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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Subwoofer Forum => Topic started by: MIKE Lynn on September 22, 2017, 04:12:12 pm

Title: PK Sound Gravity 30 Subwoofer
Post by: MIKE Lynn on September 22, 2017, 04:12:12 pm
  So anyone have any thoughts on this beast ? Im always checking out Subs and came upon this one. I haven't heard of the Company but that dont mean anything.

http://www.pksound.ca/products/gravity-30/

 I Also know DAS http://www.dasaudio.com/en/p/sf-30a-2/ uses the same powersoft 30 in a box they built for club install , and Rat sound http://ratsound.com/daveswordpress/2017/01/08/american-bus/  makes a box with it also.
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Tim McCulloch on September 22, 2017, 04:16:05 pm
  So anyone have any thoughts on this beast ? Im always checking out Subs and came upon this one. I haven't heard of the Company but that dont mean anything.

http://www.pksound.ca/products/gravity-30/

 I Also know DAS http://www.dasaudio.com/en/p/sf-30a-2/ uses the same powersoft 30 in a box they built for club install , and Rat sound http://ratsound.com/daveswordpress/2017/01/08/american-bus/  makes a box with it also.

PK is one of the darlings of the EDM circuit.
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: MIKE Lynn on September 22, 2017, 04:20:22 pm
PK is one of the darlings of the EDM circuit.

 Yeah I read that about them , How do the compare to most other commonly use subs in the industry ? Are there alot of riders calling for them in the EDM world ? Most of the EDM show systems I have seen use a ton of dual 18 boxes (matching the tops Brand Name )  in cardiod configuration.
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Art Welter on September 22, 2017, 05:02:23 pm

1)How do the compare to most other commonly use subs in the industry ?
2)Are there alot of riders calling for them in the EDM world ?
3)Most of the EDM show systems I have seen use a ton of dual 18 boxes (matching the tops Brand Name )  in cardiod configuration.
Mike,

1) The M-Force driver is so radically different than any moving coil driver it has been hard to really compare, as it has a moving magnet and built-in amplification. The fact that Dave Rat decided to use them is a good indicator that they are a step above the best moving coil drivers in terms of output to space.
The PK design integrating the center grill as the motor heat sink would be a big advantage in the EDM world, where LF dynamic range is often no more than that of a sine wave, 3dB crest factor. PK had also been using some of the best pro 18" drivers, so they also seem to think the expense is warranted in terms of output to truck space.
2) No idea if the "newish" tech has gained much traction, riders typically request "X amount of 2x18" rather than output levels, though there can be as much as 15 dB level difference between 18" output..
3) Tried and true, but for big budgets the M-Force will probably start gaining traction, but just like with tapped horns, it is hard to convince anyone that one cabinet can do what 2 or 3 can until they hear it.

Art

Title: Re: PK Sound Gravity 30 Subwoofer
Post by: radulescu_paul_mircea on September 22, 2017, 06:55:42 pm
other companies are also using this new platform from Powersoft. Aura Audio, Funktion One (this one I heard twice and both times they managed to really impress me), Mag Audio, Audio Focus (40" design, 2 vs 6 dual 18 comparison .
https://m.facebook.com/groups/162278330843687?view=permalink&id=253343785070474
The tech is new, not very well understood and it really does perform extremely well. Because of the way the whole system works , with a pressure sensor  and 10 micro seconds lateny feedback, the sound is extremely tight and with very low distortions . The reactivity of the motor is letting the system to be a low loss oscillator that can be very efficient, the damping of the amp gives control over the motion of the diaphragm, the low impedance is dominating the enclosure's parameters and with the amp unit's you can virtually change the Thiel Small parameters of the drive to make it behave as you want it to.
That's why it still in development, being so much different and having so many thing to modify to get the best performance.


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Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Helge A Bentsen on September 23, 2017, 05:07:54 am
M-force is really nice, but you can still do EDM with dual 18", you just need to bring a serious one to your gig.

https://www.facebook.com/bernie.broderick/videos/10154803326492539/
https://www.facebook.com/bernie.broderick/videos/10154805721012539/
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: radulescu_paul_mircea on September 23, 2017, 05:56:02 am
M-force is really nice, but you can still do EDM with dual 18", you just need to bring a serious one to your gig.

https://www.facebook.com/bernie.broderick/videos/10154803326492539/
https://www.facebook.com/bernie.broderick/videos/10154805721012539/
Yes, of course you can. Having 80 18" TLW3000 and 104 B&C 15"SW115 drivers rubbed by 184 *1700 watt Powersoft amp modules really helps in an EDM concert . ANYA and Otto are really incredible.the OTTO is not about shear force. It's an extremely good and reliable tool to help fill the deep end of the Anya's ,which are very powerful down low by themselves.
This was last week, used in a market with 60K people and at 20-80 meters it sounded like a studio monitor flat to 25 Hz everywhere.(https://uploads.tapatalk-cdn.com/20170923/cfc7bb62821c0c4cc74f90d24524b2d7.jpg)(https://uploads.tapatalk-cdn.com/20170923/66e5cec747ff36f3b0d71a11a23886b0.jpg)

