I'll email you tomorrow Richard. I just got a call from a friend yesterday about using those speakers in a new pro audio monitor. I do need to have the low carbon steel parts made in Asia, you can't get any low carbon steel here except for sheet metal or very expensive electric steel from someone like Carpenter. They only want to take to you if you are ordering literally tons of electric steel.
RNMarsh
I used to get the Japanese audio technology magazine called MJ. Could not read any of it but the data and schematics told the story.
Here is a commercial design of 14 years ago being written and explained from issue 8, yr 2000.
I modeled the VAS on the proposed scheme, the search
that's what came out of it
[/URL][/IMG]
[/URL]
I in my designs using broken cascode
[/URL][/IMG]
[/URL]
best regards
Petr
I used to get the Japanese audio technology magazine called MJ. Could not read any of it but the data and schematics told the story.
Here is a commercial design of 14 years ago being written and explained from issue 8, yr 2000.
I modeled the VAS on the proposed scheme, the search
that's what came out of it
[/URL] I in my designs using broken cascode
[/URL]best regards
Petr
RNMarsh (4221)
I used to get the Japanese audio technology magazine called MJ. Could not read any of it but the data and schematics told the story.
Here is a commercial design of 14 years ago being written and explained from issue 8, yr 2000.
I modeled the VAS on the proposed scheme, the search
that's what came out of it
http://s57.radikal.ru/i156/1401/b7/3b0043aab7be.png
I in my designs using broken cascode
http://s019.radikal.ru/i610/1401/39/235f2cf252a7.png
best regards
Petr
I used to get the Japanese audio technology magazine called MJ. Could not read any of it but the data and schematics told the story.
Here is a commercial design of 14 years ago being written and explained from issue 8, yr 2000.
I modeled the VAS on the proposed scheme, the search
that's what came out of it
http://s57.radikal.ru/i156/1401/b7/3b0043aab7be.png
I in my designs using broken cascode
http://s019.radikal.ru/i610/1401/39/235f2cf252a7.png
best regards
Petr
That is a very clever output buffer..🙂
could be a very very good linestage as well. for line-level signal you can probably run without any feedback and still get good results.
could be a very very good linestage as well. for line-level signal you can probably run without any feedback and still get good results.
Last edited:
Hi Egra !
I guess that `magic ` and life like sound you have get using that low GNFB & simple CFA Amp. driving high efficiency (96 db or more ) and light load (16 ohm or more ) loudspeakers .?
Best Regards !
After replacing the transistors Q11, Q14
http://s017.radikal.ru/i419/1401/f1/1ea1368c19f6.png
best regards
Petr
http://s017.radikal.ru/i419/1401/f1/1ea1368c19f6.png
best regards
Petr
Hi banat!
The loudspeakers were 8Ohm/92dB/W, two way floor-stand with SAL (hungarian manufacturer) speakers in bass reflex enclosure. The amplifier had 30W/8ohm output power only. If I tried without any NFB it sounded simply good, very close to Mission Cyrus III's character. Applying of 8-10 dB of feedback, the little amp got wings and shown enormous dynamic with little bit rounded highs and very very smooth mids (though bit lack of details (?)) and extremely smooth, flowing character.
Best Regards!
Egra
Is that your DIY CFA Amp was based on ` Canopus ` topology ? , or on some variant of Mr.Gabor ( Gaborbella ) generic VSSA Amp ? , or was something else ? ,
BTW , I remember those old original SAL loudspeaker as very good performer ! , but must say that even today I use some vintage - Videoton - 10`` & 12 `` / 8 ohm bass speaker inside of my second audio system with great success !
And yes , advantage of DIY of simple CFA circuits is possibility of fine tuning of Amp linearity before any amount of GNFB was applied .
Hi banat! It was Canupos topology with self designed PCB. Although I never noticed any instability issue, some builder reported this. The circuit was published by the founder of Heed Audio in a diy magazine. Though he described the sound of this amp as close to the "straight wire with gain" it was manufactured for a few years only. Let me quote Paul Messenger's words about Canopus' sound (hi-fi+ Issue 30):
"...have notably coherent tonal and dynamic structure and architecture. I was spinning a familiar favourite, the Grateful Dead’s acoustic Reckoning set, and found myself sucked into focusing on Garcia’s guitar much more intently than usual, and my partner actually started dancing along as she came into the room." - I felt the same...
I'll send a PM soon
regards
egra
Stirring the pot
I don't need the so much applauded 'current on demand' feature of a CFA input stage. Without precautions, it only pushes the TIS into class B. In a well designed VFA front-end, the ratio of the LTP AC versus DC current can be kept so small that the tanh distortion is virtual zero. In the Super TIS, for example, the AC current is only 3ppm of the LTP DC current at 100kHz and full power. So there is lots of current in reserve. To me, this 'current on demand' feature of a CFA is a non-issue.
Cheers, E.
I don't need the so much applauded 'current on demand' feature of a CFA input stage. Without precautions, it only pushes the TIS into class B. In a well designed VFA front-end, the ratio of the LTP AC versus DC current can be kept so small that the tanh distortion is virtual zero. In the Super TIS, for example, the AC current is only 3ppm of the LTP DC current at 100kHz and full power. So there is lots of current in reserve. To me, this 'current on demand' feature of a CFA is a non-issue.
Cheers, E.
How would you design your best effort CFA topology?? --- using its strengths.
