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Which Amps for the Job


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#1 DoctorDavid

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Posted 17 April 2012 - 08:44 PM

I need a little help picking a few amps to drive my line array. Each cabinet contains the following components.
I plan on jumping two boxes together, and using one half of a XTI4002 to drive (LF section)of the two boxes, of
course the other half will drive another two boxes. My dilemma is what to do with the HF section. Do I go with
the XTI1002? Lastly I would like to keep about 6db of head room.


LF section 210"(260mm) neodymium woofer LF 500W(RMS)1000W(PEAK)(8 ohms) per box

HF section 22"neodymium compression driver HF 160W(RMS)320W(PEAK)(16 ohms) per box

Crown has never let me down in the past, So, I though I would see what you guys suggest. If I'm
totally wrong, thats fine.....You guys know what will work best.

David

#2 dakos

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Posted 18 April 2012 - 05:49 AM

QUOTE(DoctorDavid @ Apr 17 2012, 08:44 PM) View Post
I need a little help picking a few amps to drive my line array. Each cabinet contains the following components.
I plan on jumping two boxes together, and using one half of a XTI4002 to drive (LF section)of the two boxes, of
course the other half will drive another two boxes. My dilemma is what to do with the HF section. Do I go with
the XTI1002? Lastly I would like to keep about 6db of head room.


LF section 2?10"(260mm) neodymium woofer LF 500W(RMS)1000W(PEAK)(8 ohms) per box

HF section 2?2"neodymium compression driver HF 160W(RMS)320W(PEAK)(16 ohms) per box

Crown has never let me down in the past, So, I though I would see what you guys suggest. If I'm
totally wrong, that's fine.....You guys know what will work best.

David

It would help a bit to find out what other gear you have, do you have more amps or just that 4002 for now? Can you specify the exact box name and model instead of the specs alone? I think your numbers are a bit off (either 2000W peak or 250W RMS). What do you use for processing?

1002 could work but it wouldn't give you the headroom you want.

Nowadays amps have almost no headroom in them while speaker still do, Especially the budget series amps like the XTI. So to get the headroom you want (+6dB) you need an amp about 4 times the RMS wattage of the speakers. This would be OK to use the maximum amp output for short bursts (headroom) but NOT for continuous music.

Here is a great article that explains everything in detail.

#3 DoctorDavid

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Posted 18 April 2012 - 09:44 PM

Thanks for your reply. First question, I'm running (4) 4002 in bridge mode on my subs. I need to purchase enough amps to drive (8)line array boxes per side.
Oh I will be adding some extra sub also, but not at this time. I have priced every line array made both here in the US and Europe, and was surprised to find
that there was not one company able to supply a small sound company with a mid sized line array system, that could be used out side and in 2000-3500 seat in door
venue. And when I said looked I don't mean a casual glance around the net, I mean a year or more pricing, comparing both new and used. So what I've come
up with is a manufacture of line array systems in China(no wonder there are no jobs in the USA). This is the web site link directly to the product. When your
looking at the specs, make sure you look at the W-210A, array. There are 2 sets of specs listed one for a W-210, and the W-210A. Hope this will shed a little more light
on what I'm trying to do.

http://cvr-audio.en.alibaba.com/product/45...ray_system.html

And you may be thinking Hmmm....What about TVi Audio, been there. (2)-10" and a 1.75 driver 1799.00 each

dakos hope this helps.

David



QUOTE(dakos @ Apr 18 2012, 06:49 AM) View Post
QUOTE(Doctor David @ Apr 17 2012, 08:44 PM) View Post
I need a little help picking a few amps to drive my line array. Each cabinet contains the following components.
I plan on jumping two boxes together, and using one half of a XTI4002 to drive (LF section)of the two boxes, of
course the other half will drive another two boxes. My dilemma is what to do with the HF section. Do I go with
the XTI1002? Lastly I would like to keep about 6db of head room.


