Bypassing car amplifier SMPS for use in home

96tahoe · 23rd March 2008, 04:31 PM

Hi everyone, I want to power a car amp at home but instead of finding a high current DC power supply to feed it (which is totaly inefficient) how about bypassing the smps in the amp. Suppose the amp had 35 volt rail voltages I would insert a supply with that requirement into the board. Now the amp will be just like a home reciever. The amp will still have to be powered by 12vdc to provide basic functionality, so I would not have to construct any secondary supplies. Has anyone ever attempted this and was successfull? Any design obstscles? Thanks for any input.

richie00boy · 23rd March 2008, 04:45 PM

Why? It would be a mess (existing case would not be able to be used) and a bit of fiddling around. If you don't mind that then it should be easy enough unless the amp uses two tier rails or something.

Perry Babin · 23rd March 2008, 04:48 PM

If it's a simple amp and all voltages are produced by the main power transformer, it should work. One problem that you may have is the muting circuit. It's likely to be controlled by a circuit driven from the B+ and remote circuits.

If it's an amp that uses a secondary power supply to produce the low voltage (±15) and driver voltage, it will be more difficult.

96tahoe · 23rd March 2008, 05:11 PM

Thanks Perry, BTW your website is amazing! I have frequented your site for years! It has probably the most info on car audio on the entire web. I think bypassing the smps might prove to be too much work. I was looking for a cheap way to build an active PA system.

Perry Babin · 23rd March 2008, 05:13 PM

What make/model amp is it?

96tahoe · 23rd March 2008, 06:36 PM

It is a six year old four channel Pioneer, I think the model is GMX334. I also have a Legacy LA1020 (I know its crappy) that I don't mind experimenting on.

Perry Babin · 23rd March 2008, 08:34 PM

Both of those should be easy. If you want all of the muting and protection circuits to work, you may need to use a small 1-2 amp 12v supply to power B+ and remote. If you are not concerned with those circuits, they will be easy to bypass.

fizzard · 23rd March 2008, 08:50 PM

Just don't rely on the power supply capacitors in the amp to filter ripple at 60Hz. Make you understand the grounding of the amp, sometimes they can be funny. Some car amps ground signal to the chasis, and some don't.

mahmood · 3rd April 2008, 09:50 PM

Use this schematic it resultful . i use a simple of it in home .

23rd March 2008, 04:31 PM	#1
96tahoe diyAudio Member Join Date: Jan 2004 Location: b	Bypassing car amplifier SMPS for use in home Hi everyone, I want to power a car amp at home but instead of finding a high current DC power supply to feed it (which is totaly inefficient) how about bypassing the smps in the amp. Suppose the amp had 35 volt rail voltages I would insert a supply with that requirement into the board. Now the amp will be just like a home reciever. The amp will still have to be powered by 12vdc to provide basic functionality, so I would not have to construct any secondary supplies. Has anyone ever attempted this and was successfull? Any design obstscles? Thanks for any input.

23rd March 2008, 04:45 PM	#2
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Why? It would be a mess (existing case would not be able to be used) and a bit of fiddling around. If you don't mind that then it should be easy enough unless the amp uses two tier rails or something. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

23rd March 2008, 04:48 PM	#3
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If it's a simple amp and all voltages are produced by the main power transformer, it should work. One problem that you may have is the muting circuit. It's likely to be controlled by a circuit driven from the B+ and remote circuits. If it's an amp that uses a secondary power supply to produce the low voltage (±15) and driver voltage, it will be more difficult. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

23rd March 2008, 05:13 PM	#5
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	What make/model amp is it? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

23rd March 2008, 08:34 PM	#7
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Both of those should be easy. If you want all of the muting and protection circuits to work, you may need to use a small 1-2 amp 12v supply to power B+ and remote. If you are not concerned with those circuits, they will be easy to bypass. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links


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23rd March 2008, 05:11 PM	#4
96tahoe diyAudio Member Join Date: Jan 2004 Location: b	Thanks Perry, BTW your website is amazing! I have frequented your site for years! It has probably the most info on car audio on the entire web. I think bypassing the smps might prove to be too much work. I was looking for a cheap way to build an active PA system.

23rd March 2008, 06:36 PM	#6
96tahoe diyAudio Member Join Date: Jan 2004 Location: b	It is a six year old four channel Pioneer, I think the model is GMX334. I also have a Legacy LA1020 (I know its crappy) that I don't mind experimenting on.

23rd March 2008, 08:50 PM	#8
fizzard diyAudio Member Join Date: Nov 2006	Just don't rely on the power supply capacitors in the amp to filter ripple at 60Hz. Make you understand the grounding of the amp, sometimes they can be funny. Some car amps ground signal to the chasis, and some don't.

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