If you want to skip all the technical mumbo jumbo skip down til the line "Now for the fun part, the assembly pictures!". However, if you are at all interested in a very quick(in my view) overview of the process of designing my speakers...please read on.
Well this thread has technically been 4 years in the making. My roommate sophomore year in college was into building his own speakers. He introduced me to the idea and I took it and ran with it from there. You'll find there are typically two types of speaker builders, those that will build the kits/other people's designs/go by the "typical" design and those that create a custom build. My roommate was the former...I discovered I was the latter.
Being an EE, It was one of the first things that really made me love my classroom material. I spent the first year or so just reading up information. There are numerous books available to those who really want the science of speaker building. My first was "The Loudspeaker Cookbook". I would recommend this to anyone who really is truly interested in most ALL the various effects that go into speaker design. It gets fairly technical and uses lots of measurements to present the material discussed. Another good resource is message boards. There are message boards that tend to cater to different levels of detail. Here are a few of the ones I used:
Parts Express Forums - Tends to be less technical
HT Guide - Can get VERY technical.
Madisound Forums - Mixed crowd...some more technical, some not
There are others but I found HT Guide to be the most helpful once I got deeply involved in speaker design.
When I began looking into building my actual first design, many strongly encouraged I take up a "proven" design. I resisted this mainly due to the nature of my major. I figured I would learn more, even with failure, over time if it was truly my own design. With much deliberation I decided to design a speaker based on the Hivi M6a and the Seas 27TDFC/TV.
Hi-Vi is better known as the Swan Speaker company. The M6a is used in many of their speaker designs. Seas is a well known speaker company mainly for their tweeters. However, they also have very high end lines of woofers.
Speaker building resources are sometimes scarce. For parts here are a few places where individual drivers, circuitry and other components can be purchased:
Madisound
Zalytron
Parts Express
Speaker City
I purchased components from Madisound and Parts Express. Both which had very good service and I would recommend each for anyone looking to purchase components.
Now, I won't go into all the steps I went through in the process of learning and designing this speaker as I could probably write a book on that. However, I should note that I quickly learned that there is ALWAYS more you can learn. Once you think you have everything figured out, there is always another hurdle to get over. I found this to be part of the fun, especially once you eventually solved the problem.
If you are serious about designing your own speakers, you should get accustomed to design software. I used Speaker Workshop throughout my entire project. It is freeware, but unfortunately has stopped being developed. There are some "interesting" aspects of the software but nothing a little experimentation can't get over.
The first major step of any speaker design is to measure the impedance of the speaker in "free-air". For this measurement, the driver(individual woofer or tweeter) is typically mounted horizontally but without an enclosure. By connecting the driver to a circuit and then to your sound card, you can measure the impedance curve.
M6a Impedance Curve
27TDFC Impedance Curve
I spent quite a long time getting the measurement to look this nice. I invested in a E-mu 1212m sound card and built the circuit as specified in Speaker Workshop with strong connections and good components.
As you can see from the impedance curve, all drivers have a resonance(the spike on the left of the graph) and a rising impedance as frequency increases. These impedance curves are used to calculate the T/S parameters which will later be used to design the enclosure and the crossover.
At this point, I designed the first component of my crossover circuit, the Zobel networks. These circuits remove the rising impedance and/or the resonances from the impedance curves. This proves important because in a passive crossover which most speakers use, the crossover point depends greatly on the impedance of the driver it is connected to. If the impedance changes, so does the crossover point. Once I added these circuits, I remeasured the impedance and obtained these new graphs:
Hivi M6a w/ Zobel
Seas 27TDFC/TV w/ Zobel
As you can see, the circuits that were added removed the resonance from the tweeter and the rising impedance from the woofer. Now we're getting somewhere!
Skipping ahead, after calculating the T/S parameters via the collected data, I went ahead and purchased the enclosures for my speakers. I decided to purchase premade enclosures(I know...booo hissss) because, for the price, they are well built and would be difficult to beat without some very good tools and woodworking skills.
Cabinets at Partsexpress
Cabinet in real life #1
Of course they came with a front to them...I just don't have a picture of that quite yet
So after receiving these it was now possible to test the speakers acoustically. I had bought a Behringer ECM8000 omnidirectional microphone and a Xenyx 802 mixer to power the microphone for these measurements. Here are the initial acoustic measurements of the drivers:
Hivi M6a Frequency Response
Seas 27TDFC/TV Frequency Response
These measurements are VERY important as they model the frequency curves that will be used to design the final crossover. Because these measurements were taken with the driver mounted to the front of the cabinets, we know that these measurements have all the effects the shape of our speaker will apply. I could tell this was going to be a challenge! These graphs don't look "flat" at all!
Again, I could go into much greater detail, but the final crossover design was a modified Linkwitz-riley 2nd order high pass on the tweeter and a 4th order low pass on the woofer. Speaker workshop can take this acoustic and impedance data that was measured and simulate the final combined frequency response of the entire speaker. This is VERY nice tool to have as it takes SOME of the guesswork out of designing a speaker.
