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Why is there 3+ and 3- on this 8ohm subwoofer?

 

New member
Username: Ted1ba1r

Post Number: 1
Registered: Aug-10
Hi i have 3 x Cambridge 210w 8ohm Sub woofers (taken from creative gigaworks s750 7.1's) and i want to connect the all together to make a much more powerful home audio sub but i hit a problem when i saw they had 3 positives and 3 negatives.
(Pictures Attached)

Does anyone know why there is 3+ & 3- ?

What is the best way to connect them up? i was thinking Series/Parallel to keep the Ohms down to a manageable level.
Would that work?

&

What is the best amplifier to get to drive all 3?

Thanks for any help you can give.

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Gold Member
Username: Magfan

USA

Post Number: 1522
Registered: Oct-07
Have you 'ohm'd' between the various connections to try to determine HOW they are wired?
Is there a 'jumper' anywhere? The usual 'thing' is for DVC subs to be connectable in series OR parallel,

Could the other terminals be used to 'pass thru' a signal to additional speakers? Your ohm meter can help with that, too.
 

New member
Username: Ted1ba1r

Post Number: 2
Registered: Aug-10
I haven't "ohm'd" it yet as I don't have any thing to test the speaker.
It is possible that they might for "pass through" because the sub had a built-in amp that powered 7x70w satellites and the 210w sub.

there is nothing on the speaker other then what you see going into the voice coil.

How do you think i should test the speaker? such as connect all the - and the + together and testing them with a multi meter? or signally?
I'm totally new to all of this stuff so I don't have a clue.

I'm grateful for all your help.
 

Gold Member
Username: Magfan

USA

Post Number: 1524
Registered: Oct-07
I'd examine it more before starting in with the soldering iron and wire clippers!
Look behind the connector tabs and see where in the heck all those pesky wires go. If they all disappear into the center, then it would be reasonable to assume they are all connected somehow, as well. This means more work.....for you.
Before heading out for a meter......a big investment if you only need it for this.....try a battery....like a 'd' cell on each pair of wires. When you are golden, the speaker will emit a little pop or click. You can also feel it move. Just connect the battery for a sec, than disconnect. Don't leave it 'on'.
connect from red to black....one at a time. Do all combinations. Note what does / doesn't click.


All the speakers in this mess were run from this module? So the little satellites got a feed from this unit?
Nows time for a quick trip to Radio Shack. You may have other places available. Buy a cheapo DVM. 40$ or 50$ will get you a reasonable meter with sufficient flexibility. Don't buy a 200dollar Fluke or whatever......You simply don't need that kind of meter, which can be calibrated and may have other features.

Next, start measuring between wires. Use the lowest resistance scale. Keep track of all readings. Make up some kind of table and just fill in values. Red/Black is first. Keep in mind where any wire connected to the backside of the tab goes.......

Finally, I see the cambridge soundworks stamp. Any way to get a schematic? Mechanical or Electrical drawing? That'd make the whole exercise one of just following wires.

ONCE you figure out the electrical wiring, you've got the box / enclosure to figure out. That is the start of yet another mess. Got an amp? Got woodworking tools? Know how to figure box size?
It is getting complicated. Sure you want to try this?
 

New member
Username: Ted1ba1r

Post Number: 3
Registered: Aug-10
All of the wires are going from the terminals into the voice coil but after they go in i have no idea how they are wired up.

I have tried the battery test you were saying and every + & - make the popping sound just like you said.

I will borrow a DVM from a friend so it saves me buying one myself.

I will try contact Cambridge Soundworks and see if they can tell me anything.

As for the enclosures, I still have them from when they were bought ready built so even though there will be 3 single enclosures at least they will suited to the sub already in them.

what would you advise for these subs? the amp that is built in was a BASH amp but no idea the spec of it.

i was just going to wire the subs to a phono jack and then to an amp but the fact it has 3+ and 3- really baffled me lol

Thanks for the advise.
 

Gold Member
Username: Magfan

USA

Post Number: 1525
Registered: Oct-07
I've pretty much reached my limit.

Do all combinations of + / - produce a click?
You'll need to use an ohm meter to 'see' what's inside.
Take careful notes. Draw if you must. Just measure everything you can.
I'm baffled, since maybe I don't have enough info::
 

New member
Username: Ted1ba1r

Post Number: 4
Registered: Aug-10
Only each + & - pair click. not when I try to cross wires with other + & - pairs.
I will get a ohm meter and test the speaker.
You and me both that's all the info I can give, I have emailed Cambridge Soundsworks to see if they can help in any way so lets hope they can shed light on the speakers design.
 

New member
Username: Ted1ba1r

Post Number: 5
Registered: Aug-10
I used a Fluke 75 and that's the reading I got :
1st pair of +&- I was getting 8ohm
2nd pair of +&- I was getting 8ohm
3rd pair of +&- I was getting 8ohm

When I put all 3+ and 3- together I get 4ohm

Each pair are not connected to the other pairs at all and I get no readings when I try different combinations.
Does this mean that if I connect all 3 +&- together I could use a 4ohm amp?
 

Gold Member
Username: Magfan

USA

Post Number: 1546
Registered: Oct-07
3 @ 8 ohm resistors together in PARALLEL.....all +s together and all -s together should be 2.67 ohms.

