Aleph-X builder's thread.

[hilbert]

Re: Re: voltage question

Not being one of your hellfire-'n-brimstone religious folks, perhaps I'm getting this wrong, but if the topic is religion and you've got as much heat as a class A amp dissipates, then wouldn't that be hell instead of heaven? Perhaps it would be more appropriate to steal the copper off a Satanist church?

I dunno. That might lead to hell freezing over, and who knows what that might bring?
I wonder if any Swedish satanist church could afford a copper plated roof for me to snatch anyway.

The background story being the copper prices which are so high that we have frequent reports of churches having their copper platings and copper drainpipes stolen and sold for scrap. Who rips a roof of a church?

Yep, so futile that's it's the basis of the entire "X" line at Pass Labs.

Oh. Right.

But then an X:ed Aleph 0 might not be a bad choice after all (thanks again William)...
However, it's the ingenious simplicity of the Aleph X that got me hooked in the first place.

Btw, since I'm on the cheap track; stealin roof platings and what not, is there any rule of thumb to calculate the VA rating of an unknown transformer? I've seen some ads around for unlabled transformers...

The last I saw, there was a search function at www.analogsf.com that stayed fairly current. That should cover 99% of everything I've ever had published.

Yay! Procrastination, here I come!


But its 00:40 am, so maybe some sleep to dream up a nice Xification of the Aleph 0.

Hilbert

 

[yup]

Thanks William and Grey...

I am in the process of trying to match them now. I am using an Amatherm MS35 10018 inrush limiter. This is one hefty thermistor. It handles 18 amps of current and retains some of it's resistance when it's hot. Hopefully I can match them better.

Thanks,
Jeff

Picture

 

[Chois¢â]

My aleph-x finished with minor problem

Hi
I completed my project.
Everything normal, sound good.
But minor problem occured.
Abnormal DC offset(both relative and absolute)
raised when RCA input about 0.5V at + side of terminal.
I use toggle switch that - signal line connect to ground when
RCA input selected.
I didn't use coupling caps at both input.
Circuit was from kk-pcb.com.
What shall I do?

 

[wuffwaff]

Hi,

use two coupling caps at the input............

William

 

[Jozua]

Offset

Hi

This amp downfall as a DIY project is the extreme difficulties experienced in getting the DC ofset correct.

I have a working Aleph X but because of the DC offset problems I dont want to use it with my expensive speakers.

For me it was quite a expensive experiment.


Jozua

 

[Chois¢â]

It's my mistake

DC offset raised on - terminal when + RCA input.
- input connect to ground RCA input selected.

 

[Nixie]

Re: Re: Re: voltage question

Originally posted by hilbert
any rule of thumb to calculate the VA rating of an unknown transformer?[/QUITE]

Cross-sectional core area (in an EI core obviously that's the center bar of the E, or the sum of its two outer horizontal bars) is proportional to the square root of the VA. Assuming standard safety margin in avoiding core saturation, common core material, and 60 Hz mains, with area in cm^2, the constant of proportionality is around one.

Of course, such information has been posted many times on this forum already. Still, I know the 'search' function is a technology alien to most minds and its logic is difficult to master.

 

[steenoe]

This amp downfall as a DIY project is the extreme difficulties experienced in getting the DC ofset correct.

Jozua, please tell what the excact problems are? I am sure we can get it solved! I was in your position once, but here you go:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=93194 I was in a state to give up too, at some point. But finally the darn amp played music Man that music never sounded sweeter So do hang on! I recognized your cry for help, but now we all want to help
So, for starters could you post a schematic of your actual amp?
If not, please list some important values

Steen

 

[wuffwaff]

Jozua,

normally getting the relative offset (between the outputs) right and stable is no problem (just match and couple the input diff pair correctly). This is the only offset the speakers will see.
I´ve used my Aleph-X for over 2 years now without any problems (on some quite expensive speakers).

The absolute offset is a bit more difficult but should also be no problem if you follow the instructions.

William

 

[gaborbela]

HI
I just finished my AX about two weeks a go .
One side I managed the offset only I have 0.017V but another side I have 0.400V .
All the transistors and mosfets I did match as close as possible and still these big difference between the two channel .
Right now I'm waiting on Plitron transformer because the brand new transformer buzz like a tractor so I just return it .
Plitron promise they will replace it .
Regards

 

[steenoe]

Gabor, somehow I dont think its the Trafo's!
Steen

 

[gaborbela]

HI
Of course the transformer , it buzz like a tractor under load .
I not even connected both channel the same time . The speakers are dead silent . I talk about mechanical hum from the transformer . It sounded some how when charge some large capacitors continuously or like a over loaded motor ..
These is a large transformer 1.5KVA so not even possible to think about over load . The temperature of the transformer OK .
Actually the amp sound very good ,deep strong bass , open in the middle and nice top . Much better than my Aleph30 even do in the A30 I used better parts .
It is worth to sacrifice some time to get out the best of .

Regards

 

[metalman]

gaborbela,

Beware the presence of DC present on the AC lines. It takes very little of this to cause a trafo to hum. My trafos are for the most part silent, but every now and then they hum their own tune, and my multimeter handily confirms that there is some DC contamination on the AC wall socket when it happens.

Of course it could also be a faulty trafo. I'd check both.

Cheers, Terry

 

[Nixie]

Corrected version follows. No offense intended; think of it as constructive criticism.

Hi,
Of course it's the transformer: it buzzes like a tractor under load. It's not even connected to both channels at the same time. The speakers are dead silent. I'm talking about mechanical hum from the transformer. It sounded as if it were charging large capacitors continuously or like an overloaded motor...
This is a large transformer, 1.5 kVA, so it's not at all reasonable to consider an overload. The temperature of the transformer is OK.
Actually, the amp sounds very good: deep strong bass, open in the middle, and nice top. Much better than my Aleph30, even though in the A30 I used better parts.
It is worth it to sacrifice some time to get the best out of it.

Regards

 

[Magura]

Gabor, somehow I dont think its the Trafo's!
Steen

Nah, I'm with Steen on this one. I as well as steen have both experienced otherwise silent as a dead mouse trafo's going ballistic due to nasties in the mains.
Steen though looked rather funny as it happened to his brand new AX-100's first time


Magura

 

[Nixie]

Try mains filtering and a DC trap on the primary (though if it's an EI, DC is much less likely to be a problem).

 

[Babowana]

Re: My aleph-x finished with minor problem

I didn't use coupling caps at both input.

Mr. Choi,

Your amp looks much better than usual DIY.
Very nice finish!

By the way,
does the original design have any input coupling cap?
Where?

 

[tenderland]

new supply

Here is a more practical design, any input would be appreciated.


J

 

[Zen Mod]

Re: new supply

Here is a more practical design, any input would be appreciated.


J

12V6CT usually means twice 6V3

you'll have just half voltage

for your estimated voltages on output you need something in range of 24VCT

 

[tenderland]

dangerous

If I had a brain I would be dangerous....


ok how about sub the trany for


Hammond toroidal 182T12
300 va

24V ct @ 12.5A