[AuxInput]

Looking at my USB Audio Board - it looks like there is rectification being performed. Unless I am being naive here.

The black/red wires are coming from one of the two main transformers and just supply A/C at a lower voltage level. Yes, you are correct that there are rectification and voltage regulator on this card. This is essentially the power supply card for the USB input. The USB card should be mounted directly underneath this.

b0bb has had success in installing a separate small transformer for powering this USB board. I can't remember what specification he used. But you will need to wire that into the main power switch so that power gets switched on. I tested my USB input and I like the BNC coax input a lot better. However, I'm driving it from a crap motherboard. The JCAT USB card is on my future list.

I don't know how good this usb input is. I don't know if you want to spend a lot, but a USB interface might be a lot better. Options are the Singxer SU-6. Audio-gd has the DI-20 and DI-20HE, both which look excellent.

 

[DBX1]

The black/red wires are coming from one of the two main transformers and just supply A/C at a lower voltage level. Yes, you are correct that there are rectification and voltage regulator on this card. This is essentially the power supply card for the USB input. The USB card should be mounted directly underneath this.

b0bb has had success in installing a separate small transformer for powering this USB board. I can't remember what specification he used. But you will need to wire that into the main power switch so that power gets switched on. I tested my USB input and I like the BNC coax input a lot better. However, I'm driving it from a crap motherboard. The JCAT USB card is on my future list.

I don't know how good this usb input is. I don't know if you want to spend a lot, but a USB interface might be a lot better. Options are the Singxer SU-6. Audio-gd has the DI-20 and DI-20HE, both which look excellent.

Thanks AuxInput for the detailed explanation !!!

I can easily source a dedicated small torroid for dedicated USB Power inside this unit. I will have to think about how to add the torroids main AC input into the power switch.
I think I can well live with the inboard USB option it instead of going with another more expensive outboard USB option at this time.

I can tell you that the JCat Femto USB Card is a great card. They have a newer card that is about twice the cost.

 

[b0bb]

I've taken a picture of my USB Board. It is being powered by an umbilical cord coming direct from the power supply.

So in pursuit of elevating the sound on the USB input - the questions are:
is it still beneficial to purchase a separate power supply for the USB Audio Board ?
and if so, is it still necessary to get a rectification board from the power supply to the USB Audio Board (from ebay links as others have stated) ?

Looking at my USB Audio Board - it looks like there is rectification being performed. Unless I am being naive here.

Thanks everyone for any input that you offer !!!

Your board is already running on its own transformer winding, using a separate transformer only brings a small incremental improvement.

The weakest link is the power supply board.
The power supply on your USB card is one is based on the opamp running in an analog feedback loop.
The opamp is the OP177 with a closed loop bandwidth of 600kHz, this is pretty poor, the regulator stops being effective at about 300kHz.

Get the LT3042 supply in the ebay links posted previously, these things are effective to 10MHz +.
This is a better way to get the improvement.

In its current form the performance of the USB interface is very poor (utterly pathetic really) due to the poorly designed regulator board, leading more than a few 004 owners to use SPDIF.

Without modification the LT3042 regulator board will open up the soundstage and the vocals will gain an increase in presence
Bass becomes deeper, most importantly the board will work in native DSD512 without hiccups and dropouts.

The ebay seller I bought the additional board from said customers keep asking for it, it has been available on sale for almost 7 years.
This is very unusual as the Chinese vendors rapidly stop selling devices that do not meet the mark when there is a new version.
In this case most of the attempted replacements are history

The board can be further rebuilt to improve its performance, in that form it handily beat my SU-1 over I2S
This uses OSCON polymers on the input filter, vishay low voltage schottky diodes and a tantalum polymer for output bypassed by a MLCC cap and rubycon acrylic caps

 

[piaseczek]

I got an MH-DA004 recently and was just looking at some quick easy mods. I was thinking just copper shielding around the two PS, twist the 3 pairs of power wires going into the board from each PS, and maybe mount the PS on rubber or wood. Would that be a good start based on the photos I have attached?

Thanks.

It's a good start.
I've marked the next steps for you + Cystek replacement.
It's based on the b0bb's experience with the LKS 004 and 003. Thanks b0bb.

 

[piaseczek]

It's interesting that the DC bypass for the common mode DAC reference voltage in the 005 is changed to 0,1uF. In the 004 it is 10uF.

