Hi Everyone! I'm new here. this is my first post here but I've been active on audiokarma for years which is a hifi audio forum. My name is nick and im a 25 year old broke college student and I'm getting my degree in mechanical engineering and I do audio engineering as a hobby. given the fact that I have to work so much to pay for things nowadays, I spend a lot of time driving so naturally my hi-fi audio hobby wants to intrude. I've done lots of car systems for friends, and have built and engineered tons of subwoofers and main speakers for hi-fi. I used to have a cnc machine in my closet (i have a giant 7'x7' closet) but had to sell it since my gf lives in Germany and i had to pay for a vacation to Italy. now I have a 3d printer and I wanted to share a project I did. I had time to engineer and develop some dashboard mountable car audio speaker pods and I am blown away by the results. Because they are pointed right at you and cover most of the frequency range, the benifits in sound quality are immense.
The plan
My plan was to build A two way with a 3" faitalPRO 3FE22 woofer and a Dayton AMT ribbon tweeter with a second order crossover for each crammed in the back. It covers 400hz to 20,000Hz, and is designed to be paired with a midbass driver. I started about 5 months ago, and have been prototyping enclosure designs and simulating the design in xsim and I went through about 4 different tweeters that while simulating and measuring good in the impendence, time, and phase domain, just didn't sound good. I finally arrived at the Dayton audio AMTPOD-4. a little AMT speaker pod. because an amt tweeter does not have a "voice coil" per se, it is a horizontal zig zag pattern of wire, there are no inductive properties of an amt design, so it has a flat impendence and phase curve, and hardly has any reactance with the inductor and capacitor resulting in a super flat accurate treble. every spatial detail is reproduced perfectly
The engineering (might be a dry read for some people)
Here is the final result. Each enclosure is 3D printed from ASA, a weatherproof and UV-proof material. The enclosure is printed as two pieces, a back plate, and the main enclosure. The main enclosure takes 20 hours to 3-d Print and is very difficult to get right since the first few layers always like to peel up due to ASA having a high thermal expansion coefficient. The back plate has features for countersinking the crossover inductors and capacitors as well. careful attention has been given to the placement and position of the inductors. They are below the tweeter, as far away from the woofer magnet as possible, and they are oriented 90 degrees from each other. I actually wired them up and ran some frequency sweeps with my Dayton audio test system and found an orientation for the inductors that minimized the interaction between the inductors and the woofer magnet since they are in such close proximity. There actually was an appreciable difference in both the inductor value and the impendence curve with different orientations of the inductors, all of which have been factored into my simulations. The crossovers take a good amount of time to wire up, which includes soldering and heat shrinking every connection. After simulating the design with X-sim, I arrived at a good compromise in the phase domain and capacitor values, while ensuring each driver is rolling off nicely. The simulations show +/- 15 degrees of phase delay from 500hz to 20Khz which is great, however the actual design, blows this out of the water with only +/- 6.5 degrees of phase delay (measured) from 500hz to 20Khz. They also don't need a high pass filter on the 3" woofer, as it naturally tapers off below 1000Hz and with my car head unit, I can add a high pass filter around 200hz to further reduce the low end. The enclosure is 7 mm thick solid plastic and has some large internal ribbing and supports to stiffen up the sidewalls to reduce resonances. The enclosure weighs 250 Grams on its own so somewhat hefty. I also used a little bit of fiberglass in the enclosure to further deaden the sound. these are slightly rough prototypes. the final ones will have sharper crisper edges as i sanded these down a bit too much.
The Sound (what you came for)
With my head unit dsp time alignment properly adjusted, they sound stunning. They sound super flat and accurate and I am elated with these. There is an enormous contrast between different recordings. Led Zepplins Fool in the rain sound very dry (As it should), and more modern recordings from "Bill Eye-lash" like are super crisp and clear, and every instrument has a place in front of me. They are hardly ever overly shouty, and the treble is very non fatiguing and soft but exceptionally clear. because these 3" faitals are playing the entire human vocal range unimpeded, the vocals are incredibly clear and lifelike and sound like they are directly in front of you at all frequencies. If you cross a tweeter over too low, you'll have the human voice being split between two speakers, a woofer and a tweeter. It is much harder to convince your brain that the sound is coming from one source when it is being split between two drivers so this is a critical aspect of the design. I also listened to "your blue room" from the passengers original soundtracks (with U2). This is a superb quality cinema soundtrack and it just floors me with incredible sound from these speakers. super crisp clear treble and the keyboard sounds on the track are very mid-rangey and can be harsh if your speakers aren't good in that area, but these sound absolutely perfect and I am just enveloped by incredible sound. Listening to Beck's "the golden age". His vocals are super tight and "in front of me" and the echo/ambiance that his vocal track has in this recording is reproduced perfectly in the space in front of me. Every bell and chime in the right channel in this song sounds very natural, present, and precise. I am also using a FaitalPRO 6FE200 6" woofer for the midwoofer, and a 10" ciare HS251 DVC subwoofer that I designed.
I am absolutely floored with these. they have far surpassed my expectations and I look forward to every drive to and from my amazon job a lot more. I have listened to a lot of good hi-fi and car systems and have a pretty fantastic system of my own, but these far surpassed my expectations. If it weren't for the lower end kenwood head unit, I wound say these are very close to studio quality sound in your car. the treble is clear because they have been well designed, not because they have boosted treble. boosting the treble creates a sort of artificial clarity so lots of crappy audio manufacturers do this. these speakers have hardly any phase problems and because of this, as you move around the speaker (off axis), the tonality remains very consistent and even in the passenger seat the tonality is still super accurate and it sounds great, and the speakers are very clear, despite the fact that the time alignment is not tuned for the passenger. Anywho, i hope you found this interesting and maybe learned something.
