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Speaker stacks and comb filtering

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May 24, 2005 5:57:54 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

Hi,
I sometimes see PA rigs that are made up of a stack of speakers piled on
top of eachother, and they are not all running seperate frequencies from
a crossover. From what I understand, doesn't this cause lots of comb
filtering problems?

If yes, is there any ways around this? How does it work with flying
arrays of speakers in bigger venues? They seem to get away with it!

What about when there are several drivers in one cab?

Suppose I had 2 12" cabs per side for instance, could I space these in
such a way so they'd only cause minimal filtering but enhancing the
volume a bit?

Cheers,

Mark.
--
May 24, 2005 5:57:55 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

Mark wrote:
> Hi,
> I sometimes see PA rigs that are made up of a stack of speakers piled
on
> top of eachother, and they are not all running seperate frequencies
from
> a crossover. From what I understand, doesn't this cause lots of comb

> filtering problems?

Using standard boxes that weren't meant to array can cause lots of comb
filtering when packed together by people who don't know any better,
yes.

> If yes, is there any ways around this?

The most you can do is splay the boxes at the front to reduce the
amount of pattern overlap to reduce the combing. With 90 degree boxes,
that's a pretty big splay.

>How does it work with flying
> arrays of speakers in bigger venues? They seem to get away with it!

Boxes used in large venues such as arenas, larger clubs with quality
installs, etc., are usually designed with tighter patterns so there is
less overlap of the coverage patterns. These patterns for a standard
trap array tend to be 60 degrees or less. With tighter patterns,
correct splay from box to box, and having them flown so they're further
from the listener are factors that make the array work. All arrayed
boxes have some comb filtering. It just a matter of how much, and if
it's being used in some way to control the pattern of the array (line
arrays/line sources are designed to use the interference to control the
pattern as an example).
>
> What about when there are several drivers in one cab?

If the drivers are placed so they are close enough together and crossed
at the proper frequencies, they will couple more then they interfere.
But there may be some summation issues that cause some combing there as
well depending on the design.

>
> Suppose I had 2 12" cabs per side for instance, could I space these
in
> such a way so they'd only cause minimal filtering but enhancing the
> volume a bit?

Yes, but the wider pattern boxes are more difficult. Generally with low
frequencies, you will get solid coupling that can augment output by
6dB, up to the point that the drivers loose their coupling (depending
on the driver size, drive distance, and relative wavelength). High
frequency drivers don't couple from box to box, as the relative
wavelengths involved are to short to allow for physical coupling,
regardless of the hype that some line arrays boast. For the frequencies
that don't fully couple from box to box. 3dB is the average gain with
the combination of constructive/destructive interference that results
(comb filtering).

Rupert
Anonymous
May 24, 2005 6:22:04 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

Mark wrote:
> I sometimes see PA rigs that are made up of a stack of speakers piled on
> top of eachother, and they are not all running seperate frequencies from
> a crossover. From what I understand, doesn't this cause lots of comb
> filtering problems?

You're probably looking at some type of line array, but this is not the
cause of comb filtering.

A comb filter is the effect created when sound travels from the source
to the receiver via two (or more) paths of differing length. It is an
interference pattern created when two copies of a sound are delayed by a
small amount and then added together. It gets its name from the fact
that when you look at the resulting sound across the frequency domain,
you see a display that looks like the teeth of a comb.

This effect is most noticeable for short time delays between the two
signal paths (e.g. 0.5ms). As the time delay rises, so the effect
becomes less audible. This is why it is more of a problem in small
listening spaces than large concert venues.

Chris W

--
The voice of ignorance speaks loud and long,
But the words of the wise are quiet and few.
---
Related resources
Anonymous
May 24, 2005 6:22:05 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

> You're probably looking at some type of line array, but this is not the
> cause of comb filtering.

Sorry, that's exactly what it is. The "line array" is just producing so
much comb filtering that it produces the effect it does. The interference
pattern is finer. There may be some behavior of "single source" output, but
not nearly enough.

The other attack to overcome comb filtering in multiple cabinet systems is
to have each single cabinet produce a defined radiation pattern, with
(ideally) zero phase response, and time aligned across the audio bandwidth.
Flying or stacking these building blocks properly provides more articulate,
higher quality sound reproduction. Right now, the closest performance to
this is achieved by the Sound Physics Labs gear, especially the TD1. You
can run them in their passive crossover mode, with minimal processing,
usually something to tie them into some subwoofers.

George's venerable Meyer MSL cabinets, some of the EAW(750, 850), and the
Renkus co-entrant coaxial designs are older designs that also work towards
this principle.

Now, I am not saying line arrays don't sound good. In the right application
and with proper technical deployment, they do sound allright. They are not,
however, the be all and end all to acoustic transducer design.

John
May 24, 2005 6:22:05 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

John Halliburton wrote:

> Now, I am not saying line arrays don't sound good. In the right
application
> and with proper technical deployment, they do sound allright. They
are not,
> however, the be all and end all to acoustic transducer design.

Agreed. There are many applications I see out there using lines where
traps would be more appropriate. But the marketing machine is strong.
It's nice to see designs like Tom's working towards more versatile
applications. Also companies like L'Acoustics working on good
innovative designs and not just line arrays. The ARCs are a pretty cool
trap system that implements some elements of the line array stuff,
along with that new Kudo box. Haven't had a chance to listen to them
yet, but they're very interesting.

