VS1053 low audio level

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Orionis
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VS1053 low audio level

Post by Orionis » Mon 2013-11-04 17:37

Hi, I'm new to this forum.
I just finished a very simple project using this chip (by mean of a Sparkfun board module) in MIDI standalone mode.
Everything is ok but the output level is quite low.
From the datasheet (page 8):
Full Scale Output Voltage (Peak-to-peak) 1.64 1.851 2.06 Vpp
What I measure, on both channels, is about 0.3Vpp, superimposed to a constant high frequency noise level of about 50mV.
Any idea ? Could it be correct?


Could someone explain with different words the meaning of this note under the Analog Characteristic table:
3.0 volts can be achieved with +-to-+ wiring for mono difference sound.
What does it means the cryptic "+-to-+" ?

Thanks

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pasi
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Re: VS1053 low audio level

Post by pasi » Wed 2013-11-06 15:54

Orionis wrote:What I measure, on both channels, is about 0.3Vpp, superimposed to a constant high frequency noise level of about 50mV.
If you measure the headphone output, the hf noise is probably the modulator noise, which is not audible in headphones. For line output you should use an additional low-pass filter.

The actual output level of audio in RT-midi mode depends on channel and master volumes, note velocity, the frequency and number of notes, and also the instrument. You should be able to increase the output volume using the appropriate MIDI messages.
Orionis wrote:What does it means the cryptic "+-to-+" ?
When you connect between Left and Right outputs, what you get out is the difference of the channels. In SCI_MODE there is a bit SM_DIFF, which inverts the other output channel. So, for mono signal you get double the voltage difference between L and R compared to between L/R and GBUF.
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Orionis
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Re: VS1053 low audio level

Post by Orionis » Wed 2013-11-06 16:29

Thank you Pasi,
pasi wrote:If you measure the headphone output, the hf noise is probably the modulator noise, which is not audible in headphones. For line output you should use an additional low-pass filter.
I did it, that's ok.
pasi wrote:The actual output level of audio in RT-midi mode depends on channel and master volumes, note velocity, the frequency and number of notes, and also the instrument. You should be able to increase the output volume using the appropriate MIDI messages.
This is true, but even at max level, max velocity and with a 'strong' instrument (Percussion Organ), single note, I have only 0.6Vpp. I inserted a filtered preamp, so now it is ok.

pasi wrote:When you connect between Left and Right outputs, what you get out is the difference of the channels. In SCI_MODE there is a bit SM_DIFF, which inverts the other output channel. So, for mono signal you get double the voltage difference between L and R compared to between L/R and GBUF.
This does not comply with my measurement; according to my (old) oscilloscope, the L & R output are normally in phase, so a summing amplifier should double the output.
Anyway, this is not anymore relevant since I fixed the output level and I can use only one of the two outputs.

Question: in MIDI mode the two outputs are in reality two mono identical signals, right ?

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pasi
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Re: VS1053 low audio level

Post by pasi » Wed 2013-11-06 16:47

Channel panning is implemented, so there is some difference between left and right channels even in MIDI. However, midi reverb is mono. EarSpeaker is stereo, but you probably would not want to use that if you only have one output.

Yes, left and right are in-phase normally, for differential output (usually only used with a direct speaker connection) you need to specifically set the SM_DIFF bit.
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idw001
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Re: VS1053 low audio level

Post by idw001 » Thu 2015-02-19 17:30

pasi wrote:
When you connect between Left and Right outputs, what you get out is the difference of the channels. In SCI_MODE there is a bit SM_DIFF, which inverts the other output channel. So, for mono signal you get double the voltage difference between L and R compared to between L/R and GBUF.
If I use this method for feeding a mono amplifier, what are the implications for the output circuit? Do I still need blocking capacitors now that GBUF is not involved?

Thanks,

Ian

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pasi
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Re: VS1053 low audio level

Post by pasi » Wed 2015-02-25 14:50

If you used either LEFT or RIGHT as the ground and the other signal as audio with an external amplifier, you would still need DC-block capacitors to prevent ground loops.

However, you generally don't need DC-block for on-board amplifiers, because they do not create ground loops.
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lorenzo
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Re: VS1053 low audio level

Post by lorenzo » Mon 2015-03-09 18:48

Hi!
I have a question a little related with this post.
I use a VS8053 and I'm wondering if my idea to connect the L and R to the differential amplifier from the Texas Instruments - TPA2013D1 is a good idea. (I plan to set the bit SM_DIFF to permit this design to work).

I will put the resistor (10R) and capacitor (47n) between GBUF and GND. Is that enough?

I plan also to put a resistor of 1K near the TPA2013D1 between L and R. Is a good idea to reduce the cross-talking of the digital nearby line?

Thank you

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Henrik
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Re: VS1053 low audio level

Post by Henrik » Tue 2015-03-10 12:41

lorenzo wrote:Hi!
I have a question a little related with this post.
I use a VS8053 and I'm wondering if my idea to connect the L and R to the differential amplifier from the Texas Instruments - TPA2013D1 is a good idea. (I plan to set the bit SM_DIFF to permit this design to work).
Yes, that is helpful for minimizing noise and crosstalk.
lorenzo wrote:I will put the resistor (10R) and capacitor (47n) between GBUF and GND. Is that enough?
Yes.
lorenzo wrote:I plan also to put a resistor of 1K near the TPA2013D1 between L and R. Is a good idea to reduce the cross-talking of the digital nearby line?
I don't think that will be necessary. Note that when you set SM_DIFF, your signal is differential and that already makes you line pretty immune to crosstalk, as long as the L and R lines are adjacent to each other.

Kind regards,
- Henrik
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arlaor
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Re: VS1053 low audio level

Post by arlaor » Wed 2019-04-24 17:42

Henrik wrote:
Tue 2015-03-10 12:41
lorenzo wrote:Hi!
I have a question a little related with this post.
I use a VS8053 and I'm wondering if my idea to connect the L and R to the differential amplifier from the Texas Instruments - TPA2013D1 is a good idea. (I plan to set the bit SM_DIFF to permit this design to work).
Yes, that is helpful for minimizing noise and crosstalk.
lorenzo wrote:I will put the resistor (10R) and capacitor (47n) between GBUF and GND. Is that enough?
Yes.
lorenzo wrote:I plan also to put a resistor of 1K near the TPA2013D1 between L and R. Is a good idea to reduce the cross-talking of the digital nearby line?
I don't think that will be necessary. Note that when you set SM_DIFF, your signal is differential and that already makes you line pretty immune to crosstalk, as long as the L and R lines are adjacent to each other.

Kind regards,
- Henrik
Hi Henrik
What is the value (ohm) and Tolerance %, for the resistor CG0603MLA-5.5M (R32, R43 and R50) used in LEFT, RIGHT and GBUF out in this module? http://www.vlsi.fi/fileadmin/evaluation ... yer_07.pdf

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Panu
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Re: VS1053 low audio level

Post by Panu » Thu 2019-04-25 12:53

What is the value (ohm) and Tolerance %, for the resistor CG0603MLA-5.5M (R32, R43 and R50) used in LEFT, RIGHT and GBUF out in this module? http://www.vlsi.fi/fileadmin/evaluation ... yer_07.pdf
It is a varistor, not resistor. Please see viewtopic.php?t=2391&p=12705#p12703.
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