Before I say much, please let me explain, that I have many years in the electronic audio repair and listening business. Most of my experience goes back some years, but have fooled with product enough to get a sense of decent audio sounds. When in the profession installing quality systems in Colorado, we learned that you could have the greatest system in the world if you were willing to spend enough money. It has not changed today. And, too often there seems brand loyalty or non-loyalty based on the loudest marketer! My roots carry me back to the early days of Altec Lansing and JBL. Anyone in the audio profession realizes the quality of such product in its time (And still today!)
Typically I have never been a Bose fan. My experience suggested these systems were too synthetic and “cosmetic” and lacked presence and dynamic range. They too, were often over priced in my opinion. One cannot compare a quality home system to a car audio system simply on the basis of a whole different sets of environments.
I have read for hours with interest on posts of those who love their Bose and or Monsoon systems in the Bonneville and a good hunk of those who tear the system down using adjectives to describe Bose as “junk”, “terrible”, etc. When you look at the system, with cost, mass production, and “reasonable” sound as criteria to create audio for the automobile I believe they did quite well. So, I thought how could I improve on the system because I wanted to keep the dash look, the steering wheel controls, and not spend a fortune to convert. Now I know you can purchase all of the devices to continue use of your steering wheel controls, a converter to install that new head unit, a new head unit, a new sub-woofer with a sub amp, a new set of at least four or six speakers, an expensive aftermarket equalizer to rework the EQ of the Bose head unit, and the many hours of labor. So I set out to try to improve upon what I had in my 2001 (Bose) and 2003 (Monsoon) “Poncho Bonnies”.
The criterion at the outset was to create a sound that delivered a dynamic range presentation with presence and clarity. I further wanted to create the strongest presence in front with the ambient sound coming from the rear, which I believe is the best stage setting for listening pleasure. Our Bonnies are cruisers; loud earth shaking bass that rattles the trunk becomes tiring in time. I do not need to impress my neighbors by my purchase but rather enjoy the sound in the cabin of my Bonnie that is pleasurable over a longer period of time while I am cruising! (My current adjustment to the Bose with minor additions still vibrates the rear window if I turn it up without distortion!) So I set out to improve. I am pleased with the results and saved many hundreds of dollars!
First of all I replaced the front speakers both 6 ½” and tweeters with JBL GTO speakers. I could position the tweeters to point directly at myself in the cabin, thus direct radiant high presence. The combination of these speakers gave me 2 ohm impedance. Left the rear door and rear 6 by 9 Bose speakers in place secondly installed a 12” JBL quality subwoofer and JBL power amp, and connected the units to the line out rear speakers off from the Bose head unit with a converter. The wiring for the amp was very simple as the trunk is so close to the rear where the battery is located. I further tapped into the power (pink) wire that runs to the trunk. All of the wiretapping from the Bose head unit was completed in the trunk where the wires run into the Bose power amp. I stripped back the wires and wrapped them with those needed to hook up to the converter and soldered all of joints for long term reliability.
Now the trick was balancing the HU with my present inventory. (Some of this information I secured from a GM post)
I found I could set the volume at 4 or max 5 bars for a very loud listening experience. I did not need to go any louder. Above 5 was UN pleasant to my ears. I was getting good sound without a lot of EQ boosting on the HU. Seems the best dynamic transparent sound quality is at 4 or nor more than 5, depending on the source (CD, radio, IPHONE) levels. You may want to play with this a bit but typically many set the EQ on the radio at +6 Treble 0 mid and +6 on bass. You will get a poorer quality sound with these settings because of the “cut-Off” curve built into the Bose HU. Please NOTE: the HU does not increase bass from “O” with volume increase, built in limiters in the EQ, but it does increase the highs as the volume increases! The peak frequencies for the HU bass are 50 HZ the peak on the mids is 635 HZ and highs is 12K. (I did not measure this but secured the info from a GM post). These are the frequencies when the bass, mid, and highs are increased or decreased within the HU). Thus it seemed logical for me to try and blend what I had to create a dynamic transparent sound. Realizing the bass does not increase with the volume from a low setting, I realized the adjustment for bass would have to come from the sub, so I tuned the sub to maximum output without distortion. (Realize many of the Bose or JBL GTO speakers would not go low enough for a clean bass boost at higher levels. Thus I let the sub take the lower frequencies. Now knowing that the treble and mids would increase I needed to adjust them just the same on the head unit. Each system will be different and has to be played with. I finally set my system with following on the HU. Set the bass at a -4 (with this setting your bass will increase proportionally with the volume and sub presence-sub set at maximum NON DISTORTED OUTPUT), the mids at -2 and I chose the treble at +6. (I like the crystal clear sound of the JBL tweeters at +6 for some they could be set down). I now can turn the radio up to levels that are unpleasant to my ears without distortion. The highs are crystal clear the mids mixed well, and bass very clean clear and transparent with the body of the music. I am very pleased with the results for the low level labor and cost.
Thus in a nut shell.
Add quality speakers in front-Match the ohm in the Bose system for maximum DB output (Third party experts on the net rate JBL higher than the JL, Rockford Fosgate, Alpines and other "popular" brands) (Third party may be more reliable than Johnny's view down the street)
Add a quality sub-woofer and amp
Adjust the EQ’s of the HU and the sub amp
Sub set a max output WITHOUT DISTORTION!
Bass set at -4
Mid set at -2
Highs set at +6 or a little less depending on your wishes
And enjoy!
Post script. I am sure there are many who will say this does not work. Here was my thinking. I will start with this 1st level and add to each stage as I need to get better quality sound. If I started with quality product, I could always add new rear speakers, a Head Unit, an interface unit for the steering wheel controls, an interface unit for the new head unit, and on and on. I could spend many, many extra hours in creating this system. Well, in my judgement I did not need to do so. I am very, very happy with the hidden quality that really is already there with Bose and Monsoon. I believe I just needed to readjust that quality. My neighbors down the street may not hear me but I sure enjoy the pleasant sound in my cabin when I play Boston, Cusco, Mannheim, Pink Floyd, The Doors, and yes even BOB DYLAN!,and the many, many great musicians! The last I checked my hearing was still ok and I am in my 70’s!!!! Happy Cruising in one of the greatest cars in my opinion on earth-The Bonnevilles! What a great site!!!