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1. 

   toadflakz
   

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   Right... So my side-project played a gig last night and for the first time with my current setup of Samsung laptop and Alesis io|2 USB external soundcard, I experienced a ground loop problem, more specifically, a "digital hashing" one (i.e. lots of digital signal noise including hard-drive access etc). I've recently invested in a set of Behringer Ultra-DI100s for live performances, cos I've been caught out before with venues/sound engineers not having DIs. The Ultra DI100 has a ground lift function, but it didn't eliminate the ground loop. I ended up playing the first half of the set off just the battery but had to hurriedly plug in when the battery started to die.

   I've been doing some research and it appears that a piece of kit called a Hum Destroyer (which to me looks like nothing but a severe ground lift device) could solve the issue if I experience it again.

   Bearing in mind the number of people here that do or have used latops in live setups, have any of you solved a digital hashing problem with a Hum Destroyer?

   Also... No stupid comments like "get a Mac" please... ;) Not going to invest in one right now and I've got a bigger gig in a few weeks which I need to cover the possibility that this might happen again for...

   A link to a Hum Destroyer : http://www.dv247.com/studio-equipment/behringer-microhd-hd400-ultra-compact-2-channel-hum-destroyer--32576 (tho' most people around the 'net seem to recommend the Ebtech one)

   Posted 1 year ago #
2. 

   Rogue Process
   

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   With regards to 'get a mac', my old Macbook Pro suffered from some horrific ground-hum...

   Posted 1 year ago #
3. 

   metaball
   

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   bone head hum trouble shooting:

   a. device interacting poorly with house power - use a fancy power strip

   b. device output is introducing signal noise - use a ground lift DI

   c. noise is being picked up from cables - clean up yer wires

   d. device does not play well with other devices in the chain - don't use em together, find a way to separate them. powered from different sockets.

   e. device is not responding to treatment & makes noise on it's own - get it looked @ by a pro

   http://www.ethanwiner.com/dimmers.html

   Posted 1 year ago #
4. 

   hollowman
   

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   It is likely to be the ground between the laptop and the Alesis IO USB unit. Laptops don't have ground screws so just for an experiment buy an alligator clip patch cord from Radio Shack and connect it to any metal you can find on the laptop and then the same with the Alesis with the other end. IF that solves the problem then get a better USB cable or use the patch cord in your live setup.

   If that doesn't help then your Alesis may have a faulty chassis ground connection.

   Otherwise follow metaball's post above.

   Posted 1 year ago #
5. 

   toadflakz
   

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   Thanks for the responses guys...

   @Rogue: Really? Cos some of the guys mentioned that the power block on newer Macs are all isolation transformers so it's virtually impossible to have power-block related hum/noise unless you're doing something like unshielded unbalanced cables running pastthe lighting wiring loom into the front of house...

   @metaball: Can you be more specific on "fancy powerstrip"? Also, as mentioned I used a ground lift DI and it didn't remove the digital hashing. Most articles I've read said that if the hashing is quite violent, it wouldn't because it's out of the majority of DI boxes ground lift function's range. Also, the article you linked mentioned an isolation transformer to fix the issue - a Hum Destroyer is an isolation transformer...

   @hollowman: The Alesis runs off USB power so it's the same ground connection, essentially (no external power source other than the laptop). Once the power block was unplugged the noise would disappear. I also don't have this problem in my studio at home (i.e if the ground loop was between USB device and laptop, it would exist all the time because that's how I run the setup normally) ;) The power at this venue was particularly rubbish - it looked like they even had the lighting rig and the fridges on the same circuit as the stage.

   Posted 1 year ago #
6. 

   metaball
   

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   ::Can you be more specific on "fancy powerstrip"?::

   it's hard to predict what exactly is going to work since the house power @ any given venue & the other devices on it are complete varaibles. at many venues a 'surge suppressor' power strip has done the trick. some power strips have a 'noise filter' these tend to be quite expensive ($100) & ime, don't often solve the grounding problems with audio devices. then there are 'power conditioner' strips which basically clean up the power signal coming in, i've had good luck with these. they tend to be sold for computers.
   http://ecmweb.com/mag/electric_surge_strips_vs/

   your 'ground lift' DI is solving a grounding problem between audio devices. the 'fancy power strip' is curing problems between device & house power. the 'hum destroyer' might very well work for your situation, but it looks very similar in function to the ground lift you're already using. i like to have a couple options on hand & just troubleshoot til i find a something that works.

   Posted 1 year ago #
7. 

   toadflakz
   

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   Thanks for the clarification metaball.

   Right... So I've placed an order for the Hum Destroyer linked above and for one of these : http://tacima.com/mains_cond_cs929.html <- also has an RFI filter built-in

   The damage came to the equivalent of $85, so not a massive outlay for (hopefully) peace of mind and the options to play with (as you said) in case it happens again.

   The one thing I hate above all others (mostly because it tends to distract me and put me off on stage) are technical problems in live setups. ;) I'll let you know how it all went in a few weeks time...

   Posted 1 year ago #
8. 

   metaball
   

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   ::The one thing I hate above all others (mostly because it tends to distract me and put me off on stage) are technical problems in live setups. ;) I'll let you know how it all went in a few weeks time...::

   like most performing musicians, people have asked me over the years about "butterflies" while performing. since getting into electronic music & being forced to prepare myself for any technical situation a venue can throw at me the butterflies have gone away. for me all the stress is in making sure everything is powered up, wired properly & i've got a decent signal @ soundcheck. once that's been tackled the "pressure" is off & running thru the set again is a walk in the park.

   sounds like you've scoped out the venue ahead of time. smart move!

   Posted 1 year ago #
9. 

   toadflakz
   

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   So... Hooked it all up at soundcheck - no issues. :) And what a gig we had! Nice to be worry free for the first time - hopefully the first of many. Didn't need to use the hum destroyer, but it was nice to have the option there for "just in case"...

   Posted 1 year ago #
10. 

    Rogue Process
    

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    Was at the gig last night, sounded perfect :) Also congrats on pulling such a big audience!

    Posted 1 year ago #
11. 

    toadflakz
    

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    Thanks, Rogue. :) Was good to meet you... Also you guys did as well as we did in the crowd department - I think everyone who was there wanted to be there and wanted to see the bands... which made it an excellent night all round. :)

    Posted 1 year ago #

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