Powering Cambridge 210w 8ohm Sub woofers

Hello People,

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

http://www.ecoustics.com/electronics...io/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.

wrote:
Hello People,

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

http://www.ecoustics.com/electronics...io/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.

The sub has three voice coils on it. I've never seen such a thing before.

https://forum.lowyat.net/topic/2873671/all

You can see them repairing the components on the
circuit board there. However, I would guess, come back
in a year or two, and the circuit would be dead again.
(Some kind of glue should be used on those caps, to
give the capacitor the mechanical support it needs in a
high-vibration environment.)

It's not really a good idea to put the amplifier inside the
subwoofer housing. The air temperature is elevated, and no
matter what amp you use, the heat and vibration are
going to damage it.

If originally there was a Class AB amp inside the subwoofer,
it should be replaced with a Class D. A Class AB is 65% efficient,
while a Class D is 90% efficient. The increased efficiency helps
keep the air temperature low, inside the enclosure the amp
is sitting in. If the amp power transistors were on an external
heatsink plate, this would not matter. Since aesthetics are more
important than function, I'm sure the transistors are made to
suffer by living inside the enclosure, in "dead" air (no cooling).

*******

Passive crossover networks, are used inside speaker cabinets
that have a "big" and a "small" speaker. The big speaker is
intended to get the low frequency energy. The small speaker is
intended to get the high frequency energy.

The amplifier used, is broadband and covers both low and high
frequencies.

The circuits shown here, takes that "broad" energy, and sort it
so it goes to the correct speaker inside the cabinet. It's the
combination of a "broad" amplifier, plus "separate" speakers,
that necessitates a passive crossover.

http://celestion.com/speakerworld/do...patech/125.pdf

Now, your subwoofer design is different. One of the signal inputs
to the cabinet, is a "center/sub" 1/8" plug. The "Center" has
a high frequency signal (from the sound card). The sub connection
has a low frequency signal (band limited to 200Hz or lower).
Since the signal has no high frequency component, there is
nothing to steer.

The subwoofer power amp, will similarly be band limited. On
purpose, it's not supposed to reproduced high frequency signals.
So you would never find 20KHz coming from the sub amp board.

Since the 200W of power delivered to the sub, is already at
200Hz or less, there is nothing to filter. Therefore
(as far as I'm concerned), there should be no passive
crossover network inside the subwoofer cabinet.

Your sound card has already separated the high and low
frequency content, on the "Center" and "Sub" signals.

Paul

Hi Paul,

Thanks for your replay.

The repair man writes the following to me:

"Due to the 3 coil design it is not possible to use the speaker on its own".

Do you agree with this ?

Also the repair man claims to fix the units within 4 days ! LOL

The forum guys can take years to fix their own unit.

Repair costs around 200 euros or so, not too shabby !

Still wondering if there are other options.

I also asked him if he "re-glues" the components with some proper glue... cause I also share your "shake" concerns...

The heat... not much can be done about that I guess... or put it in a different enclosure... well if I could get some more years out of this puppy... that'd be nice !

Then again for some money a power subwoofer could almost be bought... twice the money though... which might or might not last longer.

I wonder what's so unique about this subwoofer, is it just a design to make things difficult or does it have some special sound properties ? Perhaps the low frequencies is what it's good at... I pretty much know that cause I tested that once

Bye,
Skybuck.

wrote:
Hi Paul,

Thanks for your replay.

The repair man writes the following to me:

"Due to the 3 coil design it is not possible to use the speaker on its own".

Do you agree with this ?

Also the repair man claims to fix the units within 4 days ! LOL

The forum guys can take years to fix their own unit.

Repair costs around 200 euros or so, not too shabby !

Still wondering if there are other options.

I also asked him if he "re-glues" the components with some proper glue... cause I also share your "shake" concerns...

The heat... not much can be done about that I guess... or put it in a different enclosure... well if I could get some more years out of this puppy... that'd be nice !

Then again for some money a power subwoofer could almost be bought... twice the money though... which might or might not last longer.

I wonder what's so unique about this subwoofer, is it just a design to make things difficult or does it have some special sound properties ? Perhaps the low frequencies is what it's good at... I pretty much know that cause I tested that once

Bye,
Skybuck.


http://www.ecoustics.com/electronics...io/646685.html

"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"

So that's a warning about the thing.

You will not be very happy if you pay 200 euros and it
only lasts a short time.

I think it's a design to make things difficult,
as you suggest.

*******

I've found a couple threads now, which mention trouble
with the sub speaker itself.

https://techreport.com/forums/viewtopic.php?t=73411

*******

Maybe it's better to just look for another sub ?

