The Aleph-X

[GRollins]

By definition, X is feedback. You can't build a 0dB feedback circuit and have it be X. That said, there's not a lower limit on X feedback...if you want 1dB feedback, it's yours for the taking. The upper limit is whatever the circuit will stand, in terms of open loop gain and stability.
I've got some admittedly rusty braincells that tell me that the open loop gain of a classic Aleph is somewhere around 40dB. Given that the closed loop gain is around 20dB, the math is simple: A standard Aleph has 20dB of negative feedback. By tube standards, that's high, but by solid state standards, it's low. Given that the open loop gain is limited, you're going to have to either redesign the thing for higher gain or accept lower closed loop gain if you want to increase feedback. If you want to decrease feedback, you can, but keep an eye on distortion, DC offset, and closed loop gain--a 40dB gain amplifier is all but unusable in most systems and the performance will decrease.

Grey

[Chois¢â]

Patrick

I tested your balanced protect circuit.
But I got wrong result.
CCS 2mA. Supply voltage 24V.
When relay on state, "+in" and "-in" point were 1.4V both.
To trip relay it needs 5.8V over at "+n" or "-in" point.
Plz help...

[RS232]

Hi everybody
I know this is a old thread but I got hold of 2 18V 300VA trannys and 1 very big heatsink and whant to bild the Aleph X.
Can someone point me to a workable board or to someone that still have some (2) boards for sale.
Thanks
Ric

[audiodan]

Hello Ric

A good idea is to go down to your local electronic shop and purchase some Universal pre-punched experimenters boards, not much to this amp and is very easy to use these boards, plus is more fun!

Dan

[Zen Mod]

Originally posted by Chois¢â
Patrick

I tested your balanced protect circuit.
But I got wrong result.
CCS 2mA. Supply voltage 24V.
When relay on state, "+in" and "-in" point were 1.4V both.
To trip relay it needs 5.8V over at "+n" or "-in" point.
Plz help...

you put -Vcc on gnd or on -24V ?

it must be -24V

[audioholik]

hi,

i just found this from here http://www.penguinlovers.net/audio/alephx60_proj.html

I did not use RCA, un-balanced mode as it so unstable in DC offset...... Some warns me "NOT" ever use un-balanced mode in A-X....

is this true?

i've been giving up my AX project since it always distorded badly if i increase the volume.
and yes im using unbalance.. i use 10K attenutor as passive volume.

are there any cure to fix this problem.

thanks

[Zen Mod]

Originally posted by audioholik
.......
are there any cure to fix this problem.

thanks

it's made for both balanced and unbalanced , with balanced as preferable (full SUSY blahblah)

best way , if you want someone to help you , is to bring :

1. exact schematic you use
2.exact measured voltages in important points
3.some pics of gadget itself

or you can wait a little , as soon I sharpen my bean-looking skills problem will be solved

[audioholik]

Originally posted by Zen Mod



it's made for both balanced and unbalanced , with balanced as preferable (full SUSY blahblah)

best way , if you want someone to help you , is to bring :

1. exact schematic you use
2.exact measured voltages in important points
3.some pics of gadget itself

or you can wait a little , as soon I sharpen my bean-looking skills problem will be solved

right now im using the transformer for something else..
heres the last measurement...

AFAIK it use kristijan schematics of aleph X. with little differences

notice there are lytic caps accros the input.







this is ps schematic, is this possible?


it use 8xIRF240/channel.
quiescent current about 1A. tried lowering to 0.5A but it didnt solve the problem.
thanks for your help

[EUVL]

> I tested your balanced protect circuit. But I got wrong result. CCS 2mA. Supply voltage 24V.
> Plz help...

Sorry for ridiculously late reply. I have not been watching the AX threads for years.

CCS 2mA is too low. J508 is 2.4mA, giving a max of 4.8V across one of the 2k resistors. This minus 0.6V drop across the 1N4148, and a further 3.3V across the zener, still gives 0.9V to turn the downstream transistor on. This is not the case with 2mA. You can make up for this by changing the 2k resistors (2x) at the collectors of the BC640s to say 2.4k or even 2.7k. The circuit should then functions properly.

To adjust trip point sensitivity, you can vary the values of both 1k resistors at the BC640 emitters (both simultaneously). E.g. when changing 2k to 2.4k, consider using 1.2k instead of 1k.

You might also need to adjust the value of the 150R power resistor to suit your relay. The valus is given by 2.4V / Relay on current. The 2.4V comes from the 3V zener - BD139 Vbe.

Hope it still helps. I have sent you a PM.
My sincere apologies.


Patrick

[ccschua]

hi audioholic,

your picture looks totally familliar from the china website.