BadjerJim

Well, there were a lot of positive comments about my idea for the Easy Bose Speaker Upgrade, based on Elmer's Carpenter's Glue. In my experimentation, I bought a second set of used speakers from another Forum member, so I dragged out the digital camera and repeated the process on those speakers. And took pictures along the way.

Important Note: Before you get to the part about the speakers, I want to chat a bit about Bose Corp, the Bose philosophy about sound, and Bose amps as they relate to the Corvette. Sheesh. If I don't put it here, it might be buried or hard to find amongst the other good tips here in this forum. So here I go...

Dr. Amar Bose is an audiophile, and his original Bose '901' speakers were the result of a lot of research. These were home hi-fi speakers, and were based on an array of 9 separate, and identical, 3.5-inch speakers. His (patented) idea was to use a bunch of small speakers that had great mid-range qualities, and then impose 'equalization' to punch up the bass and the treble - all from this array of speakers. No woofers. No tweeters. Just an insane EQ curve applied to all 9 speakers in the same enclosure. Weird, but it worked pretty good. Bose 901 speakers have gotten good reviews for the past 40 years! sheesh.

So when GM/Delco/Bose got together for car audio, it's no surprise that the same philospohy followed. That is: we have limited space for components (a car), and Bose knows how to punch the daylights out of otherwise unwilling speakers - to make them go far beyond the frequency range that they would otherwise do. How? With a specialized amp... that took the input signal, and then amplified it in a way that made puny speakers go far beyond their ordinary range.

So why do I go into all of this techy-boring stuff? Simple.

Fact is: sound quality from the stock Bose speakers in your Corvette depends on the amplifier that drives that particular speaker.

In the case of my 1990 Corvette, the previous owner had the Bose stereo 'repaired' by his trusted mechanic. This guy installed a 'generic' Bose replacement amp - one that would work with a wide-range of GM cars. And one that would sound uniformly crappy with any installation! Would it work? Yes. Would it have the special EQ characteristics for the particular speakers in my car? No!

How do I know this? Well, I got a call this morning from Doctor Don, where I'd sent my front speaker amps off to be rebuilt. His comment? "Jim, this is a Bose amp, yes, but not the right one for your car. Noway. I can rebuild it as it is, but it will sound like crud. With your permission, I'd like to rebuild it so that your stereo sounds good."

Wowza! A big tip of the hat to Dr. Don. He could have just sent me back a repaired amp, and I might have been as frustrated with the sound as others in this forum. So it's really important: make sure that your car has the correct Bose amps that correspond to the speakers in your car. 1991 and up Corvettes have 'plug-in' Bose amps. Any fool can buy an aftermarket 'Bose' amp, plug it in, and have it work. But the result will not sound the way that Bose, and their wild EQ-amp-customization-per-specific-car... noway will it sound like it did on the showroom floor.

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Enough about that. Now on to the procedure pics:

Important: Before you do any of this, remove the speakers/enclosures from your Corvette. I didn't include this step in my previous post because, well, I'm an old Geezer, and I couldn't even imagine doing this while laying on my back, under the passenger seat, twisted sideways, with a pot of glue in one hand and a brush in the other. Got it? Yank the Bose speaker enclosures out of the car, and put them on a good work surface, like in the following pics. Okay? Okay.

In my previous post, I described mixing Elmer's Carpenters Wood Glue - about 2/3 glue to 1/3 HOT water. HOT water makes it easier and faster to mix,and make for a more uniform stuff to spread. Stir it up good. Here's a pic of about half of a front speaker 'painted' with this mixture:



Next is a pic of the front speaker evenly coated with the glue mixture. Note that it's okay to 'paint' the center Also note that there's some 'run-off' down to the center of the cone. This is normal:



Finally... give it some time... maybe 15 minutes or so. And then 'brush up' the pooled glue near the center of the cone. The idea is: you don't want a big pool of glue-glop near the center of the cone. Brush it up so it looks like this:



For the front speakers in your Bose/Corvette: do not do this to the smaller 'tweeter' speakers. No. Never. Do not. They're already covered by a fine 'mesh' material. Don't be tempted to pull it off and do this glue-treatment to the tweeters.

