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This topic comprises 3 pages: 1 2 3
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Author
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Topic: Long speaker runs VS. short runs.
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Steve Guttag
We forgot the crackers Gromit!!!
Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 04-26-2018 10:50 AM
quote: Tony Bandiera Jr
The costs of individual runs of smaller conduits (or MC cable) WILL always be greater than one larger conduit capable of holding the same amount of wire
We are entitled to our experiences, I guess. I've never had a quote come in larger for dropping a couple of circuits versus a larger (or couple of semi-large) conduit runs. And on new construction, the circuits generally have zero or near zero cost addition as they are just drawn in as part of the entire electrical spec.
You use of a separate circuit for each speaker is just plain silly. You have 2400VA available per circuit presuming that the amps have no capacitors. Actual current draw on an amp is going to be far less as it stores much of the power it needs and the odds a stage speaker hits the current capacity driving even all three stage speakers is near zero unless you have very inefficient speakers as stage speakers. Subwoofers? That is a different story, yes, I like separate circuits for them, they can and do suck a lot of power for short periods of time.
And you don't need a NOC for monitoring on a semi-current DSP system (any by semi-current, I mean within the last 10-15 years). The whole fault analysis for cinema goes as far back as the DCP amplifiers, at least so we are approaching 20-years.
I suppose we'll have to agree to disagree on methodologies.
Scott as to what types of venues? In the A/V world most any type as it can handle all of the usual A/V needs, including VTC (they even have cameras now for it).
In Cinema, up until now, the vast majority have been Atmos systems. However, QSC just came out with a nifty I/O module the DCIO and THE DCIO-H. They provide what one would need on a typical 5.1/7.1 cinema. It has 16 channels of AES audio in, mic/line in. Monitor Out (both line and amplified), HI/VI out, GPIO and the "H" version has HDMI audio in as well as pass-through out for alternate content (with DTS and Dolby decoding).
Price wise, the DCIO-H is cheaper that most any cinema processor however, once you add in the cost of the core(s) and user interface (typically a 7 inch touchpanel but it could be a phone/pad/PC), you really need to get it up to 4 screens or more for a strict cost benefit. A CORE 510c can handle up to 256 channels in/out so that could be a lot of cinemas. There is a full redundant core mode (completely separate core) so if one tanks, you have not just a spare tire, you have the car. The QLAN network uses normal IT switches (from an approved/tested list) and can have two completely separate networks for again, redundancy and reliability (most all QSYS devices have dual NICs for this too.
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Marcel Birgelen
Film God
Posts: 3357
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012
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posted 04-26-2018 02:04 PM
I think the "end game" here will be active speakers, especially with the increasing adoption of Multi-dimensional audio, it makes sense. For lights, we've been doing something similar for years already: Splitting power and signalling with e.g. DMX. Obviously, those mostly have been lower bandwidth applications, but bandwidth on all kinds of transmission technology has become cheap over the years.
In essence, every speaker will have both 110/220V power and a "data bus", which will most likely just be Cat5e or Cat6 Ethernet carrying something like to QLAN, Dolby Atmos Connect, CobraNet or equivalent protocol.
Yes, having an amplifier in each speaker does have some practical downsides, like the increased weight and need for extra cooling. Then again, I've seen a shrinkage in average auditorium size in the last few years and an increased density of speakers could also allow for a less power-dense speaker design.
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Steve Guttag
We forgot the crackers Gromit!!!
Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 04-26-2018 10:44 PM
Yeah, I think the notion of self-powered speakers as a cost/installation savings is a false one except, maybe (and it is just a maybe for me) for stage and subwoofers. Cooling isn't the issue as the amps are bound to be Class-D at this point so the speaker will provide sufficient cooling. It is the wiring. You now have to have outlets everywhere with power cords going everywhere and, on top of that, signal/network connections going everywhere. You've doubled your wiring and involved another trade (electricians) as well as the circuits to handle all of that.
The surround speaker wires are rarely above 16awg unless you are talking about the front most ones in an Atmos system. For 5.1/7.1 system, 16 gauge is all you are going to need for all but the largest rooms. So the wire isn't too fat.
I suppose wiring could be reduced if the CAT cables daisy-chained, which would seem good...until...one failed and took the entire string out! You'd have to have a relay or like item in each speaker that would crowbar if the power went off in the speaker to ensure that the chain wasn't broken. Or...just run the speaker wire to the nearest amplifier, which for some, is just on the other side of the booth wall, or in the boothless theatre, behind the screen.
BTW, MIT has a behind-the-screen rack that is pretty nifty. Has filters front/rear and the quietest fans I've seen on the top to pump air out (and can be connected to an HVAC system, if desired.
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Marcel Birgelen
Film God
Posts: 3357
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012
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posted 04-27-2018 03:36 AM
Ethernet actually is a bus protocol, you don't necessarily need a switch to string some devices together, you can even hook quite some of them together using passive splitters.
I agree on the practical issues, at least for now. But I'm pretty sure we're looking at a world where Ethernet in some form will be the primary data interface. The massive economy of scale behind it will more or less even dictate it and you see it also creeping into the cinema industry, with stuff like Atmos Connect and QSC's QSYS/QLAN.
For live events, we're now seeing stuff like NDI making its way in for live HD and 4K video transmission over IP/Ethernet, rapidly replacing SDI. And for lightning, stuff like Art-Net (essentially DMX over UDP) is creeping in too.
