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Need some help with an amp.

Once again, I need some information/help. I just got an Aragon 2004 from ebay. I am getting some humming/buzzing from the speakers. It is louder from the left speaker than it is from the right.

I disconnected everything, unplugged everything except the amp and the left the speakers connected and I'm still getting a hum. So, I plugged everything back in.

Now, for some observations.

1. Everything was plugged in and connected. My preamp was in standby. The switch on the amp was off. I unplugged the interconnects from the amp, so that amp is sitting there, plugged in with the speakers connected with the switch off and nothing hooked up to it in terms of interconnects. I grabbed an interconnect and got a loud hum from one of the speakers. The only thing that the interconnect was connected to was the preamp (NOT the amp).

2. I went to plug the interconnects back into the amp. The preamp is still in standby and the switch on the amp is off. With one of the interconnect plugs in my hand, I was reaching behind the amp to plug it in, my bare arm touched the amp and I got a little shock. Not a big one, but I can definitely feel a small current.

3. With the preamp in standby and the switch on the amp off and the interconnects disconnected from the amp, I touched my bare arm on the case of the amp and grabbed the connector on the interconnect with my other hand and felt the "shock" on my bare arm.

Can anyone tell me what's up?

Thanks.
tonyangel
ghs
25 posts
 
I would start all over again, unplug everything and have your amp and speaker connected. Short the inputs to you amp so that there will be no external signal introduced to you amp. Turn amp on and listen for the buzz, if the buzz is still there I would think the amp is the problem, if the buzz is gone I would plug each component in one at a time, to find the problem. When you connect cables or do anything with cabling I would not only use your mute or standby switch but I would tune everything off for safety. The voltage difference between equipment is a grounding problem which could be external or internal to one of your components, could be part of the problem but I would start with the sequence that I mentioned. To clarify the above if the amp is with out noise hook the preamp up without any components plug into it check the buzz and continue until you find the problem.
buconero117
2,311 posts
 
Ship it back and get paypal to refund your money.
hifihvn
943 posts
 
First of all, let the seller know about the problem. Handle this however you want.

If you have a digital multimeter and know what your doing, you could check the amp and preamp to a known good ground. This would at least tell you where the voltage is coming from.

The hum being louder in one channel doesn't sound normal either IMO.

The voltage being present on the amps cabinet can be dangerous. It could be capacitance somewhere causing it, or something that may have been worked on. Sometimes some amps do have a small voltage on them from moisture if the amp was cool, and can have condensation in them also.

If the amp has a grounded plug, make sure the outlet is properly grounded. If it just has a two prong plug, try reversing it in the outlet, if the prongs (plug) are the same size, allowing the reversal to be done, plugging it in. Check and try the preamp for the same (plug reversal).

If you try reconnecting this equipment, make sure you unplug everything (from outlets) first, before making, or changing any connection. With this voltage difference, if you plug something in and the center pin (RCA) makes contact first, before the outer shield does, it will feed that voltage to the delicate transistors (amp or preamp) and damage them. So be careful with this, and most important, make sure you don't get shocked.

Some amps will hum with nothing plugged in them. A shorting plug (RCA) on the inputs of the amp will prevent this. Some people make their own (the center pin is shorted to the shield), or you can buy some like these in this link.[http://www.mcmelectronics.com/product/27-5335&scode=GS111&CAWELAID=240971936]
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