# Amp itself making high pitched noises! Help!



## rc10mike (Mar 27, 2008)

I have a Zapco 1000.4 and the amp makes a somewhat loud high pitched squeal when bass notes hit, the speakers play fine however! Any ideas as to what this is?


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## Nelson de Leon (May 24, 2005)

Static?


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## goodstuff (Jan 9, 2008)

I'm willing to be it's something in the power supply. The noise doesn't go up and down when you rev the engine does it? I'd call zapco and ask about it.


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## 14642 (May 19, 2008)

Power transformer is loose. Open the amp and press on it gently to see if it stops or changes pitch. If so, either re-glue it or send the amp back


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## rc10mike (Mar 27, 2008)

Andy Wehmeyer said:


> Power transformer is loose. Open the amp and press on it gently to see if it stops or changes pitch. If so, either re-glue it or send the amp back


Can you explain more please? Loose?


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## Oliver (Jun 25, 2007)

Find the transformer and put some clear silicone under the edge and on top of the board [ tub and tile silicone will work [ $4.00 a tube or there abouts ]


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## vjgli (Nov 4, 2007)

a$$hole said:


> Find the transformer and put some clear silicone under the edge and on top of the board [ tub and tile silicone will work [ $4.00 a tube or there abouts ]


You sound like you are merely taking an educated guess. Shame on you.
If the Tranny is buzzing or making a mechanical noise; you have very few DIY options.

The main reason why they are making noise is because the power supply is switching at predesignated frequency. Thus, if the wires are not wound tightly, the wires will vibrate and create noise. 

#1) Using "tub/tile" silicone is too thick and will not flow in between the copper wires. Especially, inner vertical side of the toroid.

#2) "tub/tile" silicone cannot withstand hi-temp. Tranny can reach temp above 150 degrees Celcius. That's 302 degrees Fahrenheit!
You can actually force the silicone to become unstable and release toxic fumes into the air. 

The proper way to minimize is to remover the tranny and dip it into a tub of Hi-Temp stable laminate or epoxy.

So, there's really no simple solution to remove noise. 

Again, by you giving out this sort of remedy is very dangerous and irresponsible and may end up causing bodily harm.


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## rc10mike (Mar 27, 2008)

I have some black high temp RTV. Would that work?


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## KP (Nov 13, 2005)

tvrift said:


> I have a Zapco 1000.4 and the amp makes a somewhat loud high pitched squeal when bass notes hit, the speakers play fine however! Any ideas as to what this is?



If it is the DC1000.4 the hi/lo impedance switch just needs to be pressed.


Kirk


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## envisionelec (Dec 14, 2005)

a$$hole said:


> Find the transformer and put some clear silicone under the edge and on top of the board [ tub and tile silicone will work [ $4.00 a tube or there abouts ]


The noise is caused by magnetostriction and the winding/core relation is actually vibrating at some frequency well below the ultrasonic switching frequency.

Remove the transformer from the PCB and dip into a varnish, allowing it to fully drip-dry before reinstalling it.

Gooping silicone around the transformer is a kludge, at best. But transformers should never get to 150°C under normal operating conditions. Two things cause a transformer to stop working as it should: excessively high temperature and current saturation - and they are not mutually exclusive. Silicone has poor thermal characteristics and should never be gooped into the donut's "hole".  After all, heat must convect through there...

For many genuine ferrite (77) materials, the Curie point is ~200°C. The Curie temperature is the point where the transformer no longer has the capability to commutate current. At temperatures slightly below Tc, the permeability of the core drops, causing less current to pass from primary to secondary. Typically, you start popping switching components at this point. 

Slightly OT - but if you have an amp that "just doesn't seem to put out as much power anymore" you can bet that the transformer was overheated.


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## Graham9965 (Aug 2, 2020)

Mine is an infinity REF-704a 4 channel amp and it is making a high pitched feedback sound that DOES change pitch when I step on the gas..do u know why this is happening and how to fix it?


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