[dacusb]

Hi B0bb,
 
Thank you for your help and guidance so far.
As per your recommendations, can I mod by:
1)Replacing the I/V resistors with Vishay TX-2575 Z-Foil  Metal foil resistors, and leaving the existing Wima caps as they are, unchanged?
 
2) Replacing the bypass cap by using the  Tantalum bead cap as shown in the picture ?
 
3)Replacing the V_com trimpot with a Vishay Accutrim metal foil trimmer?
 
dacusb

 

[b0bb]

  Hi B0bb,
 
Thank you for your help and guidance so far.
As per your recommendations, can I mod by:
1)Replacing the I/V resistors with Vishay TX-2575 Z-Foil  Metal foil resistors, and leaving the existing Wima caps as they are, unchanged?
 
2) Replacing the bypass cap by using the  Tantalum bead cap as shown in the picture ?
 
3)Replacing the V_com trimpot with a Vishay Accutrim metal foil trimmer?
 
dacusb

These can come after the simpler mods
1) 100MHz Crystek CCHD-950X XO
2) Sonic Imagery Ticha 994 discrete opamp for the I/V
3) Self powered enhanced USB interface with the Crystek CCHD-957 XOs from LKS/Volent

 

[dacusb]

Dear B0bb,
 
Actually I have been following-up quietly all your posts since the beginning of 2016 and I have done many mods accordingly incl. 100MHz Crystek CCHD-950X XO, replacing the existing IV opamp to Ticha 994, swapping the unbalance opamp to Muses01 etc...
As I use the Singxer SU-1 USB interface to connect to the LKS using both AES and HDMI/I2S ports, hence I do not touch to the USB part of the LKS.
It is time to think of some further mods, but to tell the truth I am very reluctant to replace the Wima caps. Will it be OK if I bypass the Wima caps while only replacing the I/V resistors with Vishay TX-2575 Z-Foil Metal foil resistors?
Thank you for your prompt feedback.

 

[b0bb]

  It is time to think of some further mods, but to tell the truth I am very reluctant to replace the Wima caps. Will it be OK if I bypass the Wima caps while only replacing the I/V resistors with Vishay TX-2575 Z-Foil Metal foil resistors?
 

The Vishay Z-foils are relatively easy to add, to go beyond this other components on the board will need replacing

 

[dacusb]

 
8pcs of the following. The 63V ones are smaller but Mouser does not have those in stock.
http://www.mouser.vn/ProductDetail/WIMA/MKP2D031501H00KC00/?qs=sGAEpiMZZMv1cc3ydrPrF2Av7JKdyW4DCABnugoea9E%3d
 
NOTE:The existing 0.1uF MKS caps need to be removed, these are next to the Black Panasonic FM caps. On mine the place is re-used by a 100pF Corning CGW glass cap, the square black box.

 
 
You will need a desoldering iron for removal of the stock caps , solder braid is not recommended due to the large risk of damaging the board.
 
I mount mine under the board
 

Hi B0bb,
 
I have noticed that you have mentioned that the place used for 0.1uF MKS caps is re-used by a 100pF Corning CGW glass cap, the square black box. Can you indicate whether it is necessary to install the 100pF Corning CGW glass cap at this place? If it is, where acn I get the Corning CGW glass cap?
Many thanks B0bb.

 

[b0bb]

Originally Posted by dacusb /img/forum/go_quote.gif
where acn I get the Corning CGW glass cap?

Ebay http://www.ebay.com/itm/262657134111.
 
Normally these are 30-60USD each, the 120pF is close enough.

 

[Dionis]

Hello, I'm from Ukraine.
B0bb, I admire the work done by you work to improve the LKS Audio MH-DA003 DAC.
I read the whole thread of this forum, and I have a question that I have not found an answer. I use return only unbalanced output, I set OPA301b amplifiers. To improve the sound to me necessarily to replace operational amplifiers in balanced outputs on Model 994Enh-Ticha Dual Discrete Op Amp.
For me it is large enough costs $ 200, and whether it will be worth this investment. Or maybe leave standard OPA1612, in the balanced output.

