A question for you P.A. experts...

[Jesso]

Hey folks,

I'm looking for opinions about our P.A. setup.

Here's what we have at the moment....

[url="http://www.dynacord.de/en/products/7/1/1/7_powersub315.html"]http://www.dynacord.de/en/products/7/1/1/7_powersub315.html[/url]

Also we have the passive sister of this sub, which means each sub is getting 500 watts. (all powered from the 2K dynacord amp in the DLITE 115 sub)

My first question is: Is it ok to clip this amp?
I find that our set-up is loud enough most of the time, but in the big rooms, to get the volume I want I need to clip the amp.
It's only the sub that is clipping, not the tops. And it's only clipping on the kick drum notes.
If it's safe enough to clip this amp a bit, then I don't need to beef up the P.A.

Wadda you reckon? Does anyone have any experience with DYNACORD amps like this?

Jesse

[TomTFS]

[quote name='Jesso' post='934036' date='Aug 23 2010, 07:06 PM']Hey folks,

I'm looking for opinions about our P.A. setup.

Here's what we have at the moment....

[url="http://www.dynacord.de/en/products/7/1/1/7_powersub315.html"]http://www.dynacord.de/en/products/7/1/1/7_powersub315.html[/url]

Also we have the passive sister of this sub, which means each sub is getting 500 watts. (all powered from the 2K dynacord amp in the DLITE 115 sub)

My first question is: Is it ok to clip this amp?
I find that our set-up is loud enough most of the time, but in the big rooms, to get the volume I want I need to clip the amp.
It's only the sub that is clipping, not the tops. And it's only clipping on the kick drum notes.
If it's safe enough to clip this amp a bit, then I don't need to beef up the P.A.

Wadda you reckon? Does anyone have any experience with DYNACORD amps like this?

Jesse[/quote]

Generally clipping the amp is bad. You shouldn't be TOO damaging running it like that but it may wear the system out over time.

If you've got a graphic eq over the system try pulling out some of the lowest frequencies (you can probably roll off everything below 31.5 at least) as those speakers wont reproduce them to a great degree anyway. This way you are only sending frequencies that your speakers can actually reproduce, thus giving you more headroom.

[Jesso]

[quote name='TomTFS' post='934048' date='Aug 23 2010, 07:16 PM']Generally clipping the amp is bad. You shouldn't be TOO damaging running it like that but it may wear the system out over time.

If you've got a graphic eq over the system try pulling out some of the lowest frequencies (you can probably roll off everything below 31.5 at least) as those speakers wont reproduce them to a great degree anyway. This way you are only sending frequencies that your speakers can actually reproduce, thus giving you more headroom.[/quote]

Thanks. I actually already have an eq on my master channel for the DJing (a software EQ) so I've taken out almost everything below 40hz but it's still clipping.
Clipping the amp is worse for the speaker than the amp I've read, but is that true?
It's not audible clipping at all. It sounds bloomin great when it's clipping, pumping out some very sweet balanced low end.

[Bill Fitzmaurice]

Clipping is never good. It doesn't really bother the amp but will sooner or later toast the driver if the amp is capable of pushing the driver past either its thermal or mechanical limits.
I'd be willing to be that you have the subs incorrectly placed, ie., split to either side, beneath the tops. Most operators do it that way, as subs don't come with placement instructions. Worse still are those with pole sockets that encourage that placement. The right way is explained here. The link specifically refers to horns, but all subs adhere to the same rules of placement.
[url="http://billfitzmaurice.info/forum/viewtopic.php?f=1&t=398&sid=3fb065f1be520fc61efeaf0adcd7ddea"]http://billfitzmaurice.info/forum/viewtopi...efeaf0adcd7ddea[/url]

Edited August 23, 2010 by Bill Fitzmaurice

[Ian Savage]

[quote name='Jesso' post='934159' date='Aug 23 2010, 08:48 PM']Clipping the amp is worse for the speaker than the amp I've read, but is that true?[/quote]

As a general rule that is true, because amplifier clipping introduces large amounts of high-frequency harmonics into the signal, which can fry tweeters in a very short space of time.
If you've got the user manual for the system have a look at what level the clip lights on the amplifier are set to come on at; if (as is the case with most amps) they're set to come on a few dB before you hit the maximum signal level that the amp can put out you're probably okay to have them flashing BRIEFLY on signal peaks, particularly if it's only the subwoofer amps which are clipping as obviously these won't have tweeters in the to fry with high-frequency clipping distortion!

Do keep tabs on the temperature of the amps as you're running them to be on the safe side; if they're too hot to touch after thirty minutes to an hour of working you'll need to beef up the system, if they're only warm you're alright.

[Jesso]

Thanks for answering.
I have heard several times that it's better to place the subs together, but from an asthetic and stability point of view, putting the subs either side of the stage with the mid/high speakers on-top makes much more sense....
We often play to boozed up crowds, and manys the time I've been glad that our speakers are very steadily held by the subs. i.e. some drunk eejit bashing into a normal speaker stand usually has very serious results!

Wouldn't putting the subs to one side of the stage be strange from a sound point of view?
If it's a very wide stage, people on one side of the dance floor are getting tons of bass, while on the other side it's taking the bass a bit longer to arrive and when it does it's not as loud?

