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Class D Switching Power Amplifiers and Power D/A conversion

TDA8954TH - XH-M252 board - anyone?
TDA8954TH - XH-M252 board - anyone?
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Old 19th November 2018, 09:00 AM   #11
tacoman5000 is offline tacoman5000
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Originally Posted by chermann View Post
just for the first try:
do not use the Class D amp without load
do not use your good speakers - dummy load = resistor

use some cheap chassis from old spakers or 2nd hand....

often the chinese board use fake caps...its marked normaly with better values --> voltage / capacity
Do you think replacing them with the same specs as the label on the capacitors could be a problem? I have no idea how fake their labels can be
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Old 19th November 2018, 09:05 AM   #12
chermann is offline chermann  Austria
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Originally Posted by tacoman5000 View Post
Do you think replacing them with the same specs as the label on the capacitors could be a problem? I have no idea how fake their labels can be
no there is no problem. i am very sensitive in the voltage of the fake caps because if you power up with the "labeled" voltage it might be that the fake caps explore !!!

with your caps there is no risk- just keep 2-3Volt under the max of the cap if you power up

chris
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Old 19th November 2018, 09:14 AM   #13
IVX is offline IVX  Ukraine
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tacoman5000, as I see he only measured the output voltage, it is not power measurement, which uses a resistor load as a standard. BTW, that IC has a quite low efficiency and without serious heatsink or fan you'll never get >150W per channel for a minute, rather 100W. The main problem for that particular board is cheap sendust inductors as I guess. Try to read black core marking please, to be sure if I'm right/wrong.
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Old 19th November 2018, 09:57 AM   #14
tacoman5000 is offline tacoman5000
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Quote:
Originally Posted by chermann View Post
no there is no problem. i am very sensitive in the voltage of the fake caps because if you power up with the "labeled" voltage it might be that the fake caps explore !!!

with your caps there is no risk- just keep 2-3Volt under the max of the cap if you power up

chris
Ah, alright thanks.
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Old 19th November 2018, 10:01 AM   #15
tacoman5000 is offline tacoman5000
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Originally Posted by IVX View Post
tacoman5000, as I see he only measured the output voltage, it is not power measurement, which uses a resistor load as a standard. BTW, that IC has a quite low efficiency and without serious heatsink or fan you'll never get >150W per channel for a minute, rather 100W. The main problem for that particular board is cheap sendust inductors as I guess. Try to read black core marking please, to be sure if I'm right/wrong.
I plan to mount this entire amplifier rig (with a bunch of other things) in a mini-ITX computer case with a large fan:

Click the image to open in full size.

Click the image to open in full size.


Sorry, I don't see any clear markings in the core. Any ideas on what else I can do to improve this amp?
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Old 19th November 2018, 10:59 AM   #16
dzwer is offline dzwer  Bulgaria
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Waiting for your response for the sound quality.
I saw that video, before opening the thread. There is some ringing in the square wave. Maybe some R-C snubbers can be added, to reduce the ringing.
For me the capacitance after the bridge rectifiers is too small - for me it's better to remove the two bridge rectifiers and supply the board directly with +/- DC voltages with at least 10000uF per rail.
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Old 19th November 2018, 12:47 PM   #17
IVX is offline IVX  Ukraine
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In my opinion, the sound quality of that IC is close to junk. At least without extra feedback loop with integrator, regarding formal specs as THD and S/N, it is low end for sure. I have posted the schematic(thread = TDA89** fasten belt) of my feedback-mod which I used for numerous caraudio brands years ago.
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Old 19th November 2018, 08:52 PM   #18
tacoman5000 is offline tacoman5000
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Originally Posted by dzwer View Post
Waiting for your response for the sound quality.
I saw that video, before opening the thread. There is some ringing in the square wave. Maybe some R-C snubbers can be added, to reduce the ringing.
For me the capacitance after the bridge rectifiers is too small - for me it's better to remove the two bridge rectifiers and supply the board directly with +/- DC voltages with at least 10000uF per rail.
Will update when I have tested these with speakers. I'm trying to look for dirt cheap speakers to test this amp with.
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Old 19th November 2018, 08:54 PM   #19
tacoman5000 is offline tacoman5000
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Originally Posted by IVX View Post
In my opinion, the sound quality of that IC is close to junk. At least without extra feedback loop with integrator, regarding formal specs as THD and S/N, it is low end for sure. I have posted the schematic(thread = TDA89** fasten belt) of my feedback-mod which I used for numerous caraudio brands years ago.
I probably won't even be able to use this amp anywhere near its full capabilities so I have no doubt I'd be getting clean power from it. Also, the anecdotal reports from other users about the sound have all been positive. I think that's good enough for me for the amount I spent on it
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Old 16th December 2018, 09:12 PM   #20
tacoman5000 is offline tacoman5000
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Can I wire this board to work in mono?
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