Hi!
I am new to the forum and the DIY audio world so I was hoping some of you guys could help me out a bit
.
I am going to build my first "real" portable speaker. I build a simple one before but I was not very satisfied with the result.
I have a few questions about things Im not entirely certain of:
First of all, the goal is a "good" sounding portable speaker to use at the beach, in the yard and so on. So nothing extremely fancy.
I would like my speaker to be as small as possible without major performance loss.
For a small enclosure I read that I should go for a sealed design. I think I will go for a passive radiator design as this tends to be better as just a sealed box. I thought I would just put in passive radiators 2x the size of the drivers, so 4x the same size PR as driver. (or is it not that simple?).
When I bought these drivers I had never heard of EBP. When calculating this, its clearly meant for a ported enclosure with an EBP of 127. Is it a bad idea to still use a passive radiator enclosure? (as this is easier to make and can be smaller)
According to the documentation of the drivers I bought (see links) The sealed volume should be 0.12 cubic ft. with some filling, how much (if any) smaller can I make this without very noticeable performance loss?
And last, I am planning to make my own 2-way crossover as I assume the assembly of this is not too hard. I calculated the crossover point with VituixCAD. Is this recommended for a beginner? I want the speaker to sound good, so maybe buying one is wiser?
woofers (2x):
Dayton Audio RS125-4 5" Reference Woofer 4 Ohm
Tweeter (1x):
Dayton Audio DSN25Ti-4 1" Titanium Dome Neodymium Tweeter with Steel Frame 4 Ohm
ANY other advice or tips are very much appreciated!
Thanks in advance!
I am new to the forum and the DIY audio world so I was hoping some of you guys could help me out a bit
.I am going to build my first "real" portable speaker. I build a simple one before but I was not very satisfied with the result.
I have a few questions about things Im not entirely certain of:
First of all, the goal is a "good" sounding portable speaker to use at the beach, in the yard and so on. So nothing extremely fancy.
I would like my speaker to be as small as possible without major performance loss.
For a small enclosure I read that I should go for a sealed design. I think I will go for a passive radiator design as this tends to be better as just a sealed box. I thought I would just put in passive radiators 2x the size of the drivers, so 4x the same size PR as driver. (or is it not that simple?).
When I bought these drivers I had never heard of EBP. When calculating this, its clearly meant for a ported enclosure with an EBP of 127. Is it a bad idea to still use a passive radiator enclosure? (as this is easier to make and can be smaller)
According to the documentation of the drivers I bought (see links) The sealed volume should be 0.12 cubic ft. with some filling, how much (if any) smaller can I make this without very noticeable performance loss?
And last, I am planning to make my own 2-way crossover as I assume the assembly of this is not too hard. I calculated the crossover point with VituixCAD. Is this recommended for a beginner? I want the speaker to sound good, so maybe buying one is wiser?
woofers (2x):
Dayton Audio RS125-4 5" Reference Woofer 4 Ohm
Tweeter (1x):
Dayton Audio DSN25Ti-4 1" Titanium Dome Neodymium Tweeter with Steel Frame 4 Ohm
ANY other advice or tips are very much appreciated!
Thanks in advance!
The Xmax of your 5" woofer is 4.0mm so you would require two 5" PRs, each of Xmax 4.0mm, to match one woofer.
Re crossovers - you will get better results designing and building your own - they need not be too complicated for your application.
Or, just one of these per woofer since it has Xmax = 8.0mm.
Opentip.com: Dayton Audio DS135-PR 5" Designer Series Passive Radiator
The maths:
Surface area of cone (Sd) x maximum cone excursion (Xmax) = volume of air displaced (Vd).
The PR(s) should have twice the Vd of the woofer.
Your woofer: Vd = 75.4 x 0.4 = 30
The DS-135PR 5": Vd = 75.4 x 0.8 = 60
Opentip.com: Dayton Audio DS135-PR 5" Designer Series Passive Radiator
The maths:
Surface area of cone (Sd) x maximum cone excursion (Xmax) = volume of air displaced (Vd).
The PR(s) should have twice the Vd of the woofer.
Your woofer: Vd = 75.4 x 0.4 = 30
The DS-135PR 5": Vd = 75.4 x 0.8 = 60
The 'boominator' thread has great info for a portable build. I wouldn't try passive radiators or anything complicated / fancy to extend the low end. No matter what you do, it won't go very low.
If you really want low end in a small, portable package, use headphones
Another option could be to refurbish an existing device, like an 80's boombox - that is, get something that's already working OK, and apply one upgrade at a time (calss D amp, rechargable battery).
