Mini Boombox based on my "Macaroni" speaker

[V-bro]

New project for some friends who want sound on the road...




Related threads:
http://41hz.com/forums/topic.asp?TOPIC_ID=1917
http://41hz.com/forums/topic.asp?TOPIC_ID=1789

It's not finished yet, it'll have:

-220V PS in the box
-Volume control
-Four source input selection with RCA sockets in the back
-12Vdc input

This time I think I'm gonna put a reflex port in there because the casing is relatively large... I'm curious to the difference in the lower end [8D]

------X-max. can be several meters on any driver, too bad it can be done only once...------

[krilli]

Permission to rock GRANTED

[V-bro]

Thanks Krilli, I hope I can get it finished this evening...

I did get all the sockets and bass port in last night...



Some nice RCA sockets for the four inputs and a mains IEC and 4 pin XLR for the 12V:

I put some mesh in the port to prevent bugs to enter and build their nests in there:


------X-max. can be several meters on any driver, too bad it can be done only once...------

[V-bro]

Thanks Krilli, I hope I can get it finished this evening...

I did get all the sockets and bass port in last night...



Some nice RCA sockets for the four inputs and a mains IEC and 4 pin XLR for the 12V:

I put some mesh in the port to prevent bugs to enter and build their nests in there:


------X-max. can be several meters on any driver, too bad it can be done only once...------

[V-bro]

I've been listening to it for the past two days and this evening there were some friends staying over for dinner and they wanted it so bad that I had to give in...

It was a bit of a struggle to make it all happen, first my power supply went up in smoke. It worked perfectly, but when I unplugged it from mains and plugged it in elsewhere the mains fuse blew out and the supply was toasted. Probably cap failure, an often occurring failure in cheap SMPS. It was a very silent supply though...

Then I installed a 4A universal SMPS for laptops and everything seemed to work fine, then I closed the lid and heard a whining noise from the speakers that got louder when I turned up the volume. CURSE SWEAR! This was late at night and I wanted to finish the $#%%&^*$ thing! This is never a healthy attitude, it's always better to give it a rest and continue the other day, but on the other hand I'd sleep better if I knew how to solve it. So I continued anyway. Rigorous measures, I took a piece of sheet metal, iron... Folded it in a Z-shape and covered the whole power supply. Noise was gone...sigh...

It was caused by the audio transformers I placed in the box and the electromagnetic field from the SMPS interfered with the audio signal...

Now it sounds nice, about the same as the active speakers I made before. The fact that it's ported doesn't seem to make that much difference. It's good bass for such a small system, but apparently not better than a smaller closed system. My preference has always been the better controlled response from a closed design and that hasn't changed.

What did "surprise" me again was the stereo imaging. It's VERY good for a small stereo box, that's probably the special Tripath sauce again In any case it's a very handy little box and the input selection makes it pretty versatile. These friends want to bring it along on their camping holidays... I'm sure they'll enjoy themselves with it...

------X-max. can be several meters on any driver, too bad it can be done only once...------

[V-bro]

Oh and here's the final version with power switch and green power led:


------X-max. can be several meters on any driver, too bad it can be done only once...------

[Scratchy]

Very well done - as always.
Now for the question I could not bring myself to ask. but somehow find myself asking anyway.

Where are the noodles? [)]

***It's so easy, everyone should be doing it***

[V-bro]

I must have shaken'em off somehow...[)]

------X-max. can be several meters on any driver, too bad it can be done only once...------

[Kuddeldu]

Almost exactly what i wanted to do built with my AMP32. Therefore i hope you dont mind, if a ask a few questions:

1) How did you connect the PS and the 12V to the AMP? Did you put Diodes between PS and 12V Input? Or are these unnecessary?
2) Have you actually calculated the size of the bass port or did you just "guess" its size?
3) What is the second turn-switch or pot for?

Maybe you can post a picture of the "inner values" of your nice project (only if its not too much effort for you). I am very interested in it :-)

[V-bro]

Hi Kuddeldu, I certainly don't mind to answer a few questions, otherwise I wouldn't have started this thread

1.I have designed a PCB that can hold three large SMD schottky diodes and an SMD polyfuse to separate the 12V input and power supplies and fuse them. If you want one with parts I can send you a kit with all the parts for a very friendly price? The PCB has two isolated holes for bolts as well...

2.I have calculated it first and then tuned it a little further.

3.The two knobs are on for four source input selection and the other for volume control.

I have used a 4A universal laptop supply that has resistor header cartridges to set the voltage very precisely. It's quite nice... But there are many many other ones good enough as well...

The box is from RS components.
http://nl.rs-online.com/web/search/s...821269&x=0&y=0




------X-max. can be several meters on any driver, too bad it can be done only once...------