Here is a table from TI documentation:
GAIN R1 R2 INPUT IMPEDANCE
Master 20 dB 5.6 kΩ OPEN 60 kΩ
Master 26 dB 20 kΩ 100 kΩ 30 kΩ
Master 32 dB 39 kΩ 100 kΩ 15 kΩ
Master 36 dB 47 kΩ 75 kΩ 9 kΩ
Slave 20 dB 51 kΩ 51 kΩ 60 kΩ
Slave 26 dB 75 kΩ 47 kΩ 30 kΩ
Slave 32 dB 100 kΩ 39 kΩ 15 kΩ
Slave 36 dB 100 kΩ 16 kΩ 9 kΩ
But mostly it is about matching frequencies between master and slave. On some boards they set it both to master and just a little frequency difference will result in output noise.
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Somewhere on Head-Fi forum they had comparison of different op amps.
The best ones are with higher Slew Rate like AD827. I have the same experience.
Thanks for summarizing your comparisons. With these 90+% efficient Class D amps, quality power is key to getting the best from these amps. I have 20dB gain on my Wiener 2.0 TPA3116 PBTL.
Yes, my experience too. I am using a regulated linear psu for my 3116, and the sound is better.
I have read and re-read all of the posts in this thread but am still confused as to which of the ready assembled boards you guys think sound best (in stock form).
I am not a modder (poor eyesight and rubbish soldering skills) so I just want something I can stick in an enclosure add some connections and off we go.
The choice seems to be these two
TPA3255 2x260 Watt Class D Audio Amplifier | eBay
TPA3255 Digital Power Amplifier Class D Audio Amp Assembled Board 300W+300W HiFi | eBay
one is considerably cheaper than the other (good for me) but does the "you get what you pay for" maxim apply here?
Any advice welcomed
I am not a modder (poor eyesight and rubbish soldering skills) so I just want something I can stick in an enclosure add some connections and off we go.
The choice seems to be these two
TPA3255 2x260 Watt Class D Audio Amplifier | eBay
TPA3255 Digital Power Amplifier Class D Audio Amp Assembled Board 300W+300W HiFi | eBay
one is considerably cheaper than the other (good for me) but does the "you get what you pay for" maxim apply here?
Any advice welcomed
one is considerably cheaper than the other (good for me) but does the "you get what you pay for" maxim apply here?
Any advice welcomed[/QUOTE]
I have both boards and it all depends on what you are looking for...
Wiil it replace a mediocre amp, both amps are fine and will give you some good sound...
If it has to replace a top class musical amp...I would not go this way and keep that amp...
If you just want to check what class d amps can do today (that is why I bought a few) and like to experiment a bit...this is big fun...sometimes I am surprised how good these cheap amps can sound...but I have to be honest, this is not the ultimate amp I am looking for...(but as a tubeman I might be a little biased)
I would give the 3e-audio a plus because of the quality...@100 dollar
But the yj board is less than half that price and works/sound very similar...
If it is an experiment you are looking for, go for the cheapest...if class d and tpa3255 is good sounding for you in your system you could consider upgrading later...there will be other boards with tpa3255 the coming months...I think.
Any advice welcomed[/QUOTE]
I have both boards and it all depends on what you are looking for...
Wiil it replace a mediocre amp, both amps are fine and will give you some good sound...
If it has to replace a top class musical amp...I would not go this way and keep that amp...
If you just want to check what class d amps can do today (that is why I bought a few) and like to experiment a bit...this is big fun...sometimes I am surprised how good these cheap amps can sound...but I have to be honest, this is not the ultimate amp I am looking for...(but as a tubeman I might be a little biased)
I would give the 3e-audio a plus because of the quality...@100 dollar
But the yj board is less than half that price and works/sound very similar...
If it is an experiment you are looking for, go for the cheapest...if class d and tpa3255 is good sounding for you in your system you could consider upgrading later...there will be other boards with tpa3255 the coming months...I think.
Thanks for the info diytoon...
I have and use regularly; gain clones, TPA3116 and TA2020 amps, I am looking for something with more power and perhaps a better grip of my Proac Response 2.5s.
I read somewhere that somebody had compared the TPA3225 to NCore modules and the results were pretty close. I have had fist hand experience with the NCores in both the stereo and monoblock versions of the Nord One SE which uses the Hypex NCore NC500 modules, if I could get somwhere close to that sound I would be pretty happy.
