6BG6 - come on, relax.
If I read the original poster correctly, this is a utility ballroom in a hotel, not a concert venue. This is the sort of room that is configured for a sales meeting one day, and a family reunion the next. The stages are risers set up for the particular needs of the day, so he has been asked to provide for them in two places.
The whole point of a ceiling speaker array is that one or two speakers will be over any listener. This is not the same as a main speaker system at the end of the hall serving the entire audience. SO for a lecture room, delay lines and multiple amps is way overkill.
If I read the original poster correctly, this is a utility ballroom in a hotel, not a concert venue. This is the sort of room that is configured for a sales meeting one day, and a family reunion the next. The stages are risers set up for the particular needs of the day, so he has been asked to provide for them in two places.
The whole point of a ceiling speaker array is that one or two speakers will be over any listener. This is not the same as a main speaker system at the end of the hall serving the entire audience. SO for a lecture room, delay lines and multiple amps is way overkill.
Enzo
Just wondering if that 40 yrs is in the commercial sound field designing and installing equipment or is it in your sound repair shop?
There is a difference and from my experience every little audio shop out there thinks they are the experts in sound design and installation. Sorry but if I had a dollar for every mistake I have repaired or corrected I wouldn't have to work. What I stated is the best in design for the uses of that room. The ability to switch to different parts of the room and have the system be correct. Any idiot can and usually does install a blanket system in this case and expects it to work flawlessly and I'm sorry to inform you of this but they don't. I surely do understand that the rooms, ballrooms, banquet, meeting, or what ever the heck you want to call them have needs and these needs have to be satisfied so that the end result will be flawless. I cannot do a system that will result in ones ability not to be able to understand what the speaker is saying. I have done probably thousands of these systems and generally cost is not a consideration but usefulness of the system and the systems ability to provide to the people that come in for their conventions and such is. My experience is the completely flawless systems are the ones that are booked and the others of questionable design sit unused 50-60% of the time. .
Just wondering if that 40 yrs is in the commercial sound field designing and installing equipment or is it in your sound repair shop?
There is a difference and from my experience every little audio shop out there thinks they are the experts in sound design and installation. Sorry but if I had a dollar for every mistake I have repaired or corrected I wouldn't have to work. What I stated is the best in design for the uses of that room. The ability to switch to different parts of the room and have the system be correct. Any idiot can and usually does install a blanket system in this case and expects it to work flawlessly and I'm sorry to inform you of this but they don't. I surely do understand that the rooms, ballrooms, banquet, meeting, or what ever the heck you want to call them have needs and these needs have to be satisfied so that the end result will be flawless. I cannot do a system that will result in ones ability not to be able to understand what the speaker is saying. I have done probably thousands of these systems and generally cost is not a consideration but usefulness of the system and the systems ability to provide to the people that come in for their conventions and such is. My experience is the completely flawless systems are the ones that are booked and the others of questionable design sit unused 50-60% of the time. .
OK,
So the basics. The reverb time of the room is a maximum of around 2.65 seconds at 500 Hz. It drops to .77 seconds at 4K. 250 - 2.42, 1K - 1.42, 2K - .87.
This is going to be a "Tubby" room. Equalization will not fix that. People and furniture will. However those are variables and not the same for every use. So draperies on the walls are the best choice.
Next is SPL for the intended use. Loud multipurpose rooms would be 95 db. You can get away with as low as 85. These are average levels so add about 15 db minimum for peak levels. That is a minimum of 100 db. The loss from the loudspeaker at 4m high to ear level between two loudspeakers would be 15 db. so you require 115 db out of each loudspeaker. A ceiling speaker might do about 92 db per watt, so you need 23 db of power per loudspeaker. That is 200 watts per loudspeaker.
Now look at coverage of ten loudspeakers. A decent real coverage angle at HF is +/- 45 degrees so each loudspeaker will cover an area of 25 sq M if everyone places their ears on the floor. Using a more reasonable height of 1.25 M (seated ears) would give a coverage of 12 sq M per loudspeaker. The room area is 264 sq M so 22 loudspeakers would be required to cover. Of course now you can get away with 100 watts per loudspeaker.
Now you can use two delay lines to feed an amplifier matrix feeding the loudspeakers. That way you can put the signal into one delay for the left wall and the other delay for the front.
So in reality. Be sure there are always curtains in the room. Use the maximum transformer tap on the loudspeakers in the room. Play music and walk around turn down the HF until it sounds uniform all over. Put is about 3 db of cut from 200 to 800 Hz.
