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Old 26th May 2011, 12:27 PM   #3681
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Hi luxury54,

Quote:
if it's possible for you to attach a basic schematic of this concept for testing purposes I'm sure many of us will appreciate it, ... ONLY if this is possible
No problem, I attached concept schematics.

Schematics shows a basic rectifier, C1 provides some mains RF attenuation.

The actual common-mode capacitance multiplier consists of two ripple reduction circuits / capacitance multipliers, one in the plus and one in the minus rail. It provides over 500,000 times ripple and interference attenuation. So with typical 100mVpp input ripple, output ripple would be approx. 200nVpp.

Separate transformers or windings are required for multiple voltages as there is no longer a common GND path starting at the smoothing cap.

Multiple voltages are achieved by connecting +V or -V terminals of multiple regulators. Each power supply could be viewed as a "floating" battery power supply.

I currently use discrete voltage regulators based on bipolar transistors, or the more refined FET regulator shown in the schematic.

The FET regulator consists of a cascoded CCS based on 2 JFETs. Series regulation is done using a MOSFET series transistor. L1 serves as voltage reference, the current through L1 depends on JFET CCS properties. JFET T6 compares reference voltage with attenuated output voltage and controls MOSFET T3 gate.

I use 4 of these regulators in the SD-player, one for the SD-transport and 3 more for DAC power supplies.
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Old 26th May 2011, 03:22 PM   #3682
fff0 is offline fff0  Singapore
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Noob question: does this concept schematics work without exploding/ problem? If so, I will give a try.
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Old 28th May 2011, 10:08 AM   #3683
ryanj is offline ryanj  Australia
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Hi John

Just been looking over the regulator schematics, is the role of T4 and T5, along with the resistors to attenuate the spike in positive flow after T3 starts conducting?
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Old 29th May 2011, 09:14 AM   #3684
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Hi fffo,

Quote:
does this concept schematics work without exploding/ problem? If so, I will give a try.
Yes, well except if you reverse polarity of C2.

Tip, when experimenting with circuits, connect them through an energy monitor that displays circuit power consumption. Add a mains (safety) switch between monitor and circuit. If power consumption exceeds expected levels, mains can be switched-off instantly before problems occur or circuits get damaged.

It usually takes some time for a reverse connected electrolytic cap to heat up and finally explode or vent, or a power transistor to heat up and short out. During this time the energy monitor would display unusual high power consumption.

Increased transformer hum (core saturation) can also be a warning sign that something is wrong.
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Old 29th May 2011, 09:16 AM   #3685
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Hi ryanj,

Quote:
is the role of T4 and T5, along with the resistors to attenuate the spike in positive flow after T3 starts conducting?
T4, T5, R3, and R4 form a cascoded constant current source. Cascoded constant current sources offer much more stable output current and higher impedance.

This constant current runs through T6 and voltage reference L1 (1.6V). T6 (JFET) can be viewed as a variable (voltage controlled) resistor. When resistance varies, and current is kept constant, the voltage across T6 will vary. This varying voltage is then used to control MOSFET T3.

The refinement over a bipolar transistor based regulator is that gate currents are virtually zero, so they don't change while the circuit is keeping the output voltage constant. This means that the full cascoded current source output current has to flow through L1, all the time, regardless of correction voltage on the gate of series regulator T3. Also, voltage divider R5 / R6 can't dump current into L1 because gate current of T6 is virtually zero.

T4, T5, and T6 are low noise FETs, this helps to achieve low noise DC output voltage.

With the earlier version based on bipolar transistors, the LED reference current would vary slightly caused by varying transistor base currents. The output voltage divider would also dump extra current into L1 through b-e junction of the connected transistor. This leads to reduced output voltage stability with varying input voltages and / or load currents.
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Old 29th May 2011, 09:59 AM   #3686
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Are you using 2sk170 GR BL or V class?
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Old 29th May 2011, 03:15 PM   #3687
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Hi marconi118,

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Are you using 2sk170 GR BL or V class?
I am using 2SK170-BL for the positive FET regulators and 2SJ74-BL for the negative.
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Old 29th May 2011, 04:59 PM   #3688
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please post the negative regulator schematics
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Old 1st June 2011, 12:04 PM   #3689
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Hi marconi118,

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please post the negative regulator schematics
Negative regulator schematics are attached.
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Old 3rd June 2011, 02:33 PM   #3690
ryanj is offline ryanj  Australia
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Hi Everyone

Just been doing some comparison between over-sampling and NOS; and i came across this at lessloss audio, which john refered me to coincidently.

A minimalist design such as the use of no upsampling or oversampling yields the best sound. The industry needs to return to the roots of simple design. Some companies are doing this and they achieve better results that way.


LessLoss made extensive test devices which allowed the comparison of several filtering techniques including the now ever popular non-filtering solution. The method chosen for production is to implement the following oversampling: 8x oversampling at 44.1 and 48 kHz = 352.8 and 384 kHz; 4x oversampling at 88.2 and 96 kHz = 352.8 and 384 kHz; 4x oversampling at 176.4 and 192 kHz = 705.6 and 768 kHz.


Imaging is better, soundstage is more defined, there is less distortion of subtleties in the music signal, and you hear a reproduction which is unrivalled by all non-oversampling solutions.


In my own opinion, with NOS sound is somehow more natural, and sound stage is deeper, higher, and wider. Even without IS2 attenuation.

Yes, i admit that NOS without IS2 attenuation, highs are somewhat dirty and inaccurate, but still i think id prefer it than oversampling, which produces a sound that is smeared or smoothed out in some way.

I just cant see how Lessloss can think that sound stage and imaging is more accurate with oversampling?

Maybe they know something we dont. (John excluded)

Just wanted to give me 2 cents, so to speak.

What do you think John?


Ryan
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