DIY audio projects don't always turn out well. I've done
a couple little projects that didn't work all that well.

Paul

On Tuesday, July 25, 2017 at 2:53:23 PM UTC+2, Paul wrote:
wrote:
Hi Paul,

Thanks for your replay.

The repair man writes the following to me:

"Due to the 3 coil design it is not possible to use the speaker on its own".

Do you agree with this ?

Also the repair man claims to fix the units within 4 days ! LOL

The forum guys can take years to fix their own unit.

Repair costs around 200 euros or so, not too shabby !

Still wondering if there are other options.

I also asked him if he "re-glues" the components with some proper glue.... cause I also share your "shake" concerns...

The heat... not much can be done about that I guess... or put it in a different enclosure... well if I could get some more years out of this puppy.... that'd be nice !

Then again for some money a power subwoofer could almost be bought... twice the money though... which might or might not last longer.

I wonder what's so unique about this subwoofer, is it just a design to make things difficult or does it have some special sound properties ? Perhaps the low frequencies is what it's good at... I pretty much know that cause I tested that once

Bye,
Skybuck.


http://www.ecoustics.com/electronics...io/646685.html

"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"

So that's a warning about the thing.

You will not be very happy if you pay 200 euros and it
only lasts a short time.

The repair man fixed 200 of these units and claims to have a 2% fail rate.

So that would be 1 every 100 repairs

People fixing these things themselfes run into problems. I think my unit is probably in good shape, only one tiny little thing exploded, but the glue will have to be removed and repair man says it will be replaced with hot melt (only replaced at critical parts), which seems to be safe so far (?)


I think it's a design to make things difficult,
as you suggest.

*******

I've found a couple threads now, which mention trouble
with the sub speaker itself.

https://techreport.com/forums/viewtopic.php?t=73411

*******

This is very rare, have not read anything about other owners with this problem.

Either his subwoofer get damaged because something was under it. Or the noise he is hearing is simply a soundblaster driver issue, which was a known problem with creative labs drivers which has been solved by now. Firefox browser does seem to have audio buffer overruns though which can have the same effect.


Maybe it's better to just look for another sub ?

My fear is that I won't be happy with it. It might sound different.

Meanwhile I am getting confused about this Gigaworks S750 design, so I would first need to figure out what it is actually doing ?

Here is an hypothesis so far:

1. There is a main subwoofer signal which is fed into the subwoofer.

However the gigaworks electronics might be doing something special which I am unsure of if this is real and if for example my receiver can mimic it.

2. The signals ment for the speakers are intercepted by the gigaworks electronics. Everything below 500 hz is re-directed to the subwoofer.

This might explain why the subwoofer has 3 channels.

Here is my hypothesis for the 3 channel design in relation to the 7.1 system:

Main subwoofer signal + Center signal is sent to sub woofer channel 1
Left signal + Right signal is sent to sub woofer channel 2
Back/Rear Left + Back/Rear Right is sent to sub woofer channel 3

This would mean this subwoofer + electronics is capable of playing low herz signals from a 7 speaker set system + main sub woofer signal.

So my fear could be as follows let's suppose hypothesis above is true then buying a simple powered sub woofer might reduce the experience to just 1 channel subwoofer enjoyment/main sub woofer channel, instead of "full surround bass"

Now the big questions a

1. Is the hypothesis correct ? I would need somebody with a working Gigaworks S750 disconnecting all 7 speakers and then playing a subwoofer tone which would go from 1 hz to 500 hz and then see if it was hearable.

Perhaps some special software which repeats this for each of the 7 channels to see what happens to the subwoofer.

Then perhaps repeat this test on a non-gigaworks system to see if the subwoofer behaves the same.

Interesting experiment so far !

My guess would be the hypothesis is slightly incorrect and everything above 100 hz or 200 hz is already cut off and send to the subwoofer... but that might still mean the rest of the hypothesis is correct, just the range is a bit different.

Come to think of it it does seem to make some sense to me.

Games probably simply use 7 channels for surround sound and will output whatever frequencies they please.

The audio system is then responsibly for re-routing this to whatever speakers/woofers are available.

So this might be what the gigaworks is doing...

Now the final big question is:

Could a receiver in this particular case my denon 1909 do this as well ?

Would the denon 1909 be capable of "extracting everything below 100 hz" from the speaker channels and re-route it to the to-be-newly-purchased-powered-subwoofer

Perhaps gigaworks electronics does even more... perhaps it mixes the different low frequency ranges or perhaps not... and just let the subwoofer somehow handle it

DIY audio projects don't always turn out well. I've done
a couple little projects that didn't work all that well.

