With the signal cable (especially gnd) disconnected, there is no way where signal-gnd should get 3ma. This means there must be a fault on the PCB-layout like connecting r12 to signal-gnd instead of power-gnd.
Can you send me pic of PCB ? (michael at synetic dot de)
Mike
Can you send me pic of PCB ? (michael at synetic dot de)
Mike
Below is pic of PCB, not complited version:
http://www.fotosik.pl/pokaz_obrazek/pelny/7ca348d39fc89d0d.html
http://www.fotosik.pl/pokaz_obrazek/pelny/7ca348d39fc89d0d.html
This pcb was missing a connection at r16, but is obviously fixed now. Can't see other error.
Is it possible that you accidently used 10kohm instead of 10ohm for R2 ?
Can you show pic/photo of final pcb ?
Another possibility would be that you have a floating ground, would be a fault in the PSU.
Michael
Is it possible that you accidently used 10kohm instead of 10ohm for R2 ?
Can you show pic/photo of final pcb ?
Another possibility would be that you have a floating ground, would be a fault in the PSU.
Michael
MikeB
I haven,t final pcb becouse final pcb isn,t my project.
Yoy are genius, of course I have mada a mistake with R2 - 10kR. Maybe I was sleepy when I have solder the pcb
Big Thanks !!! (Dziekuje bardzo !!!)
I have one question, you have used the thosibas output devices, did they improve the sound or measurments of symasym ?
I haven,t final pcb becouse final pcb isn,t my project.
Yoy are genius, of course I have mada a mistake with R2 - 10kR. Maybe I was sleepy when I have solder the pcb
Big Thanks !!! (Dziekuje bardzo !!!)
I have one question, you have used the thosibas output devices, did they improve the sound or measurments of symasym ?
Yipee, problems solved ? 🙂
About output devices, they all sound different, but i did not take measurements from different devices...
I tried 4 different output devices:
- MJL3281/1302, from all devices the "harshest" sound
- sc5200/1943, the softest sound
- MJL21196/5, absolutely beautiful/musical, but need high bias and matching
- MJL0281/0302, my favourites, a good combination of the 3 above, crystal clear but not bright.
They all are good devices, it might be a matter of taste... I think the sc5200/sa1943 are really worth the try, but be careful, they can make symasym oscillate. The at least change for them is to reduce c14 to 10pf. I don't know what happens with 2 output pair version. Sadly the emitter resistors are gone, they were a good way to reduce openloop gain and stabilize.
Pavels measurements were done with Toshibas.
Mike
About output devices, they all sound different, but i did not take measurements from different devices...
I tried 4 different output devices:
- MJL3281/1302, from all devices the "harshest" sound
- sc5200/1943, the softest sound
- MJL21196/5, absolutely beautiful/musical, but need high bias and matching
- MJL0281/0302, my favourites, a good combination of the 3 above, crystal clear but not bright.
They all are good devices, it might be a matter of taste... I think the sc5200/sa1943 are really worth the try, but be careful, they can make symasym oscillate. The at least change for them is to reduce c14 to 10pf. I don't know what happens with 2 output pair version. Sadly the emitter resistors are gone, they were a good way to reduce openloop gain and stabilize.
Pavels measurements were done with Toshibas.
Mike
Borys,
be happy you have not blown your speakers. Put antiparallel diodes across the R2 10 ohm resistor.
be happy you have not blown your speakers. Put antiparallel diodes across the R2 10 ohm resistor.
Now report:
-left channel 0,5mV
-right channel 0,8mV
-no thumbs
-with signal or without - totaly silent, even if I put my ear cose to the speakers
-output dev mjl4302/4281, drivers mje15034/35
I must repeat the measurments, it schould improve very much. I have one pair 5,3pcb with one pair output, I'll try 2sc5200/2sa1943 but I'm not sure about the drivers, maybe better for them will be thosibas drivers like 2sc3298/2sa1306 ?
-left channel 0,5mV
-right channel 0,8mV
-no thumbs
-with signal or without - totaly silent, even if I put my ear cose to the speakers
-output dev mjl4302/4281, drivers mje15034/35
I must repeat the measurments, it schould improve very much. I have one pair 5,3pcb with one pair output, I'll try 2sc5200/2sa1943 but I'm not sure about the drivers, maybe better for them will be thosibas drivers like 2sc3298/2sa1306 ?
It explains why you measured those nasties on background.
I was sure you had wrong ground wiring, in fact high R2 (10k) has made the same problems.
I was sure you had wrong ground wiring, in fact high R2 (10k) has made the same problems.
