Ratings of small speakers

[carbonzit]

so can i use them as microphone , the small one is out of headphone. i dont care about voice quality , it should just be audible.

I think that question has already been answered. Speakers are commonly used as microphones in audio devices where quality is not a concern, for instance in intercoms.

what will be the current produced by big speakers when someone speaks into them , can it be amplified , or will i have to buy new microphone ?

Look up intercom circuits. How much current? Not much.

how can a speaker have DC resistance when it is just a winding of wire along a magnet ?

Well, think about it a second. Even a coil of wire has some resistance. The longer the coil, the higher the resistance.

 

[audioguru]

so can i use them as microphone , the small one is out of headphone. i dont care about voice quality , it should just be audible.

Yes, the little speakers can be a poor quality microphone but their output level is very low (like a microphone) so it will need a pre-amplifier circuit.

what will be the current produced by big speakers when someone speaks into them , can it be amplified , or will i have to buy new microphone ?

The output level is about 5mV when talking at conversation loudness 20cm from your mouth. it needs a pre-amp to increase the level to drive a power amp that drives a speaker.

how can a speaker have DC resistance when it is just a winding of wire along a magnet ?

A winding of thin wire that is maybe 5m long has resistance.
Measure the DC resistance of hundreds of speakers to see it. Then measure the DC resistance of 5m of thin wire to see it.

 

[transistor495]

Loud Speaker Back emf

I would like to point out an interesting fact here.

A comparatively big woofer( say 5", 20W ) coil can light up an LED connected directly to its terminals if you beat on the dust cap using hand. I think not many of you've noticed this.

This back emf should definitely be affecting the performance of the unit especially of sub-woofers. Any comments

 

[carbonzit]

This is where things like damping factor come into play. (Look it up.)

 

[Sceadwian]

That's why you don't impedance match audio systems transistor, you general want the lowest possible output impedance for a speaker system, because the lower it is the higher the damping factor, and why if at all possible full DC coupling is preferred over AC, again superior damping.

 

[audioguru]

A 15", 18" and 22" woofer is big. They produce strong very low frequencies.
A little 4" or 5" "woofer" is not big. It is low power and does not produce deep bass frequencies.

 

[carbonzit]

A 15", 18" and 22" woofer is big. They produce strong very low frequencies.
A little 4" or 5" "woofer" is not big. It is low power and does not produce deep bass frequencies.

Again, your reply is so irrelevant. The person you're responding to said "A comparatively big woofer( say 5", 20W ) coil can light up an LED connected directly to its terminals if you beat on the dust cap using hand.". They didn't claim the woofer had deep rich bass; they only claimed it could light up a LED. (Which I plan to verify in my own laboratory very soon.)

Moderated.

 

[carbonzit]

A speaker can light up a LED

I would like to point out an interesting fact here.

A comparatively big woofer( say 5", 20W ) coil can light up an LED connected directly to its terminals if you beat on the dust cap using hand. I think not many of you've noticed this.

Well, I certainly had never noticed this. But thanks for bringing it to our attention.

Guess what? It works.

I hooked up a 6" woofer[1] to a breadboard and tried some LEDs. The all lit up very nicely when I thumped on the cone with my hand. (Had to orient them correctly to the polarity of the pulse.) I used a bunch of regular old low-brightness LEDs, all salvaged from various pieces of discarded electronics.

I didn't think it would be able to light a "high brightness" white LED, but I was wrong; I got a really bright flash out of it (a 28,000 MCD one from Digi-Key, 3.something volts).

One thing about the speaker you use is that it should have a fairly high-compliance suspension so the cone can move enough to generate a good-sized pulse.

Hmm, I wonder if this has any practical application? A battery-less pulse generator?


Moderated OT.

 

[transistor495]

A 15", 18" and 22" woofer is big. They produce strong very low frequencies.
A little 4" or 5" "woofer" is not big. It is low power and does not produce deep bass frequencies.

