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Cheap hi-end system - version 3
by Andrea Ciuffoli - started in the April 2010

INTRODUCTION

This born to create a cheap and good complete system with hi-end sonic performances superior to many commercial medium and high price systems.
 

Some characteristics:

COMPONENTS

AMPLIFIER

The previous cheap systems use the the Gainclone amplifier with LM3875 chip but here to get a more neutral sound and more power my choice is a nxV200 VFET-MOSFET Audio Amplifier Module.

There are many testimonials to support the good sound of these modules.

The main specifications of these modules are:

  • 110 Watts RMS continuous sine wave into 8 Ω 
180 Watts RMS continuous sine wave into 4 Ω 
The HPA-nxV200 is 2 Ω Stable 
Biased into Class A/B 
Power Bandwidth 3.5hz to 600khz -3dB
Small Signal Bandwith 3.5hz to 3.5mhz
Slew Rate = 80v / microsec approximately 
Dampening Factor At 100hz  8Ω = 800 
RCA Single ended Input impedance 33kΩ 
Single Ended Input Gain = 30.6dB 
THD+N - Typically 0.005%
Toshiba MOSFET Output Stage

For both, amplifier and dac, I have used the HI-FI2000 GX388 metal box (310 x 280 x 80mm) got in the Audiokit shop.

To create the heat sink has been used one side of the HI-FI2000 1PD02300B ask as single part and split in two parts.

The power supply is composed by a r-core transformer  37-0-37V with 600VA, a FWB1 rectifier module with Schottky Full Wave Bridge Rectifier got by Avondale Audio and 2 x 22000uf 63V Keindeil capacitors.

If you don't find a r-core you can use the good Nuvotem Talema Encapsulated Toroidal transformers from RS-Components.

In all my projects I am using a DACT stepper attenuator instead of the normal Alps or Noble solution, but in this case, with a limited budget i have used a blue Alps 10k+10k buy at Audiokit webshop.

The nxV200 modules does not have a fet input stage so it is necessary insert a capacitor after the Alps and I have used a Black Gate electrolityc 10uF 16v (negative pole on module input terminal).   

To get the best sound bypass both the 22000uF Keindeil capacitors with a 22uF MKP Solen or SCR.

As bypass to the 22000uF I have tested also ELNA Cerafine and lower value MKP but the best result is only with 22uF MKP.

The sonic differences using the 22uF MKP bypass are very big so I suggest to use always these.

The power supply switch is a 15A got from RS Components cod. RS Stock No. 665-679 by APEM.

To create the interconnect cables I have used:
   4 x Tasker SP60 for the custom analog cables
   2 x Tasker SP59 for the custom digital cable
   4 x Loudspeakers connectors BPF 105 red & black
   2 x RCF 230 TF red chassis Female RCA
   3 x RCF 230 TF black chassis Female RCA
   2m Tinned wire pvc insulated Farnell cod. 117-2904
   3m Coax cable Tasker T40 75ohm (digital)

Many of these parts are available in the Audiokit shop.
     

DAC

Follow this link to see the complete project and ask for the pcb of DAC end 2 to Quang Hao

The amplifier will follows the sound of this true hi-end DAC given a top level result.

My choice about power supply transformers has been:

LS70-1 0-15X2(0.8A) 0-12X1(0.8A)  about 23.5$
R80-55 0-9 X2 (3A),0-250(200mA)    about 45$

got on Ebay shop DIY-Gene.
To reduce the distortion, to increase the output level and to load better the 10Kohm ALPS I have decided to use a E182CC Mullard with the Kand Audio modules to implement a current generator instead of normal anodic resistors.

The amplification factor of the E182CC is 24 and with the 5687 is only 17-18.

 

 
As output capacitors I have used a 2.2uF Solen or SCR and a 1uF Obbligato Copper Case Aluminum Film.

1uF in parallel to 2.2uF = 3.2uF

This mean a lower frequency cut off on 10Kohm ALPS at:

Ft(-3dB) = 1 / (2 * 3.14 * C * R) = 1 / ( 2 * 3.14 * 3.E-6 * 10Kohm) = 5Hz

 
The two good heat sinks in the I/V power supply are Farnell cod.  1710611  5,6°C/W for the filaments and cod. 1710612  4,4°C/W for the anodic.
   
The two main chips, CS8414 and AD1865, are available in many Ebay shop but keep attention to the fakes.
Solder the CS8414 on a SOIC (SMD) to DIP adapter could be not very easy so buy a kit.

For both, amplifier and dac, I have used the HI-FI2000 GX388 metal box (310 x 280 x 80mm) got in the Audiokit shop.
 

LOUDSPEAKERS

Any 2 or 3 way loudspeakers in the range of 2000-3000$

 

CD PLAYER or CD TRANSPORT

I have some found problems with the CDROM used like cd transport because with some CDs there are blocks of the controller or high noise coming from transport.

The unique CD player for Hi-end DIY is the CDPRO2M  from: www.diy-high-end.com

An valid alternative could be any low cost CD Player or better a cheaper DVD/DIVX Player with a spdif coax output.

 

USB TO SPDIF

This USB to Spdif converter has been created using the Kit/2 only 49$ got from http://www.hagtech.com/hagusb.html and a 5v rele' to add an automatic switch of digital sources.