Powering Cambridge 210w 8ohm Sub woofers

[skybu...@hotmail.com]

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.

[Paul]

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/downloads/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

[skybu...@hotmail.com]

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.

[Paul]

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

[skybu...@hotmail.com]

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 are:

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.

[skybu...@hotmail.com]

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 bullshit and voice coils do not represent channels =D

Bye,
Skybuck.

[skybu...@hotmail.com]

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.

[skybu...@hotmail.com]

This is also a little bit interesting:

https://www.dolby.com/uploadedFiles/Assets/US/Doc/Professional/38_LFE.pdf

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

[skybu...@hotmail.com]

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.

[skybu...@hotmail.com]

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 shitty 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....

[Paul]

The Gigaworks has a "decoding" function, so there is at
least one input which is high-tech in nature. Your manual
probably shows what that is for. There is a smaller box
I think, that has the decoder in it.

It should also have regular 1/8" analog connections. Creative
either uses TRS or TRRS plugs. TRRS has four contacts total,
three analog signals plus ground on S. The only reason Creative
would use TRRS, is if the unit was intended for sale with
a Creative sound card (which comes with that kind of cabling
and connectors).

So the unit should look something like this. If I had a manual,
I could draw a better picture.

Some_kind_of_digital_signal --- decoder_box -----------+
7.1 decode --------+ |
-----+ | |
--+ | | |
+---------- two_amps --- two_speakers
(7.1 Inputs) | +---------- two_amps --- two_speakers
Analog_Stereo --------------------------------+ | +---------- two_amps --- two_speakers
Analog_Stereo -----------------------------------+ | +--------- center ----- speaker
Analog_Stereo --------------------------------------+ +--------- 210W amp --- sub
Analog_Stereo -----------------------------------------+

To me, driving the three coils in parallel, and using a
single 210W amp makes the most sense. I don't know what
happens when three 70W amps drive three coils in close
proximity, especially if there is a slight phase
difference between amps. There could be transformer
action between coils. When the coils are operated in
parallel, that doesn't matter.

I don't see how the repairman can guarantee years of trouble
free function, when the design appears to have a high
failure rate. The repair thread I was reading, no "correction"
is being made to the circuit. Using a 105C cap in place of an
85C cap, doesn't make your problems go away. The unit is
likely to be getting too hot - the combination of no
airflow for cooling, plus the extreme total amplifier power.
If a Class AB amp is 65% efficient, the place where the amplifiers
is located, is going to get hot. If they were Class D amps
of 90% efficiency, that might be enough to control the heating
issue. But even the back of the sub speaker itself probably
gets a bit warm.

And so far, I haven't seen a functional description of the thing,
or found a schematic. So I don't have much to go on. But there seem
to be lots of discussions about repairing them.

Paul

[skybu...@hotmail.com]

Hi

I have had schematics on my webdrive for a long time though, fortunately they still there, I also some some links on some forum, perhaps they were updated, perhaps not.

But for what it's worth take a look at this:

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

There is a rar file, I hope you know and can open rars files ? ;)

I will see if I can find some more stuff for you to look at.

Euhm oh yeah I read somewhere these are supposed to be class D amps ? but maybe I read that somewhere else not related to gigaworks can't remember. I think they were though.

And I share your oppinion... storing 700 watts of power into a little box seems pretty crazy ! :)

Also storing electronics inside the subwoofer seems pretty crazy too ! :P :)

So perhaps "passive subwoofer" plus "amplifier" at a distance is safest and best option for me ! ;) :)

Turning this subwoofer into a passive subwoofer would be cool =D

Bye,
Skybuck.

[skybu...@hotmail.com]

Here some more info available, wasn't too hard to fin

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

Not sure if the gigaworks manual would be usefull it probably contains limited information, I have a paper copy of it though.

Anything specific you would want to know about it ? ;)

[skybu...@hotmail.com]

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.

[Paul]

So one "project" apparently, was to move the Gigaworks S750
electronics into a separate box. A box with fan cooling...
On that web page, you might be seeing some schematics
for the fan control of the "modified" Gigaworks. Whereas
the power supply components are related to the product itself.

