Aleph J-X Amp Project

[CxTurbo]

That's what I was thinking also. Thanks for your input.

I was reading somewhere (one of the original X series threads I believe) that one of the XA series has around 480,000uF so I was going to aim for something in that ballpark.

James


James

[udailey]

Have you guys seen the quality of the MiniA power supply board from BrianGT on ChipAmp.com?
Its beautiful and hefty and cheap. 6 snap in caps, 4 diodes with placements for diode heatsinks, and room for inductors or resistors as well as on/off indicator LED. I use them for my chip amp but they are wonderful and you could wire up 2 of them for 12 caps if you wanted.
Uriah

[CxTurbo]

I'll Take a look. Thanks for the tip.

James

[udailey]

He unfortunately has no pics but I guarantee that for snap in caps and a max of 6 caps its about the best board I have seen. It will take radial leads of course. Max of 40mm diameter caps. Leads can be 10 or 23mm apart and 18mm apart if cap is offset towards outside of the board.
Black with Gold pads and white silkscreen.
They are about $9 each and just a great deal.
Uriah

edited lead spacing

[daddy4life85]

Those PSU boards are fantastic I have one laying around somewhere.... He used to have pics of them up.

[Coreyk78]

I got a second power supply board from Peter Daniel and added it to my Aleph-J so I am running 1 supply board per channel, 88000uF for each channel. I am using 2 50A/1000v bridge rectifiers and then splitting the DC from there to each PS board. I was hoping that somehow the extra capacitance would help bring up my rail voltage which is still sagging from an unloaded 25.2v down to ~22v with the amp boards connected. Is there anything I can change to get my voltage up? I'm concerned that running the voltage this low could have a negative effect on performance. This is with an Antek 600VA 18Vx2 transformer and my wall voltage is a steady 120v.

Also I tried hooking up my Zaph Audio BAMTM speakers to my Aleph-J last night which are 4 ohm speakers and the results were pretty poor. I was hearing some nasty distortion in music with a lot of bass. Is this because the amp was running out of current and clipping? That's why I'm concerned about the voltage. I didn't even have to turn it up very loud to reproduce it. I know that this amp isn't designed for 4 ohm speakers so maybe its just a bad idea to try using it with 4 ohm speakers at all.

[vdi_nenna]

Started a Wiki on the AJX. Please feel free to add or edit the Wiki.

[Melon Head]

Hi Coreyk
Are you using a crc powersupply?
For 4Ohms you need higher bias not higher voltage.
22V is still in the ball park. If it was below 20V then I might look at doing somethimg about it.

[Coreyk78]

Originally Posted by thanh1973

Hi Coreyk
Are you using a crc powersupply?
For 4Ohms you need higher bias not higher voltage.
22V is still in the ball park. If it was below 20V then I might look at doing somethimg about it.

Yes its CRC, 22kuF -> four .51r in parallel -> 22kuf

I used .51r resistors because digikey was out of stock on the .47r 3w panasonic metal films, only 0.01 ohm difference so I figured that was ok. I had some .47r vishay wirewound resistors but unfortunately the leads were too thick to fit through the board.

It was weird though, last night was the first time I tried running my BAMTM speakers with the Aleph-J, and I have just gotten done moving to a new house and hadn't played the speakers since I moved so I thought something might have happened to the crossovers in transit. Hooked up the MyrefC chipamp I have and they sounded perfect though. Then I hooked up a pair of Infinity bookshelf speakers to the Aleph-J and there was no distortion issue there either. Seems the two of them just don't get along.

[Melon Head]

3V drop seems to be what most people experience, so I wouldn't be to concerned about it.

For better performance into low impedance loads you could try changing R24 to 900 Ohms
or if you have the heatsinking you could add an extra output device to increase the bias.