Hi Guys,
I've been reading information on Aleph amplifiers for months and I would like to build an aleph 5 because it has some characteristics in its design that I consider quite important for a good amplifier such as: class a, single ended, few stages, use of mosfets.
But a person who should help me to build my aleph told me that alephs are not single ended amplifiers because there is no capacitor at the output.
Could you help me to demonstrate that aleph 5 design is a single ended topology? And why hasn't it got a capacitor at the output?
Thank you
I've been reading information on Aleph amplifiers for months and I would like to build an aleph 5 because it has some characteristics in its design that I consider quite important for a good amplifier such as: class a, single ended, few stages, use of mosfets.
But a person who should help me to build my aleph told me that alephs are not single ended amplifiers because there is no capacitor at the output.
Could you help me to demonstrate that aleph 5 design is a single ended topology? And why hasn't it got a capacitor at the output?
Thank you
Or many, if they are in parallel
The presence of a modulated current source at the output is not so clear cut for me.
ok. Thanks.
What I understood about single ended is that one device (or a set) manage the whole signal.
This device is always on. But to manage the whole signal (upper side and lower side of a sine wave for example) I need to move the working point of the device quite far from the cut off through an high bias current.
But in this way the fluctuating signal becomes "positive only" (even if oscillating) and a capacitor is needed at the output to eliminate the DC component and get a plus-minus signal again. And that should be the reason for a necessary capacitor at the output.
That's my poor understanding, sorry for that.
A capacitor is needed in a single supply unbalanced amplifier, regardless of whether they be Single Ended or Push-Pull. This is because in a single supply the output is floated at half-supply to ensure symmetrical clipping. Class D (and some Class A) amplifiers avoid this capacitor by driving two ends of the speaker with out of phase signals. There is still DC on the outputs, but because both are the exact same voltage, the speaker sees no DC.
Single ended is a type of topology where, as you correctly mention, only one apparent device may be used to drive the loudspeaker. However there are plenty of examples of SE amplifiers operating from dual rails or in balanced mode where no capacitor is needed.
Single ended is a type of topology where, as you correctly mention, only one apparent device may be used to drive the loudspeaker. However there are plenty of examples of SE amplifiers operating from dual rails or in balanced mode where no capacitor is needed.
I agree. An active current source is cheating
Little doubt this has been discussed in minute detail here previously.
Thanks Sangram.
So it is possible to have a single ended with no capacitor before the speaker. It depends on the supply and if an identical dc component arrive on both ends of the speaker.
I cannot chatch 100% what you explained because I’m not an expert but you gave me an help in some way.
Please, read my previous post, what I wrote should be true in single supply as you kindly explained.
So it is possible to have a single ended with no capacitor before the speaker. It depends on the supply and if an identical dc component arrive on both ends of the speaker.
I cannot chatch 100% what you explained because I’m not an expert but you gave me an help in some way.
Please, read my previous post, what I wrote should be true in single supply as you kindly explained.
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Similar debates raged for years about whether the JLH69 was push pull or single ended. I see it as clearly push pull because both devices are modulated by the signal and drive the speaker in counter phase. The aleph is unique in that it's variable and depending on how much you modulate the current source it sits anywhere between single ended and push pull with the optimal being somewhere away from either extreme. I see no point in trying to argue it as either.
There is some additional gain introduced by CCS... but you could try to "short-out" the 4 X 0.47ohm resistors connected in parallel, and see if you can tell the difference.
You may like the resulting sound better, for a few reasons: 1. the gain (good for Aleph 5..... or bad for Aleph 5.... hmmm...???) will be gone + 2. the damping factor will be improved and that is always a good thing, especially when you are starting at a low damping factor value in the first place.
Then, you will definitely have a single-ended, pure class A amplifier. Give it a go and tell us how it sounds.
You may like the resulting sound better, for a few reasons: 1. the gain (good for Aleph 5..... or bad for Aleph 5.... hmmm...???) will be gone + 2. the damping factor will be improved and that is always a good thing, especially when you are starting at a low damping factor value in the first place.
Then, you will definitely have a single-ended, pure class A amplifier. Give it a go and tell us how it sounds.
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As you've seen, opinions differ, but if you'd like to understand his reasons, there's no better source for the information than his own words. Slightly different context, but it is possibly relevant to your discussion with your friend.
https://www.diyaudio.com/forums/pass-labs/327244-pass-x250-repair-5.html#post6394291
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