Caiman passive output mod revealed

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Originally Posted by StanleyB

Now that the dust has settled a little I have had time to rethink the mod wiring.
The latest suggestion for trying out the mod requires only two pieces of wires. That means that you can try the mod out before deciding if you want to invest in two expensive caps.
Remove the line output opamp.
Solder two pieces of wires to the outer pins on the connector on the left side of the PCB (looking at the DAC from the front).
Push the bare ends of the left wire into pin 1 of the empty IC socket.
Push the bare ends of the rightt wire into pin 7 of the empty IC socket.

http://www.homehifi.co.uk/images/mods/caiman/f1.jpg

This way of doing it allows you to also add some improvements to the headphone section. The muting circuit is also fully functional, and there is a bit of HF filtering to remove some of any HF noise.

If you add the 68nF caps mod ( reddish caps in the picture) by replacing the 100nF ones (blue or yellow on the original PCB), the headphone amp performance will be almost indistinguishable from the original layout. With the THS4032, and some non-polarised caps I am trying out, my HD800 and D7000 have not pulled away significantly from my K701 and HD650 in terms of musicality, detail, and clarity. So for headphone users this alternative way of adding the mod is well worth a go.

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So this is my first foray into modding any gear so obviously I'm a bit wary of breaking something.
I played around with electronics in the past (HV, Tesla coils and solid state tesla coils) but I am more of a "paint by numbers" kind of guy due to my lack of understanding of electronic circuitry.
In other words, I can wield and iron, identify components, can follow a simple circuit diagram and love looking at pictures.
I want to do this mod to my Caiman but am having trouble struggling through this thread to find out exactly how to do it.
Stan's post above had all the info but the all important pictures are gone, is there an idiots how to anywhere with pretty illustrations?
Also, is there a "roadmap" of mods? I'm interested in trying out different op amps if this mod is successful.
Sorry for the very new newb posts.

Jim

Not directly answering your question (because I never did the above mod, only the original recommended passive output mod), the photo below is one I took some time ago showing the two passive coupling caps (green) inserted directly into the socket vacated by removing the op-amp board.

http://farm9.staticflickr.com/8070/8...1895c57d_b.jpg

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Originally Posted by MartinT

Not directly answering your question (because I never did the above mod, only the original recommended passive output mod), the photo below is one I took some time ago showing the two passive coupling caps (green) inserted directly into the socket vacated by removing the op-amp board.

http://farm9.staticflickr.com/8070/8...1895c57d_b.jpg

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And that's all that needs to be done? Remove the op amp board and install those caps?

Yes, you will lose the headphones (obviously!), check to polarity of the caps if using 'lytics, see page 12 post 117. You may need to check to input impedance of your amp so as to select a decent sized cap that wont cause a LF roll-off

Oh wow, it's easier than I thought. No cutting cables or routing wires.
Pull the board and insert the caps.
Thank you :)

I have had a lot of requests about the mods section that used to be on my website. I hope to have it back up in April so that there is a reference location for anyone wishing to try out any of the mods.

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Originally Posted by StanleyB

I have had a lot of requests about the mods section that used to be on my website. I hope to have it back up in April so that there is a reference location for anyone wishing to try out any of the mods.

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That would be awesome, Stan.

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Originally Posted by NRG

Yes, you will lose the headphones (obviously!), check to polarity of the caps if using 'lytics, see page 12 post 117. You may need to check to input impedance of your amp so as to select a decent sized cap that wont cause a LF roll-off

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Apparently my input impedance is:
Input impedance (R and C) 22 kohms+ 100 pF

And what caps should I be looking at for my rather varied listening tastes.
Portishead, Cash, Classical, unplugged sets etc?

With a 22K input impedance I would personally not go any lower than a 2.2uF cap...that gives a 3Hz roll off point, listening tests would confirm if Bass was OK. Any larger sized cap would be OK, it will limit you to 'lytics though and IME I found PolyProps better sounding, the 'lytics all having some coloration or sound of their own...

I agree with Neal, polypropylenes sound best but can be large and you may struggle to get the lid back on. On the other hand, 10uF bipolar Nichicon MUSE electrolytics sounded pretty good when I tried them.