Thanks Mike,
I'll try with 22p NPO caps. For the 499 Ohm, I'll try two 1K in parallel.
Still can't see why changing to 18K/27p should have such serious consequences, given that it results in just about identical knee frequency, but I'll trust you on that one. Seems that designing amplifiers is as much art as it is science.
Regards,
Hans.
I'll try with 22p NPO caps. For the 499 Ohm, I'll try two 1K in parallel.
Still can't see why changing to 18K/27p should have such serious consequences, given that it results in just about identical knee frequency, but I'll trust you on that one. Seems that designing amplifiers is as much art as it is science.
Regards,
Hans.
Hi Hans !
Using 2 1k in paralell does the job...
About the 22p, if changing this cap i would recommend to reduce it,
and not to increase it. My experience is that having this cap too big
easily results in oscillation.
The problem about changing the feedbacknetwork is, that the ratio
of closedloop-gain to openloop-gain changes and therefore change
the nature of the whole feedback. Your suggested change is not
big and should be harmless, but such a minimal change in gain
would not be really audible and so i suggest to keep it original.
(It's just that i can't guarantee that there are no sideeffects)
Mike
Using 2 1k in paralell does the job...
About the 22p, if changing this cap i would recommend to reduce it,
and not to increase it. My experience is that having this cap too big
easily results in oscillation.
The problem about changing the feedbacknetwork is, that the ratio
of closedloop-gain to openloop-gain changes and therefore change
the nature of the whole feedback. Your suggested change is not
big and should be harmless, but such a minimal change in gain
would not be really audible and so i suggest to keep it original.
(It's just that i can't guarantee that there are no sideeffects)
Mike
Someone asked something about Star earth
Or Star Ground if you mind with those terms.
To the ones that need some explanation about this subject, please take a look at this link, as the explanation is good to understanding.
http://www.diyaudio.com/forums/showthread.php?postid=696439#post696439
regards,
Carlos
Or Star Ground if you mind with those terms.
To the ones that need some explanation about this subject, please take a look at this link, as the explanation is good to understanding.
http://www.diyaudio.com/forums/showthread.php?postid=696439#post696439
regards,
Carlos
Atention!,Achtung!, Atenção!, Atencion!...there are problems with BC639 pins
You can find different pins, related Base position and emitter position.
I already had problems with this transistor because of that.
This way, i am showing you one example...between Philips or Fairchild and Siemens.
Check with your diode test, the one you have in your multimeter...for the ones that do not know, the base is the only pin that you can have conduction to the others two pins fixing one probe point on it.... inverting cannot conduct to other pins.
See the pins inverted.
regards,
Carlos
You can find different pins, related Base position and emitter position.
I already had problems with this transistor because of that.
This way, i am showing you one example...between Philips or Fairchild and Siemens.
Check with your diode test, the one you have in your multimeter...for the ones that do not know, the base is the only pin that you can have conduction to the others two pins fixing one probe point on it.... inverting cannot conduct to other pins.
See the pins inverted.
regards,
Carlos
Attachments
Here is the oposite sittuation, this is dangerous.
So, as those forum people use to say, always test your amplifiers using series resistors from the supply into the amplifiers rails.
Good practice is to use a fuse to speaker.
See pins inverted related other manufacturers.
regards,
Carlos
So, as those forum people use to say, always test your amplifiers using series resistors from the supply into the amplifiers rails.
Good practice is to use a fuse to speaker.
See pins inverted related other manufacturers.
regards,
Carlos
Attachments
This transistor is not the recomended transistor for Symassym4 or even Symassym5 amp.
Michael do not like them, as he prefer more modern and lower capacitance units.
But despite of that, they work in the VAS position without problems, and have a very nice FT and reasonable Hfe.
Of course, using the ones Michael suggest, you will have the guarantee that all data he informed be correct in real world.
I am using them, because I have not the correct ones.
Attached some informs from data sheet.... i could see units that can work with 100 volts.... and i have tested that, connecting one unit to a 100 Volts supply.
This transistor problem is the gain, around 150.
regards,
Carlos
Michael do not like them, as he prefer more modern and lower capacitance units.
But despite of that, they work in the VAS position without problems, and have a very nice FT and reasonable Hfe.
Of course, using the ones Michael suggest, you will have the guarantee that all data he informed be correct in real world.
I am using them, because I have not the correct ones.
Attached some informs from data sheet.... i could see units that can work with 100 volts.... and i have tested that, connecting one unit to a 100 Volts supply.
This transistor problem is the gain, around 150.
regards,
Carlos
Attachments
Hi Carlos !
The bc639/640 is no problem, it's quite similar to the 2n5551/2n5401,
gain is nearly identical with 150. The 2n5401 is slightly faster and
more modern (whatever it does mean) and has much higher voltage-
rating. So, the bc639 is a good substitute !
Mike
The bc639/640 is no problem, it's quite similar to the 2n5551/2n5401,
gain is nearly identical with 150. The 2n5401 is slightly faster and
more modern (whatever it does mean) and has much higher voltage-
rating. So, the bc639 is a good substitute !
Mike
Hi Carlos,
If this thread wasn't started by you , then i think it must not be an interesting one because you are excellent at presenting the Mike's great amp to all of us...
Thanx once again..
K a n w a r
If this thread wasn't started by you , then i think it must not be an interesting one because you are excellent at presenting the Mike's great amp to all of us...
Thanx once again..
K a n w a r
Well kanwar, what can i say...hummm, very happy i am with that.
As i think i could cooperate with Mike, and the "chucrute" is an old friend.
