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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: Robert Weston on February 22, 2011, 08:06:07 pm

Title: Amplifier supplied power-cords
Post by: Robert Weston on February 22, 2011, 08:06:07 pm
When you purchase an amplifier new, they usually come with a power cord.  Do you all use the provided power cords with your amplifier(s)?  Or do you opt for something a bit larger/robust?

All of my amplifier power cords are UL 14AWG 3-conductor SJT (most are manufactured by Ching Cheng).  All my amplifiers are QSC (2502's, 3402's, 3602's).

Are there other cords available that are better to use than these?  I've never had any issues with these (none that I'm aware of), but considering the QSCs need a good amount of service power, wasn't sure if these cords have caused me some "outage" issues in the past.



Title: Re: Amplifier supplied power-cords
Post by: Rob Spence on February 23, 2011, 12:26:03 am
I am more likely to choose which cord to use based on the length I need.
For my amp racks I don't need a 2 meter cord so I leave the factory one at home. As for wire gage? I use 14 or 12 for most large power consumers and 16 for the most part every where else.
Note: This is about IEC cords, not feeders.
Title: Re: Amplifier supplied power-cords
Post by: No Name on February 23, 2011, 01:08:30 am
+1
I use custom length cables in all my racks.  Using 2m cables when you only need 500mm just leads to messy racks and should be avoided.  I use 1.5mmx3 H07RN-F Lineax cable for all internal power patching.  Slight overkill maybe, but it keeps everything neat and easy to manage.
Title: Re: Amplifier supplied power-cords
Post by: Robert Weston on February 23, 2011, 07:22:09 am
Thanks guys -

The extension power cords I use are all SOOJ 10/3 from "the wall" to the rack (25' and 50' lengths).  Then from those cords (10/3) they connect to the factory supplied cords (14/3).  The supplied cords are all about 4ft to 5ft in length.  There's plenty of room in the rack to store them.

Without much analysis and basic guess-work, I'm assuming a 5ft section of 14/3 may not be starving the amplifiers of too much current.

Even though, perhaps shorter amp. power cords would still be better.


Title: Re: Amplifier supplied power-cords
Post by: George Dougherty on February 23, 2011, 11:22:23 am
I picked up replacement Edison ends from a local hardware store and customized the length of my included power cords.  In my rack I have both mains and monitor amps so I used the colored variety to give me a visual indicator of which was which.  It's nice having all the same manufacturer as they tend to standardize the power inlet location (left vs right) and I bundled all the cables neatly up the side of the amp rack up to the pair of Furman units I have at top to give me voltage metering on my input circuits.  Signal cable bundled on the other side of the rack down to my custom jack panel.

Voltage drop is a function of distance and gauge combined.  A short length of 14ga is perfectly fine, just as it is for speaker cable.  Yes, you want a large gauge to minimize voltage drop on a long feeder run.
Title: Re: Amplifier supplied power-cords
Post by: Tim McCulloch on February 23, 2011, 11:36:22 am
Thanks guys -

The extension power cords I use are all SOOJ 10/3 from "the wall" to the rack (25' and 50' lengths).  Then from those cords (10/3) they connect to the factory supplied cords (14/3).  The supplied cords are all about 4ft to 5ft in length.  There's plenty of room in the rack to store them.

Without much analysis and basic guess-work, I'm assuming a 5ft section of 14/3 may not be starving the amplifiers of too much current.

Even though, perhaps shorter amp. power cords would still be better.

The AWG of the provided power cord is not an issue.  You won't be "starving" an amp for power.  Do you not think the manufacturer would reject a wire gauge that wouldn't allow the amp to meet specs?
Title: Re: Amplifier supplied power-cords
Post by: Robert Weston on February 23, 2011, 09:43:21 pm
Not that a manufacture would provide a sub-quality cord, but more of would a larger wire size provide more benefit than just meeting specs.

Looks like I'll keep the 14 AWG cord in service.


Title: Re: Amplifier supplied power-cords
Post by: Tom Fletcher on February 26, 2011, 09:56:01 am
Are there other cords available that are better to use than these?

I recently purchased some IEC cords from monoprice.com - they offer 14, 16, and 18 AWG cords in a variety of lengths and configurations. I was skeptical because of the "too good to be true" prices, but I was pleased with the quality when they arrived. The 18 gauge versions are UL listed (or they've done a really good job of faking the sticker :D).