Rupert
May 24, 2005 6:22:05 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

Scott Dorsey wrote:
> Rupert <foodsteaks@linkline.com> wrote:

> >Agreed. There are many applications I see out there using lines
where
> >traps would be more appropriate. But the marketing machine is
strong.
>
> I think what people most like about line arrays is that you can just
toss
> them up in any room and then tweak the parameters until they sound
decent
> without having to spend a lot of time and effort setting them up and
moving
> them around. And the narrow pattern can be a real advantage in very
live
> rooms.

While I understand what you're saying, there are a lot of bad sounding
line arrays out there because people do NOT know how to set them up,
and there is much less margin of error when setting up line arrays. In
fact, they are not really plug and play like you imply at all, as
compared to trap systems. This is one reason why companies like
L'Acoustics require that sound companies that purchase their V-DOSC and
DV-DOSC product have a least one trained, certified person in house.
This is mainly to protect their reputation and keep the system sounding
good because a qualified person is setting it up. Of course, once
they've sold the product, there's no way to ensure qualified people are
setting them up, so I've heard some pretty bad V-DOSC implementations,
but also many amazing ones.

Since line arrays purposely use destructive interference to control the
pattern, they can sound very bad if the box to box splay is not
precisely angled along the line's length. And since the coverage is
very focused, prediction software is required to figure out the correct
hang and how many boxes are required. This means measuring out the
venue with distance finders and laser protractors, etc. is a must. And,
more then one line per side may be required, along with various fills.
It can be tricky making them work right, especially in venues that
aren't ideally suited for them. This is why not any Joe Schmoe can walk
in with a line array and make it sound as good as that same untrained
Schmoe might be able to with trap system. They're two different
animals. Kind of like the difference between flying a plane and a
helicopter. Planes are relatively easy compared to helicopters. Someone
might be able to take the controls and land one in an emergency. If
your helicopter pilot keels over in flight, you're probably dead meat
;-)

Rupert
Anonymous
May 24, 2005 6:22:06 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

Rupert <foodsteaks@linkline.com> wrote:
>John Halliburton wrote:
>
>> Now, I am not saying line arrays don't sound good. In the right
>application
>> and with proper technical deployment, they do sound allright. They
>are not,
>> however, the be all and end all to acoustic transducer design.
>
>Agreed. There are many applications I see out there using lines where
>traps would be more appropriate. But the marketing machine is strong.

I think what people most like about line arrays is that you can just toss
them up in any room and then tweak the parameters until they sound decent
without having to spend a lot of time and effort setting them up and moving
them around. And the narrow pattern can be a real advantage in very live
rooms.

>It's nice to see designs like Tom's working towards more versatile
>applications. Also companies like L'Acoustics working on good
>innovative designs and not just line arrays. The ARCs are a pretty cool
>trap system that implements some elements of the line array stuff,
>along with that new Kudo box. Haven't had a chance to listen to them
>yet, but they're very interesting.

Even Stage Accompany is putting out a line array system now. I do fear
that, while the line array might be a great choice for touring shows
where setup time is limited and transport ease is critical, even so the
whole industry has gone line array crazy.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
May 24, 2005 8:12:53 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

> I sometimes see PA rigs that are made up of a stack of speakers piled on
> top of eachother, and they are not all running seperate frequencies from
> a crossover. From what I understand, doesn't this cause lots of comb
> filtering problems?

Not per se. What you get is mostly interference effects that add peaks and dips
to the net frequency response.

It's sort of the same thing, except the effect is spatial, rather than temporal.
Anonymous
May 24, 2005 8:50:23 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

"Mark" <marks@nospamhere.com> wrote in message
news:HrCdnRguCMwguQ7fRVnyig@pipex.net...
> Hi,
> I sometimes see PA rigs that are made up of a stack of
speakers piled on
> top of eachother, and they are not all running seperate
frequencies from
> a crossover. From what I understand, doesn't this cause
lots of comb
> filtering problems?

Depends on how the drivers are configured.

Take a bunch of bass drivers stacked edge-to-edge, crossed
over at a fairly low frequency. The sound fields around the
drivers tend to merge into one big blob.

Take a bunch of tweeters with woofers in-between and a
fairly high crossover frequency. Now you've got your broken
line array of independent drivers, and comb filtering may
abound.

> If yes, is there any ways around this?

Proximity and choice of crossover frequencies. The comb
filter effects are always there in theory, but if the teeth
of the comb are fine enough, you are unlikely to notice
them.

>How does it work with flying arrays of speakers in
bigger venues? They seem to get away with it!

Comb filtering effects are often less apparent the further
you are away from the array. In the reverberent field, there
are so many other interferring effects, such comb filtering
effects as exist might be swamped by the environmental
effects.

> What about when there are several drivers in one cab?

Proximity and choice of crossover frequencies.

> Suppose I had 2 12" cabs per side for instance, could I
space these in
> such a way so they'd only cause minimal filtering but
enhancing the
> volume a bit?

You don't space them, you try to put them as close as you
can. Coaxial is the best *spacing*! ;-)

There are some kinds of arrays, such as Bessel arrays N=5
(linear) and N=25 (square), that have vastly reduced issues
with comb filter effects. There are other ways to alter the
phase of the signals applied to the drivers in more complex
ways, so that the radiation patterns merge, change shape or
even point off-axis in useful ways.

