Arcam Alpha mods

[AndrewGM]

That pic is obscene - a moderator needs to look at that and remove it.

All those Black Gates......pah....lottery winners

[Thomo]

Simon. I'd try one of those big psu's for the dac supply rather than the decoder, unless you already have something tasty on those.

Lee.

[SimontY]

Andrew, there are no BGs in my pic and no lottery winner here! The dark caps are just Cerafines mostly, red also Cerafine and Brown 99% Elna Silmics.

Lee, the DAC has just been treated to 2 x 22,000uF Si caps, and its psu is onboard so that's all that will fit. Likewise clock and RAM supplies are also onboard.

Only decoder, filter, output stage and servo driver supplies are external. Servo runs on Myltics I think and output stage on F&T (all the same basically and good).

[Thomo]

Excellent stuff Simon. Silmics can sound good, but you need to parallel them like that imho.

Lee.

[AndrewGM]

I was kidding, sorry

[SimontY]

Well I've connected up the two banks of 20 Silmics. It fits in the external psu just fine after a minor re-jigging. I'm going to try CRC filtering as Lee suggested to me in private. I will simply place a series resistor from each cap bank leading to another, smaller bunch of Silmics. I've not worked out exactly what value the resistors should be but I'll start with a bit of trial and error looking for a reasonable voltage drop.

[SimontY]

Alright, here we go. I finished my CRC supplies for decoder and digital filter.

It goes like this. Decoder: 20 x 470u > 10 x 33R 1/2W in series > 10 x 470u
Digital filter: 20 x 470u > 3 x 18R 5W in series > 10 x 470u

Each supply drops about 7-9V across the resistors. The resistors get warm but are over-rated quite heavily (I actually did some basic maths for once).

The regulators now have to regulate less and have a supply surely almost completely devoid of any ripple. Hopefully the player will run a bit cooler inside, with more heat spread into the psu box, which was previously quite cool-running. Curiously the bridge rectifier that powers the digital filter supply now gets warm to the touch.

[AndrewGM]

That looks really neat and tidy in there and your caps look like works of art.

What does it sound like ?

[SimontY]

Thanks Andrew, it's not that neat, just neat enough to be sure it works properly and won't fail.

I've been listening most evening and it seems to have improved matters. The sound seems more dynamic and detailed with deeper bass and a smoother midrange.

Combined with the cap upgrades on my DAC chip and also in my preamp and my bass power amp the gains are substantial! Diana Krall sounds magnificent right now!

[AndrewGM]

Blimey - just when you think you may have maxed out you then find ' more '
I'm glad all that effort paid off for you.
I won't be able to try it sadly but hey, I'm still gob smacked by the bigger caps on the DAC tbh
....and it was so cheap to do !!

I like those ones