Thx-RNMarsh
Thx-RNMarsh
Last edited:
Richard,
There has always been the case of those who have book knowledge and those who have that and practical experience. I have seen it so many times, those first out of college who think they have it all down, they finished school and think that is it. But that is almost never the case, now you really have to start learning to apply the knowledge and find out how much you really have no idea about. I have seen some smart engineers, book wise and mathematically, say, I can analysis this problem, put it in my simulation program and predict the outcome. That seldom works, might get you close but no cigar. They will scratch their heads and say but the math backs me up, but the actual results don't. They fail to see that there are variables that are not linear or factors that are left out of the analysis. This is how I look at all this electronics, I may understand the basic concepts of what is going on, but I know for a fact that I don't understand the nuances of what isn't obvious. This is why I collaborate on certain things I do, because I know I don't know everything, just enough to get me in trouble sometimes! Other things I do know others come to me and ask the questions, it is give and take. Those who want to believe that all they need is a degree and book knowledge will be bitten in the rear when the proverbial S**t hits the fan.
There has always been the case of those who have book knowledge and those who have that and practical experience. I have seen it so many times, those first out of college who think they have it all down, they finished school and think that is it. But that is almost never the case, now you really have to start learning to apply the knowledge and find out how much you really have no idea about. I have seen some smart engineers, book wise and mathematically, say, I can analysis this problem, put it in my simulation program and predict the outcome. That seldom works, might get you close but no cigar. They will scratch their heads and say but the math backs me up, but the actual results don't. They fail to see that there are variables that are not linear or factors that are left out of the analysis. This is how I look at all this electronics, I may understand the basic concepts of what is going on, but I know for a fact that I don't understand the nuances of what isn't obvious. This is why I collaborate on certain things I do, because I know I don't know everything, just enough to get me in trouble sometimes! Other things I do know others come to me and ask the questions, it is give and take. Those who want to believe that all they need is a degree and book knowledge will be bitten in the rear when the proverbial S**t hits the fan.
Waly,
I would like to see one instance where I have proposed a circuit or corrected anyone's electronics on this forum. I have just said I can't and wouldn't do that, I am only here to read and learn and the occasional comments I might make are not on the electronic circuit side of things. I work on the mechanical side of things and that is what I was referencing in my comments. Now you want to build a loudspeaker or even a UAV and I can talk to you or many things about plastics, but I won't argue about circuit design besides my comment that book knowledge doesn't always tell the whole story. Doesn't mean I can't ask a question to understand what people are talking about.
I would like to see one instance where I have proposed a circuit or corrected anyone's electronics on this forum. I have just said I can't and wouldn't do that, I am only here to read and learn and the occasional comments I might make are not on the electronic circuit side of things. I work on the mechanical side of things and that is what I was referencing in my comments. Now you want to build a loudspeaker or even a UAV and I can talk to you or many things about plastics, but I won't argue about circuit design besides my comment that book knowledge doesn't always tell the whole story. Doesn't mean I can't ask a question to understand what people are talking about.
. . . I think it's you who we are waiting to see data from. And no, some CMOS circuit running on sparrow fart current doesn't count.
So, show us something.
So, show us something.
Without taking the PSRR or thermal stability into consideration , the 2 simplest
circuits ... 1 VFA , 1 CFA.
The VFA would most likely be a single differential with a bootstrapped
or current sourced VAS. If bootstrapped, the extra transistor could be a LED CCS
(for the LTP).
There .. 4 whole devices. 😀
The simplest CFA would be the VSSA ... 2 for the input pair / 2 for the VAS.
Again , 4 devices with a number of resistors and capacitors for support.
With 4 devices each , the VFA is a "toy" .... .05 -.1 % THD , no Superior PSRR.
On the other hand , a 4 device CFA (like the VSSA) ... especially if
crudely regulated , can provide low double digit PPM.
Performance wise , at this absolute minimum ... the CFA is WAY ahead
of the VFA. I'm a "VFA man" ... but I admit this. 😱
With an 8-10 device CFA/VFA "shootout" , the field is leveled. One topology
with slightly lower THD ... one with a faster response. They actually tend
to "merge" (performance wise) at this device level.
OS
circuits ... 1 VFA , 1 CFA.
The VFA would most likely be a single differential with a bootstrapped
or current sourced VAS. If bootstrapped, the extra transistor could be a LED CCS
(for the LTP).
There .. 4 whole devices. 😀
The simplest CFA would be the VSSA ... 2 for the input pair / 2 for the VAS.
Again , 4 devices with a number of resistors and capacitors for support.
With 4 devices each , the VFA is a "toy" .... .05 -.1 % THD , no Superior PSRR.
On the other hand , a 4 device CFA (like the VSSA) ... especially if
crudely regulated , can provide low double digit PPM.
Performance wise , at this absolute minimum ... the CFA is WAY ahead
of the VFA. I'm a "VFA man" ... but I admit this. 😱
With an 8-10 device CFA/VFA "shootout" , the field is leveled. One topology
with slightly lower THD ... one with a faster response. They actually tend
to "merge" (performance wise) at this device level.
OS
Seems reasonable. Do the listening shoot out. Does the faster CFA sound better than the slightly lower thd? Does an even faster CFA increase the difference? Or no difference noticed. Is the listening difference greater with the simpler circuits or the more complex circuits?
Thx-RNMarsh
This is not a salespeech.
It is 100% up to the house keeping .
We did a listening session yesterday.
Tssa (a variant of the vssa but enhanced) and the mirand a2 with the diamond buffer i posted here.
Sound stage is identical but the mirand a2 showed a lot more air and room In the Music .
From This view i see no reason to diss Any of the topologies.
Good info. We have no intention of dissing any other topology... we want to know what characteristics the CFA has -- in sim and in listening.
Then see what part of the topology or parameter of the topology is responsible for the sound difference. Can you talk to these points for us?
Thx-RNmarsh
Then see what part of the topology or parameter of the topology is responsible for the sound difference. Can you talk to these points for us?
Thx-RNmarsh
Last edited: