Aleph J illustrated build guide

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Blk Dynamite

Member
Joined 2016
pggriff said:
Getting near the end of my Aleph J project, it’s my first amplifier and has been a great learning experience, thanks everyone for all of your posts! Question on wiring both balanced and rca inputs in single chassis. I have some 6 conductor wire that is shielded and sports an uninsulated ground wire. I was going to run one wire each from +v rca and xlr terminating each to +v input on board, same with -v . Now I’m not sure if I should use the bare shield wire connected to the ground on the xlr and terminate on the chassis or use one of the other insulated wires in the package. From my reading here grounding is very important with respect to noise elimination, perhaps I should keep it simple and just use some standard wire. Does anyone see an advantage to the insulated cable?
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I'm a noob to all this but I wouldn't ground that wire to the chassis. I think the XLR should be grounded to the board and such there should be only one grounded spot on the base plate that has the Cl60. I grounded mine on the board and its dead silent. In any event the masters will correct us both.....
 
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pggriff

Member
Joined 2014
Blk Dynamite said:
I'm a noob to all this but I wouldn't ground that wire to the chassis. I think the XLR should be grounded to the board and such there should be only one grounded spot on the base plate that has the Cl60. I grounded mine on the board and its dead silent. In any event the masters will correct us both.....
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I'm inclined to do as you've done Blk Dynamite, dead silent works for me.
 
nikko03

nikko03

Member
Joined 2009
Hi
I just started to build the Aleph J. Right now i work on the psu.
I have a question. I am shure it is answered in this tread. But i was lacy and hope someone would answer here so i dont have to search the whole tread :)
with 2*18vac inn to the psu. What should i measure between v+v- and between gnd v+ and v- I really hope someone can answer me :) :)
 
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gary s

Member
Joined 2002
With a measured 18VAC on your transformer secondary and a suitable PSU with no load and capacitance value as required for a class A amp, you will measure +25VDC to ground and -25VDC to ground. If your incoming AC mains supply voltage to the transformer primary winding is high, then you might read up to 27VDC unloaded on the PSU. This voltage will drop under load and depending on the transformer regulation percentage ratio and the VA rating of the transformer.
 
nikko03

nikko03

Member
Joined 2009
gary s said:
With a measured 18VAC on your transformer secondary and a suitable PSU with no load and capacitance value as required for a class A amp, you will measure +25VDC to ground and -25VDC to ground. If your incoming AC mains supply voltage to the transformer primary winding is high, then you might read up to 27VDC unloaded on the PSU. This voltage will drop under load and depending on the transformer regulation percentage ratio and the VA rating of the transformer.
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Thank you for reply. So it is near correct when i measure 24vdc from v+ and v- to gnd and i measure 48vdc between v+ and v- then :)
 
D

DSMStudio

Member
Joined 2016
I'm trying to finish up my first build and have run into a problem. Everything is assembled and I am measuring +25.5 dcv and +25.5 dcv leaving the PCU. I am not able to get the Mosfets on either the right or left channel to heat up.

The source resistors are measuring 0v . the voltage across R8 is around 8.43 volts, I'm assuming that since the voltage to the amp board is ok, that is where the problem lies. It also then appears that I made the same mistake on each amp board but I can't figure out what that was. I am new to this and can't figure out the schematic enough to figure out where to start looking.:confused:

I've attached a poor photo and will take some better ones later if needed.
 

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JSA1971

JSA1971

Member
Joined 2016
Paid Member
DSMStudio said:
I'm trying to finish up my first build and have run into a problem. Everything is assembled and I am measuring +25.5 dcv and +25.5 dcv leaving the PCU. I am not able to get the Mosfets on either the right or left channel to heat up.

The source resistors are measuring 0v . the voltage across R8 is around 8.43 volts, I'm assuming that since the voltage to the amp board is ok, that is where the problem lies. It also then appears that I made the same mistake on each amp board but I can't figure out what that was. I am new to this and can't figure out the schematic enough to figure out where to start looking.:confused:

I've attached a poor photo and will take some better ones later if needed.
Click to expand...

Have you pre-set the bias pot as per the build guide? Also, what value resistor is that for R8? Should be 1kohm, looks like 100 from pic. A few of the solder joints look like they should be redone.
 
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