Headphone Amplifier - JLH Class A
Miles Campbell
This is my first main post to the london-hack-space, and my first meeting will be tomorrow night.
I hope everyone finds this of some interest.
So lets begin, is anyone interested in building a Class A Headphone amplifier ??
Today on ebay I found a Company producing a populated PCB so all that is required is a case, power supply and a couple of sockets.
http://shop.ebay.co.uk/?_from=R40&_trksid=p4634.m570.l1313&_nkw=NEW+Ver+JHL+Class+A+Headphone+amplifier+PRE+AMP+KIT+DIY&_sacat=See-All-Categories
or
http://completed.shop.ebay.co.uk/i.html?rt=nc&LH_Complete=1&_nkw=NEW%20Ver%20JHL%20Class%20A%20Headphone%20amplifier%20PRE%20AMP%20KIT%20DIY&_fln=1&_trksid=p3286.c0.m283&_rdc=1
After some discussion we have agreed a buy-it-now price of £8 a unit + P&P + Import duty
This offer looks to good to be true and in my opinion is a bargain
The picture and schematic can be found attached
The original Circuit 1 can be found here : http://www.tcaas.btinternet.co.uk/jlhphones.htm
There is a thread running on DIYAudio
http://www.diyaudio.com/forums/headphones/159202-jlh-headphone-amp-10.html#post2485992
It has to be said there are some difference between circuit 1 above and the supplied diagram, but these can be simply changed back if required.
-- Questions --
My plan is to build a number for comparison
- As manufactured
- Conversion to Circuit 1
- Conversion to Circuit 2
Why this amp?
- I have a great deal of respect for the work of JHL
His designs were well made, very considered and clever
His life's work can be found here http://www.tcaas.btinternet.co.uk/jlharticles.htm
Is the power supply PSU difficult to make?
- A single transformer and an on/off
Can the basic amp be upgraded or mod'ed ??
- Yes there are a number of ares that can be considered
- Capacitors
- Volume Control
- Power supply
Miles, Can you help with the build and making of the case?
- Yes of course
Let me know if you fancy having a go ?
After this I guess will be a USB DAC !
Miles