Did you try all combinations? .....somethin' don't mesh.

What else do you know? What other pieces do you have?

What do you get when you wire them in SERIES? This should be 3x8 or 24 ohms.

Any help at all from Cambridge Soundworks?
 

New member
Username: Ted1ba1r

Post Number: 6
Registered: Aug-10
Each single pair of + & - give the reading of 7.5ohm
in parallel they give 2.6ohm
in series they give 24ohm

I have tried every combination and the only way I get a reading is from each pair of + & - if I try them with the other pairs of + & - I get no readings what so ever.

Cambridge Soundworks have not yet emailed me.

All I have is the enclosure and the sub the amp that is built in is finished so its unusable.
 

Gold Member
Username: Magfan

USA

Post Number: 1547
Registered: Oct-07
Thanks for digging out better numbers.

It would appear you have a TRIPLE voice coil speaker since each pair of wires produces a 'click'. Not that it actually matters, but I've never heard of such a thing.

good job borrowing the Fluke.

The amp may be 'finished' and 'unusable' but if it isn't a melted down, charred piece of wreckage, maybe you can figure out a few things from it.
I'd try to figure out.....
If the 3 sets of wires to the speaker came from their own individual amp inside the bigger box. Were other speakers driven from this amp? Stereo input? one of the 3.5mm plug ends to your sound card would qualify.......
Can you post a picture of the 'wreckage' ?
 

New member
Username: Ted1ba1r

Post Number: 7
Registered: Aug-10
Thanks for the advice,

I was looking around the internet and on a Russian forum some guy reckons its a 3 coil speaker so maybe there is such a thing as a triple coil speaker after all.

As for the pics I will have to dig out the enclosure and show you what the amp looks like.

I would not have a clue what to do with the amp or how to tell what things do.
 

New member
Username: Ted1ba1r

Post Number: 8
Registered: Aug-10
Hi i have got the pics for you to look at and where they go to on the amp its self i dont know anything more other then what i have shown you.

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New member
Username: Ted1ba1r

Post Number: 9
Registered: Aug-10
The gigaworks s750 amp
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New member
Username: Ted1ba1r

Post Number: 10
Registered: Aug-10
Side view of the ampUpload
 

Gold Member
Username: Magfan

USA

Post Number: 1569
Registered: Oct-07
Marcus,
Looks like 3 amplifiers.....from what little I can see. OK pics, though.

I'd deep-six it and start over. There are many, many practical problems. Enclosure and size is just a start.

If you want to DIY a sub....maybe a good place to look would be Madisound or Parts Express. You can buy a sub driver and a plate amp. You can than either build an enclosure, have one built....you've got some handy buddies, right? OR buy one from where you get the rest of the goods.

I'm currently enrolled in woodshop up at the local JC with just such an intent.
 

Bronze Member
Username: Ted1ba1r

Post Number: 11
Registered: Aug-10
Hi Leo,
Thanks for the reply.
I have the enclosures already so I just need to get the sub working really.

I found that a electrical shop near me sell a 200w Power Amp
http://www.maplin.co.uk/Module.aspx?ModuleNo=46467

don't know if this will do the job, I don't want to drive it to hard just so I can use it with my TV.
I also found the Toroidal Transformer to power the amp and I know that I will only get 100w rms at 4 ohms 200w peak what would be your opinion on this?
 

New member
Username: Zaandrei

Post Number: 1
Registered: Feb-11
Hello, sorry for trying to resurrect such an old post, but I also need some help with this. I want to change my S750 sub to something better. From my opinion the sub seems to 'bottom out' too often so i think that a 10" or a 12" car sub would run perfectly fine with the 210W RMS that this 8" is getting.

Is there a way to hook up those '3 amps' that went to each of the 3 voice coils to ANY car sub? Im talking a sony explode with 4x4 ohm voice coils or anything that is fairly common? Thank you very much!

PS: I don't know too much about this, i am 17 :$
 

New member
Username: Psvita84

Post Number: 1
Registered: Jan-17
Sorry for reacting in an old topic, but the question form the user Zaandrei is exactly my question. Did you solve this Zaandrei? or does anyone else have a solution?
 

New member
Username: Mojtaba

Post Number: 1
Registered: May-17
hey , i have the same problem here i have s750 speaker but the sub die each time i repair it i really getting tired to fix it again and it cost too much to fix but u already know after the fix u can't use it more than 2-3 months , now im just use another 5.1 channel amp that came from my old speaker that connected to the s750 speakers ( sattlite speakers ) and sub is old sub-woofer came from the old 5.1 amp , is there any car amp that can handle this 210 RMS sub-woofer and for those don't know about the 3 coil sub i can tell them the amp makes 3x 70watt amp that each one connected to each voice coil there are 3 voice coil + and - ( red - black ) cable to the sub so its 3 voice coils that each one needs 70watt and 3 70watts will be 210watts that make it sense . any idea which kind of card amp can handle this sub ? i just want to forward the sub-woofer output from my sound card to a car amp then connect the amp to my sub and i want to only use the card amp for this sub-woofer what do u recommend for using for this kind of job ? its easy but still i can't test it with all amp around the world to see which one can handle ? please try to make it out i can help a lot of people that use s750 speakers set around the world because they all have faulty amp and power supply board on this speaker set u can easily find it why when u google creative s750 repair !
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