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CDi1000/RollsRM67


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#1 kosmickuntryboy

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Posted 13 May 2012 - 09:02 PM

I have a cdi1000 with a rolls rm67 at a race track. Setup as 70v with 2-500w channels, ea channel with about 360w of atlas apx40tn's tapped accordingly. I blow about a horn a month(diaphrams) on the nearest channel, grandstands. using 2 mics on the rolls w/levels set about 2 oclock, the master set about 12 oclock. the crowns are set on the grandstand channel about 12 oclock and the far channel in the pits is set about 2 oclock. sort of new to this so where am I going wrong.

#2 dakos

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Posted 13 May 2012 - 10:37 PM

QUOTE(kosmickuntryboy @ May 13 2012, 09:02 PM) View Post
I have a cdi1000 with a rolls rm67 at a race track. Setup as 70v with 2-500w channels, ea channel with about 360w of atlas apx40tn's tapped accordingly. I blow about a horn a month(diaphrams) on the nearest channel, grandstands. using 2 mics on the rolls w/levels set about 2 oclock, the master set about 12 oclock. the crowns are set on the grandstand channel about 12 oclock and the far channel in the pits is set about 2 oclock. sort of new to this so where am I going wrong.

This is seriously wrong!!!
My first thought is that something is clipping bad or outputting DC out the mains, make sure the mixer, mic and amp are not clipping.
Are you shouting into the mic or dropping it often? How do you power on and off (do you hear a loud popping sound)?

#3 kosmickuntryboy

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Posted 13 May 2012 - 11:21 PM

QUOTE(dakos @ May 13 2012, 11:37 PM) View Post
QUOTE(kosmickuntryboy @ May 13 2012, 09:02 PM) View Post
I have a cdi1000 with a rolls rm67 at a race track. Setup as 70v with 2-500w channels, ea channel with about 360w of atlas apx40tn's tapped accordingly. I blow about a horn a month(diaphrams) on the nearest channel, grandstands. using 2 mics on the rolls w/levels set about 2 oclock, the master set about 12 oclock. the crowns are set on the grandstand channel about 12 oclock and the far channel in the pits is set about 2 oclock. sort of new to this so where am I going wrong.

This is seriously wrong!!!
My first thought is that something is clipping bad or outputting DC out the mains, make sure the mixer, mic and amp are not clipping.
Are you shouting into the mic or dropping it often? How do you power on and off (do you hear a loud popping sound)?

No. I have seen clipping at times usually with an announcer that shouts at the action and I will turn up the mains(crown?)and the clip light ceases. the crown was padded on the software at 3db. I have the 2 crown vol set at about 10 am on the grandstand channel(A) and set at 12 oclock on the pit channel(cool.gif. We sequence power downs and power ups as per instructions. amp 1st on pwr off and rev order on pwr up. the only loud pop that blew a diaphram was when the owner plugged up xm radio w/3.5mm plug and then jerked it out and caused a loud pop.

#4 dakos

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Posted 14 May 2012 - 01:39 PM

QUOTE(kosmickuntryboy @ May 13 2012, 11:21 PM) View Post
No. I have seen clipping at times usually with an announcer that shouts at the action and I will turn up the mains(crown?)and the clip light ceases.
the crown was padded on the software at 3db.

I don't understand what you did here, did you activate a -3dB limiter?

QUOTE(kosmickuntryboy @ May 13 2012, 11:21 PM) View Post
I have the 2 crown vol set at about 10 am on the grandstand channel(A) and set at 12 oclock on the pit channel(cool.gif. We sequence power downs and power ups as per instructions. amp 1st on pwr off and rev order on pwr up. the only loud pop that blew a diaphram was when the owner plugged up xm radio w/3.5mm plug and then jerked it out and caused a loud pop.

