The Aleph-X

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#2,582
😀

It's an answer to a question! The "other" AX thread pointed to it just yesterday, and the question was oooold on the end of this thread...but why leave it unanswered?

Find post 577 on this thread and see the genuine article, photographs courtesy of the man himself.
 
#2,583
Thanx to Mr. GRollins for schematics and Mr. Pass for brilliant inovations.

I used GRollins schematics to bild one prototype with some modifications. Values of variabile resistor are not correct but you can use two times biger values to be sure. DC output offset is solved with negative feedback to the source of the differential input stage. This isn't probably the best solution but it is simplest. I don't like those ground resistors of 32 ohms. I can't hear any difference in sound, but I like it this way.
So, if anybody is interested, here is the schematics.

Regards,
Marko🙂
 

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#2,585
Hello,
I don't like ground resistors because they looks to me like a fast solution of the DC offset problem. Still offset changes with temperature . I tried with some other solutions of this problem by they caused instability. So, I tried the simplest solusion, and it worked. Also you are lowering even harmonics distorsion and intermodulation distorsion.🙂
 
#2,586
There are a limited number of solutions to the DC offset situation. The resistors can actually be raised in value if other fixes are in place and tuned properly.
A servo works, if you don't mind servos. I prefer to avoid them if possible.
Close matching of parts, adjustment of the front end differential, resistors to ground at the ouputs, the resistors back to the base of the differential from the outputs...these are all part of the recipe.

Grey
 
#2,587
Hi!

A friend of me is interested to build the XA200 amp and he would like to know:
- what kind of brand are the small (0.25-0.5W) resistors in the amp?
-what kind of type and brand are the Zenners?

Thanks and greets:

Tyimo
 

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#2,589
For what it's worth, I generally use the Motorola/On Semi Zeners, which is to say that I tend to buy parts that I know I'll use more than one or two of in lots of 100 to catch the price break--and haven't used the Motorolas up yet.
I like Motorola, but have severe reservations about dealing with Newark Electronics, the supplier I used to order the parts from. I never, not once, had an order that went smoothly. Now that Digikey seems to be getting into On Semi, I may just order from them.
Mouser is a great source for the Vishay/Dale parts as long as they have the value you are looking for.

Grey

EDIT: I usually get the 1/2W resistors (RN65) so as to have more options as to where to place them in circuits. It keeps me from having to stock the same value resistor in more than one wattage. Pass Labs can afford the luxury, but I don't make any money at this so I spring for the extra two or three cents/ea. so as to be able to use them in tubes circuits or solid state or whatever. That said, the 1/8W parts are plenty for the signal level resistors in the Aleph-X. Go for it.
 
#2,590
GRollins said:
..., the 1/8W parts ...
Click to expand...

I am quite often ignorant and always make error in math. Moreover, I am unsure myself how much low power rating is acceptable for the resistors. Therefore, I try to keep my own minimum-3-times DIY rule. On top of that, I like to replace, e.g., 1/4W with 1/2W and 3W with 5W, taking into account that the resistivity might change by fractions due to the temperature changes. As far as I understand, the amp designers do not like dancing on temperature’s fall and rise. 🙂

You are welcome. Please correct my ignorance. 😀

Regards
jH
 
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