Firebottle
04-03-2019, 09:44
I was asked for a recommendation for a headphone amplifier but I don't have much experience of these.
I took a quick look on fleabay and this came up as the cheapest on there, so I though I would give it a punt and see what's what.
https://www.ebay.co.uk/itm/Mini-HIFI-Stereo-Audio-Headphone-Power-Amplifier-Portable-3-5mm-Digital-Amp/113181827888?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
This was from a UK stock, from China you can get it 35p cheaper :eek:
The amplifier uses an LP-2020A integrated circuit, this is a class D chip feeding the rear speaker outputs but interestingly there are separate analogue outputs to the front headphone socket.
It's a tiny little thing
http://i66.tinypic.com/ifuag8.jpg
As usual the power LED is rather overdriven, given that modern LEDs are super efficient, the current was about 8mA providing a blinding light.
http://i64.tinypic.com/11loqz8.jpg
With a quick swap out of the LED series resistor from 1.5K to 56K the light level was substantially reduced.
http://i65.tinypic.com/2cia3jc.jpg
Given the small size you only get a 3.5mm input socket and a block connector for the speakers.
http://i64.tinypic.com/2qvv2o5.jpg
The class D power amp switches at 480KHz, the standing supply current is 48mA (8mA to the LED) rising to less than 200mA for a very good domestic volume. The instruction specify a 2A supply but imo that isn't needed.
When the headphones are plugged in the switching power amp is cut off, which is a good thing and the standing current drops to 15mA (7mA with LED mod) so very suitable for battery operation as a headphone amplifier.
http://i68.tinypic.com/11b830k.jpg
The headphone output certainly goes loud and stays clean. All my headphones are 64 ohms impedance so I can't comment on how well it would drive high impedance phones.
Cheap as chips and excellent performance, apart from the blinding LED :rolleyes:
Postscript. Just tried it at 9V supply and it works no problem. It doesn't work at 5V supply.
I took a quick look on fleabay and this came up as the cheapest on there, so I though I would give it a punt and see what's what.
https://www.ebay.co.uk/itm/Mini-HIFI-Stereo-Audio-Headphone-Power-Amplifier-Portable-3-5mm-Digital-Amp/113181827888?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
This was from a UK stock, from China you can get it 35p cheaper :eek:
The amplifier uses an LP-2020A integrated circuit, this is a class D chip feeding the rear speaker outputs but interestingly there are separate analogue outputs to the front headphone socket.
It's a tiny little thing
http://i66.tinypic.com/ifuag8.jpg
As usual the power LED is rather overdriven, given that modern LEDs are super efficient, the current was about 8mA providing a blinding light.
http://i64.tinypic.com/11loqz8.jpg
With a quick swap out of the LED series resistor from 1.5K to 56K the light level was substantially reduced.
http://i65.tinypic.com/2cia3jc.jpg
Given the small size you only get a 3.5mm input socket and a block connector for the speakers.
http://i64.tinypic.com/2qvv2o5.jpg
The class D power amp switches at 480KHz, the standing supply current is 48mA (8mA to the LED) rising to less than 200mA for a very good domestic volume. The instruction specify a 2A supply but imo that isn't needed.
When the headphones are plugged in the switching power amp is cut off, which is a good thing and the standing current drops to 15mA (7mA with LED mod) so very suitable for battery operation as a headphone amplifier.
http://i68.tinypic.com/11b830k.jpg
The headphone output certainly goes loud and stays clean. All my headphones are 64 ohms impedance so I can't comment on how well it would drive high impedance phones.
Cheap as chips and excellent performance, apart from the blinding LED :rolleyes:
Postscript. Just tried it at 9V supply and it works no problem. It doesn't work at 5V supply.