DIY 300 Watt MOSFET Real HI-FI Power Amplifier..

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This is from the website,which i will provide by PM'ing me ,because I'm not sure if i can post it . "I am committed to sharing my experience of the RAS 300 with other enthusiasts sharing my passion for perfection.I designed this minimalist amplifier to be durable, simple to operate while offering high fidelity equivalent to the original sound source and would recommend partnering this amplifier only with other products of outstanding quality.

When I set out to design this amplifier, my aim was to create a product most suitable for the reproduction of complex music and speech signals. Although I placed high emphasis on electrical characteristics, the single most important requirement is achieving an audibly superior sound, vivid spatial imaging and superb tonal clarity.

Although the average listening level is normally less than 10 watts, my design approach was to create an amplifier with ample reserve power, but biasing it for class A at average listening levels reducing cross-over distortion to extremely low levels.

There is not one capacitor in the signal path, improved the accuracy of the tonal characteristics of instruments and voices significantly.
The RAS 300 has almost zero phase distortion far beyond the audio range resulting in perfect resolution and totally un-coloured sound.

Amplifier Specification:
Maximum Output: 240 watts rms into 8 Ohms, 380 watts rms into 4 Ohms
Audio Frequency Linearity: 20 Hz – 20 kHz (+0, -0.2 dB)
Closed Loop Gain: 32 dB
Hum and Noise: -90 dB (input short circuit)
Output Offset Voltage: Less than 13 mV (input short circuit)
Phase Linearity: Less than 13 0 (10 Hz – 20 kHz)
Harmonic Distortion: Less than 0.007% at rated power
IM Distortion: Less than .009% at maximum power

The amplifier consists of two completely separate monaural amplifiers each channel has its own power supply, resulting in zero inter-channel cross talk, a common phenomenon in amplifiers sharing the same power supply.

In order to obtain the full output power each supply transformer should be rated at 40VAC – 0 – 40VAC at 640VA. Unlike many designs relying on the reservoir capacitors to supply peak currents, I prefer to have the raw power available from the transformer resulting in much faster transients.

Although the RAS 300 specifications are moderate, when listening to it you will immediately experience the massive reserve power available and never have any cause of anxiety that something is going to give in that one would when driving many amplifiers loud.

You will hear nothing but reality with no distortion at any level and I guarantee that this amplifier will divulge the best qualities of any equipment connected to it.
Project Files
 
Hmm, sounds interresting! I like that its separate power supplies on each channel. You could then just duplicate the individual channels for however many you want.
 
Just be careful with the claims. If it is the same RAS300 that has been making rounds for years there are some serious design flaws inherently killing all the beautiful promises. To get anything like 300W you need more output device pairs. He claims 380W rms into 4 Ohms. Now a quick calculation shows that that means delivering peak voltages of +/- 55V, equal to his rail voltage without any drop across the transistors! These voltages require nearly 14A of current, but each transistor is only good for 8A maximum, taking them very close to saturation, and giving a vast voltage drop.

This circuit is simply incapable of delivering anything like the performance he claims, and will probably just blow the BD139/B140 up the first time a big signal arrives.
 
Originally Posted By: Y_K
Just be careful with the claims. If it is the same RAS300 that has been making rounds for years there are some serious design flaws inherently killing all the beautiful promises. To get anything like 300W you need more output device pairs. He claims 380W rms into 4 Ohms. Now a quick calculation shows that that means delivering peak voltages of +/- 55V, equal to his rail voltage without any drop across the transistors! These voltages require nearly 14A of current, but each transistor is only good for 8A maximum, taking them very close to saturation, and giving a vast voltage drop.

This circuit is simply incapable of delivering anything like the performance he claims, and will probably just blow the BD139/B140 up the first time a big signal arrives.


I did some quick googling earlier, after my first post, and came across the same thread I believe.
 
I have some Hitach mosfet built in a vintage Hitachi integrated - I hear they are sought after devices. I bypass the pre and go into the amp direct and its a good sounding amp. You typ really only need high curent with Magnepans and Big Theils and electrostats with passive subs. With all the EFI/RFI around now you may WANT/NEED a tranny or cap or some other FR filter circuit in the input.
 
Yes, that is a Hitachi design "ported" buy a gent from South Africa about 20 years ago, and the consequent "porting" with corrections, improvements and adaptations (e.g. some solid state elements are not made any longer) forked the project quite considerably. There are a few highly sought after among affordable ones: a Kyocera 900 (A), JVC X9 (Super A), old Sony, Yamahas, Marantzes and what-not from the Golden Age of true Hi-Fi of the 1970s. For some mysterious reason audiophool industry moved to New Zealand since..
That stuff is more addictive than motor oil in my case. My garage set is comprised of a Vandersteen 2Ce pair hooked to a vintage set of separates with its own roof antenna feeder. And then every room has something nicer. My only Tv is a small 13" Sony monitor though.
 
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