Hi Mike,
Just got a "sample kit" from On Semi. It has two pairs of MJW0281A and MJW0302A. I'll see how close they are to the previous samples. I am really looking forward to these little guys. You did try them, didn't you Mike? Here is the data sheet in PDF
Also, with any luck I'll be getting some IT120A's from Linear Systems, as well as LS841 and LSK389. Guess what they are for?
The only other thing are caps. I did find some 3U3 uF units and have ordered the silly things. 5mm 4u7 is scarce here. Can't find any. I did order 40 1u0. Should I parallel a ton of them?
Newark seems to have some selection. I can post their stock numbers if anyone would like.
-Chris
Just got a "sample kit" from On Semi. It has two pairs of MJW0281A and MJW0302A. I'll see how close they are to the previous samples. I am really looking forward to these little guys. You did try them, didn't you Mike? Here is the data sheet in PDF
Also, with any luck I'll be getting some IT120A's from Linear Systems, as well as LS841 and LSK389. Guess what they are for?
The only other thing are caps. I did find some 3U3 uF units and have ordered the silly things. 5mm 4u7 is scarce here. Can't find any. I did order 40 1u0. Should I parallel a ton of them?
Newark seems to have some selection. I can post their stock numbers if anyone would like.-Chris
Hi Chris, i still could send you some of these Wima 4.7uf 5mm... These are obviously only easy to get in europe.
I tried the MJL0281/0302, but i am sure they are identical to the MJWs except the case.
Does this sample kit also contain MJE15030/31 ?
Hmmm, nice jfet inputs ? I have some sk170/sj74 and sk389 left... 😀
Mike
I tried the MJL0281/0302, but i am sure they are identical to the MJWs except the case.
Does this sample kit also contain MJE15030/31 ?
Hmmm, nice jfet inputs ? I have some sk170/sj74 and sk389 left... 😀
Mike
Hi Mike,
I might try a couple 4u7 type then if you don't mind. I can paypal you.
The kit only includes the spec sheet and two of each transistor type. No drivers of any kind (you would think they would include them in case someone uses old junk types!). The Japanese types are getting hard to get over here.
The Jfet types should be interesting. They come in a 6 leg TO-71 metal case. This makes things easier than the original 2SK389 to mount. I used to like the old uPA68H. The NPN diff pair I ordered also comes in the TO-71 case.
Linear Systems can be found here. I didn't get a confirmation, but rather an email saying a rep would contact me. Let's hope I can get some pieces and figure out just how well they will work. They may be great, or not. They do look promising and if supply is stable .........
-Chris
I might try a couple 4u7 type then if you don't mind. I can paypal you.
The kit only includes the spec sheet and two of each transistor type. No drivers of any kind (you would think they would include them in case someone uses old junk types!). The Japanese types are getting hard to get over here.
The Jfet types should be interesting. They come in a 6 leg TO-71 metal case. This makes things easier than the original 2SK389 to mount. I used to like the old uPA68H. The NPN diff pair I ordered also comes in the TO-71 case.
Linear Systems can be found here. I didn't get a confirmation, but rather an email saying a rep would contact me. Let's hope I can get some pieces and figure out just how well they will work. They may be great, or not. They do look promising and if supply is stable .........
-Chris
PayPal works great, we can handle the rest via email, but now, it's time for me to search my bed...
Mike
Mike
Hi Mike,
It sure looks like it's the same die. Soa and all other curves look the same. They are guaranteeing the gain match to 5A for the MJW and 3A for the MJL types. Interesting, must be a typo.
-Chris
Edit: 'night Mike, works for me.
It sure looks like it's the same die. Soa and all other curves look the same. They are guaranteeing the gain match to 5A for the MJW and 3A for the MJL types. Interesting, must be a typo.
-Chris
Edit: 'night Mike, works for me.
my progress
Hi Michael!
Please look at my efforts,
I do not have enough time to finish your amp v. 5.3.
As you can see I paralleled 5 pcs of 1 ohm thick film resistors instead of 0,22 ohm emitter resistor, to minimalise its inductance.
As VAS transistors I used the pairs of BD243C/244C, what do you think, will they work properly?
The Sankens have too large cases, so I had to solder them at a certain angle to be able to mount them on a heatsink.
For soldering I used Pb-Ag alloy (4%Ag).
I have some circumstances regarding Zobel network and output-choke inductance, if they should be soldered on the board?
Many sources say, that Zobel should be mounted far away from the input of the amp, on speakers terminals, the same like the choke… do you think is it worth to try?
Hi Michael!
Please look at my efforts,
I do not have enough time to finish your amp v. 5.3.
As you can see I paralleled 5 pcs of 1 ohm thick film resistors instead of 0,22 ohm emitter resistor, to minimalise its inductance.
As VAS transistors I used the pairs of BD243C/244C, what do you think, will they work properly?
