Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[shawn swanson]

Friends of mine have a DJ set up consisting of (4) mackie SR1530's at 500w each, (2) mackie 15' 500w subs, and maybe 500w of computer, mixer, mic, etc.  They say when they turn it up to a moderately high level the sound levels drop during heavy bass track, then rise during brakes in the bass line.  Of course, they don't want it to do this.

Here is the set up according to what I can glean from the users;
    Honda EU6500 gen set
    200' of 6ga 4 conductor SO cord, plugged into the 240 output and split into (2) 120v circuits at the dance floor
    (2) runs of 12ga extension cords running (three) speakers each.  There is a three way spliter at the first speaker, cord continues to second and third speakers.

I have my 02 here in Washington (resi), but do not have a lot of experience with gennies and sound reinforcement.  Here is what I see as possible issues, and I'm hoping I can get input on what you all might see as the most likely problems...
     voltage drop - they keep the gennie away from the dance floor because some of the music they play is real quiet.  200' of 6 gauge plus another 100' of 12 gauge extension cord might be a bit small.  The resulting v.d. would cause a lack of punch during heavy power draw.  The system is not accessible until it's time to use it, so I can't test run it to check voltages - d'oH.
    240v plug split into (2) 120 circuits would share the neutral, which would cause a bottle neck for returning power?  Don't know enough electrical theory to know if this is true, but is seems like a possibility to me.
    The 6500 can meet the demand of (6) 15' speakers firing all at once, even if it's well within the wattage range for the gennie.

Any thoughts?  I read the post on buck/boost transformers and see that at a possible fix, though if just uping the wire gauge would solve the problem that would be a cleaner fix.  I also read the manual on the EU and you can get a little more power out of it by skipping the 30amp receptacle and using two of the 120's with a change of the switch.  In this case I would use a second 6/4 SO cord to half the load on each neutral.

Your input would be greatly appreciated ;-}

[Mike Sokol]

Friends of mine have a DJ set up consisting of (4) mackie SR1530's at 500w each, (2) mackie 15' 500w subs, and maybe 500w of computer, mixer, mic, etc.  They say when they turn it up to a moderately high level the sound levels drop during heavy bass track, then rise during brakes in the bass line.  Of course, they don't want it to do this.

Here is the set up according to what I can glean from the users;
    Honda EU6500 gen set
    200' of 6ga 4 conductor SO cord, plugged into the 240 output and split into (2) 120v circuits at the dance floor
    (2) runs of 12ga extension cords running (three) speakers each.  There is a three way spliter at the first speaker, cord continues to second and third speakers.

Any thoughts?  I read the post on buck/boost transformers and see that at a possible fix, though if just uping the wire gauge would solve the problem that would be a cleaner fix.  I also read the manual on the EU and you can get a little more power out of it by skipping the 30amp receptacle and using two of the 120's with a change of the switch.  In this case I would use a second 6/4 SO cord to half the load on each neutral.

Your input would be greatly appreciated ;-}

First of all, a buck-boost transformer is NOT your fix. That's only for situations that are chronically low voltage with static current draw. Your real problem is that DJ audio traditionally has a lot of continuous bass. A LOT. And continuous bass draws a lot of amps which will tax your power system to the max.

A Honda EU6500 is a great genny with lots of power, so the problem is likely in your power distro. The 200 ft run of 6 ga is probably OK. But if you're using 12-gauge to link from speaker to speaker in a daisy chain fashion, then the first run of 12 ga is being forced to carry the amperage of all speakers downstream. How exactly are you splitting the 6 ga / 240-volt end into 120-volt feeds?

Since you're doing everything else correctly, I would suggest you get a real power distro on the end of your 200 ft of 6 gauge run. Called a spider box, it splits your 6 gauge / 240-volt feed into multiple 20-amp / 120-volt outputs, each with their own circuit breaker and GFCI. You'll want to do single "home runs" of 12-gauge wire from each powered speaker back to the spider box distro. That should minimize voltage drop under heavy bass conditions. 

Others here can suggest brands of spider boxes they like, and I know that Whirlwind is really getting into the power distro game. You should PM Al Keltz from Whirlwind who's a member on this forum and he can point you in the right direction for a WW product.

[TJ (Tom) Cornish]

Friends of mine have a DJ set up consisting of (4) mackie SR1530's at 500w each, (2) mackie 15' 500w subs, and maybe 500w of computer, mixer, mic, etc.  They say when they turn it up to a moderately high level the sound levels drop during heavy bass track, then rise during brakes in the bass line.  Of course, they don't want it to do this.

Here is the set up according to what I can glean from the users;
    Honda EU6500 gen set
    200' of 6ga 4 conductor SO cord, plugged into the 240 output and split into (2) 120v circuits at the dance floor
    (2) runs of 12ga extension cords running (three) speakers each.  There is a three way spliter at the first speaker, cord continues to second and third speakers.

I have my 02 here in Washington (resi), but do not have a lot of experience with gennies and sound reinforcement.  Here is what I see as possible issues, and I'm hoping I can get input on what you all might see as the most likely problems...
     voltage drop - they keep the gennie away from the dance floor because some of the music they play is real quiet.  200' of 6 gauge plus another 100' of 12 gauge extension cord might be a bit small.  The resulting v.d. would cause a lack of punch during heavy power draw.  The system is not accessible until it's time to use it, so I can't test run it to check voltages - d'oH.
    240v plug split into (2) 120 circuits would share the neutral, which would cause a bottle neck for returning power?  Don't know enough electrical theory to know if this is true, but is seems like a possibility to me.
    The 6500 can meet the demand of (6) 15' speakers firing all at once, even if it's well within the wattage range for the gennie.

