If you would like to understand the title, please Google "the infinite monkey theorem"
This will be the start of my build log. A little background on this: For the past year I have been pouring through everything from white papers to text books, and sending out emails all over the place to learn about audio and speaker design. I've gone down so many rabbit holes. There is so much to learn and so many details you can expand upon in design. There's also something called the law of diminishing returns. At this point, I just wanna make something. So here we go:
T he objective is a set of active monitors with the best distortion figures possible while still being somewhat compact (and before you say it i am WELL aware of how many other designs there are out there). Some components will be expensive, others will not. Trying to be at least somewhat cost effective... I'm not the monopoly guy.
Here's the concept:
(I apologize for the chicken scratch, but I'm currently on vacation and decided to sketch it out a little with a notepad on hand)
Starting with the body: I found a little while ago a company that makes prefabricated carbon fiber parts. In this instance, a carbon fiber tube ( https://dragonplate.com/1075-id-x-48-carbon-fiber-tube ). Split that in half, and possibly a little more, and you have yourself a very rigid skin. It will be attached to a base (most likely MDF) and have a small bracket in the center (more on that later). Next would come a CLD layer, then the rest of the contents of the speaker.
The inside will be in 4 pieces. Each will contain a driver except for the one with the electronics. The 2 pieces on the sides will each contain a seas 8" sub. The placement will allow for force cancelation of each woofer allowing it to hit lower frequencies as well as cancel out any modes not supposed to be there. Additionally, because sound becomes omnidirectional at lower frequencies, and because it's a round enclosure, I shouldn't have to worry too much about distorting modes caused by edges and baffle stepping.
At the front will be an MTM configuration for the rest of the frequencies. This will be a small enclosure that has its own sound dampening seperately from the main chamber. Originally I was thinking about bliesma M74 mids, bit it seems purifi still wins this round with lower distortion figures. Will be going with a set of 4" woofers. The trade off there is efficiency. The tweeter will be a RAAL 70-20.
The last piece will be the electronics enclosure. Going with a hypex fusion amp for this one. I would have loved to design the electronics as well, but I do not have access to a lab at the moment to test them so this is the next best thing lol. From there it's just a little more sound dampening, a cap on top, and voila.
With all that said, I still need to sift through all the particulars. Am definitely going to need to dust off my CAD skills to make sure everything fits together the way I think it will. May fiddle with the design a little more, but all in all, I think it'll turn out great! Would love to hear from those a little longer in the tooth who have more experience in this than I. This whole thing has been a learning experience, and we aren't done yet.
This will be the start of my build log. A little background on this: For the past year I have been pouring through everything from white papers to text books, and sending out emails all over the place to learn about audio and speaker design. I've gone down so many rabbit holes. There is so much to learn and so many details you can expand upon in design. There's also something called the law of diminishing returns. At this point, I just wanna make something. So here we go:
T he objective is a set of active monitors with the best distortion figures possible while still being somewhat compact (and before you say it i am WELL aware of how many other designs there are out there). Some components will be expensive, others will not. Trying to be at least somewhat cost effective... I'm not the monopoly guy.
Here's the concept:
(I apologize for the chicken scratch, but I'm currently on vacation and decided to sketch it out a little with a notepad on hand)
Starting with the body: I found a little while ago a company that makes prefabricated carbon fiber parts. In this instance, a carbon fiber tube ( https://dragonplate.com/1075-id-x-48-carbon-fiber-tube ). Split that in half, and possibly a little more, and you have yourself a very rigid skin. It will be attached to a base (most likely MDF) and have a small bracket in the center (more on that later). Next would come a CLD layer, then the rest of the contents of the speaker.
The inside will be in 4 pieces. Each will contain a driver except for the one with the electronics. The 2 pieces on the sides will each contain a seas 8" sub. The placement will allow for force cancelation of each woofer allowing it to hit lower frequencies as well as cancel out any modes not supposed to be there. Additionally, because sound becomes omnidirectional at lower frequencies, and because it's a round enclosure, I shouldn't have to worry too much about distorting modes caused by edges and baffle stepping.
