Clever bass from small wireless portable speaker

[speakermagic]

I am new to the forum and interested in small speakers with big sound. I recently came across some wireless (bluetooth ) speakers that I repaired for a friend of mine. I was amazed at the sound and quite rich sound these speakers make. They are 57mm diameter and 60mm high with a 45mm speaker and a built in 3W amp. They work great on a kitchen bench or any surface that can resonate a bit. The kitchen stainless steel sink or the acrylic bath in the bathroom is quite amazing. Steel filing cabinet works well also.

They way they work is very clever and have not come across this before so I thought I would share it with you as it may be of some interest. I do apologise for the poor blurry photos but at least it may give you an idea of what I am trying to explain.

They have a clever pseudo subwoofer arrangement where the speaker frame has an extra rubber surround on the outside and the surround is glued to the enclosure. This allows the whole speaker to move and act as a subwoofer. It has a very small cavity and relies on the surface it sits on to pick up the vibrations. It works surprisingly well for such a small speaker.

Here are a couple of links of the two types I have played with.

Aliexpress.com : Buy Portable My Vision A61 Mini Bluetooth Speaker Stereo Loudspeaker red free shipping from Reliable bluetooth Speaker suppliers on Shenzhen Haotai Technology Co., Ltd.

Monster beatbox s10 mini bluetooth speaker - China Monster beatbox s10 mini bluetooth speaker Supplier, Manufacturer - Shenzhen MBEATS TECH Co.LTD

fake beats by dre mini bluetooth speaker is loud enough to move itself!! - YouTube

I would be interested in any suggestions for making a reasonable small enclosure to augment the bass when no suitable surface is available. That bath in the bathroom sounded impressive but can't carry a bath around. LOL
I am also interested in any small enclosure speakers (full range) with good bass like mini TL. I enjoyed going through the thread foam core material to make enclosures and the cornu spiral horn.

 

[howardg]

I have wondered about those type of surface exciting type drivers. We go to so much trouble to make precise enclosures and still have mixed results, I have doubted that the sound from a table top vibrating could really be high fidelity. That doesn't mean that there aren't times when we are out and about when having a full sound from a very small package could be desirable, despite strictly lacking in fidelity.

I have heard blue tooth(?) type speakers with mp3 players that were amazingly full sounding for their size and price, but I would not want to sit down to listen to music from one at home when I have better options.

That said, if you wanted to experiment, maybe you could get an old, cheap acoustic guitar from a thrift shop and remove the strings and place the speaker on that. It seems like that would make an efficient and balanced sounding resonator that is not too big or heavy. If you like the way it sounds, cut off the neck with a metal cutting saw( because the internal tensioning rod, assuming there is one, would damage a wood saw).

 

[xrk971]

I have had luck putting these into a miniature folded MLTL like a Tabaq. Do a search for Tabaqube and you will see the 4 fold TABAQ that has 2x2 in CSA and 36 in total length. Trick is to use very light stuffing and the bass output is actually pretty good.

 

[speakermagic]

Thanks for the suggestions. Have you come across this type of psuedo sub design where the whole speaker/frame moves?

 

[xrk971]

I think you are talking about a passive radiator but I don't think these are really are designed that way. I think if it moves it is coincidence as the bellows is really there to allow the collapsible feature. When expanded the volume is bigger providing more bass. There are diy passive radiator designs around where you take regular driver and add mass to cone with bolts, etc.

 

[speakermagic]

I am not talking about the bellows hamberger type. This has a real roll rubber surround arround the outside edge of the speaker frame that then attaches to the enclosure so the whole speaker moves (frame and all).

 

[Cal Weldon]

The latest take on the Biflex design. Great idea for small drivers.

 

[xrk971]

Ok, I have never seen this biflex as Cal calls it. Do you have photo or link? I guess mass of the driver frame and magnet acts as the passive rad?

 

[speakermagic]

I could not find anything on the net that shows it. Only the crappy photos above.

 

[xrk971]

Ok I think I see the outer surround you are talking about. Your photos are pretty blurry This would be an interesting concept to model. Is the photo the Aliexpress or the Monster beat pro?

 

[speakermagic]

Its the Aliexpress one that is in the photo. I like the Monster Beatbox a bit better as it has a TF card in it and it is a bit louder. I expect both are using the same principle.

 

[speakermagic]

This may show the speaker better with the surround on the outside of the frame.

 

[Cal Weldon]

Here's the Altec Biflex. Similar principal, different implementation.

 

[xrk971]

This may show the speaker better with the surround on the outside of the frame.

Where did you get the Solidworks 3d models? Is this from manufacturers website?

 

[speakermagic]

It is a sketchup model that I got from the 3D warehouse and then mmodified

 

[badman]

This seems most accurately described as a passive radiator, with potentially large IMD issues from the modulated mounting.

 

[speakermagic]

I had a chance to take some better pictures.

 

[picowallspeaker]

Ohhh now I see...
Not bi-flex but total- flex .
BTW 4Ω-3 W is a power figure for... a tweeter

 

[speakermagic]

Its only a very small speaker having a cone diameter of only 28mm.

 

[speakermagic]

Most of the speaker diameter is taken up by the surronds.