😀 😀
Oh Michael,
I was not interested in milliwats at all. The simulation showed that it should DC stabilize somewhere at +2V at the collector of Q12. The real world was worse, about +8V, but id did not run to supply rail, that's what surprised me. So it was possible to check currents of input stage and VAS.
Cheers,
Pavel
Oh Michael,
I was not interested in milliwats at all. The simulation showed that it should DC stabilize somewhere at +2V at the collector of Q12. The real world was worse, about +8V, but id did not run to supply rail, that's what surprised me. So it was possible to check currents of input stage and VAS.
Cheers,
Pavel
Ah yes, i think that's why similar topology is used in many opamps, with some improved cascoding and matching you get DC close to 0v in openloop operation !
This should be one of the mainreasons why symasym does not create turn on/off thumps, it simply does not know how to create big DC... 😀
And, obviously, you did a good job with matching devices !
With openloopgain of 1:32000 you should get ~0.25mv DC offset when closing loop... 🙂
(If you match drivers equally good)
Mike
This should be one of the mainreasons why symasym does not create turn on/off thumps, it simply does not know how to create big DC... 😀
And, obviously, you did a good job with matching devices !
With openloopgain of 1:32000 you should get ~0.25mv DC offset when closing loop... 🙂
(If you match drivers equally good)
Mike
BTW - what happens if one of the fuses F1, F2 blows and speakers are connected? How about protecting diode somewhere in supply rail.
PMA said:
If negative fuse blows, the amp goes completely dead (accidently tested), and sims show DC below 1v if positive fuse blows. (Dont' have a bottle of wine and then do measurings...)
But, your concern is about caps getting reverse voltage ?
Mike
Yes, but not only caps. The information you have provided is very useful, greatly appreciated.
Do you assume to put the amp in regular production?
Pavel
Do you assume to put the amp in regular production?
Pavel
PMA said:
I have no plans regarding that, too much work, it will need support, guarantees and so on...
And, some of the software used was not bought, it would be wrong to make profit now.
But, if more guys are satisfied, some kit might be interesting ?
With improved PCB layout of course...
Mike
Got this thing working
Hello folks,
This morning I got the amp working fine.
Michael has been a great help and he was not (hopefully) bothered by my e-mail harassment.
I will post the listening impressions soon. I´ll have to wait better components from Germany to give a better evaluation.
My wife is going to kill me soon for spending a vacation with amplifiers
Jarno
Hello folks,
This morning I got the amp working fine.
Michael has been a great help and he was not (hopefully) bothered by my e-mail harassment.
I will post the listening impressions soon. I´ll have to wait better components from Germany to give a better evaluation.
My wife is going to kill me soon for spending a vacation with amplifiers
Jarno
Jarka.... big fat Charlie worked as an animal during Michael's developments...i will
be happy if you send me your evaluation...better to post clear to all of us...if bad, we will find solution...if good, we will reach more happyness..... problems may happen, as we use do make mistakes assembling....the amplifier was hardly tested.... it is beeing under listening daily.
It may be good if everything is in order.
Michael is busy.... normally he eat hamburgers with some keyboard parts, as he is working fast and all time long..sleeping in his office...having shower inside his company.. he will not forward your data to me...because the one is German!..if you not tell him, clearly, and without any doubts, that you want him to send me a "forward" of your mail...he will never do that.
His mind...ancient Germanic mind.... work following instructions...this yes...this no!...ahahahahahhaa!
He is my friend..we use to go kidding one each other.... he also let me know that i am some kind of bad educated "barbarian"
hehe.
Good friend that chucrute....full or rules....aaaaaagh....bahhhh!
regards,
Carlos
be happy if you send me your evaluation...better to post clear to all of us...if bad, we will find solution...if good, we will reach more happyness..... problems may happen, as we use do make mistakes assembling....the amplifier was hardly tested.... it is beeing under listening daily.
It may be good if everything is in order.
Michael is busy.... normally he eat hamburgers with some keyboard parts, as he is working fast and all time long..sleeping in his office...having shower inside his company.. he will not forward your data to me...because the one is German!..if you not tell him, clearly, and without any doubts, that you want him to send me a "forward" of your mail...he will never do that.
His mind...ancient Germanic mind.... work following instructions...this yes...this no!...ahahahahahhaa!
He is my friend..we use to go kidding one each other.... he also let me know that i am some kind of bad educated "barbarian"
hehe.