At the front will be an MTM configuration for the rest of the frequencies. This will be a small enclosure that has its own sound dampening seperately from the main chamber. Originally I was thinking about bliesma M74 mids, bit it seems purifi still wins this round with lower distortion figures. Will be going with a set of 4" woofers. The trade off there is efficiency. The tweeter will be a RAAL 70-20.
The last piece will be the electronics enclosure. Going with a hypex fusion amp for this one. I would have loved to design the electronics as well, but I do not have access to a lab at the moment to test them so this is the next best thing lol. From there it's just a little more sound dampening, a cap on top, and voila.
With all that said, I still need to sift through all the particulars. Am definitely going to need to dust off my CAD skills to make sure everything fits together the way I think it will. May fiddle with the design a little more, but all in all, I think it'll turn out great! Would love to hear from those a little longer in the tooth who have more experience in this than I. This whole thing has been a learning experience, and we aren't done yet.
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Most likely. I was also considering going with the 503. The spec on the sub is 500W for one and the purifis can do 200w. That way I can use them for either near field or a larger room depending on volume needed. I know someone is going to comment "but it has a fan! blasphemous!" but whatever it has a DSP chill out lol
If you haven’t already,
Take a look at what Pat McGinty is doing with active speakers at Meadowlarksings.com
Take a look at what Pat McGinty is doing with active speakers at Meadowlarksings.com
"the infinite monkey theorem"
Yes, we know that.
I like another experiment: there are peanuts in a recipient where the aperture is as big as a hand. The monkey grabs as much peanuts as possible, but the hand holding all the peanuts won't pass through the aperture.
Me, I don't like electronics mixed with enclosures. I mean, you want super bass and build super soundproof boxes then you put delicate components inside.
I would not be surprised if after a year or so the thing breaks.
Same criteria applies to the speakers: why would you want the tweeter and midrange speakers sit in the same enclosure for the woofer?!
Yes, we know that.
I like another experiment: there are peanuts in a recipient where the aperture is as big as a hand. The monkey grabs as much peanuts as possible, but the hand holding all the peanuts won't pass through the aperture.
Me, I don't like electronics mixed with enclosures. I mean, you want super bass and build super soundproof boxes then you put delicate components inside.
I would not be surprised if after a year or so the thing breaks.
Same criteria applies to the speakers: why would you want the tweeter and midrange speakers sit in the same enclosure for the woofer?!
Why? You buying? 😛
I mean, there a lot of companies that do it and make very successful products. From a design perspective I'm not too crazy about it either, but a better solution is far more expensive and I also have an area constraint issue. Otherwise I would just make floor standing speakers.
For low end extension. A lot of cardioid designs do this in order to use the cardioid effect. Only difference there is instead of subwoofers they usually use multiple LF drivers to achieve the same bass response, or one similar enough to the other drivers to create the effect. The Kii 3 is a good example of this.
No, but I often get queried about what to buy in 'X' price range + I've learned the hard way about (some) folks that don't, so leery of any I'm not familiar with.
As a fellow new-to-this-field-but-learning kinda guy, best of luck! I hope you do well, please post updates here and your learnings if you can!
Will do! First thing I've learned is good parts are expensive 🙃
Actually something I'm looking into now is size and dimension. I may need to increase the diameter/circumference in order to accommodate the electronics. The whole idea is to have everything flush mount or just about. If I do that though, I will also need to look into if that would effect the force cancelation of the woofers and not make it work as intended.
Actually something I'm looking into now is size and dimension. I may need to increase the diameter/circumference in order to accommodate the electronics. The whole idea is to have everything flush mount or just about. If I do that though, I will also need to look into if that would effect the force cancelation of the woofers and not make it work as intended.
Just like any driver/box combo it's about having the right Vb/specs ratio for whatever desired response, so making it larger in diameter may require reducing internal net volume (Vb).
