Fasten seat belts. TDA8932 pessimistic review.

[abraxalito]

Gain reduction is best accomplished through the turns ratio of the input transformer, something I've done on numerous TDA8932BT boards to good effect. Generally I prefer to have an amp with a 1VRMS input sensitivity for full output, on a 35V supply this means a turns reduction of 2.6:1. One upside of using the transformer is the input impedance goes up and the output impedance comes down, compared to a resistive attenuator.

 

[ICG]

That does not really reduce the noise of the very high gain, you can acieve the same by just using a voltage divider or a potentiometer. The mentioned change in the circuit changes the input OP though, so that's a complete different story.

 

[abraxalito]

I have not noticed noise caused by having very high gain (63.1X). Has anyone else noticed that?

From the DS the typical output noise in the audio band is 100uV, corresponding to SNR of over 107dB with zero source resistance at 35V supply. The resistive attenuator will add noise though.

 

[ICG]

Maybe I confused something, not sure anymore.

 

[nastorrent]

Hi,

I've been reading the post and now I'm confused about the different board versions.
Can anyone suggest me the recommended board version. Thanks in advance.

 

[saposoft]

I dunno if someone else tried to test the thing (I mean REAL test like in Lab test) but I just did it and trust me you don't want to know the results...
Test parmeters
Pwr supply 20V , Bench linear regulated pwr supply
Load 8 Ohm non inductive
Output power 1W
below 1KHz THD 0.2% above rise up to 5% at 20 KHz

Does it sounds good ?
NOPE ! but it sounds enough for a quick 'n' dirty amplified loudspeakers couple i'm putting together to listen music in the garden... hope ...

 

[Jerms]

Hi,

I've been reading the post and now I'm confused about the different board versions.
Can anyone suggest me the recommended board version. Thanks in advance.

The ones from the 1st post....
You would need to know someone who knew they got a "good" board recently, then order from the same vendor.
All those eBay adverts seem to "borrow" images from elsewhere. You have to take a chance and buy, then see what turns up.

 

[yakelkun]

Hello,
I salvaged 8+1 speakers from a soundbar+Bass case and I'd like to reuse part or all of them in a compact boombox.

I purchased some low priced Amp D board, but I was quite dispointed with the 'hiss' and other noises.

I was wondering if these ultra low priced board :

https://www.aliexpress.com/item/Free-shipping-Digital-power-amplifier-board-module-35w-mono-amplifier-module-High-power-TDA8932-low-power/32731894828.html?spm=2114.01010208.3.3.qOPHDU&ws_ab_test=searchweb0_0,searchweb201602_1_10065_10068_433_434_10136_10137_10138_10060_10062_10141_10056_10140_10055_10054_128_301_10059_10531_10099_10530_10103_10102_10096_10052_10053_10050_10107_10142_10051_10106_10143_10526_10529_10084_10083_10119_10080_10082_10081_10110_10111_10112_10113_10114_10037_10078_10079_10077_10073_10070_10122_10123_10120_10124-128_10120,searchweb201603_3,afswitch_1_afChannel,ppcSwitch_4,single_sort_0_default&btsid=5a29a38c-3dff-44fa-849c-7696244c678c&algo_expid=873d78ea-0ad5-4fcc-8519-d2e097f21441-0&algo_pvid=873d78ea-0ad5-4fcc-8519-d2e097f21441#feedback

https://www.aliexpress.com/item/Free-shipping-Digital-power-amplifier-board-module-35w-mono-amplifier-module-High-power-TDA8932-low-power/32731894828.html?spm=2114.01010208.3.3.qOPHDU&ws_ab_test=searchweb0_0,searchweb201602_1_10065_10068_433_434_10136_10137_10138_10060_10062_10141_10056_10140_10055_10054_128_301_10059_10531_10099_10530_10103_10102_10096_10052_10053_10050_10107_10142_10051_10106_10143_10526_10529_10084_10083_10119_10080_10082_10081_10110_10111_10112_10113_10114_10037_10078_10079_10077_10073_10070_10122_10123_10120_10124-128_10120,searchweb201603_3,afswitch_1_afChannel,ppcSwitch_4,single_sort_0_default&btsid=5a29a38c-3dff-44fa-849c-7696244c678c&algo_expid=873d78ea-0ad5-4fcc-8519-d2e097f21441-0&algo_pvid=873d78ea-0ad5-4fcc-8519-d2e097f21441#feedback

should do the trick.

