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Hi all, as you maybe have read I managed (with some help) to get my DAC playing yesterday. Yesterday when messing around I noticed some distortion trough the LH speaker only. It sounds like a mistuned radio. No complete snow but just, distortion. Also the bass is participating on this frequency. It happens spontaniously. It comes up and dissapears. Sometimes it takes longer than the other time (to pop up and disappear again.) Also sometimes (in between two songs) I hear a higher kind of distortion trough the RH speaker. It's more like when tuning the radio. From high to low and vice versa. So high that the bass is not participating. It seems that the DAC is picking up radio noise. Even with the volume to nearly zero. The volume knob does'nt seem to have any effect on the intensity of the distortion presented. I tried to push and pull the wires but nothing helps when it happens. Does anybody knows about this phenomenon? I will going to use shielding as I did with the Hypex amplifier (check the project gallery) and also the enclosure does'nt give much protection now it is open but is the DAC that sensitive? I don't believe so.... Edited by user Thursday, April 5, 2012 4:47:54 PM(UTC)
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When listening to the RH speaker with the music turned off and the PC (mediacenter) on I hear some small distortion almost like normal but also a humm through the Bass Cone.
Also the LH speaker gives more than normal distortion.
When turning the PC off the humm stops, but the other noises does not.
When the DAC is turned off the End Amplifier does not pass trough any distortion.
There is always a 'POP' sound present when whitching on and off the amplifier but I guess that's a different complaint...
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Noise: First of all - try with another source. You might have to isolate your PC from the DAC, easiest method is to use light (Toslink - http://www.twistedpearaudio.com/digital/torx.aspx). Another approach is to implement a pulse transformer into the SPDIF connection. Pop: The pop when turning on and off the Ncore is due to DC. The Ncore is DC coupled, any DC present at input it will pass to the speaker terminals - amplified by 26db. You have to trim the Legatos to 0.0v at DAC output. Measure without the Ncore connected. Be aware, it may drift as a function of temperature. You might even have to AC couple the DAC.
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Hi Avr300,
thanks for the reply again!
I tried with 2 sources. A normal CD player with toslink and the PC with Toslink. So I already have a Toslink module on the DAC and the source is galvanically declutched. Also the distortion on the LH channel appeared without any source connected to the DAC. So it must be internally.
I just swapped the DAC's at the IVY's. Let's see if the complaint travels along.
So far so good.
I have IVY pre-amp stages instead of Legato's. How can I trim them?
You mean with the Placid HD's? Can you please explain how that is to be done?
Thx in advance!
Jordo
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Too bad. LH channel is distorded again.... I now swapped the IVY's.... Let's see.... Next step is to doubt my own fabricate and swap the XLR interlinks.. Edited by user Friday, April 6, 2012 2:16:36 AM(UTC)
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Sorry, missed that. You can't trim the IVY. Check the DC at output terminals of the DAC. Try swapping the interconnects between the DAC and the Ncore. Does the problem follow the DAC or ... ? Pls. a picture, closeup, at the output connections. From the IVY to the output socket. Edited by user Friday, April 6, 2012 2:19:41 AM(UTC)
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Does'nt matter  After swapping the IVY the proble still excists on the LH channel. So I'm glad that the proble isn't caused by one of the components... I also swapped the interlinks, no help.. Can it be a grounding thing? O en where do I meassure for DAC output DC? Edited by user Friday, April 6, 2012 2:23:47 AM(UTC)
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Then your problem lays further upstream. Problem with the Ncore ? edit- that an awful lot of ground connection. What are they doing there ? Edited by user Friday, April 6, 2012 2:34:23 AM(UTC)
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Yeah, I'm using the star ground principle.
Pin 1 is directly grounded there to the chassis.
The housing of the XLR does also have a grounding point which I connected to the chassis.
For the SE output I choosed to make a twisted pair and ground the IVY there.
There is one line comming from the RH XLR connector connecting the stars and one line going to the main star to earth...
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The distortion came up again.
I turned off the DAC and some small noise continued trough the speaker.
When removing the LH interlink the sound dissapeared.
I will leave the Hypex on for now with the interlink connected. See what happens.
After that I will install the Lyngdorf again to see if the same problem excists.
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I can't comment the use of the 2 SE outputs when running dual mono - simply because I don't know - but are you sure that's the correct way to connect the dual mono configuration to balanced output.
I only ask because I don't know.
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Sounds to me as your Ncore are picking up some RF.. ?
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If I lay my ear against the LH speaker with the DAC turned off, the Hypex on and the interlink installed I hear the same kind of distortion but not as loud as it sometimes does with the DAC on. If I detach the interlink the level of distortion is dimmed but still a little bit can be heard. If I do the same with the RH speaker no distortion is heard. I connected the Hypex the same way. Let come up with some pictures..... Jordo attached the following image(s): Hypex%20af%208[1].jpg (247kb) downloaded 108 time(s).You cannot view/download attachments. Try to login or register.
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avr300 wrote:Sounds to me as your Ncore are picking up some RF.. ? Nearly impossible.. All the shielding that I used!! :)
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Unplug interconnect right at the Ncore, still noise ?
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avr300 wrote:Unplug interconnect right at the Ncore, still noise ? You will always see. No noise anymore. Lets try again... I do have to mention that about 2 weeks ago the Hypex LH channel did sounded some softer than the RH channel. After cleaning the plugs and looking around a little it didn't came back but it was certainly no noise comming from the LH channel..
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Are you using proper XLR plugs and sockets (read Neutrik).
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Yes I use Neutriks.
I'm playing for 15 minutes now and the problem still did not re-appeared.
I came up with another fascinating issue.
We might have concentrated on the wrong channel because left and right seem to be crossed...
If I mute the LH channel on the PC, the RH speaker is dimmed.... strange.
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See that's easy to cure...
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