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Class D Switching Power Amplifiers and Power D/A conversion

Tiny TAS5558 +TAS5624 "Power_DAC"+SMPS
Tiny TAS5558 +TAS5624 "Power_DAC"+SMPS
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Old 13th January 2019, 03:58 PM   #191
IVX is offline IVX  Ukraine
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Back to 3251 test, so far with no heatsink and 1.4W THD+N is 3 times higher than claimed in SLAA788A )) THD itself is close to SLAA788A THD+N result for TPA3251 i.e. .002% but my THD+N is .006%.. S/N with preamp 1VRMS sensitivity -110db(A), I think I lost somewhere 3db at least.
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Last edited by IVX; 13th January 2019 at 04:17 PM.
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Old 14th January 2019, 03:16 PM   #192
IVX is offline IVX  Ukraine
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The debugging of the stealth panel is an interesting process. I've printed front part of the heatsink, painted by cheap black spray(I hate cheap paints, they never do decent looking surface but I had no time to order good one), and here we go! YouTube
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Old 28th January 2019, 06:10 PM   #193
IVX is offline IVX  Ukraine
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I've found the way to improve S/N for TPA3251 amp, now S/N < -112db(A) at max volume, and < -114db(A) at middle volume setting. Still, have some clicking noise during amp's Off procedure, and ugly clipping behavior at speaker load and no load(seems phase margin too low). That self-oscillating noise around clipping is audible, hence not acceptable, funny that nobody cares about it and about Off click-noise as well in the Ti and their e2e forum, they are deaf? ))
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Old 9th February 2019, 12:04 PM   #194
IVX is offline IVX  Ukraine
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After some modification I've got not too bad clipping with tpa3251 in the post-fb mode, however, THD+N looks higher than original Ti's app-note(at speaker load THD, within measured range are better than THD+N up to 3 times). Signal/Noise ratio is still good -112db(A) at max gain(sensitivity 1VRMS). Finally, due to non-ideal clipping behavior of the tpa3251 in post-fb mode and 4ohm rated speaker load, the amp losing 15W of 1% THD power i.e. good clipped TAS5624 in the same conditions will produce about 130W. I personally don't hear a harshness after modification but probably somebody will. Frequency response at 20kHz 4 Ohm vs no load <.5db, hence post-fb doing its work
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Last edited by IVX; 9th February 2019 at 12:13 PM.
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Old 9th February 2019, 08:36 PM   #195
doctormord is offline doctormord  Germany
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What did you modified, current limit?
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Old 10th February 2019, 05:18 AM   #196
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no, there is 22k, I've changed post-fb network parts value.
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