Just to confirm.... I'm not clipping the amp running the tweeters, so I know that I won't damage the tops.
It's just the subs that are getting clipped a bit.
The amp isn't getting too hot at all, just warm, so I don't think I'm running it into the ground or anything...

I was reading about the subs we have, here's what it says....

[quote]The cabinet is equipped with an electronic circuit called VOICE COIL TRACKING PROTECTION. This circuit senses the terminal voltage of the transducer and simulates the thermal behaviour of the woofer´s voice coil. In case of potential thermal overload the power applied to the speaker is reduced to a safe level. Extremely powerful amps can be used in order to have maximum dynamic range without the danger of thermal overload in non-controlled situations. The VOICE COIL TRACKING PROTECTION exhibits “soft” switching characteristics, so no annoying clicks or pops are audible[/quote]

Which gives me some peace of mind...... The subs are rated at 1600 watts peak, and I know the power amp is only feeding them 500 watts each.... although as far as I know I can still damage them even with 500 watts.

I can't see anything about what level the clip lights are set to come on at... but maybe I'm missing something? Here's the spec page:

[url="http://www.dynacord.de/en/products/7/1/1/5_sub115.html"]http://www.dynacord.de/en/products/7/1/1/5_sub115.html[/url]

Somebody told me that dynacord overengineer everything, so I can be pretty sure that unless I'm clipping the hell out of it, it's safe enough.
Still though, it goes against my insticnts to see a red light coming on on every kick drum hit!

Thanks guys for going to the bother of helping out with this. I'm not very technical when it comes to this kind of thing so I really appreciate your input.

Jesse

[Bill Fitzmaurice]

[quote name='Jesso' post='934302' date='Aug 23 2010, 06:21 PM']Thanks for answering.
I have heard several times that it's better to place the subs together, but from an asthetic and stability point of view,
Jesse[/quote]The choice is simple: do you want to look good or sound good? Where subwoofer placement is concerned more often than not it's a distinct choice between the two.
[quote]Wouldn't putting the subs to one side of the stage be strange from a sound point of view?[/quote]No. Neither should they be away from walls, neither should they be pointed at the audience. This is admittedly all counter-intuitive, but the field of acoustics is very much counter-intuitive. Proper versus improper sub placement can account for as much as a 24dB difference in output. That's the equivalent of 10 watts versus 2000 watts.

Edited August 24, 2010 by Bill Fitzmaurice

[Jesso]

[quote name='Bill Fitzmaurice' post='934368' date='Aug 24 2010, 03:30 AM']The choice is simple: do you want to look good or sound good? Where subwoofer placement is concerned more often than not it's a distinct choice between the two.
No. Neither should they be away from walls, neither should they be pointed at the audience. This is admittedly all counter-intuitive, but the field of acoustics is very much counter-intuitive. Proper versus improper sub placement can account for as much as a 24dB difference in output. That's the equivalent of 10 watts versus 2000 watts.[/quote]

That is a total head melter....
So in most cases the audience may not even see the subs at all? They could be behind the stage, or off to the side, where ever there is a wall? I'll try it some day when we have extra time for setting up our equipment.
They are front ported subs. Should the ports be facing the wall?
Thanks Bill you obviously know a lot about this stuff, so I'm taking it all on board!
I'll show this thread to my band mates... otherwise they'd never believe me!

[crez5150]

I absolutely agree with what Bill is saying but in most cases this solution is unsuitable for small to mid size bands. Most bands would have a sub/sat arrangement as this is the easiest and most sensible solution for this type of set up.

I guess Jesse it depends on what you call a big room.....

[Jesso]

[quote name='crez5150' post='934470' date='Aug 24 2010, 09:33 AM']I absolutely agree with what Bill is saying but in most cases this solution is unsuitable for small to mid size bands. Most bands would have a sub/sat arrangement as this is the easiest and most sensible solution for this type of set up.

I guess Jesse it depends on what you call a big room.....[/quote]

Well, on Sunday night the room was the size of an aircraft hanger! Maybe that's a slight exaduration, but certainly there was room for about 4 full sized tennis courts plus seating!
There were 200 at the wedding, but they seemed quite lost in a room that size.
Every few weeks we get a big room like that. Rarely do they have enough people at the wedding to justify the size of the room!
How do you find the K-array system? I've heard one (the 4k one) in a shop over here, (Ireland) but I'd love to actually get a demo for a while!
Sounded great in the shop.

[crez5150]

Hmmm we have similar situations with weddings. The key is to have the PA Just cover the Dance area. No real need to blast the whole room. THe K-Array is a fantastic system... we have three of them now and they really are very versatile.

We also use an LD Premium Line array for larger events which is really portable and excellent projection for larger rooms.

[Bill Fitzmaurice]

[quote name='Jesso' post='934461' date='Aug 24 2010, 04:25 AM']So in most cases the audience may not even see the subs at all? They could be behind the stage, or off to the side, where ever there is a wall?[/quote]Yes. The output of subs is omnidirectional, so there's no need to see them. That's quite the opposite of tops, which are very directional. Dispersion and boundary loading characteristics below 100Hz versus above 100 Hz are completely different, so much so that if your subs and tops are in the same room location chances are about 20:1 that the results will be compromised, often severely so.