So far my denon+speakers setup was ok... but I didn't build any electronics.... just found the proper cables for it !

I will have to consult my denon receiver manual... but I doubt this kind of detailed technical thing is in there !

Bye,
Skybuck.

Hmm I see I was a bit sloppy in my hypothesis, so let's try and re-do that to see where problems may occur:

7.1 Surround Sound has 7 speakers and 1 bass unit.

1 Center Left
2 Center
3 Center Right

4 Left
5 Right

6 Rear Left
7 Rear Right

8 Subwoofer/LFE (low frequency effects)

Something like that.

So subwoofer might have 3 channels, now somebody claims that only

Left/Center/Right is re-directed to these subwoofers, but that does make no sense to me.

A mapping that might make more sense to me is:

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

This would make it fully compatible with 5.1 since rear left and rear right would be missing and thus LFE can be used on that voice coil.

For 7.1 rear left and rear right might be mixed together.

Perhaps this is all bull**** and voice coils do not represent channels =D

Bye,
Skybuck.

On Wednesday, July 26, 2017 at 9:52:47 AM UTC+2, wrote:
Hmm I see I was a bit sloppy in my hypothesis, so let's try and re-do that to see where problems may occur:

7.1 Surround Sound has 7 speakers and 1 bass unit.

1 Center Left
2 Center
3 Center Right

4 Left
5 Right

6 Rear Left
7 Rear Right

8 Subwoofer/LFE (low frequency effects)

Something like that.

So subwoofer might have 3 channels, now somebody claims that only

Left/Center/Right is re-directed to these subwoofers, but that does make no sense to me.

A mapping that might make more sense to me is:

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

This would make it fully compatible with 5.1 since rear left and rear right would be missing and thus LFE can be used on that voice coil.

For 7.1 rear left and rear right might be mixed together.

Perhaps this is all bull**** and voice coils do not represent channels =D

Bye,
Skybuck.



This is a little bit interesting:

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

"
Some record labels such as Telarc and Chesky have argued that LFE channels are not needed in a modern digital multichannel entertainment system.[citation needed] They argue that all available channels have a full-frequency range and, as such, there is no need for an LFE in surround music production, because all the frequencies are available in all the main channels. These labels sometimes use the LFE channel to carry a height channel, underlining its redundancy for its original purpose. The label BIS generally uses a 5.0 channel mix.
"

Problem with this could be that leaving out the LFE is not really possible, because games/software might put special signals on the LFE line and thus LFE is required.

Bye,
Skybuck.

On Wednesday, July 26, 2017 at 9:59:54 AM UTC+2, wrote:
On Wednesday, July 26, 2017 at 9:52:47 AM UTC+2, wrote:
Hmm I see I was a bit sloppy in my hypothesis, so let's try and re-do that to see where problems may occur:

7.1 Surround Sound has 7 speakers and 1 bass unit.

1 Center Left
2 Center
3 Center Right

4 Left
5 Right

6 Rear Left
7 Rear Right

8 Subwoofer/LFE (low frequency effects)

Something like that.

So subwoofer might have 3 channels, now somebody claims that only

Left/Center/Right is re-directed to these subwoofers, but that does make no sense to me.

A mapping that might make more sense to me is:

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

This would make it fully compatible with 5.1 since rear left and rear right would be missing and thus LFE can be used on that voice coil.

For 7.1 rear left and rear right might be mixed together.

Perhaps this is all bull**** and voice coils do not represent channels =D

Bye,
Skybuck.



This is a little bit interesting:

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

"
Some record labels such as Telarc and Chesky have argued that LFE channels are not needed in a modern digital multichannel entertainment system.[citation needed] They argue that all available channels have a full-frequency range and, as such, there is no need for an LFE in surround music production, because all the frequencies are available in all the main channels. These labels sometimes use the LFE channel to carry a height channel, underlining its redundancy for its original purpose. The label BIS generally uses a 5.0 channel mix.
"

Problem with this could be that leaving out the LFE is not really possible, because games/software might put special signals on the LFE line and thus LFE is required.

Bye,
Skybuck.

This is also a little bit interesting:

https://www.dolby.com/uploadedFiles/...nal/38_LFE.pdf

Basically it explains the LFE signal can carry some more information for movies and such.

Now back to the topic of this mysterious three voice coil subwoofer !

First question is what the hell is a voice coil actually ?

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

Didn't read all of it yet but here goes:

It seems to be some wiring in loops/circles which cause some magnetic field..

