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Old 26th March 2013, 06:58 PM   #21
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Originally Posted by FoMoCo View Post
Without seeing the schematic, I can't say. I'd assume that it'll trash both the amp and the pre-amp to be safe.
Well, that wouldn't be any fun.

I don't have access to the schematics. Perhaps better to leave it alone and find something else to tinker with.

I do need to complete the chassis and optimize wiring, after all...
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Old 26th March 2013, 07:00 PM   #22
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That's my thought also. Any enclosure big enough to hold the big cap and preamp & amp boards will have enough room for the dual supplies. It already looks pretty good, just need to move the cap to the other side.
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Old 26th March 2013, 07:00 PM   #23
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It just seems to me like it would be more money/trouble than its worth. But I ain't your pa.

I have a more grown-up version of this basic idea. I use a computer power supply to run the tripath amp, I know everyone's going to freak out at that, but they are dirt cheap and have more current than you can shake a stick at.
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Old 26th March 2013, 07:05 PM   #24
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Originally Posted by alexmoose View Post
It just seems to me like it would be more money/trouble than its worth. But I ain't your pa.
As I said, I have all sorts of components and the objective would be to do it for free. The "trouble" is what I enjoy about this stuff. That's the beauty of doing this as a hobbiest/hacker. It is not time wasted or lost.

Quote:
I have a more grown-up version of this basic idea. I use a computer power supply to run the tripath amp, I know everyone's going to freak out at that, but they are dirt cheap and have more current than you can shake a stick at.
Whatever works!
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Old 26th March 2013, 07:08 PM   #25
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Originally Posted by sofaspud View Post
That's my thought also. Any enclosure big enough to hold the big cap and preamp & amp boards will have enough room for the dual supplies. It already looks pretty good, just need to move the cap to the other side.
The big cap will be mounted on top of the chassis (not inside) with that bracket holding it in place like on some old tube amps. The larger transformer will be mounted on top also, and there will be a hole cut out of the top plate to let the tube poke through.
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Old 26th March 2013, 07:23 PM   #26
JMFahey is offline JMFahey  Argentina
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1) connect transformer to 6A bridge to big filter cap.
Then bridge to filter cap legs.
*Then*, using separate red and black cables, as thick as possible (1mm to 1.8 mm , "translate" to AWG if you wish) feed whatever needs to be fed 12V.
It's bad practice bringing DC "down" and sending charging pulses "up" through the same wires.

2) load that filter cap with a 4 ohms 10 to 20W resistor or with (maybe easier to find) 1 or 2 car lamps , about 24 to 32W total, to see what yout PSU *actually* delivers under load.
If it drops to around 13V (quite possible) I think you can feed your Tripath with it.
Please google and post TA2020 datsheet to check.
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Old 26th March 2013, 07:27 PM   #27
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Originally Posted by JMFahey View Post
1) connect transformer to 6A bridge to big filter cap.
Then bridge to filter cap legs.
*Then*, using separate red and black cables, as thick as possible (1mm to 1.8 mm , "translate" to AWG if you wish) feed whatever needs to be fed 12V.
It's bad practice bringing DC "down" and sending charging pulses "up" through the same wires.

2) load that filter cap with a 4 ohms 10 to 20W resistor or with (maybe easier to find) 1 or 2 car lamps , about 24 to 32W total, to see what yout PSU *actually* delivers under load.
If it drops to around 13V (quite possible) I think you can feed your Tripath with it.
Please google and post TA2020 datsheet to check.
I'll have to go over this a few times before I understand exactly what to do, but thanks for the reply. And yes, the TA2020 can take up to 14.6v (actually, absolute maximum is 16v, but safe limit is 14.6).
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Old 26th March 2013, 07:31 PM   #28
FoMoCo is offline FoMoCo  United States
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Quote:
Originally Posted by JMFahey View Post
2) load that filter cap with a 4 ohms 10 to 20W resistor or with (maybe easier to find) 1 or 2 car lamps , about 24 to 32W total, to see what yout PSU *actually* delivers under load.
If it drops to around 13V (quite possible) I think you can feed your Tripath with it.
Just one problem. Music isn't a sine-wave. He will be drawing less current than max most of the time. If the line voltage is just a bit high and the amplifier not overdriven, the 16V max on the datasheet will be exceeded.
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Old 26th March 2013, 07:35 PM   #29
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Originally Posted by FoMoCo View Post
Just one problem. Music isn't a sine-wave. He will be drawing less current than max most of the time. If the line voltage is just a bit high and the amplifier not overdriven, the 16V max on the datasheet will be exceeded.
Good point. I'll be typically drawing much less than max. In fact, the amp is already getting a bit over 13 volts from the existing DC supply because it isn't loading it enough. Still safe, but not safe if that was 16v.
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Old 26th March 2013, 10:17 PM   #30
JMFahey is offline JMFahey  Argentina
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Fine enough.
Didn't know Voltage spec was *that* tight, that's why I asked.

*MY* favorite "car amp" chip is TDA2005, I have sold hundreds of 12V 7A battery powered Guitar/Mic amplifiers powered by them.
And although meant for a 12.6V battery, they work up to 18V, can stand 28V and short peaks of 40V, go figure.

Looks like often "old tech" is better

http://www.ozitronics.com/data/tda2005.pdf

Here's one of my biamplified TDA2005 + TDA2003 "FAHEY Callejero" amplifiers:

Click the image to open in full size.

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