need stereo aplifier for 4 2" 5Watt 8Ohm driver speakers.

[johnathon007]

I am thinking of buying 4 of these **broken link removed** and im looking for a simple and cheap driver circuit for them to play from my ipod and use them for my laptop sound. It wont need amazing sound or anything but i also dont want them to sound like crap. I think they pulled them from ipod docks like MM50 PORTABLE SPEAKERS FOR IPOD OR IPOD MINI 3IN DRVRS LITH-ION at PartStore.com.
Thanks for reading this whole thing

 

[audioguru]

The tiny 2" speakers resonate at 147Hz in free air then the resonance will be 220Hz or higher in an enclosure. Therefore no bass.
Their sensitivity is very low so they will sound faint.
Yeah, they will sound like crap without the 3" mid-bass woofers.
I have a computer speaker system with little 2" shriekers (they are too small to be called speakers) and a 4" woofer that sounds pretty good.

A TDA7240A amplifier IC can provide an output of 5W RMS at clipping into 8 ohms with a 12V supply. The schematic and pcb design are in the datasheet.
Two are needed for stereo.

 

[johnathon007]

Thanks for the information, these will be part of a portable system so the acoustics are secondary to size and power consumption and from some of the reviews on the sale page the frequency response seems to be beyond most mp3's anyway.
I know there is very little chance this will work but i was just thinking what would 2 of these do unamplified from an mp3 player ? ive got a couple portable speakers that have cheap paper cone speakers and i was just wondering if i could directly replace them, they would only need to be loud enough to hear within 10 feet or less. If they arent good for what i want i could always amplify them but would this even work at all ?

 

[audioguru]

these will be part of a portable system so the acoustics are secondary to size and power consumption and from some of the reviews on the sale page the frequency response seems to be beyond most mp3's anyway.

An MP3 player has a frequency response of from 20Hz to 20kHz like our hearing. Those tiny speakers are too small to produce any bass sounds. Use headphones instead like a few people did in the reviews.
The reviews agree with me that the tiny speakers (shriekers) produce no bass. Most people buy speakers to produce good sounds, not just small size. These ones are not sensitive so they have high power consumption.

 

[johnathon007]

I would like to keep this around $20 so with that in mind do you have any suggestions for alternate speakers ? Would 2 of these and 2 3" woofers make a more complete sound ? And how long would i be looking at running this on AA batteries [the 2700mAh rechargable ones] how many doesnt really matter as long as its still compact enough to carry easy. Also i have a few mid ranges from old systems so if i throw in 2 of **broken link removed** would that give it a good amount of bass ?

 

[audioguru]

You will not have good quality sound with such cheap and small speakers.
The 3" speakers resonate in free air at 98Hz and in enclosures will resonate at about 150Hz. Then there will be no deep bass but the upper bass will be much better than the 2" shriekers. They have an Xmax of only 1mm (woofers must move much more so they might be straining to produce upper bass). They are not sensitive but since they are 4 ohms then they might be loud enough with a max power of 9W each. An LC crossover network must be used for each channel.

One charge of your 2700mAh battery will produce loud stereo at an average of 1W per channel (9W max per channel into the 4 ohm woofers) for 8 hours. The battery will last much longer if the volume is reduced.

35 years ago I made a similar sound system for the beach. I used two 3" speakers and one 4" woofer. It sounded better than any other sound system on the beach and much better than "ghetto blasters". It was a "chick magnet" but I am married and my wife is always with me. My cute little dog is also a "chick magnet".

 

[Hero999]

I found a reasonable quality dual cone speaker in Rapid electronics. It's not a woofer but it would be suitable for the speakers.

**broken link removed**
**broken link removed**

 

[audioguru]

The Visaton 4" speaker also does not produce deep bass. It cuts off at 90Hz to 100Hz which are mid-bass frequencies..

 

[Hero999]

The Visaton 4" speaker also does not produce deep bass. It cuts off at 90Hz to 100Hz which are mid-bass frequencies..

I know, I didn't say it did.

 

[johnathon007]

Most of my music is rock so mid bass is where most the sound is, i found that raising the 100hz range gives the biggest increase on my computers suround. And really since im making a portable system i can deal with less then perfect sound.


EDIT>> I have a friend who has this system https://www.amazon.com/Logitech-Portable-Speaker-System-Black/dp/B000FOG8LQ I cant find its frequency range but maybe you can, im happy with anything near as good as that.

