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This is the first project I've posted, so here goes 
A friend of mine that I work with was chatting with me and said he was searching Craigslist for a pair of speakers for his garage, looking to spend around $50 / pair. I saw this as a perfect opportunity for a project. He agreed to let me build him something as opposed to buying something worn out, made of half inch chip board, and possibly stolen..
I knew he liked heavier music like Metallica, Tesla, etc. and that he is a huge fan of the sound of the big floor speakers of days past, so I tried to recreate that style speaker, but better than most cheapos, in a smaller form to work in the garage.
Drivers:
I opted for an 8" woofer and a tweeter. I figured that this gave me the most woofer I could find to work in a two-way with a super inexpensive crossover option, as well as work well for his music choice.
I chose the MCM 55-2971 (sorry PE, just couldn't argue with a $7.50 woofer for this project..) 8" poly cone woofer. For the price, the specs are very good, although being realistic, I don't believe for a minute that the specs are completely accurate..
I wanted a paper cone tweeter because I wanted that vintage sound, and for the price I didn't have much for options. I didn't want a piezo and don't much care for the "ticky" sound of mylar semidomes. I saw the Goldwood GT25 and was satisfied with how it would likely work for this project and it had a respectable power handling. In PCD, I was able to make it blend with the MCM 8 relatively well with just a cap.
Crossover:
To keep budget, any inductors were out. I used PCD7 and was able to allow the woofer to roll off naturally and get by with a first order on the tweeter. I used a 3.3uf poly cap. This made for a higher crossover point than typically desirable, but figured it was worth a shot, and worked out well. I physically aligned the coils, so driver alignment was factored, and the tweeter was wired in positive polarity.
Cabinet:
Menards has some sanded finished pine plywood that has been looking interesting to me to work with, was relatively cheap when on sale, and was very easy to work with. I used 3/4" throughout. It wasn't entirely void free, but wasn't bad at all. The volume ended up being about 1.1 ft3 gross, tuned to 41 hz. This project was an opportunity where "acoustic ratio" proportions would work, so I used them in the design. The cabinet is air nailed, glued, braced, and caulked. It doesn't ring at all and is solid and dead. The port is a slot style on the front bottom. The upper portion is stuffed. I had stuffing throughout, but sounded better with an empty chamber behind the woofer.
I wanted to align the driver coils, so I fabricated a wave guide, which was a ton of work, but turned out well. The cabinet was stained, but the guide was sprayed with Rustoleum bedliner, which gives a horn look and texture.
I covered the drivers with grilles I made using cloth and soft copper tube made into a ring. He wanted grilles, so I made a set from cloth and 1/4 inch hardboard.
Listening:
All in all, they sound very good. They have a very spacious sound that isn't localized and stages very well. The bass is solid and not boomy at all. My only complaint is that the midrange lacks attack and seems to be a little soft. I attempted reversing tweeter polarity and that was not good at all. I'm certain that a more proper crossover could remedy this if budget allowed. The tweeter initially had a bright laserbeam hotspot, but behind the ring grille over it, i affixed a small cotton ball in the center, in front of the dustcap, which resolved that quite nicely. The whole system sounded worlds better after about 24 hours of break-in.
My final thoughts:
They sound much better than they have any right to for the price. Underestimating lumber, shipping, and not initially pricing in grilles, I was slightly over budget, but still not far off. They are fun and pleasant to listen to, and frankly I don't really want to part with them after listening to them for 3 days. I bring them to the guy today for his first look and listen, wish me luck! :D
A friend of mine that I work with was chatting with me and said he was searching Craigslist for a pair of speakers for his garage, looking to spend around $50 / pair. I saw this as a perfect opportunity for a project. He agreed to let me build him something as opposed to buying something worn out, made of half inch chip board, and possibly stolen..
I knew he liked heavier music like Metallica, Tesla, etc. and that he is a huge fan of the sound of the big floor speakers of days past, so I tried to recreate that style speaker, but better than most cheapos, in a smaller form to work in the garage.
Drivers:
I opted for an 8" woofer and a tweeter. I figured that this gave me the most woofer I could find to work in a two-way with a super inexpensive crossover option, as well as work well for his music choice.
I chose the MCM 55-2971 (sorry PE, just couldn't argue with a $7.50 woofer for this project..) 8" poly cone woofer. For the price, the specs are very good, although being realistic, I don't believe for a minute that the specs are completely accurate..
I wanted a paper cone tweeter because I wanted that vintage sound, and for the price I didn't have much for options. I didn't want a piezo and don't much care for the "ticky" sound of mylar semidomes. I saw the Goldwood GT25 and was satisfied with how it would likely work for this project and it had a respectable power handling. In PCD, I was able to make it blend with the MCM 8 relatively well with just a cap.
Crossover:
To keep budget, any inductors were out. I used PCD7 and was able to allow the woofer to roll off naturally and get by with a first order on the tweeter. I used a 3.3uf poly cap. This made for a higher crossover point than typically desirable, but figured it was worth a shot, and worked out well. I physically aligned the coils, so driver alignment was factored, and the tweeter was wired in positive polarity.
Cabinet:
Menards has some sanded finished pine plywood that has been looking interesting to me to work with, was relatively cheap when on sale, and was very easy to work with. I used 3/4" throughout. It wasn't entirely void free, but wasn't bad at all. The volume ended up being about 1.1 ft3 gross, tuned to 41 hz. This project was an opportunity where "acoustic ratio" proportions would work, so I used them in the design. The cabinet is air nailed, glued, braced, and caulked. It doesn't ring at all and is solid and dead. The port is a slot style on the front bottom. The upper portion is stuffed. I had stuffing throughout, but sounded better with an empty chamber behind the woofer.
I wanted to align the driver coils, so I fabricated a wave guide, which was a ton of work, but turned out well. The cabinet was stained, but the guide was sprayed with Rustoleum bedliner, which gives a horn look and texture.
I covered the drivers with grilles I made using cloth and soft copper tube made into a ring. He wanted grilles, so I made a set from cloth and 1/4 inch hardboard.
Listening:
All in all, they sound very good. They have a very spacious sound that isn't localized and stages very well. The bass is solid and not boomy at all. My only complaint is that the midrange lacks attack and seems to be a little soft. I attempted reversing tweeter polarity and that was not good at all. I'm certain that a more proper crossover could remedy this if budget allowed. The tweeter initially had a bright laserbeam hotspot, but behind the ring grille over it, i affixed a small cotton ball in the center, in front of the dustcap, which resolved that quite nicely. The whole system sounded worlds better after about 24 hours of break-in.
My final thoughts:
They sound much better than they have any right to for the price. Underestimating lumber, shipping, and not initially pricing in grilles, I was slightly over budget, but still not far off. They are fun and pleasant to listen to, and frankly I don't really want to part with them after listening to them for 3 days. I bring them to the guy today for his first look and listen, wish me luck! :D
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