If anyone is interested in these id love to make more!
thanks for reading!
-Nick
also here is a photo of the measured phase delay and impendence curve. Impendence does not dip below 4 ohms which is great for your amplifier and is mostly flat, staying below 8 ohms down to 200hz
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The plan
My plan was to build A two way with a 3" faitalPRO 3FE22 woofer and a Dayton AMT ribbon tweeter with a second order crossover for each crammed in the back. It covers 400hz to 20,000Hz, and is designed to be paired with a midbass driver. I started about 5 months ago, and have been prototyping enclosure designs and simulating the design in xsim and I went through about 4 different tweeters that while simulating and measuring good in the impendence, time, and phase domain, just didn't sound good. I finally arrived at the Dayton audio AMTPOD-4. a little AMT speaker pod. because an amt tweeter does not have a "voice coil" per se, it is a horizontal zig zag pattern of wire, there are no inductive properties of an amt design, so it has a flat impendence and phase curve, and hardly has any reactance with the inductor and capacitor resulting in a super flat accurate treble. every spatial detail is reproduced perfectly
The engineering (might be a dry read for some people)
Here is the final result. Each enclosure is 3D printed from ASA, a weatherproof and UV-proof material. The enclosure is printed as two pieces, a back plate, and the main enclosure. The main enclosure takes 20 hours to 3-d Print and is very difficult to get right since the first few layers always like to peel up due to ASA having a high thermal expansion coefficient. The back plate has features for countersinking the crossover inductors and capacitors as well. careful attention has been given to the placement and position of the inductors. They are below the tweeter, as far away from the woofer magnet as possible, and they are oriented 90 degrees from each other. I actually wired them up and ran some frequency sweeps with my Dayton audio test system and found an orientation for the inductors that minimized the interaction between the inductors and the woofer magnet since they are in such close proximity. There actually was an appreciable difference in both the inductor value and the impendence curve with different orientations of the inductors, all of which have been factored into my simulations. The crossovers take a good amount of time to wire up, which includes soldering and heat shrinking every connection. After simulating the design with X-sim, I arrived at a good compromise in the phase domain and capacitor values, while ensuring each driver is rolling off nicely. The simulations show +/- 15 degrees of phase delay from 500hz to 20Khz which is great, however the actual design, blows this out of the water with only +/- 6.5 degrees of phase delay (measured) from 500hz to 20Khz. They also don't need a high pass filter on the 3" woofer, as it naturally tapers off below 1000Hz and with my car head unit, I can add a high pass filter around 200hz to further reduce the low end. The enclosure is 7 mm thick solid plastic and has some large internal ribbing and supports to stiffen up the sidewalls to reduce resonances. The enclosure weighs 250 Grams on its own so somewhat hefty. I also used a little bit of fiberglass in the enclosure to further deaden the sound. these are slightly rough prototypes. the final ones will have sharper crisper edges as i sanded these down a bit too much.
The Sound (what you came for)
With my head unit dsp time alignment properly adjusted, they sound stunning. They sound super flat and accurate and I am elated with these. There is an enormous contrast between different recordings. Led Zepplins Fool in the rain sound very dry (As it should), and more modern recordings from "Bill Eye-lash" like are super crisp and clear, and every instrument has a place in front of me. They are hardly ever overly shouty, and the treble is very non fatiguing and soft but exceptionally clear. because these 3" faitals are playing the entire human vocal range unimpeded, the vocals are incredibly clear and lifelike and sound like they are directly in front of you at all frequencies. If you cross a tweeter over too low, you'll have the human voice being split between two speakers, a woofer and a tweeter. It is much harder to convince your brain that the sound is coming from one source when it is being split between two drivers so this is a critical aspect of the design. I also listened to "your blue room" from the passengers original soundtracks (with U2). This is a superb quality cinema soundtrack and it just floors me with incredible sound from these speakers. super crisp clear treble and the keyboard sounds on the track are very mid-rangey and can be harsh if your speakers aren't good in that area, but these sound absolutely perfect and I am just enveloped by incredible sound. Listening to Beck's "the golden age". His vocals are super tight and "in front of me" and the echo/ambiance that his vocal track has in this recording is reproduced perfectly in the space in front of me. Every bell and chime in the right channel in this song sounds very natural, present, and precise. I am also using a FaitalPRO 6FE200 6" woofer for the midwoofer, and a 10" ciare HS251 DVC subwoofer that I designed.
I am absolutely floored with these. they have far surpassed my expectations and I look forward to every drive to and from my amazon job a lot more. I have listened to a lot of good hi-fi and car systems and have a pretty fantastic system of my own, but these far surpassed my expectations. If it weren't for the lower end kenwood head unit, I wound say these are very close to studio quality sound in your car. the treble is clear because they have been well designed, not because they have boosted treble. boosting the treble creates a sort of artificial clarity so lots of crappy audio manufacturers do this. these speakers have hardly any phase problems and because of this, as you move around the speaker (off axis), the tonality remains very consistent and even in the passenger seat the tonality is still super accurate and it sounds great, and the speakers are very clear, despite the fact that the time alignment is not tuned for the passenger. Anywho, i hope you found this interesting and maybe learned something.
If anyone is interested in these id love to make more!
thanks for reading!
-Nick
also here is a photo of the measured phase delay and impendence curve. Impendence does not dip below 4 ohms which is great for your amplifier and is mostly flat, staying below 8 ohms down to 200hz
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