My premium quality Creative T40 speakers rocks with 2.5" drivers

 

[audioguru]

My premium quality Creative T40 speakers rocks with 2.5" drivers

Bass frequencies go down to 20Hz that you can feel. The Chinese Creative tiny little 2.5" driver goes down to about 200Hz which is barely a low frequency. Each tiny 2.5" midrange driver is fed with up to 7W. Each speaker has two tiny midrange drivers and one dome tweeter. Each speaker has a "bass" port that produces lower midrange feequencies. There is no provision to add a woofer nor subwoofer.

 

[transistor495]

The Chinese Creative tiny little 2.5" driver goes down to about 200Hz which is barely a low frequency. Each tiny 2.5" midrange driver is fed with up to 7W.

This is pretty underrating of my beautiful speakers

Mine is Series II so it has 16W RMS per channel and 32W total. It goes down near to 50Hz I would say and the overall frequency response is excellent.

It is made in Creative Tech. Singapore.

 

[audioguru]

This is pretty underrating of my beautiful speakers

Mine is Series II so it has 16W RMS per channel and 32W total. It goes down near to 50Hz I would say and the overall frequency response is excellent.

It is made in Creative Tech. Singapore.

Each speaker has two tiny 2.5" midrange drivers.
Since you have Series II then each tiny driver gets 8W instead of the original 7W but you won't hear any difference.
Read the reviews about the very good midrange sound the tiny 2.5" drivers produce. Some reviews say the low frequencies are muddy and distorted. The spec's say "frequency response 50Hz - 20kHz" but without any + or - dB listed the response can be anything.

 

[Sceadwian]

audioguru, you're still deliberately misstating the reality to the detriment of anyone wanting to learn anything about audio

The Chinese Creative tiny little 2.5" driver goes down to about 200Hz which is barely a low frequency.

Is absolutely positively completely false, and demonstrable by anyone with a pair of ears and the ability to hear, there were no claims of linearity, and certainly it's not high fidelity flat frequency response for the form factor the speakers are decent though.

Would you care to qualify the db limit for low frequency response because there are no standards for it that I'm aware of and your huffy attitude does little to educate anyone.

 

[audioguru]

audioguru, you're still deliberately misstating the reality to the detriment of anyone wanting to learn anything about audio

I am not misstating anything!
Reality is that deep bass sounds are produced by a pretty big woofer, not from these tiny little things.

All half-decent speakers have a frequency response spec'd at plus and minus 3dB (double the power or half the power) which most people can hear as a small change in level.
Cheap speakers spec the frequency response at plus and minus 10dB or 20 dB which is horrible because then the response is all over the place. No bass and very loud treble or no treble and loud boomy bass. Maybe no bass and no treble but a very loud midrange. Maybe no midrange but but very loud bass and treble.
Very poor speakers do not state how many dBs their response is off. This Chinese speaker with the tiny drivers does not say how many dBs it is off.

A 15" or 18" high quality woofer produces bass frequencies down to 20Hz or 25Hz at -3dB.
A 12" high quality woofer produces bass frequencies down to about 25Hz or 30Hz at -3db.
A 10" woofer produces bass frequencies down to about 30Hz or 40Hz at -3dB.
An 8" woofer produces bass frequencies down to about 50Hz at -3dB.
A 5" woofer produces bass frequencies down to about 80Hz at -3dB.
A 4" woofer produces bass frequencies down to about 100Hz at -3dB. No deep bass.
A 3" very high quality speaker produces bass frequencies down to about 150Hz at -3dB. No deep bass.
A tiny high quality 2.5" midrange speaker produces frequencies down to about 200Hz at -3dB. No bass.

It is a small, fairly inexpensive computer speaker system, not a hi-fi speaker system.

 

[Sceadwian]

Okay, so you've defined the hi fidelity system to be the 3db cutoff for frequency? What about linearity and total harmonic distortion?

 

[audioguru]

No speaker manufacturer spec's linearity or distortion because all half-decent speakers are mechanically linear.
A speaker that is spec'd at plus and minus 3dB is very linear in its frequency response and will sound good.

Some amplifiers produce high and horrible distortion.