Hi, new member here. I'm finally starting some diy project so here I am, having some troubles already 
Anyway, I want to make a bluetooth speaker so I purchased this TDA7492P bluetooth amp from ebay.
It's not bad for 10 bucks. The only thing that concerns me is popping when turning on, actually it's not popping as much as it is pushing the cones outwords for at least half a second and it doesn't look safe, so i'm thinking if there is a way to connect something on output before speakers to limit this sudden flow of power. The last thing I would like to put is volume because I would have to turn it down every time I'm turning on the speakers...
Anyway, I want to make a bluetooth speaker so I purchased this TDA7492P bluetooth amp from ebay.
It's not bad for 10 bucks. The only thing that concerns me is popping when turning on, actually it's not popping as much as it is pushing the cones outwords for at least half a second and it doesn't look safe, so i'm thinking if there is a way to connect something on output before speakers to limit this sudden flow of power. The last thing I would like to put is volume because I would have to turn it down every time I'm turning on the speakers...
Well, the BT module should take care on this by utilizing one of its PIOs to drive the Mute of the amp.
From the DS here:
http://www2.st.com/content/ccc/reso...df/jcr:content/translations/en.CD00211320.pdf
Page 18/27 Figure 21
A "crude" softstart or longer startup mute time can be accomplished by changing R4 to a high value of i.e. 810k for the case, they implemented it like that. If not (would guess) it needs to implemented from scratch. 3v3 should be avail at the BT module. (Mute Pin is 3v6 max)
From the DS here:
http://www2.st.com/content/ccc/reso...df/jcr:content/translations/en.CD00211320.pdf
Page 18/27 Figure 21
A "crude" softstart or longer startup mute time can be accomplished by changing R4 to a high value of i.e. 810k for the case, they implemented it like that. If not (would guess) it needs to implemented from scratch. 3v3 should be avail at the BT module. (Mute Pin is 3v6 max)
Here's the pics with and without bckg light:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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Hi Doctormord,
thanks a lot for your advice to change the resistor. I even had an older version of the bluetooth TDA7492P module with two 39 kOhm resistors. After replacing R21 by an 1 MOhm version the evil popping noises are gone now.
Wish you a nice weekend,
Thomas
Many thanks all of you for posting this information and the follow up confirmation. I had written this amp off because of this problem but will now see about changing out R21 and give it another try. For those who don't want to fool with changing SMD resistors, the similar Sanwu TPA3116 bluetooth board that xrk971 recommends in this thread does not exhibit the problem.
http://www.diyaudio.com/forums/class-d/275961-30-tpa3116-bluetooth-speaker-protection-eq-any-good.html
Doctormord, would you be willing to create instructions for us plain folks on how to reprogram the bluetooth module to eliminate or reduce the beeping sounds? I am using the TPA3116 version at the moment but I assume the process is the same for most of the CSR chips? If we could also rename the device that would be icing on the cake.
I'm curious if anyone has compared the Sanwu TPA3116 BT amp to the Sanwu TDA7492P BT amp with respect to sound quality.
http://www.diyaudio.com/forums/class-d/275961-30-tpa3116-bluetooth-speaker-protection-eq-any-good.html
Doctormord, would you be willing to create instructions for us plain folks on how to reprogram the bluetooth module to eliminate or reduce the beeping sounds? I am using the TPA3116 version at the moment but I assume the process is the same for most of the CSR chips? If we could also rename the device that would be icing on the cake.
I'm curious if anyone has compared the Sanwu TPA3116 BT amp to the Sanwu TDA7492P BT amp with respect to sound quality.
I compared both boards and actually would only recommend the TPA3116 version, board revision 2.2 and up.
Reprogramming the CSR modules needs an SPI programmer and some CSR tools, but will check if its possible to reprogramm the EEProm with a simple I2S programmer, which are avail from China for cheap (CH341 based).
Reprogramming the CSR modules needs an SPI programmer and some CSR tools, but will check if its possible to reprogramm the EEProm with a simple I2S programmer, which are avail from China for cheap (CH341 based).
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