Headamp with LDR attenuator
Jul 11, 2010 at 8:12 AM Thread Starter Post #1 of 1

lordearl

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I've recently finished my latest project and have put together some photos and a few comments after about 50 hours of burn-in time.
 
This unit has two functions:
(1) Headphone Amp
(2) Preamp
 
There is an LDR volume attenuator which controls the Headphone Amp volume, and also the preamp volume.
 
There are two inputs, and also an output selector which allows the choice between the preamp output direct from the LDR volume control - or from the Headamp used as a linestage.
 
Each PCB was bought from fellow Aussie Greg Ball, who runs an online DIY shop here:
 
http://www.ska-audio.com/Forum/YaBB.pl?custompage=products
 
I've documented the entire build in the following thread - so if you're interested you can see the entire process, including how certain parts (caps, resistors) were selected:
 
http://www.ska-audio.com/Forum/YaBB.pl?num=1271164730
 
After a large amount of testing with opamps, I've settled on the LME49720HA (basically the LM4562 in a metal can) because it works really well in conjunction with the HeadAmp to give a transparent, well defined sound.
 
As a result of using an excellent dual regulated power supply, with the transformer being in a separate box, the background is silent, no buzz or hums - on both the preamp output and also on the headphones.
 
I'll post some more impressions after further listening, but needless to say (both because of sound quality and because I built it!) it has replaced both my Xindak preamp and also my Vincent headphone amp.  The excellent definition on the lower end of the sound spectrum matches really well with my K701s - it just brings a little more bass to recordings that often seemed lackluster to me (e.g. Pink Floyd's Animals!).
 
For now here's some photos - more thoughts to follow later.
 

 




 

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