Aleph-X PCB

svemir · 26th March 2007, 06:10 PM

I have drawn aleph X PCB and I am wondering is it ok? Does it have any mistakes or some bad solutions in the layout!

Schem is taken from: http://www.kk-pcb.com/alephx.html
And here is the layout:

svemir · 26th March 2007, 06:14 PM

And here is Scheme with component markings!

sk_tuner · 2nd April 2007, 06:03 AM

my mail is sk.tuner@gmail.com
contact me please, i like your pcb project

carpenter · 2nd April 2007, 07:14 AM

Are you mounting your power FETs on the pcb? If not, be sure to locate the gate resistor at the FET, and not on the pcb.

svemir · 2nd April 2007, 07:49 AM

Mosfets are going on the PCB board, thanks for the advace obout Gate resistors but i am allready familiar with that.

Francis_Vaughan · 4th April 2007, 07:22 AM

Nice layout really. My only criticism is really one that is hard to avoid without a double sided board. The attached pic says it all.

carpenter · 4th April 2007, 07:59 AM

Hi Francis,

I'm not following your idea very well. Care to elaborate further? It seems you're drawing electrical loops, but I can't see what's causing them.

The Aleph X is a balanced circuit, so I assumed that electrons flowed evenly from the negative rail towards the positive. Come to think of it, the left and right portions of the pcb could be 180 degrees out of phase (+ and - input and amplification signals). Is this what causes the loops?

John

Francis_Vaughan · 4th April 2007, 09:47 AM

Essentially what I'm trying to show is that as the current is steered about you get changes in the flow though the legs. The run across the middle is the speaker load. What I have drawn is an inaccurate extreme (I was too lazy to depict the remaining current in the active load legs - which is still very large). What it is, is an attempt to depict the dynamic current changes. Mirror image it for the other phase of the input cycle.

What you might get is the output coupling back into the circuitry in the middle of the board - especially if there are any reasonably large area loops.

Ugh, I just realised there is a no-no in there too. The drain resistors of the LTP go to different points on the -ve rail. That rail is going to see currents modulated by the signal on the two sides - just as I drew. The voltage drop (and there will be one even across a few cm of track) will leave a signal dependant voltage between the two halves. This is unlikely to help their tracking. They need a private trace between them, which is then connected top the -ve rail at one point only.

svemir · 4th April 2007, 10:59 AM

Like this.
Should I remove R20/R19 and R36/R35 so they are not on the pcb and put them directly on the Gnd of the power suply central point.

Francis_Vaughan · 4th April 2007, 11:44 AM

Yup. That was what I meant.

The principle is important in general. People worry about star grounds, but forget that any other high current leg with any modulation on it has exactly the same problems - and pretty much the same solution.

2nd April 2007, 06:03 AM	#3
sk_tuner diyAudio Member Join Date: Dec 2005 Location: sisak	my mail is sk.tuner@gmail.com contact me please, i like your pcb project __________________ sign. free

2nd April 2007, 07:14 AM	#4
carpenter Paper mache horn fabricator diyAudio Member Join Date: Mar 2002 Location: Oregon City, Oregon	Are you mounting your power FETs on the pcb? If not, be sure to locate the gate resistor at the FET, and not on the pcb. __________________ I enjoy audio so much that I constructed a web site. I share my ideas at: www.inlowsound.com

4th April 2007, 07:59 AM	#7
carpenter Paper mache horn fabricator diyAudio Member Join Date: Mar 2002 Location: Oregon City, Oregon	Hi Francis, I'm not following your idea very well. Care to elaborate further? It seems you're drawing electrical loops, but I can't see what's causing them. The Aleph X is a balanced circuit, so I assumed that electrons flowed evenly from the negative rail towards the positive. Come to think of it, the left and right portions of the pcb could be 180 degrees out of phase (+ and - input and amplification signals). Is this what causes the loops? John __________________ I enjoy audio so much that I constructed a web site. I share my ideas at: www.inlowsound.com

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2nd April 2007, 07:49 AM	#5
svemir diyAudio Member Join Date: Dec 2005 Location: zagreb	Mosfets are going on the PCB board, thanks for the advace obout Gate resistors but i am allready familiar with that.

4th April 2007, 09:47 AM	#8
Francis_Vaughan diyAudio Member Join Date: Feb 2005 Location: Adelaide	Essentially what I'm trying to show is that as the current is steered about you get changes in the flow though the legs. The run across the middle is the speaker load. What I have drawn is an inaccurate extreme (I was too lazy to depict the remaining current in the active load legs - which is still very large). What it is, is an attempt to depict the dynamic current changes. Mirror image it for the other phase of the input cycle. What you might get is the output coupling back into the circuitry in the middle of the board - especially if there are any reasonably large area loops. Ugh, I just realised there is a no-no in there too. The drain resistors of the LTP go to different points on the -ve rail. That rail is going to see currents modulated by the signal on the two sides - just as I drew. The voltage drop (and there will be one even across a few cm of track) will leave a signal dependant voltage between the two halves. This is unlikely to help their tracking. They need a private trace between them, which is then connected top the -ve rail at one point only.

4th April 2007, 11:44 AM	#10
Francis_Vaughan diyAudio Member Join Date: Feb 2005 Location: Adelaide	Yup. That was what I meant. The principle is important in general. People worry about star grounds, but forget that any other high current leg with any modulation on it has exactly the same problems - and pretty much the same solution.

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