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Author Topic: introduction & sub question  (Read 16618 times)

biton walstra

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introduction & sub question
« on: July 04, 2011, 11:08:58 am »

hi all,

i'm the sound guru at our church, new life church, at crawley uk.
my back ground is coming from sound gigs as roadie / sound engineer since 1978 both fulltime as next to my main it job. this was all non church work.

the church is a very small church with about room for about 40 people. mostly we have about 25 people in our sunday service.

the sound system used were 2 speakers bolted to the back wall with all feedback problems etc.

budget is almost non existing so i have created a mini line-array system and using the 'old' speakers as subs (wired the woofer directly). this works very well and i'm pleased with this. total cost about 250 including reusing existing gear.


you can find some more pictures here; http://www.bit4net.com/images/mini_line_array/

now my question;

should i fly the subs or not? i have them now temp on the side against the wall not really the best place. we have also little stars (childeren) on mondays. as you can see on the pictures we have still place enough on the bar to fly them.

made the array with 1c behringer speakers. main amp is an 4 channel amp to drive both arrays, other room & foldback speakers. the subs are powered by an old 6 channel amp.


many thanks,
biton
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Rory Buszka

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Re: introduction & sub question
« Reply #1 on: July 04, 2011, 01:15:52 pm »

This is a creative-looking solution, but I doubt the boxes are actually performing like an idealized line array (where the individual speakers are designed to have very narrow vertical dispersion). Still, it has to be better than having the speakers on the back walls, and I understand the budget constraints that a lot of smaller churches are operating under (usually no money to do anything unless something vital should break down).

If you're handy with a table saw and jigsaw, you might try building a pair of subwoofers from the myriad of plans out there on the internet and some inexpensive (but better than the Behringer) drivers; just wiring up the woofers in whatever FR mains you had before won't get you any real bass below about 80 Hz, and a purpose-designed subwoofer enclosure will achieve much deeper bass response due to its lower tuning.

What is the model number of the Behringer speakers used in the 'line' arrays?

hi all,

i'm the sound guru at our church, new life church, at crawley uk.
my back ground is coming from sound gigs as roadie / sound engineer since 1978 both fulltime as next to my main it job. this was all non church work.

the church is a very small church with about room for about 40 people. mostly we have about 25 people in our sunday service.

the sound system used were 2 speakers bolted to the back wall with all feedback problems etc.

budget is almost non existing so i have created a mini line-array system and using the 'old' speakers as subs (wired the woofer directly). this works very well and i'm pleased with this. total cost about 250 including reusing existing gear.


you can find some more pictures here; http://www.bit4net.com/images/mini_line_array/

now my question;

should i fly the subs or not? i have them now temp on the side against the wall not really the best place. we have also little stars (childeren) on mondays. as you can see on the pictures we have still place enough on the bar to fly them.

made the array with 1c behringer speakers. main amp is an 4 channel amp to drive both arrays, other room & foldback speakers. the subs are powered by an old 6 channel amp.


many thanks,
biton
« Last Edit: July 04, 2011, 01:19:20 pm by Rory Buszka »
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biton walstra

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Re: introduction & sub question
« Reply #2 on: July 04, 2011, 06:50:03 pm »

hi rory,

actually the line-array works very well as i have almost an equal sound coverage throughout the room, bear in mind it's a small room. i used 4 behringer 1c monitor speakers and a behringer cx2310 crossover, on top of the two limiter compressors;

high pass starts at 120hz and then the subs lowpass cuts at 75hz leaving a small gap to compensate the buildings resonance around 100hz.

these are the 'old' speakers modified as subs;

as you can see i have stacked them with the vents close together to gain more bass. the woofers are connected directly by passing filters and tweeters.

i do like the idea of using aux of the mixing console to drive the subs but i already used all the pre & post aux for other things, foldback, hearing loop and effects.

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g'bye, Dick Rees

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Re: introduction & sub question
« Reply #3 on: July 04, 2011, 07:07:16 pm »

hi rory,

actually the line-array works very well as i have almost an equal sound coverage throughout the room, bear in mind it's a small room. i used 4 behringer 1c monitor speakers and a behringer cx2310 crossover, on top of the two limiter compressors;


First of all, it's NOT a "line array".....it's a collection of near field (stuodio) monitor speakers.  As such, their wide pattern is not at all likely to combine coherently in any type of array.  They are made as stand alone monitors and not designed to be used in pairs or other "arrays".

Yes, you might call the coverage "equal", but in volume only as the massive combing from combining boxes not meant to be combined will degrade the sound.  Add to that the HF reflections from the top speaker being too close to the ceiling plane and your disaster is complete.