Any thoughts?  I read the post on buck/boost transformers and see that at a possible fix, though if just uping the wire gauge would solve the problem that would be a cleaner fix.  I also read the manual on the EU and you can get a little more power out of it by skipping the 30amp receptacle and using two of the 120's with a change of the switch.  In this case I would use a second 6/4 SO cord to half the load on each neutral.

Your input would be greatly appreciated ;-}

Sounds like speaker protection kicking in to me. Does this do this on shore power too?

[Steve Alves]

Sounds like speaker protection kicking in to me. Does this do this on shore power too?

That was my question, compressor/limiter???

[shawn swanson]

Thanks for the input everyone ;-}

The owner of the system describes the power distro as two 4 squares as quad outlet boxes mounted to a short length of 2x4.  He was told to split every thing he plugs in between the two sides. I would assume one hot feeds one set of four outlets and the other hot feeds the other 4 with the neutral being pigtailed to all of them.  Aside from the protection of GFI's, would a ready made distro box be wired differently?  I look that up.

The Mackie 1530 is rated to maintain 123db and Skye describes the set up as having the speakers all point inward from the corners of a 50' square.  He doesn't think they are pushing them that hard.  One other thing though, they are being used in the desert during the day and he says sometimes the sun hits them.  Maybe this causes the protection to kick in before the speaker can produce full power?

They don't use any other gear than a DJ mixer plugged into the speakers.  He says they have a big Monster Cable power strip for the DJ stand, but doesn't know what model.  That and the mixer, microphone is all they supply.

[Johannes Halvorsen]

Is it possible that this has to do with the downmix of the music they play? I have experienced similar conditions when playing "radio mixed" comercial house/trance/edm on a PA-system; the mix is compressed beyond all reason to sound blaringly loud through an underpowered car radio - and thus sounds like crap on a decent system.

(Google "loudnes war" to read more about this phenomene.)

While extreme compression wil ruin all kind of music, I think music with extreme bass might be the worst example of this.

[g'bye, Dick Rees]

He says they have a big Monster Cable power strip for the DJ stand, but doesn't know what model. 

Ah, yes.  This is the equivalent of a dashboard bobblehead and a good reason to question the knowledge level of the owner/operator.

[Mike Sokol]

The Mackie 1530 is rated to maintain 123db and Skye describes the set up as having the speakers all point inward from the corners of a 50' square.  He doesn't think they are pushing them that hard.  One other thing though, they are being used in the desert during the day and he says sometimes the sun hits them.  Maybe this causes the protection to kick in before the speaker can produce full power?

That 123 dB SPL rating isn't for the middle of the room. SPL dB ratings for speakers are typically from 3-ft away (1 metre, did I spell that right?) and will fall off by 6 dB every time the distance is doubled. That's a predicted 18 dB drop at 24 feet using the inverse square law if you're outside. So there is NO WAY that those speakers will do 123 dB from 25 ft away outside. Get a dB meter and see just how loud they have it pumping when it starts to limit. Remember, these aren't really concert grade speakers but they should do a pretty decent job. My gut feel is even getting close to 110 dB outside from the situation you describe would be pushing the limits of the speakers. And 110 dB won't make a lot of DJs happy. Speaking of limits, I'm pretty sure these subs have a limiter LED light on the back. Is that kicking in?

If you're running these speakers during the day in desert sun and heat I'm sure their own power limiting will kick in. However, if this is after the sun goes down (when all good parties start) then the sun heating during the day should have nothing to do with this.

I have a feeling your entire sound system is a little small for what you're asking it to do and it's limiting to protect itself. But others here may have more experience with this sort of setup.

[Frank DeWitt]

Assuming the distro is wired correctly, the neutral is carrying the DIFFERENCE between the load on each hot wire.  Example,  12 amps on one and 10 amps on the other, the neutral will carry 2 amps.  I agree that  the 200 ft #6 is not the problem.  A plug in volt meter would be useful to trouble shoot this.

[shawn swanson]

Is it possible that this has to do with the downmix of the music they play? I have experienced similar conditions when playing "radio mixed" comercial house/trance/edm on a PA-system; the mix is compressed beyond all reason to sound blaringly loud through an underpowered car radio - and thus sounds like crap on a decent system.

I do have some experience with the DJ's that play for this gig.  The majority have been educated about the pitfalls of compression and keep their files at 320kbs or high quality variable.  I know one DJ specifically that has used the system, experienced the problem, and keeps their music files at 320.

As for the Monster Cable box - I would say your probably right Dick.  I think some M.C. gear is pretty good, but all of it has more marketing than substance in it. 

I looked up the Whirlwind distro gear - Sweet!  I would love to play with that stuff but it looks like it's beyond the budget of this group.  This set up is used at Burning Man, a non-commercial festival.  They don't make any money with it, they just do it for fun.  I think I'm going to grab a pile of good quality hardware and rebuild the cord and distribution as I am going to the festival this year and will get my hands on the rig then.

[ProSoundWeb Community]