Power cords

[agedhorse]

I actually took that into account! I used to work with a bunch of industrial electrical design and field engineers and was always bugging them with questions. But there aren't many Class D amps in a power plant, so it was unfamiliar territory for them.

Yes, class D amps are usually only found in the break room.

However, many power supplies for process control, and even to some extent VFD’s use some of the same principles.

 

[clockworkcorpse]

Hey @agedhorse, I understand the use of the word "continuous" as used by cec/nec, but i've often been curious about amplifiers (like aguilar) that rate outputs as "continuous". in this case, the tone hammer 700 claims the ability to continuously produce an output of 700 watts, but because while in use our playing is not continuous, should we consider the 700 as peak?

 

[seamonkey]

I'm always happy to follow the manufacturers advice while it is in the warranty period especially for power cords since there is No after market power cord that could ever do better than the one supplied.

I wouldn't mind buying replacement cords from the original manufacturer. Some of the IEC connectors are just bad fits, and who knows how well they are crimped, and the quality of the terminals. The physical weight of the cable matters too. If if thick and heavy insulation it may not stay so well in the iec jack just from gravity pulling down. The manufacture knows all the specs of the jacks and cables they use.

But manufacturers need to do a better job of identifying their cables and cords. Put a label on them, even a tie wrap one, and keep a chart online of the specs.

 

[Jefenator]

Glad I found this thread. I've settled on 10' as a desirable length (so don't always have to run power right to the base of my speakers) but the 14AWG I've been using barely fits in the amp bag.

 

[logdrum]

No h, cords not chords. Ah got it. And no audiophile snake oil about thousand dollar 3 foot AC cords. Back to my hole....

 

[agedhorse]

Hey @agedhorse, I understand the use of the word "continuous" as used by cec/nec, but i've often been curious about amplifiers (like aguilar) that rate outputs as "continuous". in this case, the tone hammer 700 claims the ability to continuously produce an output of 700 watts, but because while in use our playing is not continuous, should we consider the 700 as peak?

Good question, peak is a different term when applies to an audio signal.

The term continuous is almost certainly based on using the “RMS” output power for greater than a few seconds (far longer than the “20mSec burst” that some manufacturers use). The “peak” power (based on peak voltage not RMS voltage) would be 1400 watts peak. This is true of every amplifier rated at 700 watts RMS.

 

[TomB]

I like a 10-gauge for goose, but for most other critters, I find that a 12-gauge is sufficient.

I dunno… 10 for rabbits maybe?

 

[SoCal80s]

Thanks @agedhorse , this is a very informative thread. I've been wanting to upgrade my (class D) powered speaker PA mains which are rated at 800W to new ones rated at 2000W and I was worried that I'd be popping fuses since at most clubs you're lucky if you have two outlets on the "stage".

 

[byacey]

I just use the power cords that came with the product, use appropriately gauged extensions if necessary when gigging, and try to keep them as short as is practical. And I’ve never once had a problem. Am I alone in that?

It doesn't hurt to use a heavier extension cord, especially if it's of any appreciable length. The wire resistance of #18 adds up to a considerable amount if run over any distance, especially if the same extension cord is used to power any other devices, simultaneously.
A #16 cable's safe current handling is roughly equal to two #18s, or a #14 is equal to four #18s.

 

[OogieWaWa]

VFD’s use some of the same principles

Heh, we only had two with switching. They drove 25Hp motors, lol. And a AC/DC/AC motor generator set, 250Hp! Our one big constant voltage supply, 150KVA, used a movable core transformer with a small motor to change the turns ratio! All the new stuff is fully digital.

 

[clockworkcorpse]

Good question, peak is a different term when applies to an audio signal.

The term continuous is almost certainly based on using the “RMS” output power for greater than a few seconds (far longer than the “20mSec burst” that some manufacturers use). The “peak” power (based on peak voltage not RMS voltage) would be 1400 watts peak. This is true of every amplifier rated at 700 watts RMS.

just a quick follow up question... if the example amp also has a max power consumption rating of 835 watts, does that change anything?

 

[agedhorse]

Thanks @agedhorse , this is a very informative thread. I've been wanting to upgrade my (class D) powered speaker PA mains which are rated at 800W to new ones rated at 2000W and I was worried that I'd be popping fuses since at most clubs you're lucky if you have two outlets on the "stage".

This is a good question… and the answer is going to be somewhat confusing because of this particular market.

The power rating of most powered PA speakers is highly misleading, and the marketing guys got their way with the engineers on this part.

Often, the power here is stated as peak, or if RMS is highly managed to insure that the speakers are not damaged Also, if bi-amped, the high frequency amp will be limited to prevent damage by either using a smaller amp, by using a 16 ohm high frequency driver, with dynamics management (limiting) or a combination of the 3 methods. A HF driver will always be limited to less than 50 watts RMS average continuous (and usually less than 30 watts) because that’s what the drivers themselves are capable of.

