Sheldon soon will came with his evaluation to our forum, this man spend all his life
Searching for perfect waves, not only surfing but also listening to audio appliances..... his spare time is dedicated to family and those things i told you.
You can evaluate fast, observing the work the man done, that he is someone that search for the best, and worked hard, with the best material que could find, as the wood he is using is precious and a thick block beeing hand polished with natural wax.
The anodised aluminium is thick and expensive, appearance is Germanic, pretty and strong...capable to resist to a Catterpillar going over....made to last, and i am sure, this amplifier will produce good sound, that will compete with the better amplifiers produced those next 10 years to came.
This amplifier is guaranteed!..... or your satisfaction or i will use dress and cross main street nude.....and can call me "Charlotte"...some not male version of Charles.
If i was selling this unit...i could say. "Your full satisfaction or money back guaranteed!"
I will repeat.... full satisfaction, in my point of view...i put my name and honor to defend Aksa, Symasym and GEM and JLH....no other ones i could listen, and apreciated so much, to dress my Knight armoured plates and to figth for those amplifiers honor!
I remenber my friends that i am not an EE, but i have listening practice, of A to B comparison for 45 years long...i am not better than nobody...but related audition, i can be so good as the best ones to evaluate sound...as i did not more than work to maintain family and all spare time dedicated to that.... deep guaranteed equipments, where Aksa is impossible to destruct..reliable....Symassym has incredible dinamics...and GEM produce pretty voices and bass.....each one of them with their best characteristics...i have all them working, everyday listening, re-evaluating always, as i cannot stop to do that...just cannot.
Mr. Sheldon may be an Enginneer.... experienced he may be, and humble too much to open his mouth about that...but if he want to not publish his experience, no problem to me..but the heatsink size, the aluminium thick blocks to delay overheat, are showing me that we may have a teacher there.
The aluminium panels Sheldon is using can dissipate better one side than the other...but you could see clever convection apperture up, exactly where air stream is going up...this is experience..only time doing can give this, so, he may be old constructing things, may have stock of amplifiers done.... the man is humble and enclose into something alike a Shell..... his name...those life accidents that i do not believe entirely as accidents.... Shell done.
As Well done is a fair and fast moderator ....those names are not accident....mine means under watter diver....i can stay around 3 minutes without move under water, and i love to be under water, do not like to swim surface.
I am impressed as he calculated exactly to have 8 ohms dissipation...and average power during 4 ohms audition...having 20 percent more dissipation than needed...this is experience... all peaks will be hold by thick aluminium, that will produce some delay in heat transmission, when average power will be liberated into the air...wonderfull....my deep respects Doctor Sheldone.
Do you know what i really think observing his work.....this man may had designed Marantz....i can see things that i observed in Marantz.
Observe the thick aluminium block...exactly where the iron transformer Holder/Shield cannot block magnetic field.... see that aluminium thickness is there to avoid disturb the amplifier input...the choice of good material in the input...very good!
I ensure you dear Sheldon, you will kiss this amplifier everyday you switch this units on!
Introduce metal instruments.... play bells, listen at noises alike rain.... thunder...birds singing.....people clapping...piano playing and you will be crazy for it...the way i am!
Can i have this Ohana music Sheldon?
nanabrother@yahoo.com
Please Sheldon...be bad.... be terrible.... be awfull...tell us all defects.... search for subtile strange things...find for radio frequency detected (i could find.... too much hi frequency transistors.... more problem than solution...but a couple of milivolts only).... try to be bad with it..... and even this way i will be free to dress myself as Charlotte...as those units i said are really Goooooooood!
regards,
Carlos
Searching for perfect waves, not only surfing but also listening to audio appliances..... his spare time is dedicated to family and those things i told you.
You can evaluate fast, observing the work the man done, that he is someone that search for the best, and worked hard, with the best material que could find, as the wood he is using is precious and a thick block beeing hand polished with natural wax.
The anodised aluminium is thick and expensive, appearance is Germanic, pretty and strong...capable to resist to a Catterpillar going over....made to last, and i am sure, this amplifier will produce good sound, that will compete with the better amplifiers produced those next 10 years to came.
This amplifier is guaranteed!..... or your satisfaction or i will use dress and cross main street nude.....and can call me "Charlotte"...some not male version of Charles.
If i was selling this unit...i could say. "Your full satisfaction or money back guaranteed!"