So the basics. The reverb time of the room is a maximum of around 2.65 seconds at 500 Hz. It drops to .77 seconds at 4K. 250 - 2.42, 1K - 1.42, 2K - .87.
This is going to be a "Tubby" room. Equalization will not fix that. People and furniture will. However those are variables and not the same for every use. So draperies on the walls are the best choice.
Next is SPL for the intended use. Loud multipurpose rooms would be 95 db. You can get away with as low as 85. These are average levels so add about 15 db minimum for peak levels. That is a minimum of 100 db. The loss from the loudspeaker at 4m high to ear level between two loudspeakers would be 15 db. so you require 115 db out of each loudspeaker. A ceiling speaker might do about 92 db per watt, so you need 23 db of power per loudspeaker. That is 200 watts per loudspeaker.
Now look at coverage of ten loudspeakers. A decent real coverage angle at HF is +/- 45 degrees so each loudspeaker will cover an area of 25 sq M if everyone places their ears on the floor. Using a more reasonable height of 1.25 M (seated ears) would give a coverage of 12 sq M per loudspeaker. The room area is 264 sq M so 22 loudspeakers would be required to cover. Of course now you can get away with 100 watts per loudspeaker.
Now you can use two delay lines to feed an amplifier matrix feeding the loudspeakers. That way you can put the signal into one delay for the left wall and the other delay for the front.
So in reality. Be sure there are always curtains in the room. Use the maximum transformer tap on the loudspeakers in the room. Play music and walk around turn down the HF until it sounds uniform all over. Put is about 3 db of cut from 200 to 800 Hz.
From post #1 dimensions and surface materials. The equations are well known.
You can even find free calculators on the web!
I'm with Pano, never had an issue with a decent DI box and PC causing hum. And I'm not just agreeing because he's a mod too, but based on lots of practical experience.
6BG6, I am not going to get into a p***ing contest with you. I'm no kid in a basement.
The hotel has asked their employee to design a system for them, that doesn;t sound like cost is no object to me. That sounds like "we want it cheap."
MY experience is in live sound, as well as many years designing and installing sound systems in restaurants and bars, yes most based upon 70.7v distribution and ceiling speakers. Not to mention 8 years in broadcasting.
I see this utility room project as for spoken word or background music. Any bands or wedding DJs will be bringing their own sound systems, certainly they're not going to rely on his ceiling speaker array.
Since there will be no main speaker stack at the stage in his setup, when you add delay to some speakers, what will you delay them with respect to? Each audience member will be listening to the speaker over his head.
The hotel has asked their employee to design a system for them, that doesn;t sound like cost is no object to me. That sounds like "we want it cheap."
MY experience is in live sound, as well as many years designing and installing sound systems in restaurants and bars, yes most based upon 70.7v distribution and ceiling speakers. Not to mention 8 years in broadcasting.
I see this utility room project as for spoken word or background music. Any bands or wedding DJs will be bringing their own sound systems, certainly they're not going to rely on his ceiling speaker array.
Since there will be no main speaker stack at the stage in his setup, when you add delay to some speakers, what will you delay them with respect to? Each audience member will be listening to the speaker over his head.
Whoa, dude. Chill out! I thought they had a sense of humor in Iowa.
Nothing I posted was meant to offend, quite the contrary. I apologize if that wasn't clear. In no way was I trying to disparage your work or knowledge. Sorry you read that into it. It was all meant in good humor and good fun.BTW, if you don't see a cop hat, then it is not a moderator posting. Just a post from another forum member. That is true for all moderators.
If you don't wish to help the OP, that's understandable, it's what you get paid for, no need to give it away. There are others here who can help.
6BG6GA, I totally see where you are coming from. However, based on the info given I think the assumption is that this hotel has minimal A/V support.
Ether, please correct me if I'm way off base there.
There's a good chance it's either maintenance or custodial staff that are charged with setting up the risers and plugging the mic in the wall. If a remote panel was installed to recall presets of a delay line processor, chances are it would rarely if ever be touched and the delay zones would do more harm than good.
I've done systems both ways with good results. I think it's all about the bigger picture.
(Since we're tossing around credentials, look up large sound companies in Yonkers NY and that will give you an idea where I'm coming from)
Ether, please correct me if I'm way off base there.
