The events unfolding around the world at the moment are having impacts unheard of for generations. I am lucky; I’m well, I still have a job at the moment and am working from home, but, like many, that job may not be there for much longer. Whilst I am probably busier than normal as I adapt to my new work circumstances, playing around with audio gear in my spare time takes me away from watching constant news updates. I’m grateful I have such a diversion whilst we are in lockdown. The weather has improved immensely after one of the wettest winters for decades here in the UK. The sun is out, temperatures are rising and normally I would have headed off for some camping and walking in the hills.
This is a brief update of a previous post where I detailed my build of the 2nd harmonic generator by Nelson Pass. I now have a nice Pass clone enclosure, just £26 including postage. The power requirement for the H2 as specified is a regulated 24V DC wall wart rated at 0.5A, and Pass added some passive filtering after the LM317 regulator. As I had some spare filtered PSU boards from Slowdiyer, I bought a Meanwell IRM-15-24 (634mA) from RS for £9. For the CLC filter, I used a 150uH inductor as these were left over from a previous PSU build, and combined it with 470uF capacitors. I also used one of Slowdiyer’s mounting boards for the Alps 50K RK27 potentiometer. This has provision for terminal blocks and also a connection for a ground lead to the chassis.
The buzzing noted when I tested the board originally has now disappeared as expected. I tried it as a preamp into both my Amp Camp Amp and my new ICEPower Class D amp. The sound is actually quite good, such that I think I’ll leave it in place for a while.
4 thoughts on “Nelson Pass H2 Harmonic Generator – Update”
That’s a nicely put together unit you’ve made. I’m very interested in the case you’ve used, could you tell me where got it from please?
Thank you. I bought it from ebay, but you can get them from other Chinese sites such as Aliexpress. Search for 1506 Pass amplifier chassis and that should get you there. The 1506 relates to the size (150mm width x 60mm height), so there may be other versions of the same design.
Can I use it as preamp between DAC and Whammy headphone amplifier ?
Hi, sorry for the delay in replying, I was away on holiday. You could indeed use it as a preamp. Nelson Pass said this about it: