Definitely the kind of product I'd like to approach with few differences though:
- not plastic for the reflector but wood for the inside + light insulation (I did a proto and sound leaks by the reflector itself)
- not micro directional speakers but traditional 7-9cm full range HP
- not suspended but based on the ground/office
Any direct radiator will beat hands down a reflector, do you remember the abandoned desings like the rabbits ears of Elipson : elipson oreille lapin – Recherche Google
Last edited:
If you decide you want to try some other build methods, I was originally thinking something along these lines. It's basically a flower petal design. Some guides to maintain curves could be used during glue-up. Alternatively, you could add some tabs that overlap adjacent petals (for rivets or screws if using sheet metal or plastic).
Making a Parabolic Reflector Out of a Flat Sheet
You should care at the thickness of your paper dome, one layer of 0.1mm is transparent to frequencies under 1KHz, if you expect to obtain some reverberation with a full range loudspeaker it must be very thick IMHO.
PS : the plan of mattstat link is a solar cooker.
Last edited:
I love your replies because they are constructive.
I indeed plan the flower method and you can see one of the petals on the picture I originally posted.
I intended to 3D print a guide for the parabolic part and then assemble within it the 2 wood layers (interior / exterior - 1mm), the 2 layers of liege (1mm) and the layer of wool (feutre).
I think I can hide most of the assembly tricks within the sandwich with wood & glue.
I may add thin metal pieces at the center of the flower (exterior) and at the edges to make it more robust.
I'm glad my comments have been helpful. Sorry I didn't understand some of the details in the drawing.
On the sandwich construction details, you may want to do some small prototype sections to test the efficiency of the stack before you build a full unit. You may be able to omit some layers, or find that a different combination is more effective. The cork layer in particular seems like it may not add much. A sheet damping material may be more effective, but would add weight.
To test small sections, you could put an exciter on the inside of the test panel and measure the sound pressure level on the outside panel. If you keep the microphone very close to the outside panel that should minimize interference from the inside panel's sound. For the cleanest measurements you'd want a box sealing to the perimeter of the inside panel and isolating that side from the measurement side.
Dayton Audio DAEX25VT-4 Vented 25mm Exciter 20W 4 Ohm
On the sandwich construction details, you may want to do some small prototype sections to test the efficiency of the stack before you build a full unit. You may be able to omit some layers, or find that a different combination is more effective. The cork layer in particular seems like it may not add much. A sheet damping material may be more effective, but would add weight.
To test small sections, you could put an exciter on the inside of the test panel and measure the sound pressure level on the outside panel. If you keep the microphone very close to the outside panel that should minimize interference from the inside panel's sound. For the cleanest measurements you'd want a box sealing to the perimeter of the inside panel and isolating that side from the measurement side.
Dayton Audio DAEX25VT-4 Vented 25mm Exciter 20W 4 Ohm
No, this is new for me, very interesting, thank you!
I have seen Elipson old models like this:
but never the "rabbit ears"
Attachments
Neither IRL, they are "fun looking" bad sounding devices inspired by the disruptive hype of the "la nouvelle vague" era in France.No, this is new for me, very interesting, thank you!
I have seen Elipson old models like this:
but never the "rabbit ears"
Thanks for the idea of the damping sheet, that was my initial choice as well but then I tried to figure out "natural" materials so that the concept is as "natural"as possible (form, materials, speaker => sound) thus the cork. I tried to stick to mass/air/mass concept for insulation thus the sandwich with the wool (I agree cork is not so massive but it has good properties).
What affordable option do you recommend to measure SPL correctly?
If you can deal with the complexity, you could try sand between your layers of wood for damping. It's pretty massive and natural. Loose sand would probably be best, but if you can find a flexible glue to suspend it in, that could work too.
On measuring: it depends on what you are trying to measure. If you just want a basic, broadband sound pressure level reading, many people use phone apps for that now, since they typically have the phone already and they're reasonably accurate.
Here's a review of some apps and their accuracy.
So How Accurate Are These Smartphone Sound Measurement Apps? | | Blogs | CDC
Last time I looked, SPL Pro by Studio Six Digital seemed like one of the better ones. They also have other modules to do RTA and FFT, but I don't have experience with those.
If you want an external mic, something like this usually works well
Dayton Audio iMM-6 Calibrated Measurement Microphone for Tablets iPhone iPad and Android
I have an older Audiomatica CLIO Lite system for measurements, but I wouldn't put that in the "affordable" range for someone that's not going to do a lot of measuring. For what it does, it's affordable, but that's likely more than you'll need. The current equivalent is the CLIO Pocket.
Audiomatica CLIO Pocket Version 2 Personal Acoustic Measurement System
There are cheaper PC based options to do similar measurements, but I haven't used them. ARTA, REW, and HOLMImpulse are a few I've seen others mention.
On measuring: it depends on what you are trying to measure. If you just want a basic, broadband sound pressure level reading, many people use phone apps for that now, since they typically have the phone already and they're reasonably accurate.
Here's a review of some apps and their accuracy.
