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Powering Cambridge 210w 8ohm Sub woofers

Hello People,

On this website you can see a picture of a three voice coil sub woofer:

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Also known as Cambridge 210w 8ohm Sub woofers (taken from creative gigawork s s750 7.1's).

Apperently this is a subwoofer which requires 3 amps of each 70 watts of po wer to bring this beast alive !

I have mine still stuck in my Gigaworks S750 enclousure. I am thinking/woul d like to bring it back alive and thus I would like to replace the very sha dy creative labs electronics with some kind of alternative.

Perhaps the best option is a "plate amp". Apperently this is some kind of p late with some amp electronics attached to it. This could then probably be used to seal the enclosure, it would need to happen to have the same dimens ions.

For now this is an experiment mostly to see if it would work, if it is poss ible and what kind of sound it would give so I can compare it to my memory recollection.

A repairman claims that it is best for the sound quality to have the Gigawo rks fulled repaired/restored, however I am not so sure of that claim and I highly doubt it because I cannot imagine how the electronics would improve the sound of other amps.

However there is some speak of "cross-over" frequencies, though this seems to be handled by software and can be set between 10 hz and 200 hz.

Furthermore the creative x-fi elite soundblaster has 3 outputs on the back which split into 9 outputs via special video cables which are used as audio cables, where one output probably has no signal.

So it seems these cables either duplicate the output signals or split them. I confident that there is a subwoofer signal on one of them, going into my receiver and I could probably connect any amp to the receiver, or perhaps even directly to one of these outputs.

My main issue is:

Will this idea work ? Also how to connect amplifiers to this subwoofer ? Is it as easy as simply plugging some cables into the amp and then connecting it to the 3+ and 3- ?

Also my other main question is:

Which equipment is suited for this ? My guess would be some kind of plate a mp which can deliver 3x70 watts ? Does such an plate-amp exist ?

If it doesn't would I need to buy 3 amplifiers each of 70 watts ? Perhaps d uplicate the subwoofer signal to all 3 with cables ? How would that work ?

An amplifier in a box could also be interesting to play with, but perhaps t he amp plate might be a good solution for this gigaworks if it happens to h ave the same dimensions or otherwise maybe a little bit of extra wood work or so could enclose it ? Perhaps the heatsink of such an amp plate is also enough to cool it and the subwoofer itself doesn't need any cooling.

So please advise if you have any insight or experience into this matter bec ause my experience with "amplifiers" is zero.

I do own a denon receiver 1909 which is used to power the 7 satelitte speak ers and this works fabolously.

My main concern is also the safety of the electronics, I kinda don't trust the gigaworks electronics because of all this brown glue that might have da maged it and the designs looks kinda shady ! ;) :) but perhaps I am a bit t o untrusty of that :) also I like to give other electronics a try just to s ee what it's like.

So if you have any recommendations please share ! ;) It will be very highly appreciated not just by me, but by many many many many owners of gigaworks s750 that have the exact same problem as me.

Bye, Skybuck.

Reply to
skybuck2000
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I have some data sheets available about this device on my webdrive located here:

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(It's a rar file and will need to be extracted with something like winrar, though windows 7 has it also built-in)

Perhaps these data sheets can shed some more light on this device.

Alternative data sheets might also be located here:

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Bye, Skybuck.

Reply to
skybuck2000

I came across this website:

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This is one of the few references to "three-way" I came across my investigation as to why a subwoofer would have three voice coils:

"Crossovers are often described as "two-way" or "three-way""

So my latest hypothesis is that this cambridge subwoofer uses different wattage levels to reach different frequency ranges.

Reply to
skybuck2000

Maybe something like this might work:

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Crutchfield seems to have all kinds of amplifiers... Expensive though...

Reply to
skybuck2000

That sounds very unlikely. Subs with 2 (or in this case 3) voice coils are so that you can drive it from multiple channels at once. Usually just left and right, but modern home theater systems also have a center channel.

Reply to
DemonicTubes

!? What a strange way to achieve that.

Better make sure your channels are all in phase!

--
Cheers, 
Chris.
Reply to
Chris

Dual voice coil speakers are used instead of single, lower impedance, coils. They're driven from two channels of the same amplifier, with the same program material. They're reasonably common in higher-end automotive audio systems.

Reply to
krw

(Small corrections made compared to posting on other newsgroups ;))

My original hypothesis for this three voice coil design is for 7.1 operatio n could be the correct one:

Low Frequencies from Channels is send to the subwoofer's 3 voice coil.

This hypothesis is confirmed by this document stating different magnetic fi elds will result in a net magnetic field describing the action/motion takin g by the subwoofer. So three voice coil would give more precise control ove r waves/cosinus/sinus waves inteferring with each other.

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Since there are only 3 voice coils and 8 signals it would require a mapping for example:

Voice 1: Left+Center+Right Voice 2: Side Left + Side Right Voice 3: Rear Right + Rear Left + LFE

This mapping/hypothesis makes the most since to me.

One other hypothesis is that this company wanted to use the same amplifiers to make production easy.

However this does not cancel out my hypothesis either, this is just a conve nient/bonus.

My guess is that each 70 watt amplifier is being used to cause this mapping effect.

Thus if I would simply wire a single amplifier in parallel to this subwoofe r it would not be the same as wiring three individual amplifiers being driv en with a specially processed or mixed signal.

Knowing creative labs they would probably have jumped upon this oppertunity to use a three voice coil system to it's maximum audio quality potential.

This is probably simply new technology that the mainstream market has not y et catched on too, shown by the simple single pre-amp subwoofer out port.

To duplicate this technology it would require at least 3 pre-amp subwoofer out ports and special signal processing or at least mixing of these input s ignals.

Bye, Skybuck.

Reply to
skybuck2000

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