I have a good PSU 2x46V. Do you think symasym can handle the voltage for a total around 100W RMS or needs heavy modifications (more output transistors etc)?
Mike what do you think?
Thanks in advance.
Mike what do you think?
Thanks in advance.
Symasym and relativity theory...
The following is not a joke.
I went to a watch repair shop today. I explained to the kind young lady that my watch gains or loses about 10' every 12 hours randomly. And not every day. Only last week. She asked me (looking at me suspiciously, I can say, straight at the eyes) if I had done anything "strange" last week. After I asked her what she meant with the word "strange" she explained that she meant if I was exposed to large electromagnetic fields, near big transformers for example. I said no, and decided to keep my watch for some more time, to see if the "time shift" happens again. Just as I walked out of the shop, my mind flashed! Symasym!
Mike, Pavel, is it possible that symasym's oscillations at the frequency you reported (6.4 MHz) may have affected my electronic watch, sitting for some time near the amplifier, during last week's experiments? Just curious....
If it is so, perhaps symasym distorts time, as well, we should check it😉
The only problem is we have to calculate the exact values of Cf for the needed time shift every time (a variable capacitor perhaps?)
The following is not a joke.
I went to a watch repair shop today. I explained to the kind young lady that my watch gains or loses about 10' every 12 hours randomly. And not every day. Only last week. She asked me (looking at me suspiciously, I can say, straight at the eyes) if I had done anything "strange" last week. After I asked her what she meant with the word "strange" she explained that she meant if I was exposed to large electromagnetic fields, near big transformers for example. I said no, and decided to keep my watch for some more time, to see if the "time shift" happens again. Just as I walked out of the shop, my mind flashed! Symasym!
Mike, Pavel, is it possible that symasym's oscillations at the frequency you reported (6.4 MHz) may have affected my electronic watch, sitting for some time near the amplifier, during last week's experiments? Just curious....
If it is so, perhaps symasym distorts time, as well, we should check it😉
The only problem is we have to calculate the exact values of Cf for the needed time shift every time (a variable capacitor perhaps?)
Hi Dimitris !
About your watch... 😀 Yes, it is possible that if the watch is not shielded against EMI that symasym made it go wrong... I doubt that symasym shifts time, but if it does i will return with a functional stargate next week !
I think with a cfb of 100pF you can make your watch go backwards ! 😉
Nice to hear that with the reduced cfb your symasyms work !
About the 46volts, NO ! Definitely no, because the bc550c or mpsa18 have 45v rating, plus the CM-swing they will exceed their maxratings and blow, taking the rest of the amp with them...
Symasym was designed for 36v, not higher, 40v okay, but not more !
For 46v symasym would need some changes, you could simply use bc546 (65v rating) as input devices, but still, symasym was not designed for that. With the bc546 in the input it will not blow, but i am not sure about other effects. With this voltage you should not connect 4ohm speakers, only 8ohms. At least, all other devices should withstand this voltage.
BTW, the difference between 50watts and 100watts is ~3db, the threshold of what the human ear can detect, you would barely notice the difference...
Mike
About your watch... 😀 Yes, it is possible that if the watch is not shielded against EMI that symasym made it go wrong... I doubt that symasym shifts time, but if it does i will return with a functional stargate next week !
I think with a cfb of 100pF you can make your watch go backwards ! 😉
Nice to hear that with the reduced cfb your symasyms work !
About the 46volts, NO ! Definitely no, because the bc550c or mpsa18 have 45v rating, plus the CM-swing they will exceed their maxratings and blow, taking the rest of the amp with them...
Symasym was designed for 36v, not higher, 40v okay, but not more !
For 46v symasym would need some changes, you could simply use bc546 (65v rating) as input devices, but still, symasym was not designed for that. With the bc546 in the input it will not blow, but i am not sure about other effects. With this voltage you should not connect 4ohm speakers, only 8ohms. At least, all other devices should withstand this voltage.
BTW, the difference between 50watts and 100watts is ~3db, the threshold of what the human ear can detect, you would barely notice the difference...
Mike
Upupa Epops said:
??? I use these for vas, but for input ? They have only hfe of 150, quite lousy compared to the hfe = 1000 of the mpsa18...
Mike
It's enough...don't take only absolute value...when I was starting, on the market was only germanium transistors with beta cca 30-40... 😱)
The Zetex pair ZTX694B and ZTX795A might also work well as the input. I've used them on some restorations. hfe 300-400 on the ones i measured iirc???? 120 and 140 Vceo.
Hey MikeB,
I found this BJT :
FAIRCHILD KSC2784FBU
what do you think about it ?
Datasheet KSC2784FBU
Some Data:
MikeB said:
I found this BJT :
FAIRCHILD KSC2784FBU
what do you think about it ?
Datasheet KSC2784FBU
Some Data:
Attachments
Hi Uwe, this Fairchild device does not look bad, especially the Cob of 1.6pF ! Okay, mpsa18 has 1.7pF and ft=170 at 1ma... still hard to beat except the max vce !
I think, unless the max vce of 45v is no problem, the mpsa18 is hard to beat...
