Evolution of a concept…

I’ve been playing with the (somewhat) unusual combination of a class A amp and a switching PSU before (here). The previous version worked quite well, but even as I was building it I though that there might be scope for optimisation and for making it smaller – which to be honest was my goal all along.

The amplifier section is now my own version of the JLH 1969 with MJL21196 output transistors (because I had them available). The heat sinks are the same surplus items I’ve used before – because they are cheap and exactly the right size for what I wanted to do 🙂

As I observed in the previous post, the chosen PSU was more than a little overspec’ed for the job, but as luck would have it a much better choice came up recently – the Mean Well EPP-150-27. These are “next generation” supplies (i.e. more compact at 2” x 4”), there’s a convenient 12V aux supply for a fan etc. and the 27V output voltage is spot on for the JLH. There’s a smaller 100W version that could be used as well, but since I could get these as surplus items off ebay there was no incentive to do that 😀

I’ve also been looking at getting some more quiet fans, but I’ve now realised that the most annoying noise from fan-cooling doesn’t really come from the fan itself but from the sound of air rushing through the various holes in the enclosure. Once I’ve done the final design I’ll have to test what can be done to keep the amps as quiet as possible. The noise level on the first iteration was OK, but definitely with room for improvement.

To marry the parts together I came up with a “central core” design where the amp and the PSU are bolted to the heat sink tunnel and that’s about what I have done so far. The rest of the mechanics are in the works and there are a few (as yet undisclosed) additions that I will add as well in due time 😀

Advertisements

2 Responses to Evolution of a concept…

  1. Pingback: JLH Evo Update | theslowdiyer

  2. Pingback: Tripath TK2050 monos… | theslowdiyer

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: