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Bargain eBay amp.. to good to be true?

izzzzzz6

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Feb 15, 2022
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VX Executive
Hi,
I’ve been looking for an amp to run 2 subs in my VE SS UTE and found this one on eBay for $80.
The specs seem awesome I’ll post below. Do you think it’s worth buying to try it out? Anyone have any experience with cheap amps or know anything about them?
Features:
Wudi 6800 Watt 4-Channel Car Power Amplifier
Material:Aluminium alloy
Amplifier Class: Class A/B
Model: WD628
Channel: 4
Input Voltage:DC 12V
Peak Power Output: 6800 Watts
Peak Power Output: 2 Ohms 1700 Watts x 4 Channels
Peak Bridged Power Output: 4 Ohms 3200 Watts x 2 Channels
RMS Power Output: 4 Ohms 120 Watts x 4 Channels
Power & Protection LEDs
Thermal Overload & Speaker's Short Protection
Bridgeable
Total Harmonic Distortion (THD) RMS Output: 0.01%
Signal-to-Noise Ratio (SNR): 90 dB
Minimum Speaker Impedance: 2 Ohms
Minimum Speaker Impedance in Bridged Mode: 4 Ohms

Package Include:
1 X 6800W 4 Channel Car Amplifier

Cheers


I just bought one of these (new) and I took it to pieces to check build quality etc.
The amp was badly put together causing the board to bend but I fixed that with some skills, one speaker out had a dry solder joint but I fixed that.
Some other sketchy crap but not too bad, you have to input to the front Chanel if you want to send a signal from the output, this is a shame because you can't send the low pass signal from the rear Chanel to the front channel, if this was the case you could use the low pass filter across both channels front and rear. this is an easy mod if you wanted to solder something from inside to send the bass signal to the front channel. then you could drive 2 mall subs or a sub with dual voice coil.
It is obviously not the power it states, it uses A1941 and C5198 output transistors these are rated at around 70W hifi I guess RMS each. Power dissipation at the collector 100W. I am not sure if 100W of push and 100W of pull makes 200W or if it just makes 100W of push pull.
Anyway, there are 4 transistors for the front and 4 for the rear.
At I guess I would say this amp is probably a max of 400W RMS and 800W max. Perhaps someone who better understand transistor ratings could verify this.

The amp I was more interested in was the WUDI 8808.1D this is a 2 channel amp and is supposed to be able to drive down to 1 ohm, probably 2 but has been tested briefly to 0.5 ohms. They also do a few larger versions the 8809.1 and the 8809.1D
The last two are the larger versions and might be more interesting.

These are not well made but if you are skilled you can make sure everything is well put together with no stress points etc, you can add solder to the tracks where needed etc. The main thing is to get the transistors to lie perfectly flat before you screw them down. I found that when the end plates are screwed on this messes with the position / height of the transistors over the heatsink causing stress on the legs and board if they were to be screwed down in this hovering state. I made adjustments, added a few spacers etc to take the stress off of the board, until I saw the transistors laying very close to flat against the heatsink with the end plates screwed down was I ready to screw down the clamps for the transistors.

To summarise. For the price you get a good deal, obviously the output power is a joke and you may want to do a teardown and rebuild, I also added extra thermal grease. The cheap amps are much lighter than they used to be which much feel less quality but on the other Hand who wants their car weighed down with unnecessary weight.

Another thing I noticed is that some of the parts that are prone to vibration did not have sufficient glue, such as the big caps and the power supply inductor coil but that is something else you might want to think about modding depending on how bumpy your ride is. I would not screw one of these to the side of a box, it might suffer in time from the vibrations.

I'm keen to try the 8808 or 8809 series but they are not easy to order in Europe. I see some available to Australia or you can go through an agent tp ship it from China.
 

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