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Multiple amps in same freq band

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bassmish View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bassmish Quote  Post ReplyReply Direct Link To This Post Posted: 29 July 2008 at 12:28pm
right so you're saying that there shouldn't be any large depreciation in signal unless unbalanced cable is used? Then I guess it's prob cos I use mostly unbalanced cable!!
 
does a balanced jack cable use a stereo plug? I guess not because it is only mono on an xlr to jack but this is balanced?
 
thanks for the info regarding the inputs as links in some cases on amps, could be very useful.
 
One more Q; when there is a link on an amp, is this just a parallel connection to the input? (so if there isn't a link available one can be created)
the current must decrease as more amps are added then so why is this not a problem?
 
cheers
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Post Options Post Options   Thanks (0) Thanks(0)   Quote HMSS Quote  Post ReplyReply Direct Link To This Post Posted: 06 August 2008 at 1:02am
You could buy one of these ultra link from Beringher
I use one sometimes to split signals and control gain etc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote colinmono Quote  Post ReplyReply Direct Link To This Post Posted: 06 August 2008 at 10:42am
Originally posted by bassmish bassmish wrote:

does a balanced jack cable use a stereo plug? I guess not because it is only mono on an xlr to jack but this is balanced?


Yes, balanced jack connections use stereo plugs. +ve signal (pin 2 on XLR) goes to tip, -ve signal (pin 3 of XLR) goes to the first ring, and ground (pin 1 on XLR) goes to the second ring (sleeve).

This article explains all:

http://en.wikipedia.org/wiki/TRS_connector#Tip.2Fring.2Fsleeve_terminology

Originally posted by bassmish bassmish wrote:

One more Q; when there is a link on an amp, is this just a parallel connection to the input? (so if there isn't a link available one can be created)
the current must decrease as more amps are added then so why is this not a problem?


When you have a link input on an amp channel both the main input and the "link" are simply connected inside the amp. A Y cable can be used to split the signal to two amps where no link connection is available.

You are correct in thinking that the signal level will drop as more amps are connected, but in practice (I think due to the relationship between the output impedance of the crossover to the input impedance of the amps), the drop is small and this will not cause you any problems unless you are linking a large number of amps together.

There is a big difference in level between a balanced and an unbalanced signal (6dB IRC), so switching to an all balanced setup should help if you're having trouble giving your amps a large enough signal.


Edited by colinmono - 06 August 2008 at 10:44am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote chickenfizz Quote  Post ReplyReply Direct Link To This Post Posted: 20 August 2008 at 1:19pm
Just to quickly add to what has been said, because almost always the links on amps are simply paralell splits this means that if you use an unbalanced connector anywhere between any of the amps then the whole chain will be unbalanced.

Connecting many amps to one output shouldn't be a problem, for example the output impedance of the Behringer DCX is 160 ohms, the input impedance of an MC2 E series amp is 20,000 ohms. If you connect 12 channels of amp to the one input you still have a load of more than 10 times the output (1666 ohms) you could in this kind of case send this signal down a long multicore without problems too. Following this 'ten times is a good number' rule then you have a theoretical safe maximum of 72 channels of amp that the DCX is capable of driving. I think this is conservative though.

The only time there may be a problem is if you were using completely different amps and one had an imput impedance of say 20k ohms and the other was 2k ohms, in this case the amp with the 2k ohm input would get a larger proportion of the signal, but the difference would be very small unless a very large number of amps were being used or a high impedance output (with inherantly poor line driving capability) was used.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote adambomb Quote  Post ReplyReply Direct Link To This Post Posted: 26 August 2008 at 12:11am
I have had problems linking amps as described above... I think this is probably down the architecture of my amps rather than the above info being wrong.
 
The second amp in the chain would always be slightly down on gain (even the signal lights on the front of the amps confirmed this, first one in the chain would always start flashing first, tried swapping the amps around, different cables etc etc)... in the end I just made up a Y-Cable.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pfly Quote  Post ReplyReply Direct Link To This Post Posted: 05 November 2008 at 3:12am
One thing I've been thinking of would be the case of driving similar cabs with different amps.

