Technics SU-V500 Feedback issues


Novice Member
Hello all, hope everyone's well.

I've recently purchased a second hand Technics SU-V500 Stereo Integrated Amplifier in full working condition according to the seller.

I've got it hooked up to 2x Technics SL1210's which are connected to a Pioneer mixer (grounded), which are all connected to the amplifier. My speakers are a pair of Sony SS-MF450H's.

My issue is whenever I turn on phono on the amplifier, I get a horrible hum, which increases in volume when turned up on the amp. I'm really struggling to get this fixed. Any ideas what the issue could be?

Thanks a lot for your time.


Distinguished Member
Technics are record decks.
The cartridges go to a Pioneer mixer pre-amp.
So why are you switching to phono on the Technics amplifier? There should (probably) be nothing connected to it?
THAT input is a high-gain RIAA curve input (lots of gain at low frequencies a lot less for high) intended for direct connection of a turntable cartridge.

The Pioneer should go into an AUX, CD, TUNER or similar high level flat response input on the amplifer.

Hum = ground loops normally but unclear to me in your case if that's the problem.


Novice Member
Because I am a moron.

I've changed it over to TUNER & it works perfectly, my headphone level issue is simultaneously fixed alongside the hum issue. Thank you very very much for your help & the small lesson, you have saved me!

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