Caiman Mods

[TheGreenManalishi]

Certainly peeved that you have questioned my sincerity.
When Covenant and a couple of other guys suggested a TC-7520 with a WM8716 instead of the PCM1716, I took note and eventually did decide to build such an item after further research.

Anyhow, let's think nothing of it. Best that you pursue your initial plans with regards to the person you intended to submit your DAC to for further upgrades.

Will do, i appreciate your input.

[shuggz]

Thanks guys - its precisely that im impressed with the Caiman that im sure that it can be a long term source (*but lets face it im sure another 150 quids worth of components would improve it?)

My thought process was that a 500quid headphone amp might be a little too revealing for the DAC?

S

Improve it in what way? do you have a reference point or are you just taking this persons word as gospel.
You might find that you could reap more rewards from simply changing the toslink/coax cable.

[StanleyB]

The bad thing about driving high-end headphones like my Sennheiser HD800 is that a high-end headphone amp is required to get the best reproduction.
The good thing is that the Caiman headphone amp is capable enough to compete against stand alone high-end headphone amp.

But driving the larger and more revealing HD800 drivers requires a bit of extra attention in the circuitry if the intention is to extract every bit of sound in the digital stream.

[StanleyB]

To drive the larger HD800 drivers with the least possible distortion requires a larger damping ability from the headphone driver opamp. I selected the THS4032CD for that job, but hope to try out the TPA6120 as well.
I have always believed that capacitors in the signal path should be non-polarized. That's what they use in speakers after all. But finding low voltage small footprint non-polarized caps can be a tricky thing. I did manage to source some 47uF/16V types to replace the 4uF/16V polarized ones in the Caiman headamp. I also used the same caps in the opamp bias circuit. I'll keep an eye on that to see if it makes a difference or not.

The red caps are 68nF, instead of the original 47nF on PCB. This change gives a bit more width to the bass spectrum.
The 100pF caps in the HF feedback path of the headphone opamp has been removed. This was only decided upon after I fitted the new regulators (see next pic). Without the special regulators, the sound was a bit grainy with the caps removed.

The HD800 has a 300 ohms impedance. So I adjusted the gain of the amp upwards. The 68K resistors in the headmp feedback loop have been replaced with some 94K ones I had in my component box. I reckon 100K would be just fine as well.

[StanleyB]

The standard regulators are not the best in the world. They are however adequate for most applications. However, the HD800 needs a lot more attention in the PSU area. So I opted to use the best regulators money can buy. For the 5V I used the Murata 7805SR, and the front regulator is the Murata 7812SR.

These regulators are not available in the UK, so I had to import them all the way from the US at quite considerable cost. Hopefully someone will start selling them in the UK very soon. They have a ripple voltage of just 10mV and make a considerable impact on the amount of extra detail that can be heard in the HD800.

[Shanedudddy2]

Explanation as well would be nice?

[Gazjam]

Stan you're teasing again!

*edit*
thanks for the update Stan, looks a good one for the headphone users out there.

[therockst4r]

I see some different caps, regulators, and opamps, did I miss anything? Please tell us what effect these mods had on the sound, if you are willing to share.

[Shanedudddy2]

Also whats the small board on the right...is that a battery? *shrug
detailed explanations pleeeaasse. lol

[StanleyB]

There are still a view more parts that I want to try out in the circuit, so this is work in progress.

I had to buy some of the caps in bulk in order to get them. If anyone with genuine soldering experience is interested in a set, I can work out a fair price in exchange. It is likely to be less than a fiver to cover P&P.