Aleph-X builder's thread.

[Aud_Mot]

Please note that the XLR pin numbering on the schematic is contrary to most XLR pin conventions.

For proffesional gear the pin out is as follows:

Pin 1: Ground or Sheild
Pin 2: High, +, or Non-inverting
Pin 3: Low, -, or Inverting

Some consumer equipment might be wired to a different convention.

Double check your source equipment to match up by signals not pin numbers.

Aud_Mot

Ps Chad great job all around. Best $5.00 I have ever spent.

[goskers]

Hi all,

Have got a few boards and am contemplating jumping into this amp building stuff but am not quite sure what the range of cost to build. How much does the aleph x cost to build per channel?

If you are building multiple channels can you share power supplies or do you need to do it per channel?

Thanks for any help.

[MikeW]

Most of the AX built are low voltage (15-20) high current (6-10). The First Watt is going to have 24 volt rails for a ten to fifteen watt amp.
There must be a reason for the higher rails. Should these be built using 25 volt rails with 3-6 amp bias?

[grataku]

Originally posted by Aud_Mot
[B]Please note that the XLR pin numbering on the schematic is contrary to most XLR pin conventions.

For proffesional gear the pin out is as follows:

Pin 1: Ground or Sheild
Pin 2: High, +, or Non-inverting
Pin 3: Low, -, or Inverting

Some consumer equipment might be wired to a different convention.

Double check your source equipment to match up by signals not pin numbers.

[B]

A non-issue really that was discussed before but alas the schematic was never modified.
Just keep in mind that the actual receptacle should be connected in the usual manner. It is pretty clear why the board end needs to be the way it is.

[yoke]

Originally posted by MikeW
Most of the AX built are low voltage (15-20) high current (6-10). The First Watt is going to have 24 volt rails for a ten to fifteen watt amp.
There must be a reason for the higher rails. Should these be built using 25 volt rails with 3-6 amp bias?

I do remember that Mr. Pass once told, long ago, that he would not go below 25V...or was it 20V...

I will use 20-25V and 4 A for my version, 8 mosfet per canal...

Regards
Josip

[SGregory]

Thanks Chad and everybody for makng the x boards possible. In the process of building mine with 22.3V Rails and 10 amp bias. In the process of building power supply and chassis now and am very interested in other peoples opinion about the options. Read the thread but by the time I was finished forgot half no 90% of what I read. I guess I will start from the beginning

Regards Scott

[bertram]

Hello,

this is my first DIY audio project in almost 20 years. My soldering iron is already hot... Some questions:

- Is somebody planning to sell matched FETs?

- Is it a good idea to replace D1 with 1N938 (reference diode 9 Volt with very low temperature gradient)? It is rated with 500 mW but only 7.5 mA. Although in its data sheet this current is rated as max. current, I assume that it is meant as max. current with guaranteed temperature stability (how else would you get 500 mW?) When exceeding this current, temperature stability should still be much better than compared to standard zeners. Or does the diode break with more than 7.5 mA?

- Which type of power resistors would you use?

- I have not found the transistor MPSA18 so far in Germany. By which European type can it be replaced without affecting sound quality and the original resistor values?

- Is there any benefit in using a rectifier bridge for each of the supply voltages vs. using only one bridge delivering both supply voltages?

- I am aiming at a CLC filter in my power supply. Which choke manufacturers should I look for?

P.S.: Nelson, thank you very much for everything!!! I understand that you love a bottle of good red wine from France. I am living in a wine producing region and will try to convince you that there are also very good German red wines. To all others: wouldn't this be a subject for a group buy in favor of Nelson?

[Taco]

Originally posted by bertram
Hello,

this is my first DIY audio project in almost 20 years. My soldering iron is already hot... Some questions:

- Is somebody planning to sell matched FETs?

- Is it a good idea to replace D1 with 1N938 (reference diode 9 Volt with very low temperature gradient)? It is rated with 500 mW but only 7.5 mA. Although in its data sheet this current is rated as max. current, I assume that it is meant as max. current with guaranteed temperature stability (how else would you get 500 mW?) When exceeding this current, temperature stability should still be much better than compared to standard zeners. Or does the diode break with more than 7.5 mA?

- Which type of power resistors would you use?

- I have not found the transistor MPSA18 so far in Germany. By which European type can it be replaced without affecting sound quality and the original resistor values?

- Is there any benefit in using a rectifier bridge for each of the supply voltages vs. using only one bridge delivering both supply voltages?

- I am aiming at a CLC filter in my power supply. Which choke manufacturers should I look for?

P.S.: Nelson, thank you very much for everything!!! I understand that you love a bottle of good red wine from France. I am living in a wine producing region and will try to convince you that there are also very good German red wines. To all others: wouldn't this be a subject for a group buy in favor of Nelson?

-here in the Netherlands is a small company which sells mathed fets (www.specmail.nl), don't know if they deliver to places outside Holland

-D1, don't know a std zener works fine for me

-I used intertechnik mox4 (www.intertechnik.de) 4watt 2% and availible in 0.22 ohm

-I use a single bridge, but double bridge will give lower noise.

-for choke's I urge you to look at what intertechnik have to offer, you'r looking for air-core coils. I use a CRC filter, because power resistors are cheaper ... .

[gpsmithii]

Hello,

I too will be constructing an Aleph X in the very near future. I'm finishing up an A40. I have contacted Avel Lindberg and one of their distributors in an effort to get them to set up a "special code" ..... if you will whereby one could call them and place an order for an off shelf Toroidal Transformer that meets the requirements of your specific project. They accept credit cards, and will ship out of the US to approved countries. I would also be glad to contact Mouser, DigiKey, and other suppliers and attempt to make the same arrangements if there is enough interest. I'm looking into heatsinks also. There is real purchase power in the masses I'll keep you posted.

[GringoAudio]

...is in the Aleph-Xorder discussion. I got a quote from Plitron. Perhaps we would get a discount from them too with an account number like you have suggested. What transformer is the one people would want to use. Quantity discounts would be based upon ordering the same transformer no doubt.