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Class D Switching Power Amplifiers and Power D/A conversion

What do the Coils do, in Amplifiers?
What do the Coils do, in Amplifiers?
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Old 18th September 2018, 12:00 PM   #21
Yatsushiro is offline Yatsushiro  France
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Quote:
Originally Posted by FauxFrench View Post
It seems like a fine board.
This board, usually called the YJ Blue/Black board has quite a history, allied to this forum!

It was effectively 'designed' (at least as far as schematic/layout) by DIYAudio member Danzz; his schematic was copied/interpreted and produced by Yuan Jing, followed by a host of Taiwanese clones.
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Old 18th September 2018, 12:40 PM   #22
spaceman5 is offline spaceman5  Israel
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Quote:
Originally Posted by Yatsushiro View Post
This board, usually called the YJ Blue/Black board has quite a history, allied to this forum!

It was effectively 'designed' (at least as far as schematic/layout) by DIYAudio member Danzz; his schematic was copied/interpreted and produced by Yuan Jing, followed by a host of Taiwanese clones.
Nice

Do you know if the use of Box Capacitors really contributes anything to the sound?
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Old 18th September 2018, 12:47 PM   #23
Yatsushiro is offline Yatsushiro  France
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Quote:
Originally Posted by spaceman5 View Post
Nice

Do you know if the use of Box Capacitors really contributes anything to the sound?
Not specifically so, I don't believe. The YJ board was arguably one of the most modified TPA3116 boards; whether that was due to it's popularity or it being a poor performer as standard is open to question.

This page offers a lot of empirical advice:

TPA3116D2 Boards
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Old 18th September 2018, 01:16 PM   #24
spaceman5 is offline spaceman5  Israel
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Quote:
Originally Posted by Yatsushiro View Post
Not specifically so, I don't believe.
The YJ board was arguably one of the most modified TPA3116 boards; whether that was due to it's popularity or it being a poor performer as standard is open to question.
I can add a third reason for this:
the fact that it's all thru-hole components..
It makes it much easier to change/connect to, rather than SMD components.


Quote:
Originally Posted by Yatsushiro View Post
This page offers a lot of empirical advice:

TPA3116D2 Boards
Amazing!
thank you, will go over it
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Old 19th September 2018, 05:47 PM   #25
steveu is offline steveu  United States
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1. In class-D amplifiers, the outputs have LC filters that convert a duty cycle to an analog Voltage. The main feature of UCD design is that feedback is taken after this filter so any core distortion is minimized.
2. Linear amps need a small output inductance "build-out" to prevent the speaker wires from shorting the high frequency feedback. ie the feedback is taken before this choke (and resistor) so that speaker + wire capacitance can not make the amplifier unstable.

3. TI has advertised "inductor-less" class-D amps, but they depend on the inductance of the speaker, and they are talking about bridged outputs that switch out of phase to reduce common mode currents that cause radio emissions. IE this is better than some other designs but not perfect, maybe "good enough" to pass radiate regulations.
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Old 19th September 2018, 06:24 PM   #26
spaceman5 is offline spaceman5  Israel
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I see.

So from the picture of the PCB,
it is 100% sure that the circuit does not have the (practically) needed inductors?

What are the 4 components that I marked earlier then?

Click the image to open in full size.
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Old 19th September 2018, 06:36 PM   #27
FauxFrench is offline FauxFrench  France
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@Yatsushiro: A fine overview of TPA3116 boards. The "YJ Blue/Black" board seems among the most serious implementations but is still sold at an attractive price (12$).

@steveu: Nice feature of the UCD concept. I only know the basic principle of UCD amplifiers, not their particular features. The "small output inductance" you mention for linear amplifiers, is that the one in the Thiele element?
PAM8403, PAM8610 and such low power amplifiers can function without an output filter. In my view, the TPA3116 is simply too powerful and low-impedance for such operation above 12V.

Last edited by FauxFrench; 19th September 2018 at 06:42 PM.
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Old 22nd September 2018, 04:43 AM   #28
steveu is offline steveu  United States
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If you mean "Le - Voice coil inductance measured in millihenries (mH) (measured at 1 kHz)" as used in Thiele/Small speaker parameters, no, that is the speaker coil inductance, not part of the amplifier.
Thiele/Small parameters - Wikipedia
Amplifiers that use feedback can not tolerate certain loads, so they include a "build-out" inductor and/or resistance as a minimum load impedance at high frequencies.
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Old 22nd September 2018, 07:21 AM   #29
FauxFrench is offline FauxFrench  France
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Quote:
Originally Posted by steveu View Post
If you mean "Le - Voice coil inductance measured in millihenries (mH) (measured at 1 kHz)" as used in Thiele/Small speaker parameters, no, that is the speaker coil inductance, not part of the amplifier.
Thiele/Small parameters - Wikipedia
Amplifiers that use feedback can not tolerate certain loads, so they include a "build-out" inductor and/or resistance as a minimum load impedance at high frequencies.
Many thanks for the link.
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