 

[Dionis]

B0bb, and the second question to you, generally correspond to OPA301b their characteristics for signal amplification in class A in unbalanced outputs. Here are the detailed characteristics of the op amp http://www.ebay.com/itm/1X-OPA301-MK2-DUAL-AUDIOFEEL-DISCRETE-OP-AMP-Board-Low-Impedance-/282005506216
Thank you in advance!

 

[b0bb]

  I read the whole thread of this forum, and I have a question that I have not found an answer. I use return only unbalanced output, I set OPA301b amplifiers. To improve the sound to me necessarily to replace operational amplifiers in balanced outputs on Model 994Enh-Ticha Dual Discrete Op Amp.
For me it is large enough costs $ 200, and whether it will be worth this investment. Or maybe leave standard OPA1612, in the balanced output.

The 994 is used in the current-voltage converter and is common to both the balanced and unbalanced stage.

 

[b0bb]

  B0bb, and the second question to you, generally correspond to OPA301b their characteristics for signal amplification in class A in unbalanced outputs. Here are the detailed characteristics of the op amp http://www.ebay.com/itm/1X-OPA301-MK2-DUAL-AUDIOFEEL-DISCRETE-OP-AMP-Board-Low-Impedance-/282005506216
Thank you in advance!

Looks OK for use in the unbalanced stage.

 

[Dionis]

message from b0bb /img/forum/go_quote.gif
  Looks OK for use in the unbalanced stage.

B0bb, I can not properly asked. If I only use the unbalanced output, whether the effect will be on the replacement of the operational amplifiers in a balanced stage (I / V). Or for unbalanced output has an effect on the sound quality is only the operating uilitel.

 

[b0bb]

  B0bb, I can not properly asked. If I only use the unbalanced output, whether the effect will be on the replacement of the operational amplifiers in a balanced stage (I / V). Or for unbalanced output has an effect on the sound quality is only the operating uilitel.

LKS converts the balanced output (U2/U3) to unbalanced to provide the unbalanced output.
Below is the reference analog stage for the 9018, the unbalanced converter section (U1) is slightly different on the LKS.

 
The Ticha 994 is used for U2 and U3.

 

[penguin69]

Hi b0bb
 
I am currently running the LKS in balanced mode, on the rationale that removing a set of op amps from the signal path means one less potential distortion source. The sound is very good indeed. It also helps a little in that my passive preamp seems to have been designed for lower outputs than that provided by the unbalanced output.
 
I have one question: does the LKS analogue stage architecture expect current draw from the output stage op amps? I have removed these, on the perhaps simplistic presumption that they are not needed.
 
Thanks in advance.
 
(ps - my LKS mods will continue shortly, I've just been held up recently with work and a vacation.)

 

[b0bb]

 
I have one question: does the LKS analogue stage architecture expect current draw from the output stage op amps? I have removed these, on the perhaps simplistic presumption that they are not needed.
 

 The unbalanced output stage in the stock LKS opamps draws a negligible current on its input, the replacement Burson opamps you are using is expected likewise.
 
Drawing a load current from the I/V converter (U2 and U3) will compromise its performance, this is the reason for the large 1k resistors which isolates the load from the I/V converter, the reference 9018 output stage has an output impedance of around 4k which is quite high (aka drives long cable runs poorly)
 
The XLR output should only be used with active preamps, I use a Schiit Mjolnir which has no problem driving 25ft Canare Star quad XLR cables.

 

[fjc36]

LKS Audio MH-DA003 has model mkII now, that use DAC ES 9028 Pro, any idea of its sonic performance would be? The main clock is still to be the Crystek 82 fs, (575? )that was first thing replaced by 950 here. It is on the market now and the price is rising to RMB 8000. Seems no alteration of the front appearance.