Tuesday, 10 December 2013

"AmpliSettembre" 100W Power Amplifier with Regulated Supply for VAS stage and BJT as output devices

Power Amplifier AB class named "AmpliSettembre", classic scheme using BJT as Power Output Devices.
Voltage rails of VAS and Input Stage are regulated in series mode.

"AmpliSettembre" 100W Power Project

Tuesday, 22 October 2013

Mosfet Amplifier 100W Example Schematic: AB class Principle Diagram

The Following Schematic is an Example about Easy Implementation of Mosfet Power Amplifier.
Power Supply is not regulated.
AB class operating.
100W could be obtained in 8ohm load.
Mosfet 2SK1058 2SJ162.Mosfet Amplifier Example Schematic

Mosfet Amplifier Schematic Example

Dowload PDF schematic document:

Friday, 18 October 2013

QUAD 405 Vintage Current Dumping Amplifier 100W My DIY Project

This is my "remake" of first, legendary, Current Dumping Amplifier : QUAD 405.
This is one mix, my personal mix, of  his varius  release, Quad 405 I , Quad 405 II etc.

My DiY Amplifier QUAD 405

I made a stereo version with prototipe in year 2007.
Replacement components:

IC1: TLE2071 OpAmp
TR9-TR10: MJ15003

You can download pdf format below.

Electric Scheme: 

Quad 405 DIY
My personal Quad 405 DIY schematic diagram

PCB Layers:
My Quad 405 layout
Quad 405 components placement

Dowload PDF schematic of my project Quad 405 :

Download PDF PCB plane of my project Quad 405:

Friday, 4 October 2013



No Fault!!! 

Every component is OK, power BJT are OK!!

So I put new main chord and give power.
Both channel have some volts of offset in their output and the idle current is too low.

So, following the Service Manual I can set the correct value of bias and offset trimmers.

Next step is to change the DISC lamp

VR1-VR2: offset voltage setting trimmer
Yamaha A-1

Saturday, 28 September 2013


Not working Amplifier, Yamaha A-1 all Black metal.
I'm almost sure it is broken or it has big trouble because the main cable is cut.

Yamaha A-1
So I start, open the case.....wath I find is...Dust

Dust inside..

I remove dust from jewel...

Yamaha A-1 inside, without dust!!
Inside A-1 demonstrate his particular design, Two Power Transformers and two big capacitors.
Power amplifer circuit is splitted on 2 boards+1 an 2 Big Heat Sinks.

The input and VAS stage is a full of components board, there is also an other little board(+1) only for to mount  the Yamaha double n channel JFET 2SK100

Yamaha 2SK100  Y-K100 JFET

Next Step: let's find trouble!!!

Friday, 14 June 2013

DIY Headphone Hybrid Amplifier Schematic Simulation

To semplify last project I choose to exchange Current Generator by a simple Resistor.
Power dissipate is about 4W so this component, 60ohm, shoul be composed by 2x120ohm/5W resistors.

Semplified schematic

Distortion increase, third harmonic

Distiortion increase, Vin=1Vpk, Vout=5Vpk but the power on the Haedphone is 400mW near the maximun power admitted, 500mW.

At 3Vpk out:

3Vpk output

Friday, 7 June 2013

Hybrid Headphones Amplifier Project, ECL82 (6BM8) plus Power BJT for 32ohm Philips Fidelio X1 With Tube Distortion

I'm looking for an Amplifier to drive my new 32 ohm impedence Philips Fidelio X1 Headphones.

My personal project is illustrated below:
Static Voltages
I would have a tipical Tube Distortion, I choose ECL/PCL to drive a Big BJT witjout other BJT drivers, not only 2SC3281, maybe I'll use 2SC2337 I bought from GB but potential fake....
Q3 should be change by 2 diode 1N4148 with related R25 value.
The amplifier factor should be not high, here is 5, there is no overall negative feedback.
Below the Simulation of distortion with V2(Vin)=1Vpk, V(R6)(Vout)=5Vpk F=1kHz

Second armoni c distortion for: V2(Vin)=1Vpk, V(R6)(Vout)=5Vpk F=1kHz

Static Currents

HeadPhones Amplifier Bandwidth

I hope I'll make it soon...

Thursday, 30 May 2013

Sony DTC-1000ES Digital Audio Tape DAT with Sony CX20018 ADC and Philips TDA1541A DAC inside

Sony DTC-1000ES DAT Player

Not Working, but very beautifull Player!
Elna Audiograde Capacitors.
Philips TDA1541A - SAA7220P/B Chipset for DAC
Sony CX20018 for ADC

Sony CX20018 ADC 

Philips TDA1541A

To restore and repair.....

Tuesday, 14 May 2013

HTA: Hitachi Top Mosfet Amplifier 100W Project Using 2SK1058 2SJ162

 Hitachi Top Mosfet Amplifier Project

All Semiconductors, BJT - Mosfet.
Only Schematic.

Download Mosfet Amplifier Schematic pdf

HTA: Hitachi Top Amplifier
B Class Mosfet Power Amplifier, using Hitachi's Mosfets 2SK1058-2SJ162.
Input differential stage and VAS stage are like Sony's ES 90's  amplifer.
VAS is Cascode Configuration.
Output Stage use 4 devices, 2 N channel MOS and 2 P channel MOS, note the power voltage rail is NOT regulated, the signal voltage should be... anyway they must be separated.

100W Continuos Power into 8 ohm could be obtained with appropriate Power Supply

Hitachi's Mosfet Amplifier Project 

My Personal GY50 Hybrid Amplifier 50W 8 ohm

My Personal Copy of Famous Aloia Hibrid Amplifier GY50. Amplificatore GY50 .

Amplifier using Vacuum Tube, ECC83/12AX7, for VAS Stage and Triple Stage of Emitter Follower in the Output Power Stage.
Power Output Devices; Toshiba 2SC3281 2SA1302.
All Regulated Power Supply.
No Overall Negative Feedback.
50W/8ohm, THD<1%
Made by Altium Design / Protel  CAD Database

Regulated Power Supply of  Power Stage

Output Power Stage Triple Emitter Follower

Vacuum Tube VAS Stage

Vacuum Tube Power Supply 

Amplifier and Power Supply  PCB , Printed Circuit Boards:

Power Output Stage, Output devices 2SC3281-2SA1302

Signal VAS Prited Circuit Board 12AX7/ECC83

Signal Stage Power Supply

Current Buffer Regulated Power Supply