Oh that's not an issue. In fact, by design the layout has odd surfaces in the interior, so there's a lot of diffraction points inside the enclosure. It's that, at least from my understanding of the principle, force canceling requires the subs to be magnet to magnet in order for it to work. If that's not the case, and I can just mount them like any other speaker, then there's no problem.
What is force canceling?
The concept of force-cancelled drivers is simple; the same force applied to the cone; means the same force will be applied in the opposite direction – an equal and opposite force. Face two bass drivers in pairs and the reaction force of one will be the same as the other – equal and opposite.
The concept of force-cancelled drivers is simple; the same force applied to the cone; means the same force will be applied in the opposite direction – an equal and opposite force. Face two bass drivers in pairs and the reaction force of one will be the same as the other – equal and opposite.
Right! But I'm not sure how that effect will change moving the drivers farther apart. Will you still see the same radiation pattern spread further apart than directly back to back?
I guess that would be a good thing then since it's subwoofers. Would the radiation pattern change for the drivers at all? And would the gain still be the same? Given the increase in distance and the increase in enclosure volume, I imagine you would also have increased bass response.
Oh well, I re-read your intention and watched at the sketch. Now it's more clear.
It's all about implementation, I mean...the sketch looks like an assembled robot. If you can make a future -retro look like C1P8 -or it was c3p0- in Star Wars...Devialet style
Many compartments...
1 woofer brings trouble, 2 woofers=double.
One may say that the opposing forces in a simmetric cabinet might lead to minor vibration.
Now, make a solid cabinet (unobtanium material for making an inert enclosure for that space) and fill the gaps with MTM enclosure and amplifier.
Uhmmm... sorry, repetition of post #6
It's all about implementation, I mean...the sketch looks like an assembled robot. If you can make a future -retro look like C1P8 -or it was c3p0- in Star Wars...Devialet style
Many compartments...
1 woofer brings trouble, 2 woofers=double.
One may say that the opposing forces in a simmetric cabinet might lead to minor vibration.
Now, make a solid cabinet (unobtanium material for making an inert enclosure for that space) and fill the gaps with MTM enclosure and amplifier.
Uhmmm... sorry, repetition of post #6
"Subwoofers" covers an undefined frequency range, and you have not yet defined the cabinet volume or shape, so questions about radiation pattern change can't be answered.
That said, if the subwoofer driver's horizontal center to center distance around the cabinet perimeter is under around 2.8', their response will be within a few Hz around a 360 degree horizontal pattern.
Your imagination is correct, an increase in sealed enclosure volume will increase it's low frequency "gain", or sensitivity, though an increase in driver center to center distance will not.
Originally I wanted to do a cylinder. I figured that taking on a cylindrical shape would give me the most even dispersion pattern and would prevent baffle stepping. However, I'm starting to reconsider that. The hypex fusion amplifier is at a minimum ~5"x~12" (~6"x~16" if I go with more power). Keeping to the spirit of the design, if I went with a cylinder, it would be far larger than what I would be going for. The diameter cone to cone of the subs is ~10". I would have to add ~6" more if I wanted to accommodate the electronics while maintaining the same shape. That adds potentially a lot more size and a lot more mass and escapes being a bookshelf speaker. So I may have to go with a cuboid shape anyway out of pragmatism in order to cut down on size.
With all that said, after the conversation we had over on the other post ( https://www.diyaudio.com/community/threads/carbon-fiber.414830/#post-7730299 ) I'm also starting to reconsider what materials I would want to use for the enclosure. I'm still probably going to use the same CLD construction, but as far as material is concerned, anything epoxy, while having a low bar for entry, still takes experience that I do not have. Something I was considering is maybe getting it 3d printed and seeing if I can find a service that can print using higher quality materials than what I would be able to at home. I even put in an email to Alpine to see if they have anyone in their supply chain that can do one-offs of their HX5 material, but I won't hold my breath on that one.