msknight
100+ Head-Fier
- Joined
- May 10, 2016
- Posts
- 163
- Likes
- 43
OK ... this is going to be a long and strange one.
I have a Benq monitor with headphone output. I wanted to drive a pair of old Logitech speakers (8 ohm, passive) but obviously it was going to need an amplifier in line. I wanted to avoid extra transformers so I wanted to power from an existing USB 5V port. Shouldn't be a problem... I thought. Oh boy was I wrong.
I started by putting together my own circuit - http://msknight.com/technilife/?p=1298 - and gutted an A910 from Line 5 because it worked from 9V AC... and I'm a bit nervous of having odd transformers around because I've already cost myself a small fortune by plugging a 12v transformer into a 5v device and blowing it up.
However, despite it working - http://msknight.com/technilife/?p=1327 - the circuit suffers from hum which I'm presuming is on the power line, and that's difficult to stop.
So... I've tried some other amplifiers and circuits and come up short. I tried a Douk U3 but that's only meant for headphones and didn't quite generate enough to drive the speakers properly. I also tried a small, one chip speaker amplifiers that outputs 3W - https://www.ebay.co.uk/itm/114853195930
Actually, I've currently got the Douk outputting to the 3W amp and it's reasonable, but I could do with more. About 5W.
Ultimate target is a small amplifier roughly the size of the Douk or A910, which I can plug the 8ohm speakers in to and get a reasonable amplification to about 5W or possibly a little more... but obviously feeding from a 5V USB power supply.
I have actually tried to admit defeat and source another A910, but no joy; they're discontinued and I can't work out what replaces it... but if anyone knows of a small amplifier that fits what I'm looking for... it's this group
I have a Benq monitor with headphone output. I wanted to drive a pair of old Logitech speakers (8 ohm, passive) but obviously it was going to need an amplifier in line. I wanted to avoid extra transformers so I wanted to power from an existing USB 5V port. Shouldn't be a problem... I thought. Oh boy was I wrong.
I started by putting together my own circuit - http://msknight.com/technilife/?p=1298 - and gutted an A910 from Line 5 because it worked from 9V AC... and I'm a bit nervous of having odd transformers around because I've already cost myself a small fortune by plugging a 12v transformer into a 5v device and blowing it up.
However, despite it working - http://msknight.com/technilife/?p=1327 - the circuit suffers from hum which I'm presuming is on the power line, and that's difficult to stop.
So... I've tried some other amplifiers and circuits and come up short. I tried a Douk U3 but that's only meant for headphones and didn't quite generate enough to drive the speakers properly. I also tried a small, one chip speaker amplifiers that outputs 3W - https://www.ebay.co.uk/itm/114853195930
Actually, I've currently got the Douk outputting to the 3W amp and it's reasonable, but I could do with more. About 5W.
Ultimate target is a small amplifier roughly the size of the Douk or A910, which I can plug the 8ohm speakers in to and get a reasonable amplification to about 5W or possibly a little more... but obviously feeding from a 5V USB power supply.
I have actually tried to admit defeat and source another A910, but no joy; they're discontinued and I can't work out what replaces it... but if anyone knows of a small amplifier that fits what I'm looking for... it's this group