The BASH amplifier, is apparently a combination of a Class D
and a Class A/B. It sounds like the Class D produces a rail
voltage for the Class A/B, such that the Class A/B barely has
enough voltage to reproduce the signal. And, in doing so,
the efficiency of the A/B is improved. It *sounds* like a
way of making a linear amplifier, but with power rails
that track the output level required. This description isn't
all that clear, so this is just my interpretation of it.

http://www.psaudio.com/pauls-posts/bashing-amps/

The BASH amp in the S750 is describes in an ST Micro datasheet.
It's the STA575 amp, in hybrid (plate) format. This won't be
quite as efficient as a pure Class D, but it doesn't need a
reconstruction power filter on output. The module is more efficient
than a Class AB with fixed power rails. I would guess this is
still a "thermal disaster" in terms of heating the Sub enclosure.

https://www.scribd.com/document/29015097/Bash-Sta575-creative-gigaworks-s750

http://www.st.com/content/ccc/resource/technical/document/datasheet/34/2b/27/68/e9/62/4b/6d/CD00002481.pdf/files/CD00002481.pdf/jcr:content/translations/en.CD00002481.pdf

It's a stereo 100W+100W module, but is limited to 75W per channel,
because the THD is so low at that power level. That's where the
power rating of the product comes from. They don't want to run
the amp, such that the THD is going to be 10% or whatever. The
power is delivered at a level where there is low total harmonic
distortion.

So I could understand, if you found five of those modules inside
the enclosure. That would be seven channels for the satellites, and
three channels to drive the speaker coils. The speaker coil design
was probably dictated by the nature of the "canned" amplifier design.
(Make all the amplifiers the same, no matter what.) Maybe ST Micro
did the design for them ?

Paul

[skybu...@hotmail.com]

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]

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...

[Paul]

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

"three-way"... the crossover splits a given signal into three frequency ranges.

Amp_Output -------- Crossover ------ tweeter
------ midrange
------ woofer

This speaker would use a "three-way".

http://salestores.com/stores/images/images_747/SHF41LR.jpg

*******

The Sub speaker has three coils, for reasons other than speaker
design. I think they wanted to use the same BASH amplifier
for everything, and that's why the speaker ended up
designed that way.

I saw a picture today of the back of the Sub enclosure, and it does
have a heatsink. I presume the BASH amplified are tied into
the heatsink. And so maybe just the power supply components
located inside, are taking most of the thermal abuse.

Paul

[Paul]

That's what I notice too. Audio was always
like that, and every time you go back to the
market and look for product... you'll be disappointed.

Drop into a local stereo/TV/HomeTheater store and
listen to some systems there. You won't buy anything
on your first trip, but you will get some idea
how expensive the stuff will be.

Paul

[skybu...@hotmail.com]

Today I had the gigaworks taken out and I saw the little bugger after many years... it looks so cute ! The electronics is much tinier than I remember.

The pictures make it look so big ! ;)

Or maybe my eyes deformed.. or it's my glasses ! ;) :)

Anyway... shipping it to repairman will be an undertaking.

In the past I already communicated with him. Back then he wanted me to disassemble the thing into seperate boards and mail it.

I just realized a moment ago.

I was planning on sending the entire thing to him. Not sure if he will accept it like that.

I don't want to disassembly it cause I am not sure I will get it back together... it would probably require a glue gun.

Meanwhile I have seen some nice subwoofers at that website... then my Pal came... who is helping me with this hihi... and I had to stop my investigations into that.

I kinda want to attempt it to get it fixed, but it depends on the repair pal and his terms for "service" ;) :)

Also I would have to couple my bank account to "pay pal"... hmmm which might put my bank account at risk... not sure about that... will have to investigate that further...

Different paying options would be nice. For now I will have to wait till repair man gets back to me... and next week if the "repair" project goes further I will try find some more boxes and filling material.

Or maybe I will get fed up with it and just go for a new sub... but what if I don't like the sound of the new sub ! HA !

I can always buy a new one later...

Also it might be interesting to have two systems... since I will have to full blown PCs soon... not sure yet if I want two surround systems or some kind of mixture... or perhaps sub can be re-used with older speakers...

