Discrete vs. Monolithic ICs
Why packing a circuit on a tiny silicon wafer limits acoustic performance, and how Vedom Audio's discrete design delivers pure, uncompromised audio amplification.
Physical and Electrical Limitations
An IC opamp is designed for low-cost manufacturing, whereby several hundred tiny components can be crammed onto one silicon chip. This reduces sound quality significantly. Not to mention that they utilize insane feedback loops within to achieve good numbers on paper, that demolish phase coherence and micro-detail.
- Silicon Diffusion Resistors: These resistors are formed inside the silicon wafer itself. They are characterized by their extremely high noise levels, poor tolerance (as much as 20%), and continual drift with temperature.
- Microscopic Non-Linear Capacitors: There is no room for large capacitors on a chip. Monolithic opamps feature microscopic silicon diode-capacitors, which are very non-linear and cause phase distortion.
- Thermal Coupling Problem: Since all stages are located on one silicon chip, the heat produced in the high-current output stage is immediately transferred to the sensitive input JFET stages and causes DC drift and thermal tracking distortion.
- Class-AB Bias: Monolithic chips are biased in Class AB to avoid thermal runaway. This results in crossover distortion precisely where it matters most – at the zero crossing of the audio waveform.
Absolute Freedom
Our discrete opamps feature independent, full-sized components which are mounted to their own gold plated four layer PCB. Meticulously chosen for supreme performance in both measurements and by ear. Combined with our state of the art design, we make no compromise for quality, space or cost.
- Precision Thin Film Resistors: We employ individual metal thin film resistors which have 0.1% tolerance and exhibit close to zero thermal drift and absolute stability, providing perfect channel matching.
- Ultra Stable C0G Ceramic Capacitors: Highly stable C0G (NP0) dielectric ceramic capacitors are utilized everywhere, including crucial signal paths. These caps provide zero voltage coefficient and phase linear response. Proper high end factory matched JFET's designed for audio on input, which is a story for itself, used to it's maximum potential on input stage.
- Thermal Isolation: High power output transistors are placed separately from input circuit so that input JFETs stay cool and stable.
- Commodity of heavy Class-A bias. All transistors are conducting at all times, making sure there is no crossover distortion, and in turn providing incredibly vast and open soundstage and natural warmth.
The Purity of Class-A Amplification
Monolithic ICs bias their output stages to turn off when current swaps directions, causing harsh distortion. Vedom Nova output stages remain constantly turned on.
Standard Class-AB (Monolithic ICs)
Transistors toggle on and off, creating harsh switching crossover noise at the zero-crossing.
Pure Class-A (Vedom Audio)
Continuous bias current flows. Transistors never shut off, offering perfect waveform continuity.
The Vedom Premium Component Stack
We select each passive and active device based on both measurement performance and acoustic listening tests.
Factory-matched audio JFETs
Our design incorporates extremely low-noise JFETs that are factory-matched onto one silicon die. As the two JFETs are practically the same and are thermally coupled, they have near-zero DC offset by nature.
There is no requirement for trimpots to be adjusted manually. They create mechanical contact noise and are extremely sensitive to any kind of vibrations and drift with temperature increase.
Ultra-Stable C0G / NP0 Capacitors
To ensure consistency, absolute signal integrity and cuircuit fine tuning, we employ premium C0G (NP0) ceramic capacitors. Unlike most commonly used x7r dielectric capacitors that generate undesirable phase shifting and distortion due to changing conditions, C0G dielectric capacitors have near-zero drift across temperature, voltage, and frequency.
0.1% Thin-Film Resistors
The 0.1% thin-film resistors are employed in our design due to their superior accuracy. These precision resistors have low thermal noise characteristics and a temperature coefficient <25 ppm/°C. Such an accurate matching is essential to maintain high common mode rejection ratio (CMRR) and gain balancing between channels.
Four Layer PCB
Our advanced four-layer PCBs are built using specific power planes. The particular stack up used in our circuit board guarantees that we have the least power delivery resistance and maximum current reserve capacity for active stages. Our power planes "make" parasitic capacitance between them a perfect capacitor with virtually zero ESR for HF decoupling, as well as providing small uninterrupted current loop area, when VAS swings high-speed transients, thus reducing EMI.