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[FS] Ian Canada OPA861 I/V Hat

J

James Evans

Bedroom Bodger
Bought this a couple of weeks ago and should have read the manual in more detail before doing so. It's intended for balanced use only really and I'm S/E throughout. The manual states S/E output for function testing only. Doh. Tested, and all working fine, but I am inevitably not getting the most out of it. Needs a +-5v PSU. Need to free up funds for other stuff, so, on it goes.

Bought direct from Ian at 129 USD, which is £103, Audiophonics have them at 185 Euro which is £158!

Selling for £90 inc uk postage. Will post overseas at cost.

Can sort out photos if needed, details below

https://github.com/iancanada/DocumentDownload/blob/master/RPiDacHAT/IVboards/OPA861IV/OPA861IV.pdf

https://www.audiophonics.fr/en/dac-...-balanced-zero-feedback-iv-stage-p-17013.html
 
I have a couple of Pi streamers, so I was pondering whether I needed something like this. I didn't know what an I/V stage was, so just for fun I asked Chat GPT:

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An I/V stage is a circuit that converts the current output of a digital-to-analog converter (DAC) into a voltage signal that can be amplified and processed by an audio device. It is also called a transimpedance amplifier or a current-to-voltage converter.

There are different ways to design an I/V stage, such as using passive components (resistors or transformers), active components (op-amps or discrete transistors), or a combination of both. Each method has its advantages and disadvantages, depending on factors such as noise, distortion, linearity, slew rate, impedance matching, and power supply quality.

Some of the trade-offs involved in choosing an I/V stage are:
  • Passive resistive I/V stages are simple and cheap, but they can degrade the signal integrity and dynamics, cause impedance mismatch, and require high gain in the following stages.
  • Passive transformer I/V stages can provide good isolation and impedance matching, but they are bulky, expensive, and may introduce nonlinearities and frequency response issues.
  • Active op-amp I/V stages can offer low noise, high linearity, and high slew rate, but they depend on the quality of the op-amp and the power supply, and may introduce negative feedback and over-engineering problems.
  • Active discrete I/V stages can offer more flexibility and customization, but they require more design skill and component selection, and may suffer from stability and linearity issues.
Ultimately, the choice of an I/V stage depends on the goals and preferences of the designer and the listener. There is no definitive answer to which method is superior or why. Some people may prefer a simple and transparent I/V stage that preserves the original signal as much as possible. Others may prefer a more complex and colored I/V stage that adds some character or flavor to the sound. The best way to find out what suits you is to experiment with different options and listen for yourself.
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Given I have a bunch of excellent DACs on-hand, and many other projects on the go, I think I don't need this today. ;)
 
Can't really argue with that :) I would think this hat is really only designed to be used with one of Ian's ESS dac hat boards. Not sure if it could be used with other pi dac hats.
 
I was originally thinking I would try to pass the signal from a Pi to the DAC via I²S. Consequently, I do have an IAN CANADA HDMIpi MKII Transmitter I2S / DSD / DoP to HDMI. I've not tried it yet, though, and since then I bot an Denafrips Iris to feed the Pontus II. Unfortunately, I wasn't able to get I²S to work between them, even after trying a few cables. I'm currently running AES/EBU, which sounds very good.

I should sell that board, but I dislike selling stuff. Too often, the time required to sell it exceeds the value of the thing. :rolleyes:
 
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