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Slipshod View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Slipshod Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2020 at 1:38pm
I got a noise complaint from across the road before the 2 subs off the KM1700 came even close to clipping. I can even run mids clear, but the minute both high and mids are connected it crackles.

Hoping it's just something silly i'm doing with the crossover, it's currently running in Stereo if that's any help.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Timebomb Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2020 at 1:57pm
The difference between 1500W into 4 ohms (77.5Vrms) and 2500W into 4 ohms (100Vrms) is 2.22dB, its not a huge amount, if 2.22dB is making you push your amps into clip then your not bringing enough rig for the gig.  You dont have to rag every last dB out of your speakers, generally it sounds better if you dont.

Imo 1-1.5x the AES driver rating is plenty, 2x is too much but you can always use a bigger amp and limit it, im not into this 2xAES thing as a "standard", can be ok for mid high but not bass and sub.

  The Colossus 18B-800 is rated at 800W AES, sqrt(800x7ohms) = 75Vrms.  That rating is in free air, so once you put it in a cabinet and restrict the airflow around the motor it will reduce the thermal handling.

Id say the XP3000H will do the job fine.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RobinMatrix Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2020 at 2:01pm
You'll have to explain more how you are linking up the mids ... 
Matrix Amplification Limited ::http://pa.matrixamplification.com/"
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 4D Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2020 at 2:09pm
Did you say Ultradrive.. ?   Nothing sounds as nasty as a dcx hitting its internal limiters. 



Try the reducing the gain on the inputs -14 is good  and raising the limiter threshold so peak output level is nowhere near activating the channel limiters  ,

If that makes sense.. 
DMZ. "The bass was intense. Girls were literally running up to stand next to the subs"
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RobinMatrix Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2020 at 2:43pm
I suspect there is some "one amp driving into another amp" or something similar going on ...eg. his mid-hi boxes are linked internally and conencting both mid and hi sockets to an amp ends up with them fighting. Something like that going on would be my guess.

Matrix Amplification Limited ::http://pa.matrixamplification.com/"
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njw View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote njw Quote  Post ReplyReply Direct Link To This Post Posted: 11 January 2020 at 10:25pm
Originally posted by Timebomb Timebomb wrote:

The difference between 1500W into 4 ohms (77.5Vrms) and 2500W into 4 ohms (100Vrms) is 2.22dB, its not a huge amount, if 2.22dB is making you push your amps into clip then your not bringing enough rig for the gig.  You dont have to rag every last dB out of your speakers, generally it sounds better if you dont.

Imo 1-1.5x the AES driver rating is plenty, 2x is too much but you can always use a bigger amp and limit it, im not into this 2xAES thing as a "standard", can be ok for mid high but not bass and sub.

  The Colossus 18B-800 is rated at 800W AES, sqrt(800x7ohms) = 75Vrms.  That rating is in free air, so once you put it in a cabinet and restrict the airflow around the motor it will reduce the thermal handling.

Id say the XP3000H will do the job fine.  
  

 Pretty much my thoughts exactly, modern music contains lots of very low frequencies and is often highly compressed, then feeding the signal through a red lining dj mixer is only going to make things worse. 1.5x AES is ample on bass imo. 
 Up until recently I was running 6x 600w 18" reflex bins on bass, one pair on a Matrix STR2000 (600w per driver) and the other two pairs on an STR3000 (750w per driver), it was only in the larger venues with a few hundred people in front of the system that I would see the occasional clip light, I wouldn't have gained any more output from larger amps, I would have definitely gained headroom but then you run the risk of things being pushed a bit harder as you have power in reserve and running the drivers into higher thermal compression.  

