Monday, May 17, 2010

Musical Fidelity Tubalog DAC (using valves - ***Update#2***)

I have several DAC(s) and am in the process of recapping these gems after many years of service.

This is about my only valve DAC, the Musical Fidelity Tubalog DAC. Some consider this model to be the best DAC from the British company.
With Sony CDP-333ESA as transport

From top with cover

I decided to get the grand old lady recapped since she was beginning to sound a bit tired e.g low volume, lack of details, did not sound like "being there".

MF used Torx screws with a rod in the middle to wart off "itchy fingers". Took a while before I was able to locate the correct screw driver to remove the lid to review the below. The pix was taken after I replace the 3 electrolytic caps on the board with the valves. The 3 caps were initially Panasonic FC. When I tested using stock Nichicon caps (with brown jacket), there was no noticable differences. Hence left the Nichicon in-place. The 2 large brown film caps on the same PCB as the valves were initially replaced by Wima's. Later the Wima's were replaced by Gad-Viva oil caps from Germany. The Gad-Viva's are worth every penny!

Original before recapping (except for Panasonic FC on buffer PCB)

PSU capacitors as these have to be less than 40mm in height.
After recapping

Bypass added to main PSU filter caps

During the recapping process, the sound of the DAC becames more involving and natural. I took the opportunity to replace a few "el-cheapo" parts along the signal path, especially in the audio sections- really opens up the unit!


After some great results using ERSE Pulse-X capacitors in my speaker project,  decided to substituite them into the Tubalog's output stage.

The result? As Gomer Pyle (shows my age) would say ... "G-o-l-l-y"!!!

Bass became firmer with clearity across the reproduction spectrum!!! Sounds superb thru my Meridian 201/557/A500 components


  1. SK Fong drop by to listen to the unit over the weekend. I think I can safely say he was mesmerize by the results after the recapping.

  2. WCK is you ah!!! oh.

    yes, yours a good set. agreed.

  3. friend,

    did i inform you i have bought the tubalog? am the 3rd owner of this DAC.

    yes, the Torx screws somehow is special type and i believe the 1st owner was inpatient and force opened the casing and destroyed it. now the top of my tubalog casing is missing of 2 screws and anyone can easily "flip" open it.

    how much for the 2x Gad-Viva cap? thinking to follow your spec to recap this DAC ;)

  4. Hi SK,

    Sorry to hear about the condition of the unit.

    Atleast it does not impact the sound reproduction capabilities of the unit.

    No worries, will SMS about when best we can take a look this weekend.

  5. What digital receiver chip does this DAC use please?

    1. Sorry the unit in storage at moment. Will update this post once I have opportunity to retrieve it

  6. Hi,
    1. gad-viva 2,2uf and 250v ? I dont find it.
    2. why do You remove c20 and c19 ? (top left corner)
    3. the rest of the capacitor values ​​as in the original?

    Thanks for help

    1. 1. Replaced Gad-Viva with Erse Audio caps
      2. Was like that when I bought it
      3. All original values except those stated

  7. Hi again, have You got service manual ? I changed capacitor and the sound is distorted. Please help me.

    1. No service manual found.

      You can always put back original capacitors one at a time to test if anyone of the newbies were bad.

      Best you inspect your changes to ensure no overlapping of soldering, loosen wiring or components, inadequate soldering, etc.

      Otherwise please take to repair facility for servicing.