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Discussion Starter #1 (Edited)
I'm not a huge audio geek, but I do want the sound to be better in my LT, because I bought it and plan to keep it for a long time. The sound from the stock speakers in the LT version is pretty terrible. Is there a simple and not too expensive upgrade that you can suggest?

(I checked out the existing threads already. The complexity of the solutions mentioned were more than I'm looking for.)

I've never done car audio upgrading work myself but I'm fairly handy and am happy to do the work myself if it's not too hard. And willing to hire someone to do the work if it's not too expensive.

Thanks! I like my Bolt a lot and just want to get this one thing upgraded.

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I've been playing with speaker upgrades - got improvements, yes, but not the results I'm looking for... yet. I'll post parts lists once I have satisfied that's I've nailed my design.

The tweeters are easy to replace - the side panels along the dash sides pry up easily to reveal where they hold down the tweeter grilles. There is also plenty of room under the tweeter for a good crossover. I'm about to try my second tweeter for the sound I'm looking for.

Suffice it to say that some really good tweeter are available at Part-Express for under $20 each that fit the 42mm mount of the factory unit.

I'm also working on an inexpensive upgrade to the rear door speaker to act as pseudo subwoofers. Hopefully all the parts will go in this weekend.
 

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I'm also working on an inexpensive upgrade to the rear door speaker to act as pseudo subwoofers. Hopefully all the parts will go in this weekend.
Surely, there is a subwoofer in the trunk, under the charger dock. It looks like a subwoofer horn to me, and it says BOSE on it. There is also an amplifier with cooling fins bolted down next to it.
 

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I've been playing with speaker upgrades - got improvements, yes, but not the results I'm looking for... yet. I'll post parts lists once I have satisfied that's I've nailed my design.

The tweeters are easy to replace - the side panels along the dash sides pry up easily to reveal where they hold down the tweeter grilles. There is also plenty of room under the tweeter for a good crossover. I'm about to try my second tweeter for the sound I'm looking for.
I am not keen on BOSE. The company has its own ideas about frequency response and what sounds right, with the results that we hear in the Bolt EV. If you start messing with the speakers, I am not sure you will obtain many improvements, because its the electronics and crossovers built into the system that control the sound. I really don't know for sure, but I suppose these things are built into the preamps of the system, and the speakers are just victims.
Its my view that the midrange is the problem. I find it to be muddy when music is played, although talk shows sound fine.
 

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I have the Bose system in one of our Gen 1 Volts and it's really impressive. Except a few narrow frequency bands where distortion spikes (cone edge resonance?) it has terrific imaging, frequency response, and can get plenty loud.

For my Bolt EV, I went LT — no Bose. I didn't care the Bose in the Premier, either. It's just not at the level of the older Volt design.

Without getting into the gory details of crossover design and driver choice, my first design had two goals: low distortion and a better sound stage. I got better sound stage, but the dash driver I chose spikes some distortion that hurts my tinnitus and it can't play cleanly above about 30 on the volume meter.

This weekend I plan to install my 2nd design that backs away from the sound stage emphasis somewhat to just get the distortion as low as possible... It'll be based on Dayton Audio ND28F-6 (if I can get these larger tweeters to fit the dash), Scan-Speak 16W/4434G00 already installed in front doors, and Dayton's DC160-4 in the rear to be subwoofers of sort.

I'll keep you posted. If I can it dialed in the way I want, I will post a detailed parts list, including a possible Dayton alternative to the Scan-Speak, which is an excellent but hard to find, plus rather expensive driver.
 

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As for the Bose subwoofer - yes - there is one in the trunk if you have the Bose option on a Premier model. I didn't... I got an LT, which lacks bass and has a fair amount of distortion pretty much all over the spectrum.

The Bose has better bass than the stock sound system, though to me it felt like it was "disconnected" - I kept feeling like it was coming from the back of the car instead of integrating with the rest of the sound. I didn't care for the stereo imaging of the tweeters, either.
 

