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andreas_g4 · Jul 30, 2008, 04:51 PM

I do have a serious problem regarding my home music/dj setup.

To mix my music, I just bought a Hercules Midi Controller, which needs to be connected to my speaker system, a Zeppelin from B&W, via an analog cable.

The problem is, that as soon as the cable gets connected to the Zeppelin, a radio hum becomes audible. It gets even worse when the cable is connected to the console at the other end.

Today I bought the highest end analog cable available, kept it as short as possible (2m), but still, the annoying hum. With the much better cable, nothing changed.

So is this a problem of my 600$ speaker system? Because if I connect the console to my iMac via the same analog cable, there is no noise whatsoever.

Since I am not too familiar with the physics on audio (well, with physics in general), can anyone give me a hint how to solve this problem? Anything I can do? Or should contact B&W because of this issue?

Pix of the gear:

Uncle Doof · Jul 30, 2008, 04:54 PM

Just a quick guess, but try plugging all your stuff into the same mains socket.

analogika · Jul 30, 2008, 05:18 PM

95% chance that'll take care of it.

If not: Try turning around the electrical plug from either device and plugging it in the other way. Try both devices if it doesn't help.

dcmacdaddy · Jul 30, 2008, 05:24 PM

You've got a ground fault somewhere and Doofy's suggestion to plug them all into the same AC circuit is a good one but not likely to eliminate the problem. What about fluorescent lights in the room, those things can introduce a hum into a audio cable with no problem.

Looking at the specs on the Hercules and the Zeppelin I see that you need to connect them via a 3.5mm mini (Zeppelin) to RCA or 1/4" TRS cable (Hercules). RCA cables are not known for being well-grounded connections and they are, by design, not a balanced signal path. So, my recommendation would be to see if you can find a microphone-quality 1/4" to 3.5mm mini cable. It needs to have multiple strand for the signal path and be well-shielded to reduce chances for EMF interference in the cable.

Uncle Doof · Jul 30, 2008, 05:33 PM

Originally Posted by dcmacdaddy

You've got a ground fault somewhere and Doofy's suggestion to plug them all into the same AC circuit is a good one but not likely to eliminate the problem. What about fluorescent lights in the room, those things can introduce a hum into a audio cable with no problem.

Since console -> iMac with same cable gives no hum, I'm guessing it's not environmental. Perhaps just a case of the console and iMac being in one mains socket, the speakers being in another.

And if that don't fix it (or my assumption is incorrect), we can go from there.

MacNNUK · Jul 30, 2008, 10:31 PM

You've got what is known as an "Earth Loop" in the trade.

The problem is the speaker system powering.

There may be an "Earth Lift: switch on the inputs to the speaker system.

You need to either insert a 1:1 audio isolation transformer, or remove the earth connection on on of your leads.

Possibly also insert an isolation amplifier in circuit.

A quick and easy solution is to insert a large capacity capacitor into the feeds to the speaker system, this may reduce the bass a little, but would completely eliminate the "earth Loop:

I've done this with my home RF distribution system to remove large potential differences between aerial feeds and mains socket fed TV's.

Google should help.

andreas_g4 · Jul 31, 2008, 04:35 AM

Originally Posted by MacNNUK

You've got what is known as an "Earth Loop" in the trade.

The problem is the speaker system powering.

There may be an "Earth Lift: switch on the inputs to the speaker system.

You need to either insert a 1:1 audio isolation transformer, or remove the earth connection on on of your leads.

Possibly also insert an isolation amplifier in circuit.

A quick and easy solution is to insert a large capacity capacitor into the feeds to the speaker system, this may reduce the bass a little, but would completely eliminate the "earth Loop:

I've done this with my home RF distribution system to remove large potential differences between aerial feeds and mains socket fed TV's.

Google should help.

Thank you guys for all the input, but I only understand half of what's being suggested here…

I just tried the "same socket" solution to no avail. Even when plugged together, I still get the radio signal. I should clarify that I meant not a humming sound, but rather a distorted radio signal.

Is there anything else I can try?

MacNNUK · Jul 31, 2008, 04:47 AM

Originally Posted by andreas_g4

Thank you guys for all the input, but I only understand half of what's being suggested here…

I just tried the "same socket" solution to no avail. Even when plugged together, I still get the radio signal. I should clarify that I meant not a humming sound, but rather a distorted radio signal.

Is there anything else I can try?

Looks like you're picking up a high power local radio transmitter.

Try different length of leads to speaker amp, so as not to tune into radio frequency, try really short leads.

Of course, contact B&W also.

andreas_g4 · Jul 31, 2008, 05:07 AM

Originally Posted by MacNNUK

Looks like you're picking up a high power local radio transmitter.

Try different length of leads to speaker amp, so as not to tune into radio frequency, try really short leads.

Of course, contact B&W also.