I will repeat.... full satisfaction, in my point of view...i put my name and honor to defend Aksa, Symasym and GEM and JLH....no other ones i could listen, and apreciated so much, to dress my Knight armoured plates and to figth for those amplifiers honor!
I remenber my friends that i am not an EE, but i have listening practice, of A to B comparison for 45 years long...i am not better than nobody...but related audition, i can be so good as the best ones to evaluate sound...as i did not more than work to maintain family and all spare time dedicated to that.... deep guaranteed equipments, where Aksa is impossible to destruct..reliable....Symassym has incredible dinamics...and GEM produce pretty voices and bass.....each one of them with their best characteristics...i have all them working, everyday listening, re-evaluating always, as i cannot stop to do that...just cannot.
Mr. Sheldon may be an Enginneer.... experienced he may be, and humble too much to open his mouth about that...but if he want to not publish his experience, no problem to me..but the heatsink size, the aluminium thick blocks to delay overheat, are showing me that we may have a teacher there.
The aluminium panels Sheldon is using can dissipate better one side than the other...but you could see clever convection apperture up, exactly where air stream is going up...this is experience..only time doing can give this, so, he may be old constructing things, may have stock of amplifiers done.... the man is humble and enclose into something alike a Shell..... his name...those life accidents that i do not believe entirely as accidents.... Shell done.
As Well done is a fair and fast moderator ....those names are not accident....mine means under watter diver....i can stay around 3 minutes without move under water, and i love to be under water, do not like to swim surface.
I am impressed as he calculated exactly to have 8 ohms dissipation...and average power during 4 ohms audition...having 20 percent more dissipation than needed...this is experience... all peaks will be hold by thick aluminium, that will produce some delay in heat transmission, when average power will be liberated into the air...wonderfull....my deep respects Doctor Sheldone.
Do you know what i really think observing his work.....this man may had designed Marantz....i can see things that i observed in Marantz.
Observe the thick aluminium block...exactly where the iron transformer Holder/Shield cannot block magnetic field.... see that aluminium thickness is there to avoid disturb the amplifier input...the choice of good material in the input...very good!
I ensure you dear Sheldon, you will kiss this amplifier everyday you switch this units on!
Introduce metal instruments.... play bells, listen at noises alike rain.... thunder...birds singing.....people clapping...piano playing and you will be crazy for it...the way i am!
Can i have this Ohana music Sheldon?
nanabrother@yahoo.com
Please Sheldon...be bad.... be terrible.... be awfull...tell us all defects.... search for subtile strange things...find for radio frequency detected (i could find.... too much hi frequency transistors.... more problem than solution...but a couple of milivolts only).... try to be bad with it..... and even this way i will be free to dress myself as Charlotte...as those units i said are really Goooooooood!
regards,
Carlos
Attachments
The external view.... hummmm this wood block...hummmm ...pretty!
Will be nice....hummm, put lamps over it..... maybe some color at nigth...well....my God!....having wine with a good and beloved woman.... eating Schrimps toasted with garlic....listening Ohana with Symasym....well..... something we can have, Paradise in earth.
regards,
Carlos
Will be nice....hummm, put lamps over it..... maybe some color at nigth...well....my God!....having wine with a good and beloved woman.... eating Schrimps toasted with garlic....listening Ohana with Symasym....well..... something we can have, Paradise in earth.
regards,
Carlos
Attachments
Re: Sheldon soon will came with his evaluation to our forum, this man spend all his life
Probably proper construction /wiring, grounding and shielding/ would help, this won't necessarilly be circuit problem, but builder's ...
And RF filter in the beginning of a signal path ..
destroyer X said:
Probably proper construction /wiring, grounding and shielding/ would help, this won't necessarilly be circuit problem, but builder's ...
And RF filter in the beginning of a signal path ..
Re: The external view.... hummmm this wood block...hummmm ...pretty!
Ah Carlos, that does sound mighty fine. Thanks for shrinking those images to reasonable size. After this post I will figure out how to send you some music.
Regarding construction and cooling: The back plate is 8.3mm thick aluminum and the sides are 4.7mm and the top and bottom are 1.5mm thick. I used heat sink compound between the sides and back, which you can see in the first picture. Actually you can see it in the second picture too. You can see it as messy fingerprints. It gets all over the place if you are not careful, or hurry, as I did. I cleaned it off today. I played some music with a good amount of bass at a volume so that it wouldn't clip on the loudest passages. This was done on 8 ohm 87db speakers. It's louder than I would normally listen. After an hour or so, the back plate reaches a temperature of about 40 degrees C. My intended use is as a midbass amp in a speaker I'm building. It's 4 ohm but 96 db efficient, so the neighbors would probably complain before I have any heat issues. If I had an application where I needed more dissipation, I could add a finned radiator to top half of the back plate. Or, there's enough room to add a fan inside.