My own opinion is that a lot of installed arrays are kinda
meatball surgery.
May 25, 2005 3:08:19 AM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

> I think what people most like about line arrays is that you
> can just toss them up in any room and then tweak the
> parameters until they sound decent without having to
> spend a lot of time and effort setting them up and moving
> them around.

As a Vertec user I'll chime in here.....
I've heard some BAD sounding line array setups... Everyone thinks
they're simple to throw up and tune, but there's more too it. Like any
other rig the systems engineer needs to understand what he's doing to set
things up right.

> And the narrow pattern can be a real advantage in very
> live rooms.

This is very true. There's a couple of rooms we do on a regular basis
that I wouldn't want to go near with a traditional trap box rig.

Mike Borkhuis
May 25, 2005 3:30:51 AM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

> I sometimes see PA rigs that are made up of a stack of speakers
> piled on top of eachother, and they are not all running seperate
> frequencies from a crossover.

It's VERY rare to NOT have a crossover in the setup. So, what you've
seen is probably one of two things.....
#1 - A big old stack of subwoofers....
#2 - An old school trap box speaker system...

> From what I understand, doesn't this cause lots of comb
> filtering problems?
> If yes, is there any ways around this?

Comb filtering is the result in the output of two cabinets interfering
with each other.
In an old school trap box rig that's taken care of by dispersion and the
angles between the boxes. For example the box might have a 60deg wide
coverage angle and be arrayed with a 30deg angle between cabinets. What
happens then is two boxes side by side spit out two columns of sound next to
each other that have minimal interferance with each other.
In a modern line array the comb filtering is designed in and helps give
the array the desired properties.

> How does it work with flying arrays of speakers in
> bigger venues? They seem to get away with it!

Goes back to the above....
A typical array might be 6 cabinets wide and 4 rows high. The array is
curved horizontally to spread out the sound to cover the seating area and
minimize the interference (comb filtering) between the cabinets... Each row
is also spread out (angled) to provided for vertical coverage and minimize
the interferance.

> What about when there are several drivers in one cab?

In the case of a main cabinet they're on different frequency ranges that
overlap in limited regions.
With subs, the drivers are close enough (reletive to the wavelength)
that they couple together and act like on big driver.

> Suppose I had 2 12" cabs per side for instance, could I
> space these in such a way so they'd only cause minimal
> filtering but enhancing the volume a bit?

If you've got a "standard" 90x40deg cabinet, simply place them side by
side with about a 45deg between the faces.....

Mike Borkhuis
Anonymous
May 25, 2005 3:30:52 AM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

> Comb filtering is the result in the output of two cabinets interfering
> with each other.
> In an old school trap box rig that's taken care of by dispersion and the
> angles between the boxes. For example the box might have a 60deg wide
> coverage angle and be arrayed with a 30deg angle between cabinets. What
> happens then is two boxes side by side spit out two columns of sound next to
> each other that have minimal interferance with each other.
> In a modern line array the comb filtering is designed in and helps give
> the array the desired properties.

Wait! Time out!

Comb filtering is used to describe effects produced when signals having a
relative time or phase differences are combined.

The "line column" effect of multiple speakers is also produced by interference
effects, but it's called interference. And it does not produce combing effects.

PLEASE, PLEASE, PLEASE don't start using the wrong terms. It can only confuse
people.
Anonymous
May 25, 2005 4:46:17 AM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

William Sommerwerck wrote:

> > I sometimes see PA rigs that are made up of a stack of speakers piled on
> > top of eachother, and they are not all running seperate frequencies from
> > a crossover. From what I understand, doesn't this cause lots of comb
> > filtering problems?
>
> Not per se. What you get is mostly interference effects that add peaks and dips
> to the net frequency response.
>
> It's sort of the same thing, except the effect is spatial, rather than temporal.

I always thought that comb filtering was due to time delays ( such as displacements
between multiple drivers driven with the same signal ). In effect it is indeed
'interference', just like those experiments in the physics lab with wave generators
and multiple slot sources.

Can you elaborate on your comment ?

Cheers, Graham
Anonymous
May 25, 2005 4:46:18 AM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

>> It's sort of the same thing, except the effect is spatial, rather than
temporal.

> I always thought that comb filtering was due to time delays (such as
displacements
> between multiple drivers driven with the same signal ). In effect it is indeed
> 'interference', just like those experiments in the physics lab with wave
generators
> and multiple slot sources.

> Can you elaborate on your comment ?

What you said is exactly correct.

There's no need to elaborate, if you see that, in a sense, "interference is
interference." The conditions, as you point out, though, are different. In the
case of combing, there is a temporal offset. In the case of line sources, there
is spatial offset.
Anonymous
May 25, 2005 5:19:00 AM

Archived from groups: rec.audio.pro (More info?)

On Tue, 24 May 2005 16:50:23 -0400, "Arny Krueger" <arnyk@hotpop.com>
wrote:

>My own opinion is that a lot of installed arrays are kinda
>meatball surgery.

Perzactly, except that you're possibly being too kind.

To the OP:
The more driver surface area you can fly, the better, IMO.
Downside is that all the surfaces have to contribute.