My idea is to reuse the big bass case who also hosted the electronic (out of order), and put it at least x2 speakers maybe more.

x1 Sub
x2 Low range
x4 Mid range
x2 Tweeter

I'll use a car mp3+Bluetooth board like
https://www.aliexpress.com/item/12V-Lyric-Show-LCD-Display-Bluetooth-MP3-Decoding-Board-Module-SD-MMC-USB-FM-Remote-Folder/32619540565.html?spm=2114.10010108.1000014.6.UTyIWq&scm=1007.13338.78123.000000000000000&pvid=9d500673-94ed-4e66-89fb-4fe95a3802cc&tpp=1
or
https://www.aliexpress.com/item/Smart-Black-Remote-MP3-Player-ZTV-M011-Remote-Controller-Module-FM-USB-2-0-3-5mm/32628738024.html?spm=2114.13010308.0.0.OxDI9d

To power the tiny amp boards.

Of course some crossover and inner casing will be used to optimize the sound quality.

My questions :

- Are these little Amp board 'Hiss' free ?
- The caps are changing with every seller, I know there will be some quality variations, but is there some caps to avoid, some to look for ?
- Can you provide a link to show SE connexion, as every board image I found only show BTL soldering points.

 

[yakelkun]

The second board link is wrong, the good one :

https://www.aliexpress.com/item/1pcs-TPA3118-PBTL-mono-digital-amplifier-board-1X60W-12V-24V-POWER-AMP/32693814915.html?spm=2114.13010208.99999999.269.1jnFlJ

 

[nastorrent]

I have one similar to this (some minor changes) https://www.aliexpress.com/item/1pcs...999.269.1jnFlJ
Sound good but it's configured with too much gain (Thirty some dB).
I've read on some post that sound very good configured to 20 or 26dB gain. It's a minor change of 2 resistor values (on my board R27 and R28), but they are small SMD .
If you find one configured by default with 20 or 26dB, please post the link

 

[Buehgemeiste]

I wrecked a TDA8932BT during an upgrade of a boombox (removing the applied connector sockets was a bad idea...)
I replaced it with a TDA8932T and i must say that i cannot hear a difference in sound quality.

 

[yakelkun]

@nastorrent, thanks for your feedback, can you post the resistor mod link please ?

 

[danielwritesbac]

I have one similar to this (some minor changes) https://www.aliexpress.com/item/1pcs...999.269.1jnFlJ
Sound good but it's configured with too much gain (Thirty some dB).
I've read on some post that sound very good configured to 20 or 26dB gain. It's a minor change of 2 resistor values (on my board R27 and R28), but they are small SMD .
If you find one configured by default with 20 or 26dB, please post the link

Optimizing the bridge amp isn't quite so easy. Any direct connection between one amp input and another needs a resistor installed series. The notion of base stopper resistor seems to have been forgotten for Class D amplifiers. That initial portion of the circuit isn't Class D. Actually, the small signal input is identical to amplifiers of the past and the new technologies didn't need to be crippled by omissions to spare the cost of a resistor.

 

[yakelkun]

Indeed, the mod seems quite complicated (Thanks @nastorrent )...

 

[danielwritesbac]

Indeed, the mod seems quite complicated (Thanks @nastorrent )...

It doesn't actually get easier.
This thread has within it, the easiest ways that I have ever seen to get either relevant mid-fi or hi-fi and at the lowest cost.

We do possibly, have the need of a new board design to make the optimal usage easier. So far, that ease has not been forthcoming. Had that been provided, it would be quite the shock and entirely unique.

 

[danielwritesbac]

My newest active speaker is using two of the TDA8932BT amplifiers (in SE mode, with wee little caps series to power ground for speaker return) to drive electrostatic tweeters.

In that usage, it can do what I wanted to hear, considerably better than its peers. It sure does seem less complicated than what you'd have to do to beat it.

 

[yakelkun]

seems very interesting to me, can you give a link to these "TDA8932BT" board and mod please ?

Also what power supply do you use, as it impacts a lot on HF noise ?

 

[danielwritesbac]

seems very interesting to me, can you give a link to these "TDA8932BT" board and mod please ?

I put 4u7 series between tweeter - and amplifier power ground. Those caps were Nichicon ES 4.7uF 50v capacitors. More complexity was unnecessary for a tweeter-only amplifier.
But, if you wanted some, see the datasheet.

Also what power supply do you use, as it impacts a lot on HF noise ?

The power noise immunity was surprisingly high. I don't normally claim that. However, in this case, so long as it was DC within a passable voltage range, then it works just fine.

It was not responsive to my published DC side filters, because it had no need of them. It was actually not responsive to any filter I threw at it because the need was not present.

If it had been used in stereo, with just one supply, then there is some opportunity for individualized, per channel, filtering to work; because, it would eliminate crosstalk. Otherwise, I couldn't possibly manage to embellish the power circuit.

 

[danielwritesbac]

I scrolled back. . . On the 8th of Janurary, 2016, I found out what this amp can do.

It took half a year to find out what this amp can do. And then a year after that, the usage could be relevant. . .

I set TDA8932BT against its peers and come up with wondering where are its peers?

After a year, what I'd like to know is if it has peers.

 

[abraxalito]

I've been looking around for a while and haven't noticed anything else that touches it.