EMC irradiation, how to reduce ??

[WolfgangL]

Hello
i got an LC audio zappulse amp, looks like vers 1.0. It got an upgrade with ferrite chokes and caps changed to 1,0µf plastic, so it looks now like Vers. 1.2.
This is my first class D amp and I am very impressed by this crystal clear strong sound. It drives audiostatic electrostatic panels and they work very well together
Problem is very strong irradiation in my Tuner when i switch on the zappulse, also in the next room in a receiver
I think it is EMC
What is a good way to reduce ?
In the attached file are some 1nF caps are added, will this work also with the older ZAP Version and would it help ?
What is your experience ? any ideas or suggestions?
thanks
Wolfgang

[ghemink]

Originally posted by WolfgangL
Hello
i got an LC audio zappulse amp, looks like vers 1.0. It got an upgrade with ferrite chokes and caps changed to 1,0µf plastic, so it looks now like Vers. 1.2.
This is my first class D amp and I am very impressed by this crystal clear strong sound. It drives audiostatic electrostatic panels and they work very well together
Problem is very strong irradiation in my Tuner when i switch on the zappulse, also in the next room in a receiver
I think it is EMC
What is a good way to reduce ?
In the attached file are some 1nF caps are added, will this work also with the older ZAP Version and would it help ?
What is your experience ? any ideas or suggestions?
thanks
Wolfgang

A good way to reduce? Get UcD :-)

Gertjan

[WolfgangL]

hello gertjan

this is unfortunately not the answer i am waiting for. I would like to solve this problem by DIYing not by changing the brand
I already read some parts of your discussion with Lars in Q + A zappulse thread ... you are UcD fan
Don´t forget it´s an old one, the first sold Version from ZAPP
Probably the most puls modulated electronics show this effect i.e mobile phone. And perhabs there is a simple solution

The distortion occurs when the second channel switch on
Power up the amp it needs 5-10 seconds, depending from volume and the first channel plays and there is no noise audible, then about 10-20 seconds later the second channel comes up and then there are strong distortions in my tuner. But only when i listen to the tuner, if playing CD there is no distortion audible
Perhabs it needs only covered by a better shielding
On low volume the zap doesn`t switch on playing, giving more volume it starts to play and reducing the vol it keeps playing on.
Already read about this in forum but unfortunaly couldn`t find this thread again

Wolfgang

[illusionxx]

Hello Wolfgang,

is you amplifier`s enclosure made of metal? If that`s the case you can connect it to earth ground to decrease electromagnetic radiation. A low impedance and especially low inductance connection to all parts of the enclosure is needed to make shure high frequency currents can be deverted to ground. If there are slots for ventilation it might also help to close them with some metallic material electrically connected to the rest of the case. But take care that the amp doesn`t get to hot if you do so.
Another opportunity is a line filter. A line filter for your tuner is much cheaper then one suitable for the current drawn by your amp. But a line filter for the amp will stop high-frequency interfering signals where they are produced.
Which action you have to take depends on the way the electromagnetic interference enters your tuner. In the worst case both steps are necessary. The best would be to try shielding first and to apply the filter only if shielding doesn`t help.

Good luck
illusionxx

[illusionxx]

Just saw in the wiring scheme that there is already a filter applied to the mains inlet. So i would just check the shielding of the case. The connection to the case could have declined because of oxidation or something. Maybe the speaker cables also emit electromagnetic radiation. In this case lowering the cut-off frequency of the output filter could help.

illusionxx

[classd4sure]

Hm. Could the second amp have some problem which gives it higher EMI?

Try it on its own and see, might be a problem with it.

Earlier ZAP's had poor EMI from what I understand, there may not be much you can do if it requires a better layout for instance.

See what LCaudio thinks.

[WolfgangL]

Hi
this morning I tested each channel separatly and there was NO more audible distortion in my tuner. Then let them work both in the same time, distortion is audible again. Perhaps some disharmonic in teamwork or they pulse in different frequencies ?
Next I put a filter in the main line ( there was no, I am ashamed, but I bought this amp on ebay just a few days ago ) an then distortion was gone, nearly perfect, distortion rapidly reduced !!!

And its a very old ZAPPULSE, first sold Version 1.0 !!!! Great

Also will do some better shielding, some 1nF caps etc. like its written in LCAudio site on " Newest page : RFI compliance " and see what happens.

Thanks to all for finding such an fast and straight way to a satisfying solution.

And not only to buy a new one $$$ , other brand , " UcD "

Wolfgang

[ghemink]

Originally posted by WolfgangL
hello gertjan

this is unfortunately not the answer i am waiting for. I would like to solve this problem by DIYing not by changing the brand
I already read some parts of your discussion with Lars in Q + A zappulse thread ... you are UcD fan
Don´t forget it´s an old one, the first sold Version from ZAPP
Probably the most puls modulated electronics show this effect i.e mobile phone. And perhabs there is a simple solution

The distortion occurs when the second channel switch on
Power up the amp it needs 5-10 seconds, depending from volume and the first channel plays and there is no noise audible, then about 10-20 seconds later the second channel comes up and then there are strong distortions in my tuner. But only when i listen to the tuner, if playing CD there is no distortion audible
Perhabs it needs only covered by a better shielding
On low volume the zap doesn`t switch on playing, giving more volume it starts to play and reducing the vol it keeps playing on.
Already read about this in forum but unfortunaly couldn`t find this thread again

Wolfgang

Hi Wolfgang,

I kind of new before posting my reply that my answer would not be of much help :-). At least it was a piece of advice based on experience. Actually I had 4 ZAPpulse 2.2SE modules. I tried to use them but they gave me several issues that made them unusable in my setup (active speakers with tweeter directly driven by amp). Trust me, I really wanted to use them as the 4 of them costed me close to $800. Then I dug out the wallet again to get the UcD180s, these performed very well without unwanted side effects, since then, yes, indeed, UcD fan, why, they just perform very well.

Best regards and good luck with the ZAPs, I saw in another post of you that you got rid off the interference problems.

Gertjan

[Jocko Homo]

Putting it in a metal box will not help if the radiaton is on the speaker leads. It usually is. Don't run any wires close to the output coil.

Other than that....the UcD suggestion sounds like Plan B.

Jocko

[matjans]

well, like everybody else said, put them in a metal box, don;t forget to ground the box; use an extra low pass filter directly at the speaker-out connectors on the zap modules; use something like ferrite clips on the speaker leads etc. You could also apply a ferrite clip to the power cord (which might also pick up rfi and lead it back to the net).

if the rf interference is only heard when the two modules are running at the same time, try shielding the modules from another (put them in separate metal boxes).

That's about all I can think of right now ...