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I don't know how any speakers can create a soundstage in a car at all, at least compared to a good speaker system or my personal - electrostatic headphones*. Recordings are mastered with (at least) a pair of monitors in an optimal position (equilateral triangle). On the Bolt there are a pair in the far dash corners pointing up at the windshield, and the two front passengers are offset from center, which is the same pattern in most cars AFAIK. No DSP I know of can fix this. You can fake it somewhat, depending on the recording. To my ears well recorded single vocals (or other relative mono sources) sound really good, as you'd expect given the simplicity of the spatial recording and the simplicity of the signal. An orchestra on the other hand sounds like a flat generic wash. At that it's fine actually, when I'm driving its not like I've got critical ears on.

* before anybody tells me recordings aren't optimized for headphones either I'd agree, and then tell them I have rare diffuse field equalizers optimized for my (Stax) headphones. These give excellent linearity and imaging.
 

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It's amazing how well the ear/brain pick up time delays and frequency cancelation to discern direction and distance of a sound. Yes, a car is a poor environment for stereo imaging, or sound quality at all for that matter. But the key to getting at least some sense of space in the music is to use quality comments that precisely match each other and to get low enough frequencies from the dash or A-Pillar speakers so that the upper midrange frequencies most capable of triggering directional response are close to eye level instead coming from the floor. It's by no means perfect, but it can at least be better. My research and bit of research through a few rounds of experimentation is to get frequencies over 2,500 Hz up top.

My project is done and I'm happy with the results. The Dayton ND28F-6, $23 each from parts-express, is about the largest tweeter that could possibly fit -- barely able to squeeze the faceplate with the thicker tweeter mounted back into the corner of the dash beneath the windshield. But it so worth it! The clarity and smoothness of frequency response is much better. The lower crossover frequency afforded by a larger tweeter definitely gives a perception of the sound coming from in front of you instead of from the doors while avoiding distortion.

The tweeter itself is 1-2 mm wider than the factory mount on the underside of the faceplate. This is after removing the new driver's factory flange. To make it mount, I had to modify the Bolt's tweeter faceplate by cutting the round mount like flower petals to stretch it around the wider driver. I then used heavy duty duct tape to reenforce it around the outside ... hopefully it will hold together long term.

The larger driver (1-1/8" vs 1 ") is somewhat less directional at the very highest frequencies. This is actually a good thing, cutting down on reflections and allowing the two tweeters to be heard more from a direct path instead of echoes against the glass. I am very satisfied with the results.

For a crossover I have a 10Ω 10W resistor in parallel with a 0.25mH air coil, plus an 8.2µF polypropylene capacitor in series in front of it. This give a crossover at 2,700 Hz - a bit lower than typical of a tweeter. This heavier duty driver can go that much lower without distorting the low frequencies. I soldered the crossover parts together and wrapped each in 1/2 inch low density foam so that they won't rattle once stuffed down into the dash.

The front doors are Scan-Speak 16W/4434G00 drivers that have excellent low frequency response and low distortion. The lowpass crossover for these are 5.1µF poly capacitor plus 0.55mH air coil. I think you can get similar results from Dayton RS150-4's for less money, although they wouldn't have quite the bass presence.

The rear drivers ara Dayton DC160-4, with 2.5mH air coil lowpass filters. These reenforce the bass and also lower midrange that tends to be absorbed by seats in the car. They do not draw the sound stage backwards, avoiding that headphone-like "inside my head" feeling that sometimes comes from rear speakers. Although some folks may like that effect -- this would probably not be the real setup for you.

I shot video and stills of the process. I may be able to get some tutorial materials together. It was time consuming, but actually access to the speakers isn't that bad... And I think this sounds better than the Bose option for less money. All told, I spent about $360 in parts (exlcuding some bits on the shelf from experimenting...)
 

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Great post, Gary - it's a little over my head in terms of the audiophile stuff (I understand the electrical engineering of it but not so much the practical and design considerations), so I'm looking forward to seeing some of the video you shot.

I've got the Bose upgrade in the Premium trim, and to be honest, I find it to be a little underwhelming. I haven't done any scientific tests, but I *think* it's missing some decent response at the low end just above the sub range, and maybe going up into the lower midrange a bit. Like maybe the sub crossover is too low or maybe the drivers are a bit weak? Anything that's low enough to make use of the sub is actually a little too punchy for my sedate tastes, though.
 

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Alas, my footage was out of focus for a lot of what I shot... It was tough to be shooting my own hands doing the work. Aside from my cushion video, I provided a very short guide to getting the door panels removed, but that was about all that turned out. Sorry!
 