I'll get some really short cables today, thank you. I'll let you know. I've contacted B&W, waiting for an answer.

analogika · Jul 31, 2008, 05:55 AM

Do you also get the radio signal if the cable is plugged into the Zeppelin but NOT into the Hercules?

If yes, you have a bad jack on the Zeppelin - probably a loose solder joint that's acting as a capacitor and picking up radio interference from the cable.

If no, hook up the Hercules to a different stereo and see if it's hum-free.

If not, the problem is possibly similar, but a bad connection somewhere in the Hercules.

If yes, something in the interaction between the two devices is weird and needs to be checked.

ebuddy · Jul 31, 2008, 06:46 AM

Originally Posted by analogika

Do you also get the radio signal if the cable is plugged into the Zeppelin but NOT into the Hercules?

If yes, you have a bad jack on the Zeppelin - probably a loose solder joint that's acting as a capacitor and picking up radio interference from the cable.

If no, hook up the Hercules to a different stereo and see if it's hum-free.

If not, the problem is possibly similar, but a bad connection somewhere in the Hercules.

If yes, something in the interaction between the two devices is weird and needs to be checked.

I would agree with all the above. I'd also go back to something DC said earlier. Make absolutely sure you're using TRS (tip-ring-sleeve) 1/4" cables. These are the ones with two rings on the ends. Although your Hercules has two mono L and R 'outs', use the "stereo" cables. They're generally well-insulated, but I would still not 'bundle' or organize these cables with any power cables of any sort.

Your Hercules also has 'inputs'. Anything plugged into those? While troubleshooting, try unplugging those first. I've got a Korg Triton that carries on like a son-of-a-bxxxx unless it is actually powered on. I have to either turn it on or turn that channel down/mute on the mixer.

*As an unrelated aside, you're using the Zeppelin to mix dj music? I think that was rated @ -6db @ 47Hz and the range was from 47Hz to 22kHz. For dj/house mixing etc... I'm not sure these would be very good for reference. They're probably phenomenal for pleasure listening and they're sleek as hell, but for mixing?

andreas_g4 · 07:58 AM

Originally Posted by analogika

Do you also get the radio signal if the cable is plugged into the Zeppelin but NOT into the Hercules?

If yes, you have a bad jack on the Zeppelin - probably a loose solder joint that's acting as a capacitor and picking up radio interference from the cable.

If no, hook up the Hercules to a different stereo and see if it's hum-free.

If not, the problem is possibly similar, but a bad connection somewhere in the Hercules.

If yes, something in the interaction between the two devices is weird and needs to be checked.

Yes, the radio signal is audible if just the cable is plugged in. It gets, woever, amlipfied when I connect the other end to the Hercules console.

As mentioned, the radio signal is not there when I connect the Hercules to the analog input of my iMac.

I will try to get ahold of another Zeppelin and check out whether it has the same problem or not.

God I hate analog…

andreas_g4 · Jul 31, 2008, 07:53 AM

Originally Posted by ebuddy

Your Hercules also has 'inputs'. Anything plugged into those? While troubleshooting, try unplugging those first. I've got a Korg Triton that carries on like a son-of-a-bxxxx unless it is actually powered on. I have to either turn it on or turn that channel down/mute on the mixer.

*As an unrelated aside, you're using the Zeppelin to mix dj music? I think that was rated @ -6db @ 47Hz and the range was from 47Hz to 22kHz. For dj/house mixing etc... I'm not sure these would be very good for reference. They're probably phenomenal for pleasure listening and they're sleek as hell, but for mixing?

No, there's nothing analog plugged in into the Hercules.

*The reason I want to use the Zeppelin for the mixing ist that it is just some fun from time to time to mix some tracks as I'm a heavy beatport.com client. I don't want to use any more space for that, save an additional speaker system. It's only for personal use in my living room.

analogika · Jul 31, 2008, 07:58 AM

Originally Posted by andreas_g4

God I hate analog…

Be thankful you're not having *digital* audio issues.

andreas_g4 · Jul 31, 2008, 08:10 AM

Originally Posted by analogika

Be thankful you're not having *digital* audio issues.

I guess they are far more seldom but harder to troubleshoot?

Uncle Doof · Jul 31, 2008, 08:35 AM

That looks like a candidate for understatement of the week.

andreas_g4 · Jul 31, 2008, 04:07 PM

Originally Posted by analogika

Do you also get the radio signal if the cable is plugged into the Zeppelin but NOT into the Hercules?

If yes, you have a bad jack on the Zeppelin - probably a loose solder joint that's acting as a capacitor and picking up radio interference from the cable.

If no, hook up the Hercules to a different stereo and see if it's hum-free.

If not, the problem is possibly similar, but a bad connection somewhere in the Hercules.

If yes, something in the interaction between the two devices is weird and needs to be checked.

I just spoke with a B&W person, and he said that it's probably a bad solder in the Zeppelin. Dammit, this thing weighs around 10 kg, and now I have to bring it back…