Most speakers for live events have been active speakers for a while now, although most of them still expect a balanced analog input rather than a digital one. Heat dissipation almost never seems to be a problem, since you've got a whole room to dump your heat in, in many cases no active cooling is even needed, just some good heatsinks. And for energy efficiency: Instead of more cooling in the booth, you now need to cool the auditorium a bit more.
Although concentrating heat might sound like it makes it more efficient to cool, from the collective experience we gathered with high-density datacenters over the years, we know that this is generally not the case. It's usually more efficient to spread your heat load over a larger volume, because the ΔT will be lower.
As for using Ethernet as the absolute backbone for "all-things-data", we've actually been looking at stuff like GPON, where we can use a "single" string of fiber to hook up all kinds of subscribers, which will then all get an optical isolated assignment. All splitters are purely passive and relatively cheap. For now, the terminals and concentrators are still a bit pricey, but I suspect we'll see a dramatic decrease in cost of this kind of equipment in the coming years. One big advantage: fiber is pretty cheap nowadays, especially compared to heavy bundles of copper wire, it is also not as fragile as some make it out to be.
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Tony Bandiera Jr
Film God
Posts: 3067
From: Moreland Idaho
Registered: Apr 2004
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posted 04-28-2018 10:02 AM
Steve Guttag, so which is it? I see a pretty big contradiction in your positions on powered speakers. (Bold emphasis added by me in the quotes)
To me, you responded:
quote: Steve Guttag
I've never had a quote come in larger for dropping a couple of circuits versus a larger (or couple of semi-large) conduit runs. And on new construction, the circuits generally have zero or near zero cost addition as they are just drawn in as part of the entire electrical spec.
You use of a separate circuit for each speaker is just plain silly. You have 2400VA available per circuit presuming that the amps have no capacitors. Actual current draw on an amp is going to be far less as it stores much of the power it needs and the odds a stage speaker hits the current capacity driving even all three stage speakers is near zero unless you have very inefficient speakers as stage speakers. Subwoofers? That is a different story, yes, I like separate circuits for them, they can and do suck a lot of power for short periods of time.
Oh, and BTW I promise you that even in new construction, there is no such thing as "zero or near zero" cost addition, as all the materials and labor still has to be paid for, and in many cases, the EE has to review and approve any changes, which is NEVER free.
And then to Carsten (and/or Marcel) you responded with this:
quote: Steve Guttag
Yeah, I think the notion of self-powered speakers as a cost/installation savings is a false one except, maybe (and it is just a maybe for me) for stage and subwoofers. Cooling isn't the issue as the amps are bound to be Class-D at this point so the speaker will provide sufficient cooling. It is the wiring. You now have to have outlets everywhere with power cords going everywhere and, on top of that, signal/network connections going everywhere. You've doubled your wiring and involved another trade (electricians) as well as the circuits to handle all of that.
Care to explain that? ![[Big Grin]](biggrin.gif) ![[Wink]](wink.gif)
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Steve Guttag
We forgot the crackers Gromit!!!
Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 04-28-2018 10:54 AM
No problem Tony,
You wanted a separate circuit for EACH SPEAKER, which is silly. I said to drop a couple of circuits for the entire behind the screen sound. There are, at least 3 stage speakers and subwoofer(s) with the subwoofers being the big draw and the others considerably less so.
You can promise whatever you please, I four decades in this and, as I said, we have our own experiences, yours differs from mine. I've had construction companies price out theatres strictly on square-foot for everything included because pricing out every screw, nut, fixture would put costing at more than it would save in materials. Unless you have something that is way out of the norm (and electrical circuits behind the screen, from the booth have not been since masking (and sometimes curtain machines and self-powered subwoofers like the KT90 of the 80s/90s...etc) have been there traditionally, I've never seen an add for having additional circuits back there outside of normal cinema construction. I guess you have, and that is fine.
There is a difference between self-power speakers and merely putting the amplifiers by the speakers. The failure points are different and the installation is different. Putting the amps near the speakers consolidates wiring. All of the power is brought to one place, not 4 places. All of the signal is brought to one place (the amps) not to four places. The speaker wires, that which costs, copper wise, are kept short, especially in 3 and 4-way systems.
I know you want to "catch" me but there is nothing to catch. You are stuck on applying an older design when new equipment MAY make that design no longer be the more cost effective solution (let alone performance).
And then there is the Meyer stuff where indeed, EVERYTHING is self-powered and expensive but everything about a Meyer system is expensive. Then again, they have a reputation of being one of the best sounding systems in the world. There is something to being able to control the sound, including the amplifiers.
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Marcel Birgelen
Film God
Posts: 3357
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012
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posted 04-28-2018 11:08 AM
quote:
And then to Carsten (and/or Marcel) you responded with this:
Tony, please don't put my name on quotes that aren't mine, even if it's in parenthesis.
I've clearly stated that I see a definitive move forward into a "single digital data transmission system", being Ethernet and most likely also a move towards active speakers in the long run. I also acknowledge the practical implications for now and why those setups aren't yet pretty much common.
I'm not all-seeing, but I'm trying to extrapolate from what we've seen in other, similar markets. And we've already seen something similar happen for "live" setups, where almost all speakers nowadays are some form of active speakers. No matter whether it's a "classical" setup or a line array setup or a mix of both. I've also seen similar things happen in the theme park industry, and although the applications are somewhat different, there is also considerable overlap between those and the cinema industry.
I don't see a move where we're starting to put amplifiers near speakers. Besides for stage speakers in some configurations, this is just backwards in my opinion.
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