Getting rid of an active current gain in Aleph
I would like to try converting the Aleph output stage into a simple current sourced stage. All the feedback around the current source, the out series resistors, all the parts hanging on the output are influencing sonics in some way. A simple Mosfet with a fixed current source should sound probably better. I do lose the power into 4 ohms and lower but this is not an issue here.
Natural progression of course, is SOZ with single resistor for current source, but at the cost of efficiency. So I would be leaning towards simple, active CS.
Anybody tried doing that already?
I would like to try converting the Aleph output stage into a simple current sourced stage. All the feedback around the current source, the out series resistors, all the parts hanging on the output are influencing sonics in some way. A simple Mosfet with a fixed current source should sound probably better. I do lose the power into 4 ohms and lower but this is not an issue here.
Natural progression of course, is SOZ with single resistor for current source, but at the cost of efficiency. So I would be leaning towards simple, active CS.
Anybody tried doing that already?
Peter
Gray did this nice job:
http://www.diyaudio.com/forums/showthread.php?threadid=772
and you can X it if you want, but the cost is lower inputimpedance if you dont want to use a buffer.
Gray did this nice job:
http://www.diyaudio.com/forums/showthread.php?threadid=772
and you can X it if you want, but the cost is lower inputimpedance if you dont want to use a buffer.
Thanks for a link, somehow I never got to see that thread. But it's more of a variation on SOZ design.
What I'm looking for, is a modified Aleph, with mosfet as a current source, but without the circuit associated with active current gain. I'll be using that amp in tri-amp system with efficient drivers, so I don't need extra power and if I'll be able to achieve better sonics, it's worth it.
What I'm looking for, is a modified Aleph, with mosfet as a current source, but without the circuit associated with active current gain. I'll be using that amp in tri-amp system with efficient drivers, so I don't need extra power and if I'll be able to achieve better sonics, it's worth it.
And I would like to use X topology, and experiment a bit with the boards I got.
It will not surprise you to imagine that I have
worked with this a bit.
There are occasions when a constant current source
or even a resistor will sound better, but this is highly
dependent on taste and having the proper speaker.
A good example is a nice efficient horn midrange or
tweeter. If you don't need the power, you have less
need of gain in the circuit.
pass/ - likes a good horn now and then
worked with this a bit.
There are occasions when a constant current source
or even a resistor will sound better, but this is highly
dependent on taste and having the proper speaker.
A good example is a nice efficient horn midrange or
tweeter. If you don't need the power, you have less
need of gain in the circuit.
pass/ - likes a good horn now and then
Nelson Pass said:
Yes, especially if you already have a preamp in the loop, which for loudspeakers in the 95dB+ wouldn't necessarily require any additional voltage gain. And if you don't need any voltage gain, the circuit can reduce to an emitter/source/cathode follower, which is simpler, more linear and has a lower output impedance (assuming an active current source).
se
Re: sound
I just wanted to try to make a Push Pull for a change. I am shure Neslon coud do a much better job, actually he once said he would consider it, but you know.......
´s!
The sound was OK, but compared to my XSOZ not so good.uli said:Henrik,
how does it sound compared to an Aleph?
Uli
I just wanted to try to make a Push Pull for a change. I am shure Neslon coud do a much better job, actually he once said he would consider it, but you know.......
´s!
Re: Getting rid of an active current gain in Aleph
peter:
i saw a project for this. i'll find the link and send it or the schematic later.
mlloyd1
peter:
i saw a project for this. i'll find the link and send it or the schematic later.
mlloyd1
Peter Daniel said:I would like to try converting the Aleph output stage into a simple current sourced stage.....
Anybody tried doing that already?
Nelson Pass said:
Yeah, all night long...
I have three different Zens in hand:
- The original Zen with constant current source
- Zen with active current source
- Zen-X with active current source
I like all three, particularly the Zen-X with the "active current source." It attracts me best for the clear sound with the musical texture, harmony and resolution. The Zen-X has performed its duty on 1.32A bias current. By the way, why not lower bias if the sound remains the same? I have thought about the lower bias to my curiosity. To lower the bias, however I have not changed the bias resistor value. Instead, I have approached the current source of Aleph, by adding R19 (of Aleph 2). I have got 1.16A with 120k and 0.96A with 60k. Now, it is fixed with 1.16A.
Expecting a valuable conclusion of Peter Daniel...
JH
Peter Daniel
May I propose you to change the thread title to "rate and effect of the ac current gain" or similar?
I actually experimented on Zen-X with ac current gain variation from 0 to 50%. I felt that the +/- ac current rate control worked as if to be equivalent to the +/- focus control of camera lens. My preference zone was 0-30%. In between these values, the differences were not very distinctive, and the preferences were dependent on the different music and mood.
Again, looking forward to your results¡¦
JH
May I propose you to change the thread title to "rate and effect of the ac current gain" or similar?
I actually experimented on Zen-X with ac current gain variation from 0 to 50%. I felt that the +/- ac current rate control worked as if to be equivalent to the +/- focus control of camera lens. My preference zone was 0-30%. In between these values, the differences were not very distinctive, and the preferences were dependent on the different music and mood.
Again, looking forward to your results¡¦
JH
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