Guitar Amp buzzes off of power inverter, will this filter work?

silentblackhat · 3rd November 2006, 05:19 AM

I just put a 700 watt power inverter in my car(its a modified sine wave inverter so i know its not 100% clean power). When i went to hook my guitar amp to it(the car isnt running so theres no engine noise in play). I am guessing that this buzzing is because of the inverter not putting out 100% clean power. I know that the amp is DC power instead of 120V AC. So i am wondering if I put DC power noise filters(consists of 2 caps and the inductor) on those power wires, if it will stop the bussing sound. The picture is below of the blue wire pointing to the set of wires that carry the DC current.

This is an Ibanez TB25R Guitar Amp.

Any help would be appreciated.

silentblackhat · 3rd November 2006, 06:40 AM

I am just wondering if I need to get a true sine wave inverter or if i could get thosefilters to work for me. I have the picture of a true sine wave compared to a modified sine wave from an inverter. I see that the filters might be able to help quiet the amp since the inductor would smooth out the 'edges' of the modified sine wave.

clem_o · 3rd November 2006, 12:45 PM

Take a look at your figure - the notice how the modified sine wave doesn't have the same PEAK voltage as the real sine wave. Filtering the modified sine so that it becomes a "clean" sine wave, if even close to successful, will result in an undervoltage for your amp - it will probably work, but don't expect full power from the amp...

Cheers

silentblackhat · 3rd November 2006, 02:13 PM

would I be able to just connect the 2 red wires together so i would only have to get 2 filters instead of 3?

clem_o · 4th November 2006, 10:12 AM

Howdy,

That certainly made me have a closer look...

The wires you are referring to are the output of the transformer inside your amplifier. The output of the transformer is AC, not DC. You can't use a DC filter there.

Cheers

silentblackhat · 4th November 2006, 07:19 PM

doesnt the amp run off of DC tho? would an A/C filter work there?
I am going to get a true sine wave inverter (later on tho, i have to save up for one, ill maybe get one off of ebay)because i think thats the problem where the voltage drops to zero for a period of time and then goes the other direction. would a true sine wave inverter solve my problem with the buzzing?

clem_o · 5th November 2006, 07:18 AM

Hi -

After the transformer, there are two bridge rectifiers (the two black squares in your first picture, right near the wires of the transformer where it enters the PCB). The output of those two bridge rectifiers would be DC.

If you do get a TRUE sine-wave inverter, yes, it would solve the problem.

Be wary though, I've seen claims to being 'true' sine wave, but the output waveform from the unit I tested looked pretty much like a modified sine you posted...

Cheers!

silentblackhat · 5th November 2006, 02:55 PM

so getting a cheap one off of ebay probably wont be a true sine wave? This is the one I was thinking of getting off of ebay.(link below)

http://www.powerbright.com/aps300.html

clem_o · 5th November 2006, 11:21 PM

It *looks* promising - there's a distortion spec of 4% on the manual. If that spec is true, it should be ok!

Cheers

silentblackhat · 6th November 2006, 03:15 AM

alright ill probably order it soon then. I will take it up to my local highschool(i graduated 3 years ago tho) because I know the physics teacher there so he would be able to use the osciliscope to test the wave form out. thanks for the help

3rd November 2006, 05:19 AM	#1
silentblackhat diyAudio Member Join Date: Jul 2004 Location: kansas	Guitar Amp buzzes off of power inverter, will this filter work? I just put a 700 watt power inverter in my car(its a modified sine wave inverter so i know its not 100% clean power). When i went to hook my guitar amp to it(the car isnt running so theres no engine noise in play). I am guessing that this buzzing is because of the inverter not putting out 100% clean power. I know that the amp is DC power instead of 120V AC. So i am wondering if I put DC power noise filters(consists of 2 caps and the inductor) on those power wires, if it will stop the bussing sound. The picture is below of the blue wire pointing to the set of wires that carry the DC current. This is an Ibanez TB25R Guitar Amp. Any help would be appreciated.

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3rd November 2006, 06:40 AM	#2
silentblackhat diyAudio Member Join Date: Jul 2004 Location: kansas	I am just wondering if I need to get a true sine wave inverter or if i could get thosefilters to work for me. I have the picture of a true sine wave compared to a modified sine wave from an inverter. I see that the filters might be able to help quiet the amp since the inductor would smooth out the 'edges' of the modified sine wave.

3rd November 2006, 12:45 PM	#3
clem_o diyAudio Member Join Date: Jun 2005 Location: Manila	Take a look at your figure - the notice how the modified sine wave doesn't have the same PEAK voltage as the real sine wave. Filtering the modified sine so that it becomes a "clean" sine wave, if even close to successful, will result in an undervoltage for your amp - it will probably work, but don't expect full power from the amp... Cheers

3rd November 2006, 02:13 PM	#4
silentblackhat diyAudio Member Join Date: Jul 2004 Location: kansas	would I be able to just connect the 2 red wires together so i would only have to get 2 filters instead of 3?

4th November 2006, 10:12 AM	#5
clem_o diyAudio Member Join Date: Jun 2005 Location: Manila	Howdy, That certainly made me have a closer look... The wires you are referring to are the output of the transformer inside your amplifier. The output of the transformer is AC, not DC. You can't use a DC filter there. Cheers

4th November 2006, 07:19 PM	#6
silentblackhat diyAudio Member Join Date: Jul 2004 Location: kansas	doesnt the amp run off of DC tho? would an A/C filter work there? I am going to get a true sine wave inverter (later on tho, i have to save up for one, ill maybe get one off of ebay)because i think thats the problem where the voltage drops to zero for a period of time and then goes the other direction. would a true sine wave inverter solve my problem with the buzzing?

5th November 2006, 07:18 AM	#7
clem_o diyAudio Member Join Date: Jun 2005 Location: Manila	Hi - After the transformer, there are two bridge rectifiers (the two black squares in your first picture, right near the wires of the transformer where it enters the PCB). The output of those two bridge rectifiers would be DC. If you do get a TRUE sine-wave inverter, yes, it would solve the problem. Be wary though, I've seen claims to being 'true' sine wave, but the output waveform from the unit I tested looked pretty much like a modified sine you posted... Cheers!

5th November 2006, 02:55 PM	#8
silentblackhat diyAudio Member Join Date: Jul 2004 Location: kansas	so getting a cheap one off of ebay probably wont be a true sine wave? This is the one I was thinking of getting off of ebay.(link below) http://www.powerbright.com/aps300.html

5th November 2006, 11:21 PM	#9
clem_o diyAudio Member Join Date: Jun 2005 Location: Manila	It looks promising - there's a distortion spec of 4% on the manual. If that spec is true, it should be ok! Cheers

6th November 2006, 03:15 AM	#10
silentblackhat diyAudio Member Join Date: Jul 2004 Location: kansas	alright ill probably order it soon then. I will take it up to my local highschool(i graduated 3 years ago tho) because I know the physics teacher there so he would be able to use the osciliscope to test the wave form out. thanks for the help

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