LM3886 Review of eBay amplifier with thermal, performance and distortion. Used in Gainlclone.
Вставка
- Опубліковано 8 тра 2021
- A review of a LM3886 eBay amplifier is performed. Performance, efficiency, thermal, heatsink, design issues and possible modifications are discussed.
- Наука та технологія
Great analysis. I have built several 3886 based amps recently, seriously heatsinked kit products, they work very well.
Good to hear. The LM3886 does a decent job but they do need a decent sized heatsink.
Hi Don. I know you was laughing about adding those 2 extra heatsinks but that is exactly what is needed. Almost all the amplifiers from Ali/EBay etc are almost always under heatsinked. It is done like that to make it cheaper. The money in any amplifier is in the power transformer and good heatsinking. This amplifier suffers from both these limitations. If these things were addressed, it would cost double, and no one would buy it. You can get a similar module with fan cooling but it's quite noisy as the fans run flat out. Again a mod you can do it to wire the 2 fans in series, makes it quite a good little amplifier and fan noise is fine. Most of all it runs almost cold and stops the amp running into thermal limiting.
I agree. Most of the amps I have worked with, the chassis, heatsink and power supply are a majority of the cost.
How many amperes is a good transformer for an LM3886 stereo amplifier?
For a robust design, I think you want the secondary windings to be rated for 6 amps (for a stereo design).
@@DanPattenAudioG33k in my country the average person sells 5A or 10A... 6A ones are rare.. Can a 5A transformer be used for this amplifire?
But these IC 3886 are original or fake?
Hard to say. The performance seemed ok, so there were no red flags about being fake.
The ac fuse might be in the socket
That is a good thought. If I recall, I checked for that but might have missed it.
There must be something wrong with the circuit used or parts used.
Are you referring to the thermal issues? The LM3886 has a quiescent current of 0.050A to 0.085A. I have typically measured the device at 0.065A. 0.065A x 72V x 2 (stereo) = ~10W of power dissipation. This is just the two LM3886 while at idle. 10W is a fair amount of power to get rid of.
@@DanPattenAudioG33k I have built a number of LM 3886 power amplifiers, using a plus, minus 35 vdc power supply, and they work well. The IC does run hot when driven hard. The heat sink should be large. When driving just one watt of power, a little warm is all it should get, unless your driving a load of four ohms or less, then I don't know. The transformers I have used deliver plus minus 4 amps per side, and when driven into a 8 ohm load there was no loading down of the power supply voltages, how ever there was with a 4 ohm load the IC got hotter quicker and the PS voltage drop. To my way of thinking, the IC does not mind high voltages (within its limits), but it gets hot over delivering high current. From your video it sounds like the IC is using too much current for the load driven, and or the transformer is to weak, or maybe there is something else.
Thanks for sharing. I guess one of the points I was trying to make in the video is that the LM3886 can dissipate a fair amount of heat. A typical problem with implementing this IC is not using a large enough heatsink. Always seems to take a larger heatsink than anticipated. Thanks.
That transformer is a joke for two LM3886
I ran the amplifier to full power and did not recall seeing any droop in the voltage rails (which would indicate undersized transformer). FYI.