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Class D Switching Power Amplifiers and Power D/A conversion

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Old 3rd May 2013, 02:36 PM   #231
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Default Creative PS

Found that Creative Labs makes this power supply for their subwoofer. I've seen several on EBay and surplus sites.
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Old 3rd May 2013, 05:06 PM   #232
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Is it AC or DC out? It looks like the case doesn't specify.
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Old 5th May 2013, 06:21 AM   #233
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I was contemplating how the Lepai executes the use of the TA2020 chip versus how Tripath shows how in the schematic in their datasheet and was wondering what is the purpose of the transistors in the Lepai? From what I can trace and what little I know, it seems that they are part of the power side of the circuit but I haven't a clue as to how they are used.

Anyone know?
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Old 6th May 2013, 08:01 PM   #234
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I do believe this thread is dead.
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Old 6th May 2013, 08:19 PM   #235
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Why do you say that?
My guess is no one knows the purpose of the transistors. I sure don't. My guess is they are part of the tone circuitry, or maybe function as power supply switching to other parts of the amp.
Someone with a dead Lepai ought to use it to trace out a circuit on paper. I'm not willing to do without listening to mine or I would do it.
BTW, that tilde on the Creative Labs ps strongly suggests it is AC out.
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Old 6th May 2013, 09:01 PM   #236
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I say it primarily because it's only you and myself posting.

I did do some more tracing and they are tied into the "fault" and "mute" pins on the IC. Best guess is that they are for IC protection or to lessen the turn-on thump.

I am posting a old schematic from the first version of this amp. It was gave me some insight into what the transistors do.

Yea...I was guessing it was AC out and the rest of the power circuitry is inside the sub. If it is AC out, once rectified to DC, the voltage will increase to something that is to high and would need to be reduced. Diodes?
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Last edited by THUMP LUMP; 6th May 2013 at 09:03 PM.
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Old 7th May 2013, 05:36 PM   #237
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Having already gotten a 4700uf power cap, gold binding posts and 2.2uf Audyn input caps from PE, I finally just ordered Wurth 10uh 4.7amp inductors, Wima .47uf polyester film caps for the output side, and Switchcraft gold RCA jacks, from Mouser.

I have also bead blasted the top of the case to remove the lettering and have rubbed it back out with 400 wet/dry sandpaper. It gives it a nice brushed look. I am also making some new end plates to accommodate the binding posts, new RCA jacks, and no tone controls. These will have a finish like the top of the case. I am getting rid of the lighted ring around the volume control and instead, using a single LED coming through the front to show it is ON. I am also going to machine a new aluminum volume knob and epoxy one of the old tone knobs inside for the splined insert.

I will post some pics soon.
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Old 7th May 2013, 10:06 PM   #238
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Quote:
Originally Posted by THUMP LUMP View Post
Having already gotten a 4700uf power cap, gold binding posts and 2.2uf Audyn input caps from PE, I finally just ordered Wurth 10uh 4.7amp inductors, Wima .47uf polyester film caps for the output side, and Switchcraft gold RCA jacks, from Mouser.

I have also bead blasted the top of the case to remove the lettering and have rubbed it back out with 400 wet/dry sandpaper. It gives it a nice brushed look. I am also making some new end plates to accommodate the binding posts, new RCA jacks, and no tone controls. These will have a finish like the top of the case. I am getting rid of the lighted ring around the volume control and instead, using a single LED coming through the front to show it is ON. I am also going to machine a new aluminum volume knob and epoxy one of the old tone knobs inside for the splined insert.

I will post some pics soon.
Sounds like where I am with my little project. It's a lot of fun.

I made new end plates, replaced the input caps with Epcos PP caps. Added 2x 5600uF caps for power, I will be winding new inductors soon, replaced spring terminals with banana jacks, added gold RCAs, removed the tone controls... Etc. I'll post some pics of Frankenpai soon.
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Old 9th May 2013, 04:50 PM   #239
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Here's a pic of the mock up of the front. Machined aluminum knob, stock switch and there will be a LED on the right hand side to show "ON".
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Old 11th May 2013, 03:11 AM   #240
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Stripped and ready for the good stuff. Wima caps, Wurth inductors, and Switchcraft RCA jacks should be here tomorrow.
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File Type: jpg TA2020 PCB TOP.JPG (204.8 KB, 209 views)
File Type: jpg TA2020 PCB BOTTOM.JPG (135.7 KB, 207 views)
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