As far a sound: I was going to do a bunch of careful AB testing and report back, but I've changed my mind. I think I'll do it casually over time instead. Why? Well, it sounds darn good, and that being the case, I'd rather just listen to music. Carlos is right about the highs. There is something subtle but distinct that makes certain sounds just sing a little more. Otherwise, top to bottom, the sound is rock solid. No grain or edge at all. I compared with a chipamp I had made. That's a nice little amp and it sounds better than it has any right to, but these are in a higher league. Not just more power, but clean and tight all the way around. I also compared it to my 30watt pp tube amps. Those amps were expensive and sounded clearly superior to a lot of other high end amps I listened to before buying, both in tonal accuracy in imaging. The output transformers likely cost more than the entire symasym. With the 8ohm speakers, they are only a little behind the sysmasym in volume and are also solid top to bottom. I would not say that they are in a different league than the symasym. Between these, it would be a matter of preference. A subtle silkyness vs. a subtle touch of definition. The tube amps may have a very slight edge on imaging - maybe, but as I said, I'm not going to do intense AB study to find out. It comes down to this: These amps are very good. There is nothing that resembles a defect to my ears. From there it's personal preference for the subtle things that appeal to individuals differently.
The symasym is also very practical. I built mine with mostly components that I got at an electronics surplus store, including the ps caps. No exotic components at all. The most expensive transistors are the output units and they are about $5 each from Digikey. And I did the bare minimum for matching the transistors (two 9v batteries in series across the transistor and a 22k resistor, with base shorted to collector, measured across transistor). The power supply is as simple as can be. So you could probably tweak these for some subtle changes if you are so inclined. Maybe a few better caps here and there. The speakers I'm building will be at least tri-amped, so I didn't want to heat up the earth just to listen to music. I built these partly because, being an AB design, they only consume a few watts at idle. If I put my ear in the speaker cone, I can hear a very faint 120hz buzz, and there is no power up or power down thump. As for possible oscillation, the only way of testing I have is to put the antenna of an AM radio right next to the case or boards. I get nothing except a faint 60 cycle hum. So if there is hf oscillation, there ain't much.
The bottom line is; you have nothing to lose. Mike has designed a very fine amp. Carlos was right to guarantee it. And his threads are way more fun than any others.
Sheldon
ps. Carlos. I did lift the input ground with a 10R and isolate the input rails with 220r, as you suggested.
destroyer X said:
Ah Carlos, that does sound mighty fine. Thanks for shrinking those images to reasonable size. After this post I will figure out how to send you some music.
Regarding construction and cooling: The back plate is 8.3mm thick aluminum and the sides are 4.7mm and the top and bottom are 1.5mm thick. I used heat sink compound between the sides and back, which you can see in the first picture. Actually you can see it in the second picture too. You can see it as messy fingerprints. It gets all over the place if you are not careful, or hurry, as I did. I cleaned it off today. I played some music with a good amount of bass at a volume so that it wouldn't clip on the loudest passages. This was done on 8 ohm 87db speakers. It's louder than I would normally listen. After an hour or so, the back plate reaches a temperature of about 40 degrees C. My intended use is as a midbass amp in a speaker I'm building. It's 4 ohm but 96 db efficient, so the neighbors would probably complain before I have any heat issues. If I had an application where I needed more dissipation, I could add a finned radiator to top half of the back plate. Or, there's enough room to add a fan inside.
As far a sound: I was going to do a bunch of careful AB testing and report back, but I've changed my mind. I think I'll do it casually over time instead. Why? Well, it sounds darn good, and that being the case, I'd rather just listen to music. Carlos is right about the highs. There is something subtle but distinct that makes certain sounds just sing a little more. Otherwise, top to bottom, the sound is rock solid. No grain or edge at all. I compared with a chipamp I had made. That's a nice little amp and it sounds better than it has any right to, but these are in a higher league. Not just more power, but clean and tight all the way around. I also compared it to my 30watt pp tube amps. Those amps were expensive and sounded clearly superior to a lot of other high end amps I listened to before buying, both in tonal accuracy in imaging. The output transformers likely cost more than the entire symasym. With the 8ohm speakers, they are only a little behind the sysmasym in volume and are also solid top to bottom. I would not say that they are in a different league than the symasym. Between these, it would be a matter of preference. A subtle silkyness vs. a subtle touch of definition. The tube amps may have a very slight edge on imaging - maybe, but as I said, I'm not going to do intense AB study to find out. It comes down to this: These amps are very good. There is nothing that resembles a defect to my ears. From there it's personal preference for the subtle things that appeal to individuals differently.
