My AB amp inspired by AlephX

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LBHajdu

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Joined 2002
I had the time so I drew up the schematic. I changed the layout slightly for more symmetry. The lines are a little bit thicker then I would like. It must be checked for errors. I’m almost positive there are some. All you need do is to fill in the values.
 

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DarkOne

DarkOne

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Joined 2001
So, here it is.

- M1-4 should be thermally coupled
- M22 & M24 have to be on heatsink with output transitors
- current limiters configure to your own taste (i use 15A), or eliminate them

2 LBHajdu: nice schematic and looks correct, I don't have pdf editing tool (can just print), so I post it this way
 

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Nelson Pass

Nelson Pass

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LBHajdu said:
That’s very interesting, I’ve never heard of a class A\B push pull amp describe as “very smooth”. I wonder if it’s distortion from the output stage. Is there a high end roll off?

I also wonder if that is why Mr. Pass didn’t use this topology in his amps.
Click to expand...

Well, I can't use them all, now can I?

I played with something similar, but I found it worked better as
a Class A, no surprise there.

:cool:
 
DarkOne

DarkOne

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Joined 2001
LBHajdu said:
That’s very interesting, I’ve never heard of a class A\B push pull amp describe as “very smooth”. I wonder if it’s distortion from the output stage. Is there a high end roll off?

How is the noise floor, is there any hum? This is the Achilles heal of common source operation as you know. However the symmetry must help out some what.

I also wonder if that is why Mr. Pass didn’t use this topology in his amps.
Click to expand...


Sorry LBHajdu, I missed your post.

So, i had problem with hum, it was very disapointing, but I found that was due ground loop, which I eliminated. Still can hear hum, but I have to put my ears 10cm from cone, the same is with noise (speakers are 87dB/W). I don't know if this is good result, because I haven't tried other amplifiers. I must also note that signal cables are not shielded and long and I didn't match output transistors perfectly (one half is running 1.15A and the other 0.7A bias), future versions will eliminate this (still learning).

Measured noise level with my multimeter is around 0.2mV

"smooth sound" - maybe I used wrong words. Sound is detailed, dynamic and not agressive (in my words it's smooth)
 
rif

rif

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DarkOne and/or LBHajdu:

This may be a naive noob question, but I'm having trouble finding the BC560, BC550, ZTX451, ZTX450 transistor information (sorry I may have gotten those slightly off -- don't have it in front of me).

I wanted to run a model in spice, but can't determine who the proper manufacturer is. Example: I thought the ZTX would be Zetec, but they have both 450/451 listed as NPN, which doesn't jive with the circuit schematic posted above.

thanks
 
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