Monday, May 17, 2010

Sansui AU-9900A (***Updated***)

The Sansui AU-9900A is one of all time favourite units. It is know as the AU-10000 in Japan. You can view many details pixs of the unit at the AMP8 (Japanese) site.

Unknown to many Sansui fans, the 9900A is one of the rare Class-A units produced by Sansui. I managed to locate the service manual which confirms via 50mV setting via adjustment of the trimmers on the main driver board.

I was not aware of the above until I  managed to get a unit from eBay and paid for postage from the US. I initially though I bought a faulty unit when it was running warm and then hot!!! Had to get a dedicated fan to suck the hot air out before the exterior of the units was reasonable to touch!!! Unfortunately the fan is a little noisy ... (need to obtain a less noisy fan)

This is the pix under the covers.
You can see the original capacitors (some deformed) on the PSU board below. Please be aware of the bi-polar caps on the power board.

This is the original pre-amp driver board. Before re-cap, you could heard some raw-ness in the reproduction, especially on the high frequences.
Original pre-amp board
Pre-amp board after re-cap

The original AU9900A sounded so good I sold my AU-20000 (and kept the 9900A). The AU20000 was considered by many to be the top of the line integrated amp from Sansui!!!

The following is the pix of the main driver board after it was recapped. Took the opportunity to swap out some cheaper parts with better quality ones.

Audiolab 8000DAC (###Updated###)

The British made Audiolab 8000DAC is well loved for it's warm and natural sound.

DAC and CDM playing CD recorded with EQ
According to various documentation on the net, the Philips TDA1547 is the heart of the unit - not able to see the actual chip as hidden by the Audiolab cover on the motherboard (see below).

Decided to recapped the unit a while back (before creating this blog) as it was taking atleast an hour to warm up and sound decent. Volume before the recapping was very low as well - really sounded tired.

Took the opportunity to do some part replacements along the way as the unit had a treble and bass roll-off when I was listening to it using my Accuphase and Meridians (later on those).

Anyway, the pix below is the resultant of my efforts.

I am using the 8000DAC with the 8000CDM (black tray), 8000T and 8000A (all true Brits). Such 8000A's were the last of the true Audiolabs with "F" in the S/N (aka before sold to TagMcLaren).

From top
From bottom

And I added a few heatsinks to the power regulators to reduce heat levels as well. In addition, two silver mica's were added as by-pass to the non-EC capacitors.

View the blog for my Audiolab 8000A at to see and hear how the units perform together.


Recapped the EC in the PLL control section of the DAC located at the bottom LHS of the unit - 4*100uf 35V and a 47uF 16V, as the power supply filter to the LM317 could be better. Now working fine again.

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