Predicted Frequency Response of final speaker
Hey! That's not looking half bad!
Since this was going to be a ported design it was important to pick the appropriate size and length of port. This can be done via the T/S parameters we measured earlier and taking into consideration the acoustic response of the speaker. I decided to place a 2" diameter by 2" long flared port onto the front of the speaker. The original design was to place it on the back as is typical. However, due to the curved cabinets, the port would not fit on the small back.
Now for the fun part, the assembly pictures!
Cutout front baffle with slight oops on the bottom
Testing to verify that the components fit into the flush mounted cuts - Tape is to protect the surface
Back of the front baffle - Good shot of the port here
Cabinets w/ damping material and terminal block - has damping material and terminal block added.
Woofer Crossover(left) and Tweeter Crossover(right)
All four crossovers Two for each speaker
Woofer Crossover wired up
Baffle Step Compensation circuitry - Due to the size of this inductor, this was mounted separately. The large inductor was necessary to attenuate at pretty low frequencies. Basically, speakers naturally play higher frequencies louder because they "bounce" off the front of the speaker whereas low frequencies "wrap" around the speaker.
The crossovers are mounted in the enclosure - Rather tight fit. Probably should have compacted the circuits a bit more. However, space between inductors is always a good thing.
All the wiring connected along with the drivers themselves
Final Result!
Final Result Angle Shot
Final Result w/ Grill
I am quite happy with how they turned out aesthetically. My gf was even liking them so they pass at least her discerning eye!
So....how do they sound? How close do they come to the predicted result? You be the judge:
Measured Frequency Response
They measured to about 48-20KHz +/- 3dB. The attenuation on the very upper end is simply a limitation of the Behringer ECM8000 microphone. I was very pleased with these results. The speaker sounds a little bit on the brighter end and is crystal clear. I've listened to a few different genres of music with this so far and it does all types well, however I think it does the best with more vocal-esque tracks. Voices really come through clearly and aren't muffled whatsoever.
That's about all I got from here. Mission accomplished. I've heard people stating on these forums that they have "no idea why speaker companies can get away with charging what they do for speakers that are simple to make". Let me tell you, they are NOT simple to make. Nor are they cheap. Each of these speakers parts alone costs approx $300($600 per pair) and that doesn't include the investments I made into measurement equipment. However, I would say these will best any $300 speaker out there. These beasts weigh quite a lot too. I would say somewhere in the 40lb range per speaker!
Comments/questions are welcome.
Well this thread has technically been 4 years in the making. My roommate sophomore year in college was into building his own speakers. He introduced me to the idea and I took it and ran with it from there. You'll find there are typically two types of speaker builders, those that will build the kits/other people's designs/go by the "typical" design and those that create a custom build. My roommate was the former...I discovered I was the latter.
Being an EE, It was one of the first things that really made me love my classroom material. I spent the first year or so just reading up information. There are numerous books available to those who really want the science of speaker building. My first was "The Loudspeaker Cookbook". I would recommend this to anyone who really is truly interested in most ALL the various effects that go into speaker design. It gets fairly technical and uses lots of measurements to present the material discussed. Another good resource is message boards. There are message boards that tend to cater to different levels of detail. Here are a few of the ones I used:
Parts Express Forums - Tends to be less technical
HT Guide - Can get VERY technical.
Madisound Forums - Mixed crowd...some more technical, some not
There are others but I found HT Guide to be the most helpful once I got deeply involved in speaker design.
When I began looking into building my actual first design, many strongly encouraged I take up a "proven" design. I resisted this mainly due to the nature of my major. I figured I would learn more, even with failure, over time if it was truly my own design. With much deliberation I decided to design a speaker based on the Hivi M6a and the Seas 27TDFC/TV.
Hi-Vi is better known as the Swan Speaker company. The M6a is used in many of their speaker designs. Seas is a well known speaker company mainly for their tweeters. However, they also have very high end lines of woofers.
Speaker building resources are sometimes scarce. For parts here are a few places where individual drivers, circuitry and other components can be purchased:
Madisound
Zalytron
Parts Express
Speaker City
I purchased components from Madisound and Parts Express. Both which had very good service and I would recommend each for anyone looking to purchase components.
Now, I won't go into all the steps I went through in the process of learning and designing this speaker as I could probably write a book on that. However, I should note that I quickly learned that there is ALWAYS more you can learn. Once you think you have everything figured out, there is always another hurdle to get over. I found this to be part of the fun, especially once you eventually solved the problem.
If you are serious about designing your own speakers, you should get accustomed to design software. I used Speaker Workshop throughout my entire project. It is freeware, but unfortunately has stopped being developed. There are some "interesting" aspects of the software but nothing a little experimentation can't get over.
