Got a brand new amp. Is it normal for the reverb to buzz like this? (Video in description)

vipor3d

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Just got a brand new Supro Delta King 12, but noticed the reverb has a really loud buzz/hum that starts when the knob is at about 11 o'clock and gets louder as the reverb is increased. This doesn't seem normal to me. Am I wrong?

I didn't take the back off of the amp, but I was able to reach my hand in the back and ensured the reverb tank plugs were plugged in properly. I also cut off almost all nearby lights and power sources just to rule out any kind of interference but with no luck. Any ideas? Below is a video of what I'm hearing:

 

Wooly Fox

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Sounds like interference from somewhere, could even be in the wall socket you're using. Try a different wall socket if you can or even a different room to see if it continues at 11 o'clock.

I imagine someone will be along shortly to say "they all do that"...
 

vipor3d

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Sounds like interference from somewhere, could even be in the wall socket you're using. Try a different wall socket if you can or even a different room to see if it continues at 11 o'clock.

I imagine someone will be along shortly to say "they all do that"...
Just tried it in 2 different rooms (other than where the video was taken) with the same result. The buzz comes in right about 11 o'clock. Also, based on reviews I've watched/heard, the reverb I'm getting even when it is maxed isn't as heavy as it should be
 

Dacious

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Sounds to me like.a dud cable or connector. Could be inside the tank.Try unplugging and turning up just to isolate it from internal component.

If its new - warranty job.
 

vipor3d

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Sounds to me like.a dud cable or connector. Could be inside the tank.Try unplugging and turning up just to isolate it from internal component.

If its new - warranty job.
Tried unplugging the connectors and the loud hum was gone, but I was still getting a hiss type noise at the same position and higher on the knob.

Below is a video of what I'm hearing with it unplugged:



Re-seated the connectors and was still getting the hum. Reached out to Supro and they tried to tell me this was normal. But it's not because the hum makes the reverb unusable. Sounds like this might be a return to the store unit for me
 

J-Flanders

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The output transducer of the reverb tank is like an unshielded single coil.
In the vicinity of AC (the power transformer of the amp) it will pick up hum.
It's normal. If you were (able) to hold your guitar pickup in the same spot you'd have the same hum.

You can either:
- return the amp
- live with it
- rotate the power transformer or the reverb tank. Vertical instead of bottom down, or turn it 180°. The further the output coil of the reverb pan is away from the power transformer (or the mains AC coming into the amp, like the power cord or the on/off switch for example) the less hum you'll have.
- use longer (well shielded) rca cables and put the reverb pan further away outside the amp.
-Add some shielding around the reverb pan (rarely works well enough if it's so close to the source of the hum though)
- revoice the recovery stage of the reverb and use a more severe HP filter so less lows (hum) are in the reverb signal.

The hiss is there because the output signal from a reverb output coil is very tiny. It needs a lot of amplification/gain to bring it but to what the guitar signal is at that point. Lot's of gain equals hiss.
 




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