Good friend that chucrute....full or rules....aaaaaagh....bahhhh!
regards,
Carlos
Attachments
Hôhôhô said my friend Herman... Gonna have partie this weekend...barbecue!
We are already making party here....herman loves Beer...he came from Germany last year.... "unt hee spikes gut portugueeeze!"
We gonna drink and eat very much...as amplifier proved not to explode!...ahahahaahahahha...for a while!
He Miky!.... Pavel is terrible.!.... he fast found our beloved oscilation....only first time.... it will go away...magic!...ahahahaha!
See the image, after our party...because Pavel will say good things...if not...we already have the guilty....FEVER...he has fever!!!!
ahahahaha!
regards,
Carlos
We are already making party here....herman loves Beer...he came from Germany last year.... "unt hee spikes gut portugueeeze!"
We gonna drink and eat very much...as amplifier proved not to explode!...ahahahaahahahha...for a while!
He Miky!.... Pavel is terrible.!.... he fast found our beloved oscilation....only first time.... it will go away...magic!...ahahahaha!
See the image, after our party...because Pavel will say good things...if not...we already have the guilty....FEVER...he has fever!!!!
ahahahaha!
regards,
Carlos
Attachments
Initial impressions
Hello folks,
In the beginning I would like to thank Herr Bittner, Carlos and PMA for keeping this thread up and running.
Without Carlos´s input I would have never been interested in this project. His style of writing and enthusiastic approach kind of sucked me in to this. Thanks a lot Carlos!!
Now to the subject:
Symasym 5 has been hooked to main main system for few hours now. I am using PMA´s audio buffer as a preamp with gain of 1.8.
First noticable thing was the increased dynamics compared to my current amp:
Especially the bass section is extremely well controlled and tight. My TL speakers certainly got more punch to the lower register.
Detailing is extraordinary good too. Midrange is very detailed and surprisingly transparent. Especially female vocals are beautiful I can almost touch Shirley Bassey while she is singing to me. Also electric guitars in Pekka Pohjola´s heavy jazz live in Japan are stunning.
I have a gut feeling that the highs are maybe a bit harsh but cannot say for sure. I got this feeling only when I am listenig saxophone.
Not the softest one I have heard still top end detail is excellent too.
Even by this short listenig session I can say for sure that The overall performance of Symasym outperforms all my previous amps. I have several different gainclones, Nad integrated and a big Yamaha integrated.
I am very satisfied with the result. There is also more to come. I have ordered some good quality caps since I have ceramics on the board now. One more thing, my drivers are mje15034/35 and the output devices are MJL4281/4302.
It seems that Herr Bittner is some sort of genius...l
See the pic: taken from my back yard few hours ago
not very funny, I am glad that I have something new to play around with.
Jarno
Hello folks,
In the beginning I would like to thank Herr Bittner, Carlos and PMA for keeping this thread up and running.
Without Carlos´s input I would have never been interested in this project. His style of writing and enthusiastic approach kind of sucked me in to this. Thanks a lot Carlos!!
Now to the subject:
Symasym 5 has been hooked to main main system for few hours now. I am using PMA´s audio buffer as a preamp with gain of 1.8.
First noticable thing was the increased dynamics compared to my current amp:
Especially the bass section is extremely well controlled and tight. My TL speakers certainly got more punch to the lower register.
Detailing is extraordinary good too. Midrange is very detailed and surprisingly transparent. Especially female vocals are beautiful I can almost touch Shirley Bassey while she is singing to me. Also electric guitars in Pekka Pohjola´s heavy jazz live in Japan are stunning.
I have a gut feeling that the highs are maybe a bit harsh but cannot say for sure. I got this feeling only when I am listenig saxophone.
Not the softest one I have heard still top end detail is excellent too.
Even by this short listenig session I can say for sure that The overall performance of Symasym outperforms all my previous amps. I have several different gainclones, Nad integrated and a big Yamaha integrated.
I am very satisfied with the result. There is also more to come. I have ordered some good quality caps since I have ceramics on the board now. One more thing, my drivers are mje15034/35 and the output devices are MJL4281/4302.
It seems that Herr Bittner is some sort of genius...l
See the pic: taken from my back yard few hours ago
not very funny, I am glad that I have something new to play around with.
Jarno
Attachments
Harsh highs
Jarno -
have you got a chance to connect an oscilloscope to the output? You probably read my comments about oscillations on my web page, I would strongly recommend to every builder to use a scope, as stability is a bit delicate thing for this amp. Oscillations lead to harsh highs.
