wuzhi audio sorunu

[wax123]

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?

I removed it, I will try to install a new one with a different model, I will inform you. It will not work without them, should I remove it, it will remain empty.

 

[wax123]

Titreşimin nereden geldiğini bulamazsanız? Başka bir amfi alın veya daha iyi izole edilmiş ikinci bir kasa koyun. Başka bir fikir yok üzgünüm. Ama dürüst olmak gerekirse sadece o bobini sürerseniz sorununuzu gerçekten anlamıyorum ????? Çok az gürültü yapan bir deney mi? Kimin umurunda?

Kaldırdım, farklı bir modelle yenisini takmayı deneyeceğim, size bildireceğim. Onlar olmadan çalışmaz, kaldırırsam boş kalır.

 

[tomtoo]

Kaldırdım, farklı bir modelle yenisini takmayı deneyeceğim, size bildireceğim. Onlar olmadan çalışmaz, kaldırırsam boş kalır.

Sry language barrier.

 

[wax123]

Titreşimin nereden geldiğini bulamazsanız? Başka bir amfi alın veya daha iyi izole edilmiş ikinci bir kasa takın. Başka bir fikir yok üzgünüm. Ama dürüst olmak gerekirse sadece o bobini sürerseniz sorununuzu gerçekten anlamıyorum ????? Çok az gürültü yapan bir deney mi? Kimin umurunda?

Sağda gördüğünüz iki küçük kahverengi parça gürültüyü yapanlardır. Bunları devrede gördüğünüz kapasitörlerle değiştirdim ve gürültü durdu. Ancak çok ısınıyorlar. Ve bir süre sonra çıkış devresi kesiliyor. Kapasitörlerin ya şarj olduğunu ya da deşarj olduğunu ve devrenin kesildiğini düşünüyorum. Bunun yerine yönlü, kutupsuz bir kapasitör deneyeceğim. Ve tercihen polyester olan 100nF 400v'luk bir kapasitör denemeyi düşünüyorum.

 

[wax123]

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:

https://www.ti.com.cn/cn/lit/an/sloa119b/sloa119b.pdf

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.

The two small brown pieces you see on the right are the ones making the noise. I replaced them with the capacitors you see on the circuit and the noise stopped. But they get very hot. And after a while the output circuit is cut off. I think the capacitors are either charging or discharging and the circuit is cut off. I will try a directional, non-polar capacitor instead. And I am thinking of trying a 100nF 400v, preferably polyester.

 

[wax123]

Sry language barrier.

The two small brown pieces you see on the right are the ones making the noise. I replaced them with the capacitors you see on the circuit and the noise stopped. But they get very hot. And after a while the output circuit is cut off. I think the capacitors are either charging or discharging and the circuit is cut off. I will try a directional, non-polar capacitor instead. And I am thinking of trying a 100nF 400v, preferably polyester.

 

[tomtoo]

Cool that you could identify and even repair ! Have fun!

 

[AnalogSteph]

Are these 100 µF electrolytics I see? No wonder they get hot then, cutoff is at just a few kHz and they probably don't have super great ESR, aside from being polar and lowish voltage. I don't think 100 nF is enough given that the calculation says we want 560, and that's already giving a higher cutoff than you really want.

 

[Sokel]

Does yours singing too?
Read below:

Now I've heard it all

We have all seen lots of gear with noises of their own,right? Like transformers,etc. But have you ever heard a potentiometer singing? I mean this thing has a low level vrrrr noise which is constant and does not change with rotating it. To be more specific,nephew never listens to the uncle so...

www.audiosciencereview.com

You should be happy that at least yours do music

 

[wax123]

Are these 100 µF electrolytics I see? No wonder they get hot then, cutoff is at just a few kHz and they probably don't have super great ESR, aside from being polar and lowish voltage. I don't think 100 nF is enough given that the calculation says we want 560, and that's already giving a higher cutoff than you really want.

I'm thinking of using a 470nf mica capacitor and non-polar ones. I installed it as a test to see if it would block the sound. I had a 100nf polarized one so I installed them.

 

[AnalogSteph]

I had a 100nf polarized one so I installed them.

Not 100 nF, 100 µF (= 1000 x 100 nF)!

 

[wax123]

orange colored non-polar ceramic capacitors were installed as in the last figure pictures. The buzzing sound from the smd capacitors stopped. The circuit works without them. Information.
The same process was done on my 2x150w model in the picture on the right, but there is a very small sound and the reason is these tiny capacitors. (the ones I showed with the screwdriver tip)