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[Bob Lee (QSC)]

Higher AC voltage results in more heat dissipation. Lower voltage cuts headroom but decreases heat loss.

[Phil Lewandowski]

Bob Lee (QSC) wrote on Tue, 07 October 2008 16:15

It sounds like an AC voltage issue. The usual major cause is an IR voltage drop, from drawing heavy current through wire with higher resistance than it should have. Putting a couple PLX3402 amps on a single long extension cord, driving low load impedances (especially with high duty-cycle program), will tend to cause this situation. The PLX amps will run down to 90 VAC, but below that they'll shut off after several AC cycles (faster with heavy demand, slower with light). Of course when that happens, the IR voltage drop in the AC wiring (including the extension cable) will vanish, and the voltage goes back to normal, and the amps start up again, going through their normal startup sequence. Take care of your AC issues and the problem should go away. The amps could be modified to make them less sensitive to shutting down because of poor AC, but that's like painting over a rust problem--it hides the symptom but does not cure the underlying problem.

Thanks Bob.  I am definitely going to fix any variables before the amp that could cause this problem before I give up on it!  

Phil

[Phil Lewandowski]

    So as I have stated I am planning to get some "real" AC cables for the rig.  I am planning to buy a 250ft roll of 12/3 SO from cameltraders.com.



My question is, for a weekend warrior, what lengths would you suggest cutting this up into and how many of each, to get the most efficient use of it?  I am thinking I would want 25ft and 50ft cables?

Also, how many and what lengths would you put quad boxes on?


BTW-Is there a place to buy pre-assembled Edison to Quad box 12/3 AC cable?  I am wondering because I don't think I don't think my electrician skills are up to snuff for making quad boxes!

Thanks for the advice!
Phil

[Stephen Payne]

My bet is on the dimmer source being the main problem. God only knows what that AC looked like to the amp.
If I had 250 ft of wire, I think I would make 1X125' and 2X62.5'

Good luck.

[Ken Crook]

Phil,
Before you go and trade in your PLX amps, as others have said, I would upgrade your supply cables to 10 or 12 gauge. Personally I use 10 gauge over 25'for my amp racks. Never plug into a circuit on a dimmer.

I have PLX, PLX2 and PL series amps and I have never had an amp shut-down. Sometimes I've had to put 2 bridged 3402, 1 stereo 3402 and 1 1602 on 1 20 amp circuit, however I wasn't close to running full power. Generally if more circuits are available I split that rack up 2 and 2. You just have to get a feel for how hard the system can be pushed based on power source available.

Sometimes a Poor Mans Distro means running (10 or 12ga)extension cords all over the place to get the power you need. Many venues don't have 30-50amp plugs where you need or period.

BTW check Home Depot before you have cable shipped from an online source. Also residential (Harry Homeowner) wiring books are readily available at HD which should explain and picture all you would need to know to wire a quad box. When in doubt ask though.

Ken

[Phil Lewandowski]

Ken Crook wrote on Tue, 07 October 2008 18:33

Phil, Before you go and trade in your PLX amps, as others have said, I would upgrade your supply cables to 10 or 12 gauge. Personally I use 10 gauge over 25'for my amp racks. Never plug into a circuit on a dimmer. I have PLX, PLX2 and PL series amps and I have never had an amp shut-down. Sometimes I've had to put 2 bridged 3402, 1 stereo 3402 and 1 1602 on 1 20 amp circuit, however I wasn't close to running full power. Generally if more circuits are available I split that rack up 2 and 2. You just have to get a feel for how hard the system can be pushed based on power source available. Sometimes a Poor Mans Distro means running (10 or 12ga)extension cords all over the place to get the power you need. Many venues don't have 30-50amp plugs where you need or period. BTW check Home Depot before you have cable shipped from an online source. Also residential (Harry Homeowner) wiring books are readily available at HD which should explain and picture all you would need to know to wire a quad box. When in doubt ask though. Ken

Thanks Ken, and I agree that is what I am going to do.

I did check Home Depot and they do carry both 10/3, 12/3, and 14/3 of Carol AC cable. It seemed a good amount more expensive though.  IIRC, HD had 12/3 for $86 for 100ft. The 250ft. from cameltraders.com was 12/3 Coleman AC cable for $170.  I guess I will just have to compare the price and how much shipping will be from cameltraders.


