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Old 11th September 2014, 03:39 PM   #1
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Default please Help me progress

I feel really lost.
I am trying to design a small speaker which has to be portable and wireless.
The electronics has somehow been figured out.
Now remains the main task of designing an enclosure. Though there are numerous 3 and 4 inch drivers, but I am not able to figure out which would be suitable to build inside a small sealed enclosure.

The dimension I have in mind is 8(W)x4(H)x3(D). This feels OK to me as it can be atleast carried around comfortably.

I tried with Vifa tc9fd. Then there is Faital Pro 3fe22 and 3fe25. A parts express guy told me, with luck, you may be able to use Dayton Audio ND90 or ND91.

But seriously, none seems to fit inside that enclosure dimension. I mean the sound is little harsh and bass sucks. In my previous thread someone suggested me to have baffle step compensation to correct the harshness. I am not looking for a jaw dropping bass, somewhere from 60 or 70 or 80 hz will be fine.

Now how can I get that from such a dimension. I guess trying different drivers seems the first choice, but due to bad luck I ran out of money.

Most of the online calculators says that with the dimension, f3 would be at around 120 or 130hz. I even tried reducing the wood thickness from 12mm to 6mm. No luck. Ported may help but, even though I havent tried, there can be issue of noise et al(Parts express guy warned me. I know to first try and then agree. But i kind of feel low now). I got from calculation, a .45 inch dia, length around 2.5 inch.

Pls can you tell me or guide me about correcting the sound inside those enclosures for those drivers, lot of money has been spent. Or if you know of a better and more powerful driver which will be happy inside that enclosure, do tell me. There should be, coz there are many commercial sets available which are even smaller than my dimension and sound pretty decent.

I dont want to give up now coming this far.

thanks.

Ps: winisd doesnt work with windows 7. When i input specs for faital pro it says compliance issue with many groups. bass box pro, someday will buy.
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Old 11th September 2014, 04:34 PM   #2
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C'moooon, why do you want to "enclose" the sound ?
As you need "only" to let the sound come from the front, and "entrap" the back wave.
If the back wave finds an ambient too small, it will push the pressure back to the cone. When the volume it's just right, the air vibrates at resonance, with the help of a duct ( Bass reflex) and the cone finds little resistance in motion.
So it's not a matter of no/poor/good bass, well, it follows...
Quote:
I got from calculation, a .45 inch dia, length around 2.5 inch.
I would use a 1" duct!
Or try double reflex chambers, lamination, trasmission line
Most important is the filling! ( it augments the volume "virtually" till 30 % )
And also the wood ( ?? still using wood ) should be very thick, or make a layer of laminated stell on it.
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Old 11th September 2014, 04:40 PM   #3
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I'm no expert but
The bass will 'suck' if spl is shy at the lower end - because the ear finds it harder to pick up bass,
If you want bass I can only suggest doing a ported design ensuring adequate power is available (what amplifier are you using?), I know myself now that with diy project you have to be very patient.

I have to say Jawbone Jambox is really big on bass for it size.
I'm not sure what wizardrygoes on inside, resonances and filtering etc, maybe would be worth researching it.

Also with x-mini portable speakers - sticking them onto some surfaces enhances the bass slightly , I know I stuck two in stereo onto a 16" cardboard box and that is quite 'loud'.
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Old 11th September 2014, 05:19 PM   #4
Greg B is offline Greg B  United States
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Sounds like you're trying to make one of the mini extension/bluetooth speakers like people use with their phones/ipods?? I haven't taken apart any of the current crop of micro speakers, but they most likely use active filtering to EQ the response. If they didn't, they wouldn't have bass either. Efficiency is sacrificed for small size. Pick a small driver with as much xmax as possible. Yeah, the nd90 or nd91 would probably work.

With the vifa TC9FD you need some baffle step compensation. Physics: it's the law! An inductor and resistor will be needed to reduce the mids and trebles. (or build an active shelving filter into your electronics)

Last edited by Greg B; 11th September 2014 at 05:21 PM.
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Old 11th September 2014, 05:58 PM   #5
xrk971 is offline xrk971  United States
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In addition to EQ, almost all the top portable bluetooth compact speakers use a passive radiator. You can't fit a long enough port with enough cross sectional area into a small box, hence the PR.

I have looked into this extensively before and arrived at this conclusion which has not changed. I love diy, but....

