Aleph-X : adjustment details

[GlouBou]

Hello There,

I have just finished my first Aleph-X and I would like to adjust it.

Is anybody can explain it to me in detail : I'am a poor lonesome newbee

Here is a picture of my amp front :



and inside



In fact I need a step by step procedure.

Lot of thanks

Kind regards

@+ GlouBou

[Netlist]

Congrats with this very nice looking chassis.
Do have a look at the WIKI, the adjustment procedure is explained in detail over there. If anything might not be perfectly clear, tell us.

/Hugo

[GlouBou]

Hello,

Thank you for your answer.

I read the wiki page for Aleph-X. There are some informations... but no procedure. I repeat : I'am a complete newbie. I do not have knowledge about that sort of things. For some of you on this board it's perhaps stupid questions, but my gaol is to learn.
This is also a way for other newbies to learn.

Here is what I would know :

4.7.1 - Adjusting the Variable Constant Current Source

How can I have an sinwave about 60 Hz ?
How do I input it in the amplifier ?
I read that is for res12 and res34. I use Hifizen part list and thoses res are fixed (1.2K)

Other things

How may I use VR1, VR2 and VR3 ? What are there role ?

Where must I mesure (exacte place on PCB) ?

Is there particular things to do ? Plug some power res in the output ? Connecting some device on the input ? Connecting loudspeaker ?

Is there some other things ?

Thank You

@+ GlouBou

[Netlist]

A sine wave comes from a signal generator.
If you don’t have the hardware you can download a software version http://heliso.tripod.com/download/generator/dsg.htm .

Connect the output of your soundcard to the input of the amplifier. Start with low amplitude, that is measured with an AC voltmeter something like 100mV. 60 to 100 Hz or so will do.
On Hifizen’s schematic, replace R12/R34 with variable resistors. 1.5k will do.
Then follow the Aleph current source adjustment described in the Wiki.

From Grey in the original AlephX thread:
“V1 and V3 fine tune the bias current. In keeping with the traditional Aleph values, we're looking for a nominal .5V across the Source resistors of the output MOSFETs. Regardless of what you set it to, make sure both sides match. You'll find that the pots give you a fair amount of latitude in setting the bias. As a general rule, more bias current is a good thing, but remember to keep an eye on the power being dissipated in your output devices; don't want to cook them.
V2 sets the absolute DC offset. Attach a test lead to one output, the other to ground. Adjust V2 to get the output-to-ground reading as close to 0V as possible. Let the amp warm up for at least 30 minutes. An hour is better. Readjust. Yes, it will drift a little afterwards, don't worry about it.”

/Hugo

[GlouBou]

Hello,

Thank you very much.

I will look this.

Kind regards

@+ GlouBou