i have built an 8pcs opa 549 (bridge paralleled using drv134) using 24v-0-24v xformer and ive heard a hissing sound while playing music,its some kind of osscilation or EMI i guess???where does this came from cn somebody help me...
Check all ground connections(including signal input ground).
Check the connections from the drv134 to opa549. If the drv134 is not well connected,you will get hiss
What is your gain? It might be too high.
OPA549 has the max voltage list at +/-30,your supply voltage might be too high.
Check the connections from the drv134 to opa549. If the drv134 is not well connected,you will get hiss
What is your gain? It might be too high.
OPA549 has the max voltage list at +/-30,your supply voltage might be too high.
If you are using a PCB, make sure to scrub off any flux with alcohol.
I've run into this issue on several occasions. I guess you could call it "Flux Coupling" 😀
Hugh
I've run into this issue on several occasions. I guess you could call it "Flux Coupling" 😀
Hugh
tnx..i have fix it already i change the value of the resistor and it works well but because of a little heatsink i have u cnt even touch it because its too hot!!!..and its killing my xformer coz i only got 4700uf caps 50v...and whenever i use my large caps 120000uf 40v it kills the opa..but before the opa crashes u can hear a noisy sound it isnt a hum but its a loud sound like osscilation then my opa burns can u help me with this tnx a lot....😀 😀 😀
If you are not using the all metal(can)opa549 then the voltage from you transformer is too high(24*1.414=33.936). It is triggering shutdown.
i used the same heatsink as yours, single sided,10 inches, but no problem at all, the heatsink is warm but not hot, i used 24-0-24V,4amp, the sound is good,it really kicks my subwoofer.
Re: my opa 549
Nobody noticed yet that there's something missing on this board?
No PSU caps on the OPA549 chips?
arvin_ray said:
Nobody noticed yet that there's something missing on this board?
No PSU caps on the OPA549 chips?
Re: Re: my opa 549
my gain is 22 is it too high?
my PSU is separated..but for now i have no xformer(24-0-24v 5amps) for it was burn by those OPA's after i load that amp 2 ohms..sorry..
jaudio said:
my gain is 22 is it too high?
carlosfm said:
Nobody noticed yet that there's something missing on this board?
No PSU caps on the OPA549 chips?
my PSU is separated..but for now i have no xformer(24-0-24v 5amps) for it was burn by those OPA's after i load that amp 2 ohms..sorry..
1. Like Carlos said: Add psu coupling caps as close as possible to the chips.
2. Have you isolated the chips from the heatsink?
3. Those chips can only take +/-30V DC, measure your PSU voltages when not playing music.
4. Gain is too high! I would recommend a gain of 10-12 max.
2. Have you isolated the chips from the heatsink?
3. Those chips can only take +/-30V DC, measure your PSU voltages when not playing music.
4. Gain is too high! I would recommend a gain of 10-12 max.
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