A new Aleph3 is born...

[Smithers]

Hi everyone,
now i have finished my first DIY-Amp, an Aleph3..
I am very pleased with the results, the sound is simply marvellous! Here are some details
500 VA 2x18V transformer, 6x47000uF Caps bypased with Wima MKP10 1uF, Mcap Supreme (induciotnfree) 0.1uF and a 10nF KP (an addvice from Klaus, i am still testing..), Epcos 5Ohm NTC for limiting inrush current, MBR3060PT double diodes, mounted on an 2 K/W heatsink, two Fisher SK56 heatsinks (0.35K/W), the enclosure is made of 3mm (about 1/8") copper. The amp weights 18kG (about 40 lb) The front is made of 16mm (3/5") MDF wood with Madrona-veneer. The amp has got a Dc-offset of 20mV resp 30mV on the other channel. The heatsinks get to a temperature of 55 degrees (room-temp is about 23 degrees).
Oh, I don´t have acces to my webspace right now, so i have to attach the pics as a zip-file...
regards,
smithers

[Smithers]

Here is the zip file..

[Taco]

Very Nice,

One question, your power-supply is for both channels? (1 transformer, 1 bridge, 1 bank of caps)

The answer is yes (You posted the pictures te same time as my reply )

[Smithers]

Oh, i forgot the PCB ;-)

Here it is:

[JDeV]

Originally posted by Smithers
......, 6x47000uF Caps bypased with Wima MKP10 1uF, Mcap Supreme (induciotnfree) 0.1uF and a 10nF .....

1. Does all this bypassing really help and what does it actually do ?
2. Why 3 differant values?
3. What type of caps works best for this purpose?

[Smithers]

Originally posted by JDeV


1. Does all this bypassing really help and what does it actually do ?
2. Why 3 differant values?
3. What type of caps works best for this purpose?

Hi,
i just made a copy of the cascade that Klaus is using in his Aleph4, have a look:
Small Aleph 4 power block...

I haven`t yet tried other values or other combinations myself so i am not able to verify his observations at the moment, i am still testing,but i suppose that everyone has to make his own tests to find out what type of cascade fits to his amp best.
Regards,
smithers

[Miles Teg]

I've got a problem.
I've horrible difficulties to get some thermistances in France.
I don't want to try my aleph3 without it.
So we have the CL-60 and the Epcos 5Ohm NTC.
Do you know some other parts for this work?

[JDeV]

You can get thermistors in any PC powersupply, they aint always 5ohm - some 12 or 15ohm, but still work just as well. I use 2 of these in serie on my Aleph30, from 0volt to earth ground and another 1 just after my AC line fuse and it works perfect, every time. Just take note that they do get warm when passing current, so if you switch off, wait for it to 1st cool down before switching on again, other wise fuse will go pop.

[JDeV]

Originally posted by Miles Teg
I don't want to try my aleph3 without it.

Something else, you can also fit a 3.5amp slowblow fuse in the meantime, all this is just to give inrushcurrent time to settle, no other major reason, well - yes you must have a fuse for overall protection.

[Miles Teg]

Other thing else. Because my English isn't very well , I believe to read somewhere that the inrush current can break parts beside the PSU, like the IRF. But I don't think so because I can't explain that.

So your advice is to put a slow blow fuse in remplacement of the thermistor. Just a temp solution of course.