Cheers,
Pavel
Jarno -
have you got a chance to connect an oscilloscope to the output? You probably read my comments about oscillations on my web page, I would strongly recommend to every builder to use a scope, as stability is a bit delicate thing for this amp. Oscillations lead to harsh highs.
Cheers,
Pavel
Dobry den Pavel
Yes, I read your text, unfortunately I haven´t got a scope. I think I´ll start playing around with the bias adjustment. And again unfortunately I have a standard pot for adjustmet too. It´s a real pain trying to adjust with over sensitive pot.
This has been a short evaluation time so the comment about harshness may be a little too early.
One thing I know for sure:
I need to get bigger heatsink, because this amp gets almost hot with my current one.
Jarno
Yes, I read your text, unfortunately I haven´t got a scope. I think I´ll start playing around with the bias adjustment. And again unfortunately I have a standard pot for adjustmet too. It´s a real pain trying to adjust with over sensitive pot.
This has been a short evaluation time so the comment about harshness may be a little too early.
One thing I know for sure:
I need to get bigger heatsink, because this amp gets almost hot with my current one.
Jarno
Hi Jarno,
I recommend to set Iq of output stage no higher than 30mA, for stability margin. You just measure voltage across R27 by DVM. Then:
Iq = V(R27)/R27 = V(R27)/0.22
So you should read about 6.6mV on DVM display.
Maybe Michael has another recommendation?
I recommend to set Iq of output stage no higher than 30mA, for stability margin. You just measure voltage across R27 by DVM. Then:
Iq = V(R27)/R27 = V(R27)/0.22
So you should read about 6.6mV on DVM display.
Maybe Michael has another recommendation?
Dobry den guys!.... i once had this harsh too...and appear not constantly, so, Pavel
Words and your words makes sense....my prefered unit is the model 4....and the difference...the especial and important difference is that my model use a Miller Capacitor up...at the second voltage amplifier you have at up and rigth side of your board...positive half cicle..
The calculated optimum value was 68 picofarads...i am satisfied with 33 picofarads, and did not hear harshing sound anymore.
Those harshes..... are not constant, well, in my case happened once or twice during entire music.
Mike used to bias with 100 miliamps.... 60 miliamps to the output...if i can remember...and the resting miliamps to input and voltage amplifier.
But here, there are a friendly, democratic, fair and peacefull disagreement between dear Mike and I...he prefer the soft tones from Symassym 5..... i prefer to use my unit Symassym 4...made both, and compared.... i prefer the more brigth trebles of Symassym 4....if this is a result of distortion, ringing, oscilation or something awfull alike those words...hehe...i will have to accept that i love those things!
The first one that told about that sometimes appear some harsh was the Baron of Saint Ivy, a Portuguese Enginner that live in Fredon, New Jersey, USA.... i cannot ask him about, because i think he cannot move his lips...may be frozzen now!
Play "Brave heart" movie theme....put all volume up...and protect your fragile things against vibration...ahahahaha!
But really....well...really, really, really,.... what a good golden years.... was hard to discover that, to perceive that, we took good time to conclude that.
regards,
Carlos
Words and your words makes sense....my prefered unit is the model 4....and the difference...the especial and important difference is that my model use a Miller Capacitor up...at the second voltage amplifier you have at up and rigth side of your board...positive half cicle..
The calculated optimum value was 68 picofarads...i am satisfied with 33 picofarads, and did not hear harshing sound anymore.
Those harshes..... are not constant, well, in my case happened once or twice during entire music.
Mike used to bias with 100 miliamps.... 60 miliamps to the output...if i can remember...and the resting miliamps to input and voltage amplifier.
But here, there are a friendly, democratic, fair and peacefull disagreement between dear Mike and I...he prefer the soft tones from Symassym 5..... i prefer to use my unit Symassym 4...made both, and compared.... i prefer the more brigth trebles of Symassym 4....if this is a result of distortion, ringing, oscilation or something awfull alike those words...hehe...i will have to accept that i love those things!
The first one that told about that sometimes appear some harsh was the Baron of Saint Ivy, a Portuguese Enginner that live in Fredon, New Jersey, USA.... i cannot ask him about, because i think he cannot move his lips...may be frozzen now!
Play "Brave heart" movie theme....put all volume up...and protect your fragile things against vibration...ahahahaha!
But really....well...really, really, really,.... what a good golden years.... was hard to discover that, to perceive that, we took good time to conclude that.
regards,
Carlos