XP-7 headamp clone…

Another build I’ve managed to finish during the past week is the XP7 clone (originally shown here). As I explaned originally this is more or less a standard OPA+BUF634 amplifier with the only real “USPs” of this implementation being the use of AD797 opamps and lower gain resistor values than usual – both of which should help reduce noise.

I’ve done my bit for noise reduction as well by making the amp powered by two 9V batteries – I haven’t tested the battery life yet, but hopefully it isn’t too bad 🙂

Regardless of that I don’t particularly need another headphone amp as I don’t really listen to headphones that often any more. However since this one is battery powered I will not pack it too far away, because a battery powered amp is quite useful for testing (due to no ground loops). And, after a little bit of listening to the finished product I have to say that it doesn’t actually sound bad at all…

Nudging projects forward…

Sometimes my projects are “stationary” for a very long time, and then a small nudge from another project is just what was needed to get them going again.

The current example is this (eBay) clone of an Ray Samuels Audio XP-7 headphone amp, which has been needing a custom front panel for several years now. Originally I tried drilling the case myself with a stepped bit, but that simply wasn’t accurate enough and so I needed to remeasure and do a custom panel instead. I’d been dreading this because of the frustration I feel when it doesn’t work out (and custom front panels are not cheap), but spurred on by my recent success of doing the back panel for the ES9038 dac I decided to give it a go, and this time it actually also worked on the first try 🙂

The XP-7 is a pretty straightforward headamp design with an opamp and a BUF634 output buffer in the feedback loop, as was the “state of the art” around 15 years ago 😀 . The only things that stand out in the clone design are the feedback resistor values that are lower than usual (which means lower noise) and then the chosen opamp which is an AD797 that also has very low noise. Together they should make a very dynamic amplifier and I remember being pleasantly surprised when I tested the bare board. However, putting it in a case should make is easier to try again (although to be honest I do next to no headphone listening these days).

The battery supply is two 9V batteries which is normally very impractical, but it does also have some benefits and I actually use a battery-powered CMoy-style headamp for a lot of testing (no risk of ground loops etc.). There’s still a bit of wiring to do here, but it’s always a nice feeling to move something along that has been sitting on the shelf for far too long 🙂