I think I'll be painting my small subwoofer in some shade of cherry or wine red. I just need to sand it down once more and give it one final layer of MDF Primer. Hopefully, all dents and small damaged points will be gone. I won't get my hopes up though.

This blog is not about audio. Or at least not in the sense of a design or equipment discussion. It's about how we as humans tick, and possible (probable?) implications for how we form opinions and views about what we hear, about a particular design or sound.

My long-standing interest in this area was recently triggered again by a couple of posts from Mark4w, and a book he recommended (Thinking, Fast and Slow, by Daniel Kahneman). At about the time I received the book I also fell into a scientific discussion on the TV about the process our brain goes through to form an opinion and serve that up to our conscience as 'this is how it is'.

I thought back about all the discussions I've had on diyaudio about sighted versus blind listening. Without opening up Pandora's box yet again, in a nutshell: The brain uses every input it can get its hand on to form an opinion. So when you listen to, say, a new amp, the brain not only uses the sound coming in through your ears,...

How to set up the spell checker.

Surprise!

Spell check is NOT in the DIYAudio software,
it is part of your browser.

Set up is simple. Follow these
general steps:

On the menu bar select and hold tools:



Then, drag down and selection Options:







Then from the tool options scroll down and select Advanced:




Then at the bottom click on the check box, to
put a check in it:



Close the window, restart your browser, that is it....

Two boards, each board configurable for line and headphone variants. Powered by nominal +12 V -12 V split regulated supply, though 9-15 V rails can be used without modification.

Images of the audio equipment I have access to.

Following on from this post and this post, we arrive in time for the holidays with Project Unity. Merry Christmas everyone.

Four circuits: Unity, Unity H, Unity B, Unity BH. line preamp, Headphone amp, line Buffer, Headphone Buffer respectively, all derived from a common base circuit called Unity Root. Unity Root is conceptual, it exists only as a reference so you can see more clearly how the four working variants relate to each other.

It's the "all for one, and one for all" approach to diyaudio, a single research and development line applied to a range of applications, feedback from any of the applications brought back to apply to the line in general.

This simplifies not just the circuit development, similar efficiency is also brought to the documentation, board layout design, and BOM... about which I'll have more to say in a bit.

I've come this far so I might as well complete the trifecta.

This is the X-Reg circuit, with a new layout and component numbering to match the new S-Reg and Z-Reg boards. Each is a drop in replacement for the other.

Like its siblings, the X-Reg is a low current voltage regulator for line level audio. The output is about 9 V (adjustable up to 12 V) and the maximum load current is 50 mA without heatsinks, 100~150 mA with small heatsinks on Q1,2.

It is not a true regulator as there is no fixed reference and instead the output voltage is defined relative to the input voltage. The high open loop gain of the op amp is harnessed for very low noise and very high ripple rejection. It is necessarily a high feedback approach.

So, there you are: three mix-and-match power supply options for all your low voltage, low current audio needs.

Companion regulator to the S-Reg. Same board dimensions and connection layout. For line level audio.

Same idea as before rectified 2x12 VAC input, +/- 11 V output. 50 mA max output current unless the transistors are heatsinked.

There is a small amount of over-current protection afforded by R3,4 but do not short the output for all but the shortest of transients.

Eagle/Gerber files attached, so you can go get this made yourself, optinally with whatever modifications you need.

I've use this regulator circuit in my Sapphire headphone amplifier. It's a simple and modest circuit but I feel it works really well in practice as long as the audio circuitry it powers has reasonable PSRR. No feedback means no out-of-band noise or instability, even as the output impedance remains low.

S-reg voltage shunt-source regulator for line-level audio circuits.

This is designed to accept rectified 12x2 VAC input, producing +/-12 V output split rails.

Features soft-start and over-current protection, standard configurations for load currents up to 50 mA. High performance: 80 dB ripple rejection up to 100 kHz.

update: BOM uploaded
update: web page (stub)

The time of year where I like to draw up some plans for the next 12 months.

This year’s output looked something as follows,

• Lowering the noise floor by shielding the power transformers of my Sapphire3 headphone amp (and eventually replacing them with Triad VPM shielded toroidal medical transfomers)
  
• Developing the CrystalFET phono stage.
  
• Developing the the VSPSX and bboard 2 to the point of getting the boards fabbed.
  
• Tweaking the Sapphire3 headphone amp slightly to use as a preamplifier.

At the end of all this I find myself sitting on four different voltage regulator circuits, several variants of the transistor output diamond buffer, five phono stages variants, and a couple of nebulous ideas about developing a discrete voltage gain amplifier.

I'm considering how to package this all up in such a way as to best appeal to diyaudio builders of widely varying application needs and skill levels while keeping a simple...