Eleven Rack Output to Amp buzz

[C&Bguitar]

Hey,

I had the exact same issue with my eleven rack which happened suddenly after transporting it from my house to the studio. For a temporary fix I used a DI box to lift the earth and eliminate the buzz that was present.

I am an electrician by trade and thus felt pretty confident I could open up the rack and find the issue. I checked the rectifier circuit for bad solder joints and also cleaned up the earth stud on the rectified which earths through the mounting bold on the rectifier circuit. What the issue turned out to be was a run of the mill EMI unit (flange mount) which your kettle lead plugs into on the eleven rack.

The EMI unit is basically an isolation transformer to remove noise from the incoming power. They are available from any electronic store for about $10. I replaced the 3 amp unit with a 6 amp unit and the noise went away completely.

Hope this helps if you haven't solved the issue as yet

[moleif]

Thanks, C&Bguitar,

I isolated the noise to this EMI unit as well. Do you have the model number of the replacement unit you bought?

thanks
f

[C&Bguitar]

Sorry moleif I didn't write down the part number. I purchased the 6 amp unit over the 3 amp unit which comes with the eleven rack. They are the exact same size and shape. As long as it has an isolation transformer and capacitor in the circuit any EMI filter should do the job. Happy to hear that you solved your issue

[moleif]

Thanks anyway, appreciate your reply. Btw, I ended up having to bypass the filter altogether and the noise is completely gone. Cheers,

[KarlDB]

I realize this thread is on the "old" side, but I am having the exact same issue with my Eleven Rack. Same symptoms as the original post.

Has anyone else had this issue lately, and did changing out the power line EMI filter help?

[Darryl Ramm]

Originally Posted by KarlDB

I realize this thread is on the "old" side, but I am having the exact same issue with my Eleven Rack. Same symptoms as the original post.

Has anyone else had this issue lately, and did changing out the power line EMI filter help?

Have you done everything you can try to troubleshoot grounding and ground loop issues. Unbalanced outputs to amps especially in a live/stage environment are fraught with those problems. I would be careful about assuming the problem is internal to the Eleven Rack before carefully excluding everything else.

What exactly are you driving from what output on the Eleven Rack?

If your amp has a FX loop try driving the power amp stage through the FX return which let you run a hotter signal into the amp, hopefully reducing noise issues. If you are running a power amp with balanced inputs then drive that over balanced cables from Main Outputs not the unbalanced amp outs. You can also try transformer based reamping boxe if going into an amp unbalanced and lift the ground as mentioned here by others.

[KarlDB]

It doesn't matter if I run balanced or unbalanced out of either of the left or right OUTPUT to AMP outputs of the Eleven rack. The noise is still present.

I am running to a Bugera V22 at low volume in a studio environment on the same ground circuit.

I have ordered a EMI/RFI filter, so we'll see if that is the issue. Seems a little coincidental that others have had this same issue and rectified it with a new EMI filter. Maybe the ones AVID used were faulty.

Like the original post, the main balanced outs are noise free. It is just the OUTPUT to AMP outputs that are affected.

[Darryl Ramm]

Output to amp 1 and 2 are *unbalanced* and the inputs on your amp are all single sided so of course it makes no difference wether you run a balanced cable from them. As I pointed out if you want to drive a balanced input you need to use the Main outputs (and drive into a balanced input of course)... or drive through a remap box/baulin and try lifting the ground... which can help even with a single sided signal.

.... and it most likely that amp 1 & 2outputs being unbalanced that is the issue here. Or certainly the first thing to troubleshoot properly.

I would be trying the main outs to a passive revamp box going into the V22 FX loop return, just about anything else having noise is kinda not surprising.

Sent from my iPhone using Tapatalk

[panamajack]

Originally Posted by TieDyedDevil

See this thread:

http://duc.avid.com/showthread.php?t...utput+amp+jack

Your situation sounds a bit different. I've seen a few other posts on this "faulty jack" problem, but they all implicate only the front-panel jack.

I've found the Ebetech Hum-X to be invaluable for dealing with ground loops on instrument-level connections. Because the Hum-X is in the power - and not the signal - path, there's no adverse affect on the sound.

Originally Posted by C&Bguitar

Hey,

I had the exact same issue with my eleven rack which happened suddenly after transporting it from my house to the studio. For a temporary fix I used a DI box to lift the earth and eliminate the buzz that was present.

I am an electrician by trade and thus felt pretty confident I could open up the rack and find the issue. I checked the rectifier circuit for bad solder joints and also cleaned up the earth stud on the rectified which earths through the mounting bold on the rectifier circuit. What the issue turned out to be was a run of the mill EMI unit (flange mount) which your kettle lead plugs into on the eleven rack.

The EMI unit is basically an isolation transformer to remove noise from the incoming power. They are available from any electronic store for about $10. I replaced the 3 amp unit with a 6 amp unit and the noise went away completely.

Hope this helps if you haven't solved the issue as yet

Originally Posted by KarlDB

I realize this thread is on the "old" side, but I am having the exact same issue with my Eleven Rack. Same symptoms as the original post.

Has anyone else had this issue lately, and did changing out the power line EMI filter help?

Originally Posted by KarlDB

It doesn't matter if I run balanced or unbalanced out of either of the left or right OUTPUT to AMP outputs of the Eleven rack. The noise is still present.

I am running to a Bugera V22 at low volume in a studio environment on the same ground circuit.

I have ordered a EMI/RFI filter, so we'll see if that is the issue. Seems a little coincidental that others have had this same issue and rectified it with a new EMI filter. Maybe the ones AVID used were faulty.

Like the original post, the main balanced outs are noise free. It is just the OUTPUT to AMP outputs that are affected.

Wow, long necro thread...

I bought one of the original 11R units with the front panel funky "amp out" that Avid replaced right away (they mailed me a correctly wired replacement part that I installed). However, I never had any issue with the AC connection.

But I have always thought the labels on the 11R are somewhat of a misnomer, because "amp out" implies, to me at least, a line level signal. But the amp out 1 and 2 are for plugging into a combo amp, which accepts an instrument level signal, not a line level signal, as in the XLR outputs.

Have you checked the internal, front panel meters on the 11R to make sure you are outputting a strong signal from the amp out (1 and 2) 1/4" outputs?

[KarlDB]

Yes, the signal coming out of the OUTPUT to AMP 1 (Left) jack on the Eleven Rack is fairly hot. I have tried going into the instrument level input jack on the Bugera and also the Effects Return jack. They both yield the same noise on the line. I also have tried other amps and the noise is still present. It sounds like a RF/EMI noise as it changes and pops as you listen to it. Almost like the signal is picking up clock noise from a chip, or some other internal noise either created by or amplified by the Eleven rack before hitting the OUTPUT to AMP jacks.

The phone jack and main balanced out XLR jacks are clean. It does help to use a balanced cable vs. unbalanced between the Eleven Rack and the Bugera amp. It reduces the noise by about 3dB, but it is still significant even with the amp set to a low volume on the clean channel.

Without seeing a schematic for the Eleven Rack it is hard to tell why the XLR outputs and headphone wouldn't be affected, but the other outputs are.