. The tweeters/caps should be removed from the car by undoing the Molexconnector which makes things super simple. As you can see in the attached photo (click to enlarge), the stock caps are adhered to the tweetersand should remain there. The drawn inRED lines represent the extension wire. Asillustrated, the bypass Vishay caps need to be soldered in parallel with thestock 4.7uf cap. Initially I had soldered the .01uf Vishay directly onto thestock 4.7uf cap and tweeter. The problemI had was physical space as I could not get the tweeter to snap intoplace. I believe it was issue withdepth. I simply added a couple inches ofwire small gauge wire to extend the wires extruding from the .01uf Vishay. This enabled me to tuck the Vishay’s into thespace occupied by the tweeter before snapping them back into place. Make sure you insolate the exposed wires onthe bypass cap and raw connections with electrical tape before installingthem.

Hey Lowrider, I’m glad you got some nice results with the VMax. I’m actually thought about removing my doorpanels and adhering some of the VMax to the subs in the doors. May this summer when it gets warmer. Now that you’ve got the expensive stuff done, you have toget your highs taken care of. Go toRadio Shack, buy a soldering pencil ($15), some solder ($6) and the bypass caps($2). You can always practice on somespare wire. You can go to “You Tube” andthere are tons of video on basic soldering. Once you get the tweeters out, it will take you less than five minutesto solder the extension wire to the caps and to solder the bypass to thetweeters. I just loaded a picture thatillustrates soldering points. Just do it.. Hoshi

Thanks Hoshi for getting back to me. I ordered two 0.01uf Vishay capacitors. I will report back with my findings after I have installed them.

Thanks for the write up and tip. Took me about 10 minutes to solder in the bypass caps and all seems good to go. Once I put the speakers back in the dash, the sound seems to reach a bit higher. I also found that removing about half the poly fill on the sub yielded a better fuller sound. Guess you just need to play arou d with works for your ear.

Bill, I'm glad got the mod done so efficiently. The caps will take 20 hours or so of playing time before they settle down and smooth out. I'm confident that you will enjoy them. Yes, one does have to play around with the amount of poly fill stuff until you get the right mix in the bass. It took me three tries until I got it right. Hoshi

As promised, I am reporting back after installing the 0.01uf Vishay capacitors to the tweeters in my 2006 Boxster S with the CDR-24 and Bose sound system . The project took me about two hours in total. I soldered the capacitors in parallel with the stock 4.7uf capacitors in the tweeters (as indicated by Hoshi in post #16). It was not easy to get the tweeters out. I used a small pair of needle-nosed pliers to pull back the clips on the sides of the tweeters and at the same time used a nylon interior tool to pry the tweeter up from the cavity it sits in. What's more, one Molex connector did not want to come away from the tweeter without some coaxing. The 0.01 capacitors have been installed for two weeks. The highs are indeed more crisp and reach a bit higher—at least that is what my aging ears tell me. I am really pleased with the result from this modifications. When combined with my use of the damping mat and acoustical foam noted in post #15, the result has been a transformation of the Bose system from a pretty good system to a very good system. Thanks Hoshi for a very low-cost and effective upgrade to the Bose .

Just finished all three mods, the foam stuffing, damping mat, and tweeter caps. Foam Stuffing By far the easiest mod. Easiest to stuff with the port tunnel removed -- just undo 2 screws holding the port in. I stuffed the box pretty full with pillow foam, getting it into all the nooks and crannies, probably a quarter to a third of a pillow. Bass was definitely tighter, went from -4 to -1 adjustment. Also now have surround turned to low. Big improvement. Damping Mat Also pretty easy. This did make a difference, again bass was punchier, less overwhelming, less flabby. Key is to ensure you don't block the 4 openings where the woofer hooks back onto the car. You're not going to get the sub back in the car if you put mat in those holes -- really I tried Tweeter Caps This mod took the longest, around 60-90 minutes. Most of that time was trying to get the tweeters out, and then removing the molex connector which was a real PITA. Not yet sure how much of a change it made -- caps might need some break-in time, as Hoshi noted. Highs do seem more pronounced, creating a more balanced sound. Not a huge difference though. 1] Removing the tweeters The metal tabs holding the tweeter in are very tough. Use the corner of an old credit card between the tweeter and the metal tab, and then pull the credit card up. That should bring one side of the tweeter with it. Then repeat with the other tab. The tweeter embedded in pretty robust plastic, so damage is pretty unlikely. Use the knob at the top of the speaker to pull the tweeter out. 2] Removing the molex connector This is a pain. Work slowly, and it will eventually come out. Took me at least 20 minutes. The way I finally did this was to wedge a small jewelers screwdriver into the top part of the connector, and pull the connector using some needle nose pliers. 3] Adding the caps This is not difficult, and is probably doable even if you have minimal soldering experience. Key is to heat the existing solder or wire, apply new solder, and then apply the new wire. Wrap the wires together (if you don't happen to have 5 hands), heat, and then add solder. The cap fits nice and snugly on the side of the molex connector, so you don't have to worry about finding space for it.

