Dear Professor Gadget...
Buzz Lightyear
Posts: 75
I would like, if you have a moment, to review the following information and either approve or disapprove of my motives and/or theories.
In my endeavors to rid the world of redundant and silly layers of unusable electronics. I have come across a venue that has (for God only knows why) the following equipment in its' rack. I will go into as much detail as possible since it is a pre-requisite within this forums' walls.
Starting at the top!
Rane ME15B (cannot recall what input levels are set at - but EQ is bypassed on both channels)
Rane SAC22 (same on input levels but that's not important at this time)
(3) QSC RMX1450 - \"280W @ 8ohm\"
Gains are set at maximum. Each amp drives two Turbosound TXD-121s in stereo. 121s are rated @ 300W RMS; 600W program, 8 ohm respectively
(2) Crown XS700 - Bridged. 118s in parallel; 4 ohm load capable of 1,900W
Gains set between 2 and 3 o'clock. Each amp drives two Turbosound TXD-118s in bridged format. 118s are rated @ 300W RMS; 600W program, 8 ohm.
(1) Crown XS1200 - Amp drives two Turbosound TXD-121s in stereo; 8-ohm per channel nominally @ 650W per channel. Again, 121s are rated @ 300W RMS; 600W program, 8 ohm
I find the gains set at varying levels from visit to visit.
My theoretical setup:
FROM the top!
Rane ME15B & SAC22
Utilizing the same gain structure technique to set input levels in this combination and once everything else falls into their place, activate the EQ and adjust in relation to venue acoustics. This of course, would be by ear as I do not have any type of RTA. The SAC22 would be set with a high-pass @ or just below 120hz.
Here's the \"fun\" part...
Since the 121s (8 in all) use four amplifiers to power them, I felt it best to kill two birds with one stone. The first of which, is making certain that the loudspeakers are used in conjunction with their corresponding RMS rating of 300W. Secondly, would be to remove any components in the chain to reduce the number of things that could break. Less 'parts', less broken things. The ultimate outcome of this idea would be to ensure that each loudspeaker will get what it requires without cooking the voice coil either in the near or distant future, I'm not going to lay anything on the line for that.
Now adding to the chain:
(1) Crown Xs1200
Stereo, 2-ohm; Each channel powering four 121s rated at 8-ohms per loudspeaker daisy-chained resulting in a 2-ohm load. Now since the amplifier is rated at 1,600-watts per channel (stereo) it is apparent that this would exceed the RMS value by 400W. Calculating would permit said overzealous amplifier to produce a total of 1,200-watts per channel. As this would be an appropriate level of power to allow the loudspeakers to do all the talking, it would also result in somewhat of a louder output during normal operation.
As it stands, the Xs1200 is obviously overpowering the loudspeakers by a good yard. Doing the math, if I wanted this amplifier to produce an output level of 1,200-watts (+/- x%) I would be able to achieve the goal of running 4 - 300-watt 8-ohm loudspeakers.
Now, according to MFGR specs, max power is achieved utilizing a 1khz tone. Given that the manuals give two different output values, the 1kHz EIA along with the 20 ~ 20kHz through the mixer (or straight through the amp - again, according to MFGR specs) would result in a larger output level at that frequency versus that of what the manual states in the 20 ~ 20kHz range. So would it be best put that if I have a 1,200-watt output level @ 1kHz that when I run music tracks (which would be within that 20 ~ 20kHz window) that I would not exceed the level which had been documented at 1kHz when playing back with full range sound?
Attaching my meter to the output lines of the amp of choice and running a 1khz signal, would eventually produce an output of approximately 48.99vac and approximately the output I am seeking. The rest would be headroom in the event of a signal spike.
The same would apply in regards to the subs being ran on the Xs700. With two TXD-118s ran in parallel, it would (theoretically) produce an ohm rating of 4-ohms and give the same parameters as the tops, a vac of 48.99 producing 750W @ 2-ohms per channel.
Proving that what it is that I have posted is relevant, employable, and nonsense free, there will only be 2 processors and 3 amps left on that rack. Not a thousand of them.
In short, two amps, 12 loudspeakers, two processing racks. No more.
Take it easy on me G, I still don't have *everything* down. I did a lot more \"back in the day\" in the industry but then again I was considerably younger.
Thanks G,
~buzz~
In my endeavors to rid the world of redundant and silly layers of unusable electronics. I have come across a venue that has (for God only knows why) the following equipment in its' rack. I will go into as much detail as possible since it is a pre-requisite within this forums' walls.
Starting at the top!