Rear Speakers
This is very much the same as the front speakers. I've included these pics only because.. some previous owner (or related 'mechanic') removed the 'kick plate' grill over the front speakers. Bad. So here's some pics of the Rear Speakers, and their related BadjerJim Treatment:

This pic shows the 'kick plate.' Kind of a grill behind the speaker grill:



Remove it so it looks like this, for the treatment:



Brush away with the glue mixture, so the rear speaker ultimately looks like this:



Semi-Important Misc Notes About This Procedure:
1) Realize that the idea here is to 'stiffen' the cone of the speakers. It's okay to get the glue-mixture onto the center (what's known as the 'dust cap') of the speaker.

2) You don't want a big puddle of glue down in the center of the cone. This adds weight/mass. A small puddle, as shown in the pics, is okay.

3) Let the glue-mixture cure and harden in at least room-temperature environs, for at least 24 hours before you test the result. Realize that a big part of this process is letting the hot-water-glue-mixture penetrate the paper of the Bose speaker.

4) Finally... a second coat of the glue-mix probably will not hurt, and may actually help. The overall result will be to make the speakers sound more like Infinity 'poly' speakers. You may or may not like the result. Adding layers of glue will make the speakers sound more 'plasitcy'. Is that a word? Dunno. But for sure: they will be louder and punchier. Don't go beyond 2 coats: that will just weigh down the cones of the speakers, etc.

Feedback please!

CG77VETTE

I will be performing this procedure on my 20 year old speakers over the winter. The one observation I have is that I think it would be easier to just remove the speakers from the enclosure as opposed to removing the entire enclosure. The rears are not too bad but the fronts require removal of the door panel which could be quite a workout. Simply removing the speaker covers gives you access to the screws holding the speakers in the enclosures. Unscrew the speakers and disconnect the wire harness and it comes right out. Just my $.02

bogus

I agree with your assessment of Bose and Dr. Boses' philosophy.

However, a few added thoughts:

1) To me, it's like the systems are truely designed to reproduce a limited type of music. From my estimations, classical guitar is the best music for the bose system.

2) It's even beyond equalization... it's about torturing air. The porting does just that - torture the hell out of the air. I was checking out the demo sub module for their home systems at a Bose store a few years ago... to start with, the sub seems to run outta gas at about 50~60hz... weak. However, the sub module has 2 6" (nominal) drivers in it. These drivers are tuned (equalized?) to run at an optimum rate, somewhere around 1500 hz (visual estimate) and the porting slows the air down to emulate bass.

3) Their drivers are JUNK. I personally like paper cones, but coated paper (what you are effectively doing) is the best compromise. I really am not all that impressed with plastic cones, but I do like the new kevlar cones - the kevlar seems to have the warmth of paper, but with better environmental protection and greater strength.

4) The latest bose amps actually ARE an upgrade. They are supposedly more powerful than the OE pieces.

Bottom line? It's overpriced junk.

BadjerJim

Um, Bogus... you're way off on this one. You are well known and respected here on the CorvetteForum. But in this case, I just have to call out on a few of your points:

1) Classical guitar music? No, the whole point of the Bose EQ at the amp idea is to produce a wide range of tones from small speakers. As I found in my car, you may have had 'generic replacement Bose amps' in your car and never known it. Oh yeah: it made noise and got semi-loud, but was entirely the wrong EQ for the speakers in your car.

2) Comparing Bose home speakers vs Bose Car speakers? Way off base. A home speaker environment is based on large rooms - very different from the cockpit of a C4 Corvette. How many cubic feet of air in a C4? Very small, compared to even the smallest living room in a house. Apples and Oranges here.

3) The Bose drivers (speakers) are NOT junk. Actually, they use good composition paper cones (that I explained how to strengthen), and use aluminum bobbins for the voice coils. This provides good heat transfer when used at high volume - and prevents 'burn out' when things get hot (the heat has someplace to go). Junk speakers, in comparison, use paper bobbins. In fact, with my past High-End Home HiFi speaker company, we used the same Bose 3.5-inch driver in several of our models - as a MID-RANGE driver. We never pulled it up or down from its inherent tonal range. We found the 'surround' well matched to the stroke of the cone, and found the 'spider' (what keeps the voice-coil aligned at the rear) was ideal, without interfering with the stroke or resonance of the speaker. To make it a true HiFi speaker, we injected ferro-magnetic fluid into the air-gap at the voice-coil. This further improved heat-transfer from the voice-coil to the magnet structure, and thus improved power handling. But again: realize: we're talking about hundreds of watts of clean power in a home HiFi system. Not a car system.