The first major step of any speaker design is to measure the impedance of the speaker in "free-air". For this measurement, the driver(individual woofer or tweeter) is typically mounted horizontally but without an enclosure. By connecting the driver to a circuit and then to your sound card, you can measure the impedance curve.
M6a Impedance Curve
27TDFC Impedance Curve
I spent quite a long time getting the measurement to look this nice. I invested in a E-mu 1212m sound card and built the circuit as specified in Speaker Workshop with strong connections and good components.
As you can see from the impedance curve, all drivers have a resonance(the spike on the left of the graph) and a rising impedance as frequency increases. These impedance curves are used to calculate the T/S parameters which will later be used to design the enclosure and the crossover.
At this point, I designed the first component of my crossover circuit, the Zobel networks. These circuits remove the rising impedance and/or the resonances from the impedance curves. This proves important because in a passive crossover which most speakers use, the crossover point depends greatly on the impedance of the driver it is connected to. If the impedance changes, so does the crossover point. Once I added these circuits, I remeasured the impedance and obtained these new graphs:
Hivi M6a w/ Zobel
Seas 27TDFC/TV w/ Zobel
As you can see, the circuits that were added removed the resonance from the tweeter and the rising impedance from the woofer. Now we're getting somewhere!
Skipping ahead, after calculating the T/S parameters via the collected data, I went ahead and purchased the enclosures for my speakers. I decided to purchase premade enclosures(I know...booo hissss) because, for the price, they are well built and would be difficult to beat without some very good tools and woodworking skills.
Cabinets at Partsexpress
Cabinet in real life #1
Of course they came with a front to them...I just don't have a picture of that quite yet
So after receiving these it was now possible to test the speakers acoustically. I had bought a Behringer ECM8000 omnidirectional microphone and a Xenyx 802 mixer to power the microphone for these measurements. Here are the initial acoustic measurements of the drivers:
Hivi M6a Frequency Response
Seas 27TDFC/TV Frequency Response
These measurements are VERY important as they model the frequency curves that will be used to design the final crossover. Because these measurements were taken with the driver mounted to the front of the cabinets, we know that these measurements have all the effects the shape of our speaker will apply. I could tell this was going to be a challenge! These graphs don't look "flat" at all!
Again, I could go into much greater detail, but the final crossover design was a modified Linkwitz-riley 2nd order high pass on the tweeter and a 4th order low pass on the woofer. Speaker workshop can take this acoustic and impedance data that was measured and simulate the final combined frequency response of the entire speaker. This is VERY nice tool to have as it takes SOME of the guesswork out of designing a speaker.
Predicted Frequency Response of final speaker
Hey! That's not looking half bad!
Since this was going to be a ported design it was important to pick the appropriate size and length of port. This can be done via the T/S parameters we measured earlier and taking into consideration the acoustic response of the speaker. I decided to place a 2" diameter by 2" long flared port onto the front of the speaker. The original design was to place it on the back as is typical. However, due to the curved cabinets, the port would not fit on the small back.
Now for the fun part, the assembly pictures!
Cutout front baffle with slight oops on the bottom
Testing to verify that the components fit into the flush mounted cuts - Tape is to protect the surface
Back of the front baffle - Good shot of the port here
Cabinets w/ damping material and terminal block - has damping material and terminal block added.
Woofer Crossover(left) and Tweeter Crossover(right)
All four crossovers Two for each speaker
Woofer Crossover wired up
Baffle Step Compensation circuitry - Due to the size of this inductor, this was mounted separately. The large inductor was necessary to attenuate at pretty low frequencies. Basically, speakers naturally play higher frequencies louder because they "bounce" off the front of the speaker whereas low frequencies "wrap" around the speaker.
The crossovers are mounted in the enclosure - Rather tight fit. Probably should have compacted the circuits a bit more. However, space between inductors is always a good thing.
All the wiring connected along with the drivers themselves
Final Result!
Final Result Angle Shot
Final Result w/ Grill
I am quite happy with how they turned out aesthetically. My gf was even liking them so they pass at least her discerning eye!
So....how do they sound? How close do they come to the predicted result? You be the judge:
Measured Frequency Response
They measured to about 48-20KHz +/- 3dB. The attenuation on the very upper end is simply a limitation of the Behringer ECM8000 microphone. I was very pleased with these results. The speaker sounds a little bit on the brighter end and is crystal clear. I've listened to a few different genres of music with this so far and it does all types well, however I think it does the best with more vocal-esque tracks. Voices really come through clearly and aren't muffled whatsoever.
That's about all I got from here. Mission accomplished. I've heard people stating on these forums that they have "no idea why speaker companies can get away with charging what they do for speakers that are simple to make". Let me tell you, they are NOT simple to make. Nor are they cheap. Each of these speakers parts alone costs approx $300($600 per pair) and that doesn't include the investments I made into measurement equipment. However, I would say these will best any $300 speaker out there. These beasts weigh quite a lot too. I would say somewhere in the 40lb range per speaker!
Comments/questions are welcome.
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