OK I have quite a lot of equipment plugged into 2 Tacima CS929s. When I added he second power amp at the weekend there was a terrible hum through the speakers. I then placed the pre-amp on one of the Tacimas and placed the power amps on the other. Massive difference. There is however still a very low level hum which appears to be caused by Onkyo. Would placing an Iso Tek IsoPlug on both Tacimas make a difference? Anybody have any experience of this and whether it is likely to help? The Iso Teks don't cost a fortune but it's £60 I'd rather not spend if it won't make a difference.
Iso Tek IsoPlug - Mains Hum
- Thread starter Trahern
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Gerrardasnails
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- Sep 6, 2007
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Trahern:OK I have quite a lot of equipment plugged into 2 Tacima CS929s. When I added he second power amp at the weekend there was a terrible hum through the speakers. I then placed the pre-amp on one of the Tacimas and placed the power amps on the other. Massive difference. There is however still a very low level hum which appears to be caused by Onkyo. Would placing an Iso Tek IsoPlug on both Tacimas make a difference? Anybody have any experience of this and whether it is likely to help? The Iso Teks don't cost a fortune but it's £60 I'd rather not spend if it won't make a difference.
It didn't do anything for my system.
It didn't do anything for my system.
matengawhat
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- Aug 17, 2007
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have you got your the onkyo front pre outs connected to your pre amp with front speakers connected to power amps for home cinema use? I have the 876 connected to a MF A5 pre and two Arcam P35 power amps and also have a hum - not managed to beat it yet
if i turn to home cinema input on MF Amp with Onkyo off its very loud - if turn onkyo on it get quieter but can still hear over high frequencies if put ear close to speakers
i have mine plugged into two seperate merlin mains blocks into two different sockets - even bought new interconnects in hope of curing it, didn't work - also have iso plug - didn't work - onething i thoughts of is rf interference and thought about buying a load of plugs to fill the sockets in the back of the amp
only other thing I have not tried as isn't possible in my setup - it to plug them both in to the same mains block - incase its a mains loop problem somewhere - please post if you sort it!
if i turn to home cinema input on MF Amp with Onkyo off its very loud - if turn onkyo on it get quieter but can still hear over high frequencies if put ear close to speakers
i have mine plugged into two seperate merlin mains blocks into two different sockets - even bought new interconnects in hope of curing it, didn't work - also have iso plug - didn't work - onething i thoughts of is rf interference and thought about buying a load of plugs to fill the sockets in the back of the amp
only other thing I have not tried as isn't possible in my setup - it to plug them both in to the same mains block - incase its a mains loop problem somewhere - please post if you sort it!
Matengawhat the set-up you describe is exactly the one I use. I'm have front pre outs from the Onkyo into the AV inputs on the pre amp to make use of the bypass when watching movies and the centre pre out from the Onkyo directly into the power amps using a y-splitter. The pre amp is then connected to the power amps and the power amps feed the front and centre speakers which are of course now all bi-amped.
I have also plugged the Tacimas into separate mains sockets. I wonder whether separating the Onkyo onto a third mains socket (not that I have one) would help, it certainly made a very significant difference when I separated the 2 power amps from the pre amp?
The hum isn't terrible but it is irritating at least to me when everything else is working fine. Might move some plugs around and see if that helps.
I have also plugged the Tacimas into separate mains sockets. I wonder whether separating the Onkyo onto a third mains socket (not that I have one) would help, it certainly made a very significant difference when I separated the 2 power amps from the pre amp?
The hum isn't terrible but it is irritating at least to me when everything else is working fine. Might move some plugs around and see if that helps.
As I understand it, you are better pluging the boxes into the same socket. This reduces the size of any ground loop and should, therefore, minimise the hum. The theory relates to star grounding. I've not experienced any issues with ground loops smyself so have been unable to experiment.
If you'd like to read a little more on ground loops and why they occur, take a look at my power amp thread. The last post I wrote for that thread provides an outline of disconnecting networks and makes some statements around ground loops. Find the thread here.
Solutions? Well, to solve the problem you need to break the loop. There are a few very dangerous ways of doing this, which I wouldn't recommend, which focus on breaking the mains earth. Alternatively, you can look at breaking the loop at the interconnects e.g. take a look at this. I haven't tried this myself so can't comment on its quality.
You can also get hum introduced via interconnects running parallel to power cables. Again, I've not experienced this but I understand the hum occurs at a different frequency, so can be distinguished from ground loop hum.
Hope this helps or, at least, provides some avenues for further investigation/research.
If you'd like to read a little more on ground loops and why they occur, take a look at my power amp thread. The last post I wrote for that thread provides an outline of disconnecting networks and makes some statements around ground loops. Find the thread here.
Solutions? Well, to solve the problem you need to break the loop. There are a few very dangerous ways of doing this, which I wouldn't recommend, which focus on breaking the mains earth. Alternatively, you can look at breaking the loop at the interconnects e.g. take a look at this. I haven't tried this myself so can't comment on its quality.
You can also get hum introduced via interconnects running parallel to power cables. Again, I've not experienced this but I understand the hum occurs at a different frequency, so can be distinguished from ground loop hum.
Hope this helps or, at least, provides some avenues for further investigation/research.
matengawhat
Well-known member
- Aug 17, 2007
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What happens if you disconnect the antenna connections from your system? Some information on the net suggests that some parts of the system (TV, AV rec) typically get their ground level from the antenna rather than the mains, causing a difference (and hence a ground loop) with the other components.
I recently post the same issue but for me it was only happening when I have the airco unit connected:
http://community.whathifi.com/forums/404857/ShowThread.aspx#404857
I have found later on this post related the same issue, what a conincidence!!! that the three of us we had the same configuration, we were only amplifying the front spekers. Is it a conincidence, sure it is not.
But I have and advange, I am using an integrated amplifier not a sheer power amplifier for my fronts, so I have some extra imputs to check the noise without being conected to AVR.
I run to my Musical Fidelity A300 and I connected and ipod to it, and I switched the AirCo unit (it was the cause of the noise), and guess what?, cristal clear!.
For the sake of the science I connected the fronts straight to the AVR, and also no noise.
So the problems it is not the power amp itself nor the AVR, but sources from the configuration.
There's something wicked power-amplificating only the fronts!
Regards
http://community.whathifi.com/forums/404857/ShowThread.aspx#404857
I have found later on this post related the same issue, what a conincidence!!! that the three of us we had the same configuration, we were only amplifying the front spekers. Is it a conincidence, sure it is not.
But I have and advange, I am using an integrated amplifier not a sheer power amplifier for my fronts, so I have some extra imputs to check the noise without being conected to AVR.
I run to my Musical Fidelity A300 and I connected and ipod to it, and I switched the AirCo unit (it was the cause of the noise), and guess what?, cristal clear!.
For the sake of the science I connected the fronts straight to the AVR, and also no noise.
So the problems it is not the power amp itself nor the AVR, but sources from the configuration.
There's something wicked power-amplificating only the fronts!
Regards
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