Powering Cambridge 210w 8ohm Sub woofers

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skybu...@hotmail.com

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Jul 25, 2017, 2:35:51 AM7/25/17
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Hello People,

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

http://www.ecoustics.com/electronics/forum/home-audio/646685.html

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

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

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

Perhaps the best option is a "plate amp". Apperently this is some kind of plate 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 dimensions.

For now this is an experiment mostly to see if it would work, if it is possible 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 Gigaworks 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 amp 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 duplicate 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 the amp plate might be a good solution for this gigaworks if it happens to have 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 because my experience with "amplifiers" is zero.

I do own a denon receiver 1909 which is used to power the 7 satelitte speakers 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 damaged it and the designs looks kinda shady ! ;) :) but perhaps I am a bit to untrusty of that :) also I like to give other electronics a try just to see 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.

skybu...@hotmail.com

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Jul 26, 2017, 9:48:30 PM7/26/17
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I have some data sheets available about this device on my webdrive located here:

http://www.skybuck.org/GigaWorksS750/

(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:

http://www.tgahinfo.homecall.co.uk/S750%20PSU/

Bye,
Skybuck.

skybu...@hotmail.com

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Jul 27, 2017, 7:01:40 AM7/27/17
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I came across this website:

https://en.wikipedia.org/wiki/Audio_crossover

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.

skybu...@hotmail.com

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Jul 27, 2017, 7:44:43 AM7/27/17
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Maybe something like this might work:

https://www.crutchfield.com/p_021AMP1200/AudioSource-AMP1200VS.html?tp=48757

Crutchfield seems to have all kinds of amplifiers...

Expensive though...

skybu...@hotmail.com

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Jul 28, 2017, 2:06:51 AM7/28/17
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(Small corrections made compared to posting on other newsgroups ;))

My original hypothesis for this three voice coil design is for 7.1 operation 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 fields will result in a net magnetic field describing the action/motion taking by the subwoofer. So three voice coil would give more precise control over waves/cosinus/sinus waves inteferring with each other.

http://www.adireaudio.com/Files/DualVoiceCoilDrivers.pdf

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 convenient/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 subwoofer it would not be the same as wiring three individual amplifiers being driven 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 yet 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 signals.

Bye,
Skybuck.
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