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Title: Re: PK Sound Gravity 30 Subwoofer
Post by: MikeHarris on November 19, 2017, 03:48:37 am
The driver looks like a update of Mr Danley's Servodrive concept.
Curious to hear what he thinks of the driver.
Tom...Ivan ??
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Ivan Beaver on November 19, 2017, 02:02:58 pm
The driver looks like a update of Mr Danley's Servodrive concept.
Curious to hear what he thinks of the driver.
Tom...Ivan ??
About the only thing is has in common with the servodrive is that the driver is round and it produces sound.  It pretty much stops there.

The driver in question is basically a "backwards" loudspeaker.  Instead of a moving coil, it has a moving magnet.

The servo drive was a motor (used in data transport machines) that rotated and went through a rotary to linear mechanism that drove the cones.  The cones were basically common cones (no magnet or voice coil) that were dipped in epoxy to make them stronger and had a half round surround for long excursion.

These drivers were then mounted in a horn to get extra output.
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Art Welter on November 19, 2017, 04:10:33 pm
These drivers were then mounted in a horn to get extra output.
The SDL Contra Bass used the dual 15" with dual 18" passive radiators.
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Ivan Beaver on November 19, 2017, 05:10:35 pm
The SDL Contra Bass used the dual 15" with dual 18" passive radiators.
Yeah, that one was the exception.

All of the others were horn loaded.

I believe the contrabass was developed to "talk to elephants" so it had to fit in the back of a jeep.

It later found favor for home listening.
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: MikeHarris on November 19, 2017, 11:41:14 pm
About the only thing is has in common with the servodrive is that the driver is round and it produces sound.  It pretty much stops there.

Both share a non-conventional method of driving the round thing that produces sound.

Every few years my client Byron Lee (RIP) would have me order belts for his SDL subs. Anything wear out on the PSoft ?
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Chris Grimshaw on November 20, 2017, 06:32:07 am
Anything wear out on the PSoft ?

Shouldn't do. It operates on a similar principle to a normal speaker, except it's the magnet that's being moved. That means you can bolt the voicecoil to a big ol' heatsink and drop 10KW into it.
Not really worth doing for smaller cones (moving coils propel those just fine) up to, say, 21". Past that, moving magnet seems to be the way to do it.

Chris
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Ivan Beaver on November 20, 2017, 07:28:54 am
Both share a non-conventional method of driving the round thing that produces sound.

Every few years my client Byron Lee (RIP) would have me order belts for his SDL subs. Anything wear out on the PSoft ?
So if we are going to go that route, I guess you could add piezo tweeters and "maybe" old (and some new) field coil speakers to the list, if "different" is the thing that makes them "common".
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: MikeHarris on November 20, 2017, 03:13:16 pm
Both share a non-conventional method of driving the round thing that produces sound.

Sorry to ruffle your feathers Ivan but I am clearly referring to alternate methods of driving the piston used for subs.
Maybe Tom could comment intelligently
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Keith Broughton on November 20, 2017, 03:29:29 pm
The SDL Contra Bass used the dual 15" with dual 18" passive radiators.
I heard one of these "back in the day" and was VERY impressed!
As for the Gravity30, I saw published specs of response and output but, once again, no frequency defined relationship  ::)
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Ivan Beaver on November 20, 2017, 05:09:24 pm
Sorry to ruffle your feathers Ivan but I am clearly referring to alternate methods of driving the piston used for subs.
Maybe Tom could comment intelligently
OK, they both use a piston.

But how that piston is driven has nothing in common-other than an audio signal.

And just to be clear- you did NOT say anything about subs.  You said a round thing that produces sound.  I gave examples of that.

I'm sorry if I insulted you, but I was just answering the "question" as it was presented.

Title: Re: PK Sound Gravity 30 Subwoofer
Post by: radulescu_paul_mircea on November 21, 2017, 10:28:00 am
The patent for the M-FORCE https://www.google.com/patents/WO2011125083A1?cl=en
And here is the technology behind it that had allowed it to perform as it does
http://www.powersoft-audio.com/en/docman/993-us-patent-improvements-to-systems-for-acoustic-diffusion/file

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Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Kevin McDonough on November 24, 2017, 02:25:10 pm
hey

well, to maybe meet somewhere in the middle I'd say it's a little similar to servodrive in that as you say Ivan, they're both piston like system to move the cone.

Very different i execution though, as (again as Ivan says) servodrive were a belt motor type system, where as this would be a bit closer o a solenoid.