My suggestion would be to buy one of those blue tooth speakers and not mess around with a diy. By the time you got all the parts and amp and EQ, your cost would be well more than one of those and it may not sound as good. If you relax your size requirement to something biggger in the 8 to 10 liters volume you may be able to diy it. Another option is to buy a pc desktop speaker with PR's and add battery power supply. Check out Logitech X140:
What’s Inside? The Logitech X-140 Speakers | rennie ash ?

Or spend $80 and get the Logitech UE boombox with passive radiator:
Logitech UE 984-000298 Mobile Boombox
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Old 11th September 2014, 06:52 PM   #6
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Quote:
Originally Posted by picowallspeaker View Post
C'moooon, why do you want to "enclose" the sound ?
As you need "only" to let the sound come from the front, and "entrap" the back wave.
If the back wave finds an ambient too small, it will push the pressure back to the cone. When the volume it's just right, the air vibrates at resonance, with the help of a duct ( Bass reflex) and the cone finds little resistance in motion.
So it's not a matter of no/poor/good bass, well, it follows...

I would use a 1" duct!
Or try double reflex chambers, lamination, trasmission line
Most important is the filling! ( it augments the volume "virtually" till 30 % )
And also the wood ( ?? still using wood ) should be very thick, or make a layer of laminated stell on it.
1. Does it also mean to have some kind of sound/air absorbent material inside the walls, so it doesnt push the cone back? will it help.(i actually used 12mm marine plywood)
2. the concept of resonance in relation to speakers, i confuse it sometimes. what is it? i know about blowing the bottle thing. But in relation to speakers what is it? how does it matter, and when enclosure calculators spits out those values for diif parameters, what does it suggest?
3. i dont know anything about injunction molding. so going by wood.

(FYI - my amp is TA2024)

Last edited by arjunm009; 11th September 2014 at 06:55 PM.
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Old 11th September 2014, 06:55 PM   #7
Greg B is offline Greg B  United States
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Quote:
Originally Posted by xrk971 View Post
In addition to EQ, almost all the top portable bluetooth compact speakers use a passive radiator. You can't fit a long enough port with enough cross sectional area into a small box, hence the PR.

I have looked into this extensively before and arrived at this conclusion which has not changed. I love diy, but....
Passive radiator - yeah, that's the only thing that makes sense. Your conclusion also makes sense. I don't think any money is going to be saved vs a commercial product. Sometimes DIY is the more expensive way to go.

If all the materials have been purchased already, there's always that .4 scaled mini karlsonator for vifa tc9fd. The design of the cabinet essentially does the BSC mechanically. Not quite micro mini, but it's pretty small. (certainly smaller than I ever imagined for this design...)
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Old 11th September 2014, 06:58 PM   #8
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Quote:
Originally Posted by giro1991 View Post
I'm no expert but
The bass will 'suck' if spl is shy at the lower end - because the ear finds it harder to pick up bass,
If you want bass I can only suggest doing a ported design ensuring adequate power is available (what amplifier are you using?), I know myself now that with diy project you have to be very patient.

I have to say Jawbone Jambox is really big on bass for it size.
I'm not sure what wizardrygoes on inside, resonances and filtering etc, maybe would be worth researching it.

Also with x-mini portable speakers - sticking them onto some surfaces enhances the bass slightly , I know I stuck two in stereo onto a 16" cardboard box and that is quite 'loud'.
I am using a TA2024 amp.
When you said about sticking onto a surface, so instead of traditional drivers, if i use a vibration speaker, i dont have to worry about those T/S parameters anymore?
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Old 11th September 2014, 07:00 PM   #9
xrk971 is offline xrk971  United States
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Quote:
there's always that .4 scaled mini karlsonator for vifa tc9fd. The design of the cabinet essentially does the BSC mechanically. Not quite micro mini, but it's pretty small. (certainly smaller than I ever imagined for this design..
That design is rather cute and sounds very nice with bass down to about 75-80Hz. One nice thing about it is that it weighs nothing when made of foam core. Very portable units to take along with a simple class D amp for boombox duties. I have used it as such.
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Old 11th September 2014, 07:20 PM   #10
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I think I would go with Fiatal Pros'. They are anycase louder than vifa.
So if i install passive radiators, what should be its dimensions then. I guess it is in some correlation to a port but exactly what would it be. As i said, for my calculations for a tuning Freq of 70hz, the port was 2.5 inch length and .45 inch dia(even though noise can be a problem, right?). In relation to that what should be the passive radiator size?

Also when talking about EQ, is it Speaker Zobel / Impedance Equalization Network Circuit Calculator. Then where will I add a baffle step compensation circuit?
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