Hi, I would like to create a small, portable speaker for spoken word listening that would work with my mobile phone. I was wondering if someone could recommend an easily available compact transducer and a fitting class D power amplifier.
I watch a lot of video and YouTube documentaries and science videos on both my phone and on the PC, and I am unhappy with my current listening arrangement.
- the phone itself isn't loud enough, so if my AC is on, if I'm cooking, vacuuming, or the audio track is too quiet, I can't hear it well enough.
- the Bluetooth speakers I have tried (both via BT and aux in) are very bass boosted and make the speech unintelligible.
- the same thing applies to my PC speakers, so I would likely use this small portable speaker for watching YouTube on my PC as well.
I would like a speaker that is good for speech in itself. This is not an audiophile endeavor, so I don't need maximum fidelity, instead I want clear speech and little bass. Yeah, I could high pass filter it, but it's better if the transducer itself doesn't extend lower than 100s of Hz, because that simplifies the design.
I would like to put it in a small plastic or metal enclosure, roughly the size of my phone, and attach it to the back of my phone with a neodymium magnet. The box shouldn't be much thicker than the phone (10-15mm), so I guess that means normal paper cone style speakers are out of the question. I think a design similar to a headphone transducer would be more suited, but i don't know what that type is called and how to search for it. My first thought was to purchase a transducer for some model of AKG headphones, since those are relatively inexpensive, but I am not sure how loud those can go for extended periods of time before failing.
A fitting class D power amplifier would be necessary, bearing in mind that this is battery operated.
I would like to keep this low in cost, around ~50-70 Euro in parts. Thanks for reading. I would be grateful for any suggestions or pointers.
Edit: I this is obviously not a multi-way speaker, but I couldn't find a better board for this - if there is one please let me know!
I watch a lot of video and YouTube documentaries and science videos on both my phone and on the PC, and I am unhappy with my current listening arrangement.
- the phone itself isn't loud enough, so if my AC is on, if I'm cooking, vacuuming, or the audio track is too quiet, I can't hear it well enough.
- the Bluetooth speakers I have tried (both via BT and aux in) are very bass boosted and make the speech unintelligible.
- the same thing applies to my PC speakers, so I would likely use this small portable speaker for watching YouTube on my PC as well.
I would like a speaker that is good for speech in itself. This is not an audiophile endeavor, so I don't need maximum fidelity, instead I want clear speech and little bass. Yeah, I could high pass filter it, but it's better if the transducer itself doesn't extend lower than 100s of Hz, because that simplifies the design.
I would like to put it in a small plastic or metal enclosure, roughly the size of my phone, and attach it to the back of my phone with a neodymium magnet. The box shouldn't be much thicker than the phone (10-15mm), so I guess that means normal paper cone style speakers are out of the question. I think a design similar to a headphone transducer would be more suited, but i don't know what that type is called and how to search for it. My first thought was to purchase a transducer for some model of AKG headphones, since those are relatively inexpensive, but I am not sure how loud those can go for extended periods of time before failing.
A fitting class D power amplifier would be necessary, bearing in mind that this is battery operated.
I would like to keep this low in cost, around ~50-70 Euro in parts. Thanks for reading. I would be grateful for any suggestions or pointers.
Edit: I this is obviously not a multi-way speaker, but I couldn't find a better board for this - if there is one please let me know!
Interesting project.
So I'd set off with one of those tiny class D boards that'll run on 5V power. That way, your power supply is a USB port.
After that, I'd go for analogue input in the form of a trailing 3.5mm (headphone) cable.
For the speakers themselves, I'd probably purchase an aluminium project box of the right size, and cut/grind with something like a dremel.
I'd prioritise cone area primarily - find something that looks like it'll do the job, and stuff as many as you can into the space you have.
It won't be HiFi, but will probably get over 90dB.
Alternatively, you could get a few laptop speaker modules (they usually come with their own little plastic enclosure) and stick them together. Nice and easy.
Chris
So I'd set off with one of those tiny class D boards that'll run on 5V power. That way, your power supply is a USB port.
After that, I'd go for analogue input in the form of a trailing 3.5mm (headphone) cable.
For the speakers themselves, I'd probably purchase an aluminium project box of the right size, and cut/grind with something like a dremel.
