Convert headphone amp power supply?

[jfall]

I have a headphone amp that was designed to be portable, thus it only runs off of two 9 volt batteries. I find that I mostly use the amp while at home on my computer, so I want to find a way to power it without using batteries. Is this possible? The amp has the following specs if it matters:

Bud extruded aluminum enclosure
Lambda PCB
AD823 and AD8055 opamps
Class-A bias
Buffered outputs
Discrete isolated ground channel
470uf 25V power capacitors
Hand matched Vishay-Dale 1% Resistors
Jung Multiloop feedback topology
Texas Instruments TLE2426 "rail splitter" based buffered virtual ground
Switchcraft 1/8" input and output jacks
Panasonic EVJ series volume control
Blue power indicator LED

 

[jfall]

Here are some pics of the innards

amp1.jpg
amp2.jpg
amp3.jpg

 

[Kaido]

Sure, but batteries are supposed to make for cleaner sound. If nobody can help you here, check out the head-fi.org forums.

 

[jfall]

Originally posted by: Kaido
Sure, but batteries are supposed to make for cleaner sound. If nobody can help you here, check out the head-fi.org forums.

Really? I never heard that before.. maybe less line noise? Anyways, I'm sick of buying and replacing the batteries in this thing all the time, i'd love to be able to just plug it in

 

[mercanucaribe]

Try hooking it up to your computer's 12v, or buy an 18v AC adapter.

 

[IAteYourMother]

you could make a trickle charging supply

 

[Howard]

Do you have the schematic?

http://sound.westhost.com/project43.htm

 

[DayLaPaul]

Yea it should be cake with the schematic. I know the CMOY that I made accepted both battery and A/C. It would even disconnect the battery when plugged into the wall.

 

[mercanucaribe]

What is this schematic business? Why can't he just plug in an 18v AC adapter?

 

[jfall]

Originally posted by: mercanucaribe
What is this schematic business? Why can't he just plug in an 18v AC adapter?

Where do you suggest I "plug in" the adapter? This amp only takes batteries, there is no where that I can plug in an adapter

 

[Minerva]

What you need is a 9 volt battery eliminator. If the batts are in parallel you only need one. If in series you will need a supply with higher voltage or an inverter. Just remember if anything else is plugged in to the wall at the same time you may get ground loop noise.

 

[jfall]

Originally posted by: Minerva
What you need is a 9 volt battery eliminator. If the batts are in parallel you only need one. If in series you will need a supply with higher voltage or an inverter. Just remember if anything else is plugged in to the wall at the same time you may get ground loop noise.

That looks like it would work. How can I tell if they are in series or parallel?

 

[Minerva]

If the pos and neg are connected together on the the two batts, you're in series. If both pos and neg run to the board you're parallel. Parallel just doubles the run time. Series gives more voltage but will cut the run time if the current is the same as a single batt.

 

[mercanucaribe]

Originally posted by: jfall

Originally posted by: mercanucaribe
What is this schematic business? Why can't he just plug in an 18v AC adapter?

Where do you suggest I "plug in" the adapter? This amp only takes batteries, there is no where that I can plug in an adapter

http://www.thesciencefair.com/Merchant2...phics/00000001/9VLeadSide1604_31_M.jpg

That will plug in where a 9v battery plugs in.

 

[Howard]

Originally posted by: Minerva
If the pos and neg are connected together on the the two batts, you're in series. If both pos and neg run to the board you're parallel. Parallel just doubles the run time. Series gives more voltage but will cut the run time if the current is the same as a single batt.

Can you get a virtual ground with a parallel supply?

 

[Born2bwire]

Originally posted by: Howard

Originally posted by: Minerva
If the pos and neg are connected together on the the two batts, you're in series. If both pos and neg run to the board you're parallel. Parallel just doubles the run time. Series gives more voltage but will cut the run time if the current is the same as a single batt.

Can you get a virtual ground with a parallel supply?

Yes. In his specific case he has the TLE2426 rail splitter which provides the ground (the ground reference is at half the power supply voltage).

 

[jfall]

I wrote the maker of the amp, and he had this to say:

The Lambda 9v's run in series...you could use that battery eliminator if you bridged the terminals on the second 9v clip...a 9v clip with the leads twisted together from radio shack would work well!