The symasym is also very practical. I built mine with mostly components that I got at an electronics surplus store, including the ps caps. No exotic components at all. The most expensive transistors are the output units and they are about $5 each from Digikey. And I did the bare minimum for matching the transistors (two 9v batteries in series across the transistor and a 22k resistor, with base shorted to collector, measured across transistor). The power supply is as simple as can be. So you could probably tweak these for some subtle changes if you are so inclined. Maybe a few better caps here and there. The speakers I'm building will be at least tri-amped, so I didn't want to heat up the earth just to listen to music. I built these partly because, being an AB design, they only consume a few watts at idle. If I put my ear in the speaker cone, I can hear a very faint 120hz buzz, and there is no power up or power down thump. As for possible oscillation, the only way of testing I have is to put the antenna of an AM radio right next to the case or boards. I get nothing except a faint 60 cycle hum. So if there is hf oscillation, there ain't much.
The bottom line is; you have nothing to lose. Mike has designed a very fine amp. Carlos was right to guarantee it. And his threads are way more fun than any others.
Sheldon
ps. Carlos. I did lift the input ground with a 10R and isolate the input rails with 220r, as you suggested.
Hi !
I made some minor optimisations...
First, i added a 10ohm between signalground and powergnd:
And i connected the groundpins of the supply-caps close to the output:
(With thick and short wire)
Also you can see the 10ohm is easy to change into existing PCB. (On the lower right)
If someone is interested i can update the PCB with these changes, or redesign the layout. Anyone ?
These 2 changes came from optimizing while measuring, they reduced
the thd. Listening to it definitely confirm improved sound, it got slightly
softer and more detailed !
Mike
I made some minor optimisations...
First, i added a 10ohm between signalground and powergnd:
And i connected the groundpins of the supply-caps close to the output:
(With thick and short wire)
Also you can see the 10ohm is easy to change into existing PCB. (On the lower right)
If someone is interested i can update the PCB with these changes, or redesign the layout. Anyone ?
These 2 changes came from optimizing while measuring, they reduced
the thd. Listening to it definitely confirm improved sound, it got slightly
softer and more detailed !
Mike
Well Sheldon, the evaluation was something that i was expecting to be this way.
But i feel fine to see that Michael and I are not delirating, having more opinions like yours, we will start to believe that we could understand what is good sound...and listening to it, as Michael was changing here and there, telling me about 0.002.... and others numbers and i always asked him "A to B comparison test recording in dat, transcribed to wave and the material was download by FTP, please!"
I have not experience to evaluate numbers....i cannot, i am not capable, not able to differentiate those things.... but i could perceive because instruments helped me, that over 0.2 i start to perceive.... and 0.5 is something annoying..... 1 percent; i do not want to listen....but this was an accident, as someone bring a distortion analiser to our A to B comparison.
Me and my friends, we use to judge quality using years, listening only...of course, if you change speaker, everything can change too, if you move speakers....everything can change also......because of that, we have a reference Headphone...the Senheiser.
I thank you Sheldon, as you made a big text, giving us this gift of your acceptation of this amplifier, also considering it good...now the Guarantee is more strong, and the amplifier more valuable to forum friends, as was made by someone that did not took part in the works done since this "kid" was borning, as i did with Michael....so..... our evaluation is passionated..... but your is not!
Thank you Sheldon...but now is time to listen your amplifier., and listening it once more, it is possible that you can have others informations, as took some time to find some failure, or some characteristic that you do not apreciate... next week i will be glad if you try something to send me that special music....now relax and have fun with it.
regards,
Carlos
........................................................................................................
PMA, i was thinking that the Radio frequency i was capturing was detected by transistor junction...base to emitter junction, because i made a short in the input and the signal remains.... 5 milivolts in the Scope...not bad.
regards,
Carlos
.......................................................................................................
Michael
This modification is already made in my amplifiers, both Symassym are using this ground connection.
Also i am using 220 ohms in the rails..... yes, loosing power there, but turns more stable the input, as my supply is not so wonderfull and voltage variations can reach the input.