So How Accurate Are These Smartphone Sound Measurement Apps? | | Blogs | CDC
Last time I looked, SPL Pro by Studio Six Digital seemed like one of the better ones. They also have other modules to do RTA and FFT, but I don't have experience with those.
If you want an external mic, something like this usually works well
Dayton Audio iMM-6 Calibrated Measurement Microphone for Tablets iPhone iPad and Android
I have an older Audiomatica CLIO Lite system for measurements, but I wouldn't put that in the "affordable" range for someone that's not going to do a lot of measuring. For what it does, it's affordable, but that's likely more than you'll need. The current equivalent is the CLIO Pocket.
Audiomatica CLIO Pocket Version 2 Personal Acoustic Measurement System
There are cheaper PC based options to do similar measurements, but I haven't used them. ARTA, REW, and HOLMImpulse are a few I've seen others mention.
Thank you very much, I'll give a try to the android soft + microphone.
I'm not far from ordering the 3D printed 500mm wide parabolas and I managed to make it quite cheap.
If I'm alone, it's 22€ but if we're 3 of us it goes down to 12,5€ per person for the full parabola.
I planned to do it in clear resin because it leaves things open for the decoration ( I attached an example).
Any feedback? Anyone interested?
Attachments
I'm surprised the price is that low for 3D printing. In the U.S. I'd expect a part that size to be 5 times that or more, depending on the material used.
The clear SLA items I've had printed have yellowed over time. It might be worth asking about the light stability of the material if you intend to rely on its transparency for decoration. There are newer materials out that might do better in this regard, so it may not be an issue.
The clear SLA items I've had printed have yellowed over time. It might be worth asking about the light stability of the material if you intend to rely on its transparency for decoration. There are newer materials out that might do better in this regard, so it may not be an issue.
Ok my bad, I did some changes on the unit on Blender and it changed the model size, price is not relevant anymore, sorry for the late night enthusiasm...
The Peerless driver does quite well with a full-range signal as long as you don't do anything rude to it. For near listening within its power rating, you should be fine with no crossover. Just wire it directly to your amp.
As with any new speaker or design, take it easy in the beginning until you have a feel for what it's capable of. As long as you creep up on the volume, it will safely let you know when you're over driving it.
I like to start designs as simple as possible. It's easy to add a filter later if you want to limit low frequencies. If you wind up needing complex equalization and decide to use DSP, a more effective crossover can be done there.
As with any new speaker or design, take it easy in the beginning until you have a feel for what it's capable of. As long as you creep up on the volume, it will safely let you know when you're over driving it.
I like to start designs as simple as possible. It's easy to add a filter later if you want to limit low frequencies. If you wind up needing complex equalization and decide to use DSP, a more effective crossover can be done there.
Thanks again for your advice, everything worked pretty much easily and as expected.
So, I managed to put my hand on all the recommended stuff and it works pretty well in a passive mode using my home amplifier but when assembling the whole stuff I realized that what I want to achieve is an amplified speaker.
Would you have any recommendation to embed a good amplifier on the device?
I have seen stuff like TDA7850 DIY kits
Do you think it makes sense? (I could use the two other channels later on to connect a bass driver to the concept as an option)
Any other recommendation that would fit my concept? (stick as much as possible to audiophile quality for a reasonable price knowing the limitations of the parabola reflection strategy)?
So, I managed to put my hand on all the recommended stuff and it works pretty well in a passive mode using my home amplifier but when assembling the whole stuff I realized that what I want to achieve is an amplified speaker.
Would you have any recommendation to embed a good amplifier on the device?
I have seen stuff like TDA7850 DIY kits
Do you think it makes sense? (I could use the two other channels later on to connect a bass driver to the concept as an option)
Any other recommendation that would fit my concept? (stick as much as possible to audiophile quality for a reasonable price knowing the limitations of the parabola reflection strategy)?
If you want to use a small amplifier module built into the device itself, I don't have much experience with those. The concept seems logical though. It's one I've considered for computer speakers also.
A lot of the amplifier modules are class D now with limited power. The main thing to watch on class D is that many are rated at 10% distortion, so you'll typically want a higher powered module in order to keep the power used in the clean portion of its output. The better modules have clear data on power vs. distortion, with ratings for low distortion wattage also.
On any premade module, I'd look for ones that have a lot of positive reviews. Some of this stuff is pretty bad for noise, turn on/off thumps, reliability, etc.
At work I use an Audioengine N22 integrated amp for my computer speakers. It's 22 watts per channel and class A/B. For near listening, it does pretty well. It's small, but is a separate component.
A lot of the amplifier modules are class D now with limited power. The main thing to watch on class D is that many are rated at 10% distortion, so you'll typically want a higher powered module in order to keep the power used in the clean portion of its output. The better modules have clear data on power vs. distortion, with ratings for low distortion wattage also.
On any premade module, I'd look for ones that have a lot of positive reviews. Some of this stuff is pretty bad for noise, turn on/off thumps, reliability, etc.
At work I use an Audioengine N22 integrated amp for my computer speakers. It's 22 watts per channel and class A/B. For near listening, it does pretty well. It's small, but is a separate component.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.