Squeexebox revisited
March 26 2010
(Also
see my first article from a year ago)
After succesful installation of my System
Asioka at home, I was very happy with the sound, especially that
the squeezebox duet bettered all my previous CD transports.
Two weeks later, an upgrade bug bit me again so I liooked for easy ways
to improve the Squeezebox.
Good product as it is, its achilles heel is power supply. So I
decided to take a good look at it first.
The wall wart which is supplied is DEFINITELY not a transformer based
supply. It is a cheap impulse supply and it looks suspicious already.
First -I looked at the input 9 V DC as supplied:
![](_MG_1046.JPG)
My photo above may be bad, but you can see what is going on. The
raw supply is ultra noisy. It contains a whole spectrum of spikes, some
of them almost 0,3 V deep.
![](_MG_1041.JPG)
Above - the same factory supply after I fitted some oscons on the main
Squeezebox PCB. The impulses got about 10 x smaller.
![](_MG_1044.JPG)
So I decided to build a PSU consisting of a 10 VA transformer for 9
VAC, a C-REG-C-L-C-L-C construction. It produces rock solid DC
without any funny stuff going on.
Here is the result (loaded with SQB, not idling.)
![](_MG_1039.JPG)
As you can see, it is as flat as flat goes. For me - it is flat
enough.
Finally I kept both solutions: oscons in PCB and good PSU.
I have built a box made of veneered MDF to accomodate the SQB and the
new power supply. Since SQB needs to communicate in WIFI - I could not
use a metal box. MDF is transparent for wifi.
![](_MG_1048.JPG)
Above: the main power input capacitor - it is inadequate both in size
as well as quality (ESR).
I decided not to replage but to keep it and ADD a better oscon in
parallel.
![](_MG_1047.JPG)
Here is how I soldered the incoming 9VDC - instead of using a wobbly
and noisy plug - I hardwired the SQB to the PSU.
![](_MG_1049.JPG)
Arrows poin to the pos and neg points for adding a bigger cap.
Make sure it is a low ESR type and bigger than 200 uF. I would like to
warn you about using the typical low ESR caps like teapo - because
these are usually only good for 6,3 V circuits, not 9.
The yellow-blue pair of wires is power supply. NOTHING gets
removed here.
![](_MG_1050.JPG)
Above: the output RCA jacks are snipped and floated.
Red circle shows a critical point where a good cap will feed the
voltage regulator which feeds the DAC chip. (a mod unnecessary if you
use SQB as a transport only.)
![](_MG_1052.JPG)
The hardwired supply of the DC is ready to work - I have burned a hole
in the box using the tip of my soldering iron.
The better (High-End ) power supply for the Squeezebox Duet as a
Transport (plus the Lampizator output stage).
![](_MG_1053.JPG)
Above: a test drive of the SQB and the power supply box. All works OK.
![](_MG_1055.JPG)
Above - the beautifully veneered box and SQB before installation
inside.
![](_MG_1056.JPG)
Above - all is finished. SQB is inside the new home.
K is the SQB PCB
H is high voltage anode supply for tubes
E is the transformer for lampizator
D is an array of caps for heater supply of the tubes (rectified but
unregulated).
F is the SQB sdupply first cap - 30 000 uF / 16 V
C is the SQB dedicated transformer - 9 VAC by 1 A by 10 VA
B is the lampizator - using two 6H6P in SRPP mode.
A is a pair of military PIO capacitors for tube output decoupling.
![](_MG_1057.JPG)
Above:
C is the main capacitor for SQB supply.
B is the pair of Roedestein caps after the 9 V regulator
A is the regulator 7809
J is the radiator
D is a fast cap 2,2 nF for bypass of electrolytes.
H is the second pair of Roedesteins
K is the earth bar
E and F are chokes between capacitors
(remember - the PSU is a noise free - C-REG-CLCLC)
G is an output oscon.
![](_MG_1058.JPG)
![](_MG_1059.JPG)
Above - the regulator from 9V to 5V for the DAC is now invisible under
the two blue oscons.
The cubic oscon is an SMD type, 10 uF / 10V installed AFTER the
regulator. The cyllindrical one is 220/10 installed BEFORE the
regulator. It is soldered in place of these two holes in the PCB .
Improving the SP/DIF output of the Squeezebox Duet Transport.
![](_MG_1061.JPG)
Last mod concerns the SPDIF output. I did not trust the tiny SMD parts
so I installed directly from the chip - the 220 nF cap (Vishay MKP
(marked D) and C is the series 200 Oh,m resistor and B is the
parallel 75 Ohm resistor (soldered to the GND - the frame of the RCA
socket.
I secured the cap by a blob of Soudal superfix glue.
The sounding of the upgraded Squeezebox Duet.
The result: the is definitely a better sleep and pride of achievement.
Via a transport SPDIF - I can detect beter sound quality but the
magnitude of change is small. I think that the scene is deeper and low
bass is deeper too.
The lampized Wolfson DAC chip is another story. It is not a Sabre
killer, but it is a very decent dac. I could live with it. It is clear,
dynamic, with great bass, I mean - it is so good that Iwould not use an
external dac at all if I was not so crazy about DACS.
Overall, as a transport only, the Squeezebox reading my HDD server -
sounds better than any transport I ever had. It even beats the modified
CEC. The sound is fresh, spectacular, fast, powerful - you name it.
There is something very right about that sound, Almost as if jitter was
non existent issue.
It has been now 3 weeks I havent touched a CD disc. I only use a
HDD. I am afraid - there is no going back.