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Old 16th February 2008, 11:57 PM   #1
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Default T-Amp and Pre Amp shared power problem

I am running a s.i. T-amps off a 12v sla battery (well Two actually) and am trying to add a line level pre amp to the system. Is it possible to run both the preamp and the tamp from the same 12v batteries? So far NO, when both the t amp and the pre amp are connected to separate batteries I get sound but hooked to the same batteries get power indicator leds but no sound. I can run the pre' and the t amp off separate batteries and it works. I've tried putting both batteries in parallel same no sound result. any advice on how to trouble shoot this and if it is possible to run both T and pre from the same 12v supply. the pre amp is a very simple one (stereo line level booster tc-780LC from phono preamps .com, built with a 553NP Op-Amp.
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Old 24th February 2008, 10:26 PM   #2
p01 is offline p01  Canada
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Same problem here. A GoVibe 5 and a SureElectronics Tripath board. I ditched the old power supplies in favor of a single one. Won`t work

With separate supplies or batteries, al is A-OK.

I still wonder why. Any ideas?
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Old 26th February 2008, 04:22 AM   #3
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Default bridged amp may be the problem

P O1
I could not tell if you were able to run both components from the same batteries, I am not able to. I have not seen if I can power both amp and pre amp from the same 12v battery but not have them in the same signal path, i.e. send a signal to, and thru the preamp from one source and send a second source directly to the amp. I don't know what this would tell me but I wonder if it would work. I get LEDs lit on both components but thats it.
It may, I suspect, be related to the “internal bridging of these small class d amps don't know howe it works but its a way of getting more power from a small chip and you cant have the outputs share the same return. there are a few threads that mention this, keep me posted
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Old 26th February 2008, 02:22 PM   #4
p01 is offline p01  Canada
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If the power supply is shared, the preamp (headphone amp) and the tripath amp both output signal from the same or different sources.

It could be the common ground that is causing problems when they are connected together, since in the preamp the power rails are split for the op-amp, and the tripath has digital and analog ground.
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