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Problem sa svetlostnim dimmerima i audio sistemom

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speedym
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Problem sa svetlostnim dimmerima i audio sistemom

Post by speedym » 08 Jul 2010, 20:58

Da li neko ima ideju u cemu je problem i kako da se resi - u dnevnoj sobi imam 2 'dimmera' za svetlo (umesto prekidaca imaju 'knob' koji se rotira i regulise jacinu svetla) koja, kada su u kranje levem (iskljuceno) i krajnje desnom polozaju (puna snaga svetla) ne prave problem. Medjutim, dok su u bilo kom polozaju izmedju, na zvucnicima se moze cuti reckavo caktanje. Intenzitet caktanja zavisi od polozaja dimmer knoba, dakle povecava se kada se krene od levog polozaja, negde na sredini je najjace, i smanjuje se kako dimmer ide ka punoj snazi svetla i na kraju, na punoj snazi svetla, nestaje.

Zanimljivo, slucajno sam otkrio da caktanje nestaje kada dopipnem sasiju Apogee Acoustics skretnice i ni jednog drugog uredjaja u sistemu. Takodje, caktanje se generise u ASUS Xonar D2 kartici u okviru desktop kompjutera koji je izvor zvuka i videa.

Situacija mi lici na ground loop, ali mi nije jasno kako to da intenzitet caktanja zavisi od polozaja dimmera. :-s

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PrekoBare
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Re: Problem sa svetlostnim dimmerima i audio sistemom

Post by PrekoBare » 09 Jul 2010, 17:56

Speedym, prema onome sto si opisao, nije u pitanju ground loop. Ground loop se cuje kao konstantno brundanje koje ima frekvenciju od 50-60Hz.
Tiristorski prekidaci emituju RF smetnje na koje su neki uredjaji manje a neki vise osetljivi.

Idealno, ne bi trebalo da imas tiristorske prekidace (dimmere) Ali posto moramo i komforno da zivimo a ne samo da slusamo muziku, predlazem ti da
probas da instaliras novi tiristorski prekidac pa da vidis da li ce i dalje biti smetnji. Ako ima, ono sto je Gerner predlozio, izolacioni trafo plus stavljanje
rasvete i audio napajanja na razlicite osigurace.
Frizideri i zamrzivaci takodje ubrizgavaju smetnje, proveri da se tiristori ne superponiraju na njih (cesto je frizider prikljucen na osigurac za svetlo)

Savetujem ti da napravis tabelu, sa kolonama

Potrosac - Osigurac - Ukljucen - Iskljucen

I da probas da gasis jedan po jedan potrosac i da vidis da li ima neke promene u zvuku. Za to ti treba pomagac, ti samo sedis i slusas a pomagac iskljucuje/ukljucuje. Moze da bude igranka bez prestanka dok se ne nadje krivac.
"Najbolje je neprijatelj dobrog"

Volter


Topic author
speedym
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Re: Problem sa svetlostnim dimmerima i audio sistemom

Post by speedym » 10 Jul 2010, 02:06

PrekoBare & Gerner, thanks for your detailed posts, they were quite insightful in how AC wiring for A/V eq. should be properly conducted.

I have solved the problem (for now) by removing the Apogee Acoustics active crossover (which was there temporarily, anyhow). For some reason, still unclear to me, that component introduced the noise problem between the dimmer and the HTPC (or perhaps simply made it audible).

I have also no idea why touching the chassis of Apogee Acoustics crossover removed the interference, and touching any other component chassis did not. :-k

Anyhow, I like the general idea of 1-1 transformers, and separating the A/V equipment to a different phase, and will consider doing it in the future.

I'm curious if the noise will return when I introduce Behringer DCX2496 active crossover to the system.. I guess time will tell.


Topic author
speedym
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Re: Problem sa svetlostnim dimmerima i audio sistemom

Post by speedym » 13 Jul 2010, 15:26

Gerner,

Yep, it's a mystery why grounding (by touching) the Apogee's chassis removed the clicking noise, and touching any other component chassis didn't. :-k I'm inclined to think the Apogee is overly sensitive, and has to be used with completely clean AC current. I didn't try any wire grounding since I had Apogee here for a very short time, ie. just for testing - I simply used either max or min dimmer setting which did not cause any interference whatsoever (which, as I found out later, is due to how dimmers with thyristors are built).

In general, I plan to use Behringer to discover the proper crossover frequencies for my speaker system, and then I intend to use it as a low pass / shelve up filter for the woofers only. Also, there will be a passive high pass filter for the mids/highs. (As a sidenote, I have separate amps for woofers and mids/highs, so that configuration is going to work out well.)

I fully agree with your signal harassment remark, moreover digital active crossover completely removes the effect of a DAC component. An that is very much unwanted, esp. if you have a hi-quality one.

If I find any more loops or bugs in the system esp. when I put the Behringer in, I'll post it in this thread. :good

Cheers!


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speedym
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Re: Problem sa svetlostnim dimmerima i audio sistemom

Post by speedym » 18 Jul 2010, 01:21

Short update: I've integrated Behringer DCX crossover into the system, & have no dimmer issues whatsoever. Apogee passive crossover had a bit softer sound though, but is quite sensitive to AC phase conditioning.

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