Monday, October 25, 2010

One step further: Piotr's 405-project

Piotr, from Poland, revised his 405 with the Dada-kit ... and some other components:

He wrote:


-Dada Electronics basic revision kit on OPA604,
-mains voltage selector removed,
-double power supply with common zero (chasis),
-8x10000uf/63V BHC power supply capacitors,
-WBT speaker terminals,
-Cardas Rhodium RCA sockets,
-Furutech pure copper ICE socket,
-3N silver, gold plated wire for most power supply connections (plait),
-new rear panel, moved backwards to fit in with lots of capacitors,
-Cardas 3%Ag solder used,
-all PCB pins shortened and resoldered,
-Ultralink Challenger 2 signal cable (6N OFC),
-C1 caps removed (short),
-abandoned PCB fuses .
-1,2V input sensitivity

General philosophies:

-Minimum connections - zero connections except primary fuse, PS capacities, and ground to case screws.

-Power supply wiring made of silver wire is constant, uncut, unsoldered, no connectors, handmade plait - from "source" to "target" (rectifiers to PCBs passing capacitors, case to speaker's zeros, all zeros passing one crossing)

I didn't meet any serious problems. Almost didn't test the unit before run. Started from the first time. Results are stunning. Believe me. No partial distortions. Perfect, stereophonic, focused sound. Pleasant and reach at the same time. Pure black background with natural, creamy recording's noise. Much more agressive, faster, precise but still natural, rich, transparent sound to live with. Bass not foggy. Similar bass shape and depth like before but this is not coffee with milk anymore. This is more like.. dark brown, thick espresso that you can feel, but you cannot touch.



Anonymous Anonymous said...

OOOps! Maybe that's nice to look at.... BUT:
all these stiff and straight cables from chassis/transformer to the PCBs (especially this short arm-thick input-cable -- pure horror!). This will have but one effect: The PCB-copper-pads will suffer from mechanical stress!! Hence there is a big risk of mid-term failure -- and absolutely no (sonic) improvement in sight!
If you cannot resist this kind of short-cable-cosmetics (but it would be better and cheaper to resist it!): Give some room for flexiblility (by s-shaped or rectangular ways). So it does not harm - at least.


4:03 PM  
Anonymous Anonymous said...

The reason it sounds different is not down to all the exotic cabling and connectors, but you've shorted C1 and totally screwed up the the LF response!

Take a look at Bernd's mod's and do something worthwhile to your amp.

6:12 PM  
Anonymous Anonymous said...

I wonder how long the transfo will last. With 80.000µF I can imagine the peak current...

9:29 PM  
Anonymous Anonymous said...

@Anonymous the LF response of a 405 has nothing to do with C1, it is determined at 12dB/octave by C4/R6 and C2/R4. But I agree with you about the grossly excessive capacitance across the PSU. Some people seem to have never heard of conduction angle ... or the law of diminishing returns.

9:43 AM  

Post a Comment

<< Home