Well, we are talking about tinkering/diying a 2 $ amp, sub standard engineering design? Seriously?
I do not quite understand your "decoupling cap in the range of hundreds of uF" comments. If you look at the schematic (fig. 27) on p14 in the data sheet, I did not see any "decoupling cap in the range of hundreds of uF". I only saw a 220uf cap connected to the PVCC (for power filtering I presume).
You are right. I did not try hard enough. Look like almost all of them are from one manufacturer. They are all mono amps and look like a Sanwu clone. But for tinkering, I guess mono is OK. However, along the line voltwide and you alluded to already, and my own experience with these amp boards, I definitely will not touch these amps. If the bare chips (assuming they are not fake) costs 6-7 RMB, a 9 RMB board is just way over the line in terms of price. Would you buy them? I am cheap, but I do know the bottom line and not unrealistic.
Point being, those blue Sanwu-clone boards are (still) better-designed than those (nearly) cap-less, filterless abortions.
If you had bothered to read through that Wikipedia page, and my first post you quoted / replied to, you might've begun to figure out that "decoupling" might mean "power filtering". "Decoupling" is NOT the same thing as "coupling capacitor (for signals)", by the way. And i know my math is far from perfect, but 220 is quite firmly in the "hundreds"-range. It goes one hundred, two hundred, three hundred etc, doesn't it?
The bare chips are 6-7RMB a piece - "obviously" you can get an even better deal in bulk. Sometimes economies of scale can be kinda nice...
I have two 3118 from Sanwu and four 3116 from different vendors. One of the 3116 sounded really bad, the other mediocre, two of them quite good. The 3118 sounded fine. Not sure I can tell whether the chip is fake. Unless one cut open the chip, it would be difficult to tell. I thought Doctormod did that sometime ago on one suspected item and turned out to be false alarm.
Regards,
Thanks for your answer, it is very subjective, but i trust you.
I've dismantled some of them and there were components values errors.
But all the blue 3118 cards that i have sound fine and the measurements are good.
I've performed extended tests with dummy loads and they perform really well especially about the energy efficency.
I know I'm late to the game on these with all the fuss about the TPA32XXs, but here are some comments on these little blue boards. First, as many have found out (as I did a few minutes after power up), if you run these without speakers (or load) connected, you risk releasing the magic smoke. The damaged component may very well be C18 or C34 (see picture). C18 on mine was visibly damaged. This capacitor is 1uF. Note TI datasheet has it as 680nF. Yageo 1uF X7R (Digikey P/N 311-1456) would be a suitable replacement if you enjoy wasting time attempting to repair these throw away boards. I can't help myself. Kind of a pain, but not impossible. Get a few extra, they are a measly 11 cents.
The hiss at the stock gain of 36 is plainly unacceptable. I can’t believe billions of these boards were made with the gain at 36. Why? I cannot say. Perhaps alcohol played a role. I removed R27 for a gain of 20 and now the boards are dead quiet, even at maximum volume. Very good sounding, though a bit of a pain to set up and run due to lack of terminal blocks and dealing with the mono nature of these boards. I guess very nifty if you need to have control over the number of channels. Not quite sure they are worth it if you are dealing with a two channel situation, with so many good sounding two channel solutions out there that are practically plug and play. Anyway, another easy Class D project with minimal fund expenditure (due to lax import duties?). Can’t complain.
The hiss at the stock gain of 36 is plainly unacceptable. I can’t believe billions of these boards were made with the gain at 36. Why? I cannot say. Perhaps alcohol played a role. I removed R27 for a gain of 20 and now the boards are dead quiet, even at maximum volume. Very good sounding, though a bit of a pain to set up and run due to lack of terminal blocks and dealing with the mono nature of these boards. I guess very nifty if you need to have control over the number of channels. Not quite sure they are worth it if you are dealing with a two channel situation, with so many good sounding two channel solutions out there that are practically plug and play. Anyway, another easy Class D project with minimal fund expenditure (due to lax import duties?). Can’t complain.