So, thinking in terms of wavelength can be the key to getting
a good working conceptual grip on the particulars. The issue
you're addressing involves wavelength both at the
source and at the listener.

At the source, the (vertical, hopefully) spacing between drivers is
only significant if larger than (the order of magnitude of) a
wavelength. At the listener, the axial, time-alignment, spacing
of drivers is, again, only significant approaching the order of
magnitude of a wavelength.

This is the general case. There are no general cases. Arf.

Good fortune, keep 'em flyin'

Chris Hornbeck
"The judge is on vinyl,
decisions are final,
Nobody gets a reprieve"
-Elliott Smith, "King's Crossing"
Anonymous
May 25, 2005 5:26:22 AM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

And the narrow pattern can be a real advantage in very live
> rooms.

Narrow? I find that an odd statement. Most line arrays are fixed between
90-120 degrees in the horizontal, vertical is "dependent on array design".
I guess my definition of "narrow" is different. Also, I don't agree with
the idea that someone can set up a line array and "tweak" the parameters
until it sounds good. What is essential there is having good factory
presets in the processing(and probably most folks don't want to find out how
much analysis went into getting those factory settings), and probably
leaving it stock-you'll more than likely be better off.
The very, very sweet thing about the SPL loudspeakers is their ability to
sound great right out of the box, with no processing. I could easily get
away without even using an EQ on FOH, but I do notch out a little midrange a
couple of db(-2db@600hz, IIRC).
To hear a big system with SPL product, get down to the King Biscuit Blues
Festival in Helena, Arkansas, usually Columbus Day weekend in October. Mike
Grimm of CSS Audio in East Peoria, Illinois is the provider. He's doing a
couple of other festivals around the Memphis area during the year too, as
well as festivals along Peoria's riverfront in the summer.

Best regards,

John
Anonymous
May 25, 2005 5:29:06 AM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

> I find the sound of line arrays very un natural
> regardless of who is running them

Perhaps I was being, ah, diplomatic in my assesment of line arrays. ;>)
Anonymous
May 25, 2005 5:43:38 AM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

> Comb filtering is the result in the output of two cabinets interfering
> with each other.
> In an old school trap box rig that's taken care of by dispersion and
> the angles between the boxes. For example the box might have a 60deg wide
> coverage angle and be arrayed with a 30deg angle between cabinets. What
> happens then is two boxes side by side spit out two columns of sound next
> to each other that have minimal interferance with each other.

Bull. It just isn't that clean, cut, and dry. In a traditional trap
cabinet, you get comb filtering due to separate sources(woofer, mid,
tweeter) mounted on a baffle. Then you set them up in multiples, adding to
the effect. Also, given that many designs combine a direct radiating woofer
and a horn for the high frequencies, you've got the additional problem of
the cone driver's dispersion characteristic going from something approaching
omni directional to 90 degrees(12" driver at the usual crossover frequency)
or 60 degrees(15" driver at the usual crossover frequency). Hence the wall
of mud in the 125-250hz region(at least one of the contributing factors),
since it bleed all around onto the stage reinforcing itself.
Now, I haven't even gotten into group delay issues. ;>)

> In a modern line array the comb filtering is designed in and helps give
> the array the desired properties.

You mean "unavoidable", not "designed in".
>
>> How does it work with flying arrays of speakers in
>> bigger venues? They seem to get away with it!
>
> Goes back to the above....
> A typical array might be 6 cabinets wide and 4 rows high. The array is
> curved horizontally to spread out the sound to cover the seating area and
> minimize the interference (comb filtering) between the cabinets... Each
> row is also spread out (angled) to provided for vertical coverage and
> minimize the interferance.
>
>> What about when there are several drivers in one cab?
>
> In the case of a main cabinet they're on different frequency ranges
> that overlap in limited regions.

Bull. See above explanation.


> With subs, the drivers are close enough (reletive to the wavelength)
> that they couple together and act like on big driver.

That won't hold up with an array of many subs, and I'm assuming you're only
referring to direct radiator(ie., vented cabinet designs). Once the group
of subs has a dimension that mathmatically falls into the subwoofer's
operating range, you can start to have the effect. Horn loaded subs will
sum as a single source though, another definite advantage.

Best regards,

John
Anonymous
May 25, 2005 5:49:02 AM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

John Halliburton wrote:

> Now, I am not saying line arrays don't sound good. In the right application
> and with proper technical deployment, they do sound allright. They are not,
> however, the be all and end all to acoustic transducer design.

Did the USA have the 4x12" column speaker back in the 70s ? Early example of
same.

Graham
Anonymous
May 25, 2005 5:49:03 AM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

> Did the USA have the 4x12" column speaker back in the 70s ? Early example
> of
> same.

How about all the way back to the 60's-Shure Vocalmasters, to name one.
Anonymous
May 25, 2005 5:49:04 AM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

John Halliburton <j_challiburton@ameritech.net> wrote:
>> Did the USA have the 4x12" column speaker back in the 70s ? Early example
>> of
>> same.
>
>How about all the way back to the 60's-Shure Vocalmasters, to name one.

