Hello,
i am new to speaker design. I am inspiried by the Apple HomePod, where the woofer is facing down and the Homepod have 5 tweeters.
So my questions are
i am new to speaker design. I am inspiried by the Apple HomePod, where the woofer is facing down and the Homepod have 5 tweeters.
So my questions are
- is it possible to direct the woofer to the bottom? Does it affect the sound?
- Or it is only possible when the woofer plays only up to 800 Hz and the tweeter plays from this point. 800 Hz due to sound localisation. First research says that frequencys below 800 Hz cant be located by human ear. Is it right?
- is it possible to have more than one tweeter in one speaker?
- How do the tweeters affect on themself? (Interference?)
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Bass is not so directional below more like 100Hz.
Some speakers have many tweeters, in an array or line.
Interference among them is expected and controlled, to an extent.
Some speakers have many tweeters, in an array or line.
Interference among them is expected and controlled, to an extent.
The woofer in the HomePod is upward firing.
This is HomePod 1 but the basic structure is the same (fewer tweeters, mics, and way more compting power in the 2).
Woofers are often used downfiring. Woofers, no matter what direction they fire are omnidirectional at lowest frequencies, but if a downfiring woofer is close to the floor, the distance will mass load the woofer and decrease its HF response.
dave
This is HomePod 1 but the basic structure is the same (fewer tweeters, mics, and way more compting power in the 2).
Woofers are often used downfiring. Woofers, no matter what direction they fire are omnidirectional at lowest frequencies, but if a downfiring woofer is close to the floor, the distance will mass load the woofer and decrease its HF response.
dave
Okay, then it make sense to direct the woofer up. But down firing is not that worse? On the other hand, it means I can design a bookshelf speaker with up firing woofer and have approximately the same sounding speaker?
The other big question is how to deal with more than one tweeter? All example calculations have only one tweeter. What will happen if I arrange a second tweeter on the other side (180°)?
What will happen if I have 4 Tweeters? Is there a rule how to calculate this or is there an explanation how they interference? Constructive interference leads to loud peaks. And destructive interference can cut away a frequency range. And this is not desirable.
https://stereonomono.blogspot.com/2012/06/allison-four.html
The woofer likely has a rising response. Tweeters are splayed, this will be more or less an omni.
There have been a few others, Sonab, here an evolution https://www.stereophile.com/content/larsen-hifi-8-loudspeaker
There is also an omni thread that explores upfiring drivers.
dave
I made a speaker with side woofer. At the beginning the x-over was around 250-300hz and the sound was not ok. After I cut it at 130-140hz the sound was OK.
Sooooo...... the cut frequency must be much lower comparing to the ideea that under 400-500hz the bass is un-directiv.
Sooooo...... the cut frequency must be much lower comparing to the ideea that under 400-500hz the bass is un-directiv.
We did a speaker with 2 side firing woofers (push-push), originally with 250 Hz PLLXO, the guy who did the passive moved it up to 450.
dave
dave
This means for me, that I need a woofer which I can crossover as low as possible. Around 100 to 400 Hz. Since the volume can be a maximum of 6 liter, which woofer can you recommend? Or which parameter I have to look at?
Let's start with the beginning: which tweeters can you use cut at 150-400Hz? There are too few options, I don't know any at the moment. Maybe you should use broadband speakers or switch to 3-way.
And if you want a good extension at low frequencies, you must choose a woofer with a large diameter and able to work in a small volume. When I had a similar question, this selection tool was recommended to me: https://speakerboxlite.com/subwoofer-box-calculator/tab-graphs
And if you want a good extension at low frequencies, you must choose a woofer with a large diameter and able to work in a small volume. When I had a similar question, this selection tool was recommended to me: https://speakerboxlite.com/subwoofer-box-calculator/tab-graphs
Only assume there is a certain amount of "marketing"
To make the apple pie pod attractive to buyers.
Aside from slightly negative view on my standpoint.
Far as real world applications.
Assume there is a tremendous amount of digital processing
to make the overall sound acceptable or even work
Possible to achieve for a Diy project with modern electronics
But might be slightly overkill for a first time project.
and a incredible amount of work to make a bad design
acceptable.
Far as a feasible design for a Diy approach
Omni woofers up down or sideways has been done.
As noted, typical " subwoofer" crossover points 60-120 Hz
will most likely guarantee success for first time build.
Also as mentioned by others side firing or upward designs
have been successful with points approaching typical baffle
step areas or where sound tend behave more full space than
1/2 space 300 to 200 Hz.
If restricted by size restraints, suggest a more conventional
2 way with typical 6.5" to 5 1/4 woofer and tweeter.
Far as suggested " Drivers" there is various " youtuber"
builds which might lend some insight. " 2 guys which
I find annoying but likely have good suggestions.
" Toids" did his "do I need a sub project" or " Dinas"
And his other annoying buddy " Diy Audio Guy"
Otherwise " Sound Blab" has done various very small ported
and passive radiator sub builds.
Likely any of these channels might offer good suggestions
for tiny little sub drivers that do something acceptable
To make the apple pie pod attractive to buyers.
Aside from slightly negative view on my standpoint.
Far as real world applications.
Assume there is a tremendous amount of digital processing
to make the overall sound acceptable or even work
Possible to achieve for a Diy project with modern electronics
But might be slightly overkill for a first time project.
and a incredible amount of work to make a bad design
acceptable.
Far as a feasible design for a Diy approach
Omni woofers up down or sideways has been done.
As noted, typical " subwoofer" crossover points 60-120 Hz
will most likely guarantee success for first time build.