However my PC and this system kinda belongs together... then again maybe not... depends on how you look at it...

The signal to nose ratio of the entire thing is according to manual 99. Which isn't too high... maybe there are better systems out there... so far I am liking the speakers though.

I did plug the bugger back in... and powered it up... the light briefly blinked... so it didn't magically come back alive...

Further concerns are: What if the chemical compounds inside the caps already dried up ?! :) It's been in a somewhat hot room for many years now... 25 degree celcius or so sometimes... hmmm though stuffed away behind boxes and so... maybe it was well isolated because of those carton boxes that would be funny ! ;)

And it does have a heatsink ! <G> ! ;) :)

Mailing costs will be something like 25 to 35 euros for the cabinat and such... bit expensive but I am willing to pay that... question is what will repair man do when he has to sent it back ? Might be a problem for him... hmmmm...

This might be a deal breaker :)

Or I would need to get some glue gun skills ! LOL.

Taking it apart could cut back on some mailing costs though... but this would be replaced by having to buy a glue gun and perhaps getting my fingers burned ! ;) :)

Not sure if I can get the thing back into as it was hmmmm... he did send a rar back then... gonna examine that closer.

Good communication with repair man is very important though... I learned that from this little excersize... many things could be overlooked and many miss understanding could occur.

Fortunately I still have the cables for the entire thing and controller which is probably necessary to get the device to go from standby into operational condition.

My "pal" did drop the controller on the floor... not sure if it's not damaged... probably not... but it would suck if it was... hmmmm...

He did notice something interesting though... creative only requires 1 plug per speaker instead of two... because of the plugs design... that was kinda interesting ! ;)

Fortunately I also had the screws to screw the back plate back on... cause I just let it loose without the screws in... I have screwed the thing back together...

Fortunately I also kept a picture of where each screw went cause they have different lengths...

So for now "lady-luck/fortune" is on my side... but how long will the luck continue ?! LOL.

Can you feel the excitement ?! LOL.

Am I crazy ? For trying to repair this bugger ?! LOL.

Oh man... only time will tell ! ;)

Sigh,
Bye,
Skybuck.

[skybu...@hotmail.com]

I see a really nice subwoofer:

https://www.crutchfield.com/p_735PSUB1KB/Definitive-Technology-ProSub-1000.html?tp=187

=D

Unfortunately their distribution is only in US :(

I wonder if I can get this stuff in Europe somehow ?! ;) =D

Bye,
Skybuck =D

[skybu...@hotmail.com]

Wow the specs look awesome, but the reality is different:

http://www.avsforum.com/forum/113-subwoofers-bass-transducers/1271997-definitive-technology-prosub-1000-rattling.html

Seems like the legs are causing this puppy to rattle ! ;)

Hmmm this just proves again... finding really *good* gear is hard ! =D LOL.

Bye,
Skybuck ;)

[Paul]

If you could move the components outside of the original
sub enclosure, then you wouldn't need to glue everything.

The glue is there, because the electrolytic caps are in
a high-vibration environment. The caps are glued to one another,
or glued to the PCB, to physically secure them. In the repair pictures
where the caps are "floating in space", such a mounting won't
last forever.

In terms of disassembling things and reassembling them, take pictures.

Use your digital camera, or web cam, each step of the way. Even
if you cannot re-assembly it later, you can take the pictures to
a local repair shop, plus the pile of boards, and they can use
the pictures to do the re-assembly. You want to record the polarity
of the wires. Ideally, you want pictures to show the polarity of
the capacitors too. The electrolytics have a plus and minus on them,
and to prevent them from exploding, an assembler is required to check
each one visually, to make sure it's in the right way. On some assembly
lines, you'll see a wax pencil mark on all the components that have
been verified for correct insertion. If your repair man accepts
just the individual boards, he may not have tested the repair,
and functionally verified all the caps are inserted the right way.

That's to give you some idea of the level of detail I'd want in the
photos I was taking. I want the photos to be a "reference" for
when the repaired boards come back.