I am very satisfied with your amplifier...it has nothing to change in my mind...if you try to increase, check your evolution keeping one channel untouched.... to produce an A to B comparison, to have sure that modifications worked fine.
Yes, you know that!...this is just to remember.
regards,
Carlos
But i feel fine to see that Michael and I are not delirating, having more opinions like yours, we will start to believe that we could understand what is good sound...and listening to it, as Michael was changing here and there, telling me about 0.002.... and others numbers and i always asked him "A to B comparison test recording in dat, transcribed to wave and the material was download by FTP, please!"
I have not experience to evaluate numbers....i cannot, i am not capable, not able to differentiate those things.... but i could perceive because instruments helped me, that over 0.2 i start to perceive.... and 0.5 is something annoying..... 1 percent; i do not want to listen....but this was an accident, as someone bring a distortion analiser to our A to B comparison.
Me and my friends, we use to judge quality using years, listening only...of course, if you change speaker, everything can change too, if you move speakers....everything can change also......because of that, we have a reference Headphone...the Senheiser.
I thank you Sheldon, as you made a big text, giving us this gift of your acceptation of this amplifier, also considering it good...now the Guarantee is more strong, and the amplifier more valuable to forum friends, as was made by someone that did not took part in the works done since this "kid" was borning, as i did with Michael....so..... our evaluation is passionated..... but your is not!
Thank you Sheldon...but now is time to listen your amplifier., and listening it once more, it is possible that you can have others informations, as took some time to find some failure, or some characteristic that you do not apreciate... next week i will be glad if you try something to send me that special music....now relax and have fun with it.
regards,
Carlos
........................................................................................................
PMA, i was thinking that the Radio frequency i was capturing was detected by transistor junction...base to emitter junction, because i made a short in the input and the signal remains.... 5 milivolts in the Scope...not bad.
regards,
Carlos
.......................................................................................................
Michael
This modification is already made in my amplifiers, both Symassym are using this ground connection.
Also i am using 220 ohms in the rails..... yes, loosing power there, but turns more stable the input, as my supply is not so wonderfull and voltage variations can reach the input.
I am very satisfied with your amplifier...it has nothing to change in my mind...if you try to increase, check your evolution keeping one channel untouched.... to produce an A to B comparison, to have sure that modifications worked fine.
Yes, you know that!...this is just to remember.
regards,
Carlos
Sheldon, honolulu have my foot steps, i swim at Waikiki
All musics downloaded, thanks.
Pua Sadina - Great strings
Song bird - very nice too
Ike la cabana - a cried a lot
How can i keep from singing, the Godspel...the prefered one!
Have a Pinneaple juice, mixed with Watermellow....Aloha!
Thank you very much.
regards,
Carlos
All musics downloaded, thanks.
Pua Sadina - Great strings
Song bird - very nice too
Ike la cabana - a cried a lot
How can i keep from singing, the Godspel...the prefered one!
Have a Pinneaple juice, mixed with Watermellow....Aloha!
Thank you very much.
regards,
Carlos
Yes...i know that...but please!...schhhhhh!, if modern engineers discover that, they
Will feel bad.
I do not trust that convertions to digital, using sampling, and re-converting to analogue can reproduce (produce again, restore) perfectly the complex audio waves.
In my mind, something will be missed.
Pavel, you are formally invited to produce Symassym....the reason why i am sending you this public invitation, is because i am sure you will be happy with it.
And your opinnion, your conclusions could be excelent to some corrections, or, future developments.
If this amplifier was commercial, if was in production, certainly you already had received a sample for evaluation...but it is not, it is really diy with burn fingers, failures, mistakes, weekpoints and all those things.... because Michael competence or a miracle, it is sounding better than the modern comercial units...the ones you can switch off all those lamps flashing, surround magic mistery reverberations... well.... amplifier against amplifier...hummmm, will be hard to meet this unit qualities.... for instance...dynamics!..... i want to see someone to match that..... comercial units!
Of course, people like you, that has deep know how, may found something wrong here or there.
But really dear Pavel, what does it means?.... those weeknesses?.... maybe nothing, as speaker distort much more...but do not tell guys....schhhhhh!
regards,
Carlos
Will feel bad.
I do not trust that convertions to digital, using sampling, and re-converting to analogue can reproduce (produce again, restore) perfectly the complex audio waves.
In my mind, something will be missed.
Pavel, you are formally invited to produce Symassym....the reason why i am sending you this public invitation, is because i am sure you will be happy with it.
And your opinnion, your conclusions could be excelent to some corrections, or, future developments.