I have and use regularly; gain clones, TPA3116 and TA2020 amps, I am looking for something with more power and perhaps a better grip of my Proac Response 2.5s.
I read somewhere that somebody had compared the TPA3225 to NCore modules and the results were pretty close. I have had fist hand experience with the NCores in both the stereo and monoblock versions of the Nord One SE which uses the Hypex NCore NC500 modules, if I could get somwhere close to that sound I would be pretty happy.
I would suggest to try the cheapest one and see if that is working for you...
You would have a little more power than the 3116 stereo...or try a 3116 mono...
Class D Amps are quite inexpensive, he could try the best one. With a cheap one, he might get a wrong impression about 3255.
1. there is a very loud 'POP' noise when power supply drop during playing music through my phone, now i need to stop my music first before pull out the power supply......
2. the display LED always ON,i check the datasheet that it's' for clipping and fault indicate,now i don't know when it will clip or fault since it always working.(i did ask the seller but he said it's normal)
3. there is one IC not mounted,but the picture show on the selling page,it does has.(i did ask the seller but he said it's normal
1. At what voltage you're running this board? If they used the mute circuit from the EVM their might be effects like this if capacitor values aren't like noted due to DC-bias. I tried this circuit as well, it isn't the best solution. (I use an improved one with my boards)
2. + 3. The missing 3.3V regulator isn't usually an issue as this is only used for the logic levels and indicators. I don't know their schematic but this might come from missing part. The 3251EVM where done without if i remember correctly, the LEDs where connected to 12V.
Hi,
1,i running from a 48V DC,do you have a solution to share here?can easy to make it happen on this board?by hand made i mean....
2,even they missing this part,but the problem is that in some case you never know when it will clipping though it doesn't impact use,all LED turn on mean something worse happen on my experience....like the traffic light on the road....
1,i running from a 48V DC,do you have a solution to share here?can easy to make it happen on this board?by hand made i mean....
2,even they missing this part,but the problem is that in some case you never know when it will clipping though it doesn't impact use,all LED turn on mean something worse happen on my experience....like the traffic light on the road....
Someone can post pictures in good quality from top/bottom side with heatsink removed?
The problem with the status indicators is from the missing the 3.3V regulator as the gate of the LED FETs aren't pulled up correctly. This normally isn't needed as long as you use FETs with logic level or really low Vgs_th like BSS138. I'd guess, the actuall stuffed FETs aren't the right ones. The TPA32XX does have weak internal pullups, so ext. pullups are needed with the correct FETs.
Someone can tell the marking code of those? They're near the leds and resistors marked 47k / 100R
Beside this, someone can measure the voltages at the AMS1117 footprint referered to GND? There should be equal/less than 15V on Pad 3 (right pad when rotated so that the heat slug pad is on top)
http://www.advanced-monolithic.com/pdf/ds1117.pdf
One way to fix:
- stuff an 1117-3.3
- stuff BSS138 in place of the actual FETs
Fixing pop, like so:
Zener is important to protect the IC from transients.
The problem with the status indicators is from the missing the 3.3V regulator as the gate of the LED FETs aren't pulled up correctly. This normally isn't needed as long as you use FETs with logic level or really low Vgs_th like BSS138. I'd guess, the actuall stuffed FETs aren't the right ones. The TPA32XX does have weak internal pullups, so ext. pullups are needed with the correct FETs.
Someone can tell the marking code of those? They're near the leds and resistors marked 47k / 100R
Beside this, someone can measure the voltages at the AMS1117 footprint referered to GND? There should be equal/less than 15V on Pad 3 (right pad when rotated so that the heat slug pad is on top)
http://www.advanced-monolithic.com/pdf/ds1117.pdf
One way to fix:
- stuff an 1117-3.3
- stuff BSS138 in place of the actual FETs
Fixing pop, like so:
Zener is important to protect the IC from transients.
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I have no personal experience about any of the boards yet, but based on some of the posts regarding opinions, it may be that the weak point of the non-TI boards are that they do not utilize the NE5532 to feed the signal to the TPA3255. It seems the TPA3255 can be somewhat sensitive in terms of pre amp stage.
Do not know if there is any truth to my assumption, but it is not unlikely, and it is also mentioned in the users manual of the TI EVM board that the TPA3255 benefits from a good pre stage such as for instance NE5532.
Do not know if there is any truth to my assumption, but it is not unlikely, and it is also mentioned in the users manual of the TI EVM board that the TPA3255 benefits from a good pre stage such as for instance NE5532.
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