Hissing amplifier in the highs

jeremie971 Posted messages 15 Status Member -  
jeremie971 Posted messages 15 Status Member -
Hello,

I have a SONY UDA-1 amplifier and a pair of Edifier R1700BT speakers.
A few days ago, I turned the volume up higher than usual on the amplifier.
Since then, a very unpleasant crackling noise has appeared. It is very intense at high frequencies.
The problem comes from the amplifier because when the speakers are not connected to the amplifier, there is no crackling, even at full volume.
Do you know what the problem is and how to fix it?

Thank you for taking the time to read my issue, and thank you in advance for your responses.

Configuration: Windows / Chrome 68.0.3440.106

5 answers

Jojolaguitare Posted messages 12012 Registration date   Status Member Last intervention   2 782
 
Hello.

Indeed! An amp without speakers means you can't hear any sound. Except for the humming of the transformer, and even then, if it's shielded, it's going to be hard to hear.
Plug a headset into the phones input without connecting the speakers and listen if you hear that fizzing.

>>> I turned the volume up higher than usual on the amp <<<

That's the hitch! At high volume, the tweeters don't handle peaks well, and often the voice coil of the driver heats up quickly and burns out. If the cut-off isn't immediate, this results in that fizzing.

If the headset works fine, for control, you will need to open your speakers and disconnect the + of the tweeters. If you no longer hear the fizzing, you'll understand the why and how.

See you later...

--
"Patience leads to success, haste leads to nothing."
1
trochp
 
Hi, Jojo caught me...
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Jojolaguitare Posted messages 12012 Registration date   Status Member Last intervention   2 782
 
Hello troch ;-)
Well, let's say I anticipated the hypothesis that you probably had in mind too.

See you later . . .
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jeremie971 Posted messages 15 Status Member 1
 
Hello,

Thank you very much for your very quick responses.
I understand your surprise when I said that I don't hear any crackling from the speakers when they're not connected to the amp.
In fact, since these are compact speakers, by connecting them directly to the PC I can hear something. And that's how I determined that the problem comes from the amp.
Because when they are connected to the PC without going through the amp, everything is fine.

Unfortunately, I do not have a 6.35mm jack headset available.
I will try to find a male 6.35mm to female 3.5mm adapter.

In the meantime, is there anything else to do?
1
trochp
 
Hi, I don't see how you can hear anything on it if the speakers are not plugged in!
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Jojolaguitare Posted messages 12012 Registration date   Status Member Last intervention   2 782
 
Hello.

Here is the explanation we were waiting for :)

Nothing to do... I'm afraid the hybrid amplifier integrated circuit has suffered during the power increase. Or another hypothesis: the switching power supply (given the limited space in the amp)
but that's a rare failure. I think more about the output stage (integrated amp).

I couldn't find the technical diagram of the printed circuit for this amp... Too bad

See you...

--
"Patience leads to good, haste leads to nothing"
0
jeremie971 Posted messages 15 Status Member 1
 
Okay, I understand
Thank you from the bottom of my heart for these answers!
I will find an adapter, I'll test it with a headset and I'll give you the result as soon as possible.

See you soon.
0