Aleph-X builder's thread.

[yoke]

Thanks Piotr, that will be great...
I will try to replace trimer with resistor, and see how will he performe...
The strange thing is that when I set it two day ago and mesure resistance on trim pot it was around 1.5K, yesterday it was around 3K...

but I won't give up until I figure it up...

 

[arthur]

aleph x dc servo cut off frequency

if c*r=1 sec,absolute output dc can be restricted to within 15mv
if c*r =0.1 sec op offset within several mv

Please advice what cut off frequency should i use
(i use dc opamp servo to control the i/p stage ccs)


Thanks

 

[CH2]

Hi All

I have completed my Aleph-X. But I am stuck with a little problem on my left channel. The voltage on the speaker port is 6V with reference to the ground. And I can't tune the voltage down with the VR. The right channel is fine.

I don't know what did I mess up within the circuit. Any opinion or suggestion would be greatly appreciated.

Thanks

Hock Hua

 

[Nelson Pass]

Is is + or - ?

 

[Caiofrv]

Test

Test TEst

 

[CH2]

Is is + or - ?

Its +.

After 4 hours of running, it lower to 5.6V. I am using Grey's version. The 9.1 zener Diode measured 8.9V. The VR can only increase the absolute offset.

I tested the channel, it is singing alright.

Cheers
Hock Hua

 

[arthur]

may need replace the ccs 9610

 

[CH2]

may need replace the ccs 9610

Thanks for the reply.
Is that the Q6a or the pair of IRF9610(Q5&7)?

Cheers
Hock Hua

 

[dieringe]

Is that the Q6a or the pair of IRF9610(Q5&7)?

the single one which makes constant current, so it should be Q6

 

[CH2]

OK

But what should I replace the IRF9610 with? Another IRF9610 with lower or higher Vgs?

Thanks

 

[yoke]

Now that's it...I have it enough...After trying to set AC current gain for a week, today I finely give up...
My amp did play music but I could not set it to 50%...today I got some white smoke from one mosfet ( or resistor ) ...so I have it...
Maybe I will make normal version of X, or use parts and try to make some Aleph...
Don't know.......
Agggrgghgghhhhhhhhhhh

Well I could build GC for start.........

 

[Netlist]

Yoke,

Don't give up, give it a rest for a few days.
Believe me, this is such a nice amp it would be a shame to stop now. As you say it plays music, you’re on the right track.
Get yourself a beer or a nice glass of wine, get some fresh air and come back. I'm sure you'll sort it out. Too many are waiting now for your first listening session.

/Hugo

 

[yoke]

I don't know what was wrong...I know why it play white smoke...but I don't know why I could not set it to 50%...I trim it , replace it with resistor , and then I get 40 or 60%...but when I touch R12 with my fingers it goes up or down to 50%...( It doesn't make since to me )...
O.K. if it have to rich some temperature to be stabile ( my heatsinks goes to 60-65*C ), but with sime resistance in place of R12 , one day I have one % the other day other ??? And it's not small %...
The other thing is that when I live out R12,R34 I get voltage on R5=5mV, R2,3=36mV ,R6=40mV
R40=5mV, R=42,43mV ,R41=40mV

When I place trimer I get R12 of 3,14K and R34 of 2,6K ??? well it look like they should be the sime by the numbers above...

R5=19mV, R2,3=36mV ,R6=21mV
R40=20mV, R=42,43mV ,R41=22mV ... or some thing like this, but in time this change to

R5=15mV, R2,3=36mV ,R6=23mV,or R5=11mV, R2,3=36mV ,R6=27mV
R40=21mV, R=42,43mV ,R41=25mV ...

The difference is that R12 is closer to heatsink then R34...but could difference be that big??? this all is measure with open chassis...


The worst thing that sound was not bad...I have lisen only one channel so I can't compare it with stereo or anything...( stereo sounds much bather than one channel )...everything was clear,bass was strong and clear,hights was o.k....( well this was played from PC...but any way...)

 

[yoke]

have any one build some version with 8 mosfet and around 4A bias, 20-25V...maybe I could use his R12 value ???
Is there any way I could calculate R12 value ???

 

[dieringe]

But what should I replace the IRF9610 with? Another IRF9610 with lower or higher Vgs?

only if it's broken. the idea is that something might be wrong with the your current source, resistor/zener/transistor

 

[Netlist]

I don't know how to calculate R12/R34 other than the method described by Nelson. Something like 1k should do the trick to start with. That is with the original schematic.
I would start doing that, and look if the amp is stable in time.
You probably won't have the exact 50% but in the meantime you could listen and try to debug other possible mistakes. 3.14k and 2.6k seems a bit high.

One important thing to consider:
Is the amplitude of your input source constant? Small variations
will have big influence on the measurements.

/Hugo

 

[yoke]

I don't know how to calculate R12/R34 other than the method described by Nelson. Something like 1k should do the trick to start with. That is with the original schematic.
I would start doing that, and look if the amp is stable in time.
You probably won't have the exact 50% but in the meantime you could listen and try to debug other possible mistakes. 3.14k and 2.6k seems a bit high.

One important thing to consider:
Is the amplitude of your input source constant? Small variations
will have big influence on the measurements.

/Hugo

I belive that input is constant...I play sine wave directli from PC to amp...

When I first start to building AX I was hopeing that 1.5K would do for R12...whell, first time that I mesure resistance of trim pot it was around 1.5K, then it starts to rise to 2K,3K...

Does R5 and R2,3 have to be the sime value...( my R5 is 0,5 ( I have two of them ) and R2,3 are 0,44 ( 0,22+0,22 ) ???

One more question, how do you chack if mosfet is broken ?!?

 

[yoke]

After this one is gone with white smoke

I put this in a 15min...

( thanks to Brian GT who send me resistors as extra )

GC – what can I say, not much to see but it plays music...power suplay is from AX...

Now back to AX...
Can someone please tell me how to check if mosfet is broken?

 

[Netlist]

I quickly jump in with this: http://www.bcae1.com/
Look for #97 on the right pane: Output transistor failure.
Also, try to study the Aleph current source again.

Now back to what will probably be the last barbecue this year

/Hugo

 

[yoke]

Big Thanks Netlist...