Rane ME15B (cannot recall what input levels are set at - but EQ is bypassed on both channels)
Rane SAC22 (same on input levels but that's not important at this time)
(3) QSC RMX1450 - \"280W @ 8ohm\"
Gains are set at maximum. Each amp drives two Turbosound TXD-121s in stereo. 121s are rated @ 300W RMS; 600W program, 8 ohm respectively
(2) Crown XS700 - Bridged. 118s in parallel; 4 ohm load capable of 1,900W
Gains set between 2 and 3 o'clock. Each amp drives two Turbosound TXD-118s in bridged format. 118s are rated @ 300W RMS; 600W program, 8 ohm.
(1) Crown XS1200 - Amp drives two Turbosound TXD-121s in stereo; 8-ohm per channel nominally @ 650W per channel. Again, 121s are rated @ 300W RMS; 600W program, 8 ohm
I find the gains set at varying levels from visit to visit.
My theoretical setup:
FROM the top!
Rane ME15B & SAC22
Utilizing the same gain structure technique to set input levels in this combination and once everything else falls into their place, activate the EQ and adjust in relation to venue acoustics. This of course, would be by ear as I do not have any type of RTA. The SAC22 would be set with a high-pass @ or just below 120hz.
Here's the \"fun\" part...
Since the 121s (8 in all) use four amplifiers to power them, I felt it best to kill two birds with one stone. The first of which, is making certain that the loudspeakers are used in conjunction with their corresponding RMS rating of 300W. Secondly, would be to remove any components in the chain to reduce the number of things that could break. Less 'parts', less broken things. The ultimate outcome of this idea would be to ensure that each loudspeaker will get what it requires without cooking the voice coil either in the near or distant future, I'm not going to lay anything on the line for that.
Now adding to the chain:
(1) Crown Xs1200
Stereo, 2-ohm; Each channel powering four 121s rated at 8-ohms per loudspeaker daisy-chained resulting in a 2-ohm load. Now since the amplifier is rated at 1,600-watts per channel (stereo) it is apparent that this would exceed the RMS value by 400W. Calculating would permit said overzealous amplifier to produce a total of 1,200-watts per channel. As this would be an appropriate level of power to allow the loudspeakers to do all the talking, it would also result in somewhat of a louder output during normal operation.
As it stands, the Xs1200 is obviously overpowering the loudspeakers by a good yard. Doing the math, if I wanted this amplifier to produce an output level of 1,200-watts (+/- x%) I would be able to achieve the goal of running 4 - 300-watt 8-ohm loudspeakers.
Now, according to MFGR specs, max power is achieved utilizing a 1khz tone. Given that the manuals give two different output values, the 1kHz EIA along with the 20 ~ 20kHz through the mixer (or straight through the amp - again, according to MFGR specs) would result in a larger output level at that frequency versus that of what the manual states in the 20 ~ 20kHz range. So would it be best put that if I have a 1,200-watt output level @ 1kHz that when I run music tracks (which would be within that 20 ~ 20kHz window) that I would not exceed the level which had been documented at 1kHz when playing back with full range sound?
Attaching my meter to the output lines of the amp of choice and running a 1khz signal, would eventually produce an output of approximately 48.99vac and approximately the output I am seeking. The rest would be headroom in the event of a signal spike.
The same would apply in regards to the subs being ran on the Xs700. With two TXD-118s ran in parallel, it would (theoretically) produce an ohm rating of 4-ohms and give the same parameters as the tops, a vac of 48.99 producing 750W @ 2-ohms per channel.
Proving that what it is that I have posted is relevant, employable, and nonsense free, there will only be 2 processors and 3 amps left on that rack. Not a thousand of them.
In short, two amps, 12 loudspeakers, two processing racks. No more.
Take it easy on me G, I still don't have *everything* down. I did a lot more \"back in the day\" in the industry but then again I was considerably younger.
Thanks G,
~buzz~
0
Comments
Dennis
Well Buzz...I'm going to have to punch a few holes in your balloons...
THE BIGGIE...
Stereo 8 ohm power draw both channels driven 50% duty cycle...12.5 amps
Stereo 2 ohm power draw both channels driven 50% duty cycle...30.1 amps!!
imagine the power outlet this amp is plugged into, most likely a $.50 home depot special rated @ 15 amps on a good day with a lot of help...
Second, as Dennis pointed out.. thank you Dennis...that 300 watts you so carefully calculated leaves -0- zip zilch nada... head room :shock: that 300 watt rating is pink noise all day( HIGH duty cycle on the amps...).
that 600 watt rating is normal program... aside form Death metal, most music runs in the 10-30%duty cycle area...reggae..10% Metallica 20-30% depending on the song...brief peaks of 1200 watts would easily be absorbed by this speaker...