Don't forget the Bogen columns with a dozen little 4" drivers either. Or
those awful McIntosh home speakers with the tweeter arrays.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
May 25, 2005 5:53:21 AM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

Scott Dorsey wrote:

> Rupert <foodsteaks@linkline.com> wrote:
> >John Halliburton wrote:
> >
> >> Now, I am not saying line arrays don't sound good. In the right
> >application
> >> and with proper technical deployment, they do sound allright. They
> >are not,
> >> however, the be all and end all to acoustic transducer design.
> >
> >Agreed. There are many applications I see out there using lines where
> >traps would be more appropriate. But the marketing machine is strong.
>
> I think what people most like about line arrays is that you can just toss
> them up in any room and then tweak the parameters until they sound decent
> without having to spend a lot of time and effort setting them up and moving
> them around. And the narrow pattern can be a real advantage in very live
> rooms.
>
> >It's nice to see designs like Tom's working towards more versatile
> >applications. Also companies like L'Acoustics working on good
> >innovative designs and not just line arrays. The ARCs are a pretty cool
> >trap system that implements some elements of the line array stuff,
> >along with that new Kudo box. Haven't had a chance to listen to them
> >yet, but they're very interesting.
>
> Even Stage Accompany is putting out a line array system now. I do fear
> that, while the line array might be a great choice for touring shows
> where setup time is limited and transport ease is critical, even so the
> whole industry has gone line array crazy.

Agreed.

Best system I *ever* heard was a classic Martin rig with W bins. I forget if it
had the Philishaves but I recall some radials in there too.

It was so clean that I only realised how loud it was ( on the balcony ) when I
tried talking to someone !

Nothing has ever since come close and that's 25+ yrs ago.

Everything's targeted at low freight cost and low rigging time now.


Graham
Anonymous
May 25, 2005 6:02:06 AM

Archived from groups: rec.audio.pro (More info?)

On Wed, 25 May 2005 01:43:38 GMT, "John Halliburton"
<j_challiburton@ameritech.net> wrote:

>> With subs, the drivers are close enough (reletive to the wavelength)
>> that they couple together and act like on big driver.
>
>That won't hold up with an array of many subs, and I'm assuming you're only
>referring to direct radiator(ie., vented cabinet designs). Once the group
>of subs has a dimension that mathematically falls into the subwoofer's
>operating range, you can start to have the effect. Horn loaded subs will
>sum as a single source though, another definite advantage.

This might sound very confusing to a layman, and might need some
more detail.

Thanks for any thoughts,

Chris Hornbeck
"As always, your mileage may vary, caveat emptor, save your receipt."
-John Hardy
Anonymous
May 25, 2005 6:52:31 AM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

John Halliburton wrote:

> > Did the USA have the 4x12" column speaker back in the 70s ? Early example
> > of same.
>
> How about all the way back to the 60's-Shure Vocalmasters, to name one.

A little too far back for me ! ;-)

The first gig I 'mixed' was with a Simms-Watts *200W* PA head with *6* channels
going through a couple of Vox 4x12 columns ! 1969 or 1970 IIRC.

Graham
Anonymous
May 25, 2005 7:23:36 AM

Archived from groups: rec.audio.pro (More info?)

On 24 May 2005 22:47:30 -0400, kludge@panix.com (Scott Dorsey) wrote:

>Don't forget the Bogen columns with a dozen little 4" drivers either. Or
>those awful McIntosh home speakers with the tweeter arrays.

Hey, it the was 70's; lighten up; "Stop making with the negative
waves, Moriarty" (-Donald Sutherland in _Kelly's Heroes_, not seen in
more than thirty years); still a funny line.

But yeah; didn't really work.

But the times were better, so....
Rock-n-roll,

Chris Hornbeck
"As always, your mileage may vary, caveat emptor, save your receipt."
-John Hardy
Anonymous
May 25, 2005 8:47:53 AM

Archived from groups: rec.audio.pro (More info?)

Chris Hornbeck wrote:

> Hey, it the was 70's; lighten up; "Stop making with the negative
> waves, Moriarty" (-Donald Sutherland in _Kelly's Heroes_, not seen in
> more than thirty years); still a funny line.

Kelly's Heroes makes a regular re-appearance every few yrs on UK TV, along
with Von Ryan's Express and other such marvels ! ;-)

I find Kelly's Heroes quite entertaining actually !

Graham
Anonymous
May 25, 2005 8:47:54 AM

Archived from groups: rec.audio.pro (More info?)

On Wed, 25 May 2005 04:47:53 +0100, Pooh Bear
<rabbitsfriendsandrelations@hotmail.com> wrote:

>> "Stop making with the negative
>> waves, Moriarty" (-Donald Sutherland in _Kelly's Heroes_, not seen in
>> more than thirty years); still a funny line.
>
>Kelly's Heroes makes a regular re-appearance every few yrs on UK TV, along
>with Von Ryan's Express and other such marvels ! ;-)
>
>I find Kelly's Heroes quite entertaining actually !

Here across the pond, there is a DVD; I really outta get one. My
memory of 1970 is maybe a little cloudy...

(Except for being drafted and married). No, I take it back;
it's *all* cloudy.

Thanks,

Chris Hornbeck
"Well, you could always ask Kevin Aylward for his opinion"
-I'm not really
May 25, 2005 1:06:48 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

>> In an old school trap box rig that's taken care of by dispersion
>> and the angles between the boxes. For example the box might
>> have a 60deg wide coverage angle and be arrayed with a 30deg
>> angle between cabinets. What happens then is two boxes side
>> by side spit out two columns of sound next to each other that
>> have minimal interferance with each other.
>
> Bull. It just isn't that clean, cut, and dry.