The Sankens have too large cases, so I had to solder them at a certain angle to be able to mount them on a heatsink.
For soldering I used Pb-Ag alloy (4%Ag).
I have some circumstances regarding Zobel network and output-choke inductance, if they should be soldered on the board?
Many sources say, that Zobel should be mounted far away from the input of the amp, on speakers terminals, the same like the choke… do you think is it worth to try?
Attachments
Hi padamiecki, about the sankens... 😀 Everything somehow fits !
About BD243 as vas transistors, thats a big no no, it has 12 times the capacitance and 50 times lower ft than the 2n5401, that's even bad as driver. You really should keep the 2n5401/5551 here, they are not really subject to substitution. Also, it is a to220 with different pinout than 2n5401, will be difficult to fit onto the pcb.
Or did you mean using them as drivers instead of MJE15030/31 ?
Yes, it should not be bad to move the outputcoil from the pcb, but you should keep the RC (4.7R + 47nf) where it is. Don't forget to replace the 10ohms with a bridge on the pcb.
I heard that the RC needs to be as close as possible to the outputdevices...
Mike
About BD243 as vas transistors, thats a big no no, it has 12 times the capacitance and 50 times lower ft than the 2n5401, that's even bad as driver. You really should keep the 2n5401/5551 here, they are not really subject to substitution. Also, it is a to220 with different pinout than 2n5401, will be difficult to fit onto the pcb.
Or did you mean using them as drivers instead of MJE15030/31 ?
Yes, it should not be bad to move the outputcoil from the pcb, but you should keep the RC (4.7R + 47nf) where it is. Don't forget to replace the 10ohms with a bridge on the pcb.
I heard that the RC needs to be as close as possible to the outputdevices...
Mike
MikeB said:
😀 just use more heavy hammer
MikeB said:
yes, I meaned those devices! I made a mistake called them VAS transistors
MikeB said:
I missed somehow an information about bridging 10ohms res, thank you for it!
MikeB said:I heard that the RC needs to be as close as possible to the outputdevices...
output devices = speakers?
maybe PMA would advice?
padamiecki said:
But, still as drivers these are lousy, with ft=3mhz they are 10 times slower than MJE15030 or your Sankens.
The coil was in paralell to the 10ohm, if you skip the coil you need to short the 10ohm...
Mike
Hi Mike,
The coil is important to isolate the feedback network from the outside world. Don't you think there may be a problem possibly?
-Chris
The coil is important to isolate the feedback network from the outside world. Don't you think there may be a problem possibly?
-Chris
MikeB said:
I thought that you proposed to link R2, now I understand.More, I can see that MJE15030 are necessary...
How about Zobel? Better leave it on the board?
anatech said:
It shouldn't, Pavel (PMA) operates his symasym without any coil. But haven't tried...
padamiecki said:
More, I can see that MJE15030 are necessary...
How about Zobel? Better leave it on the board?
I think, keep the zobel as it is, it's asking for problems moving it. (in theory)
For the beginning you might build it as suggested ?
Mike
In the reality, respecting the voltage limits and the lower impedance limit.
Symassym behaves as Bullet proof amplifier...something hardly reliable.
It could silent some Katiuscha boys that we have in our forum...the unit is so good that those bombardier Raiders did not entered to smash Symassym.... this one they had to eat without Ketchup...aahahahahhaha!
The unit was aproved by Epupa!!!... and this man, as you all know, or at least have already perceived, has enormous high standards of quality inside his mind...he do not turn happy with normal, commom, standard, average amplifiers...the best is the minimum possible to him... and i think he wants even more than that.
The amplifier is something shielded against criticisms...and surrounding it there are a lot of good guys to defend...also enormous quantity of support friends that had constructed this nice unit.
Much better than that, was proved, without any doubt, that a dedicated, hardly worker computer programmer can do a nice design job too.
Observe the number of hits, the number of people that already construct this unit.... how many countries have their foruns filled with pictures, texts and linkis to Symassym thread.
The unit was developed since the first stage by Michael Bittner...i am one of the testimonies of that, also Mr. John Mateus from USA... we go following his progress, watching his dedication to make simple, unexpensive to produce, with the best possible quality with easy to find components, and comparing it with good amplifiers and listening other guys evaluations too....... listening with open ears...not listening because of education, that behavior people listen and turn the backs for the one that suggest...he listened, be had beliefs that people may could perceive something strange, he made efforts to perceive too and he repaired the ancient designs that turns into this one.
This is not a revisiting, not a X amplifier re-edition, not an Y amplifier upgrade and updated.
A very good work, from a very special man that we have to respect...born in this forum and reached the maturity here
A genuine forum design, started inside our forum, developed by someone that bellong to our group.... our designer...made to us!.
Yeah!!!!..sounds very good...do not oscilate and it is Guaranteed!
regards,
Carlos
Symassym behaves as Bullet proof amplifier...something hardly reliable.