4) The latest Bose amps are NOT an upgrade. They are generic amps, designed as a compromise for a wide-range of GM, Nissan, and other manufacturer's cars. In my case, NOBODY is making brand new Bose amps for a 1990 Corvette: for the front speakers. Nobody. Nada. Zip: nobody. How could they? What's the demand?

(Side note: Dr. Don's knows all about this. Call him and ask about what I've just described. He'll agree. I'm trying to describe here, to you, what Dr. Don has problems describing to new Corvette owners, trying to repair their old Bose systems. Dr. Don's: 936-435-1811)

The latest 'brand new' Bose amps represent the crulest form of compromise: they plug in, they work, noise comes out of the speaker... and for the repair guy, the mechanic who installs them... everything is fine. But they don't have to listen to them, or live with them on a daily basis! That's why I wrote the long pre-amble about Bose amps, and how they interact with the specific speakers in a particular car.

I'm not trying to pick a fight. I'm just trying to help here.

BigDR

I try to remember this is 1990s technology - still sounds excellent to me.

bogus

I knew I shoulda precursed my comments with "opinion." But I forgot. I will also precurse these comments with this: I am not a speaker engineer, everything I have learned has come from reading and sampling products... and installing more systems than I can count!

I understand that is the goal... it's just that I don't agree it works.

I have listed to a ton of music on my, and other, car based (and home based) bose systems. The best sounding music is classical guitar. Anything else is lacking. Either in tonal depth or in range. Your own comments about using their 3.5" drivers as midranges confirms my feelings on this. No matter how you torture the signal or the air, the speaker has a natural frequency where it works the best...

Not really. The same philosphy applies. And interestingly, at least to my ears, the same overall sound signature. No matter where I am installing my system - home or car - my goal is basically the same: emulate the pure sound imaging and warmth of a quality set of headphones.

My home theater is a Yamaha/Mirage system. It cost about $1500 back in 2000. It is half the price of a Bose Jewel based Lifestyle system, and blows it away in every measure my ear can apply - I really wish I had a spectrum analyser.

But my ears are VERY sensative to SQ.

That's an interesting observation. I have never had a lot of respect for the bose drivers, simply because they always looked like junk when I saw them - and many were not that old. The paper was a bad idea for the car environment. Add in a questionable surround... it's not a good mix for the car.

I removed the bose from my Vette about 5 years ago... and then, the bose drivers looked (and felt) WORSE than the 10 year old Cantons I have in the car now.

To reiterate, using their 3.5" drivers as MID RANGES is a good idea... it sounds like where the speaker SHOULD be used... it comes back to the way they torture the air with the porting.

I have found that most of the time, a home system does NOT need as much power as does a car system. The noise floor is not there in a home environment, where 70 or 80 watts will do it.

Infact, in the super high end of home audio, where they make tube amps the size of coffee tables... and these systems only put out 30 watts per side.

I stand corrected. The words from Bose implied they were an "upgrade." Great...

His web page is linked in the C4 Audio FAQ.

That really sucks.

No, not at all! It's all about discussion and the exchange of ideas/opinions.

My 92 has Canton three-ways up front...



Trust me, these sound a ton better than ANY bose...

Jeffvette

I agree with Bogus. Bose is nothing but garbage. Home or car audio.

The audio system was the first thing to go out of my car back in 2000. Funny hting is, that my aftermarket MBQ and alpine headunit (which is from 97) has lasted better than a friends rebuilt Bose set up.

There is a reason for the phrase "No highs, no lows? It must be Bose"

cv67

I bought an Acura RL 3,5 a few years back for the ex and I have to say the BOSE system in there sounded awesome for a stock system, I was surprised...although I suspect it is a better model than what ever GM was installing. ! In general though (Vettes, my truck) Im not super impressed. If you really like your music and like it cranked get an aftermarket. JMO.

JrRifleCoach

I try to remember this is 1980s technology - still sounds excellent to me as well. This mod will help sharpen the sound some. Now I'll spend my money on go-fast equipment.

Thanks for the tip!

bogus

The problem is that it's a continuing problem. I think the early C4 Bose actually sounds BETTER than the later version. The speakers are higher up and the mids and highs can be heard.