On a traditional speaker it is a moving voice coil inside a fixed magnet. The voice coil had to be pretty thin and lightweight to make sure the cone can move at the required speed, which of course limits how much current can be put into it before it goes pop.

On the other hand, M-force as said flips this around and its the traditional magnet that is the moving part, and the voice coil the fixed part wrapping around it.

This means it can be as big and bulky as needed, with nice big heat sinks, and LOTS more current can be thrown at it.  This then makes cone weight less of an issue as it has the current, and hence motor force, to move much heavier weights. So I'm sure there is a 24", 30" and even 40" cone available that are made from a lightweight plastic rather than paper, so they're super rigid and can push a LOT of air at very high pressure.

K
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Tim McCulloch on November 24, 2017, 04:43:18 pm
hey

well, to maybe meet somewhere in the middle I'd say it's a little similar to servodrive in that as you say Ivan, they're both piston like system to move the cone.

Very different i execution though, as (again as Ivan says) servodrive were a belt motor type system, where as this would be a bit closer o a solenoid.

On a traditional speaker it is a moving voice coil inside a fixed magnet. The voice coil had to be pretty thin and lightweight to make sure the cone can move at the required speed, which of course limits how much current can be put into it before it goes pop.

On the other hand, M-force as said flips this around and its the traditional magnet that is the moving part, and the voice coil the fixed part wrapping around it.

This means it can be as big and bulky as needed, with nice big heat sinks, and LOTS more current can be thrown at it.  This then makes cone weight less of an issue as it has the current, and hence motor force, to move much heavier weights. So I'm sure there is a 24", 30" and even 40" cone available that are made from a lightweight plastic rather than paper, so they're super rigid and can push a LOT of air at very high pressure.

K

The fundamental difference is the use of a rotary servo motor and the belt linear motion transformer.

Pistonic transducers, in and of themselves, are not unique.
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Ivan Beaver on November 24, 2017, 06:24:12 pm
The fundamental difference is the use of a rotary servo motor and the belt linear motion transformer.

Pistonic transducers, in and of themselves, are not unique.
I made a "similar" speaker back in the 70s.  It was a moving magnet driver.

I took the coal dump mechanism (solenoid) from my train set, attached a construction paper cone to it with a cloth surround on a coat hanger frame.

I drove it from a Korean war era amplifier.

It made sound, but not very loud.  So I guess I was far ahead in my thinking  ;D ;D ;D.
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: radulescu_paul_mircea on November 24, 2017, 09:12:24 pm
It seems simple if one is looking at the driver and amplifier as independent units. The real thing is in fact the use of both as a complete system. Yes, the driver is a moving magnet fixed coil transducer with certain particularities, like the magnetic centering which allows it to work very with a centering suspension with the most important job of keeping the diaphragm from rocking and not to dictate the spring behavior.
The most important thing this system and the IPal system have is the possibility to change the parameters from a system with too much motor force in a virtual way and to modify the real behavior to a mathematical model without adding resistive losses and keeping the overall efficiency intact . So it's not just a motor. The evolution is not there in fact , because one could get the same results from normal driver if active cooling is used in some way. The evolution is in making this driver so efficient that it would not normally work in a reasonable enclosure and to be able to alter it as you want without loosing the efficiency advantage.

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Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Jim McKeveny on February 02, 2018, 07:48:22 am
I took the coal dump mechanism (solenoid) from my train set, attached a construction paper cone to it with a cloth surround on a coat hanger frame.

I drove it from a Korean war era amplifier.

I'm sad I am late to view this thread.

This style of curiousity is what drives great minds. You sound like a young Henry Kloss.
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Ted Christensen on February 15, 2018, 12:10:07 am
Pk audio is loved by edm because it's cheap. Really it's garbage even with Dolby lake. I have heard bands and edm and never impressed.
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Tim McCulloch on February 15, 2018, 01:16:13 am
Pk audio is loved by edm because it's cheap. Really it's garbage even with Dolby lake. I have heard bands and edm and never impressed.

I thought it was popular for EDM because it got REALLY F'ING LOUD.
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Ivan Beaver on February 15, 2018, 07:34:38 am
I thought it was popular for EDM because it got REALLY F'ING LOUD.
I used to think that EDM was only about really loud.

It is loud, HOWEVER, after dealing with it a good bit, doing various shows etc, I have come to the realization that (in many cases), if you can give them nice deep response and have good clear sound, they (many anyway) don't tend to run it as loud.

I think the "loudness" comes from the fact that often systems are used that do not provide the depth they are looking for or the clarity.

So all they know is "turn it up" until they get the impact/feeling they are looking for.

Actually, I have been surprised at some shows that they are not as loud as I had thought they would have been.

People still want to communicate, and if it is stupid loud you can't do that.

BUT, if your body is shaking from the deep low freq, then you can still talk over it.

