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Class D Switching Power Amplifiers and Power D/A conversion

TI TPA3255EVM
TI TPA3255EVM
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Old 30th June 2019, 02:14 PM   #871
DPH is offline DPH  United States
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I believe a few users did go with 600w smps and two boards with no consequences, but, financially, the 300 watt smps are very reasonable so I, among most, chose that route. Also it allowed the flexibility to package these separately with short speaker cables in an active arrangement, but my stuff is in a mess, so I'm not doing that yet either, hah.
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Last edited by DPH; 30th June 2019 at 02:18 PM.
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Old 30th June 2019, 06:58 PM   #872
vacuphile is offline vacuphile  Netherlands
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Thanks Daniel.
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Old 21st July 2019, 09:03 PM   #873
DizRotus is offline DizRotus  United States
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Under pressure to host an 8/10/19 Southeast Michigan gathering of Klipschheads, I finally put my TI TPA3255EVM into a case. Without the ability to split the balanced signal from a Pono player, hooking up my four DIY Anarchy Exodus TH subs was problematic. Now the signal can be passed through to the pair of iNuke 1000s; each one powers a pair of subs.

While the 3255 project languished, I happily listened to a Wiener TPA3118, visible in its case next to the 3255. While I could be happy using that amp as my latest “final” 2-channel amp, listening to the 3255 again reminds me of the difference, even without the subs.
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File Type: jpg 9ED61DF6-D556-4784-B118-D2CC7821E0F6.jpg (1.00 MB, 270 views)
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Old 22nd July 2019, 08:04 AM   #874
vacuphile is offline vacuphile  Netherlands
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If you would mount it sideways so that the heatsink fins are vertical, cooling could be improved very very much.
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Old 16th August 2019, 09:56 AM   #875
chips666 is offline chips666  Belgium
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Default TPA3255EVM

Quote:
Originally Posted by linuxfan View Post
ABSNimes, regarding differential input to the 3255EVM board, in stereo BTL mode, there are two slightly different approaches;

i) connect to the J10 and J12 headers (or all 4x RCA connectors, which I consider confusing) -
your audio signals will still be buffered by the NE5532 opamps, but remain fully differential.

ii) connect to pins 11,13,15,17 & 21-GND of the J28 header (as member mboxler suggested)
your audio signals will then bypass the opamps, and go to the TPA3255 simply via a DC blocking cap.

Which approach sounds better will likely depend on whether your particular source device benefits from a buffer in the chain. I suggest you try i) first.
Check your configuration - you want the board in 2 x BTL mode, with differential inputs;

J5(M1), J6(M2) should be in the "0" or "L" position.
J21, J7, J8 should be open.
J4, J19 should be in the "DIFF" position.
J26 should be in the "C" position.
J27 should be in the "D" position.
S1 should be in the "NORMAL" position.

If this works OK, and you want to then try ii)
I understand that the opamps should be grounded, since they will then be unused, and might otherwise generate some noise (or heat).
Hello
Did someone try the second approach and what are your findings?
Enjoy...
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Old 22nd August 2019, 01:23 PM   #876
DizRotus is offline DizRotus  United States
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I used the first method; it sounds very good, so I stopped there and never tried the second method. It is hard to imagine that these old ears could perceive a difference, so I’ll stick with the way recommended by Texas Instruments.

I agree using four RCA connections seems counterintuitive. Nonetheless, that’s how I connected it before putting it in a case (XLR connectors replaced RCA). It helped me to remember that each balanced output consists of a + signal and a - signal. There is no common ground. One RCA pin delivers the + signal and the other RCA pin delivers the - signal, thus two RCAs are needed for each channel. The RCA collars are connected to the shielding, which is connected to ground.

The attached photos show a TPA3118 Wiener amp using four RCAs to accomplish what my 3255 does with a single XLR connector per channel.
Attached Images
File Type: jpeg 8781C3B2-A953-4641-90C6-F307354AC887.jpeg (216.9 KB, 99 views)
File Type: jpeg E5EBCF54-D48A-42B4-991F-C613FFF4571F.jpeg (178.4 KB, 94 views)
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Last edited by DizRotus; 22nd August 2019 at 01:41 PM.
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