It could silent some Katiuscha boys that we have in our forum...the unit is so good that those bombardier Raiders did not entered to smash Symassym.... this one they had to eat without Ketchup...aahahahahhaha!
The unit was aproved by Epupa!!!... and this man, as you all know, or at least have already perceived, has enormous high standards of quality inside his mind...he do not turn happy with normal, commom, standard, average amplifiers...the best is the minimum possible to him... and i think he wants even more than that.
The amplifier is something shielded against criticisms...and surrounding it there are a lot of good guys to defend...also enormous quantity of support friends that had constructed this nice unit.
Much better than that, was proved, without any doubt, that a dedicated, hardly worker computer programmer can do a nice design job too.
Observe the number of hits, the number of people that already construct this unit.... how many countries have their foruns filled with pictures, texts and linkis to Symassym thread.
The unit was developed since the first stage by Michael Bittner...i am one of the testimonies of that, also Mr. John Mateus from USA... we go following his progress, watching his dedication to make simple, unexpensive to produce, with the best possible quality with easy to find components, and comparing it with good amplifiers and listening other guys evaluations too....... listening with open ears...not listening because of education, that behavior people listen and turn the backs for the one that suggest...he listened, be had beliefs that people may could perceive something strange, he made efforts to perceive too and he repaired the ancient designs that turns into this one.
This is not a revisiting, not a X amplifier re-edition, not an Y amplifier upgrade and updated.
A very good work, from a very special man that we have to respect...born in this forum and reached the maturity here
A genuine forum design, started inside our forum, developed by someone that bellong to our group.... our designer...made to us!.
Yeah!!!!..sounds very good...do not oscilate and it is Guaranteed!
regards,
Carlos
Symassym
Hi everybody
It has been a while since last time I said something about this
incredible amplifier but today I think I'll reinforce everybody's
opinion in view of the fact the number of postings on this thread.
I built two versions of this amplifier, the first one upon the original
design and I concluded we were in the presence of a winner as
later on we found out. This amplifier was directed to my son who
needed a PA amplifier for his work. PA amplifier imagine!
But then I felt a little sad to have gotten rid of it even though
the amplifier was given to a very good cause.
So I decided to build another one to complement a series of good
amplifiers I own. And here I want to reveal a little secret to
everybody, a secret that I didn't even reveal to Mike B.
Due to my bad eyesight (I'm getting to be 68) I made the boards
mirrored without even noticeing and after they were ready to
install the components that's when I saw the boards were
reversed. But hallas, I said, I'm not going to make another pair of
boards, I'm going to go ahead and make the amplifier and see
if it works. What a challenge, installing components carefully
trying to respect their positioning the reversed way! Come to
think of it this is not a big deal, except I never faced a situation
like this before.
But guess what? It worked first time...It was just a matter of
adjusting the bias (very easy task) and here it goes playing
music the way it was supposed to.
I'm revealing this just to prove one thing, this is an "explendid"
amplifier that works the right way, upside down, mirrored way,
you name it. And what's incredible is it works, it plays with the
very same quality.....
So, to finish the story, I'm a proud owner of a UNIQUE piece
of Symasym, the "mirrored Symasym", ah,ah,ah....
Hi everybody
It has been a while since last time I said something about this
incredible amplifier but today I think I'll reinforce everybody's
opinion in view of the fact the number of postings on this thread.
I built two versions of this amplifier, the first one upon the original
design and I concluded we were in the presence of a winner as
later on we found out. This amplifier was directed to my son who
needed a PA amplifier for his work. PA amplifier imagine!
But then I felt a little sad to have gotten rid of it even though
the amplifier was given to a very good cause.
So I decided to build another one to complement a series of good
amplifiers I own. And here I want to reveal a little secret to
everybody, a secret that I didn't even reveal to Mike B.
Due to my bad eyesight (I'm getting to be 68) I made the boards
mirrored without even noticeing and after they were ready to
install the components that's when I saw the boards were
reversed. But hallas, I said, I'm not going to make another pair of
boards, I'm going to go ahead and make the amplifier and see
if it works. What a challenge, installing components carefully
trying to respect their positioning the reversed way! Come to
think of it this is not a big deal, except I never faced a situation
like this before.
But guess what? It worked first time...It was just a matter of
adjusting the bias (very easy task) and here it goes playing
music the way it was supposed to.
I'm revealing this just to prove one thing, this is an "explendid"
amplifier that works the right way, upside down, mirrored way,
you name it. And what's incredible is it works, it plays with the
very same quality.....
So, to finish the story, I'm a proud owner of a UNIQUE piece
of Symasym, the "mirrored Symasym", ah,ah,ah....
No, no, no, you got it all wrong. This is an audio forum. You should have said that you deliberately mirrored the PCBs because it sounds better that way. 🙂