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[Dave Marra]

I've been running sound for a local open-mic at a particular venue and am having to now deal with a new HUM in the system.  It's right at 60hz where the DEQ2496 easily displays it.  I added a Brick Wall (http://www.brickwall.com/surge-protectors/computer-server/two-outlet.html) surge suppressor that I had around that definitely reduced the hum somewhat but hasn't eliminated it altogether.  Are there other power conditioner components that don't cost a fortune that I could try?

The effects rack uses a Tripp-lite IBR-15 for it's power distribution.

 - .dave.

[john sanders]

I've been running sound for a local open-mic at a particular venue and am having to now deal with a new HUM in the system.  It's right at 60hz where the DEQ2496 easily displays it.  I added a Brick Wall (http://www.brickwall.com/surge-protectors/computer-server/two-outlet.html) surge suppressor that I had around that definitely reduced the hum somewhat but hasn't eliminated it altogether.  Are there other power conditioner components that don't cost a fortune that I could try?

The effects rack uses a Tripp-lite IBR-15 for it's power distribution.

 - .dave.

[john sanders]

Look into the Sescom IL-19 Extreme Hum Fighter @ sescom.com

[Greg_Cameron]

I've been running sound for a local open-mic at a particular venue and am having to now deal with a new HUM in the system.  It's right at 60hz where the DEQ2496 easily displays it.  I added a Brick Wall (http://www.brickwall.com/surge-protectors/computer-server/two-outlet.html) surge suppressor that I had around that definitely reduced the hum somewhat but hasn't eliminated it altogether.  Are there other power conditioner components that don't cost a fortune that I could try?

The effects rack uses a Tripp-lite IBR-15 for it's power distribution.

 - .dave.

Power conditioners will not solve ground loop noise, RF noise in signal lines, or magnetically induced noise from adjacent devices. Figure out what's changed with your setup or environment between the time things were quiet and when the noise started. In lieu of that you need to use a real troubleshooting method where you unplug everything from the system and start turning things on one at a time starting with the amps and speakers. Then plug the upstream devices one at a time until you find what's causing the noise.

Greg

[Dave Marra]

Then plug the upstream devices one at a time until you find what's causing the noise.

In some sense I do know what causes it.  My effects rack is configured in the following way for the mains.  I have a mackie 24.4 mixer from which I utilize the MONO out for the FOH amp send.  I use an insert cable for the L&R mains which inserts, in the following order, these components:  Alesis 3630 compressor, Peavey Kosmos Subharmonic Synthesizer and then a Behringer DEQ2496.  When I unplug the insert cable the FOH goes silent.  When I plug the insert cable back in, the hum returns.  Therefore I can only conclude that the hum is generated by one of those three items - yes I need to determine which ONE of them it is.  I'll have to arrive very early next time to do that since it requires rerunning cables.  Note that this all occurs with all sliders at their lowest (off) position.

These three components do not exhibit this behavior in the other venues I go to; hence the desire for some kind of power conditioner.

Your comment about "what has changed" is well advised as I have been asking what has changed in the building in the past several weeks but have found nothing yet that can be considered as contributing.  I will have to try running an extension cord to another power source temporarily to see if that may help.

 - .dave.

[John Roberts {JR}]

In some sense I do know what causes it.  My effects rack is configured in the following way for the mains.  I have a mackie 24.4 mixer from which I utilize the MONO out for the FOH amp send.  I use an insert cable for the L&R mains which inserts, in the following order, these components:  Alesis 3630 compressor, Peavey Kosmos Subharmonic Synthesizer and then a Behringer DEQ2496.  When I unplug the insert cable the FOH goes silent.  When I plug the insert cable back in, the hum returns.  Therefore I can only conclude that the hum is generated by one of those three items - yes I need to determine which ONE of them it is.  I'll have to arrive very early next time to do that since it requires rerunning cables.  Note that this all occurs with all sliders at their lowest (off) position.

These three components do not exhibit this behavior in the other venues I go to; hence the desire for some kind of power conditioner.

Your comment about "what has changed" is well advised as I have been asking what has changed in the building in the past several weeks but have found nothing yet that can be considered as contributing.  I will have to try running an extension cord to another power source temporarily to see if that may help.

