First of all, we can ask JAMA.
Second, there will be a preamble to regulations which members must comply extreme.
Third: The clear rules maintain the friendship.
Fourth is a long way but ensure good sound.
With my friend Juan Antonio (JAMA) have done a good pool and do not mind looking like the most in order to pair them and ensure, DC free and very good linearity. Look you, who remain committed to the VFet. Recently we found in Japan, a new source of 2sk180 with the suffix c, and d. The same as the Japs replace and repair the 2sk77 Yamaha amplifier B1.
We also believe that the triode type curve vfet possess, it is more advantageous than you can get from its use.
The SE version, or CSX1-2, along with a full range speakers with high sensitivity, provide the listener a kind of sound very difficult to achieve with other devices that should fall to unnecessarily increase components, which are You should pair, and are not even vfet. In the case of use in vfet as followers, I think aloud and might be wrong. But that sacrifice triodes typical curve, we need to make ultra symmetrical drivers amplify and unfortunately latter have curved type transistor.
In short, we return to unnecessarily complex system to improve very little. And we raise the cost so much.
The engineer Nelson Pass has generously given his achievements and even some of their secrets against them, until it must compete, we have enthusiastic and he has continued to give more samples of their creativity and intelligence.
But I feel deeply that the most significant in all this is simplicity and I think that is the philosophy of these threads.
Second, there will be a preamble to regulations which members must comply extreme.
Third: The clear rules maintain the friendship.
Fourth is a long way but ensure good sound.
With my friend Juan Antonio (JAMA) have done a good pool and do not mind looking like the most in order to pair them and ensure, DC free and very good linearity. Look you, who remain committed to the VFet. Recently we found in Japan, a new source of 2sk180 with the suffix c, and d. The same as the Japs replace and repair the 2sk77 Yamaha amplifier B1.
We also believe that the triode type curve vfet possess, it is more advantageous than you can get from its use.
The SE version, or CSX1-2, along with a full range speakers with high sensitivity, provide the listener a kind of sound very difficult to achieve with other devices that should fall to unnecessarily increase components, which are You should pair, and are not even vfet. In the case of use in vfet as followers, I think aloud and might be wrong. But that sacrifice triodes typical curve, we need to make ultra symmetrical drivers amplify and unfortunately latter have curved type transistor.
In short, we return to unnecessarily complex system to improve very little. And we raise the cost so much.
The engineer Nelson Pass has generously given his achievements and even some of their secrets against them, until it must compete, we have enthusiastic and he has continued to give more samples of their creativity and intelligence.
But I feel deeply that the most significant in all this is simplicity and I think that is the philosophy of these threads.
Not an engineer. 😀
It is true that using VFETs as followers does not play as much to their
triode-like quality, but they do a nice job anyway. I have two examples that
seem to get lots of praise (and one that did not), and I intend to make some
more.
😎
The CS means Common Source. Maybe for clarity you would like to call it
CDX2.
Or you can call it Al.
The CS means Common Source. Maybe for clarity you would like to call it
CDX2.
Or you can call it Al.
Al - I like 😀
The CS means Common Source. Maybe for clarity you would like to call it
CDX2.
Or you can call it Al.
Or Betty....😛
Is it possible to use this frontend to drive a common source output stage with paralleled VFET's? Then we use the VFETs as gain devices, and have around 10 dB more gain, I guess.
not without some serious re-work (drawing almost trivial , several solutions possible , but all of them needing serious bench time)
in this FE you have one output node , for mentioned OS - you need two output nodes , antiphased
Preliminary listening impressions,
Overall the amp has lots of detail and is very enjoyable. I can see why Nelson has limited the descriptions of the sound of his amplifiers. Having had the A75, Zen amps, Aleph 3, F3, F5, BA-3, F6 and CSX1, I can tell you that they all have their unique sound. I am currently using DIY TAD horn speakers and need little power and damping factor for my speakers. That being said I can tell you that to date the CSX1 has been my favorite Amp. I turned it on and loved it from the beginning. Everything else has needed tweaking. The new (CDX2?) is in the second camp and you will want to play with the adjustment. The sound is stellar and worthy of building and maybe better than the CSX1, but not out of the box. The option of including the global feedback or not has made it very flexible and like the BA-3 greatly changes the sound.
