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TPA3255 Reference Design Class D Amp GB

My 3d printed cases for XRK's TPA3255 amp and power supply are nearing completion. Just waiting on some connectors to arrive from Mouser.
 

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Founder of XSA-Labs
Joined 2012
Paid Member
Thanks, guys. The Warp-1 sounds unbelievable - playing Dark Side of the Moon from a TT with a premium Sumiko Blackbird MC cartridge, and new prototype LSA Phono-01 preamp, through a prototype LSA SET tube buffer preamp with volume control, which then drives the Warp-1 and playing on my 10F/RS225 TL speakers. This is one of the best renditions of "Money" I have ever heard. A couple of audio friends came by to listen to it and they both agree that it was a "goosebumps mind blowing" type of listening experience.

@Wineds: ok, cool - Amphenol PWF glass filled nylon series (12A) capable. I am used to seeing this is olive drab finished aluminum for aerospace connectors.
 
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Founder of XSA-Labs
Joined 2012
Paid Member
Hi Redjr,
The insides of the first unit before the wires were tidied up with zip ties is shown here:
TPA3255 Reference Design Class D Amp with PFFB

It’s not as neat as your build, LOL! But double 18ga high strand count silicone RC race car wiring is used between the PSU and amp and amp and binding posts.

The important thing is that this amp is absolutely silent with the source turned off. Cannot tell it is turned on with ears to speaker cone.
 
Founder of XSA-Labs
Joined 2012
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You can find all that in datasheet for non PFFB performance. Good rule of thumb is to take rail voltage and double it for BTL mode. But for SE mode, there is no doubling. Then subtract about 4v for mosfet dropout before clip. So 44vpp is the max swing. Divide that by 2.83 for max rms voltage. Square that and divide by load (8ohms I assume). This gives about 30w clean output. By clean, I mean well below 0.01% distortion.

Here is datasheet plot of distortion vs power for 51v rail in SE mode at 4ohms (grey line). There is no PFFB here so expect added 6dB improvement with PFFB and of 8ohms, curve will be below the 4ohm.
1640881560415.jpeg

You can see grey is about 0.01% at 30w. With PFFB probably will be ~0.007% at 48v for 30w into 8ohms.
 
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Founder of XSA-Labs
Joined 2012
Paid Member
Yes, there is a small Wurth micro connector in the middle of board. It can connect the clock sync lines. I assume you can use it in a bus for one master and multiple slaves. I have tested it with one master and one slave. A simple flip of the dip switch number 8 from master to slave puts a board in slave mode.

More info here:
https://www.diyaudio.com/community/...gn-class-d-amp-gb.340880/page-35#post-6387538
 
Founder of XSA-Labs
Joined 2012
Paid Member
Yes, there are some solder pad jumpers on the bottom that have to be configured for PBTL mode. Also flip a few dip switches. I have not personally tested it though but it follows the TI reference design so should work.

Yes, the SBAF tour is going quite well. It’s on the third stop I think. Those guys take a long time to perform listening tests and write a review. They are quite careful and methodical though.