But I'm not really encouraging this repair operation ("re-capping"),
unless there is a solution for the thermal situation. As long as
the inside of the Sub gets good and hot, the repair will not
last very long. If the glue is degrading in the heat, that's
not a good sign. And, in the threads of discussion, to find out
that the glue conducts electricity (is not high voltage compatible),
well, what were they thinking ? Even a hot glue gun, I don't know
right off hand, what kind of dielectric properties it has, and
whether you can use it just anywhere. The manufacturer could have
used hot glue too, except the hot glue would likely get
soft at high air temperatures (inside the Sub).

Once the electronics are moved to a separate, well ventilated
cabinet of some sort, then the glue isn't necessary. (The
separate cabinet would not have nearly the same level of
vibration.) And the glue can be cleaned off, at least where it
touches high-voltage points in the circuit. If the glue is sitting
on the plastic sleeve of the capacitor, that doesn't hurt anything.
If the glue causes one of the 470u caps to arc over (glue touches
the solder pads maybe), well, that's not a good thing.

Paul

[Paul]

I see a seller here, but no price is visible in my browser.

http://www.stoneaudio.co.uk/?manufacturer=definitive+technology&page=5

http://www.stoneaudio.co.uk/?product=definitive+technology+prosub+1000

Paul

[Paul]

Particle wood board and wood screws. Quality.

Just about everything is like that.

*******

A guy at work, build his own subs. He insisted that a left
and right sub were necessary (he built them, before anyone
could talk him out of it). He bought raw sub speakers 36" in diameter.
And built cabinets himself. In the bottom of the cabinet is a
large amount of weight (sand ballast). This keeps the units on
the floor when used (no rattle, no skating across the floor).
And yes, they're loud. They can shake the walls. He's in a townhouse,
with neighbors next door :-) The subs are tall enough, you
can rest your beer bottle on them while standing next to them.
They happen to be front-firing, as making them bottom-firing
would have wasted too much living room floor space.

That's how you get to control the materials put in a sub. DIY.

Paul

[skybu...@hotmail.com]

(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.

[Flasherly]

On Wed, 26 Jul 2017 02:41:03 -0700 (PDT), skybu...@hotmail.com
wrote:

creative x-fi elite pro soundblaster... so I don't think that will be
a problem.

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.

-
I sort of favor ASUS soundboards, although this isn't their most
expensive, I suppose being how you look at it for the cost of
replacing (and keeping possible sets of spare) OPAMPs for individual
characteristics in an array of possible sonic arrangements. In that
regard, it's a twirly-bird, or roll-your-own board:

https://www.bursonaudio.com/asus-xonar-essence-stx-upgraded-with-supreme-sound-v5-op-amps/

I also like bass, or rather than like, it's important to guitars I
play: although six-strings, one is strung heavy with a bass
arrangement, (sic) a baritone guitar that does bass below the 5th fret
and melds somewhat with regular-gauge guitars above that. And, true,
bass is about power -- hearing it, as I do, or rather lacking it at a
conservative 120-watts (viz a quartet of EL34 vacuum tubes). A better
reference to actual bassists, from 15" speakers, or more, running at
something along 400-watts presence. Less lacking from my speaker
arrangement, a closed system 4x12" "half-stack", (changed from stock
for my own speaker brand/placements), which is up to 600watts
handling. Very bass efficient. The other guitar is a solid-body
nylon, Canadian make, with unusually efficient and pleasant bass
tonality.

Getting into these sorts of things, especially from an instrumental
vantage, options of course widen. But as you've already mentioned
consideration for discrete components, external amp/s, that places you
closer into a "real world" of how these things are conducted.

I've two amps, btw, for close to 400watts combined, (peak, although
with comfortable RMS values in line with respectable gear), both high
quality and full-spectrum fidelity, in disallowing several vacuum
instrument amps, I prefer to pair by instruments for odd harmonics,
over of course solidstate.

What, I'd questionably if not tediously resisted over some time,
before awakening one day, was a mixer board. Indispensable to at
least recordings -- along with a convenience given newer USB mixers,
nor should they be overlooked from an external standpoint of
processing through Fx chains. Not all effects need be so "special"
when about basic EQ-ing or compression/expansion, eg the art of
"power" management. And so on and so forth on down and all along the
chain...a recording production is, after all, another derivative and
viewpoint from someone otherwise handing it to you on a platter.

