Classic and transformer coupling: System grounding difference

The use of signal coupling transformers requires a somewhat different approach to the system grounding.

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Another story about TDA1541A: 384 kHz

Can this old gem get there?

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Back to the roots: 14 bits (of TDA1541A)

By measuring standard low level performance at -60 dBFS (dithered sine wave), there was practically no difference between its regular 16 bit, and this 14 bit “mode” of operation. Noise floor, on the other hand, is somewhat higher, roughly speaking 6-12 dB, and that is what you would expect, given 2 bits difference.

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Transformer coupling pros and cons (in a nutshell)

Purely sonically, transformer coupled output has more calm presentation, with more quiet background, and somewhat more precise soundstage. On the other hand, transformers can lack some definition at the most bottom end. Still, possible benefits and shortcomings depend also on the environment.

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Cermet potentiometers

Audial Model A uses cermet potentiometer as premium part. The reason is simple: cermet is sonically clearly superior to any other potentiometer type. Cermet potentiometers are still however relatively unknown, so more information follows.

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Model A volume control

Model A uses the low impedance shunt potentiometer. This article brings more details about this ultimate volume control.

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Model A, one year later: Binding posts

Model A now sports copper plated copper binding posts. Here is why.

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Sweet spot of amplifier power

According to the common wisdom, the relation between the amplifier power and its sound quality may look like the relation of equivalence. “The more the better.” The truth is, the best sound quality is associated with certain working points, which also implies certain power. Insisting on (often redundant) power, actually can and does compromise the sonic properties.

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Designing the ultimate monolithic amplifier

A sum up of more than decade of designing and living with chip based power amplifiers.

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Sound of harmonic distortion

Harmonic distortion is one of the basic and most common ways to objectify sound quality of audio device. Yet, there is no consensus on its audibility. Here are several examples of distorted sinewave, to help your own understanding.

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Data and signal: are we progressing?

Are bits still just bits? Actually, notable part of improvements achieved in the digital audio in last two decades happened due to designing for higher signal integrity criteria. So not that much for instance in the area of converter chips, which were during this time developed mostly to lower production costs. As a result, even if Philips D/A chips from 80′s are in many areas still unsurpassed, today it would be unimaginable for any serious design to repeat layout or clocking schemes as they were done in Philips CD players from 80′s (or majority of players from that time, for that matter).

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PSU transformers, part 2: Model S USB inside

As a follow up to the previous article on transformers, here is how this part is done in the Model S USB. This is also the first public appearance of Model S USB interior.

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PSU transformers: EI vs. toroidal, and more

A couple of most important points on mains transformers differences. Some of these probably counteract to what you have learnt on this topic before but, as one fellow audio enthusiast wrote in the early days of the internet (when internet was young and pure), “most things we could learn about hi-fi were simply wrong anyway”. Food for thought.

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TDA1541A and Model S USB, part 4: TDA1541A grades and series

Audial DACs are famous for using all quality parts, and not one or two for marketing purposes. Still, is S1 (single crown) really better than plain TDA1541A (or non –A), and is S2 (double crown) then better than S1?

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TDA1541A and Model S USB, part 3: TDA1541A today

It is important to understand that TDA1541(A) wasn’t one simple point in DAC chips history, but the end and crown of its own era, in which DAC chips did not perform any kind of processing.

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TDA1541A and Model S USB, part 2: Simultaneous data mode

In the Model S USB, TDA1541A operates in simultaneous data mode, and this is why Model S USB is practically free of data related jitter artifacts.

Model S USB is the only DAC with TDA1541A operating in simultaneous data mode.

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TDA1541A and Model S USB, part 1: 192 kHz?

Tthe Model S USB uses TDA1541A and it is up to 192 kHz compatible device. It means that it does not downsample, neither inside the DAC nor at PC side, but it just converts any 44.1/48/88.2/96/176.4/192 kHz file directly, at its native frequency.

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Asynchronous USB

As opposed to the S/PDIF, USB is a bidirectional protocol that makes possible to make peripheral device (here the D /A converter) act as a master device, and PC as a slave that delivers the data only when and as requested by the DAC. This way, the overall clock performance at the DAC is not related to and limited by the quality of PLL used, or by PC. It is solely determined by the quality of free running oscillator, placed locally in the DAC. Such a solution became lately known as an “asynchronous USB”.

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