Caiman Mods

[MartinT]

That's great - thanks Leo. Doing them now.

[leo]

No probs Martin, let us know how you get on

[MartinT]

Done. Oh yes, another subtle improvement in clarity and focus. I just watched Quantum of Solace on Sky HD (now that the snow's off my dish) and the soundtrack is superbly delineated and detailed. This is one very fine DAC indeed and worth the modding cost.

[MartinT]

More information on the Dexa 'NewClassD' regulators, made in Denmark:

http://www.newclassd.com/index.php?page=70

[here we go again]

as promised several days ago a few pics of my Caiman - at the moment!

1. The output board with the Wima film caps - after listening to this for a week or so I've decided to keep them - 3u3 was the largest value i could find whilst keeping the physical size small enough to fit neatly - I've got away with it with my Puresound and theres no hint of any bass lightness. At the same time I fitted a couple of ZA's to decouple the non-inverting input too. - haven't touched the headphone amp yet!


2. The regulator board fitted neatly to the rear panel - at the moment this contains 3 x LM2940 +5v regs with each having a small inductor and caps to keep it stable. Eventually i will swap out each one with an Audiocom super reg i have in another project - see what difference it makes. I also have another few of those Murata 7805SR switching regs which will go in here at some point - for the time being i was just curious to see what difference it would make if i seperated the supplies. Currently these 3 feed the Wolfson dig. supply, the CS dig. supply and CS analogue supply. The board is fed from the incoming 15V supply - I added a couple of veropins to some redundant padded holes in the board - you can just see one of them in the last pic.


3. An overview of the digital board showing the Murata reg fitted in the original location and a smattering of cap upgrades - ZA's, OScons and the odd BG I had lying around. The multicoloured link wires replaced the original grey ribbon which wasn't really flexible enough to allow for repetitive board removals! The replacement caps haven't been in too long yet but after just a few hours the low freqs have more slam - and the highs seem crisper - hopefully things will improve further as things settle in.


This is work in progress and I have some other ideas but am trying to keep it slow - it's quite a challenge to work within the tight spaces but I'm enjoying it - be warned though, it is not for the inexperienced - especially splitting the supplies which can be a real headache. This thing is certainly a giant killer though and I have never heard my system (Puresound/Triangle) sound like it does at the moment - all those little reverb clues in the music are much more evident now - puts a huge grin on your face!!

Oh and something I noticed recently - Farnell are waivering the US delivery charge for the remainder of January - this means that the Murata +12V switching regs can be had for less than £15 - I've just ordered a couple - as I mentioned in my previous post the +5v ones are UK stock and are a bit less than £12 each - they are great value for money and in my experience give some of the so called 'low-noise' regs a run for their money.

[MartinT]

Nice work here-we-go-again (what is your name?), did you work from a circuit diagram or did you trace the +5V rails from the PCB tracks? What have you done about +12V - I see the heatsink is missing, but what regulator have you got in there?

[here we go again]

hi Martin - glad you like - oh and a circuit diagram would be great!! but no I just followed the +5v as it meandered it's way around the board. Study and print off the datasheets for the receiver and DAC then split/seperate as necessary. The main difficulty arises from the fact that this is obviously a double sided board and the tracks frequently hop from one side to the other through plated holes - check, check, then check again BOTH SIDES before cutting the track at a suitable point, drilling a hole and wiring up - remembering to include the decoupling cap and bypass in the new supply. You could get away without drilling but I wanted it to look reasonably neat.

The receiver wasn't too difficult to suss out and of course it's a larger package which helps - the DAC is not funny at all and takes much head scratching. The positioning of the DAC de-coupling caps and bypasses around the chip makes seperating the supplies here really tricky - but just about possible. I hope I don't sound patronising, but it is seriously tricky and only for the experienced - so very easy to ruin the thing.

Regarding the +12v, I haven't attacked that yet - just removed the heatsink in preparation while the board was out - it doesn't even get warm.

oh and my name's Graeme - sorry must get a sig. sorted sometime!

[HighFidelityGuy]

I'd like to try the Murata reg's but as Stan said the shipping is a bit pricey. Orders over £50 get free delivery on Mouser, so if two or three (or more) other people are interested in trying these then I'd be happy to place the order and post them out. I'll order in pairs (one 7805SR-C and one 7812SR-C) and only charge the price it costs me to order them plus the postage to you, which should be cheap. If anyone is interested drop me a PM.

[chrism]

Top idea Dave.

Please count me in and I have also sent you a pm. Anyone done both regs and liked what they heard?

Regards

Chris

[MartinT]

Anyone done both regs and liked what they heard?

Yes, I like the improvement in focus, imaging and detail very much.