My Behringer mixer, after looking over options for replacement, no
longer makes sense to me. What's reasonable doesn't fit into a value
for delivered. What I like that makes sense is their $2000/US premier
model...

http://www.music-group.com/Categories/Behringer/Mixers/Digital-Mixers/X32/p/P0ASF

Then again, German engineering from Behringer has screwed me over once
before, with a DSP/ADC processing unit, that premiered to "take the
world by storm" - for $450/US when it first came out;- being that
there was significance, however, perhaps like your Cambridge setup, in
a poorly designed power supply unit, among failure reports which later
surfaced, to include mine.

http://www.music-group.com/Categories/Behringer/Signal-Processors/Equalizers/DEQ2496/p/P0146

Pedantic elements abounding, no doubt, when creating perfect sound,
although I wouldn't worry too much about a least amount of money spent
over perfectly acceptable derivatives. (Both my studio speakers pairs
I found for a quarter their value: 1) phased-out, new/old-stock models
at the end of year, and 2) store models with limited usage from
controlled demonstrations.) Passive bass drivers, btw, "skins" like
on drumheads, from the back of closed enclosures, for radiating from
against the walls. East Coast, or Bostonian sound design engineering,
as opposed to West Coast, ported for the bass response from speaker
enclosures. A reasonably tight facsimile for a drum snap for being
derived by two midrange, driven arrays in diametric opposition.

[Paul]

Well, there's no block diagram provided by Gigaworks.

The composition of modules used in the Sub box construction
would help confirm how it is designed.

The application notes, don't address building a Sub amplifier and
they tend to focus on the satellite speakers.

http://www.st.com/content/ccc/resource/technical/document/datasheet/34/2b/27/68/e9/62/4b/6d/CD00002481.pdf/files/CD00002481.pdf/jcr:content/translations/en.CD00002481.pdf

The design only appears to be "approximately" BASH, in the sense
that each amplifier module is just Class AB, while the buck converter
power supply is effectively a shared Class D. the buck converter
adjusts the applied voltage to the amplifier modules, according
the the "loudest" channel. The voltage used might be too much for
the quieter channels, and so they get a little warmer than they
need to. (The purpose of making the power rails track the output
voltage, is to make the amp more efficient.)

I tried to find any kind of info about the STPB01 digital feedback
circuit (which presumably drives the buck converter), but I can't
find a datasheet for that one.

It would appear to me, that ST Micro wanted to sell amplifier
circuit boards, as they have sample designs available like that.
But whether that's what Creative used, you'd have to judge by
looking at the guts to figure that out.

*******

The three coils in the sub speaker are going to be
coaxial. And all they can do, is work together,
or work against one another. I don't think the
design is one of those fancy ideas where the shape of
the woofer cone is controlled by feedback, to make it
"stiffer" or something. It's just a power sharing idea
in this case.

It could involve three coils of different diameter,
working on a magnet which consists of concentric cylinders
of material, but that's really pretty unlikely. The speaker
has no wires for feedback or anything.

The articles I can find on dual voice coil speakers, simply
treat the issue as a means of adjusting load impedance. Like
operating two 8 ohm dual coils in parallel as a 4 ohm load.
Operating the coils in series to make a 16 ohm load would
be silly, as the supply voltage on the amp must be increased,
to achieve the same power level.

In modern terms, it's the kind of thing you'd drive all
three coils in parallel as a 2.67 ohm load. But then you
need to design a 210W amp to reach the same target power
level.

Since the "approximate BASH" design they're building, uses
a shared buck converter, it's to their advantage to make
ten identical 70W amplifiers, and use three of them to drive
the sub. The same shared buck voltage can be fed to all the
amplifiers in parallel. If they made a separate 210W amplifier,
it might need a different operating voltage.

To make the design precisely BASH, would require a buck converter
per channel, which would make the design more expensive in terms
of parts cost and size. But then the channels and overall unit,
would be more efficient, and the inside of the sub wouldn't
heat up quite as much.