LF section 2?10"(260mm) neodymium woofer LF 500W(RMS)1000W(PEAK)(8 ohms) per box

HF section 2?2"neodymium compression driver HF 160W(RMS)320W(PEAK)(16 ohms) per box

Crown has never let me down in the past, So, I though I would see what you guys suggest. If I'm
totally wrong, that's fine.....You guys know what will work best.

David

It would help a bit to find out what other gear you have, do you have more amps or just that 4002 for now? Can you specify the exact box name and model instead of the specs alone? I think your numbers are a bit off (either 2000W peak or 250W RMS). What do you use for processing?

1002 could work but it wouldn't give you the headroom you want.

Nowadays amps have almost no headroom in them while speaker still do, Especially the budget series amps like the XTI. So to get the headroom you want (+6dB) you need an amp about 4 times the RMS wattage of the speakers. This would be OK to use the maximum amp output for short bursts (headroom) but NOT for continuous music.

Here is a great article that explains everything in detail.



#4 dakos

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Posted 18 April 2012 - 11:38 PM

QUOTE(DoctorDavid @ Apr 18 2012, 09:44 PM) View Post
Thanks for your reply. First question, I'm running (4) 4002 in bridge mode on my subs. I need to purchase enough amps to drive (8)line array boxes per side.
Oh I will be adding some extra sub also, but not at this time. I have priced every line array made both here in the US and Europe, and was surprised to find
that there was not one company able to supply a small sound company with a mid sized line array system, that could be used out side and in 2000-3500 seat indoor venue. And when I said looked I don't mean a casual glance around the net, I mean a year or more pricing, comparing both new and used. So what I've come up with is a manufacture of line array systems in China (no wonder there are no jobs in the USA). This is the web site link directly to the product. When your looking at the specs, make sure you look at the W-210A, array. There are 2 sets of specs listed one for a W-210, and the W-210A. Hope this will shed a little more light on what I'm trying to do.

http://cvr-audio.en.alibaba.com/product/45...ray_system.html

And you may be thinking Hmmm....What about TVi Audio, been there. (2)-10" and a 1.75 driver 1799.00 each

dakos hope this helps.

David

Well, my best guess is that they are speccing their speakers differently from what I'm used to, I have to play it safe and consider their 1000W peak as the true number, that means I will treat them as being 250W RMS. Since they are 16 ohm boxes, and you need a 6dB headroom, you need allot of power, 1000W per box, 8 boxes per side, that's 8000W amp per side peak, either the ITech 6000, 8000, 9000 or the 12000 can provide that, the MAi 9000 or 12000 will also do a great job. You need to connect 4 boxes per channel to get a total of four ohms.

Did you mean using XTIs for the job?

#5 DoctorDavid

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Posted 19 April 2012 - 09:09 PM

dokos, thank you for taking the time to review and answer my questions. Lastly, the XTi 2 series is likely more in my price range for amps at this time.
Is there a way to use the XTi 2 series. I was thinking that maybe a 4002 in bridged mode would do(XTi-2 8 ohms bridged 2400 watts) (2) boxes, but then again I'm stuck with what to do
on the HF side. Do you have any thoughts or added suggestions, using the XTi-2 series?

David


QUOTE(dakos @ Apr 19 2012, 12:38 AM) View Post
QUOTE(Doctor David @ Apr 18 2012, 09:44 PM) View Post
Thanks for your reply. First question, I'm running (4) 4002 in bridge mode on my subs. I need to purchase enough amps to drive (8)line array boxes per side.
Oh I will be adding some extra sub also, but not at this time. I have priced every line array made both here in the US and Europe, and was surprised to find
that there was not one company able to supply a small sound company with a mid sized line array system, that could be used out side and in 2000-3500 seat indoor venue. And when I said looked I don't mean a casual glance around the net, I mean a year or more pricing, comparing both new and used. So what I've come up with is a manufacture of line array systems in China (no wonder there are no jobs in the USA). This is the web site link directly to the product. When your looking at the specs, make sure you look at the W-210A, array. There are 2 sets of specs listed one for a W-210, and the W-210A. Hope this will shed a little more light on what I'm trying to do.

http://cvr-audio.en.alibaba.com/product/45...ray_system.html

And you may be thinking Hmmm....What about TVi Audio, been there. (2)-10" and a 1.75 driver 1799.00 each

dakos hope this helps.