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I have more of these "little blue boards" and I use them with the initial gain. An hour ago I put my ear to the speaker, with the board turned ON (19V supply) but without input signal, and I hear no hiss. I know that the TPA3116/TPA3118 generate hiss if they look into a high impedance at the input. I drive the boards from a high quality headphone amplifier (low output impedance).
But, you are right - why configure them for more gain than you need?
But, you are right - why configure them for more gain than you need?
Are these legit Sanwu boards on Amazon?
KNACRO TPA3118 BTL 60W Mono Digital Audio Power Amplifier Board Module DC 12V-24V
or
KKmoon TPA3118 PBTL Mono Digital Amplifier Board Module 1*60W Power AMP DC 8-24V
Anyone know if these are legit Sanwu boards? I much rather prefer Amazon & stay as far away from ebay, even if it means a few extra doll hairs. Thanks!
KNACRO TPA3118 BTL 60W Mono Digital Audio Power Amplifier Board Module DC 12V-24V
or
KKmoon TPA3118 PBTL Mono Digital Amplifier Board Module 1*60W Power AMP DC 8-24V
Anyone know if these are legit Sanwu boards? I much rather prefer Amazon & stay as far away from ebay, even if it means a few extra doll hairs. Thanks!
It doesn't say Sanwu in the adverts. The pictures imply it. It's a risk. Either spend little but risk copies or maybe mosey on over to Sanwu Lasers and look at the TPA3110 mono board.
I got the same board with the same parts, except the lower left dot on the 3118 is not printed. Mine is molded. It works as it should be.
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Guys, go to Aliexpress and buy dozenz if you want, they're sold for 1.6 USD each. All of them are the same, isn't it obvios?
Question: Does anyone (knows if there are) which are the input capacitors on the small blue boards?
I've searched the thread and nobody is talking about them and we know how important they are. Also changing the gain changes the input impedance of the amps which is further related to those input capacitors. Though decreasing the gain, the input impedance increases meaning there is no need for bigger input caps...
I've searched the thread and nobody is talking about them and we know how important they are. Also changing the gain changes the input impedance of the amps which is further related to those input capacitors. Though decreasing the gain, the input impedance increases meaning there is no need for bigger input caps...
I'll try harder, because I really can't spot the traces
(You're so mean.)Seems these are the ones? Am I seeing right?
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http://sorbits.dk/classd/IMG_20160806_173342.jpg
C4<something> seems to go from the input pad to pin 4, and C2<something> seems to go from pin 5 to ground.
PBTL is the lower half of the schematic on page 20 of the datasheet
http://www.ti.com/lit/ds/symlink/tpa3116d2-q1.pdf
Mean? Just because you were too lazy(?) to do a google image search (hint: Tools -> Size -> Large)?
C4<something> seems to go from the input pad to pin 4, and C2<something> seems to go from pin 5 to ground.
PBTL is the lower half of the schematic on page 20 of the datasheet
http://www.ti.com/lit/ds/symlink/tpa3116d2-q1.pdf
Mean? Just because you were too lazy(?) to do a google image search (hint: Tools -> Size -> Large)?
Don't take it seriously, you have you point. As I said, the traces were hard to spot for me even in those high res photos. Thank youhttp://sorbits.dk/classd/IMG_20160806_173342.jpg
C4<something> seems to go from the input pad to pin 4, and C2<something> seems to go from pin 5 to ground.
PBTL is the lower half of the schematic on page 20 of the datasheet
http://www.ti.com/lit/ds/symlink/tpa3116d2-q1.pdf
Mean? Just because you were too lazy(?) to do a google image search (hint: Tools -> Size -> Large)?
Anyway, I've been thinking and I'll go with another boards
(ex: STA508 CLASS D AMP Kit 80W+80W on Aliexpress).
They're better build and easier to modd.
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