Troubleshoot advice, noise Lyngdorf and icepower.

[marcus_ec]

Ok need some mental support soon

I went to a hifi friend's today for troubleshooting and we were both gray haired when we were done.

We have noise when the amplifier is connected to the speakers. (only amp)

The noise stops when the amplifier is connected with xlr to the preamplifier. (Preamp off) and is boosted when the preamp is turned on. If I pull out a signal cable, the noise starts in a speaker again (the preamplifier is switched off)

So the noise goes away when it has the signal cable plugged in and the preamp is turned off.
The preamp are silent with his old Mark Levinson power amp.

Going crazy!!!

 

[marcus_ec]

Now i give up!

Today I assembled everything! No matter what I do, it's the same noise constantly. I've really tried one thing at a time and the last step was just power and I have noise right on the pins on the module.

Right here i tried grounding points.

And here the last step..

 

[BenjaminB]

Now i give up!

No, no, don't give up. Ground loops are know to make grown up men crying in despair.

But it most often not very difficult to find out, one just have to be extremely strictly systematic.
Above some measurements were suggested. Have you done those, and results are?

Todays pic is difficult to understand, why are the loudspeaker cables removed from the connectors? (for one of the loudspeaker outputs).

In your previous post you write

1) We have noise when the amplifier is connected to the speakers. (only amp)

2) The noise stops when the amplifier is connected with xlr to the preamplifier. (Preamp off) and 3) is boosted when the preamp is turned on. If I pull out a signal cable, the noise starts in a speaker again (the preamplifier is switched off)

So the noise goes away when it has the signal cable plugged in and the preamp is turned off.
The preamp are silent with his old Mark Levinson power amp.

1) is more or less expected. The open inputs then capture some white noise from the surrounding. (myself, I never turn on a power amp with open inputs. OK, most often nothing happens but still!). If you should try anything that should be with shortened inputs.

2) yep, when connecting a cable the input is no longer open. No noise is amplified. Expected.

3) probably a ground loop is started when the pre-amp is turned on. To find out why / where one has to make some measurements, alternatively some experiments (but those can be many!).

Have you tested with other XLR cables? Have you tested with the one you have but securing so that no contact between pin 1 and connector shield? As you were successful with the RCA connector (not sure what you did there) then that is an indication that the amp and pre-amp should be more isolated from each other.
Also, are you using power cables with ground connectors ? Those can easily create a ground loop which together where the XLR cable you have really closes the ground loop. You could _carefully_ test using power cables not connected to ground. VERY carefully ... try not to touch any chassis when testing this, and if so, only with one hand.

Do not give up, do systematic tests and measure, If you do not have a multi-meter, go get one. ~ $20 and up, not more.

 

[marcus_ec]

Have you tested with other XLR cables? YesHave you tested with the one you have but securing so that no contact between pin 1 and connector shield? As you were successful with the RCA connector (not sure what you did there) I have the same noise when i use RCA to XLR (Lyngdorf). I bought this cable to try my home cinema reciever (less noise) then that is an indication that the amp and pre-amp should be more isolated from each other.
Also, are you using power cables with ground connectors ? Yes Those can easily create a ground loop which together where the XLR cable you have really closes the ground loop. You could _carefully_ test using power cables not connected to ground. VERY carefully ... try not to touch any chassis when testing this, and if so, only with one hand.

I have also tried ungrounded outlets in my house with a extension cable (ungrounded living room) First preamp later poweramp.

Do not give up, do systematic tests and measure, If you do not have a multi-meter, go get one. ~ $20 and up, not more.

Right now i just want to listen to music...

 

[BenjaminB]

Hm, ... not so easy to perform a remote analysis. Fully understand your wish to just get this issue solved so you can just listen to your music. You will come to that! Patience and perseverance

The Lyngdorf pre-amp was tested with another power amp (PA), no noise. More than one reason for this, as this PA input sensitivity, gain etc., but also different grounding schemes.
Did you also test the IcePower with another pre-amp?

Have you tested shorting the input, ie connect both pin 3 and 2 to ground? From your test with the input cables this is likely to result in silence, but good to know. Easy to do if you open one XLR cable connector, as the one you showed in an earlier pic.

In any case, it seems the noise in not generated in the IcePower unit by itself, so it is either in the pre-amp or in the combo of the pre-amp and power amp. so .... when you connect the pre-amp to your PA are there anything else connected to the pre-amp? Have you tested removing all other units? (in my limited experience turntables often have some special grounding schemes).
This pre-amp of yours, Lyngdorf (unknown to me, googling didn't help much), what connections does it have and what does it do?


//BB

 

[marcus_ec]

Shorting pin 2-3 total silence. In this case only amp and my computer speakers.

 

[BenjaminB]

Shorting pin 2-3 total silence. In this case only amp and my computer speakers.

Perefct!

We now have:
a) when the XLR contact was replaced with a RCA then the noise level decreased. Not really sure how this was done but generally using unbalanced into a balanced input decreases the signal with 6 dB which could explain the lower noise you experienced.
b) when the ICEPower was connected to the pre-amp (turned off) then no noise.
c) shortening input to ICEPower also results in no noise.

These all indicate that the noise is not originating from you ICEPower power amplifier (PA). May still be so that the PA is part of a ground loop, but your test with another pair of XLR cables makes this less likely.

Thus ... your pre-amp. Guess some kind of sources are connected (? don't what Lyngdorf model you have and so on). You have tested with disconnecting all other units to the pre-amp? A further test could be to shorten an input to the pre-amp, select that as input source (in the selector on the pre-amp) and listen.

Again, most often issues like this are easy to fix when one has identified the reason. Worst scenario is probably that something inside the pre-amp creates the noise - then the pre-amp should be fixed. But first anything else should be eliminated!

//BB