If this amplifier was commercial, if was in production, certainly you already had received a sample for evaluation...but it is not, it is really diy with burn fingers, failures, mistakes, weekpoints and all those things.... because Michael competence or a miracle, it is sounding better than the modern comercial units...the ones you can switch off all those lamps flashing, surround magic mistery reverberations... well.... amplifier against amplifier...hummmm, will be hard to meet this unit qualities.... for instance...dynamics!..... i want to see someone to match that..... comercial units!
Of course, people like you, that has deep know how, may found something wrong here or there.
But really dear Pavel, what does it means?.... those weeknesses?.... maybe nothing, as speaker distort much more...but do not tell guys....schhhhhh!
regards,
Carlos
Good!, even the possibility of someone skilled as you are, evaluate this amplifier.
And much better than that, post your diagnosis of problems, and suggestions to turn it more and more reliable, will be precious to me, and i think to Michael too.
I suggest him to produce....not as a Kit.....but to produce as a factory.
He is considering this possibility.
In this case, as Michael already done a hard job, and the amplifier is already reasonable developed, some critics are welcome, as may be more usefull related the idea to produce or not produce.
This amplifier need to pass over a very small gap "filtering" process...need to be aproved for the best we have in know how, the ones that do not accept ordinary amplifiers, those, will be the one, with capability, to say to us, if amplifier can pass througth a deep analisis.
In my personal opinnion, my own need, is not necessarily the same to Michael, as i think that this amplifier need someone that go with instruments together audition, with strong will, with a pre decided purpose to smash it!.....someone that is living in deep bad mood, that want to destroy the Symassym, but also have enormous know how, and courage to be fair...to show ridiculous numbers!...well, those things.
I do not believe you are this one..... but we have to find some terrible Symassym enemy, to produce that report to us, you, beeing a friend, will be more soft...conversation will be educated, you will tell.
Well!.....this number here is not so good BUT, this other one is very good.
We need something alike:
- "This number here is reasonable, BUT, cannot hide this other one awfull number!"
My friend, Sheldon already told what he is thinking about the amplifier..... well....well.... we have deep respect and a personal friendly connection between us....he knows that i am a part of that whole thing...he told that the brigth trebles have something special ..... well, this can be distortion, harshing...something that he will avoid to say probably, or, will be in doubts, because a friend....you know those things.... friends have enormous tollerance with us.
I think you could understand...when things had the chance to turn something professional, from a factory, we need Real, deep, and non compromised analisis.
I could perceived that there are some guys that seems to not apreciate me, or maybe do not like Michael..... but they did not told me clearly that.... i have the need to discover, unless one that have this feeling and together with the feeling, have also background..know how, experience!
I think you are not the one,but you have the experience, the know how, back ground...some of our needs....i have the need to discover those ones, to invite them to evaluate, because all my friends are telling me wonderfull things..... God damn that sittuation, our friends are always trying to protect us.
I will apreciate, if you really decide to produce a fast assemble...i will be deeply honored, as i respect you as having deep know how...your informs will be good...but will be not so precise, as another guy, someone not friendly.
The reality is that, when we decide to find defects we can do it... related every amplifier...why not this way?.... why BJTs in the place of FET?.... why Symetrica and not symetrical?...this way may be better!.... well...this is easy!...more difficult is to produce decent analisis, searching for failures, but with scientific aproach....defending the true, above our own needs.
regards,
Carlos
And much better than that, post your diagnosis of problems, and suggestions to turn it more and more reliable, will be precious to me, and i think to Michael too.
I suggest him to produce....not as a Kit.....but to produce as a factory.
He is considering this possibility.
In this case, as Michael already done a hard job, and the amplifier is already reasonable developed, some critics are welcome, as may be more usefull related the idea to produce or not produce.
This amplifier need to pass over a very small gap "filtering" process...need to be aproved for the best we have in know how, the ones that do not accept ordinary amplifiers, those, will be the one, with capability, to say to us, if amplifier can pass througth a deep analisis.
In my personal opinnion, my own need, is not necessarily the same to Michael, as i think that this amplifier need someone that go with instruments together audition, with strong will, with a pre decided purpose to smash it!.....someone that is living in deep bad mood, that want to destroy the Symassym, but also have enormous know how, and courage to be fair...to show ridiculous numbers!...well, those things.
I do not believe you are this one..... but we have to find some terrible Symassym enemy, to produce that report to us, you, beeing a friend, will be more soft...conversation will be educated, you will tell.
