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RJM Audio

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300x25x0.5mm strips of copper wrapped around my toroidal power transformers and held in place with cable ties.

...DIY magnetic shielding...
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RJM Audio

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Today I replaced the suspension elastic in my AKG K702 headphones. It was a far from trivial repair, as most of the the plastic parts are held together by clips rather than screws and every step risks snapping something.

I have to say I feel this is a design flaw. When the headband adjustment relies on such an obviously short life part like rubber elastic (like the ones girls use to tie their hair back) the headphone should be designed to allow the easy and frequent replacement of this part.
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DFA - design for assembly. The flaw in that technique was not considering repair. And most engineers had no practical experience in field repairs.
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RJM Audio

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What the heck are these?
Seriously.
The idea that you can ground a component by connecting it to another (ungrounded) component is not electrically valid. Is it just a big lossy capacitor in the box? A sponge? We want to know.
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Nick Whitehead's profile photoRichard Murdey's profile photo
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+Nick Whitehead It does. Setting that aside for the moment, I just want to know what is in the box.
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RJM Audio

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Sony releases a new turntable. #mindblown
Sony is pursuing audiophiles, collectors, and connoisseurs with its new PS-HX500 turntable, a carefully crafted machine that hitches the company's "hi-res audio" wagon to comparatively ancient...
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Seems to be best buy product other than rega rp1
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RJM Audio

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Any more miniaturization and they'll barely quality as discrete op amps anymore.
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What I think is safe to assume is a clone of the Audio Technica AT-HA5000 headphone amplifier. This could provide some fun over the winter.
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RJM Audio

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The best-designed voltage regulator in the world is for nothing if power supply noise couples to the output signal directly.

That seems to be what's happening here. It's the current though the transformer secondaries which is inducing the noise I see. The shape of the noise pulse (spike up, spike down, 60 Hz cycle) shows the origin. I got careless and simply placed the transformers too close to the amplifier circuit.


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Separates, or a larger single case with the AC stuff well away from the amp and partitioned by a metal screen.
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How AKG K702 headphones are put together. Ignore the horrible narration, the video of the actual construction process is quite interesting.

(I have to replace the rubber loops on mine, so I need to have an idea of what to expect before I dive in...)
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Well written explanation of audio signal interconnects, particularly the difference between balanced an unbalanced and why with unbalanced (i.e. consumer RCA connections) you are basically screwed but relax because it works fine anyway.
Since the Audio Engineering Society has adopted the "pin 2 is hot" standard, what is the correct use for pin 1?
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OK let's do this.

*reads*

So... that was less instructive than I had hoped. Some interesting stuff about mutual capacitances and transformer shielding, but the take home is audio components won't be able to follow the rules outlined in the text due to the way signal cabling is handled. Oh well.
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This ASUS Xonar Essence STX replaces my Onkyo SE200-PCI. The line output buffer and I/V op amps are user replaceable. TI TPA6120A2 headphone amplifier is a bonus. BB 1792 DAC. ASUS controller. Requires 4 pin molex power. PCIe card, though the card architecture is PCI with a PCI-PCI bridge chip. Sounds as good as, or better than the Onkyo... and ASUS as put out working Windows 10 drivers!  http://bit.ly/1jfnwaD
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A resource for the design and construction of high-fidelity audio equipment.
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RJM Audio is my hi-fi hobby site. I design and build audio equipment, from interconnect cables to headphone amplifiers to voltage regulators though I'm best known for my VSPS and Phonoclone phono preamplifier circuits.
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