Powering Cambridge 210w 8ohm Sub woofers

On Thursday, July 27, 2017 at 9:34:09 PM UTC+2, wrote:
On Thursday, July 27, 2017 at 3:07:20 PM UTC+2, Paul wrote:
wrote:
Maybe something like this might work:

https://www.crutchfield.com/p_021AMP....html?tp=48757

Crutchfield seems to have all kinds of amplifiers...

Expensive though...


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

I see a really nice subwoofer:

https://www.crutchfield.com/p_735PSU...00.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

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

http://www.avsforum.com/forum/113-su...-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

wrote:
On Thursday, July 27, 2017 at 3:07:20 PM UTC+2, Paul wrote:
wrote:
Maybe something like this might work:

https://www.crutchfield.com/p_021AMP....html?tp=48757

Crutchfield seems to have all kinds of amplifiers...

Expensive though...

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

I see a really nice subwoofer:

https://www.crutchfield.com/p_735PSU...00.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

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

http://www.stoneaudio.co.uk/?manufac...hnology&page=5

http://www.stoneaudio.co.uk/?product...gy+prosub+1000

Paul

wrote:
On Thursday, July 27, 2017 at 9:34:09 PM UTC+2, wrote:
On Thursday, July 27, 2017 at 3:07:20 PM UTC+2, Paul wrote:
wrote:
Maybe something like this might work:

https://www.crutchfield.com/p_021AMP....html?tp=48757

Crutchfield seems to have all kinds of amplifiers...

Expensive though...

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
I see a really nice subwoofer:

https://www.crutchfield.com/p_735PSU...00.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

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

http://www.avsforum.com/forum/113-su...-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

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

(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/Dual...oilDrivers.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.

On Wed, 26 Jul 2017 02:41:03 -0700 (PDT),
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-xon...nd-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/Categorie...rs/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/Categorie...EQ2496/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.

wrote:
(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/Dual...oilDrivers.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.

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/resour...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

On Tue, 25 Jul 2017 04:38:05 -0400, Paul 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.

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

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 ****. 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.

wrote:
On Tue, 25 Jul 2017 04:38:05 -0400, Paul 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.



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

https://www.parts-express.com/dayton...-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-SAN...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

On Wed, 18 Oct 2017 01:21:27 -0500, 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...ing=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.