Let's say I'd use a Proline 2700 in 4ohm bridged to drive two 1850 horns, and say Tapco J2500 to drive another pair of 1850 horns in 4ohm bridged.

Now how does this affect their coupling? Different amps may have really different damping factors and all other values.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sawyer Quote  Post ReplyReply Direct Link To This Post Posted: 09 December 2008 at 9:56am
I'm having an issue with this now. I've got a Matrix STR 1500 which daisy chains into 2 Bheringer 1500 in bridged mode. (Using XLR > XLR) The Matrix isnt even hitting -6db (2nd light up I think) but the Bheringer is clipping! The only way I can stop if from clipping is obviously turning the volume down on the amp, which I obviously don't want to do.
Whats the best way to resolve this? How would I go about making on of those split cables from out of the Crossover? Which pins to which?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote yardie Quote  Post ReplyReply Direct Link To This Post Posted: 09 December 2008 at 12:56pm

this may have more to do with gain structure than frequency.If you go to Rane.com rane notes you can find out how to make up cables.

hope this helps
i got the sound bug bad there no cure
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Post Options Post Options   Thanks (0) Thanks(0)   Quote andyamp Quote  Post ReplyReply Direct Link To This Post Posted: 17 January 2009 at 6:30pm
how old is the str1500?
a wise man changes his mind a fool does not.
http://www.matrixamplification.com/
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Post Options Post Options   Thanks (0) Thanks(0)   Quote demanddeepbass Quote  Post ReplyReply Direct Link To This Post Posted: 04 March 2009 at 3:37pm
note that not all amps are the same sensitivity. some give full output from 0.775volts of input some from 1.4volts and there are some other odd ones in between. Quite a few amps have a "sensitivity" switch on the back or sometimes an internal jumper. Make sure they are all set the same or one amp of the same power may be quite a lot quieter than another.

Id also like to point out that there is no such such thing as a stereo jack plug! occasionally people attempt to put two channels through a balanced jack plug but this is not as god intended and should be avoided.... a bit like using XLRs for speakers. LOL let the flame grilling begin ;-)


Edited by demanddeepbass - 04 March 2009 at 3:44pm
"These amps go up to 11"
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bassmish View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bassmish Quote  Post ReplyReply Direct Link To This Post Posted: 10 June 2009 at 2:00am
Originally posted by demanddeepbass demanddeepbass wrote:


Id also like to point out that there is no such such thing as a stereo jack plug! occasionally people attempt to put two channels through a balanced jack plug but this is not as god intended and should be avoided.... a bit like using XLRs for speakers. LOL let the flame grilling begin ;-)


why?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote demanddeepbass Quote  Post ReplyReply Direct Link To This Post Posted: 10 June 2009 at 11:29am
The Jack Plug is one of the most misused connectors going. They get used for unbalanced stereo signals, unbalanced mono connections, balanced mono connections, headphones, loudspeaker connections, insert points and occasionally even power connections. All of which causes huge amounts of confusion. Can you imagine what would happen when Johnny guitarist plugs the speaker output of his 3000watt guitar head into your lovely Midas mixer? It's probably similar to what happens when you swear at him pull the plug out and drop it on the metal stage when it shorts, gives him a shock and blows up his amp.
The point is you are never quite sure what is on the end of a jack cable unless you can find the other end which sucks. The same used to be true of XLRs to a lesser extent till the speakon came along. Thankfully XLRs on speakers are very rare now. (although 3 pin XLRs for DMX are much more common now (this is due to lazy lampies not bringing enough 5 pin cable to the gig and wanting to steal your mic cables for DMX))
Professionals should use balanced or unbalanced 1/4" jack plugs with line level signals on them. If its a patch panel it probably makes sense to use a B gauge jack. Putting unbalanced stereo down one cable just causes confusion. If you plug it into a mono balanced input the CMR amplifier will probably null most of the signal. One exception with 1/4" jacks (which is by convention and irritates me greatly!) is headphones. Another (which is an irritating desk manufacturers cost saving measure) is unbalanced insert points.
This is all perfectly clear in my little OCD world and should be in everyone elses!

/end rant.
"These amps go up to 11"
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