That might be an easier / more encouraging project for a noobie.
If you really want low end in a small, portable package, use headphones
Another option could be to refurbish an existing device, like an 80's boombox - that is, get something that's already working OK, and apply one upgrade at a time (calss D amp, rechargable battery).
That might be an easier / more encouraging project for a noobie.
Where would you say it gets too complicated for a noobie?
the passive radiators themselves are now fairly easy to find (just look for a Vd twice as big as my drivers).
The volume of the cabinet was given with the drivers.
The crossover will be a challenge to know when its 'right' but the design should not be that complicated.
I have made a portable battery before so that should work just fine.
I still have to figure out where to place the drivers, but there is an equasion for that (something like 13,500/crossover frequency)
oh and ill have to read up some more about the whole baffle step and diffraction.
So offcourse it will not be optimal because its my first real build, but I feel like I can get it at least 80% right if I put enough time in it.
Or am I being too shallow now?
the passive radiators themselves are now fairly easy to find (just look for a Vd twice as big as my drivers).
The volume of the cabinet was given with the drivers.
The crossover will be a challenge to know when its 'right' but the design should not be that complicated.
I have made a portable battery before so that should work just fine.
I still have to figure out where to place the drivers, but there is an equasion for that (something like 13,500/crossover frequency)
oh and ill have to read up some more about the whole baffle step and diffraction.
So offcourse it will not be optimal because its my first real build, but I feel like I can get it at least 80% right if I put enough time in it.
Or am I being too shallow now?
I mean passive radiators are over complicated, for the application. It is hard to get bass outside - a system that's flat indoors will be bass shy outdoors.
In a small package, for outdoor use, I wouldn't even attempt to get a system to play low - particularly for taking to the beach, where the bass output will be competing with wind & wave noise.
That Dayton driver looks fine for indoor, close range listening. It will have a F3 of about 60Hz in a 5 litre ported box, and that seems pretty good. However, the calculated efficiency is only 85dB (note that this is 10dB less than the tweeter you nominated).
mh-audio.nl - Home
Peak SPL at 60Hz will be roughly 90dB (excursion limited), meaning it won't go very loud even if you could throw lots of power at it.
By comparison, if you stuffed a 6" Faital 6FE100* into the same size sealed box, the F3 would shift up to about 90Hz, which seems like a bad thing.
But IMO, the benefits would be worth it: calculated efficiency is 4dB higher, meaning you'd double your battery life. The peak SPL will also be higher by about 5dB (excursion limited), because it is a bigger driver, with slightly more Xmax.
The tuning you get (from stuffing this 6" into a small box) will give about 1.7dB of midbass boost (around 150Hz), which will help give the impression of fuller bass. Indoors, that might sound a bit boomy. Outdoors, I think it would be a good thing.
*just an example. A pair of smaller drivers might work even better.
I agree with hollowboy that high sensitivity and an upper bass boost (rather than low bass extension) would be desirable for a battery operated system which is to be used outdoors.
You say you have already bought the Dayton drivers so will need to concentrate on getting the best performance out of them. However, that does not necessarily mean using passive radiators.
I would have a good look at the ported option before committing yourself to the additional expense of passive radiators.
You say you have already bought the Dayton drivers so will need to concentrate on getting the best performance out of them. However, that does not necessarily mean using passive radiators.
I would have a good look at the ported option before committing yourself to the additional expense of passive radiators.
Since the resonant frequency of the tweeter is 1,705Hz, you need a crossover of at least twice that frequency (say 3,500Hz) using a Second Order Crossover (12dB/octave). You will also have to attenuate the tweeter by 5dB using an L-pad in order that it matches the lower sensitivity of the mid/woofer.
This design calculator will get you going:
Speaker Crossover Calculators by V-Cap
Welcome! And yes, we will be glad to "help" you with a welter of contradictory opinions + a wild surfeit of mind-overloading informationHi! I am new to the forum and the DIY audio world so I was hoping some of you guys could help me out a bit
Google "Hoffman's Iron Law" to see why this is not possible, due to physics. Or maybe you already get this per your EBP reference.