True. That's what I get for trying to offer a simplified
explination...... =)

>> With subs, the drivers are close enough (reletive to the wavelength)
>> that they couple together and act like on big driver.
>
> That won't hold up with an array of many subs, and I'm assuming
> you're only referring to direct radiator(ie., vented cabinet designs).

Yes, that's what I was thinking of.....

Mike Borkhuis
Anonymous
May 25, 2005 2:15:39 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

John Halliburton wrote:
> And the narrow pattern can be a real advantage in very live
> > rooms.
>
> Narrow? I find that an odd statement. Most line arrays are fixed between
> 90-120 degrees in the horizontal, vertical is "dependent on array design".
> I guess my definition of "narrow" is different.

The vertical coverage of each cabinet is usually "spec'd" at like 20 or
less degrees.

That really doesn't mean much in line array world though.. No one uses
just one cabinent.
Anonymous
May 25, 2005 5:45:19 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

If you have a row of multiple drivers, that automatically produces
differences in arrival times to the listener. I'm afraid you're describing
the same thing.

One definition:
A hollow coloration that, once recognized, is unmistakable. Caused by a
regularly spaced series of frequency-response peaks and dips, most often due
to interference between two identical signals spaced in time.
Anonymous
May 25, 2005 8:01:18 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

George Gleason wrote:
>
> Thanks Gene
> I don't visit PSW and navigating it is confusing for me
> could you please post a url
> I am very intrested in this
> George

Certainly...

This should work, let me know if it doesn't.

http://srforums.prosoundweb.com/index.php/t/6658/6617/
Anonymous
May 25, 2005 11:53:39 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

"John Halliburton" <j_challiburton@ameritech.net> wrote in message
news:4nGke.1185$rk.125@newssvr17.news.prodigy.com...
> Now, I am not saying line arrays don't sound good. In the right
> application and with proper technical deployment, they do sound allright.
> They are not, however, the be all and end all to acoustic transducer
> design.
>
Amen.

The three worst festival sounds I have heard were from line arrays two of
which weren't set up right.

1. Glastonbury main stage - Brit Row set up a V-dosc system that sounded
like it had a bad 70s flanger over the whole mix.
2. Download festival at Donnington - No PA wings so the vertec system was
blowing around in the wind. Sounded like someone throwing a heavy blanket
over the PA then removing it every few seconds.
3. Zillo festival in Hildesheim 1997 - sound company forgot to turn the
limiters on. Band before mine used pyro and took out 26 bass drivers. I was
left mixing through a rig sounding like an AM radio.

Line arrays can work well if set up properly and used in the right
application but they are very much flavour of the month and are being used
for everything where a traditional box will often work better. Just look at
the Pink Floyd division Bell tour. Best sound I have ever heard and all done
with flashlight.

Phildo
Anonymous
May 25, 2005 11:56:16 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

"Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:4293CC81.34C7977B@hotmail.com...
> Best system I *ever* heard was a classic Martin rig with W bins. I forget
> if it
> had the Philishaves but I recall some radials in there too.
>
> It was so clean that I only realised how loud it was ( on the balcony )
> when I
> tried talking to someone !
>
> Nothing has ever since come close and that's 25+ yrs ago.

Must take you to an event where there is an Opus system when I get home.
Will blow you away.

Phildo
Anonymous
May 26, 2005 12:02:36 AM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

"Mark" <marks@nospamhere.com> wrote in message
news:HrCdnRguCMwguQ7fRVnyig@pipex.net...
> Hi,
> I sometimes see PA rigs that are made up of a stack of speakers piled on
> top of eachother, and they are not all running seperate frequencies from a
> crossover. From what I understand, doesn't this cause lots of comb
> filtering problems?
>
One other thing you need to watch out for when stacking boxes is drivers
coupling.

I remember the first time I took out an EV deltamax rig. 8 boxes per side, 2
high, 4 wide. I recalled being told something about inverting boxes and
tweeter coupling so turned the whole top line upside down so all the
tweeters coupled together. Once my ears had stopped bleeding I went and
inverted every other box and it sounded much better.

Didn't do that again.

Phildo
Anonymous
May 26, 2005 1:52:52 AM

Archived from groups: rec.audio.pro (More info?)

Chris Hornbeck wrote:

> On Wed, 25 May 2005 04:47:53 +0100, Pooh Bear
> <rabbitsfriendsandrelations@hotmail.com> wrote:
>
> >> "Stop making with the negative
> >> waves, Moriarty" (-Donald Sutherland in _Kelly's Heroes_, not seen in
> >> more than thirty years); still a funny line.
> >
> >Kelly's Heroes makes a regular re-appearance every few yrs on UK TV, along
> >with Von Ryan's Express and other such marvels ! ;-)
> >
> >I find Kelly's Heroes quite entertaining actually !
>
> Here across the pond, there is a DVD; I really outta get one.

I use ebay for DVDs. What's the difference between used and new ?

http://search.ebay.com/kellys-heroes_W0QQsojsZ1QQfromZR...

Curiously the prices seem slightly keener on the UK site ( or is it just the
dollar rate ? ).

