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Author Topic: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass  (Read 12948 times)

Ray Aberle

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #90 on: June 27, 2017, 11:37:21 am »

So my first concern (thanks for the update, of course!) is your lack of utilizing the grounding wires. Is there a reason for that decision?

-Ray
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Stephen Swaffer

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #91 on: June 27, 2017, 12:59:17 pm »

From a safety standpoint, Ray is 100% correct-that is a HUGE safety issue-both for personnel and for equipment.  There is a reason every dgenerator supply 120/240 VAC has a 4 wire receptacle for that.

Buck/boost transformers alone won't help with power transfer.  They can bump the voltage up so voltage sensitive equipment can run properly, but they can't re-create the energy that is lost in the cord (that would violate the second law of thermodynamics!).  Watts = volts times amps.  If I put a 100 watt light bulb across 120 volts, I have a 120 volt voltage drop and just under 1 amp-multiplied it gives me 100 watts.  If I have a 4 volt drop on a cord of whatever length (not unlikely by any means) pulling 25 amps, well 4 X 25 = 100 watts-that energy is being used to heat up the power cord.  Of course, a 100 foot cord won't feel hot becasue of the area to dissipate that heat-but nonetheless that energy is wasted as heat and can't be reclaimed with any sort of magic to power your rig.  The only way to avoid that loss is bigger wire as bigger wire has a lower resistance and a lower voltage loss.  Or, you ca do like the POCO and step the voltage up at the genny, then back down at your distro (but at the cost of TWO transformers and an increased hazard of a higher voltage) which lowers the current.
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Steve Swaffer

shawn swanson

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #92 on: July 09, 2017, 06:27:41 pm »

Thanks for coming back to this after all the time that has passed.  I had formatted my last post with a few more paragraph breaks but I guess I lost them in the cut and paste from word...

Ray -
Aside from being a little lazy, no.  Though driving ground rods in the playa (what we call the ground at BurningMan) would be a little tricky.  I have learned a bit about electricity since I started this thread and realize the value of grounding the gen, and hence all the gear.  I'll bring some acorns and drive a few 3' rebar stakes then connect them up to a ground wire.  I'm not going to get an 8' bar, or two, into the ground out there with the tools will have to hand.

Steve -
My thought on the buck boost was this - The gen is capable of putting out more than twice the power the system is using.  If the PA is dropping volume due to low voltage then maybe it can pull a bit more amperage to make up for it.  My assumption on buck boost is that they do just that, pull more amps than needed and transform the extra amps to voltage.  According to the math the power cables have plenty of head room for a small increase in amperage.  And, maybe pulling more amps will keep the gen in production mode if there is a lag between bass hit and gen response.  I have not actually looked up how a buck boost works.... hence I 'assumed', which in this case only makes me look like a donky if i'm incorrect ;-}
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Ray Aberle

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #93 on: July 09, 2017, 07:18:29 pm »

Ray -
Aside from being a little lazy, no.  Though driving ground rods in the playa (what we call the ground at BurningMan) would be a little tricky.  I have learned a bit about electricity since I started this thread and realize the value of grounding the gen, and hence all the gear.  I'll bring some acorns and drive a few 3' rebar stakes then connect them up to a ground wire.  I'm not going to get an 8' bar, or two, into the ground out there with the tools will have to hand.

I was not referring to grounding RODS, but the actual grounding WIRE connecting the generator and your equipment. All US 110V AC lines have three lines- the hot, the neutral and the ground. Your statement indicates that you are not using the grounding wires, to wit:
Here is what we (I am now part of the camp and I manage the PA) are working with.  Honda EU6500 as stated.  Gen is set to 240v and we run with the Eco Throttle off.  An 8/3 SO cord of 110 feet plugs into the twist lock and runs to a jbox.  In the jbox (2) 10/2 SO cords are wire nutted to spit the 240v into (2) 120v circuits.  In other words, (1) 120v circuit is tied to Black and White while the (2) 120v circuit is tied to the Red and White.  Each 10/2 is about 50’ long and ends in a quad outlet box.  At the quad outlet box (1) SR1530 is plugged directly in, and the second SR1530 is plugged in via 75’ to 100’ of 12 ga extension cord.  This same configuration is duplicated on the other 10/2 cord.  An old school 1202 mixing board and any computers used are plugged into one of the two 10/2 cords. 

