Paul Hynes PSU for Caiman DAC

The dropout voltage of all the regulators I supplied to Martin will be less than 3v3 up to 1 amp (much more than the Caiman requires) as the logic level mosfets I have fitted for the output devices have low gate threshold voltages. So the 12 volt internal regulator should be fine with 16vdc input.

Regards
Paul

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Originally Posted by Paul Hynes

The dropout voltage of all the regulators I supplied to Martin will be less than 3v3 up to 1 amp (much more than the Caiman requires) as the logic level mosfets I have fitted for the output devices have low gate threshold voltages. So the 12 volt internal regulator should be fine with 16vdc input.

Regards
Paul

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Thanks Paul, that clears that up. :)

I was just a bit worried as from what I understand the headphone output on the Caiman takes an unregulated feed directly from the DC input. So going over 16V input could cause issues with cap values on the opamp board. The main resevoir cap on the Caiman is also 16V but I know Martin has upgraded that, so that's fine.

Sorry for the slight thread hijack Martin, I just wanted to clear that up as I thought it was important. :cool:

Good luck with the regulator swap. :)

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Originally Posted by Paul Hynes

That LED is bright! You can adjust the light output by increasing the value of the axial resistor to the right of the reservoir capacitors until you have the desired light level.

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I guessed that doubling it would be about right, and it was. I replaced the 4k7 resistor with a 10k and the light level is now fine.

I've now installed the +5V and +12V regulators inside the Caiman.

Showing the PCBs after installation of the two PH regulator modules. It's a tight fit but it can be done and I used double-sided sticky pads to hold them in place.
http://www.mtc.me.uk/images/P1000485.jpg

This is a complete list of the mods made to these boards:
- All audio path electrolytics replaced with Elna Silmic II
- Main 10,000uF reservoir cap replaced with 2 x 10uF Panasonic film caps
- PSU protection diode replaced with a wire link
- Op-amp board and socket removed and replaced with 2 x 2.2uF Auricap coupling caps
- 3-pin regs replaced with +5V and +12V PH modules

The sound quality after replacing the Dexa regs was a smaller but further improvement in refinement and focus. I noticed especially a very high level of transparency with female voice and increased heft in the bass.

Listening to Barcelona from Jewel's Spirit album usually tells me all I need to know about sound quality. Her beautiful but powerful voice soars now with no hint of harshness, underpinned by a very potent bass line that is more textured than ever while having no remaining hint of boom. It's quite a performance and the Caiman sounds frankly fantastic playing it.

All in all a very satisfying modding experience. I'm going to leave well alone now, let it burn in some more and enjoy the fruits of my labours.