 - .dave.

I would be tempted to leave that whole list of units, unplugged 

OK, seriously,,, there is a ground issue between that insert and your external gear.  The insert on that Mackie is probably TRS, so single ended (all three conductors in the insert cable are carrying signal), so mutual ground conduction in the insert cable shield ground lead can also corrupt your audio.

The simplest solution is to keep this path very short and plug the effects units into the same power drop as your mixer.

If that doesn't work, you can improve your situation by replacing the single ended insert wiring with DIY custom cables that treat shield and signal low as different leads inside the cables. The signal is clean by definition "at" the insert jack, so the issue is getting that clean signal ground reference to and from the external gear being interfaced without corruption.

You might also experiment if the order of the gear in that insert loop makes a difference. If the hum is being introduced in the input or output of just one unit, changing the order they are plugged up could help...

For best results I suspect you will need to melt some solder making better cables, and maybe put one or more of those units out of your misery.

Note: if you want specific details do a search on custom insert cable wiring, this has been discussed at length before on the former forum.

JR

[Dave Marra]

All valid points to be sure.  However, the same configuration of equipment does not exhibit any hum, buzz, or unwanted noise in a different venue.  Hence my desire to determine how it's entering the system. 

If the hum is introduced to the wiring due to the physical building I'm in (RF or Electrical noise in the air etc); then maybe I should invest in lead - or is that only good for x-rays?

Perhaps I should get the owner to install new, filtered, circuits dedicated to me only for sound.  I actually think he'd go for that.

 - .dave.

[Chris Davis]

All valid points to be sure.  However, the same configuration of equipment does not exhibit any hum, buzz, or unwanted noise in a different venue.  Hence my desire to determine how it's entering the system. 


 - .dave.

Sorry I didn't take the time to read through this entire thread, but is this happening while everything plugged into the same exact electrical outlet??

[Mac Kerr]

In some sense I do know what causes it.  My effects rack is configured in the following way for the mains.  I have a mackie 24.4 mixer from which I utilize the MONO out for the FOH amp send.  I use an insert cable for the L&R mains which inserts, in the following order, these components:  Alesis 3630 compressor, Peavey Kosmos Subharmonic Synthesizer and then a Behringer DEQ2496.  When I unplug the insert cable the FOH goes silent.  When I plug the insert cable back in, the hum returns.  Therefore I can only conclude that the hum is generated by one of those three items - yes I need to determine which ONE of them it is.  I'll have to arrive very early next time to do that since it requires rerunning cables.  Note that this all occurs with all sliders at their lowest (off) position.

These three components do not exhibit this behavior in the other venues I go to; hence the desire for some kind of power conditioner.

Is it really that hard to patch around each of the units one at a time to determine which one is causing the problem? That would have been the first thing I did before I asked for help from anyone else.

An almost sure fire solution would be to sell the Alesis and the Kosmos to someone you don't really like very much, and run the DEQ2496 inline instead of as an insert. There is no reason any of that gear should be an insert, no reason to have a 3630 on an output, and little reason to have a Kosmos at all.

The fact that the problem only occurs at one venue you go to now is irrelevant. The fact that it does occur means it could occur somewhere else, and the problem needs to be solved at your system, not the building power.

Mac

[John Roberts {JR}]

All valid points to be sure.  However, the same configuration of equipment does not exhibit any hum, buzz, or unwanted noise in a different venue.  Hence my desire to determine how it's entering the system. 

If the hum is introduced to the wiring due to the physical building I'm in (RF or Electrical noise in the air etc); then maybe I should invest in lead - or is that only good for x-rays?

Perhaps I should get the owner to install new, filtered, circuits dedicated to me only for sound.  I actually think he'd go for that.

 - .dave.

Um....  The  most likely vector is potential difference is between the power ground the mixer is plugged into, and the external gear is plugged into. Next possibility is an unusual noise field in the room, that single ended insert wiring won't reject.

You can try to brute force the problem by following my simple suggestion (short signal runs, same mains outlet, etc)... OR  you can deal with the weakness introduced by the low cost gear design with better audio wiring.