What happens if you take a 100 watt bulb and run it @50 watts in terms of longevity? @ 50% it will last 100 times as long...Same goes for the amps...
Now take an amp driven to the max all the time...when it fails, and it will...you have nothing else in the rack to use in your scenario...no backup...
What is the purpose for the EQ? that doesn't get used? @ 15 bands it's nearly useless.. like carpet bombing when a sniper rifle will suffice!
I think you would better serve this place by examining what they are doing with what they have...like what xover point...
To me.. the Driverack replacing the EQ and Xover would be a better example of implementing the \"less is more\" rule...
Does that make sense?
Gadget 8)
What you said does make sense. I am in the business of utilizing what is in house and make it last a long time - or as long as possible.
I would like to convince the man to get a DR260 or at the least, a PA. However, it appears that they salvaged the amps, EQ, and X-over from somewhere in a closet to put the system together. That is why I looked into what they have and how it is being used and then posted it here.
The EQ is obviously doing nothing except perhaps being used to convert sexes of cables. The X-over already has input gains. So, as far as I'm concerned the EQ which is completely bypassed, is useless regardless of its' lack of features.
The only audio that is played through this system is Top 40 with some hip-hop and dance - no live bands.
So I guess what I can do now structure the mains gain-wise and then leave them be. Then, adjust the bottom cabs so where they align with the tops.
Convince the man to get a DR and if not, utilize what is there.
On a side note - and this has to do with the speakers that are on the larger amp. If for example they're \"rated\" at 600W long-term at 4ohm. The amp that I use feeds them 750W - what short or long term repercussions are at hand in this scenario? I've been informed from brand techs that the voice coil will \"just burn up\". What level or extent of validity does this have?
~B~
well you need to STOP listening to people that have no idea what they are talking about... the difference between 600 and 750 watts is negligible...in order to get twice as aloud as 500 watts you need 10 TIMES the power...
Once again for edification sake... the speakers RATED power is for PINK NOISE at 50% duty cycle or above...which means WIDE F*&*^$ OPEN all day and all night...the 'program' power is usually 2 x that.. and th4e peak power is SHORT BURST power of 3-4 times the \"rated \" power of the speaker ... SO.. if the speaker is rated @ 400 watts (that is usually free space .. which means no cabinet...speaker sitting on a table and with PINK noise pushed through it at the rated power... :shock: :shock: :shock: :shock: :shock: get the picture? Because program music (except maybe DEATH Metal) is a 10 20% duty cycle MAX type signal... and when we speak PEAK power were talking INSTANTANEOUS power (less than a part of a second in duration...)BUT the speaker CAN none the less produce several of these per minute... but not much more...
Believe me I understand \"using what you have\" to the best effort...But as I said the department of redundancy department where amps are concerned is sometimes the best way to go...
Go into the 2 ohm mode ONLY if you have something to fall back on WHEN... it fails.. it (2 ohm stereo) puts a tremendous load on the amps...
I would take MY Driverack in there and tune the crap out of the system and BLOW them away with the sound.. then and ONLY then will they even consider the Driverack...
G
I think I'll bring up the point of what I had done at one of their other venues with the DRPA it has. I'm not pro-level, but I can tell you for damn sure, I got a lot of compliments on the level and quality of the sound. You can probably do better than I can, but for arguments sake - that should be enough to get them to buy one for their second venue.
And the instantaneous peaks are things like...a snare snap, aye?
I really like this stuff, but never was shown all the things you talk about. Good thing for me, I like math and music.
Glad to hear your not falling in line...Good sound is NO accident...
more LATER...
g
You heard of the Nexia CS audio system? dbx have anything like that in their product line? I looked, the closest would be a ZC...
b
G
One of the other venues has a ZC...remember my buzz thread about the ground loop? That I could take and run the audio signal through the ZC and then signal out to the powered subs/satellites. It has it's own control panel for the desktop. Aye?
B
I have sent you a PM. Would you check it for me and get back to me? Thanks
B
Dennis
When the audio from the video is ran, the same occurs. The only problem there is no \"left\" and \"right\" input adjustment on the audio from the video system.
I contacted Nexia and I didn't get much of an answer...
:::shrugs:::
B
Dennis
G
B
g
sent you a PM about loudspeaker sound dispersal and imaging.
M
I sent you a PM with some new images.
B
In ref to our convo. If a horn has a horz dispersal of 75-deg, the vertical has one of +15/-35 (-6 db), whats that mean? EV QRX112/212, etc.
B
DRA