The absolute position of the gain knobs, on the amp or on the mixer, don't ensure that you don't clip, it doesn't even lower the maximum power of the amp or the maximum signal out of the mixer, all it does is lower the gain. Think of it like this, if it took 1V (volt) of music at the input of the amp to get the maximum power when the gain is open all the way, then if you dial it back 50% (12 oclock) then it would take 2V at the amps input to get maximum power out of it, that's all the gain knobs do. One more thing, it doesn't matter where in the sound chain the clipping occured, in the mixer, in the amp, for all the speaker cares is whether there is clipping or not. So I need to ask you again, how often do you see the clip lights on the amp blinking? how about on the mixer?

It might be wise to install a compressor especially for unpredictable occasonal shouter, do you have one available?

What speakers do you have? are more getting fried on the pits or in the grandstand? high frequency drivers getting fried or low frequency drivers?

#5 kosmickuntryboy

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Posted 14 May 2012 - 02:22 PM

QUOTE(dakos @ May 14 2012, 02:39 PM) View Post
QUOTE(kosmickuntryboy @ May 13 2012, 11:21 PM) View Post
No. I have seen clipping at times usually with an announcer that shouts at the action and I will turn up the mains(crown?)and the clip light ceases.
the crown was padded on the software at 3db.

I don't understand what you did here, did you activate a -3dB limiter?

QUOTE(kosmickuntryboy @ May 13 2012, 11:21 PM) View Post
I have the 2 crown vol set at about 10 am on the grandstand channel(A) and set at 12 oclock on the pit channel(cool.gif. We sequence power downs and power ups as per instructions. amp 1st on pwr off and rev order on pwr up. the only loud pop that blew a diaphram was when the owner plugged up xm radio w/3.5mm plug and then jerked it out and caused a loud pop.

The absolute position of the gain knobs, on the amp or on the mixer, don't ensure that you don't clip, it doesn't even lower the maximum power of the amp or the maximum signal out of the mixer, all it does is lower the gain. Think of it like this, if it took 1V (volt) of music at the input of the amp to get the maximum power when the gain is open all the way, then if you dial it back 50% (12 oclock) then it would take 2V at the amps input to get maximum power out of it, that's all the gain knobs do. One more thing, it doesn't matter where in the sound chain the clipping occured, in the mixer, in the amp, for all the speaker cares is whether there is clipping or not. So I need to ask you again, how often do you see the clip lights on the amp blinking? how about on the mixer?

It might be wise to install a compressor especially for unpredictable occasonal shouter, do you have one available?

What speakers do you have? are more getting fried on the pits or in the grandstand? high frequency drivers getting fried or low frequency drivers?

I have never seen a clip lite on the amp. What clipping I have seen has always been at the mixer and only a "light" flashing indication. the horns that blow are over the grandstand which are nearer. I have some horns that are radio shack 8ohm w/30v transformers tapped at 30v. they never blow. the atlas apx40tn's are always the culprits. they are tapped at 40w. the scoring tower is a bustle of activity during a race so I'm not always able to monitor the equip like I need to I guess. I appreciate you assistance immenslely.

#6 dakos

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Posted 14 May 2012 - 02:57 PM

QUOTE(kosmickuntryboy @ May 14 2012, 02:22 PM) View Post
I have never seen a clip lite on the amp. What clipping I have seen has always been at the mixer and only a "light" flashing indication. the horns that blow are over the grandstand which are nearer. I have some horns that are radio shack 8ohm w/30v transformers tapped at 30v. they never blow. the atlas apx40tn's are always the culprits. they are tapped at 40w. the scoring tower is a bustle of activity during a race so I'm not always able to monitor the equip like I need to I guess. I appreciate you assistance immenslely.

I see those Atlas horns have a voltage selectors, did you select 70V? how many horns do you have connected?

The problem could also be due to cone over excursion so set a high pass filter on your CDi's DSP for 400hz at 24 dB/octave L/R. you might need to connect the amp to a computer with System Architect for that.

You could avoid mishaps such as what your boss did if you get a rack mixer that has high pass filters such as the Mackie Onyx 800R or the Yamaha MLA8.