> My memory of 1970 is maybe a little cloudy...
>
> (Except for being drafted and married). No, I take it back;
> it's *all* cloudy.

Hmmm - I remember 1970 ok. Some good reasons to.

Graham
Anonymous
May 26, 2005 4:01:14 AM

Archived from groups: rec.audio.pro (More info?)

On Wed, 25 May 2005 13:45:19 GMT, "John Halliburton"
<j_challiburton@ameritech.net> wrote:

>If you have a row of multiple drivers, that automatically produces
>differences in arrival times to the listener. I'm afraid you're describing
>the same thing.
>
>One definition:
>A hollow coloration that, once recognized, is unmistakable. Caused by a
>regularly spaced series of frequency-response peaks and dips, most often due
>to interference between two identical signals spaced in time.

I built a couple of stage foldback monitors with nine four inch
drivers in each. The horizontal layout seems to exaggerate the
comb filtering; ouch. Folks tried to tell me, but *I knew better*.

Strangely, they seem to have a very sharp distance beyond which
the sound coheres; its about six or eight feet axially. But I
wouldn't recommend the project except as an experiment. Pretty
clean and rugged but certainly not for everybody.

Or, a multiply-delayed, multiply-amplified design focused on
the performer. Or a curved box...

Chris Hornbeck
"Well, you could always ask Kevin Aylward for his opinion"
-I'm not really
May 26, 2005 12:08:01 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

You bring up a good point about line arrays and wind. Since they use a
set HF of drivers in a single column, the pattern really can get
trashed even in low wind conditions. With a multi box trap array, the
effect tends to be less pronounced, as when one HF drivers pattern is
blown out of your listening field, another one usually blows in. You
may still get some swish, but at least the high end won't disappear
altogether.

Rupert
Anonymous
May 26, 2005 10:03:31 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

Phildo wrote:

> "Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
> news:4293CC81.34C7977B@hotmail.com...
> > Best system I *ever* heard was a classic Martin rig with W bins. I forget
> > if it
> > had the Philishaves but I recall some radials in there too.
> >
> > It was so clean that I only realised how loud it was ( on the balcony )
> > when I
> > tried talking to someone !
> >
> > Nothing has ever since come close and that's 25+ yrs ago.
>
> Must take you to an event where there is an Opus system when I get home.
> Will blow you away.

Please do !

The rig in question was Manfred Mann's Earthband btw.

My funny email addy works FYI. It seems to be too long to attract the spammers
luckily.


Grahan
Anonymous
May 26, 2005 10:09:54 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

Rupert wrote:

> You bring up a good point about line arrays and wind. Since they use a
> set HF of drivers in a single column, the pattern really can get
> trashed even in low wind conditions. With a multi box trap array, the
> effect tends to be less pronounced, as when one HF drivers pattern is
> blown out of your listening field, another one usually blows in. You
> may still get some swish, but at least the high end won't disappear
> altogether.

If there's wind it wins. Period ! Nothing can defeat it ( other than a
wide dispersion but you still get the wow and flutter effect )

I talk from experience.

Graham
Anonymous
May 26, 2005 10:53:26 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

In article <3fm68cF8gpdhU3@individual.net>, Phildo <Phil@phildo.net> wrote:
>
>
>The three worst festival sounds I have heard were from line arrays two of
>which weren't set up right.

HAH! You should have been at the festival I was at last week. A bunch
of 1970s Peavey speakers, all mismatched, one of which had a buzzing grille
and one of which had a blown woofer. Powered through 22 ga zip cord
from one side of a CS800 (since the other side was dead). A Sunn console.
I was amazed at how bad the Sunn console was. I hadn't realized until
I listened to the main feed in the truck just how bad it was. Car
stereo speakers mounted in plywood boxes for monitors.

It still keeps coming back to me at night, like a horrible nightmare that
won't go away.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
May 27, 2005 3:32:53 AM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

On Wed, 25 May 2005 19:53:39 +0100, "Phildo" <Phil@phildo.net> wrote:

>
>"Just look at
>the Pink Floyd division Bell tour. Best sound I have ever heard and all done
>with flashlight.
>

Uhhhh . . . what't the best flashlight for under $45,000.00 ?
Anonymous
May 27, 2005 1:05:36 PM

Archived from groups: rec.audio.pro (More info?)

On Thu, 26 May 2005 18:09:54 +0100, Pooh Bear
<rabbitsfriendsandrelations@hotmail.com> wrote:

>
>Rupert wrote:
>
>> You bring up a good point about line arrays and wind. Since they use a
>> set HF of drivers in a single column, the pattern really can get
>> trashed even in low wind conditions. With a multi box trap array, the
>> effect tends to be less pronounced, as when one HF drivers pattern is
>> blown out of your listening field, another one usually blows in. You
>> may still get some swish, but at least the high end won't disappear
>> altogether.
>
> If there's wind it wins. Period ! Nothing can defeat it ( other than a
>wide dispersion but you still get the wow and flutter effect )
>
>I talk from experience.
>
>Graham

So, a mega-Leslie effect? If I think closer, it happens more often
than one would think -- to greater or lesser extent; depending on the
distance of a listener to sound sources and of speed of moving air
masses and layers (wind, temperature differences etc). The effect,
especially at speech [politiciains, take note] can be funny. Weally!