Well!.....this number here is not so good BUT, this other one is very good.
We need something alike:
- "This number here is reasonable, BUT, cannot hide this other one awfull number!"
My friend, Sheldon already told what he is thinking about the amplifier..... well....well.... we have deep respect and a personal friendly connection between us....he knows that i am a part of that whole thing...he told that the brigth trebles have something special ..... well, this can be distortion, harshing...something that he will avoid to say probably, or, will be in doubts, because a friend....you know those things.... friends have enormous tollerance with us.
I think you could understand...when things had the chance to turn something professional, from a factory, we need Real, deep, and non compromised analisis.
I could perceived that there are some guys that seems to not apreciate me, or maybe do not like Michael..... but they did not told me clearly that.... i have the need to discover, unless one that have this feeling and together with the feeling, have also background..know how, experience!
I think you are not the one,but you have the experience, the know how, back ground...some of our needs....i have the need to discover those ones, to invite them to evaluate, because all my friends are telling me wonderfull things..... God damn that sittuation, our friends are always trying to protect us.
I will apreciate, if you really decide to produce a fast assemble...i will be deeply honored, as i respect you as having deep know how...your informs will be good...but will be not so precise, as another guy, someone not friendly.
The reality is that, when we decide to find defects we can do it... related every amplifier...why not this way?.... why BJTs in the place of FET?.... why Symetrica and not symetrical?...this way may be better!.... well...this is easy!...more difficult is to produce decent analisis, searching for failures, but with scientific aproach....defending the true, above our own needs.
regards,
Carlos
Carlos,
yes I had some reservations to the results shown in the past, we have clarified that case with Michael and I believe that it has pushed the development in right direction, as Michael told me the results.
I have already started - firstly with simulation. The circuit has good perspectives IMHO. I can see slight problems with tuning of correction capacitances, especially those 330pF against ground in voltage multiplier. Also, I would probably appreciate lower value than those 100pF in the 2nd stage. This is only simulation, but shows that some problems might rise about 30 MHz approx. Have you got any experience?
Pavel
yes I had some reservations to the results shown in the past, we have clarified that case with Michael and I believe that it has pushed the development in right direction, as Michael told me the results.
I have already started - firstly with simulation. The circuit has good perspectives IMHO. I can see slight problems with tuning of correction capacitances, especially those 330pF against ground in voltage multiplier. Also, I would probably appreciate lower value than those 100pF in the 2nd stage. This is only simulation, but shows that some problems might rise about 30 MHz approx. Have you got any experience?
Pavel
Added a 10 Ohm resistor between input ANA GND and PWR GND, as mentioned by Carlos. This one must not burn, otherwise speaker damage will occur. We know this from another amp. Anti-parallel diodes of higher current rating could help. This 10 Ohm resistor may be burnt if there is an excessive ground current between input and power gnd.
Re: Good!, even the possibility of someone skilled as you are, evaluate this amplifier.
There is a subtle something there but, at least with my limited experience so far, it doesn't seem harsh to me. My wife, who isn't an audiophile but merely tolerates my latest hobby, said that the amps sounded "clearer" than my other amps. To me, certain percussion sounds, that were always there in the background, come out just a bit more. It's actually curious to me that I would even notice, because my hearing falls off fast after about 8-10 khz. I think there is something to the notion that the effect of frequency response well outside our hearing range can be detected in the context of full range sound. I wouldn't rule out performance in the midrange or bass as affecting our perception of high frequencies either.
Sheldon
destroyer X said:
There is a subtle something there but, at least with my limited experience so far, it doesn't seem harsh to me. My wife, who isn't an audiophile but merely tolerates my latest hobby, said that the amps sounded "clearer" than my other amps. To me, certain percussion sounds, that were always there in the background, come out just a bit more. It's actually curious to me that I would even notice, because my hearing falls off fast after about 8-10 khz. I think there is something to the notion that the effect of frequency response well outside our hearing range can be detected in the context of full range sound. I wouldn't rule out performance in the midrange or bass as affecting our perception of high frequencies either.
Sheldon
Hi !
Phew, many responses !
First, big thanks to Sheldon for the evaluation, makes me proud that symasym can at least keep up
with your tubeamps ! Also for me, the power is way enough for serious listening or to bug neighbors !
And i am very reliefed that you are pleased with it !
Yes, simple circuit without too exotic parts was one of my priority goals, and having no turn on/off thump
is simply a must for me. I do not like having to add protectionrelays afterwards...