 Also, four of the above mentioned 18's are now in a local venue of about 200 capacity being 'underpowered' by a 1.5kw amp, I've set the limiters to just about keep the amp out of clip and they do a pretty good job of shaking the place just fine. Smile
  


Edited by njw - 11 January 2020 at 10:32pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Slipshod Quote  Post ReplyReply Direct Link To This Post Posted: 15 January 2020 at 3:26pm
Originally posted by RobinMatrix RobinMatrix wrote:

I suspect there is some "one amp driving into another amp" or something similar going on ...eg. his mid-hi boxes are linked internally and conencting both mid and hi sockets to an amp ends up with them fighting. Something like that going on would be my guess.



This is a possibility for sure, although they are bi amped MT's...I've managed to get them working but I couldn't tell you what the cause was. 

I have a whole bunch of cables, could it be that I'm using the wrong ones for the tops? As in, do I need 4 pole for bi amping and 2 pole for subs? 

I'm going to buy the Matrix 3k as a starting point, It's mainly for free parties so i'm not after event quality sound (although i'm sure any Matrix is great).
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DMorison Quote  Post ReplyReply Direct Link To This Post Posted: 16 January 2020 at 1:40pm
Originally posted by Slipshod Slipshod wrote:

Originally posted by RobinMatrix RobinMatrix wrote:

I suspect there is some "one amp driving into another amp" or something similar going on ...eg. his mid-hi boxes are linked internally and conencting both mid and hi sockets to an amp ends up with them fighting. Something like that going on would be my guess.



I have a whole bunch of cables, could it be that I'm using the wrong ones for the tops? As in, do I need 4 pole for bi amping and 2 pole for subs? 

Absolutely - if you had somehow managed to connect 2 amp channels to a 2 pole cable, you could have very easily been shorting the outputs of those 2 amps together as Robin guessed.


Edited by DMorison - 19 January 2020 at 1:30pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Slipshod Quote  Post ReplyReply Direct Link To This Post Posted: 18 January 2020 at 5:49pm
Had the guy selling me the Matrix look over my setup, both speakons are 4 pole on the back of my midtops which is why it was shorting 2 amps together, he said I will need some sort of junction box for 2, 4 pole cables to go into that then connect 4 wires onto the terminals? 

If anyone can point me in the right direction of leaning more about this sort of thing would be great!

Also discovered a rattle in 1 of my subs...still need to take the driver out to diagnose as I can't see the cone, but guessing i'll be sending it off to Fane.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote njw Quote  Post ReplyReply Direct Link To This Post Posted: 18 January 2020 at 9:16pm
Originally posted by Slipshod Slipshod wrote:

Had the guy selling me the Matrix look over my setup, both speakons are 4 pole on the back of my midtops which is why it was shorting 2 amps together, he said I will need some sort of junction box for 2, 4 pole cables to go into that then connect 4 wires onto the terminals? 

If anyone can point me in the right direction of leaning more about this sort of thing would be great!


   

 Can you post some pictures up? 
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Danielr Quote  Post ReplyReply Direct Link To This Post Posted: 21 January 2020 at 11:35pm
As an example where you might find a wiring diagram instead of the picture, I had that wiring in a pair of peavey impulse 200 speakers. I naively assumed that the speaker would only be attached to 1+ and 1- but actually it is attached to 1+ and 2+ in parallel. Same with 1/2-...

To get around this...
What I have is subs with a 4pole speakon. Wired on channel 1. And just passing through the ins to an out speakon.  Then I have a link wire where only ch2 is connected inside the speaking plugs, That way I can use a single 4core speaker cable from the amp rack to speakers, bass on ch1 mid top on ch2.

The wiring arrangement of the mid top cabinet is frustrating when you just assume it'll be wired to a single channel of the 4pole speakon. But actually not all that bad. (In my case the amp (also matrix) popped the mains fuse but lived to fight another day.) 
Once you realise the connections though it actually makes for a quite flexible setup... 

I can run a small gig using those speakers full range. with 1 amp on ch1, or a larger gig with bass on ch1 and that custom link cable for ch2. 

Just make sure you know the wiring on the output of your amp/patch panel/ speaker in future :)
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