David

Well, my best guess is that they are speccing their speakers differently from what I'm used to, I have to play it safe and consider their 1000W peak as the true number, that means I will treat them as being 250W RMS. Since they are 16 ohm boxes, and you need a 6dB headroom, you need allot of power, 1000W per box, 8 boxes per side, that's 8000W amp per side peak, either the ITech 6000, 8000, 9000 or the 12000 can provide that, the MAi 9000 or 12000 will also do a great job. You need to connect 4 boxes per channel to get a total of four ohms.

Did you mean using THIs for the job?



#6 dakos

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Posted 19 April 2012 - 11:04 PM

QUOTE(DoctorDavid @ Apr 19 2012, 09:09 PM) View Post
dakos, thank you for taking the time to review and answer my questions. Lastly, the XTi 2 series is likely more in my price range for amps at this time.
Is there a way to use the XTi 2 series. I was thinking that maybe a 4002 in bridged mode would do(XTi-2 8 ohms bridged 2400 watts) (2) boxes, but then again I'm stuck with what to do
on the HF side. Do you have any thoughts or added suggestions, using the XTi-2 series?

David

Using XTIs is not a problem it just means using allot of XTIs,
For the LF 4 x 4002 or 2 x 6002 per side.
For the HF 2 x 2002 per side.

I do think that using MAi for the LF drivers is better and the 9000 will cost just a little more.

#7 DoctorDavid

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Posted 21 April 2012 - 10:42 AM

Hi dakos, well I've made my decision. I found some new XTi-6002 B stock amps at a more than fare price so, I will be going with those.
Fininally the last question. Would these be running in bridge mode or stero mode, the same applys for the 2002.
Thanks for all your help.

David

QUOTE(dakos @ Apr 20 2012, 12:04 AM) View Post
QUOTE(DoctorDavid @ Apr 19 2012, 09:09 PM) View Post
dakos, thank you for taking the time to review and answer my questions. Lastly, the XTi 2 series is likely more in my price range for amps at this time.
Is there a way to use the XTi 2 series. I was thinking that maybe a 4002 in bridged mode would do(XTi-2 8 ohms bridged 2400 watts) (2) boxes, but then again I'm stuck with what to do
on the HF side. Do you have any thoughts or added suggestions, using the XTi-2 series?

David

Using XTIs is not a problem it just means using allot of XTIs,
For the LF 4 x 4002 or 2 x 6002 per side.
For the HF 2 x 2002 per side.

I do think that using MAi for the LF drivers is better and the 9000 will cost just a little more.



#8 dakos

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Posted 21 April 2012 - 11:15 AM

QUOTE(DoctorDavid @ Apr 21 2012, 10:42 AM) View Post
Hi dakos, well I've made my decision. I found some new XTi-6002 B stock amps at a more than fare price so, I will be going with those.
Fininally the last question. Would these be running in bridge mode or stero mode, the same applys for the 2002.
Thanks for all your help.

David

Dear David,
I'm sorry, I double checked my calculations now and I think I got something wrong, the 6002 is NOT a good option, all the rest are still valid. The wattage adds up just fine but you quoted the wrong impedance sad.gif the HF driver AND the LF driver are both 16 ohms.

So the new and improved plan is this:
The 4002 bridged into two parallel boxes, 16 ohms per box, 8 ohms total, 2400 watts, using the limiter to limit the amp to 2000W will give the desired 1000W peak per box.
The 4002 parallel mono, each channel into 4 parallel HF drivers, 16 ohm each, 4 ohm total per channel impedance, 1200W total per channel gives 300W peak per HF box.
You could also use the 2002 for the HF drivers but you would need to use more amps.
So that's 5 4002 per side. This shouldn't effect the total system cost since 2x4002 cost almost the same as 1x6002.
Again, sorry for the confusion.

