Of course the Zen and SOZ were made as simple as
possible partly because that creates an attractive
starting point for DIYers. After we beat that design
up enough, we start adding stuff...
The XSOZ can be made pretty efficient with a single
polarity supply, a constant current source biasing the
diff pair, and Aleph current sources. In my test amps,
I get about 30%, meaning that a 30 watt output will
idle at 100 watts. A lot better than the 6% or so of
the original.
Still, resistive loading has it's charms, which is why I still
enjoy the lightbulb zen. And it has a nice warm glow.
possible partly because that creates an attractive
starting point for DIYers. After we beat that design
up enough, we start adding stuff...
The XSOZ can be made pretty efficient with a single
polarity supply, a constant current source biasing the
diff pair, and Aleph current sources. In my test amps,
I get about 30%, meaning that a 30 watt output will
idle at 100 watts. A lot better than the 6% or so of
the original.
Still, resistive loading has it's charms, which is why I still
enjoy the lightbulb zen. And it has a nice warm glow.
I am not quite gone yet, so:
Ian
If I needed more power/effiency even I would add some active currensources, so on that one i totally agre with You, but scouts honner, I am playing very loud music with this amp, and never at full volume, pleanty of headroom, so I don´t need more, but I am also shure that others wants more power.
I also think, that it is very easy to add those active currensource, and as I said before, I do think they also will sound good, I am not that religious in those matters.
I am glad that You like the pre- and power-amp "interface", it was nesesary to do something like this to avoide buffers, though it was very educational for me to work with them and You.
Impedances like those is what DIYers can do, but it is only the the X-SOZ that will suffer when connected to an other sources, the X-BSOZ will fit anywhere, even to headphones.
Thanks for Your support along.
Ian
If I needed more power/effiency even I would add some active currensources, so on that one i totally agre with You, but scouts honner, I am playing very loud music with this amp, and never at full volume, pleanty of headroom, so I don´t need more, but I am also shure that others wants more power.
I also think, that it is very easy to add those active currensource, and as I said before, I do think they also will sound good, I am not that religious in those matters.
I am glad that You like the pre- and power-amp "interface", it was nesesary to do something like this to avoide buffers, though it was very educational for me to work with them and You.
Impedances like those is what DIYers can do, but it is only the the X-SOZ that will suffer when connected to an other sources, the X-BSOZ will fit anywhere, even to headphones.
Thanks for Your support along.
Almost gone, but:
I really have enjoyed making this as simple as possible, and still I havn´t got that feeling, that I have to "start adding stuff" as Nelson does.
So I will stick to the true spirit of ZEN.
I really have enjoyed making this as simple as possible, and still I havn´t got that feeling, that I have to "start adding stuff" as Nelson does.
So I will stick to the true spirit of ZEN.
i don´t know how much Nelson build, and which one he uses, but i´m pretty shure that one the pic isn´t balanced.
http://www.passdiy.com/images/projects/zenlite-rear.jpg
http://www.passdiy.com/images/projects/zenlite-rear.jpg
I run them as balanced monos, with 6 300 watt bulbs
per channel. This is bigger than the published project,
although I did mention it, and runs at the edge of hotness.
Another possibility that bubbles to the surface is to combine
the active current source and resistive load in parallel. This
way we could look at some of the charm of the resistive
bias, say at 16+ ohms, and still use an Aleph source to
raise the efficiency.
I'm sure that one of you bright bulbs could cobble this
together for the thread.
per channel. This is bigger than the published project,
although I did mention it, and runs at the edge of hotness.
Another possibility that bubbles to the surface is to combine
the active current source and resistive load in parallel. This
way we could look at some of the charm of the resistive
bias, say at 16+ ohms, and still use an Aleph source to
raise the efficiency.
I'm sure that one of you bright bulbs could cobble this
together for the thread.
It looks nice, but I think this would be more akin to a balanced ZV2. If I'm not mistaken (and that's a certain possibility), in order to X-ify it you'll need to pin a tail on the long-tailed pair in the form of a normal CCS.
Mike
Mike
henrik, ever thought of making an additional tail current source (connecting r16 and r17 to negative supply).
So q4 and q8 floating between 2 active current sources and perhaps double feedback loops (kind of r36 and r38 on negative side).
Curious wath the effect could be.
