Thanks for the encouraging words. Still a few things to do, such as Kim mentioned,shortening wires, and moving R16/17 and R14/15 closer to the pot and tube socket. It was just luck that I had used 2 ground wires and twisted them around the signal wires, I didn't expect any advantage over such short distances, (and yep also had to change C3 & C6 to the opposite polarity)
I noticed that the pot also has the occasional crackle when I move it, probably because it was cheap, I'm not sure how it will effect overall sound, or if there will be any major gains by using a more expensive audio pot.
The headphones I was using to test the amp yesterday were just an old pair of cheap JVCs. I've now tested it with my HD595 and ATH-M50s, it's still very quiet, although now I can detect a sight hiss at the very edge of my hearing (slightly more noise just after power on, but this drops away quickly, interestingly there is more noise with the case open), I wasn't sure if I was imagining it at first. I know mine are a long way from audiophile cans and are easy to drive without amp. I'm hoping to get some HD650's soon, so will give my thoughts later using something with a bit more impedance. At the moment 1/4 to 1/3 volume is a comfortable listen level for me (using an iPod classic as the source).
I'm very pleased with the sound so far, I don't have great deal to base it on, but it's definitely sounds better than the Cmoy and Cmoy Tube hybrid amps I previously built (not to take anything away from Fred_fred2004's kits, which are excellent), but the SSMH seems to have better resolution, I'm hearing new things in recordings that I had never noticed before. Looking forward to making an Objective 2 amp at some point in the future.
The case is just cheap metal one from an electronics shop, I have the same type I used for my alien DAC, I bought them to match, but I read afterwards that the SSMH might destroy the Alien so I haven't tried them together yet. I'm building a Skeleton Dac next which is a little cheaper so I might try the SSMH with that.
The power supply I am using is 48v 0.52A (rated 100-240v) made by FSP, Model # 025-1AD207A http://www.fspgroupusa.com/fsp0251ad207a/p/445.html It was $8 on ebay. (tested with a digital volt meter the voltage switches between 47.7 & 47.8 continusly (anyone know why?). The amperage is a little higher than the CISCO, I thought this might be good if I wanted to use LEDs. At the moment though I'm happy with the glow from the fillaments.
When I switch it off, the volume drops away to nothing and then comes back again for a second before dropping away completly (the power Led also follows this pattern), is this just the caps discharging?
The voltage at the heaters (measured between pins 4&5) is: 12.5 volts for both tubes.
The heat on the heat sinks still worries me,
I'm using standard 34x42x25,4mm heat sinks, I'm going to change to these http://www.aavid.com/products/standard/530002b02500g which are 30mm taller, hopefully it will improve things.
All the best, Andy
Edited by Frodo - 11/25/12 at 7:54am