You'll be much better off using single 300W cabinets on each side rather than the 4 x 100W pudding you've got there.  Just pick a coverage pattern that fits your space.  If you need a "downfill" for the front rows you can add them.  The B boxes you have MIGHT work for that.

As for the subs, I'll take a pass on that.  They are the least of your problems.

I won't get into the liability issues of the home-made hanging brackets........
« Last Edit: July 04, 2011, 07:36:12 pm by dick rees »
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Brad Weber

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Re: introduction & sub question
« Reply #4 on: July 04, 2011, 11:34:10 pm »

Probably just about everyone here is familiar with the budgetary and other challenges many churches face and the often creative solutions required to work within those constraints.  That being said, and with all respect for your years of "roadie/sound engineer" experience, I'm not quite sure what to make of what is shown in the pictures.
 
Perhaps we can start with the fact that a few compact 'monitor' speakers turned sideways and hung off a pipe in a vertical array using homemade rigging along with some modified full range boxes used as 'subwoofers' seems more an experiment than a well designed solution.  Seriously, I sort of doubt that a line array would be an appropriate solution for that space in any case and maybe there is some missing piece(s) of information, however not only does four vertically stacked small speakers with widely spaced drivers and little vertical pattern control not at all make a line array but those speakers were also not meant to be mounted or flown as they are.  I'm also guessing that even if all the hardware used is properly tested and rated, the rigging system is probably not.  In addition, it sounds like you may be using one channel of an unknown four channel amp to drive each array of four speakers and since the speakers are nominal 4 Ohm load then if all four are wired in parallel that's a nominal 1 Ohm load per channel, which is probably too low for the amp.
 
On the subs, bypassing any internal signal processing is not going to make a full range box a subwoofer, however it does mean that you have likely bypassed any high pass filtering and protection circuitry on the woofers, amking them more likely to be damaged.  And stacking the vents together just makes the drivers further apart and thus less likely to sum over their full range.
 
Given all this, for both safety and technical reasons you should probably get those speakers down as soon as possible and consider a more proper installed speaker system solution.  If the gear you currently have is not appropriate for the space and use then instead of making questionable modifications that likely reduce any potential resale value, think about selling the gear or using it in other spaces.
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Matthias Heitzer

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Re: introduction & sub question
« Reply #5 on: July 05, 2011, 12:41:02 pm »

I'm sure you know that this solution is...unconventional...

Most horizontal arrays of this size (and most of the "linearrays") hung in smaller installs have nothing to do with the original purpose of a linearray: to create a linesource that emits cylindrical waves.

I'd say the broad coverage of the tweeters (they have no horn) together with the reflections of the ceiling are an important reason for the success of this construction. You get so many combfilters in the HF (by the way, the woofer/squawker plays up to 5k, that's also where i guess the interference problems begin if i look at the space between the speakers in the pictures) that they might add together to something almost normal.
Definately not high end but things could be a lot worse.

To check for combilters, play a high frequency sine tone through your system and move your head a little. If the intensity changes or if the sound switches between your 2 ears, you've got comb filtering (i'm pretty sure you have, but it's hard to guess how bad it really is.)

As for the safety of your installation: the clamps you used are for water pipes (i guess your bar is) . I don't know the uk safety rules, but here in germany we need a safety factor of 12, i.e. the clamps have to be able to carry 120lbs if you want to hang 10. It looks like you've used the prexisting threads and just added the connections from one speaker to the other.
I can't judge the safety of your installation by looking at a few pictures, no one can, that's up to you and your church leadership, just remember you're responisble.

Wiring looks like 2 in series parrallel with 2 in series per side. Common 4 Ohm, nothing extrordinary and no need to worry.
If you want to continue the tinkering with the "subs" try to seal the vents. Yes, really. Below the tuning frequency there is a steep rolloff, the speaker can easily reach it's Xmax in this band.
If you make a closed sub out of it, you'll lose some low end in the first place, but boosting bass with an eq can lead to a better result in the end. Make sure to activate a highpass if your crossover has one, 50Hz won't be exaggerated.

If the lowpass is at 75 Hz, the two cabinets don't even need direct contact to couple.
You're trying to combine two fullrange speakers. the 1Cs migh need the excursion of the LF to cool their voicecoils and the HKs have very limited maximium excursion. You're between a rock and a hard place

Another, most propably better approach wold be to make a new subwoofer enclosure.
Try to find out some data about the chassis and calculate a simple BR
HK audio sometimes used the same chassis for FR and Subs, there is a slight chance yours can do both jobs
(both with compromises of course, i never understood this product design).


