This is the type of red board I have, bought around 2 years ago with cooling paste. One day I actually wanted to find out why it suddenly stopped but then it worked well for some hours ahead. It is impossible to find errors in a circuit when it works. Another approach is to draw-up the circuit schematic and analyze it but for that board it is not a trivial job. In general for Asian boards (amplifiers, DACs and power supplies), I have seen quite a number of flaws in the construction of power supply arrangements and ratings of components. That resulted in wrong operational conditions stated for supply voltage. It may be that the designer did right and it was the production that following wanted to save some costs. When I one day have had time to draw-up the schematic, I will let you all know what are my findings. Until then also I work in the haze and can only propose you to check the most trivial parameters.
In principle, when you get a new board from Asia, you should first check it with “gentle” operating conditions such as a supply voltage a bit above minimum and 8 Ohm speakers. Then you should draw up the circuit, analyze it and conclude what maximum operational conditions that should be used. I know it does not work like that in practice.
In principle, when you get a new board from Asia, you should first check it with “gentle” operating conditions such as a supply voltage a bit above minimum and 8 Ohm speakers. Then you should draw up the circuit, analyze it and conclude what maximum operational conditions that should be used. I know it does not work like that in practice.
Dear Faux, thank you, I have learned my lesson and will be more methodical from now on.
For now my working diagnosis is a dead chip due to no thermal paste if my 3rd old board will continue to work in the same setup.
How should I attach the speakers though? Do you know about the BTL mode? Should I use that? Or simply connect speakers in series even though then one channel has nothing and one 5 Ohm with the 2 speakers?
Cheers,
Ulf
For now my working diagnosis is a dead chip due to no thermal paste if my 3rd old board will continue to work in the same setup.
How should I attach the speakers though? Do you know about the BTL mode? Should I use that? Or simply connect speakers in series even though then one channel has nothing and one 5 Ohm with the 2 speakers?
Cheers,
Ulf
Hi Ulf,
You have two 2.5 Ohm speakers (probably for a car) and a stereo amplifier board that should not run with less than 4 Ohm on each channel to be safe.
Most likely you have a stereo input signal in which case I would use the (not elegant) configuration with a 2.2 Ohm power resistor in series with each speaker and one speaker on each output. If your signal is mono, you could in theory use what we call PBTL-coupling. But, as you have already lost two amplifier boards, changing for PBTL-coupling could go wrong and I would use the same as for stereo.
FF
You have two 2.5 Ohm speakers (probably for a car) and a stereo amplifier board that should not run with less than 4 Ohm on each channel to be safe.
Most likely you have a stereo input signal in which case I would use the (not elegant) configuration with a 2.2 Ohm power resistor in series with each speaker and one speaker on each output. If your signal is mono, you could in theory use what we call PBTL-coupling. But, as you have already lost two amplifier boards, changing for PBTL-coupling could go wrong and I would use the same as for stereo.
FF
I bought the Fosi TDA949e amp from Amazon. It came with a 24v, 4.5A laptop style charger, which works out to 108W theoretical power output. I have an old Dell charger which is 19.5v, 9.23 which is 180W (i.e.72W more). Is the Dell charger going to be a better option if I need to upgrade? The main question is do we need to go with higher voltage or higher amperage or is it the total power that matters?
If you want to use low impedance speakers (2-3 Ohm), the Dell PS is the better choice, on high impedance (10-32 Ohm) the included one gives more headroom. Granted both deliver clean power without switching noise, high ripple etc and don't fold back quickly. To use the higher power is not always possible even if the specifications promise more, a fold back (temporary shut off, drop off of the voltage) can happen at short impulses while the average power is still far below the specs.
The JBL Stage A130 reach max excursion way below the power both can deliver and they got just a 25mm VC in the woofer, so it can't take more than 50W anyway.
Exactly! Use the one with the lowest noise.
YW 
It is often that way, a good power supply which does not sag much in voltage often keeps the bass a lot more precise and 'darker', with more authority. The feedback does its part to compensate for a certain voltage drop but the difference is often clearly audible. If you want to use really demanding speakers with low impedance, remove the power supply plug and solder the cable directly on to the board if it doesn't already have screw joints. One of these guys got a lot lower contact resistance than the small surface of the coaxial power connector.
It is often that way, a good power supply which does not sag much in voltage often keeps the bass a lot more precise and 'darker', with more authority. The feedback does its part to compensate for a certain voltage drop but the difference is often clearly audible. If you want to use really demanding speakers with low impedance, remove the power supply plug and solder the cable directly on to the board if it doesn't already have screw joints. One of these guys got a lot lower contact resistance than the small surface of the coaxial power connector.