 

[piaseczek]

The hybrid polymer capacitors similar to the Nichicon FPCAPs are everywhere.

 

[gbickle]

It's a good start.
I've marked the next steps for you + Cystek replacement.
It's based on the b0bb's experience with the LKS 004 and 003. Thanks b0bb.

Thanks. I did the copper power supply shielding and twisting pairs and noticed a very subtle improvement so I will just leave it as it is now. Already have the upgraded USB power supply so I doubt I will get much more out of it with my system and hearing

 

[Whitigir]

Your board is already running on its own transformer winding, using a separate transformer only brings a small incremental improvement.

The weakest link is the power supply board.
The power supply on your USB card is one is based on the opamp running in an analog feedback loop.
The opamp is the OP177 with a closed loop bandwidth of 600kHz, this is pretty poor, the regulator stops being effective at about 300kHz.

Get the LT3042 supply in the ebay links posted previously, these things are effective to 10MHz +.
This is a better way to get the improvement.

In its current form the performance of the USB interface is very poor (utterly pathetic really) due to the poorly designed regulator board, leading more than a few 004 owners to use SPDIF.

Without modification the LT3042 regulator board will open up the soundstage and the vocals will gain an increase in presence
Bass becomes deeper, most importantly the board will work in native DSD512 without hiccups and dropouts.

The ebay seller I bought the additional board from said customers keep asking for it, it has been available on sale for almost 7 years.
This is very unusual as the Chinese vendors rapidly stop selling devices that do not meet the mark when there is a new version.
In this case most of the attempted replacements are history

The board can be further rebuilt to improve its performance, in that form it handily beat my SU-1 over I2S
This uses OSCON polymers on the input filter, vishay low voltage schottky diodes and a tantalum polymer for output bypassed by a MLCC cap and rubycon acrylic caps

I would love to know more about what you do to rebuild it

 

[LKDog]

Is this vendor for the LKS MH-DA004 legitimate?
This looks like the upgraded USB board version and it is a couple hundred less than other places.
Are there other charges like customs, etc in shipping to USA.??

LKS MH DA004 Ebay listing

 

[AuxInput]

There are a couple different sellers on ebay selling DA004. This may actually be the standard USB edition, as the same seller is also selling a "Amanero USB Flagship" version for $1549.

I bought mine from shenzhenaudio. Their current price is only $50-60 more than this ebay seller, so I wouldn't think the ebay offer is really that great. I have seen shenzhenaudio go on a 8% discount sale at times for the DA004.

 

[LKDog]

There are a couple different sellers on ebay selling DA004. This may actually be the standard USB edition, as the same seller is also selling a "Amanero USB Flagship" version for $1549.

I bought mine from shenzhenaudio. Their current price is only $50-60 more than this ebay seller, so I wouldn't think the ebay offer is really that great. I have seen shenzhenaudio go on a 8% discount sale at times for the DA004.

Thanks for the reply.

 

[piaseczek]

I would love to know more about what you do to rebuild it

here you will find the BOM made by b0bb:
https://www.head-fi.org/threads/lks-audio-mh-da003.745032/page-8#post-12035366

 

[piaseczek]

B0bb,
Could you tell if 5v for the amanero PSU is provided from the analog toroidal transformer?

 

[b0bb]

I would love to know more about what you do to rebuild it

Here is a before and after picture to highlight the changed components (C3,C4,C5,C6, PSU input filter C2,C8,C9,C10 and the 4 diodes)
USB socket changed out to something that gave more grip.
The shield on the replacement USB connector is a continuous piece of metal unlike the original which is made up of several pieces.
Kapton tape to insulate the socket from the chassis metalwork.

Before:

After:

C5 and C6 replaced by a parallel combo of a MLCC cap and Acrylic film plastic cap.
The caps are joined by brazing the solder to keep inductance as low as possible.

This is more complicated than the usual thru-hole cap swap, requiring fine control of temperature to prevent damage to the plastic cap.

 

[b0bb]

B0bb,
Could you tell if 5v for the amanero PSU is provided from the analog toroidal transformer?

On mine it is the transformer closest to the front panel, this powers the auxillary parts.
Do not use the analog side transformer, the USB interface will have a lot of noise from the board itself and that coming from the PC or host.
USB is on the dirty side of the isolation barrier.