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As for the Bose subwoofer - yes - there is one in the trunk if you have the Bose option on a Premier model. I didn't... I got an LT, which lacks bass and has a fair amount of distortion pretty much all over the spectrum.

The Bose has better bass than the stock sound system, though to me it felt like it was "disconnected" - I kept feeling like it was coming from the back of the car instead of integrating with the rest of the sound. I didn't care for the stereo imaging of the tweeters, either.
In my premier Bolt, I am finding the Bose bass to be annoying, how it will suddenly push out a strong low frequency burst when someone on the radio pronounces their hard consonants, and yes it is disconnected as you say.
 

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Another update:

Today I added sound deadening to my car's doors. The car is now quieter, and the bass is better. I believe the doors had been acting as an echo chamber, causing some frequencies to cancel out while others were too loud. It took about 15 hours and $150 worth of foam products. But it's worth it. Details are on my blog: http://www.aulfinger.us/CurrentCars/2018/2018-02-11.html

Gary
 

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There aren't many times where I am happy that my hearing isn't that great, but I hadn't noticed that the LT sound isn't any good.
If/when I get some hearing aids, I may change my mind.. ;-)

desiv
It's actually OK. Some people just like to modify their cars.
 

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Thanks again for the additional info @ Gary.

I got my package from parts-express yesterday, just need to find some time to work on it now! :) I'll try to take some pics.

Regarding original stereo, I'm a little spoiled, my prev STS had a really nice Bose system. It was actually the first car I ever owned where I didn't touch the audio. The Bolt's is alright, but I do hear the shortcomings and hoping to bring it a little closer in capability.
 

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Surely, there is a subwoofer in the trunk, under the charger dock. It looks like a subwoofer horn to me, and it says BOSE on it. There is also an amplifier with cooling fins bolted down next to it.
To the extent that a 6-ish inch long-throw speaker can be called a "sub" woofer, yeah, it's there. If you search eBay for "CHEVROLET VOLT SUB WOOFER SPEAKER OEM VOLT BOSE SPEAKER AMP", you'll find a part that, other than the amp mounting, looks very similar to what's in the Bolt. I didn't remove the thing, but there's enough room to feel up the speaker a bit, and it feels like what that item looks like.
 

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I have had more questions privately about my speaker mods, so I have added a number of photos to my blog to show more of what I did: http://www.aulfinger.us/CurrentCars/2017/2017-11-12.html
@gaulfinger Hey, I was trying to follow your description of the crossovers, and this is what I came up with. Does this look right (attached image - revised 11/3)?

I'm having trouble following on the crossovers. On the plus side I've learned a lot about them in researching this.

Assuming the diagram is correct, a few questions:
1) What's the purpose of the 10 ohm resistor on the tweeters? Is it to make this 6 ohm tweeter look more like a 4 ohm (although I'm getting 3.75 ohms with them combined)? Or is it to attenuate it?

2) Every site with some kind of crossover calculator fails to come up with anything near these values for the components. For example, if I plug these into: https://speakerwizard.co.uk/calcs/Crossover_Calc_v2.php , I get a power response with a large dip around 2700. Of course this isn't using data from the actual speakers. I found a very advanced looking excel-based calculator but it was still a bit over my head. I guess, I'm trying to make sure I do this right, but I'm not really able to confirm it because nothing I find suggests the values of these components.

If I use the above crossover calc v2 and tell it I want a crossover @ 2700 hz it's saying use a 10.44uF capacitor and 0.34mH inductor.

Could you or someone fill in some of these blanks? Thanks!
 

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Alright, I jumped right into this. I replaced the tweeters in the dash and front door speakers (using 2x RS150-4). The speakers in the rear doors are still stock (DC160-4 was on backorder). I'm using the above schematic. I have to say, it sounds amazing! Before, depending on the type of music, over 30 could result in messy, distorted sound. Now it goes to max and it's clear, loud, full and crisp. I feel like having the DC160-4 in the rear doors to reinforce the bass is just what it needs too, so I'm excited for them to arrive.

I took a bunch of pictures, I may make a new thread and post them, or put them in this one, with Gary's blessing since I'm really just following his plans.
 
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