Merge two non-function sub amps in one?

Rosenbush · 3rd May 2011, 02:47 AM

Hi There
Can be possible to use only the input section from a Sunfire True Subwoofer and use a different amp stage?
I have a Tru sub with amp section damage, also a new Amp kit A/B 200 W.
Can I replace the amp section with the kit and make it work? In theory it should work, does any one try this before?
I'm planning to use an OSciloscope to find out the point where the signal goes in to the amp section.
Any tips?

cuallito · 3rd May 2011, 04:58 AM

Hard to say without knowing how both these exact amps work.

Making sure the DC component of the signal from each half is at the same level would be the important thing I would think.

They're useless anyway so I say go ahead and try it.

Rosenbush · 3rd May 2011, 01:27 PM

Hi Cuallito

Yes, I'll put an aditional PS for the amp section and use same GND. The Sunfire has a class D amp, but if I think is irrelevant if I took it before the signal goes in the amp section. The Sunfire has two principal boards, need to find out if they share some voltages betwen them before split them up.

wtk98 · 29th October 2011, 07:39 PM

Hi,
Probably you can, but I advise you to not.
I had the same problem, but after some net searching I decided to repair original PA.
True Sub has a 2 PCB, on first one are inputs, filters and controls and has an isolated ground. On the same board are circuits of voltage limiter, anti clip and other protection. This circuits are on a live ground and are optocoupler isolated from filters. Power for those circuits is from second board, where simple voltage doubler powered by separate winding of a small transformer. Both boards are connected via four pin header J1. From top: 1-signal from filters to PA, 2-GND LIVE!, 3- (-13V) from PA board to power protection circuits, 4- (+13V) as above. Also on PA board is Auto ON/OFF circuit. Sub has no power switch. The PA is powered directly from Voltage doubler rectifier of 120V AC giving +/- 165VDC or 330V total.
True Sub uses an enormous driver with giant magnet and very stiff cone. To move it Bob Carver uses amps of 1200W, 1500W, 2700W, 200W amp will not do the job. If you can try to fix it, it's a really great sub, sounds fantastic and is small.

3rd May 2011, 02:47 AM	#1
Rosenbush diyAudio Member Join Date: Oct 2010	Merge two non-function sub amps in one? Hi There Can be possible to use only the input section from a Sunfire True Subwoofer and use a different amp stage? I have a Tru sub with amp section damage, also a new Amp kit A/B 200 W. Can I replace the amp section with the kit and make it work? In theory it should work, does any one try this before? I'm planning to use an OSciloscope to find out the point where the signal goes in to the amp section. Any tips?

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3rd May 2011, 04:58 AM	#2
cuallito diyAudio Member Join Date: Apr 2004 Location: Milky Way	Hard to say without knowing how both these exact amps work. Making sure the DC component of the signal from each half is at the same level would be the important thing I would think. They're useless anyway so I say go ahead and try it.

3rd May 2011, 01:27 PM	#3
Rosenbush diyAudio Member Join Date: Oct 2010	Hi Cuallito Yes, I'll put an aditional PS for the amp section and use same GND. The Sunfire has a class D amp, but if I think is irrelevant if I took it before the signal goes in the amp section. The Sunfire has two principal boards, need to find out if they share some voltages betwen them before split them up.

29th October 2011, 07:39 PM	#4
wtk98 diyAudio Member Join Date: Jan 2009	Hi, Probably you can, but I advise you to not. I had the same problem, but after some net searching I decided to repair original PA. True Sub has a 2 PCB, on first one are inputs, filters and controls and has an isolated ground. On the same board are circuits of voltage limiter, anti clip and other protection. This circuits are on a live ground and are optocoupler isolated from filters. Power for those circuits is from second board, where simple voltage doubler powered by separate winding of a small transformer. Both boards are connected via four pin header J1. From top: 1-signal from filters to PA, 2-GND LIVE!, 3- (-13V) from PA board to power protection circuits, 4- (+13V) as above. Also on PA board is Auto ON/OFF circuit. Sub has no power switch. The PA is powered directly from Voltage doubler rectifier of 120V AC giving +/- 165VDC or 330V total. True Sub uses an enormous driver with giant magnet and very stiff cone. To move it Bob Carver uses amps of 1200W, 1500W, 2700W, 200W amp will not do the job. If you can try to fix it, it's a really great sub, sounds fantastic and is small.

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