It's more of an issue with electrocution than fire 😉
If the chassis is not earthed, (and it's not here) then this is a considered a Class II product. That's great for audio as it reduces the likelihood of ground loops, but if anything live shorts to the chassis, then there's nothing to prevent the chassis from going live.
Meeting Class II safety requires triple insulated wire within the chassis for anything live, and a full 6mm creepage and clearance.
The first circle shows that the earth terminal is not grounded to chassis, and the second shows the AC Line trace within 2mm of the chassis. That's both remarkably dangerous, and illegal to sell.
Luckily this could be easily fixed with two lengths of TIW run directly from the IEC inlet to the input of the power supply, bypassing the dangerous PCB traces. Twist these together tightly to reduce radiated noise. There could be other issues as well, so no guarantee this would make the product meet safety requirements.
I'm all for spending the money where it counts... on the audio portion, but being alive is a prerequisite to enjoying that good sound, so it's worth at least a small investment 😉
Regards,
Owen
Opc, I agree with your arguements. But for most people reading this tread in practice the 3e tpa3255 doesnt have any hiss on a 91db speaker (which I belive is very common). The hiss I can hear from the Aiyima 3255 is very audible and it sounds like that the highest amplitude portion of that hiss is sub 10kHz. My living room is dead silent when I turn of the AC since the house is isolated at the country side, so its probably more quiet than most rooms. I dont have any tinnitus at age 36 but I recently found out that I cant hear 15kHz sweeps which I could last year 🙁.
If one were to pair the tpa3255 up to a 100db speaker of course one might run into noise problems, but those people doesn't need 150w+ amp either.
If one were to pair the tpa3255 up to a 100db speaker of course one might run into noise problems, but those people doesn't need 150w+ amp either.
He means it's serious... and I'm being a bit silly, but it really is serious.
You're one light tap away from being electrocuted with that setup. If the internally mounted PSU shifts even 1-2mm it will contact that trace and touching your chassis (or volume control, or anything it's connected to) would be the same as jamming a fork in a wall outlet.
Please do fix it...
Regards,
Owen
You're one light tap away from being electrocuted with that setup. If the internally mounted PSU shifts even 1-2mm it will contact that trace and touching your chassis (or volume control, or anything it's connected to) would be the same as jamming a fork in a wall outlet.
Please do fix it...
Regards,
Owen
The adjuster will change voltage about +- 5%
Maybe you know why this new TPA3255 is using 4 OP amps... any idea ?
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You would of course be bypassing the front panel switch with this modification as I am sure it is switching the mains supply to the Power Supply.
The power supply has a tab for an earth connection that is not currently used and the case should also be earthed if not done through the power supply mounting bolts.
I don’t think the Chinese build these units for international safety standards. I am sure this is why we see so few units with internal power supplies.
Other comments :-
I don’t think this unit has an Anti-Pop circuit. It relies on the fact that the power supply will take time to come up to voltage and then fades away slowly when you turn it off. There doesn’t appear to be any components on the board to provide a delayed reset.
The capacitors in the signal path appear to be 1uF (not electrolytics) rather than the normal 10uF.
There are 4 Op-Amps because at least two of them will be used for the tone controls. The other two will be to provide the balanced input to the TPA3255 chip.
Two relays to switch between the Bluetooth input and the RCA Input
Thanks Kay, I was going to say much the same. There is a lot of misunderstanding of how negative feedback works !! The TPA325x chip still has the same gain so you still only require the same input voltages.
Have any of you any experience with this board?
TPA3255 4ch 2020 New DC24-48V 08
It looks just like the 4ch 3251 board from 3e Audio but using 3255... The price though... $45?
TPA3255 4ch 2020 New DC24-48V 08
It looks just like the 4ch 3251 board from 3e Audio but using 3255... The price though... $45?
I think you will find that 3e-Audio use the this chip because they already use the same chip in their preamplifier board and already developed software for it.
I think you re wrong. This is more complicated than you may think...
Just take a look at the AIYIMA TPA3255 thread... and you will understand.
I really think this amplifier has an anti pop circuit, it reacts exactly the same way as the AIYIMA TPA3251 that includes it.
Yes, a disappointing design choice - when you include a DSP inside an amplifier which only has RCA analogue inputs, the signal chain incurs two additional conversion steps - A-D,D-A.
If you want DSP it's a far better to do this before the amplifier. Then if your source is digital - which is the more common scenario - then you can go direct digital into the DSP, and if the DSP unit's D/A output stage is not great, use its digital outputs into an external D/A converter of your choice.
I would be interested in the 3e-audio All in One Amplifier if they would remove the DSP stage completely!
The BRZHIFI TPA3255 amplifier that I reviewed is a great alternative in this case )
We discussed about it in previous pages. This is a 3E Audio clone board.
Must be interesting to test it.
Could anyone tell me what sort of plug I need for the 3eAUDIO 12v aux? I’m going to try out some VU meters! Going to try a cheap kit and if it is good enough I will invest in a pair of big VU meters.