Bel Canto DAC2 Mods

audioengr · « **on:** 23 Jun 2004, 02:47 am »

Finally, someone sent me a Bel Canto DAC2. Here are my initial listening reactions:

1) Not even remotely close to my reference modded P-3A DAC
2) Somewhat congested and lacking in depth of image
3) The usual lack of high-frequency dynamics
4) Does not have the magic "sparkle" of live music
5) Low-level annoying hum
6) Good bass response
7) Midrange sibilance with vocals - not edgy, but not natural either

Next Steps: open it up.. stay tuned

audioengr · « **Reply #1 on:** 24 Jun 2004, 11:42 pm »

Some things definitely done right in there, but others wrong, wrong, wrong....

Mods done to the following so far:

1) input pulse transformer added and impedance matched to 75 ohms - eliminated capacitive coupling - there was actually a 150 ohm matching resistor there. Does not make sense to me....
2) some transmission-line terminations adjusted
3) Nichicons replaced generic caps on power supply board
4) FRED's replaced rectifiers on power supply board
5) Post-DAC filtering caps upgraded
6) bulk decoupling caps changed from Nichicon Muse to Black Gates
7) high-frequency decoupling caps added to analog stages
8 ) Digital input RCA isolated from ground
9) more Black Gate bulk decoupling caps added

Audition results:

Very open and spacious now, with very good imaging and the hum is completely gone. Slam and HF dynamics are improved significantly. Still lacks a little in HF extension compared to the reference Turbomod P-3A DAC, but much more listenable. My wife described it as "dull" before the mods. I will ask her this evening to listen to the modded version.

There are some filters on the outputs - ferrites and SMT film caps may need to be removed next. Also planning new wiring harnesses from power board to DAC board. Must order parts for these. Also, it may need a Superclock2 to be on-par with the P-3A.

WEEZ · « **Reply #2 on:** 25 Jun 2004, 01:28 am »

I'm afraid to ask, but how much $ ?

audioengr · « **Reply #3 on:** 25 Jun 2004, 04:38 am »

Weez - I have not determined this yet, but it will be in the $600 range without Superclock2 or new wiring harnesses.

Listening tests with my wife this evening: She likes it better - not dull anymore, but she says piano is still slightly muffled. More changes tomorrow and modded Superclock2.

audioengr · « **Reply #4 on:** 27 Jun 2004, 11:18 pm »

Next stage mods - removed output filtering completely, ferrites and last stage caps.

Result: Now we are getting the percussion attack. Audience clapping is like firecrackers going off. Still some halos around the piano notes - probably due to clock jitter.

Final mods - install Superclock2 and new wiring harness.

Result: Superclock2 installed. The halos are mostly gone now. Focus and dynamics are first-rate. Sibilance is all but gone. Very good clarity. Very good HF extension too. The only difference between this and the Electro ECD-1 or the P-3A is the image depth, which is more shallow. I think the Analog Devices DAC chips and digital filtering in the Bel Canto give a little different presentation than the Crystal DAC chips. Time to put it on the website...

Parts for wiring harness still not here......

audioengr · « **Reply #5 on:** 3 Jul 2004, 04:33 pm »

Wiring harness parts arrived yesterday and I installed the harness.

The cymbols are much more clear now and the presentation more coherent. The soundstage depth improved as well. Still not up to the Electrocompaniet or the P-3A, but close. Sounds more like the P-3A now, but the piano notes are a bit more rounded. It's up on the website now.