 

[johnathon007]

Just wondering if anyone knows where to find the frequency response on the system in my last post? I cant find it on any sales sites and its not on any of the packaging my friend got when he bought it.

 

[audioguru]

Just wondering if anyone knows where to find the frequency response on the system in my last post? I cant find it on any sales sites and its not on any of the packaging my friend got when he bought it.

The Logitech MM-32 amplified speaker system is cheap and small. Logitech has no spec's for it. Its owners manual also has no spec's.
Its speakers are only about 1" so i would think it has a fairly flat frequency response down to 300Hz or 400Hz and its output power is very low because it uses only four AA cells for power.

 

[johnathon007]

ive decided to get 2 of these **broken link removed** along with 2 of my original choice and am building my amp from 2 TDA2030A TDA2030 18W Hi-Fi Amplifier 35W Driver and i now need some advice on the crossover and if possible a simple diagram to follow. I was thinking a 150-14000 range for the 2" and a 75-4000 for the woofer should be around the right numbers, correct me if im wrong.

 

[transistor495]

The Logitech MM-32 amplified speaker system is cheap and small. Logitech has no spec's for it. Its owners manual also has no spec's.
Its speakers are only about 1" so i would think it has a fairly flat frequency response down to 300Hz or 400Hz and its output power is very low because it uses only four AA cells for power.

Well, 100USD for the little and simple goody doesn't look cheap for me. I'd be much interested to know more about those 1" drivers.

Anyhow, low frequency response can't be expected from such a simple unit and I'd say...it's a crap at that price.

It was a shock for me that headphones like Denon AH-D2000's are priced at something 500USD's. It would be nice to experience what they offer at this price. Also I dunno what's a microfiber material is -what they've used for constructing the diaphragm.

 

[audioguru]

I would never buy a speaker like that surplus 4" woofer that does not have a datasheet to show how flat or peaky is its frequency response.

I think 150Hz is too low for the crossover frequency because those tiny 2" speakers might not go that low. Low frequencies damage small speakers.
Almost all stereos with satellite speakers and a woofer or two use a crossover frequency of 300Hz.

You do not need to limit the woofer from going below 75Hz. In an enclosure it won't go below 100Hz anyway. it is important to have the same crossover frequency for the woofer and tweeter so you do not have the peak from the woofer at a few kHz and so that you do not have phasing adding and cancelling when two speakers near each other play the same frequencies.

You also do not need to limit the tweeter from going above 14kHz. Most of us can hear to 20kHz and we don't know how high your little 2" speakers can go.

 

[johnathon007]

I think i know your opinion on small speakers but i found these **broken link removed** and they seem to have a much better frequency range . Now for someone like me who is not looking for any real chest pounding bass but instead just something to listen to my ipod in my yard or at the beach would these be good enough, i really am just trying to get some of the information on all the options but i would preffer this thing could go in a small bag or even a pocket and also be loud enough to hear for 10-20 feet.

 

[audioguru]

Have you ever heard headphones playing when they are sitting on a table? That is what those tiny little speakers will sound like.
No bass sounds.
Very low level since the sensitivity is very poor.
The response drops above 12kHz so the sizzling highs will be missing.
Let us know how bad the sound is.

Tang Band have some 4" full-range speakers that sound good when they are in huge transmission-line enclosures.

 

[johnathon007]

I was just asking becuase yesterday we took my friends mm32 to a skate park and you could hear it well from all sides 100 feet away, and up close it had some pretty good bass considering its size, so ive kinda been on a search for the speakers they use.

 

[audioguru]

People listen to MP3s on a hi-fi sound sytem at home, on a car sound system with a sub-woofer or on headphones when out. Then they hear and feel all sounds from 20Hz or less to 20kHz.
You are different because you are happy hearing 300Hz to 12kHz, something like a telephone.

 

[johnathon007]

i just got one of these Amazon.com: DB Portable Foldable Speakers for Mp3 Players - Black:… to give myself some perspective on the sound quality, they are rated 200-18k but they reproduced 150-19k just fine without distortion on medium volume. But at the same time they dont sound near as good as the mm32 so i have to guess that the mm32 goes down to at least 100 and probably up to 19k at least. I loaded some test tones on my mp3 player to test this and i hope to get over to my friend with the mm32 and test his to verify. I just thought id share my finding just in case someone was interested.