[BobSaysHi]

lmao. I wouldn't have spent so much on your speakers and bought new ones.

 

[TheLaw]

Well here's the thing. If this doesn't work out, I'll have some brandy new speakers for another setup. But it'll work.

 

[googleborg]

i just decided to do my logitech sub, works a treat, though can't test at any kind of volume at this time in the morning....
 

 
connects via 2 phono to the tape outs on my amp, the squiggly wires on the volume pot are for support ^_^ thought about using those caps but i couldn't get them to fit, oh well...hotwired the on switch cable to ground so it's always 'on' now, bass is adjusted on the back of the sub.
 
shame i don't have a drill, could have mounted it all in the sub itself.  will report back tomorrow on this £10 subwoofer
 
 
 

 

[googleborg]

Quote:

Sorry for being so ignorant about this. I decided I would take apart the powered sub...Easier said than done. I wound up destroying the box....Of course, I didn't harm anything else, but I guess I'll have to be building me a new sub box sometime...
 
Anyway, the model number is Z313. It cost me $30 on sale....Does the job mostly.
 
Not sure how huge these pics are going to be, but here it goes....As you can see, really cheap stuff on board. It's not like they really have a choice....for the price they want to sell at. I think I'm going to replace value for value on the electrolytic caps with a higher quality alternative. I might see if I can get a better sub. Again, it was cheap, so I don't really mind messing with it too much. 
 
Oh and yes, the inline volume adjuster absolutley sucks. How should I fix that? It cracks and I have to fine tune it to get both satellites working at the same time...Pretty annoying
 
Caps by Chang, CapXon and Samxon. All general purpose as far as I can discern.  Pretty crappy....Note the LOVELY rectifier circuit.
 
The heat sink for this thing has about as much potential as a piece of aluminum foil.
 
Too much inrush current....Hmmm....Bigger heatsink to cover that?
 
It has a massive transformer by the way. Don't know the actually output spec, but I think it would have to be fairly decent. Probably either @ 16V or 25V.

nice pics you've actually got better quality parts in there than my ubercheap one, but the sub is the same as my other logitech i think, but i've no intention of hacking that one up haha...
 
"Too much inrush current" inrush current is the juice the main filter caps initially draw from the mains as they fill up, too much and you'll nuke your fuses, even the rectifier diodes probably, but your diodes look quite beefy, might handle a little increase in capacitance?  there is bound to be a way of calculating inrush current with voltage and capacitor size and ESR and stuff, but i don't have a clue

 

[TheLaw]

Wow that looks interesting. I see a pot and some other stuff. What exactly did you do to it? I'm kind of confused. =D
 
Quote:

i just decided to do my logitech sub, works a treat, though can't test at any kind of volume at this time in the morning....
 

 
connects via 2 phono to the tape outs on my amp, the squiggly wires on the volume pot are for support ^_^ thought about using those caps but i couldn't get them to fit, oh well...hotwired the on switch cable to ground so it's always 'on' now, bass is adjusted on the back of the sub.
 
shame i don't have a drill, could have mounted it all in the sub itself.  will report back tomorrow on this £10 subwoofer
 
 
 

 

[TheLaw]

Haha. Thanks. Yeah, I decided to get new caps all around. I decided to just get the same capacitance on the input because of space limitations...They should be here tomorrow or Friday, and I'll recap the board. I'll be sure to post some pictures. When's the last time you've seen a logitech sub with Nichicon Muse? Oh wait...never....

 

[TheLaw]

Quote:

Quote:

Sorry for being so ignorant about this. I decided I would take apart the powered sub...Easier said than done. I wound up destroying the box....Of course, I didn't harm anything else, but I guess I'll have to be building me a new sub box sometime...
 
Anyway, the model number is Z313. It cost me $30 on sale....Does the job mostly.
 
Not sure how huge these pics are going to be, but here it goes....As you can see, really cheap stuff on board. It's not like they really have a choice....for the price they want to sell at. I think I'm going to replace value for value on the electrolytic caps with a higher quality alternative. I might see if I can get a better sub. Again, it was cheap, so I don't really mind messing with it too much. 
 