Is their a consensus that that buying 10 gauge for the amp racks would be worth the extra.  Because what I could do is just buy a smaller length of 10 gauge from HD and then 250ft online for general AC use?

Thanks!
Phil

[Phil Lewandowski]

Ken Crook wrote on Tue, 07 October 2008 18:33

Phil, Before you go and trade in your PLX amps, as others have said, I would upgrade your supply cables to 10 or 12 gauge. Personally I use 10 gauge over 25'for my amp racks. Never plug into a circuit on a dimmer. I have PLX, PLX2 and PL series amps and I have never had an amp shut-down. Sometimes I've had to put 2 bridged 3402, 1 stereo 3402 and 1 1602 on 1 20 amp circuit, however I wasn't close to running full power. Generally if more circuits are available I split that rack up 2 and 2. You just have to get a feel for how hard the system can be pushed based on power source available. Sometimes a Poor Mans Distro means running (10 or 12ga)extension cords all over the place to get the power you need. Many venues don't have 30-50amp plugs where you need or period. BTW check Home Depot before you have cable shipped from an online source. Also residential (Harry Homeowner) wiring books are readily available at HD which should explain and picture all you would need to know to wire a quad box. When in doubt ask though. Ken

Thanks Ken, and I agree that is what I am going to do.

I did check Home Depot and they do carry both 10/3, 12/3, and 14/3 of Carol AC cable. It seemed a good amount more expensive though.  IIRC, HD had 12/3 for $86 for 100ft. The 250ft. from cameltraders.com was 12/3 Coleman AC cable for $170.  I guess I will just have to compare the price and how much shipping will be from cameltraders.


Is their a consensus that that buying 10 gauge for the amp racks would be worth the extra.  Because what I could do is just buy a smaller length of 10 gauge from HD and then 250ft online for general AC use?

Thanks!
Phil

[Rob Spence]

Phil, a couple of things....

First, make sure you buy SO, SOW or SOOW cable. Much of what is in the hardware stores is SJ. Don't buy anything with a "J" in the type.

As far as lengths go, what lengths do YOU need?

I would make up some 25' #12 cables but for the long run from the far away outlet, make up a 100' #10. Sure, you can buy a 250' spool but do you really need 250' of #12 cable?

Decide what lengths of what gage you need and just buy that.

[Phil Lewandowski]

Rob Spence wrote on Tue, 07 October 2008 21:09

Phil, a couple of things.... First, make sure you buy SO, SOW or SOOW cable. Much of what is in the hardware stores is SJ. Don't buy anything with a "J" in the type. As far as lengths go, what lengths do YOU need? I would make up some 25' #12 cables but for the long run from the far away outlet, make up a 100' #10. Sure, you can buy a 250' spool but do you really need 250' of #12 cable? Decide what lengths of what gage you need and just buy that.

I will definitely buy the SO and stay away from the "Junior" as was mentioned in a past thread I read.

That is a good point.  At this point I really shouldn't need 250 ft. of power cable no matter what lengths... so it probably will be best to just stop at the local HD and buy the lengths I need.

Thanks for all the tips!
Phil

[Bob Leonard]

Phil Lewandowski wrote on Tue, 07 October 2008 21:20

Rob Spence wrote on Tue, 07 October 2008 21:09 Phil, a couple of things.... First, make sure you buy SO, SOW or SOOW cable. Much of what is in the hardware stores is SJ. Don't buy anything with a "J" in the type. As far as lengths go, what lengths do YOU need? I would make up some 25' #12 cables but for the long run from the far away outlet, make up a 100' #10. Sure, you can buy a 250' spool but do you really need 250' of #12 cable? Decide what lengths of what gage you need and just buy that. I will definitely buy the SO and stay away from the "Junior" as was mentioned in a past thread I read. That is a good point.  At this point I really shouldn't need 250 ft. of power cable no matter what lengths... so it probably will be best to just stop at the local HD and buy the lengths I need. Thanks for all the tips! Phil

Or you could do what I have done and buy extension cords that are made with the proper #12 cable and wheather proof connectors. I buy mine at a local hardware store in 25, 50 and 100 foot lengths. $50 to $125 each.