And as i like the amplifier sound, it is not difficult to suggest it to our forum guys, and i can do it without fear that they can be deceptive and call me Charlotte.
This is very difficult to happen, the amplifier sounds very nice.
You like me Kanwar, the same way i apreciate you and more India people, alike Palesha and others...this makes you see me with more kind eyes, if you analise with some care.
First- I talk too much...very noisy i am.
Second - My English is awfull
Third- I do not feel shame to express clearly my ideas...this is not completelly educated.
The eyes from your heart cannot see that
Thanks,
Carlos
As i think i could cooperate with Mike, and the "chucrute" is an old friend.
And as i like the amplifier sound, it is not difficult to suggest it to our forum guys, and i can do it without fear that they can be deceptive and call me Charlotte.
This is very difficult to happen, the amplifier sounds very nice.
You like me Kanwar, the same way i apreciate you and more India people, alike Palesha and others...this makes you see me with more kind eyes, if you analise with some care.
First- I talk too much...very noisy i am.
Second - My English is awfull
Third- I do not feel shame to express clearly my ideas...this is not completelly educated.
The eyes from your heart cannot see that
Thanks,
Carlos
Hi Carlos !
Point 1: No, i don't think so...
Point 2: Who cares ? (not really bad)
Point 3: No problem at all, if you tell BS, you are told...
Mike
Point 1: No, i don't think so...
Point 2: Who cares ? (not really bad)
Point 3: No problem at all, if you tell BS, you are told...
Mike
Mike...harharhar...by the way...this avatar...it seems ....
It is a girl Mike!!!
hehe, image not compatible with you man.
Thank you by the support Mike, very kind...but you had found a female to the avatar.
regards,
Carlos
It is a girl Mike!!!
hehe, image not compatible with you man.
Thank you by the support Mike, very kind...but you had found a female to the avatar.
regards,
Carlos
I installed the Symasym4 as a home theater.
Only one channel to observe the awfull audio quality of cable TV.... really, very noisy, i could heard on my Television Set...and the TV set was considered guilty.
Negative!...the fiber optics receiver produces noises into the audio band...checked with headphones.
But sounded great...i am still hearing.
regards,
Carlos
Only one channel to observe the awfull audio quality of cable TV.... really, very noisy, i could heard on my Television Set...and the TV set was considered guilty.
Negative!...the fiber optics receiver produces noises into the audio band...checked with headphones.
But sounded great...i am still hearing.
regards,
Carlos
Attachments
This amplifier is precious, i personally apreciate the sound.
I will be happy to know if someone had constructed or are in the run to finish, or even has plans to assemble.
Satisfaction is guaranteed!
I think some guys did it, but some of them ashamed to recognize that this unit had kicked many others.... And the oposite, if someone is deceptive with this amplifier, i will be very surprised but will be good to know other guy's ideas about it.
Please, inform me directly if you prefer... i am having healthy and civilized discussions with Mike, telling him to give more detailed support to this thread, as this amplifier is great and i had not enougth good informations about the number of guys constructing...this number is not directly proportional to the amplifier quality, and i am very surprised about that.
nanabrother@yahoo.com
Michael and I, we are very close friends, we have constructed a very solid relationship, that could win some crashes and accidents...so....no problem related us, we have just beeing discussing about the time he spent here.
regards,
Carlos
I will be happy to know if someone had constructed or are in the run to finish, or even has plans to assemble.
Satisfaction is guaranteed!
I think some guys did it, but some of them ashamed to recognize that this unit had kicked many others.... And the oposite, if someone is deceptive with this amplifier, i will be very surprised but will be good to know other guy's ideas about it.
Please, inform me directly if you prefer... i am having healthy and civilized discussions with Mike, telling him to give more detailed support to this thread, as this amplifier is great and i had not enougth good informations about the number of guys constructing...this number is not directly proportional to the amplifier quality, and i am very surprised about that.
nanabrother@yahoo.com
Michael and I, we are very close friends, we have constructed a very solid relationship, that could win some crashes and accidents...so....no problem related us, we have just beeing discussing about the time he spent here.
regards,
Carlos
Re: This amplifier is precious, i personally apreciate the sound.
whose satisfaction are you guaranteeing, Carlos?
does the amp suffer from first cycle distortion? how about NFB? or back-EMF? does it use blackgate cap? or the right snubber? or low-noise precision resistors (you know, the good old carbon film resistors suck)?
destroyer X said:
whose satisfaction are you guaranteeing, Carlos?
does the amp suffer from first cycle distortion? how about NFB? or back-EMF? does it use blackgate cap? or the right snubber? or low-noise precision resistors (you know, the good old carbon film resistors suck)?
Whose satisfaction ? Your ears !
First cycle distortion ? As good as a bandwidthlimited amp can reproduce a non bandwidthlimited signal...
NFB ? 58db
back-EMF ? Don't know, it sounds good... Sims do not show problems with the ariel-model
Blackgatecaps ? In PSU i use BC-caps, on amp is use standard elys...
Snubbers ? Not in the amp... 😉
Resistors ? metal film only of course... What a question ! 😀
My prototype has no audible noise or hum...
Mike
First cycle distortion ? As good as a bandwidthlimited amp can reproduce a non bandwidthlimited signal...
NFB ? 58db
back-EMF ? Don't know, it sounds good... Sims do not show problems with the ariel-model
Blackgatecaps ? In PSU i use BC-caps, on amp is use standard elys...
Snubbers ? Not in the amp... 😉
Resistors ? metal film only of course... What a question ! 😀
My prototype has no audible noise or hum...
Mike