Oh and yes, the inline volume adjuster absolutley sucks. How should I fix that? It cracks and I have to fine tune it to get both satellites working at the same time...Pretty annoying
 
Caps by Chang, CapXon and Samxon. All general purpose as far as I can discern.  Pretty crappy....Note the LOVELY rectifier circuit.
 
The heat sink for this thing has about as much potential as a piece of aluminum foil.
 
Too much inrush current....Hmmm....Bigger heatsink to cover that?
 
It has a massive transformer by the way. Don't know the actually output spec, but I think it would have to be fairly decent. Probably either @ 16V or 25V.

nice pics you've actually got better quality parts in there than my ubercheap one, but the sub is the same as my other logitech i think, but i've no intention of hacking that one up haha...
 
"Too much inrush current" inrush current is the juice the main filter caps initially draw from the mains as they fill up, too much and you'll nuke your fuses, even the rectifier diodes probably, but your diodes look quite beefy, might handle a little increase in capacitance?  there is bound to be a way of calculating inrush current with voltage and capacitor size and ESR and stuff, but i don't have a clue

Haha. Thanks. Yeah, I decided to get new caps all around. I decided to just get the same capacitance on the input because of space limitations...They should be here tomorrow or Friday, and I'll recap the board. I'll be sure to post some pictures. When's the last time you've seen a logitech sub with Nichicon Muse? Oh wait...never....

 

[googleborg]

interesting eh...yes this is the first time i've done something like this, wasn't sure where to start haha...
 
i chopped the pod off and desoldered all the bits off it to use later then i got a motorised alps pot i took out of a very dead yamaha AX-396 amp (yamaha seem to use all elna/nichicon caps fwiw), along with the phonos and a 3 wire ribbon cable scrap, and wired it all together, at first i had soldered the power on wire to the right channel, not ground, and was like 'why is this humming so badly?', then i rectified the mistake and put it all back together, am quite pleased that i never broke it honestly if it passes mustard when i use it tomorrow i'm keeping my eye out for cheapy second hand PC subs on ebay to perhaps do an upgrade jobbie on...my NAD amp has two tape outs so i could use two identical subs O_o
 
 
and for curiosities sake the inside of the satellite speakers....my thumb looks odd...

 
i think that circular thing on the end is the magnetic shielding or something.

 

[googleborg]

the sonic results in short; for electronica type stuff - great! extends to bass down nicely, but with rock and such, just not high enough quality, bass sounds disembodied...i think the quality of the driver and the crossover point setting has a lot to do with this.

 

[raindog1975]

@TheLaw , I modified a pair of Logitech x140 ( even cheaper and crappier then your speakers ; I just wanted a small system for my work bench and I have experience in building and repairing speakers and amps ) with good results. I would suggest you use a metal enclosure for your amp ( to avoid EM interference  ) and put the power supply ( transformer and rectifier bridge+smoothing cap ) in a separate enclosure or at least use a separate board for the rectifier and place it as far as possible in the enclosure from the main board . Also is  a good idea to use the ground on the rectifier board as ground connection for the speakers ( to avoid creating a ground loop ). To improve the power supply you can also use 0.1uF polyester or even ceramic caps  in parallel with each rectifier diode and place one in parallel with the smoothing cap ( btw a bigger one - 6800 uF ar even 10000 uF wouldn't hurt providing you use the 5amp diodes ).

 

[raindog1975]

P.S. a good source of information about amplifiers , power supplies , grounding etc are Rod Elliot's articles : http://sound.westhost.com/articles.htm

 

[raindog1975]

@googleborg , the "circular thing on the end" is indeed magnetic shielding -the cheap version , it's just a another magnet glued to the pole piece in opposite polarity with the main magnet - good quality shielded speakers use a metal can over the magnet .

 

[googleborg]

oh right, i hope it's glued on well else it might fly off or something ^_^
 
thanks for the link, have added it into my electronics folder in chrome

 

[raindog1975]

don't worry , it won't fall of , just don't keep the speakers too close to the monitor ( the "shielding" isn't very effective ).

 

[raindog1975]

P.S. another good source of information ( on everything related to audio ) is www.diyaudio.com