The wave audio/form is run through this coil which then causes the magnetic field which eventually causes the whole thing/membrane or whatever to do it's thing and produce a sound wave.

So I suspect this three-voice-coil subwoofer, uses three of these rings and thus it uses three magnetic fields which will probably mix themselfes into one magnetic field or something, or maybe just three and somehow it warps the membrane a bit different then subwoofers which have just one or two.

So that might be the secret behind this subwoofer why it may sound better than others... or perhaps it's just a cheap way to mix three different channels together.

Not sure what happens to magnetic fields when they overlap, do they become one ? or do they stay seperate ?!

Bye,
Skybuck.

I checked manual of denon 1909 av receiver.

It has MultEQ functionality which works with a little mic which came with it, it detects speaker/sub woofers and it will calculate cross over frequencies automatically and compensates for any room distortions and such.

And it probably even has a manual cross-over setting as well if so desired, can vaguely remember that... yeah lol... it's possible to display the menu on an LCD monitor via analog/crt signal or something with a cable. Or just use it's own LCD display.

So buying non-creative labs speakers and subwoofers should work just fine with the creative x-fi elite pro soundblaster... so I don't think that will be a problem.

So maybe Gigaworks S750 doesn't do anything too special.

The question remains though if I have to buy a completely new subwoofer which could set my back 500 euros if I want a good one or something, maybe there are cheaper ones.

Or if I only have to buy some amplifiers and then power up this weird tripple voice coil thing

Or have the gigaworks S750 fixed/repaired, which is the most risky investment for safety and longevity/duration. Though then I do get what I was used too which basically was superb sound ! LOL. Plus I get to experiment and compare the gigaworks to the denon receiver to see if there is any sound quality difference, for speakers I would guess not, bass I would not really be able to test and probably depends more on the subwoofer than anything else. I do known that cheaper pc speaker systems give horrible bass sound. More expensive subwoofers can be boomy... or just not my liking so that is somewhat questionable, maybe they be better or maybe they be worse, this is also somewhat uncertain if I go for option 1.

Option 1 has uncertainy of bass quality.
Option 2 might not be possible, or might leave me with an open subwoofer.
Option 3 might eventually break/die again, has heat issues, glue issues safety issues, but probably still best bass quality.

The tripple voice coil design remains a mystery for now, it might have to do with the ammount of power it can handle, which apperently is 210 watts.

So perhaps a replacement subwoofer would need to be 210 watts.

Adventage of option 3 is functioning bass/volume controller of speaker system on my table, which is kinda nice, option 1 could come with some kind of ****ty wireless control or no control... little bit nasty then again bass can also be done via software equalizer, which is what I now do sometimes for games.

For now the mystery of the tripple voice coil attracts me ! LOL. First I want to clear that up... but maybe it will never be unraffled as to it's secrets !

Question now is if there is a good subwoofer with 210 watts of power and low hz.

However I did find the gigaworks to also be a bit boomy... I don't like bass that much... but it was nice and warm... so definetly want that back for nice sniper shots, artillery shots and music.

I am thinking of maybe trying out a cheap/simple bass unit first to see how that works out... or maybe borrow one or something... maybe one person can help with that not sure... probably not though.

I heard some subwoofers in stores and some systems... didn't really like them that much... that s a bit of the problem... none seem to come anywhere near the gigaworks... but perhaps I judge it wrongly... hmmmm... I'd love to test them though... hihi... love testing but can't do that or can I ?

For that option 3 would need to be chosen first... first a fix... and then maybe later I can still buy new gear to see if there is anything better out there...

Money is not really the main concern... safety is main concern for me and my PC actually too... repairman said it's not too risky.

I don't wanna get scammed though... or end up with a dead unit two or three months later and then be down 200 euros for nothing... well at least I freshened up my memory of how gigaworks sounded...

Ofcourse with a repaired unit I can never be sure if it sounds like it originaly did... though maybe I can tell

I wonder if maybe repair man will take out special stuff and sell it lol. like the subwoofer itself and replace it with a cheaper one lol. I may check that though

As far as I can remember I have never gone down the "repairman" route myself... hmmmm...

Perhaps the opposite might also happen maybe denon receiver sounds even better for satelites than gigaworks... that would amaze me

Option 2 has the drawback of having to place an extra box somewhere if it were to be a box... with a plate amp... less of a problem.

Option 3 has the risk of other white glue turn brown and cause additional problems... this is very risky and dangerous I think... this is putting me off.

So this is why I would want a combination of option 2 and 3 if possible.

Salvage the subwoofer and wooden enclosure and such, throughout the unsafe electronics.

Hmmmmmm....