Just beware that you aren’t comparing apples to oranges here.

 

[agedhorse]

just a quick follow up question... if the example amp also has a max power consumption rating of 835 watts, does that change anything?

Good question. It depends on how that rating is defined…

Generally, the maximum power consumption would be with a duty cycle of 100%, which is impractical for an audio signal. If you were to take the same amp and measure it at a lower duty cycle, the power consumption would decrease roughly proportionally.

The regulations state that the minimum stated power consumption can be no lower than 12.5% (1/8-rated audio power). The number can be stated as higher however.

 

[agedhorse]

Heh, we only had two with switching. They drove 25Hp motors, lol. And a AC/DC/AC motor generator set, 250Hp! Our one big constant voltage supply, 150KVA, used a movable core transformer with a small motor to change the turns ratio! All the new stuff is fully digital.

I used to work on large M-G sets for electroplating, the G side was rated at 5000 amps at about 5VDC. There were 48 brushes about 1-1/2” square on a commutator 24” in diameter!

 

[byacey]

Heh, we only had two with switching. They drove 25Hp motors, lol. And a AC/DC/AC motor generator set, 250Hp! Our one big constant voltage supply, 150KVA, used a movable core transformer with a small motor to change the turns ratio! All the new stuff is fully digital.

Was this changing the turns ratio, or the core reactance? If the turns ratio was changing, it would be more of a variac setup.

 

[BlueTalon]

I think I'd be somewhat more concerned about the ampacity of that power strip and cord that all has all those loads shown plugged in on the OP's post. Some loads really do use their rated current.

I just plugged those in for the photo, but your point remains.

 

[LonesomeKris]

I find as I age that a three hour gig with a 12 gauge power cord is just too much for my back. I’m selling all my cords and settling for a 24 gauge short scale

 

[byacey]

I recently was selecting IEC power cords in a most unorthodox manner. I stopped in at my dad's place a few weeks ago, and I found him in the garage, one of his usual places. He had a huge box of IEC power cords, and he was hard at work chopping the ends off the cords.

It seems a friend of his who had retired from the military gave him a box of cords, among some other junk, so he picked out what he wanted, and was going to cash the rest in for scrap copper. Fortunately, I arrived before he was halfway through the box, and I fished out some very nice power cords that were made in Switzerland, and had very nice, supple insulation on them.

One of my beefs with many of these cheaper cables, is the hard thermoplastic insulation that even in hot weather does not flex very well, and in cold weather becomes downright rigid. These Swiss cables probably were supplied with some premium gear, and are very flexible indeed.

 

[TheReceder]

I recently was selecting IEC power cords in a most unorthodox manner. I stopped in at my dad's place a few weeks ago, and I found him in the garage, one of his usual places. He had a huge box of IEC power cords, and he was hard at work chopping the ends off the cords.

It seems a friend of his who had retired from the military gave him a box of cords, among some other junk, so he picked out what he wanted, and was going to cash the rest in for scrap copper. Fortunately, I arrived before he was halfway through the box, and I fished out some very nice power cords that were made in Switzerland, and had very nice, supple insulation on them.

One of my beefs with many of these cheaper cables, is the hard thermoplastic insulation that even in hot weather does not flex very well, and in cold weather becomes downright rigid. These Swiss cables probably were supplied with some premium gear, and are very flexible indeed.

I'd inspected Test equipment while in the military, make sure you ohm out the cables as some of the cords typically will have open connections (usually in the ground wire). I don't know how many I'd thrown out that read an open. To me that's the biggest reason to get quality IEC cables. The most common failure is the one you'll never see.

 

[Jefenator]

Glad I found this thread. I've settled on 10' as a desirable length (so don't always have to run power right to the base of my speakers) but the 14AWG I've been using barely fits in the amp bag.

Found a 16AWG and, what do you know: it fits way better!

I recently was selecting IEC power cords in a most unorthodox manner. I stopped in at my dad's place a few weeks ago, and I found him in the garage, one of his usual places. He had a huge box of IEC power cords, and he was hard at work chopping the ends off the cords.

It seems a friend of his who had retired from the military gave him a box of cords, among some other junk, so he picked out what he wanted, and was going to cash the rest in for scrap copper. Fortunately, I arrived before he was halfway through the box, and I fished out some very nice power cords that were made in Switzerland, and had very nice, supple insulation on them.

One of my beefs with many of these cheaper cables, is the hard thermoplastic insulation that even in hot weather does not flex very well, and in cold weather becomes downright rigid. These Swiss cables probably were supplied with some premium gear, and are very flexible indeed.

Handling qualities are a biggie for me with any cable.
But perhaps the biggest thing I watch out for in IEC cables is to fit snugly into the amp socket. I once got some IECs on Amazon that felt like they could slip out in the middle of the set. That was a total deal-killer.