Pleiades K951 single N channel MOSFET zero feedback audio power amplifier in class A1

At your risk. Take all safety precautions. A suitable fuse must be in serries with any battery for injury or fire hazard protection.

Today the 2SK951 MOSFET was placed on the big heatsink.

Vb=12V. Output transformer bifilar 1:1 with air gap.

Signal path:

music on CD - SONY D-EJ758CK CD Walkman line out - Pleiades K951 - Marantz Imperial 5-G

It sounded not loud, and when the 1K pot was near maximum the sound started to fade out.

Fortunately before abandoning, on a quick decisive move the Wago connector was opened and the signal was sent bypassing the volume pot directly to the gate terminal through the 560K Philips orange coupling capacitor.

Sound became big and loud indicating a broken potentiometer.

The amplifier sounds very nice with deep bass and extended treble, smooth midrange. Some overload at peaks as the full signal is feeding the gate without attenuation.

Id is 500mA at Vd 12V. So power dissipation 6W. Possible power output 3 Watts?

It seems a suitable MOSFET can do the trick without the need of a step up input transformer.

But the electron tube Pleiades DL94 seems to sound better.

Thanks to Vasilis encouragement the Pleiades single transistor amplifier experiments were not abandoned

At your risk.

After so many failed experiments today the power is ten times what it was last year. About 3 Watts? 

So according to S.S. Stevens law loudness is double.

 

Humans Are Idiots and I Am a Very Good Specimen

 

Can diabetes be prevented or even reversed by eating whole grain food instead of products made with white flour, sweeteners etc

 

At your risk.

This is not a medical or nutritionist advice.

For example by eating whole grain tahini?

Advantages of Electron Tubes (Electronic Valves), (Vacuum Tubes) in audio amplifiers

 At your risk.

1. They are cute.

2. Some of them can glow nicely in the dark, orange or blue.

3. They are small size and low mass as no big and heavy heatsink is needed for an amplifier operating in class A (electrons flowing all the time)

4. They are very low noise. So low noise that you don't hear any hiss on Sinatra voice recorded with a Telefunken U47 microphone having a VF14 electron tube inside it. The noise performance of a whole system is dictated by the first stage. Also Harry Olson chose an electron tube instead of a JFET on his experiment on measuring  the thermal agitation noise of molecules with a ribbon microphone inside an evacuated chamber.

5. They sound great. We know that for more than a hundred years.

6. Triodes are so far the most linear electronic amplifying devices without any feedback or its side effects.

7. They are perhaps the most compact and easy way to experiment with electrons themselves and what they can do in a small glass evacuated envelope.

8. They do not need air blowing fans. They radiate heat effectively as the anode can be at a very high temperature without destruction of the device.

9. They cannot be so small that we can place millions of them in a small area and then wonder why do we waste energy.

10 They have high output impedance forcing us to use an output transformer, possibly the greatest sounding and most linear passive device ever made. Dozens of microphone, console, reel to reel tape recorder, signal transformers on our favorite sounding records.

11 They teach us to be careful with electricity which can be dangerous. For example by applying the military practice of one hand inside the back pocket so that touching circuits with both hands in avoided.

12 They teach us to be careful in handling electronic devices.

13 They can amplify straight line frequency response from DC to Megahertz and much more as they have small input capacitance and no heatsink which can be a high output capacitance.

14 They can operate at very high but also at very small voltage if the inherent negative grid bias by the electron cloud near the cathode is compensated by a few Megohms resistor from low voltage anode to grid.

The Pleiades single Darlington BD650 power amplifier in class A supplied by 12V sounds very nice

 At your risk.

Update to Pleiades IRFS450 zero feedback single ended power amplifier with air gap output transformer

 At your risk.

Today a freshly charged 1.2Ah 12V battery was connected. Still using the 1:1 output transformer.

Playing the song Blue Velvet the sound was not impressive. As if the amp has reduced gain at small signals and increased gain at large ones. Is this because the operating point is at a current less than 500mA?

Back to the Pleiades single Darlington BD650 with approximately 3:1 output transformer the sound is phenomenally better with so deep bass, bandwidth.