Paul

[anon...@internet.none]

On Tue, 25 Jul 2017 04:38:05 -0400, Paul <nos...@needed.invalid> wrote:

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

Same here. I am into audio equipment and I never heard of any speaker
having more than one voice coil. Actually, I'd think that having 2 or
more voice coils would cause distortion, since one coil would work
against another coil, unless everything was 100% precise in signal power
and tone. I cant see that ever happening.

Also, there was the mention of a "plate amp". What the heck is that? All
I can think is that it means a vacuum tube amplifier, which produces
it's power from the PLATES inside the audio tubes.

[anon...@internet.none]

Too much electronics can ruin the real sound of music and this sounds
like one of those cases. You dont need all those channels. My stereo is
made from a 600W commercial power amp, with left and right channel
feeding a pair of quality commercial speakers (made for live
performers).

It kicks ass.... I dont need all that excess stuff.

I know a local band, who are really good. They have their own sound
system, which is similar to my stereo, except they have a large 24
channel mixer board on the front end, and have a little larger power
amp. They always have really good sound. But last summer they played at
a festival where the sound was provided by a sound company. That company
had racks and racks of amps and effects boxes, had 3 mixer boards with a
total of somewhere around 150 channels, they had speakers all over the
place, so much the view of the band was partly blocked. Controlling that
mess were four guys, each with a laptop computer connected to the sound
system, and there were several more computers in that mass of
electronics and tons of wires.

The show started late because the sound guys were having technical
problems. When they finally got all that stuff working, the sound was
muddy, sounded fake, and made the band sound like shit. Sure, they had
enough power to lift the roof off the open sided "barn" they played in,
but it was not quality sound.

About all that sound company did was run up a huge electric bill for the
venue, while irritating people living within 3 miles of that stage, if
they were not at the show.

Live bands always perform with a Left and Right channel sound system. If
you want your home stereo to sound like the original live concert, then
you dont want or need 7 channels.

I do have to admit, that I have a 3rd channel on my stereo. It's both
Left and Right channels combined, fed thru a delay unit, a small power
amp and a 3rd speaker placed in the rear. What that gives me, is the
echo you usually hear in a large hall, which makes the music sound
"live". I dont always turn that on, it just depends on what I am
listening to.

One other thing. What kind of music are you inputting into all that
gear? If it's MP3 files, you already have crappy sound quality. Yea, I
use MP3s too, but if I want QUALITY I listen to vinyl records, followed
up by Cds, or reel to reel tapes. Vinyl is preferred as long as the
records are in good shape. I've kind of given up on the reel to reel
tapes since it's too hard to obtain tape anymore. Cds are digital, so
they will never sound as good as vinyl, but they are still superior to
MP3s.

[Paul]

"Plate" refers to the form factor. The definition is pretty loose.

https://www.parts-express.com/dayton-audio-mcwa60-60w-class-d-full-range-20-plate-amplifier-with-wi-fi-and-bluetooth-40-a--300-780

A lot if them seem to be Class D. On many of them, the "face"
has a big heatsink.

*******

Now this to me, was the canonical plate amp.

They used to make hybrids. It's basically a differential
amp, with hand-picked (matched) transistors. Some of
these had damn good THD figures. The Japanese had a
lock on this market. Then the Chinese started making
counterfeit versions, that didn't have exactly the
same performance. There is one web site that keeps
track of electronic counterfeiting, and one company
that makes consumer stereo, got "stuck" with an order for 10,000
of the fake ones. Well, what do you do with them ?
The good ones used to cost as much as $150 a unit
(because of their specs). They weren't high power,
but they could have low THD at decent power.

It's obvious this one is a bit on the cheap side. Sometimes
you can tell what's going on, if the unit has been out
of production for 20 years, and they're still selling them.

https://www.ebay.com/p/STK4141II-SANYO-Audio-Amplifier-Single-Hybrid-SIP-15pin-NOS/1100256062

My old amp had a SIP module like that in it. Mine wasn't
all that good though. (I didn't buy the amp, a next
door neighbor gave me his.)

*******

Skybuck's 7.1 system is B.A.S.H. based.