Hey Dave, Great photos and thanks for posting. Yeah, getting those tweeters out the first time is a real PITA. It look like you may have been able to get your tweeters back in without fishing the wires in first as your extension wire look pretty short. When I first soldered my bypass caps directly to the 4.7uf caps, I assumed that space was the reason on why I couldn't get the tweeter to seat back in place. It appears that my real issue may have been the bracket that holds the tweeter was just not accepting the tweeters properly. Anyway, I'm glad that the upgrade went well for you. As you described, the bass upgrade has an immediate improvement and very noticeable effect. The tweeter upgrade is a bit more subtle and as time goes on the bypass caps will open up and sound better as time goes on. Try jumping into a Cayman or Boxster with a stock Bose system and put a smile on your face. Hoshi

Hi Hoshi and others who have stuffed the port,I finally got around to removing the Bose bass unit to stuff the port and was surprised to find that the bass driver faces down and is in contact with the carpeted passenger floor so that the only exit for the bass pressure is the port which is almost in contact with the carpeted passenger foot area. The only bass pressure passing thru the port comes from the back of the bass driver.It's seems to me that even if the bass driver were a good one the installation contains the bass. Stuffing the port appears to further limit the bass but would reduce what little there is which if of low quality would be an improvement.This could be accomplished easier by simply unplugging the bass driver. Am I missing something?

Hey CBR The subwoofer pretty much just moves air and placement for a sub makes little difference that way that it is used in this application. In many true hi end installations, guys fire their subs from the rear trunk in passenger cars into the back seat. What a good sub does it lets you feel the music, most of the music that you think is coming from the sub is actually being generated from the woofers in the door of your car. The Bose sub in our cars in stock form is moving too much air creating over aggressive bass. By stuffing the sub, you are limiting the amount of air that is being moved and tailoring the lowering the frequencies and thus cleaning things up. When the sub is not stuffed, the low end is so over dominant that it drowns out the lower mid range and everything sounds muddy with loss of definition and clarity. What most people end up doing to compensate for this is to boost the treble. Once you get things dialed in correctly, you should use little if any treble or bass boost. I leave my tone controls at flat. Hoshi

Thanks for the original idea! I didn't need to worry about fishing the wires. I cut them short, and positioned the caps to the side of the central part of the underside of the speaker. So the cap sits perfectly right against the underside of the speaker. I don't recall any issue relocating the tweeter -- I do remember the tweeter is directional, so just made sure it was lined up the same way I took it out.

I got all excited to try this out since I've never been too impressed with my car's Bose system . Took off the sub and ......... it's totally different. This mod isn't for an '05 Boxster !

Hi Hoshi,After my last post,I decided to test my idea that the bass air pressure is blocked in the way the sub is installed in the Bose system . My idea is based on having two subs in my house that are sealed enclosures except for one bass port in each.One is an old Advent satellite system and the other is a Boston Acoustics Sub Sat Six.Both instruct to allow at least several inches of space from the ports.The Bose setup has maybe a quarter inch under the bass driver and maybe a little more from the port to the floor board but certainly less than one half inch. I removed the sub and cleared the port. 1.With the sub disconnected the sound was clean but short of bass.2.with the sub reconnected I played it on its side.The bass was now there but boomy and muddy.3.reinstalled w/out stuffing the bass was the same,boomy and muddy.I was wrong about the installation being the problem.It sounded the same not installed as installed.4. I removed the sub and stuffed the port various amounts but it made no difference to my ears.Blocking the port for me cured the boomy,muddy sound. 5.uninstalled or installed it seems to me the port is the problem so any method of blocking it is a fix. I used track 1 of Ben Webster's "Soulvile" to compare base. Do you agree with my thoughts?

CBR: All speakers including subwoofers have different crossover points. I'm guessing that your home subs have a higher crossover point that allow even some of the lower range of vocals to come through. When subs have a higher crossover point, placement of the driver is important as one can hear the direction or location of the sub. When subs have a crossover point that is lower, this is not the case as one cannot even recognize the music being played. If blindfolded, it would be impossible to distinguish the location of the sub. The subwoofer in the Cayman has a somewhat lower crossover point where location and direction in which the driver point do not make a difference. Stuffing the port changes the amount of air being moved and thus changes the amount of low frequency output. You need to experiment with various amounts of poly until you get what sounds right to you. I pretty much kept the space directly behind the 4x6 driver open and just stuffed the tunnel. Make sure that when you are tuning the subwoofer to have all tone controls on flat. I hope this helps. Hoshi

Hi there, Slim chance this will get a response seen that it is now a decade later but!😬 But: “VMax and adhered them tothe plastic sub enclosure as shown in the attached picture.” Anyone has a picture of this. Am a bit clueless how to go about here? Thanks!