Ported speakers have more output, with less excursion of the main driver, near the port frequency. Below that frequency, the port becomes a short (say that 10 times fast!) and unloads the main driver, whose excursion can go nuts. The port tuning is a consequence of the air volume in the port (a mass) versus the air volume inside the box (a spring). Thus, tiny enclosures cannot be tuned really low except by a tiny port...which cannot flow enough air to be meaningful. Passive radiators can *somewhat* get around this if you can load enough mass to tune them low, but there's a limit to that. To a first approximation, a passive radiator is a ported system. The delay of the air starting to move through the port means the time response of a ported system is not as good as a sealed design, though how noticeable vastly depends on a lot of factors. In my experience, I don't want any response bump at all. That could sound "more full" but could "sound like sh$t."
Sealed systems by contrast offer somewhat less bass, with more controlled excursion and tighter sound.
For an outdoor small speaker, I really wouldn't worry about baffle step response and so on, unless you just want to which is cool.
As for the crossover, mmm, do you have any way to actually measure the drivers? Without actual data things can work, but maybe not optimally. Once upon a time, back during the last Ice Age, I calculated a crossover out of a book and painstakingly built the whole thing...then ended up with a giant cancellation, since the actual response magnitude and phase didn't match the assumptions. And no, I don't trust data from different manufacturers, since they always use somewhat or even radically different equipment and setups.
This is indeed mind-overloading information. But I love it!
I really want to learn more about this and know how to build an optimal system.
I HAVE SO MANY QUESTIONS
@head_unit: how much would I need to spend to get a cheap measuring mic? And by that I mean something that I can use for future projects but not for the insane audiophile measurements.
Maybe you have some suggestions?
@Galu: That was indeed what I was hoping for, but I guess it's not as easy as it seems!
@hollowboy: I don't really understand what just happened here:
"The tuning you get (from stuffing this 6" into a small box) will give about 1.7dB of midbass boost (around 150Hz), which will help give the impression of fuller bass. Indoors, that might sound a bit boomy. Outdoors, I think it would be a good thing."
What do you guys mean by "midbass bass boost" and "upper bass boost" and how would I select drivers for a small boombox like mine?
I intend to also make some speakers for when I move into my new room. So these drivers are probably more suitable for a project in that environment I guess?
Maybe I will buy some new drivers for this project then..
From what I have just learned (please correct me if I'm wrong) I am looking for a driver that:
Has a low F3 so I get decent bass from a small driver.
high sensitivity to get enough sound from low power.
which of course brings us back to head_unit's mention of the Hoffman law where if I want a small enclosure this is not possible.
So I guess I will have to compare a lot of them and make the trade offs!
For the new driver selection, should I go for a build plan to get me started on making a crossover and stuff?
Or do you guys say just go for it and it will be fine haha
I really want to learn more about this and know how to build an optimal system.
I HAVE SO MANY QUESTIONS
@head_unit: how much would I need to spend to get a cheap measuring mic? And by that I mean something that I can use for future projects but not for the insane audiophile measurements.
Maybe you have some suggestions?
@Galu: That was indeed what I was hoping for, but I guess it's not as easy as it seems!
@hollowboy: I don't really understand what just happened here:
"The tuning you get (from stuffing this 6" into a small box) will give about 1.7dB of midbass boost (around 150Hz), which will help give the impression of fuller bass. Indoors, that might sound a bit boomy. Outdoors, I think it would be a good thing."
What do you guys mean by "midbass bass boost" and "upper bass boost" and how would I select drivers for a small boombox like mine?
I intend to also make some speakers for when I move into my new room. So these drivers are probably more suitable for a project in that environment I guess?
Maybe I will buy some new drivers for this project then..
From what I have just learned (please correct me if I'm wrong) I am looking for a driver that:
Has a low F3 so I get decent bass from a small driver.
high sensitivity to get enough sound from low power.
which of course brings us back to head_unit's mention of the Hoffman law where if I want a small enclosure this is not possible.
So I guess I will have to compare a lot of them and make the trade offs!
For the new driver selection, should I go for a build plan to get me started on making a crossover and stuff?
Or do you guys say just go for it and it will be fine haha
Put these books on your Christmas list. A bit more basic knowledge can't hurt!
The Loudspeaker Design Cookbook: Amazon.co.uk: Vance Dickason: 9780962419171: Books
Designing, Building, and Testing Your Own Speaker System with Projects: Amazon.co.uk: David Weems: 9780070694293: Books
The Loudspeaker Design Cookbook: Amazon.co.uk: Vance Dickason: 9780962419171: Books
Designing, Building, and Testing Your Own Speaker System with Projects: Amazon.co.uk: David Weems: 9780070694293: Books
The box shapes the low frequency response of the loudspeaker.
Scroll down in this link to find out about the effect of Qtc.
speaker basics
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