It is interesting to think about it alltogether.

Edi Zubovic, Crikvenica, Croatia
May 27, 2005 3:40:39 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

Phildo wrote:

... snip ..

> Line arrays can work well if set up properly and used in the right
> application but they are very much flavour of the month and are being used
> for everything where a traditional box will often work better. Just look at
> the Pink Floyd division Bell tour. Best sound I have ever heard and all done
> with flashlight.
> Phildo

I went to the Pink Floyd show at Earls Court, 1994 I think it was at the
tender age of 14. I remember it sounded pretty amazing; I remember I
was slightly late (long story involving the guy who look us being
dragged by a car across the front of Earls Court).. Anyway, on
approaching the entrance to the hall were they had already started
playing, I could feel the bass pretty much shaking the place and going
right through me. I hadn't heard anything like it before at the time.
I think it was during one of the keyboard intro's.

Good job they didn't play "the brown note" ;-)

Mark.
--
Anonymous
May 27, 2005 4:27:53 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

"Scott Dorsey" <kludge@panix.com> wrote in message
news:D 75k16$8ff$1@panix2.panix.com...
> In article <3fm68cF8gpdhU3@individual.net>, Phildo <Phil@phildo.net>
> wrote:
>>
>>
>>The three worst festival sounds I have heard were from line arrays two of
>>which weren't set up right.
>
> HAH! You should have been at the festival I was at last week. A bunch
> of 1970s Peavey speakers, all mismatched, one of which had a buzzing
> grille
> and one of which had a blown woofer. Powered through 22 ga zip cord
> from one side of a CS800 (since the other side was dead). A Sunn console.
> I was amazed at how bad the Sunn console was. I hadn't realized until
> I listened to the main feed in the truck just how bad it was. Car
> stereo speakers mounted in plywood boxes for monitors.
>
Yeah but these were big, supposedly professional festivals with tens of
thousands of people all pissed off at the sound.

Phildo
Anonymous
May 27, 2005 4:27:54 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

In article <3foaqgF8sn86U1@individual.net>, Phildo <Phil@phildo.net> wrote:
>"Scott Dorsey" <kludge@panix.com> wrote in message
>> In article <3fm68cF8gpdhU3@individual.net>, Phildo <Phil@phildo.net>
>>>
>>>The three worst festival sounds I have heard were from line arrays two of
>>>which weren't set up right.
>>
>> HAH! You should have been at the festival I was at last week. A bunch
>> of 1970s Peavey speakers, all mismatched, one of which had a buzzing
>> grille
>> and one of which had a blown woofer. Powered through 22 ga zip cord
>> from one side of a CS800 (since the other side was dead). A Sunn console.
>> I was amazed at how bad the Sunn console was. I hadn't realized until
>> I listened to the main feed in the truck just how bad it was. Car
>> stereo speakers mounted in plywood boxes for monitors.
>>
>Yeah but these were big, supposedly professional festivals with tens of
>thousands of people all pissed off at the sound.

It's true that there is a substantial difference between hundreds of people
pissed off with the sound and tens of thousands of people pissed off at
the sound. For one thing, when there are enough people the feeling of
anonymity makes them more apt to set fire to things.

On the other hand, setting fire to that Sunn is something I considered
doing myself.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
May 27, 2005 4:28:43 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

"Willie K. Yee, MD" <wkyee@bestweb.net> wrote in message
news:42965c74.128444578@nntp.bestweb.net...
> On Wed, 25 May 2005 19:53:39 +0100, "Phildo" <Phil@phildo.net> wrote:
>
>>
>>"Just look at
>>the Pink Floyd division Bell tour. Best sound I have ever heard and all
>>done
>>with flashlight.
>>
>
> Uhhhh . . . what't the best flashlight for under $45,000.00 ?
>
The big maglites I think. Useful for security and idiot-bashing as well as
illumination.

Phildo
Anonymous
May 27, 2005 4:47:01 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

"Mark" <marks@nospamhere.com> wrote in message
news:o o-dndqZSceTZAvfRVnytQ@pipex.net...
> Good job they didn't play "the brown note" ;-)
>
Myth.

The spook note however is another story.

Phildo
May 27, 2005 4:47:02 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

Phildo wrote:
> "Mark" <marks@nospamhere.com> wrote in message
> news:o o-dndqZSceTZAvfRVnytQ@pipex.net...
>
>>Good job they didn't play "the brown note" ;-)
>>
>
> Myth.
>
> The spook note however is another story.
>
> Phildo
>
>

I didn't realise there was a spook note. I've heard that general very
low frequencies can make you feel on edge, like from huge power
transformers, don't know if its true.

Then there are the sounds they use in horror films to scare you..

Is there a particular note then that does it?

Mark.
--
Anonymous
May 27, 2005 6:33:24 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

> On the other hand, setting fire to that Sunn is something I considered

Quite possibly you should have been duty bound to do the right thing. ;>)

JHH
Anonymous
May 27, 2005 6:35:06 PM

Archived from groups: alt.audio.pro.live-sound,rec.audio.pro (More info?)

> I didn't realise there was a spook note. I've heard that general very low
> frequencies can make you feel on edge, like from huge power transformers,
> don't know if its true.

On a warm day, if you're that close to big power transformers making noise,
I'd be nervous too.

JHH
!