[Forgisound]

The new Jinbo uncompromising machine, 005.
For double price.
But, I think, it is total high end.

 

[MartinWT]

Has anyone seen the LKS MH-DA005 yet? The layout looks beautiful.

https://shenzhenaudio.com/products/...ac-coaxial-opt-aes-ebu-flagship-audio-decoder

Oops, I see it has already been discussed.

 

[Xoverman]

Thanks B0bb,
last week i installed 220pf glass capacitors under the buffering elkos of the of the I/V stage.
Even though it didn't improve bass slam or level, it gives more clarity and depth, witch of course is always nice to have

 

[Xoverman]

As both B0bb and AuxInput point out, one of the biggest mods to the 004 is changing the I/V resistors .
Last weekend i had some time to exchange the factory 68,2 Ohm 0,5W resistors agenst Vishay CPF3 3-watt 61.9 ohm resistors.
After one day of burn in time, I gave it a first listening test.
I was very impressed with her performance !!! And this time bass performance improved dramatically.
( Grundton ) has become very well defined with more dynamics. Male voices are more mature or masculine, and female voices are softer and more real. All of the artificial glear is gone. Even tho I still use the silver mikas. I'm very very happy with the result.

 

[ESL57]

As both B0bb and AuxInput point out, one of the biggest mods to the 004 is changing the I/V resistors .
Last weekend i had some time to exchange the factory 68,2 Ohm 0,5W resistors agenst Vishay CPF3 3-watt 61.9 ohm resistors.
After one day of burn in time, I gave it a first listening test.
I was very impressed with her performance !!! And this time bass performance improved dramatically.
( Grundton ) has become very well defined with more dynamics. Male voices are more mature or masculine, and female voices are softer and more real. All of the artificial glear is gone. Even tho I still use the silver mikas. I'm very very happy with the result.

Thanks for sharing your tests and experiences, I take note for my next tasks to be done in the dac. By the way, did you choose the resistance value 61.9ohm because it was the one you found closest and with good characteristics of thermal stability ppm and precision, or was it for some different reason to lower and not raise the value? I have some components to change in my dac to try to solve the noise problem, if I succeed I will communicate it and explain it here. I would also like if someone could try to explain the function of each adjustable resistor and if someone knows a criteria and guidelines for each setting.

 

[ESL57]

Measuring DAC fullscale output current.
Method described below measures peak output current of the DAC which in-turn determines the wattage of the upgraded I/V resistor.

The method plays back a pre-generated fullscale sinewave signal thru the DAC.
The rms voltage across the I/V resistor is measured.

I have attached 0dB FS sinewave WAV files that can be played back on a MAC or PC

Steps
1) Plugin computer to the USB port on the 004
2) Select the Amanero audio device corresponding to the DAC and set it as the default
3) Set volume control on PC/MAC to the MAX
4) Set volume control on 004 to FIXED
5) Playback the attached WAV file (audiocheck.net_sin_1000Hz_0dBFS_10s.wav.zip)
6) Measure the AC voltage across the I/V resistor during the playback.

The red boxes indicate the position of the I/V resistors on the Gen1 board.


Multimeters costing less than 100USD may have problems accurately measuring the AC voltage at 1kHz.
I have included another test file with a 50Hz sinewave (wavTones.com.sin_50Hz_0dBFS_5s.wav.zip)

Take due care to avoid connecting headphones or speakers during this test if there is no volume control after the DAC.

Analysis and calculation
V: measured AC voltage across I/V resistor in Volts
R: I/V resistor value in ohms
I: Peak current output of DAC in Amps

I = (1.414 * V)/R

Resistor wattage is I * I * R.

Plugging in some real numbers.
On my Gen1 DAC

V = 3.14V
R = 68.1 ohm
I = 0.0652A (65.2mA)

Peak resistor dissipation is 0.289W.
The actual resistor should have 2X the rating given the poor ventilation in the 004, thus 0.6W or better.
I plan to use TX2575-2 (2 module Z-foil@0.4W) this reduces the cost by 30% from my original estimate.

Note:
These numbers are for my Gen1 DAC, the Gen2s have bigger heat sinks which suggests that LKS may have increased the peak output current.
The method described here will help answer the question as to whether LKS made any changes here.

I did not remember this interesting post, my heatsink is a small Gen1 version, not the big one, the current if low the value to 61.9ohm will increase to more than 70ma, I do not know if it will be a good idea or only the resistance will heat up a little more.

 

[b0bb]

I did not remember this interesting post, my heatsink is a small Gen1 version, not the big one, the current if low the value to 61.9ohm will increase to more than 70ma, I do not know if it will be a good idea or only the resistance will heat up a little more.

The operating current is programmed into the ES9038 at startup by its support microcontroller.

Changing the resistor value will not change the operating current, only the i/v transfer ratio.