The 1C where at least designed for hung installation with the original bracket, the HKs and/or selfmade-sub are definately not.
Just lay the sub on one side of the stage, conceil it with a table-cloth and place a plant on top.
« Last Edit: July 05, 2011, 12:42:41 pm by Matthias Heitzer »
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Jonathan Johnson

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Re: introduction & sub question
« Reply #6 on: July 05, 2011, 07:53:29 pm »

As for the safety of your installation: the clamps you used are for water pipes (i guess your bar is) . I don't know the uk safety rules, but here in germany we need a safety factor of 12, i.e. the clamps have to be able to carry 120lbs if you want to hang 10. It looks like you've used the prexisting threads and just added the connections from one speaker to the other.
I can't judge the safety of your installation by looking at a few pictures, no one can, that's up to you and your church leadership, just remember you're responisble.

...

The 1C where at least designed for hung installation with the original bracket, the HKs and/or selfmade-sub are definately not.

Without addressing the whole liability concern of home-brew rigging, or other components in the rigging, consider that the mounting points the speakers were designed with only the weight of a single speaker in mind, plus likely dynamic forces due to vibration during use. In the installation pictured, the mounting point on the topmost speaker (not considering vectors) now bears the weight of four speakers... four times the force is being applied to this mount, so your safety factor may be diminished significantly.

Were the mounting of this array properly engineered, I would expect to see some type of beam or truss to which each speaker is individually mounted using the factory brackets; the beam/truss would then be solidly suspended from the building framing. This attachment would consider the additional load placed on the framing: in many buildings the trusses are engineered to support typical roof and snow loads, insulation, ceiling treatments, insulation, plus typical mechanical and electrical systems. When you add things such as loudspeakers to a ceiling truss system, you need to ensure that the existing load plus the additional load is within the design parameters of the ceiling truss system.

So that's why most people here won't tell you how to fly speakers on this forum, and why you'll often hear the phrase "consult a qualified rigger." There are just too many variables and calculations that we cannot provide. :-)
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Jonathan Johnson

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Re: introduction & sub question
« Reply #7 on: July 05, 2011, 07:55:18 pm »

(deleted - accidental duplication)
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biton walstra

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Re: introduction & sub question
« Reply #8 on: July 05, 2011, 08:06:40 pm »

hallo Matthias Heitzer,

vielen dank fur dein antwoord, viel besser dan von die us luite die nicht lezen kunnen.

that bar is a scaffolding pole. they are used by scaffolding companies, very strong (4mm thick). i can easily hang on it. those rods are m10 threads and those clamps are heavy stuff too. the chain i used is rated for 50kg while those 4 1c speakers are only 8kg in total. also those aluminium strips are 2mm thick. so we don't really have any worries about that.

those hk audio speakers i might flog them on ebay and build some subs as i have build many bins in the past from altec a7 / court bins / jbl 4560 / jbl 4530 to many closed and vented bins.

but we not really need to have big subs as when a band plays we only amplify vocals, guitar & keyboard. it was more that the hk audio were surplus so i changed them to use as subs. if you look at the first picture you can still see the black wall brackets just next to the projector screen. that's were they were installed when in use as full range speakers. needless to say that feedback was just around the corner with a sermon. we use a wireless clip mic.

the new 1c are sounding so much better got many compliments as "he very clear and soft sound" then those hk audio speakers as they were very harsh and thin with voice; a woofer & horn design with cheap filter.

anyway, a church with about 20 members doesn't have a big budget to buy audio gear. all the limiters, 4 channel amp, cross over and 1c speakers are bought my me as gift for the church. sure if there was a big bag with money i know exactly what to buy. but to be honest this is so much better then it was before so it's a win win for us.

funny part of this whole thread is all the negative talk about a so called line-array build from some 1c speakers... as i was actually only asking about to fly or not to fly subs... to many parrots who are not really reading / studying a post.

and as a dutch saying goes; de best stuurliu staan aan de wal.

gruss,
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Re: introduction & sub question
« Reply #9 on: July 05, 2011, 10:52:55 pm »


funny part of this whole thread is all the negative talk about a so called line-array build from some 1c speakers... as i was actually only asking about to fly or not to fly subs... to many parrots who are not really reading / studying a post.

and as a dutch saying goes; de best stuurliu staan aan de wal.

gruss,

You can have a donkey and call it a horse, but it's still a donkey.

You can put bald tires on your car and call them racing slicks, but they're still just a dangerous pipe-dream.

It's not about "flying the subs or not".  They're not subs, the suspension points are unsafe and uninsurable and the rest of your "system" is a mis-matched pile of odd components.  To answer your question does not make sense as there is just nothing right about anything you're doing.
« Last Edit: July 06, 2011, 12:50:05 am by dick rees »
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Re: introduction & sub question
« Reply #9 on: July 05, 2011, 10:52:55 pm »


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