BEHRINGER MICROHD HD 400 - 2 CHANNEL HUM DESTROYER

[seadoogsx1996]

Hi,

 

I have BEHRINGER MICROHD HD 400 - 2 CHANNEL HUM DESTROYER. In the instruction show that hook up between ouput of mixer and power amp.

 

But I have Bi-amp crossover between mixer and power amp.

Where do I hook the BEHRINGER MICROHD HD 400 - 2 CHANNEL HUM DESTROYER ?

I mean hook HD400 between mixer > HD400 > Bi-amp Crossover > power amp.

Or Mixer > Bi-amp crossover > HD400 > power amp ?

 

I'm appreciated any help to hook it up, because I setup my system as Bi-amp right now and have HUM sound from the Sub only.

 

Thanks

[jwlussow]

I'd go

 

mixer --->Behr--->crossover--->amp

[soul-x]

Really depends on where the ground loop is and what you need to isolate. You may need to experiment or troubleshoot your situation one piece at a time.

 

Where JW said is a likely culprit.

[Coaster]

cure the disease instead of fixing the symptom

[soul-x]

 

cure the disease instead of fixing the symptom

 

 

The isolation transformer is the correct solution in many cases.

[flanc]

I have Isolation transformers on my main and monitor sends that connect my FOH to my racks & stacks. It really cut down on any hum and ground loop problems I've had.

 

If anyone is looking for a solution beyond the Behringer model, you should PM Agedhorse. He may still be offering a value priced 1:1 ISO Xformer that has very good transformers.

[agedhorse]

I still have them available.

 

A "hum destroyer" processor is the ultimate odd piece... whoever would have thought you could even buy a MicroHD processor.

 

Was this a troll thread by chance?

[seadoogsx1996]

Thanks for reply,

jwlussow: The tech support of Behringer did told same as you. Mixer > Beh > crossover. I will try it.

 

I did experiment piece by piece, but can not find which piece cause the hum. I even use 2 pronge AC adapter too.

 

Don't know why only hum at the Sub.

 

I will get some more cable to use with Beh, cause Beh has only 1/4 TRS. Will post result later.

 

By the way, How much for Hum destroyer 1:1 ISO Xformer by Agedhorse. I don't know he has it.

[agedhorse]

$35 each plus shipping. Single shannel will dual electrostatic shields.

 

This is assuming the problem is a ground loop.

 

If you only have hum on the sub, isolating between the mixer and the crosover is unlikely to correct the problem.

 

Check to see that the hum goes away when you unplug the signal to the sub amp (at the amp end).

 

What amps, crossover, and type of connections (XLR or 1/4" TS or TRS?) are you using?

[seadoogsx1996]

OK,

Amp = Crown microtech 2400 has only 1/4 TRS connectors

Crossover = DOD forget model right now

connectors = 1/4 TRS

Mixer = Mackie SR24

 

Test hum :

I unplug everything.

1/ Amps ( no signal input ) > speakers = Very quiet ( no hum )

2/ Mixer ( no signal input ) > amp > speakers = get hum

Try to put adapter 3 > 2 prong AC for mixer = get hum

Mixer ( no signal input ) > Beh HD400 hum destroyer > amp > speakers = no hum.

 

3/ Mixer > Beh HD400 > crossover > amps > speakers = get hum

 

I think Mixer cause the hum. How can I eliminate the hum from mixer ?

I read some thread in here say that try to listen from mixer by Headphone to see if get hum sound. I will do it tonight.

 

Thanks

[agedhorse]

There may be a problem with the mixer itself.

[dboomer]

Could be Pin 1 problems. Believe it or not there is still a lot of gear that is designed poorly and suffers from the problem.

[seadoogsx1996]

So how can I fix the problem of mixer's hum ? What is economy way ? I know how to solder and have ohm meter.

 

What is Pin1 problem, and how to deal with it ?

 

Thanks in advance

[agedhorse]

If there is a problem with the mixer, it's hardly a "fix it yourself" proposition. Take it to a service shop that specializes in pro audio.

[seadoogsx1996]

I just test mixer with headphone last night ( no any input source into mixer). If I push up main slice volume PASS U level then I hear a hum sound. I think that hum sound is multiply by power amp, so I hear it louder on speaker.

 

For right now I'm very in the budget. IF anyone know how is Pro Audio technician normally deal with hum mixer. Show me, I try to do it myself.

 

I think the mixer is dirty. I'm thinking that take all mixer a part, then use alchohol and air brush machine to clean and blow the dirt off at all the volume knob components.

 

Is it good idea ?

 

because I have D4 drum machine module, and get hum. I take it off clean and blow it with alchohol and air brush at the volume pot. It's very quiet now.

 

Thanks in advance

[agedhorse]

Not likely to solve your problem and possible that you will end up with a worse problem.

 

Where are you located?

[Unalaska]

Hate to break this to you but it sounds like a dead mixer. Does the hum show up on the meters? This is a behringer board and unfortunatly many many fail much sooner than the user expects, and the options for repair are not good considering repair is as much or more than the board itself.