In that way we could play with different values for feedback from pos and neg side (if there's a difference, it must be caused by q4 and q8) to add to the diff. pair.
just an idea, perhaps not a good one
So q4 and q8 floating between 2 active current sources and perhaps double feedback loops (kind of r36 and r38 on negative side).
Curious wath the effect could be.
In that way we could play with different values for feedback from pos and neg side (if there's a difference, it must be caused by q4 and q8) to add to the diff. pair.
just an idea, perhaps not a good one
Henrik,
Geat work by Henrik and others in the thread. Mr. Pass has a nack for giving the right information at critical points.
Are you able to measure how much feedback is being used in your X-BOZ and X-SOZ?
I have seen feedback commonly given in db.
How can it be calculated?
Thanks
Geat work by Henrik and others in the thread. Mr. Pass has a nack for giving the right information at critical points.
Are you able to measure how much feedback is being used in your X-BOZ and X-SOZ?
I have seen feedback commonly given in db.
How can it be calculated?
Thanks
general idea behind previously mentioned post: 'balanced' feedback-loop on an diff. pair.
Could be also a way for better tracking current draw of load.
Remember, just an idea, perhaps not even worth thinking about.
Could be also a way for better tracking current draw of load.
Remember, just an idea, perhaps not even worth thinking about.
You need some input resistance for this to work the
way you want. This could be provided by the output
impedance of whatever will be driving it.
A pair of .5 resistors at ground is a little low for the X
effect as it is as low as the transconductance of the
gain devices, and only a percentage of the distortion
will be nulled. A high impedance current source, by
contrast, will give the whole effect.
Nevertheless, it is now technically an X amp.
To measure the amount of feedback being applied to
this circuit, drive it with a load and a source having very
low impedance and measure the gain. Then drive it with
the finite impedance you will be using in real operation
and compare the two figures.
Divide the lower figure into the greater, find the log10
of this and multiply by 20 and you have the decibels.
way you want. This could be provided by the output
impedance of whatever will be driving it.
A pair of .5 resistors at ground is a little low for the X
effect as it is as low as the transconductance of the
gain devices, and only a percentage of the distortion
will be nulled. A high impedance current source, by
contrast, will give the whole effect.
Nevertheless, it is now technically an X amp.
To measure the amount of feedback being applied to
this circuit, drive it with a load and a source having very
low impedance and measure the gain. Then drive it with
the finite impedance you will be using in real operation
and compare the two figures.
Divide the lower figure into the greater, find the log10
of this and multiply by 20 and you have the decibels.
How to make it
Hi,
Once in a mag called TAA they often say, make it like the the big boys do it.
So... I make a pair of full range quasi ribbon loudspeakers I don't know that the bass panel was ribbon so I did it my way and... it works even better than the original just my own design.
I bought a MLSSA and som other measurement equpiment and started to measure, one thing is obvious you can more than you happens to know, keep o trackin'
Hi,
Once in a mag called TAA they often say, make it like the the big boys do it.
So... I make a pair of full range quasi ribbon loudspeakers I don't know that the bass panel was ribbon so I did it my way and... it works even better than the original just my own design.
I bought a MLSSA and som other measurement equpiment and started to measure, one thing is obvious you can more than you happens to know, keep o trackin'
Thanks, Nelson Pass.
Every word seems like a thousand to me.
Being really encouraged, I will take this X as my new project.
Before I light its fire, however I¡¯d like to come up with a further
developed circuit, with a brief description.
I'm with you, leiade, about the philosophy.
By the way, I wish to see someone tackling this:
"Another possibility that bubbles to the surface is to combine
the active current source and resistive load in parallel. This
way we could look at some of the charm of the resistive
bias, say at 16+ ohms, and still use an Aleph source to
raise the efficiency."
Best Regards
Every word seems like a thousand to me.
Being really encouraged, I will take this X as my new project.
Before I light its fire, however I¡¯d like to come up with a further
developed circuit, with a brief description.
I'm with you, leiade, about the philosophy.
By the way, I wish to see someone tackling this:
"Another possibility that bubbles to the surface is to combine
the active current source and resistive load in parallel. This
way we could look at some of the charm of the resistive
bias, say at 16+ ohms, and still use an Aleph source to
raise the efficiency."
Best Regards