Uncolorized/natural sound was also top priority !
I am quite sure that the amp is stable, the scope shows 2mv RF-stuff, but no matter if it is turned on or off...
If there would be an instability, it should have shown up with the squarewavetest.
And, very nice job with the cases ! And yes, symasym loves percussions !
Anatech, why not trying, it is not too expensive and you might have most parts already...
I have no site or webpage yet, all plans/instructions/datas are spread over the whole thread, maybe i should
collect them all and make up a nice html ?
Which japanese transistors do you want to try ? sc2240/sa970 ?
I am not sure what happens if the 2n5551/5401 are substituted by devices with more gain, no idea...
PMA, the boardfiles on page 22 are the latest, the boards i use are a direct predecessor, until then i only
made minor changes, nothing that would be critical if my brain is still functional...
The traces on the upper layer are some "misuse" by me to easily implement wirejumpers.
This should only be a problem when giving these files into industrial production.
I have not etched the very latest version, but it is extremely unlikely that they have an error.
Thanks for the tip with the 10ohms, it would be really bad if they burn up, do you think a 1n4148 is too weak ?
Adding the 10ohm to the existing layout is very easy, i had planned it when i made the pcb.
Yes, the acsweep shows some artefacts at 30mhz, this seems the frequency where feedback collapses.
I once gave up having a perfect looking ac-sweep and concentrated on optimizing squarewaveresponse to have
low internal overshooting and no ringing. I had scope attached while playing music and never observed any
stabilityproblem. But there could be optimisation possible. I made the experience that stability is the
most important thing when using nfb, any instability (not just oscillating or not) causes bad/strange sound.
But, obviously i do not like millercaps...
Maybe you can detect with your experience some last problems ?
The 100pf in the 2nd stage seems quite uncritical as it is not a real millercap, i choosed this value as it
seemed maximum before phasemismatch started to occur in pushpull-operation of the vas. I used this one
to replace the RC in LTP i used before, but it showed internal overshooting.
I personally think, this little amplifier shows how much is possible with standard-topology...
Mike
Phew, many responses !
First, big thanks to Sheldon for the evaluation, makes me proud that symasym can at least keep up
with your tubeamps ! Also for me, the power is way enough for serious listening or to bug neighbors !
And i am very reliefed that you are pleased with it !
Yes, simple circuit without too exotic parts was one of my priority goals, and having no turn on/off thump
is simply a must for me. I do not like having to add protectionrelays afterwards...
Uncolorized/natural sound was also top priority !
I am quite sure that the amp is stable, the scope shows 2mv RF-stuff, but no matter if it is turned on or off...
If there would be an instability, it should have shown up with the squarewavetest.
And, very nice job with the cases ! And yes, symasym loves percussions !
Anatech, why not trying, it is not too expensive and you might have most parts already...
I have no site or webpage yet, all plans/instructions/datas are spread over the whole thread, maybe i should
collect them all and make up a nice html ?
Which japanese transistors do you want to try ? sc2240/sa970 ?
I am not sure what happens if the 2n5551/5401 are substituted by devices with more gain, no idea...
PMA, the boardfiles on page 22 are the latest, the boards i use are a direct predecessor, until then i only
made minor changes, nothing that would be critical if my brain is still functional...
The traces on the upper layer are some "misuse" by me to easily implement wirejumpers.
This should only be a problem when giving these files into industrial production.
I have not etched the very latest version, but it is extremely unlikely that they have an error.
Thanks for the tip with the 10ohms, it would be really bad if they burn up, do you think a 1n4148 is too weak ?
Adding the 10ohm to the existing layout is very easy, i had planned it when i made the pcb.
Yes, the acsweep shows some artefacts at 30mhz, this seems the frequency where feedback collapses.
I once gave up having a perfect looking ac-sweep and concentrated on optimizing squarewaveresponse to have
low internal overshooting and no ringing. I had scope attached while playing music and never observed any
stabilityproblem. But there could be optimisation possible. I made the experience that stability is the
most important thing when using nfb, any instability (not just oscillating or not) causes bad/strange sound.
But, obviously i do not like millercaps...
Maybe you can detect with your experience some last problems ?
The 100pf in the 2nd stage seems quite uncritical as it is not a real millercap, i choosed this value as it
seemed maximum before phasemismatch started to occur in pushpull-operation of the vas. I used this one
to replace the RC in LTP i used before, but it showed internal overshooting.
I personally think, this little amplifier shows how much is possible with standard-topology...
Mike