Screeching from speakers with new amp

Truebrit · 11 Oct 2017 at 18:07

It even screeches if I touch the audio cable to the outside of the MOBO(onboard sound). I've tried moving the speakers to the other side of the room, no difference. It's better with the treble and bass turned all the way down, if I turn it up too far horrible bassy crackling.

I also tried it on my music computer running through a Native instruments sound card, same thing.

VIDEO:http://sendvid.com/8niefhhg

My speaker specs:
Max power 240 watts
Minimum power 5 watts
Nominal impedance 8 OHMS
Frequency response 35-22 KHZ
Sensitivity 92db per watt

Specification:
S/N: More than 70dB
Speaker impedance: 4 - 8 Ohm

Truebrit · 11 Oct 2017 at 19:29

I only had it on the PC case for the vid, it's usually on a wooden desk. With the PC output set to headphones I still get the same sound, it goes in sync with the volume knob, off, no noise etc. And it was £7.57

UK.

lude1962 said:
try taking the amp off the big metal comp case

amp isnt earthed may be something funny happening earth wise
may also be faulty its a £15 chinese job.

you also had the amp volume up too high - start with volume on 0 then turn up

edit its actually a £10.31 Chinese job

Truebrit · 12 Oct 2017 at 00:48

Just plugged my smartphone into it, sounds fine. What does that mean though? It's not my new amp, but both my PC's do it, I have ordered a 3.5mm to RCA cable, maybe that'll do something?

Marsman said:
Can't you connect a smartphone or tablet then try it?

That will go some way to determining whether there is a fault with the amp or not.

Truebrit · 14 Oct 2017 at 13:05

Ok thanks for the help, it's all sorted. Got the isolator which removed the horrible noise and the RCA cable I bought fixed the feedback, cheers.

EDIT: It's only partially fixed. With the noise of the PC running you can't here it anymore, but as soon as I shut it down there it is, but it is much better. It seems to make the exact tone of the PC fans running.

Truebrit · 15 Oct 2017 at 14:15

EDIT: It's only partially fixed. With the noise of the PC running you can't here it anymore, but as soon as I shut it down there it is, but it is much better. It seems to make the exact tone of the PC fans running. Would getting another isolator make an improvement, or is one the limit?

Marsman said:
That's good news.