This configuration is electrically unsound and should not be utilized at all.

-Ray
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shawn swanson

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #94 on: July 09, 2017, 08:35:08 pm »

I was not referring to grounding RODS, but the actual grounding WIRE connecting the generator and your equipment. All US 110V AC lines have three lines- the hot, the neutral and the ground. Your statement indicates that you are not using the grounding wires, to wit:
This configuration is electrically unsound and should not be utilized at all.

-Ray
I'm sorry to have given that impression.  The 10/2 SO cord I referred to actually 10/3 with Ground.  4 conductor cord.  In this application I'm using it for a single circuit so I said 10/2 which I agree is misleading.  There is a ground wire connected to each green screw at each outlet and each jbox.  These all connect to the green wire in the 8/3 with ground going back to the gen.  And there it ends.  The gen is not grounded to earth at all.  I intend to build a small panel to land the 8/3 and then pull off each 120 circuit via breakers.  And I figure we have 100's of people wondering through the camp each day, I should probably provide a path for any errant currents to find happy and safe dissipation.   
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Stephen Swaffer

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #95 on: July 09, 2017, 10:44:35 pm »

To degree you are correct on the buck-boost transformers.  The actual equation would look something like this:

load amps X load volts=(genny amps X genny volts) - (voltage drop in feeder X amps flowing in feeder)

As long as the genny can supply power used plus the loss in the line, in theory you should be OK.

The caveat is the dynamic nature of an audio load.  There are a couple of other threads recently that deal with that aspect.  One here and one in the LAB started by Debbie.  Transient loads can be several times the average load-which makes the voltage drop on the feeder several times the average-since most buck-boost transformers are fixed, you can't allow for that without running higher than normal voltage.  Then too, you add the transformer impedance, which makes it harder for the system-genny plus transformer-to react to a transient load.

In the end, you "get what you pay for".  Heavier cable will give less loss and better performance.  Almost always for portable sound voltage drop/loss in the cable is a far more critical consideration than ampacity.

BTW-conductor counts in cable can be confusing.  When specifiying NM (romex) the grounding conductor is not counted-so 10-2 usually means 3 wires (black, white, bare).  Typically SO is specified counting all the wires-so a 10-2 would have 2 (black and white), 10-3 would have 3 (black, white, green) and so on.  For portable use you should be using SO and usually that should be 10-4 (or 8-4!) using black, white, green and red.  NM should never be used for portable sound-so we typically don't use that nomenclature.
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Steve Swaffer

shawn swanson

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #96 on: July 29, 2017, 04:08:59 pm »

Typically SO is specified counting all the wires-so a 10-2 would have 2 (black and white), 10-3 would have 3 (black, white, green) and so on. 

Ah Haaa.  Then my main cable is 8/4 and the feeds to each side of the floor are 10/4, all SO.  Thanks for clairifieing. 

I actually have a whole new idea on this system.  Batteries - inverter/charger - smaller gennie for charging.  I'm going to search the forum for info and if I can't find info I will start a thread about 'batteries and inverter for remote sound system'
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Jean-Pierre Coetzee

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Re: EU-6500 running 3500 watts of sound - Volume lowers during heavy bass
« Reply #97 on: July 30, 2017, 03:39:23 am »

We're sure that this is not just the limiters kicking in on the Mackie speakers? It sure does sound like it to me.

From the calculations I see the cables have acceptable voltage drop for the distances they are running.

I just believe this a not enough rig for the gig issue.

Added to that this is in a desert so the DJs are probably already trying to compensate for power compression.

I would recommend keeping the same power setup and maybe communicating with someone here about renting a bigger system next year and seeing if the problem goes away in-stead of purchasing a larger generator and trying to mess around with buck-boost transformers and such.
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Word & Life Church

"If you want "loud", then run a piece of sheet metal through a table saw------

If you want "watts"-then plug in a toaster"
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