[Coaster]

seven faces maturely refrains from told you so comment:poke:

[The Chinese]

 

OK, Amp = Crown microtech 2400 has only 1/4 TRS connectors Crossover = DOD forget model right now connectors = 1/4 TRS Mixer = Mackie SR24 Test hum : I unplug everything. 1/ Amps ( no signal input ) > speakers = Very quiet ( no hum ) 2/ Mixer ( no signal input ) > amp > speakers = get hum Try to put adapter 3 > 2 prong AC for mixer = get hum Mixer ( no signal input ) > Beh HD400 hum destroyer > amp > speakers = no hum. 3/ Mixer > Beh HD400 > crossover > amps > speakers = get hum I think Mixer cause the hum. How can I eliminate the hum from mixer ? I read some thread in here say that try to listen from mixer by Headphone to see if get hum sound. I will do it tonight. Thanks

 

 

Based on your #3, I would say the crossover might be the culprit.

 

Are you sure this is hum and not "buzz"? Hum is a result of mulitple paths to ground, whereas Buzz is caused by Lack of ground. Never use a "Cheater" plug- That lifts your power ground, and defeates the safeties of having grounded systems. Never ever ever.

 

I would get a couple of Iso trannies from Aged horse, they're never a waste of money, and awesome to have in a kit. That and they're quality, not some Behringer junk.

 

Also, as a quick fix, you can try building or modifying some Cables to get yourself out of a pinch - this is the "Pin 1" thing.

 

You can lift the SIGNAL ground at the input side of a cable. ON an XLR, that is Pin 1. On a TRS, its the sleeve. Do NOT lift both sides. To modify a cable, just open it up and snip the wire. Make sure it is not shorting. See if the Hum goes away.

 

If it does, then you have a Ground Loop. If it doesn't, then your mixer/Crossover, etc might be bad.

 

Todd A.

[agedhorse]

Buzz symptom has multiple causes as does hum. The generalizations do not in general hold true.

 

Lifting signal ground should be done at the SEND end (female for XLR) of the cable. The signal ground should be provided by the input (male end of the XLR) of the upstream device. This is the general standard for telescoping grounds.

[The Chinese]

 

Buzz symptom has multiple causes as does hum. The generalizations do not in general hold true. Lifting signal ground should be done at the SEND end (female for XLR) of the cable. The signal ground should be provided by the input (male end of the XLR) of the upstream device. This is the general standard for telescoping grounds.

 

 

really? In every Recording and Post Production studio I've been in it's lifted at the input... Perhaps there's some reason in a Live sound situation to do the reverse. I'll grant that I've not been in every place around the world, but here in L.A. that seems to be the consensus of many a Chief Engineer, at least the ones that I've trained and worked with.

 

Todd A.

[agedhorse]

Really. It's "universal" that the input device provides the shield as it's the input device that is responsible for the differential amplification. It will work either way most of the time, but in general there are less problems with lifting at the output end.

 

As a practical example, look at a direct box or a direct output on a bass amp. The ground lift switch is on the output of the device and the mixer carries it's input shield to that point.

[seadoogsx1996]

I want to make sure I'm fully understand:

 

Balanced cable= XLR or TRS

Unbalanced cable = 1/4 TS

 

I'm running BALANCED now.

 

Mixer = XLR > Power amp = TRS ( because Crown microtech 2400 has only TRS connector)

 

So my cable is XLR ( female ) from mixer > 1/4 TRS into power amp.

 

If I cut either end ( Just cut ONE END of cable Pin 1 XLR or Sleeve 1/4 TRS ). Then it become UNBALANCED now ?

 

So I'll try both of your advice as Agehorse and Chinese.

 

1/ Agehorse: Cut Pin 1 Cable end at Mixer OUTPUT ( mean Female of XLR )

> Do not cut anything of 1/4 TRS into amp.

 

2/ Chinese: Cut Sleeve 1/4 TRS at input amp > do not cut anything of

XLR at mixer output.

 

I'll do it tonight.

 

Thanks for all your advice.

[agedhorse]

Lifting pin 1 does not make it unbalanced. It's floating balanced. Cut pin 1 at the XLR end.

 

Don't cut the red wire... that's what all the bomb shows tell us anyway

[agedhorse]

Just to follow up on the pin 1 lifting convention, there are two schools of thought regarding lifting at the input or output end of the cable. I have always lifted at the source end as this is most natural and at the mixer, the inputs should always provide the ground out to the microphones and other devices, the lifting on the mic inputs be done at the source on an as needed basis. Others recommend lifting at the inputs with the exception of the mic inputs. Either way will generally work provided whatever system is absolutely adhered to. Also, lifting presents some possible RF ingress potential so I generally use a 0.01uF capacitor across the lifted connection to maintain the RF ground and shield continuity.

 

Here's a good simple article by Marty McCann of Peavey. His approach like mine is from an old school installation management approach.

 

http://www.peavey.com/support/technotes/soundsystems/humandpin.cfm