Interesting elaboration from Trinity Audio CEO Dietmar at AE:
Enclosed a measurement result, which is related to the stereo mode you use at the moment in HK. It shows the THD of a half-bridge (one stereo channel) module driving a 1Ohm load. Just one note, that is the technical limit of my current audio analyser and not of the power amp module.
The sweep goes from 0.1Vrms – 7Vrms, which is related to a maximum output voltage of 40V peak to peak. That means the amp drives +/-20A peak currents into this load and as you can see the output signal is distortion free. The maximum power is 194Wrms or 400W peak and the measurement frequency is 200Hz.
You all know I do not claim values on a paper, I show the real measurement results and I am sure you will hear and enjoy it.
One point, the amp was actually not designed as stereo amp. I implemented this stereo mode only for PT and his high efficiency 96dB horn speakers. A Magico Q5 with its very low sensitivity should be used with two mono blocks. A Alexandria XLF with almost 93dB can be used with a stereo block, but with two mono blocks you will get much more head room.
The TRINITY PA has more gain stages in parallel since the PHONO, therefore the noise coming from the active electronic is even lower than from the PHONO. I need more gain stages to get more headroom to drive higher voltages. The lower noise was not the main target, but it comes for free in this design. In this case the source resistance of the power amp determines the overall noise of the amp. The input impedance of power amp is 20kOhms, which is the main source of the noise. That is the part where the TRINITY Preamp comes in, the output of the preamp is a double terminated balanced Radio Frequency Pi-Attenuator based on a 600Ohm design. That means if you use a TRINITY Preamp as driving source the power amp see only 600Ohms (0.44µV noise voltage) instead of its own 20kOhms (2.5µV noise voltage) and this 600Ohms does not change over the selected volume or frequency. I have shown on a graph below that my gain stages can drive even 80pp distortion free into heavy 600Ohms. 🙂
By the way I know you all do not like the small form factor of my designs, but honestly it is a high frequency amplifier with a power bandwidth of 700kHz, the is no way to make it bigger. Bigger means longer signal paths, which adds a reactive load in the feedback, since all the 84 output transistor pairs per half bridge must be driven. The heart of the design is a special 8-layer PCB with extra thick copper traces. I had to extract the PCB parasitic and put them into the simulation to get these outstanding results. That is a technique is a must in very High Frequency designs.
God bless I have worked in the last 30years in all fields of electronic design. So I consider myself more or less as a “mental decathlete” than a pure audio designer.
Audiophile Regards Dietmar