In reference to it being a continuing problem... even NEWER bose systems sound weak. I listened to one in a buddy's SL500 Benz, and once it got cranked, it became VERY annoying. The best sounding bose was in a Maybach... gee, I wonder why?

wilsonbh

I like is so much that I plan to pay Dr Don's fee and get the CD repaired and upgraded.

I enjoy music but don't need the volumn to peel the paint off the car beside me at the stoplight.

I have a hard time understanding the need to add these huge amps and additional speakers to a revamped system. To me, clarity is the key to good music, not volumn.

But I fully admit I don't have the background of Bogus and others here on such matters so what do I know!

I do see the general mood of this forum is anti-bose. I understand this as Bose seems to be overpriced for what it does, way overpriced. So much so that they price themselves out of the market. This is the biggest issue I have with them.

For now, I'll get my HU rebuilt and try to hold onto my stock setup.

Billy

topgunvette

thanks for the detailed write up/pics, i am going to replace my speakers regardless but before i do i will give this method a try having no expectations of course, thanks

Strick

After 35 years of flying jets, I don't have the hearing I once had. I find myself saying "what did you say?" a lot. I appreciate the well written tip for improving our Bose speakers which to me sound just fine. If this helps blast out my favorites, like SRV, Hendricks and Heuy Lewis, then I'm going to try this out. I had Dr. Don work my rear amps and they sound great to me. I still like the sound of my Vette with the top down and the exhaust rumbling down the road. When the top is up, on comes the tunes. Thanks again.

Kwikerthanu

Not to hijack this thread, or throw water on the picnic, but instead of the Elmers Carpenters glue, couldn't you use Future acrylic floor finish? It's thin like water, dries fast, and is tough. It's actually a waterbased paint. Just a thought.

65Z01

Indeed I'd be curious to hear comments on this potential "option" to stiffen the stock Bose speaker cones...

AORoads

My opinion of Bose is not as sanguine as yours, BadgerJ. But I do appreciate the update and the pictures which help a lot!

I've had 3 Bose car systems, two of which were brand new. One in a '93 and one in an '03 and now this one, a '96.

They have all been uniformly bad by comparison to anything I've heard. I'd rather have an el cheapo, no-name, standard "stereo" in my car than pay for a supposedly upgraded Bose.

And one of the cars that I owned was a luxury car with this as its upgraded system. Awful, just awful.

You can state your belief/impression that it's the amps or the cones or whatever including the cabin config or the wiring but the fact remains, other cars with other systems are far better. A standard, non-upgraded Lexus system if you've heard one from the late '90s is so superior it's as if the Bose is a cheap boom box. And yes, it's not apples to apples: a late '90s luxo barge compared to an '03 luxo barge---and the '03 loses with its upgraded, designed for the car, Bose.

Granted I'm not an audiophile and the buying public just keeps on buying them. But i would not. At any price.

jmo, and we all have one or more.

Impala Balko

I honestly feel like a minority here because I actually like my bose unit mine for the time being works flawlessly the bass hits hard (well hard for a non Subwoofer system) the highs are where they need to be and the mids are good too. My only complaint is when listening to talk radio such as "Howard Stern" or "Bubba the love Spounge" the system sounds too bassy and it actually gives it a muffled sound so it can be tough to understand sometimes. That is why I hope this mod helps that. other than that i think the sound quality is great and really fills the cabin out real nice and I listen to everything from classic rock to hard rock, to pop, hip hop, r&b, little bit of techno, hell i have even put classical music on and it all sounds good in my car... that is why i dont understand why everyone hates on the bose gold

BigTexas

No problems with my Bose either! I like it!

teebee

I'm with ImpalaBalko. I'm no audiophile, but the sound that comes from my system sounds good too me. I am going to do this modification to my speakers in an attempt to "brighten up" the talk broadcasts.

quantum-theory

Cars are an awful environment for sound, especially our noisey C4s. At my age, do I really care about the highs? I can't hear them anyway as a result of age and too many 60's concerts. Many years ago I was nuts about sound,even going to the extreme of paying $700 (this was in the early 70's) for just a tone arm. I think it is now time to be sensible. The car came with the system, it sounds good to me, I'll keep it. Thanks for the tip on stiffening the driver cones.