-
WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!
wuzhi audio sorunu
- Thread starter wax123
- Start date
staticV3
Grand Contributor
- Joined
- Aug 29, 2019
- Messages
- 11,434
- Likes
- 18,730
Wtf 
You could try to take it apart and find the precise sound source, then try to do something about, but I'm not sure if it's worth the effort.
Also, taking apart Amplifiers is inherently risky due to the capacitors potentially contained within.
You could try to take it apart and find the precise sound source, then try to do something about, but I'm not sure if it's worth the effort.
Also, taking apart Amplifiers is inherently risky due to the capacitors potentially contained within.
- Thread Starter
- #3
Yes, trying to replace all the parts is time consuming and risky.Wtf
You could try to take it apart and find the precise sound source, then try to do something about, but I'm not sure if it's worth the effort.
Also, taking apart Amplifiers is inherently risky due to the capacitors potentially contained within.
- Joined
- Oct 25, 2019
- Messages
- 12,091
- Likes
- 16,949
I fear we may never get to the bottom of this.
In fact I'm sure we won't .
Just look at it this way , you bought an amp . Turns out you got bonus speakers . Somewhere . In that little box .
- Thread Starter
- #6
There is a crackling sound of music
Attachments
Thx now we know more. If you now make a picture from the amp and not only from the case parts we would know even more.
- Thread Starter
- #8
Ok no high voltage here. You just can thouch the parts with your dry finger to see/hear what vibrates with the music. If you know what makes the sound evtl. some clue helps. just tell us first. Could be the heatsink on the chip. Or maybe a output induktor. You can listen and thouch to hear/see where it comes from. No danger.
- Thread Starter
- #10
I touched them all one by one, I took out the cooler but the sound is still there. I pressed and squeezed but it is still there. There are 2 black ones and the others.
AnalogSteph
Major Contributor
It is almost certainly some of the output filter components that are making the racket. Could be the inductors (see coil whine), but also the bigger brownish ceramic capacitors next to them (which are piezoelectric - yeah, like piezo beepers). That's what you get when things are designed to be as small and cheap as possible - I assume equivalent polyester film caps would have fit neither the board space nor the parts budget.
BTW, there is something missing from the left inductor. Was it like that when opened? The DC power jack also looks crooked. Some first-rate assembly quality right there...
BTW, there is something missing from the left inductor. Was it like that when opened? The DC power jack also looks crooked. Some first-rate assembly quality right there...
- Thread Starter
- #12
The left inductor was not like this when it was opened. I removed the outer part to test it. Even if the power input is direct, the sound is still there. I tried many adapters, 12v 2A, 24v 4A.
- Thread Starter
- #13
Can you give me an example picture of this? I'll try to change it. What should I buy?
AnalogSteph
Major Contributor
I was thinking something like WIMA MKP 2 series, 63 V rated should do easily if 24 V is the highest-voltage power supply you have. While SMD films do exist, the leaded variety may be more flexible in placement anyway. Which chip is this amp based on?
In order to determine the capacitance needed, you can either unsolder one and measure, or we can do the math based on some assumptions and this design document:
They have some example values but for a compromise 6 ohm load, those would be L = 22 µH and C = 1.2 µF. We know we have 10 µH inductors (yup, cost-cutting again), so in order to match these, we'll have to do the math in p.6 using (4) and (5). Since this is for a BTL circuit, we must enter half the load resistance, i.e. R_L = 3 ohms. Then
(4) <=> ω_0 = (R_L * √2)/L = 424.2 kHz
(5) C = 1/(ω_0 * R_L * √2) = 0.555... µF ~= 560 nF
Hmm. They're making MKP2 in either 0.47 or 0.68 µF (I would use the latter then), and in 63 V they're 8.5 mm wide x 7.2 mm long x 14 mm high. I think that's roughly the same footprint as the inductors but higher. (You can probably guess why they didn't want to use something like those - and then there's pricing.) I might consider the smaller MKS2 series but their impulse ratings seem insufficient for this use case.
In order to determine the capacitance needed, you can either unsolder one and measure, or we can do the math based on some assumptions and this design document:
They have some example values but for a compromise 6 ohm load, those would be L = 22 µH and C = 1.2 µF. We know we have 10 µH inductors (yup, cost-cutting again), so in order to match these, we'll have to do the math in p.6 using (4) and (5). Since this is for a BTL circuit, we must enter half the load resistance, i.e. R_L = 3 ohms. Then
(4) <=> ω_0 = (R_L * √2)/L = 424.2 kHz
(5) C = 1/(ω_0 * R_L * √2) = 0.555... µF ~= 560 nF
Hmm. They're making MKP2 in either 0.47 or 0.68 µF (I would use the latter then), and in 63 V they're 8.5 mm wide x 7.2 mm long x 14 mm high. I think that's roughly the same footprint as the inductors but higher. (You can probably guess why they didn't want to use something like those - and then there's pricing.) I might consider the smaller MKS2 series but their impulse ratings seem insufficient for this use case.
- Thread Starter
- #15
tpa3116d2
Attachments
Last edited:
- Thread Starter
- #17
Do you have any suggestions? I use these amps to drive Rodin coils.
Attachments
staticV3
Grand Contributor
- Joined
- Aug 29, 2019
- Messages
- 11,434
- Likes
- 18,730
Probably best to seek help from a licensed professional.
- Thread Starter
- #19
These amplifiers work well. The only problem is the music crackling sound coming from the body.
If you not find where the vibration comes from? Get another amp or put a second better isolated case around. No other idear sry. But to be honest if you just drive that coil i not realy get your proplem ????? A experiment that makes a tiny bit of noise? Who cares?
Last edited:
Similar threads