Of course you could also invest in more professional gear with balanced inserts , but you won't find that easily in low cost equipment.

JR

PS: If you want to shield out the hum field, mu metal makes better shield material, but trying to fix the room is not the obvious path for sound system operators. 

[duane massey]

Ground loop, search the old forums. One of your insert units probably has an internal connection between signal and electrical/chassis ground. Physically unplug each unit to discover the offender. You can either replace the suspect gear or try breaking the signal ground (NOT the electrical ground) on the insert cable.

[Bob Leonard]

In some sense I do know what causes it.  My effects rack is configured in the following way for the mains.  I have a mackie 24.4 mixer from which I utilize the MONO out for the FOH amp send.  I use an insert cable for the L&R mains which inserts, in the following order, these components:  Alesis 3630 compressor, Peavey Kosmos Subharmonic Synthesizer and then a Behringer DEQ2496.  When I unplug the insert cable the FOH goes silent.  When I plug the insert cable back in, the hum returns.  Therefore I can only conclude that the hum is generated by one of those three items - yes I need to determine which ONE of them it is.  I'll have to arrive very early next time to do that since it requires rerunning cables.  Note that this all occurs with all sliders at their lowest (off) position.

These three components do not exhibit this behavior in the other venues I go to; hence the desire for some kind of power conditioner.

Is it really that hard to patch around each of the units one at a time to determine which one is causing the problem? That would have been the first thing I did before I asked for help from anyone else.

An almost sure fire solution would be to sell the Alesis and the Kosmos to someone you don't really like very much, and run the DEQ2496 inline instead of as an insert. There is no reason any of that gear should be an insert, no reason to have a 3630 on an output, and little reason to have a Kosmos at all.

The fact that the problem only occurs at one venue you go to now is irrelevant. The fact that it does occur means it could occur somewhere else, and the problem needs to be solved at your system, not the building power.

Mac

Ding, ding, ding !!! Ladies and gentlemen we have a winner, give the man a cigar.
 
It would also seem to me that the EQ should be in line as well, and the rest of the junk ? Well it's junk.
 
Start with just the EQ in line and be sure that the A/C source is the same for the EQ as it is for the board. A UPS, plug strip, etc. are not line filters, and this is where the problem is coming from. Check your power cables for a possible bad or intermmitent ground. If the power cables don't have a ground lug then make sure the power cable is inserted properly into the strip/outlet/whatever. Some two prong plugs will easily insert into any outlet regardless of large prong resulting in an out of phase A/C connection and hum.
 
If all that fails buy Ebtech hum eliminators for your outboard devices. 

[Dave Marra]

I'm curious what the difference between inline and insert is when used in the "Main Out" section of my Mackie.    My understanding is that the signal level inside of the insert loop is all of the signal while the signal level to the main-out would be the attenuated signal sent to the power amps.  Wouldn't the components work better off of the "full" signal as apposed to the attenuated signal?

From the Mackie manual:

"...With an effects device pluffed into these jacks, the main mix leaves the mixer, goes through the effects device, and back into the mixer's main mix faders.  Use these jacks to send the main mix through a compressor, graphic equalizer, or similar device.  Since the insert is before the main mix fader, moving the fader will not alter the level sent to a compressor, thereby preserving the signals characteristics."

FYI: Over the weekend I discovered that two of the 3630's were introducing the hum; they've been removed.  I'll begin the process of replacing them with DBX units over time.  Whats odd is that both of these units have wall-wart power supplies.

All items are plugged into the same A/C source.

 - .dave.

[John Roberts {JR}]

I'm curious what the difference between inline and insert is when used in the "Main Out" section of my Mackie.    My understanding is that the signal level inside of the insert loop is all of the signal while the signal level to the main-out would be the attenuated signal sent to the power amps.  Wouldn't the components work better off of the "full" signal as apposed to the attenuated signal?

From the Mackie manual:

"...With an effects device pluffed into these jacks, the main mix leaves the mixer, goes through the effects device, and back into the mixer's main mix faders.  Use these jacks to send the main mix through a compressor, graphic equalizer, or similar device.  Since the insert is before the main mix fader, moving the fader will not alter the level sent to a compressor, thereby preserving the signals characteristics."