Also as mentioned by others side firing or upward designs
have been successful with points approaching typical baffle
step areas or where sound tend behave more full space than
1/2 space 300 to 200 Hz.
If restricted by size restraints, suggest a more conventional
2 way with typical 6.5" to 5 1/4 woofer and tweeter.
Far as suggested " Drivers" there is various " youtuber"
builds which might lend some insight. " 2 guys which
I find annoying but likely have good suggestions.
" Toids" did his "do I need a sub project" or " Dinas"
And his other annoying buddy " Diy Audio Guy"
Otherwise " Sound Blab" has done various very small ported
and passive radiator sub builds.
Likely any of these channels might offer good suggestions
for tiny little sub drivers that do something acceptable
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Hmm, 13543/pi/400 = 10.78", so quite beaming, but if we accept a typical 8 ft/96" ceiling height as omni, then ~45 Hz.
First I want to say, that I know that the sound can't be so good as a normal 2-way stereo setup. Also, I know that bluetooth speakers or HomePod are not as bad as some here think.
I want to summarize:
I use a woofer with a xo around 120 to 200 Hz. Depends on the higher playing speaker.
I can use a full range speaker for mids and highs.
Or I find a tweeter which I can use with low crossover frequency.
What do you think is the best way to go?
What do you mean with this?
I want achieve a nearly 360° sound. Is it enough to use simply 4 tweeters?
But a bluetooth speaker like this one in the link (jbl) or the HomePod uses woofer and tweeters. It means there must be tweeter with low xo? Or apple use a high crossover frequency for the woofer, but then the sound gets more locatable.
I want to summarize:
I use a woofer with a xo around 120 to 200 Hz. Depends on the higher playing speaker.
I can use a full range speaker for mids and highs.
Or I find a tweeter which I can use with low crossover frequency.
What do you think is the best way to go?
Just pointing out that for a speaker to be close to omni in a typical room it can only happen at low frequencies, so need to define what you mean by 'omni'.
Based on your project, 'omni' means enough drivers to mimic one via mass quantities of comb filtering, some form of DSP.
Hmm, sqrt(200*20000) = 2000 Hz mean
~13543/pi/2000 = ~2.155"/5.475 cm eff. dia.
2.155^2*pi/4 = 3.647"^2/23.543 cm^2 Sd driver.
If it sounds too 'out of of sorts' WRT high speech intelligibility, try tiny super tweeters XO'd around sqrt(2000*20000) = ~6325 Hz.
It's kind of the opposite - a speaker can be omni in a room at high frequencies, but at lower frequencies (modal region) the pressure distribution within the room will depend on the size and shape of the room and the speaker's location within it. But that pressure distribution will not be the same everywhere in a typical room. At frequencies below the lowest mode of the room you can get the same pressure everywhere, but that's usually only at very low frequencies. If you think about an anechoic environment then of course omnidirectivity is much easier at low frequencies. Personally I mostly think about the directivity of the speaker above the modal region of the room I'm planning to use it in. As a rough estimate, say above 500Hz. That's where directivity will effect the type of imaging you get and is the most worth thinking about in my opinion.
Past that, it's quite easy to make a speaker omnidirectional in one plane. Just take a circular driver and point it into a conical-ish reflector. Boom, omni radiation in the plane perpendicular to the axis of the driver. Of course your frequency response will no longer be flat so you will need to measure the response and EQ it. But you probably don't want flat response from an omni system anyway and thus will already need EQ. In most rooms flat response from an omni system will sound too bright. You can stack up drivers for a multi way system kind of like the B&O Beolab 5 (although their reflectors might give more of a directional bias - not 100% sure). In my experience you want the horizontal radiation to have some directivity characteristic - omni or some narrower directivity. For vertical directivity concerns I'd just try to keep the drivers close enough that they don't interfere with each other too close to on-axis around your desired crossover frequency. Something like within a 1/4 wavelength of the crossover works well.
Most people just describe it with subwoofers and being able to tell where the location is or not.
Rather in the Car or average living rooms. Have had subs crossed over as high as 150 Hz
which with some recordings sounded better more detail.
Otherwise with some recordings Bass Guitar in rock music, or Double Bass in Classical
or those darn rebel Jazz guys playing double Bass with their fingers ...LOL
There can be a weird separation or canceling if too much of the instrument is in the sub and the mains.
Also bass drum kicks from real drums can sound weird. and electronic doesnt matter
So its always the usual suggestion that typical 80 to 60 Hz is best for sub to not get
odd sound with a sub.
And more often than not it is the recording and what instruments are involved.
Because even at 80 Hz Some recordings you cant tell where the sub is.
Other recordings its more than obvious.
Have heard it in small cabin space of a car and small to large living rooms.
Still keep my sub usually as close as possibly to the mains.
Rather in the Car or average living rooms. Have had subs crossed over as high as 150 Hz
which with some recordings sounded better more detail.
Otherwise with some recordings Bass Guitar in rock music, or Double Bass in Classical
or those darn rebel Jazz guys playing double Bass with their fingers ...LOL
There can be a weird separation or canceling if too much of the instrument is in the sub and the mains.
Also bass drum kicks from real drums can sound weird. and electronic doesnt matter
So its always the usual suggestion that typical 80 to 60 Hz is best for sub to not get
odd sound with a sub.
And more often than not it is the recording and what instruments are involved.
Because even at 80 Hz Some recordings you cant tell where the sub is.
Other recordings its more than obvious.
Have heard it in small cabin space of a car and small to large living rooms.
Still keep my sub usually as close as possibly to the mains.