I won't go so far as saying that these are "better" - I replaced the stock cords for the purpose of cleaning up the tangle in my rack, not for any performance issue.  I used 14 gauge for amps and 18 gauge for everything else.
Title: Re: Amplifier supplied power-cords
Post by: chuck clark on February 27, 2011, 06:57:30 pm
This issue is at the BOTTOM of my worries list.  At or near the top of my "non-issue" list.
However I wish I had a dollar for everytime I've had trouble w/ an IEC cord coming loose in the back of a rack. I would like to meet the guy who invented the IEC cord so I can kick him in the butt hard enough to lift his heels a couple inches off the ground for all the extra trouble and headache. GREAT now a regular extension cord won't work AND they come loose alot. Nothing like constant improvement. THANX butthead!
Exactly how these became "de riguer" is a miracle of idiocy I frankly do not understand. (end rant)
Chuck
Title: Re: Amplifier supplied power-cords
Post by: Mike McNany on February 28, 2011, 07:27:32 am
GREAT now a regular extension cord won't work AND they come loose alot. Nothing like constant improvement. THANX butthead!
Exactly how these became "de riguer" is a miracle of idiocy I frankly do not understand. (end rant)
Chuck

IMHO, it's from the "global economy". Easier to swap out a different cordset for different countries, with or without changes to the internal power supply.

Yeah, I, too, have a couple items, usually in the amp racks (ampS and DRPA) that like to lose their AC power cables.

Mike McNany
Title: Re: Amplifier supplied power-cords
Post by: Geoff Doane on February 28, 2011, 09:46:35 am
This issue is at the BOTTOM of my worries list.  At or near the top of my "non-issue" list.
However I wish I had a dollar for everytime I've had trouble w/ an IEC cord coming loose in the back of a rack. I would like to meet the guy who invented the IEC cord so I can kick him in the butt hard enough to lift his heels a couple inches off the ground for all the extra trouble and headache. GREAT now a regular extension cord won't work AND they come loose alot. Nothing like constant improvement. THANX butthead!
Exactly how these became "de riguer" is a miracle of idiocy I frankly do not understand. (end rant)
Chuck

We've been down this road before on the old forum.  Apparently, in order to meet safety regulations, if the line cord is permanently attached, it has to support the weight of the amp without pulling out, OR you can make it detach without breaking anything, hence the IEC connector.  QSC (and more recently EV) has started using locking IECs on their equipment (I suspect they will part without damage if you apply enough force).

As for wire gauge, get out a resistance chart, and do a comparison.  An 18 inch, 18 ga. IEC cord has less resistance than a 4 ft., 14 ga. cord.  And it's the resistance that counts.  My amps are older, and don't have the locking IECs, so a ty-rap to the rear rack ear keeps the cords secure.

GTD
Title: Re: Amplifier supplied power-cords
Post by: George Dougherty on February 28, 2011, 11:31:31 am
This issue is at the BOTTOM of my worries list.  At or near the top of my "non-issue" list.
However I wish I had a dollar for everytime I've had trouble w/ an IEC cord coming loose in the back of a rack. I would like to meet the guy who invented the IEC cord so I can kick him in the butt hard enough to lift his heels a couple inches off the ground for all the extra trouble and headache. GREAT now a regular extension cord won't work AND they come loose alot. Nothing like constant improvement. THANX butthead!
Exactly how these became "de riguer" is a miracle of idiocy I frankly do not understand. (end rant)
Chuck

Had the same annoyance so I made mine friction fit.  A narrow section of gaffer's tape just wide enough to cover the length of the IEC connector that fits into the socket and wrapped enough times around that it takes a bit of effort to get the plug into the socket did the trick.  My amp rack now goes anywhere without a need to reseat the cords at each stop.  The friction fit is tight enough to keep it in place, but still allows for removal when necessary.  The tape will compress a bit over time with repeated use so I do need to add another small section to a monitor amp that gets occasionally unracked for small gigs, but that's a quick fix.
Title: Re: Amplifier supplied power-cords
Post by: Bob Leonard on March 02, 2011, 09:08:28 am
We've been down this road before on the old forum.  Apparently, in order to meet safety regulations, if the line cord is permanently attached, it has to support the weight of the amp without pulling out, OR you can make it detach without breaking anything, hence the IEC connector.  QSC (and more recently EV) has started using locking IECs on their equipment (I suspect they will part without damage if you apply enough force).

As for wire gauge, get out a resistance chart, and do a comparison.  An 18 inch, 18 ga. IEC cord has less resistance than a 4 ft., 14 ga. cord.  And it's the resistance that counts.  My amps are older, and don't have the locking IECs, so a ty-rap to the rear rack ear keeps the cords secure.

GTD

Correct on all counts.
 
If you buy an amp and it comes with the cord it will have to be UL approved in this country. I have never found a need to do anything more than to neatly tuck the access into the rack, out of the way beside the amp. Everything else to me is a waste of my time and money.  ;)