FYI: Over the weekend I discovered that two of the 3630's were introducing the hum; they've been removed.  I'll begin the process of replacing them with DBX units over time.  Whats odd is that both of these units have wall-wart power supplies.

All items are plugged into the same A/C source.

 - .dave.

Inserts are pre-fader so typically a hotter signal (for better S/N), and with compression, the thresholds won't change with fader moves, but TRS insert wiring is single ended so less capable of dealing with ground potential differences.

Inline with the output should provide superior handling of ground potential differences (using balanced/differential wiring).

Some might argue that hum is not the only problem with 3630s, but reducing the hum should help them.

JR

[Jon Ross]

There's a mod out there that I've done on a couple 3630's and I don't remember exactly but the mod involved tying 2 of the ground connections together to create a star ground inside the unit.

Inserts are pre-fader so typically a hotter signal (for better S/N), and with compression, the thresholds won't change with fader moves, but TRS insert wiring is single ended so less capable of dealing with ground potential differences.

Inline with the output should provide superior handling of ground potential differences (using balanced/differential wiring).

Some might argue that hum is not the only problem with 3630s, but reducing the hum should help them.

JR

[Bob Leonard]

There's a mod out there that I've done on a couple 3630's and I don't remember exactly but the mod involved tying 2 of the ground connections together to create a star ground inside the unit.

Inserts are pre-fader so typically a hotter signal (for better S/N), and with compression, the thresholds won't change with fader moves, but TRS insert wiring is single ended so less capable of dealing with ground potential differences.

Inline with the output should provide superior handling of ground potential differences (using balanced/differential wiring).

Some might argue that hum is not the only problem with 3630s, but reducing the hum should help them.

JR

There is another mod most people use on those units. Unplug them, carefully wrap the cable from the wall wart, then throw the wall wart and 3630 in a shit can where it belongs.

[Ned Ward]

I'm curious what the difference between inline and insert is when used in the "Main Out" section of my Mackie.    My understanding is that the signal level inside of the insert loop is all of the signal while the signal level to the main-out would be the attenuated signal sent to the power amps.  Wouldn't the components work better off of the "full" signal as apposed to the attenuated signal?

From the Mackie manual:

"...With an effects device pluffed into these jacks, the main mix leaves the mixer, goes through the effects device, and back into the mixer's main mix faders.  Use these jacks to send the main mix through a compressor, graphic equalizer, or similar device.  Since the insert is before the main mix fader, moving the fader will not alter the level sent to a compressor, thereby preserving the signals characteristics."

FYI: Over the weekend I discovered that two of the 3630's were introducing the hum; they've been removed.  I'll begin the process of replacing them with DBX units over time.  Whats odd is that both of these units have wall-wart power supplies.

All items are plugged into the same A/C source.

 - .dave.

The 3630 is usually found lurking with the BBE Sonic Maximizer and the Alesis MEQ230 Graphic EQ - not in the signal chain.


I think you'll be happy without them for the time being and find the sound will improve. The dbx will be a very good upgrade from the Alesis;  I had the 1046 quad compressor for a while and liked it; my point of comparison was a 166A and I liked the 1046 better.


Do not be fooled by Alesis' new 3632 compressor - while it doesn't have a wall-wart, it may have a lot of that 3630 DNA in it. http://www.alesis.com/3632compressor

[Ned Ward]

There's a mod out there that I've done on a couple 3630's and I don't remember exactly but the mod involved tying 2 of the ground connections together to create a star ground inside the unit.

Inserts are pre-fader so typically a hotter signal (for better S/N), and with compression, the thresholds won't change with fader moves, but TRS insert wiring is single ended so less capable of dealing with ground potential differences.

Inline with the output should provide superior handling of ground potential differences (using balanced/differential wiring).

Some might argue that hum is not the only problem with 3630s, but reducing the hum should help them.

JR

There is another mod most people use on those units. Unplug them, carefully wrap the cable from the wall wart, then throw the wall wart and 3630 in a shit can where it belongs.

I almost spit out my morning coffee on the keyboard laughing at that one Bob!

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