To the sound, without the feedback it’s similar to the CSX1, but has more dynamics, bass quality, detail but less space than the CSX1. With the current feedback values that Nelson published (10dB) the bass tightens up and the sense of space closes in, it sound much more controlled. This is similar to the BA-3 with and without the global feedback, although I enjoy this amp much more without feedback than the BA-3 without. I will be very interested in trying the new values that that have made the CDX2 best the CSX1 in the opinion of Nelsons “listening panel”.
I will keep posting as I make changes. Currently C1 and C2 are 440uF, R37 and R38 are 2.5K and I’m running the bias on the outputs at 1.2A. and you will want bypass caps on the electrolytic caps C5 and C6.
So if you have the parts you will want to build this one.
🙂
Overall the amp has lots of detail and is very enjoyable. I can see why Nelson has limited the descriptions of the sound of his amplifiers. Having had the A75, Zen amps, Aleph 3, F3, F5, BA-3, F6 and CSX1, I can tell you that they all have their unique sound. I am currently using DIY TAD horn speakers and need little power and damping factor for my speakers. That being said I can tell you that to date the CSX1 has been my favorite Amp. I turned it on and loved it from the beginning. Everything else has needed tweaking. The new (CDX2?) is in the second camp and you will want to play with the adjustment. The sound is stellar and worthy of building and maybe better than the CSX1, but not out of the box. The option of including the global feedback or not has made it very flexible and like the BA-3 greatly changes the sound.
To the sound, without the feedback it’s similar to the CSX1, but has more dynamics, bass quality, detail but less space than the CSX1. With the current feedback values that Nelson published (10dB) the bass tightens up and the sense of space closes in, it sound much more controlled. This is similar to the BA-3 with and without the global feedback, although I enjoy this amp much more without feedback than the BA-3 without. I will be very interested in trying the new values that that have made the CDX2 best the CSX1 in the opinion of Nelsons “listening panel”.
I will keep posting as I make changes. Currently C1 and C2 are 440uF, R37 and R38 are 2.5K and I’m running the bias on the outputs at 1.2A. and you will want bypass caps on the electrolytic caps C5 and C6.
So if you have the parts you will want to build this one.
🙂
Thanks Botte for your detailed impressions. 🙂
Funny you like the CSX1 the most, the amp with 7 components 😀 and you have so many amps to compare them with.
I also listen to the CSX1 most of the time.
My parts are coming in from all over the world, so I will build one too.
Don't think we could name this amp CDX2 because the X stands for transformer...
Funny you like the CSX1 the most, the amp with 7 components 😀 and you have so many amps to compare them with.
I also listen to the CSX1 most of the time.
My parts are coming in from all over the world, so I will build one too.
Don't think we could name this amp CDX2 because the X stands for transformer...
ZM, I 'm not a designer and have a simple brain.....I was thinking of doing this: replace the N and P VFETS, top and bottom.
And bias the VFETs different.
Would this work?
Attachments
Hello WalterW. Overall negative feedback [as shown] will not be possible because the output stage now inverts signal phase. The gates of the SITs are properly biased; for example the voltage at the gates of SJ28s is +7V higher than their sources. Is your approach moving in a direction like that of CSX1?
Hi Antoinel, ah.. thanks, I didn't consider the inverting output stage 
So no global feedback, or I would have created a VFET oscillator...
But you are right, I would like to move in the CSX1 direction.
What I understand from the CSX1 article is that the input transformer would not be very capable of loading a few paralleled VFETs. So was hoping this new frontend is.
So no global feedback, or I would have created a VFET oscillator...
But you are right, I would like to move in the CSX1 direction.
What I understand from the CSX1 article is that the input transformer would not be very capable of loading a few paralleled VFETs. So was hoping this new frontend is.