The Aleph-X

Jump to Latest
#2,081
Fritz said:
Rf/Ri

That helps, Now I just have to figure out the schematic well enough to recognize which are input and feedback resistors in the various stages.

zero gain, that means your just controlling current with the thing?

Thanks
Click to expand...

R16 and R30 are the feedback resistors,

R19 and R29 are input-to-ground resistors,

and of cource R18 and R28 input resistors.
 
#2,084
Looks like if I change the feedback R to 221 K Ill have a gain of 26.9 dB. Probably close enough (.4%) to the 27dB Im aiming for.
Looks like Ill have to measure to perform the sensitivity calcs?

Now this defines the slope and intercept of the amp but if I put different loads on the two amps does this relationship break down? Especially with respect to sensitivity?
 
#2,085
powe supply question on Aleph-X

Nelson said that he would like the rails on an Aleph-X to be +25 0 -25

I saw some 20 volt transformers rated at 20 amps. I surmise that I could use two of these in a +25 0 -25 power supply for an Aleph X. Is the 20 amp rating enough?

I would be driving a 4 ohm or so load...how many watts would the amp be capable of given the above transformers?

Thanx in advance...
 
#2,088
Hi,

did somebody else try to change the 30ohm to ground to stabilize absolute DC offset to about 100 ohm like Nelson has in his XA200?

I tried about 88ohm (2x 175 ohm) and it works ok, it stabilizes within 30 seconds to about 0.2V and startup wasn't higher than 2V to begin with ... I think this is considered normal is it? I will change it back tomorrow to 30 ohm to check out the difference in speed and behavior!

Edwin
 
#2,091
Edwin Dorre said:
Hi,

did somebody else try to change the 30ohm to ground to stabilize absolute DC offset to about 100 ohm like Nelson has in his XA200?

I tried about 88ohm (2x 175 ohm) and it works ok, it stabilizes within 30 seconds to about 0.2V and startup wasn't higher than 2V to begin with ... I think this is considered normal is it? I will change it back tomorrow to 30 ohm to check out the difference in speed and behavior!

Edwin
Click to expand...


I'm not using them at all and it takes about an hour and half to get down to 0V, after that it stays there.😉
 
#2,092
Edwin Dorre said:
Hi,

did somebody else try to change the 30ohm to ground to stabilize absolute DC offset to about 100 ohm like Nelson has in his XA200?

I tried about 88ohm (2x 175 ohm) and it works ok, it stabilizes within 30 seconds to about 0.2V and startup wasn't higher than 2V to begin with ... I think this is considered normal is it? I will change it back tomorrow to 30 ohm to check out the difference in speed and behavior!

Edwin
Click to expand...


Yep, I am using 100. Short of doing what peter did, which I may do at somepoint soon in the future I tried all kinds of values from 10 to 200 It doesn't seem to be making any diff.
 
#2,093
Peter Daniel said:



I'm not using them at all and it takes about an hour and half to get down to 0V, after that it stays there.😉
Click to expand...

What do you call 0V? Mine floats very slowly (many many minutes) between 0.2V to -0.2V back and forth. Sometimes it stays a while (10 minutes) around 0.04V sometimes it does not.

I have to mention, I have a weak power supply with a 2V of ripple on it 🙂 I have to order better transformers and a load of elco's and ntc's...

Edwin
 
#2,096
Re: Silly question from a Headphone listener....

ljordan said:
Does anyone know of a version small enough for about 1 to 2 watts output? I use Sony mdr f1s (12 ohms) which sound best driven by a small power amp.
Lewis
Click to expand...
Note the Aleph-X is balanced output, which may not be possible with your headphones at all, but at the minimum would require cutting up your cable.

This one should work:
http://headwize2.powerpill.org/projects/showproj.php?file=pellerano_prj.htm

Also take a look at Grey's Mini-A:
http://www.diyaudio.com/forums/showthread.php?threadid=2001&highlight=MiniA
 
#2,097
Nelson Pass said:



12 volts is a bit low, even if you mean +/- 12 volts. The Mosfets like some extra voltage the same way they like some extra bias, and I would expect only 10 to 15 watts, and not particularly good watts, either. The minimum I work with is +/- 25 volts, and of course you can get higher voltage switching supplies...
Click to expand...

It is said that Rushmore is using AX 40 watt amp in bass region. How high are the rails then?
 
You must log in or register to reply here.
Top Bottom