#9 dakos

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Posted 23 April 2012 - 08:40 AM

QUOTE(DoctorDavid @ Apr 21 2012, 10:42 AM) View Post
Hi dakos, well I've made my decision. I found some new XTi-6002 B stock amps at a more than fare price so, I will be going with those.
Finally the last question. Would these be running in bridge mode or stero mode, the same applys for the 2002.
Thanks for all your help.

David

Just so to make sure so there are no more mistakes, can you please check the actual speakers impedance?


#10 DoctorDavid

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Posted 23 April 2012 - 08:17 PM

QUOTE(dakos @ Apr 23 2012, 09:40 AM) View Post
QUOTE(Doctor David @ Apr 21 2012, 10:42 AM) View Post
Hi dakos, well I've made my decision. I found some new XTi-6002 B stock amps at a more than fare price so, I will be going with those.
Finally the last question. Would these be running in bridge mode or stereo mode, the same applies for the 2002.
Thanks for all your help.

David

Just so to make sure so there are no more mistakes, can you please check the actual speakers impedance?


dakos,
Yesterday I ordered (4) of those line array boxes. They will becoming DHL, so I should have them, by the end of the week, and the first place to start is
to check the speaker impedance. So, for now It looks like we will be at a stand still until they arrive, but better safe than sorry.

David

#11 dakos

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Posted 23 April 2012 - 11:04 PM

Great smile.gif

#12 DoctorDavid

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Posted 25 April 2012 - 09:08 PM

dakos, I finally received my request from tech services on the speaker in the array boxes.

2- 10" 8 ohm speaker wired in series giving 16 ohms total for LF
2- 2" 8 ohm driver again wired in series giving 16 ohms total for the HF

So, it looks like you were right on with the.

So the new and improved plan is this:
The 4002 bridged into two parallel boxes, 16 ohms per box, 8 ohms total, 2400 watts, using the limiter to limit the amp to 2000W will give the desired 1000W peak per box.
The 4002 parallel mono, each channel into 4 parallel HF drivers, 16 ohm each, 4 ohm total per channel impedance, 1200W total per channel gives 300W peak per HF box.
You could also use the 2002 for the HF drivers but you would need to use more amps.

I think the last thing is how much -db to dial up on the limiter, -5db or -10db to decrease the amp to 2000 watts.

#13 dakos

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Posted 26 April 2012 - 12:45 AM

QUOTE(DoctorDavid @ Apr 25 2012, 09:08 PM) View Post
dakos, I finally received my request from tech services on the speaker in the array boxes.

2- 10" 8 ohm speaker wired in series giving 16 ohms total for LF
2- 2" 8 ohm driver again wired in series giving 16 ohms total for the HF

So, it looks like you were right on with the.

So the new and improved plan is this:
The 4002 bridged into two parallel boxes, 16 ohms per box, 8 ohms total, 2400 watts, using the limiter to limit the amp to 2000W will give the desired 1000W peak per box.
The 4002 parallel mono, each channel into 4 parallel HF drivers, 16 ohm each, 4 ohm total per channel impedance, 1200W total per channel gives 300W peak per HF box.
You could also use the 2002 for the HF drivers but you would need to use more amps.

I think the last thing is how much -db to dial up on the limiter, -5db or -10db to decrease the amp to 2000 watts.

When configuring the limiters using the front panel then the XTIs limiter takes dBfs units and not dB or dBu, the maximum power output of the XTI is 2400W, that equals 0 dBfs. Your speakers are rated at 2000W peak, from here it's just a plain dB ratio formula, you get:
10 X Log(P1/P2)=10XLog(2000/2400)= -0.8 dBfs

Alternatively you can use System Architect for this, I imagine you'll start using it at some point, then you can input the maximum voltage directly:
If P is the power limit in watts, Z is the driver's nominal impedance in ohms, and G is the amplifier gain in dB (not dBu!), the limiter threshold in dBu is just 10*log(P*Z/0.6)-G, the math is pretty simple once you have the data.