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jaimzness, Engineer
Category: Electronic Musical Instruments
Satisfied Customers: 117
Experience:  DAW and MIDI techniques. Keyboard and synthesizer programming. Electronic repair.
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I've bought a TDA8950TH 150W×2+250W Class D Digital

Customer Question

I've bought a TDA8950TH 150W×2+250W Class D Digital Amplifier off of Ebay and set the amp up using a 3 rail 25v-0v-25v Transformer. No probs there but setting up the Bass speaker I get a high frequency tone from the speaker. It is not loud or does it increase when using the volume controls. As soon as I disconnect one of the bass speaker wires the tone stops. The tone is not affected by the main left & right speaker channels. There are two big NOVER 10000uF 50V 105C AUDIO ELECTROLYTIC CAPACITORs Mounted at the rear of the circuit board. What then is causing the tone to emanate from just the bass speaker?

The one thing I did notice was the fact that when switching off the Amp there was a big 'clonk' on all speakers!! Another interesting fact that when I put the palm of my hand close [not touching the speaker cone] the high frequency disappears!! Also the tone sounds like a Fridge working!!!!..?

Submitted: 2 years ago.
Category: Electronic Musical Instruments
Expert:  adamd-mod replied 2 years ago.

Hello there,

I've been working hard to find a Professional to assist you with your question, but sometimes finding the right Professional can take a little longer than expected.

I wonder whether you're ok with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you.

Please note, I am just a moderator for this category, I can only try and find experts to help, I can't answer the question itself.

Thank you!


Customer: replied 2 years ago.

I am willing to wait further time to solve the problem.

As a point of interest.... a local retired radio electrician has mentioned that if the smoothing capacitors have stood a long while on the circuit board without working, they can leak and possibly cause this high frequency tonebut I am looking to find the actual cause, hence coming to you for a professional answer.

Expert:  adamd-mod replied 2 years ago.


We will continue to look for a Professional to assist you.

Thank you for your patience,