Adding Tweeters to C4
Thread Starter
Racer
Joined: Apr 2017
Posts: 396
Likes: 58
From: Katy Texas
Adding Tweeters to C4
The car is a 1989 with original Bose system and rebuilt amps from Dr. Don and appears to operate normally. The speakers are original and might be tired, but they look healthy. The system suffers from that typical "fried egg" sound on the highs and grows tiresome after awhile.
I am considering adding good quality stand alone tweeters to the front with built in crossovers. I need advice on what to put inline to filter out the highs on the stock Bose 4 inchers so all they have to produce are mids and whatever lows they can. Can anyone point me to something? Are there passive filters that will do this?
For improved bass, I am adding a powered enclosed sub-woofer in the hatch area.
I am considering adding good quality stand alone tweeters to the front with built in crossovers. I need advice on what to put inline to filter out the highs on the stock Bose 4 inchers so all they have to produce are mids and whatever lows they can. Can anyone point me to something? Are there passive filters that will do this?
For improved bass, I am adding a powered enclosed sub-woofer in the hatch area.
Racer
Joined: Oct 2011
Posts: 388
Likes: 38
From: Madison CT
You can design a simple 12db/octave passive filter to low pass the stock speakers and high pass your tweeters. You need to look at the specs for your new tweeters and the bose midranges to decide the right frequency to crossover at. Here's a good starting point, but there are lots of crossover calculators available online. See below:
https://www.google.com/url?sa=t&rct=...5EYEqW_s6qtEGU
http://www.erseaudio.com/Second-Order-2-Way
https://www.google.com/url?sa=t&rct=...5EYEqW_s6qtEGU
http://www.erseaudio.com/Second-Order-2-Way
Thread Starter
Racer
Joined: Apr 2017
Posts: 396
Likes: 58
From: Katy Texas
You can design a simple 12db/octave passive filter to low pass the stock speakers and high pass your tweeters. You need to look at the specs for your new tweeters and the bose midranges to decide the right frequency to crossover at. Here's a good starting point, but there are lots of crossover calculators available online. See below:
https://www.google.com/url?sa=t&rct=...5EYEqW_s6qtEGU
http://www.erseaudio.com/Second-Order-2-Way
https://www.google.com/url?sa=t&rct=...5EYEqW_s6qtEGU
http://www.erseaudio.com/Second-Order-2-Way
I found some nice Focal 1.5 inch tweeters with flexible mounting that have a frequency response range from 4,000-21,000 Hz. Built in crossovers. I'm going to get someone smarter than me at Parts Express on the phone and see what they say.
Thread Starter
Racer
Joined: Apr 2017
Posts: 396
Likes: 58
From: Katy Texas
Yes, they come with built-in crossovers. They are 4 ohms, however, so I am curious how they will behave wired in parallel with the Bose amp, which is also driving the 1 ohm Bose speakers. I found an online tool that calculates 0.80 total ohms across them both. We shall listen. Parts Express has recommended an appropriate air core inductor to filter 4000hz and above on the originals and turn them into mids. I don't think they produce much bass in the first place. I'll report back when I get them installed.
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Thread Starter
Racer
Joined: Apr 2017
Posts: 396
Likes: 58
From: Katy Texas
So, 3.5 months later and I can now report my results. Other projects got in the way.
My goals were to keep the stock system, improve sound quality, staging, get rid of that Bose "fried egg" sound at the high end, and add some real bass. Hope someone finds this useful/interesting.
Here is the work I have done on my original 89 Delco Bose system:
Original Bose 4.5 inchers from the 901 are reported to be used in this DelcoBose application. Their range is reported to be 83 - 15,000Hz using the Bose equalizer.
New ranges:
Kenwood Sub = 35 - 125Hz. I have the crossover set at 125.
Bose Mids = 83 - 4000Hz
JL Tweets = 3.6 - 22,000Hz
I'm calling this a success from my perspective. I'd enjoy hearing any comments/suggestions.
Now, let's see if the system holds up!
My goals were to keep the stock system, improve sound quality, staging, get rid of that Bose "fried egg" sound at the high end, and add some real bass. Hope someone finds this useful/interesting.
Here is the work I have done on my original 89 Delco Bose system:
- Dr Don's rebuilt original Bose amps at each speaker unit.
- Two watery thin coats of Elmer's wood glue on each speaker cone to stiffen them up. I find paper cones too warm, you may not.
- Inline Jantzen Audio 0.025mH 18 AWG Air Core Inductor Crossover Coils at each positive speaker terminal to filter out 4,000Hz and above. This specific unit recommended by Parts Express.
- JL Audio C1-100ct 1" C1 Series Component Tweeters in the front doors right next to the original mids. None in the rear for now. Tapped right into the speaker leads.
- Kenwood KSC-SW11 Compact Powered Enclosed Subwoofer in the rear. Tapped into the driver side Bose speaker leads only. Bass response is pretty good.
- I think my attempt at making the units mids-only has worked. Adjusting the treble slider all the way up on the radio does not produce any sort of highs, just adjusts the mid ranges. And the things didn't produce that much bass in the first place.
- The new tweets are amazing and they have really improved the sound staging in the driver's seat. I have the fade biased a bit to the front. I am now hearing instruments that were not produced before.
- The subwoofer has really rounded out the system and there is real bass in the thing. Would I get more bass if I tapped into the passenger side leads?
Original Bose 4.5 inchers from the 901 are reported to be used in this DelcoBose application. Their range is reported to be 83 - 15,000Hz using the Bose equalizer.
New ranges:
Kenwood Sub = 35 - 125Hz. I have the crossover set at 125.
Bose Mids = 83 - 4000Hz
JL Tweets = 3.6 - 22,000Hz
I'm calling this a success from my perspective. I'd enjoy hearing any comments/suggestions.
Now, let's see if the system holds up!