I'd prioritise cone area primarily - find something that looks like it'll do the job, and stuff as many as you can into the space you have.
It won't be HiFi, but will probably get over 90dB.
Alternatively, you could get a few laptop speaker modules (they usually come with their own little plastic enclosure) and stick them together. Nice and easy.
Chris
Agree and add: lots of flat speakers (search for them), both around 1.5 inch for notebooks as suggested above, or round 1 3/4 inch transparent plastic cone for door-to-home intercoms.
2" Mylar Cone Full-Range Waterproof Speaker D0050008NM14BAR
This one is 45 ohm but they are widely available in 8 ohm, a few in 4 ohm for pocket radios and such.
You might even recycle a cheap pocket radio junking the tuner part and leaving case, amp, speaker and battery holder.
It will be easy to find some plastic case, maybe one to carry pencils or similar, at nearest dollar store.
You should be able to find a Class D BTL amplifier board (stamp sized) which runs out of a 3.7V surplus cellphone battery, so it´s fully independent from mains.
As of equalization, all are flat, which to you means "not clear sound, too much bass"
Once you found your amplifier, post it here and I´ll suggest how to equalize it for telephone quality sound; what you need, , is cutting bass and low mids below 600Hz or so ... not kidding.
What remains above that is articulate and intelligible.
I have the same problem as you, want to hear voice, such as News, Podcasts or Audiobooks while sawing/power sanding/routing wood/spraying when building Guitar speaker and amplifier cabinets in my shop, go figure.
2" Mylar Cone Full-Range Waterproof Speaker D0050008NM14BAR
This one is 45 ohm but they are widely available in 8 ohm, a few in 4 ohm for pocket radios and such.
You might even recycle a cheap pocket radio junking the tuner part and leaving case, amp, speaker and battery holder.
It will be easy to find some plastic case, maybe one to carry pencils or similar, at nearest dollar store.
You should be able to find a Class D BTL amplifier board (stamp sized) which runs out of a 3.7V surplus cellphone battery, so it´s fully independent from mains.
As of equalization, all are flat, which to you means "not clear sound, too much bass"
Once you found your amplifier, post it here and I´ll suggest how to equalize it for telephone quality sound; what you need, , is cutting bass and low mids below 600Hz or so ... not kidding.
What remains above that is articulate and intelligible.
I have the same problem as you, want to hear voice, such as News, Podcasts or Audiobooks while sawing/power sanding/routing wood/spraying when building Guitar speaker and amplifier cabinets in my shop, go figure.
Last edited:
Until I know, telephone BW is from 300 to 3000Hz, like FM 0.7, 2 and 6 mts ham bands.
I would suggest using a (phone) power bank as the power source, as it already contains all required charging and protection electronics. A PAM8403 3 W amplifier runs for days on a 2200 mAh power bank. The power bank must be bypassed with a capacitor of at least 2200 µF.
Last edited:
Yes, I'm planning to use a power bank.
I don't want to use a HPF. Laptop speakers are a good tip, as are intercom speakers. I don't really want to bypass the PSU since that will shorten battery life due to leakage resistance, but a powerbank shouldn't have an issue powering a class D amp, right?
a cutoff of 600 Hz is fine to me. I don't care about the low frequency components of speech as much.
I don't want to use a HPF. Laptop speakers are a good tip, as are intercom speakers. I don't really want to bypass the PSU since that will shorten battery life due to leakage resistance, but a powerbank shouldn't have an issue powering a class D amp, right?
a cutoff of 600 Hz is fine to me. I don't care about the low frequency components of speech as much.
If you have any other tips for high output speakers around 2" or less and 10 mm or less in thickness, please keep them coming.
I don't think the capacitor's leakage resistance will shorten the battery life by much.
A problem I had with mine was that my battery pack kept shutting down because the amplifier didn't draw enough current.
Chris
A problem I had with mine was that my battery pack kept shutting down because the amplifier didn't draw enough current.
Chris
Bypassing the power bank was required on mine because it couldn't keep up with the current surges drawn by the amplifier. Without bypassing, amplifier output power was limited.
This one luckily had no problems with shutting down, it always presented 5 V on its output (even when 'turned off').
This one luckily had no problems with shutting down, it always presented 5 V on its output (even when 'turned off').
Last edited:
- Status
- Not open for further replies.