There's a good chance it's either maintenance or custodial staff that are charged with setting up the risers and plugging the mic in the wall. If a remote panel was installed to recall presets of a delay line processor, chances are it would rarely if ever be touched and the delay zones would do more harm than good.
I've done systems both ways with good results. I think it's all about the bigger picture.
(Since we're tossing around credentials, look up large sound companies in Yonkers NY and that will give you an idea where I'm coming from)
Well gentlemen what I suggested is how I would have done it given the chance and a usable budget.
As for the RT 60 times based on a program.... my experience has been that sometimes they are correct but most times they aren't correct. I take equipment to measure RT 60 times.
Enzo,
I would use the first row of speakers by the stage at no delay and start delaying each row as I moved away from the first or primary row of speakers. This way one seems to have the illusion that the sound is coming from the front instead of getting hit first from the speakers above your head and then from the speakers in the row ahead of that and so forth. Experience has taught me that this method works far better that just throwing up a 70.7 volt line of speakers and paralleling them all together. Granted delaying them for music like background Muzak in a different mode of operation would be of no value what so ever.Some do not add delay lines as I will call them when using ceiling speakers. Delay is not just used when employing speakers on stands up front or speakers on stages.
If the budget isn't there then throw up the 70.7 volt speakers with no delays. I would however suggest a decent EQ like a Shure DFR22 to eq and to set feedback filters. However the amount of speakers suggested by the poster needs to be doubled in order to have some decent coverage with some overlap. I do suggest the 70 volt speakers over using 8 ohm with a series parallel config. Note the 8 ohm speakers would require much much larger wire or smaller gauge that what the 70 volt system would. With the 70 volt one could easily get by with 18 ga wire.
As for the RT 60 times based on a program.... my experience has been that sometimes they are correct but most times they aren't correct. I take equipment to measure RT 60 times.
Enzo,
I would use the first row of speakers by the stage at no delay and start delaying each row as I moved away from the first or primary row of speakers. This way one seems to have the illusion that the sound is coming from the front instead of getting hit first from the speakers above your head and then from the speakers in the row ahead of that and so forth. Experience has taught me that this method works far better that just throwing up a 70.7 volt line of speakers and paralleling them all together. Granted delaying them for music like background Muzak in a different mode of operation would be of no value what so ever.Some do not add delay lines as I will call them when using ceiling speakers. Delay is not just used when employing speakers on stands up front or speakers on stages.
If the budget isn't there then throw up the 70.7 volt speakers with no delays. I would however suggest a decent EQ like a Shure DFR22 to eq and to set feedback filters. However the amount of speakers suggested by the poster needs to be doubled in order to have some decent coverage with some overlap. I do suggest the 70 volt speakers over using 8 ohm with a series parallel config. Note the 8 ohm speakers would require much much larger wire or smaller gauge that what the 70 volt system would. With the 70 volt one could easily get by with 18 ga wire.
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So let's recap:
That should give you some good points going forward. We don't know how much room you have in your money and time budget to change things. Knowing that would help us help you.
- Everyone agrees that you should use a 70V or 100V system. Either will be fine, use what is current practice in your location.
- The Amp you chose can do either 70V or 100V. That's good.
- The speaker lines have been pulled. No problem, you can still use the 70/100V speakers. You'll need a panel where all the speakers lines come together.
- Forget stereo, just run the system mono.
- Use zones. If you can turn off or attenuate the speakers above the active stage, so much the better.
- 10 speakers will be the bare minimum to cover your area.
- EQ is a good idea.
- Delay could also be a good idea, but may not be in the budget (extra amps, delay units)
- Get some sort of DI, transformer or interface to connect computers to the mixing console via the installed mic lines.
That should give you some good points going forward. We don't know how much room you have in your money and time budget to change things. Knowing that would help us help you.
Quote:
Get some sort of DI, transformer or interface to connect computers to the mixing console via the installed mic lines.
Direct box for interface from mic jack at stage for computer, line source
Something like the Edcor to connect a computer to the mix at head end via Aux input on board or line in on a channel.
Get some sort of DI, transformer or interface to connect computers to the mixing console via the installed mic lines.
Direct box for interface from mic jack at stage for computer, line source
Something like the Edcor to connect a computer to the mix at head end via Aux input on board or line in on a channel.
I use these at work. Very $$ though. Never a problem with them.
Radial Engineering - ProDI / ProD2 passive direct boxes
Radial Engineering - ProDI / ProD2 passive direct boxes
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