That's a PWM SMPS producing a rapidly varying DC voltage.

Each amplifier channel is Class AB.

The controller checks all the channels, and adjusts the SMPS
so a voltage is available which is slightly higher than the
needs of all the amplifier channels. Say the Left speaker
needs 20 volts, the PWM thing produces 23 volts. The Class AB
amplifier, the upper transistor is almost fully on (saturated),
so the voltage drop across it is minimal. The Class AB amp
runs cool. And SMPS power supplies run relatively cool too.

Well, what sin did they commit with Skybucks amp ? They
put it in a Sub enclosure, with no air circulation.

The B.A.S.H. amp could be even more efficient, if each
channel had its own tracking power supply. Then, every
channel would have the same kind of efficiency. If just
the loudest channel is "carefully" adjusted, the other
channels have their transistors in the linear region,
so their output transistors get hotter. But it would
cost too much money to have a B.A.S.H. controller plus
a SMPS per channel.

In the Skybuck amp, there are ten channels. Three channels
run the sub, to the three sub voice coil windings. Seven channels
run the satellites. All the channels operate off the same
voltage (so only one SMPS is needed).

If you instead wanted to use a sub with one voice coil
winding, you could easily design a 210W "larger" amp to
run the sub. But, you'd need to install a second SMPS,
as the voltage this 210W amp needs, would be higher than
the voltage used by the 70W amps. I guess they compared
the cost of having a sub custom-made, versus the cost
of extra electronics to run the B.A.S.H. to the sub
with a different set of conditions.

This one is *not* the one Skybuck has, but the
documentation is pretty clean, and the design is
easier to look at. This design isn't inside the
sub, so it doesn't need that conductive glue all
over the place.

http://www.thompdale.com/bash_amplifier/bash_amp.htm

Paul

[Flasherly]

On Wed, 18 Oct 2017 01:21:27 -0500, anon...@internet.none wrote:

>One other thing. What kind of music are you inputting into all that
>gear? If it's MP3 files, you already have crappy sound quality. Yea, I
>use MP3s too, but if I want QUALITY I listen to vinyl records, followed
>up by Cds, or reel to reel tapes. Vinyl is preferred as long as the
>records are in good shape. I've kind of given up on the reel to reel
>tapes since it's too hard to obtain tape anymore. Cds are digital, so
>they will never sound as good as vinyl, but they are still superior to
>MP3s.

Too broad and narrow.

These Klipsch Kornwall series,

https://www.amazon.com/dp/B000PT94V2/ref=twister_B00TO4XLTA?_encoding=UTF8&psc=1

were discounted a few weeks ago, from a NY web distributor;- when I
got there, the link was broken, apparently disconnected, on a $1000
sale for a pair of $5000 speakers. God help me, were it otherwise.

I've mixed monitors - not bi-amping, but signal-splits variously
through hard and software, including dynamic hardware excitation. A
mixer serves the sum outputs, two discrete output then provide two
amplifiers. Good speakers, withstanding, although not in a grouping of
Klipsch flagship series;- the last were chosen for an auxiliary
standpoint of an engineer's standpoint and experience in the sound
mixing/recording environ;- an intimacy of "140-watt" nearfields.

Speakers tend broadly to compress dynamics. I've also worked with
stage speakers and players used to performing through them;- as well
as having substituted my own for that purpose, a successful adaptation
for monitoring and mixing the live performance (outside of initially
laying the tracks through headphones for monitoring microphones).

The Klipsch are at variance from average expectancies. High
efficiency, for a relative low wattage of uncompromising fidelity
across transparent dynamics -- a somewhat different approach we used;-
Lots of reverb and sustain for filling the sound stage;- Helpful to
prolong sessions from burning out the singer's vocal chords from
repeated overdubs.

Not exactly from an orchestral pit, and dynamics possible from a
surrounding acoustic allowances within a metropolitan centre
institute, one built hundreds of years ago.

Then again, the Klipsch initially gained their advertising stage from
an early "amplified" presidential speech;- the prototype construction
gained enough notoriety to launch them into the votary of
manufactured musical reproduction.