Mike
I think, unless the max vce of 45v is no problem, the mpsa18 is hard to beat...
Mike
Re: Everything seems ok with symasym
Dimitris,
I think you can set the Iq back to higher values now, if you want. I reviewed symasym at Iq = 150 mA, the reason was lower THD at 5kHz. For Iq about 50 mA, the THD at high frequencies was about twice higher, measured into 4 ohms.
dtrif said:
Dimitris,
I think you can set the Iq back to higher values now, if you want. I reviewed symasym at Iq = 150 mA, the reason was lower THD at 5kHz. For Iq about 50 mA, the THD at high frequencies was about twice higher, measured into 4 ohms.
Despite of loosing power, i am using 180 ohms resistor at rails
Listening, i perceive that sound turns better during dinamic peaks...distortion there, listenable distortion, even when volume too much high, was lower...... resulting in more clean dinamics.
Also using 38 Volts each rail.
But those details, really, are only details, as the amplifier works fine without those small modifications....my feedback capacitor was always Silver Mica and 12 picofarads!
Input electrolitic condenser, are 220uf bypassed with 100N.
Well, those things may be nice to someone try...as do not represent so big modifications.
One another unit is using not Sankens, it is using TIP2055 and TIP3055, very slow units, having 4 pairs of identical gain...emitter resistor are small (0.22) and will result in much less...hehehehe.
This is only for bass....it has an input filter, yeah!...those dirty analog ones!!!...but i am having 1 hertz with 50 RMS....watching speaker go and return very slowly.. at 1 Kilohertz i could measure 137 watts unclipped..7 amperes the speaker fuse... 45 Volts simetrical supply..transistors not exploding because supply are loosing voltage when drained hardly.
Glasses are shaking here!...symassym loves 25 Hertz...it pumps whole power....full throttle guys!....
My modifications were informed to Michael, but i told once and did not repeat, as i do not like to discuss those things...i think people have to do it if have curiosity, and evaluate with their own ears or instruments..that's the only way people will be convinced.
The Symassym that operates with Sankens and 38 Volts sounds better than the bigger power unit.... as highs are more detailed and present....the other one are not reproducing highs
Symassym is very interesting...very nice, including using poor transistors too!
regards,
Carlos
Listening, i perceive that sound turns better during dinamic peaks...distortion there, listenable distortion, even when volume too much high, was lower...... resulting in more clean dinamics.
Also using 38 Volts each rail.
But those details, really, are only details, as the amplifier works fine without those small modifications....my feedback capacitor was always Silver Mica and 12 picofarads!
Input electrolitic condenser, are 220uf bypassed with 100N.
Well, those things may be nice to someone try...as do not represent so big modifications.
One another unit is using not Sankens, it is using TIP2055 and TIP3055, very slow units, having 4 pairs of identical gain...emitter resistor are small (0.22) and will result in much less...hehehehe.
This is only for bass....it has an input filter, yeah!...those dirty analog ones!!!...but i am having 1 hertz with 50 RMS....watching speaker go and return very slowly.. at 1 Kilohertz i could measure 137 watts unclipped..7 amperes the speaker fuse... 45 Volts simetrical supply..transistors not exploding because supply are loosing voltage when drained hardly.
Glasses are shaking here!...symassym loves 25 Hertz...it pumps whole power....full throttle guys!....
My modifications were informed to Michael, but i told once and did not repeat, as i do not like to discuss those things...i think people have to do it if have curiosity, and evaluate with their own ears or instruments..that's the only way people will be convinced.
The Symassym that operates with Sankens and 38 Volts sounds better than the bigger power unit.... as highs are more detailed and present....the other one are not reproducing highs
Symassym is very interesting...very nice, including using poor transistors too!
regards,
Carlos
I have added several comments on Slew Rate to the review:
http://web.telecom.cz/macura/review.htm
Erratum: for short moment, there was an error in the page. The correct SR is 24V/us.
http://web.telecom.cz/macura/review.htm
Erratum: for short moment, there was an error in the page. The correct SR is 24V/us.
Thanks for the outstanding thread guys. It's been a terrific learning experience for me, and my first discreet ss amp. Michael dreamt it up, Carlos egged him on and got me and a bunch of others sucked in, and Pavel gave it a professional engineering review and tightened it all up. We now have a fine sounding amp that is robust and can be built inexpensively. I'll build another pair, then maybe give Graham's amp a shot. That one intrigues me.
BTW Pavel, If you ever unload your music collection, I'll take it sight unseen. Based on your test selections, I bet you have a bunch of gems in there. And my collection is weak on classical. Patricia is a great choice for working out the system. First, she is unique and creative. Her entire ensemble are excellent musicians and are very tight (I always love that). And, they care about the craft, so they are very well recorded. Their unique percussion riffs will show weakness in resolving power too.
Sheldon
BTW Pavel, If you ever unload your music collection, I'll take it sight unseen. Based on your test selections, I bet you have a bunch of gems in there. And my collection is weak on classical. Patricia is a great choice for working out the system. First, she is unique and creative. Her entire ensemble are excellent musicians and are very tight (I always love that). And, they care about the craft, so they are very well recorded. Their unique percussion riffs will show weakness in resolving power too.