But I will admit, that some people just want it "painful" or to be loud for the sake of being loud.

But many/most of the experienced pros in the field are more about the sound quality, rather than the actual SPL.

I have worked with some who have very good ears and know exactly what they are looking for.  Those are the easy ones to work with.
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Ted Christensen on February 15, 2018, 10:39:29 am
I thought it was popular for EDM because it got REALLY F'ING LOUD.

It didn't even get that loud.  Maybe 98db A at most. I managed to hear the big silver powered boxes, not sure the model numbers and don't really care but they were a bigger line array
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Don T. Williams on February 15, 2018, 03:47:31 pm
This may be begging the question, and it really isn't about how the subs sound, but how do you know what an electronically synthesized signal really should sound like?  With an acoustic guitar or piano or flute or vocal you have a ready reference.  Usually you want these to be louder without changing their sound characteristics.  EMD is a different animal.  I'm glad to hear from Ivan and Ted that there are shows that aren't just about level.  Just a comment.
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Ivan Beaver on February 15, 2018, 06:02:51 pm
This may be begging the question, and it really isn't about how the subs sound, but how do you know what an electronically synthesized signal really should sound like?  With an acoustic guitar or piano or flute or vocal you have a ready reference.  Usually you want these to be louder without changing their sound characteristics.  EMD is a different animal.  I'm glad to hear from Ivan and Ted that there are shows that aren't just about level.  Just a comment.
As with any signal, if you weren't there when it was recorded, how DO you know?

I have had some sounds come out during these shows that had me running for the amps.  People ask why, and then tell me "That is the way it is supposed to sound".

OK, sounded like shreaded cones to me or HF diaphragms bottoming out.
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Jeremy Young on February 15, 2018, 07:42:57 pm
Building on your thought Don.  I'd say the intended sound would be up to the artist's vision. 

I read somewhere once upon a time that when Tom Morello first started tracking the guitar solos for Rage Against the Machine's debut album, the engineers just looked at him blankly like "when does the guitar solo start, and why did you unplug your guitar?".  That might be lost on you if you're not familiar with his (now infamous) "style".

I'm sure any electric guitar player (who doesn't have ears on his knees) runs into this issue the first time he hears his amp close-mic'd.  It's not the "sound" you're used to (at head level 4' in front of a 4x12" cab off-axis from the very beamy drivers) but it's the sound everyone else has been hearing this whole time. 

It sure opened my eyes in my musician years, and once I started to care about it, I worked backwards to dial in my tone so it sounded (when mic'd) the way I intended originally. 

To get back to point, if the original EDM producer isn't at the gig, it's all just a guessing game, but if the source is electronic (that is, not a mic'd instrument), wouldn't a dual-channel FFT be a reasonable method to verify the source signal is accurately represented in the acoustic space?
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Ted Christensen on February 15, 2018, 07:57:37 pm
As with any signal, if you weren't there when it was recorded, how DO you know?

I have had some sounds come out during these shows that had me running for the amps.  People ask why, and then tell me "That is the way it is supposed to sound".

OK, sounded like shreaded cones to me or HF diaphragms bottoming out.

I know it was the rig because the other room had similar size hang of jbl vertec 4889s and it was no contender who won with both rooms pushing edm.
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Ivan Beaver on February 15, 2018, 08:02:22 pm
I'm glad to hear from Ivan and Ted that there are shows that aren't just about level. 
Here are what I consider "good guidelines" for levels at EDM type events.  Yes it can vary depending on a number of factors.

This is assuming a system that is truly flat to around 25Hz and has reasonable HF extension to 12-14KHz.

Around 100' away, 102-104 A slow and 125-130dB C fast is what you would measure on a simple SPL meter.

When designing a system, the peak SPL should be at least 10dB greater than those numbers.  15-20dB would be a better target, due to the abuse that these shows that often run non stop for 72 hours can do to a system in terms of heat build up.

It is a good idea to set thermal limiters at 1/4 continuous power.
Title: Re: PK Sound Gravity 30 Subwoofer
Post by: Tim McCulloch on February 16, 2018, 11:51:11 am
I know it was the rig because the other room had similar size hang of jbl vertec 4889s and it was no contender who won with both rooms pushing edm.

Those could have been operator or "performer" choice and I think it more likely than the rig itself.  We had a PK rig come through for a promoter we've worked with and the venue reported 'nothing like this before'.  Building damage, noise complaints from much further away than usual, police show up to verify permits and licenses are in place before telling complainers there's nothing they can do.

Word from the venue manager was that SPL was predominately ELF/LF with the tops only a little louder than we would have typically run them for an EDM event in that room.  They also had to use the lighting electrical service as the 100 amp audio service was deemed inadequate...

I do not doubt that you were underwhelmed with what you heard but I'm unconvinced it was the system's fault for that impression.

Tim "VerTec defender" Mc