 

[b0bb]

As both B0bb and AuxInput point out, one of the biggest mods to the 004 is changing the I/V resistors .
Last weekend i had some time to exchange the factory 68,2 Ohm 0,5W resistors agenst Vishay CPF3 3-watt 61.9 ohm resistors.
After one day of burn in time, I gave it a first listening test.
I was very impressed with her performance !!! And this time bass performance improved dramatically.
( Grundton ) has become very well defined with more dynamics. Male voices are more mature or masculine, and female voices are softer and more real. All of the artificial glear is gone. Even tho I still use the silver mikas. I'm very very happy with the result.

The 0.5W resistor used in some Gen2 units were undersized for the load current it had to carry.

 

[Xoverman]

Thanks for sharing your tests and experiences, I take note for my next tasks to be done in the dac. By the way, did you choose the resistance value 61.9ohm because it was the one you found closest and with good characteristics of thermal stability ppm and precision, or was it for some different reason to lower and not raise the value? I have some components to change in my dac to try to solve the noise problem, if I succeed I will communicate it and explain it here. I would also like if someone could try to explain the function of each adjustable resistor and if someone knows a criteria and guidelines for each setting.

The actual value of the resistor is not so critical, as long as you stay with in +/- 20% of the original value. So for example going from 68.2 to 61.9 gives me 0.5db lower output level, which of course can be ignored.
The potentiometers are there to adjust the the output offset. In my example the output offset had to be readrusted from -0,1 Volt back to 0,000 Volt after changing the resitors.

 

[b0bb]

The actual value of the resistor is not so critical, as long as you stay with in +/- 20% of the original value. So for example going from 68.2 to 61.9 gives me 0.5db lower output level, which of course can be ignored.
The potentiometers are there to adjust the the output offset. In my example the output offset had to be readrusted from -0,1 Volt back to 0,000 Volt after changing the resitors.

Please keep the replacement resistor as close to the stock I/V resistor as possible.
The SMD trimmer on the board has a very limited number of adjustment cycles, avoid readjustment as much as possible.

The I/V resistor in parallel with the I/V cap is responsible for the frequency compensation due to the input capacitance seen at the I/V input.

Not sure if the Gen2.x have different input capacitance, @AuxInput mentioned 220pf

Gen1 100pF//68.1ohm fc = 23.4MHz
Gen2 100pF/61.5ohm fc = 25.9MHz
Gen2.x 220pf//61.5 ohm fc = 11.8Mhz

 

[Xoverman]

Please keep the replacement resistor as close to the stock I/V resistor as possible.
The SMD trimmer on the board has a very limited number of adjustment cycles, avoid readjustment as much as possible.

The I/V resistor in parallel with the I/V cap is responsible for the frequency compensation due to the input capacitance seen at the I/V input.

Not sure if the Gen2.x have different input capacitance, @AuxInput mentioned 220pf

Gen1 100pF//68.1ohm fc = 23.4MHz
Gen2 100pF/61.5ohm fc = 25.9MHz
Gen2.x 220pf//61.5 ohm fc = 11.8Mhz

I had 68,1 Ohm and 2x 130pF opper side, and 1x 160pf next to the dual JFet soldered to the rear side. All three being silver mica.

 

[Gilberto 62]

Hi all. I haven't written here for a long time, but as always when I need a little light or advice, I turn to you who have experience and knowledge. Since I've achieved musical peace on my simple Foobar + iFi usb cable + LKS combo, I play all my music by upsampling to dsd512 and the IIR70K filter and setting the dpll to a minimum whenever possible. As I lack the knowledge to make those incredible upgrades that you see around here, my only option to have an alternative to this LKS, simply to have another device with which to compare, is another dac that you think is the same height than our mh-da004. Which will be...? RME, CHORD, another ...? I'm only interested in the dac function, which makes that conversion as sweet as possible. But please, not at John Rockefeller prices ... Thanks for your opinion.

 

[hygume]

Has anyone actually gotten their hands on a MH-DA005 yet? Modded 004 or a brand new 005.... Decisions, decisions.....

 

[Gilberto 62]

Has anyone actually gotten their hands on a MH-DA005 yet? Modded 004 or a brand new 005.... Decisions, decisions.....

Uh ...! That question interests me too. Anyone with the DA005 ...?

 

[AuxInput]

Not sure if the Gen2.x have different input capacitance, @AuxInput mentioned 220pf

Gen1 100pF//68.1ohm fc = 23.4MHz
Gen2 100pF/61.5ohm fc = 25.9MHz
Gen2.x 220pf//61.5 ohm fc = 11.8Mhz

I did not deviate much in the I/V section from my stock model, with the exception of bumping up the power supply filter caps (upgraded 22uf to 100uf). I had 61.8 ohm resistors and 220pf WIMA MKP's inside the I/V circuit. The 61.9 ohm Vishay VPF3 was the best and closest resistor I could find. The output compensation were 2200pf polyester (cheap). I did not have any silver mica in my Gen 2.x (as b0bb likes to call it).