Sheldon
I can only second this!
I have followed this thread closely (although I had to do other things more urgently🙂 ) but never popped in as I can`t add anything useful to the discussion (designing amps is not truly the field where I can excel).
This is excactly what I have searched for: an inexpensive, (relatively) easy to build, great sounding, discrete Class-AB amp for active speaker projects.
Additionally I have learned quite something about amp design.
Last but not least I have really enjoyed not only the technical arguments of this great discussion but as well the "sociological aspects" 😉 .
I equally admire the different approaches, Carlos for his enthusiastic and voluptuous raves (without him this thread would have probably slipped my intention) as well as the very rational, professional and straight forward "modus operandi" of Pavel and Michael.
Many thanks to all of You guys!!
I will make this amp too. I know nothing about amplifier design but loved to follow this thread. I will make PCBs for the first time too.
With low bias this amplifier is good economically and ecologically (I find it not totally unimportant) as well as hopefully sonically too. I was looking for something like that.
All in all thanks for this thread for now.
With low bias this amplifier is good economically and ecologically (I find it not totally unimportant) as well as hopefully sonically too. I was looking for something like that.
All in all thanks for this thread for now.
This makes me very happy Cocolino, and really, as you realise
We could have a cooperative work, with reasonable respect related our differences, and three different countries could work together, translating three languages to English, three cultures could work together and we did not gave one each other any hard offense.
Yes, Pavel is competent, having strong confidence related his methods, beeing scientific and avoiding other aspects, considered a little less important.
In the reality, Michael is really in the middle...he is not exactly the scientist, and also not a dreamer alike i am.... he started with the idea to construct something cheap, good and that could beat his Yamaha, the one he considered mufled and with strange bass...he could have his goal...listening and searching for analitic explanations related wave forms, distortions and all that matter.
Well...alike you know, i do not apreciate too much instruments, but i accept they are a need, to say to us, that probably, having good chances, some amplifier will sound good....but cannot guarantee nothing, as human ears will give the last word.
Very different we are, and with something common, the audio passion, the good intention to share and not to include money in this story....wishing many people doing it and imagining their smile using it.
I think we are all very happy with this thread...observe, i am in South America...other in Germany, other in more eastern Europe...and we could do that because our forum are joining us.
I am loosing my uncle for Cancer this day.... he is already going.... a friend that learned me many things...but you are compensating...i am not so sad as i could be without you all.
Thank you Sheldon, and others that had the atention to tell my name, including me as someone that helped to realise Michael's dream, that turn my dream also, and i think Pavel's dream too.
All this proves that we can have peace, having small strikes and finding harmony, that is possible to join different people to work together, that despite our differences, no doubts...we are all brothers.
We could sit around the fire...looking into other eyes and we decide nice things that will make you smile.
This is "guaranteed!"
regards,
Carlos
We could have a cooperative work, with reasonable respect related our differences, and three different countries could work together, translating three languages to English, three cultures could work together and we did not gave one each other any hard offense.
Yes, Pavel is competent, having strong confidence related his methods, beeing scientific and avoiding other aspects, considered a little less important.
In the reality, Michael is really in the middle...he is not exactly the scientist, and also not a dreamer alike i am.... he started with the idea to construct something cheap, good and that could beat his Yamaha, the one he considered mufled and with strange bass...he could have his goal...listening and searching for analitic explanations related wave forms, distortions and all that matter.
Well...alike you know, i do not apreciate too much instruments, but i accept they are a need, to say to us, that probably, having good chances, some amplifier will sound good....but cannot guarantee nothing, as human ears will give the last word.
Very different we are, and with something common, the audio passion, the good intention to share and not to include money in this story....wishing many people doing it and imagining their smile using it.
I think we are all very happy with this thread...observe, i am in South America...other in Germany, other in more eastern Europe...and we could do that because our forum are joining us.
I am loosing my uncle for Cancer this day.... he is already going.... a friend that learned me many things...but you are compensating...i am not so sad as i could be without you all.
Thank you Sheldon, and others that had the atention to tell my name, including me as someone that helped to realise Michael's dream, that turn my dream also, and i think Pavel's dream too.
All this proves that we can have peace, having small strikes and finding harmony, that is possible to join different people to work together, that despite our differences, no doubts...we are all brothers.
We could sit around the fire...looking into other eyes and we decide nice things that will make you smile.
This is "guaranteed!"
regards,
Carlos
All that and the English language now has new word - "Explendid". Who else but Carlos coulda come up with that?
Actually, in this manner, the non-native English speakers on this forum constantly amaze me. So many write expressively in English. Carlos is an extreme example, but Cocoline, not many Americans would have thought to use "voluptuos" in the way that you did, but it's perfect.
Sheldon
Actually, in this manner, the non-native English speakers on this forum constantly amaze me. So many write expressively in English. Carlos is an extreme example, but Cocoline, not many Americans would have thought to use "voluptuos" in the way that you did, but it's perfect.
Sheldon