Hi Borys, yes, that sounds more like symasym... 😀
About the drivers, try it ! At least from padiamecki we know that slow drivers are bad... I guess, fast drivers reduce openloop phasehift which is only beneficial.
Pavel, i was irritated by the offset at r2 without anything connected, this gave 2 options, something feeding 3ma into r2, or r2 beeing too big, causing the offset.
The last option would have been very bad: Oscillation... This makes everything possible.
Mike
About the drivers, try it ! At least from padiamecki we know that slow drivers are bad... I guess, fast drivers reduce openloop phasehift which is only beneficial.
Pavel, i was irritated by the offset at r2 without anything connected, this gave 2 options, something feeding 3ma into r2, or r2 beeing too big, causing the offset.
The last option would have been very bad: Oscillation... This makes everything possible.
Mike
Hello
It´s been a long time for me to do some electronics, but now I am planning to make my third Symasym since I´ve been developing new speaker system that will require another pair of amplifiers.
I will make the 5.3 version with very good quality components but I have a hard time to find MJL0281/0302 devices.
Does anyone know where to get those transistors in Europe (or basically anywhere)?
Jarno
It´s been a long time for me to do some electronics, but now I am planning to make my third Symasym since I´ve been developing new speaker system that will require another pair of amplifiers.
I will make the 5.3 version with very good quality components but I have a hard time to find MJL0281/0302 devices.
Does anyone know where to get those transistors in Europe (or basically anywhere)?
Jarno
Hi Jarno, welcome back !
Sadly, the MJL version seems to be still not on the market, but the MJW version is on stock at www.digikey.com. (>2000) I have no idea where to get it in Europe. But, if you order at digikey items that are on stock, you will have your order ~3 days later. Digikey also has the onsemi mpsa18 and 2n5401/5551. (all on stock)
The MJW is the TO247 version, it has 150watts instead of the 180watts. If you don't push it extremely hard into 4 ohms it should be ok.
You could also use the Toshibas SC5200/SA1943, but i'd still recommend digikey, they are reliable and you get original O-grade.
Mike
Sadly, the MJL version seems to be still not on the market, but the MJW version is on stock at www.digikey.com. (>2000) I have no idea where to get it in Europe. But, if you order at digikey items that are on stock, you will have your order ~3 days later. Digikey also has the onsemi mpsa18 and 2n5401/5551. (all on stock)
The MJW is the TO247 version, it has 150watts instead of the 180watts. If you don't push it extremely hard into 4 ohms it should be ok.
You could also use the Toshibas SC5200/SA1943, but i'd still recommend digikey, they are reliable and you get original O-grade.
Mike
HI
I would like to know if someone has some spare MJL0281A transistor , I have 5pc MJL0302A what I orderd from ON semi .
Sadly the MJL0281A no longer availeble not even at ON semi.
I just call them yestarday because I orderd both in May and I only receved the 0302A , the answer they no longer produce for some reason.
I just try to find some sourse for(even) 2 pc so finaly I can finnish the Symasym .
I willing to trade if some one has a need for the 0302A ....
Thanks for all of you ..
Regards
I would like to know if someone has some spare MJL0281A transistor , I have 5pc MJL0302A what I orderd from ON semi .
Sadly the MJL0281A no longer availeble not even at ON semi.
I just call them yestarday because I orderd both in May and I only receved the 0302A , the answer they no longer produce for some reason.
I just try to find some sourse for(even) 2 pc so finaly I can finnish the Symasym .
I willing to trade if some one has a need for the 0302A ....
Thanks for all of you ..
Regards
Borys, the FJL4315/4215 looks very good, but with its output capacitance of only 200pf it is very fast and symasym might need adjustment...
Gaborbela, that is sad that onsemi does not produce these devices, maybe they had no orders yet ? I don't think they start production for samples only...
You might mix them with the MJW version, they are electrically identical.
I only have few pairs left...
Mike
Gaborbela, that is sad that onsemi does not produce these devices, maybe they had no orders yet ? I don't think they start production for samples only...
You might mix them with the MJW version, they are electrically identical.
I only have few pairs left...
Mike
Hi Gaborbela,
I feel your pain. I didn't order enough of them and I too am fighting to get some more. They were an unexpected surprise to me.
Most people only look at voltage, current and power. On the spec sheet, they look like they are underpowered MJL types. I ordered a couple for testing just being curious, but was blown away by how good the hFE matches were.
I feel On Semi has a real winner with that part, if they would only continue manufacture. It's almost like they were hand selected die, same as their bigger brothers but with tight parameters. What On Semi did not do, was bring attention to these things.
Could be corporate accounting again.
-Chris
I feel your pain. I didn't order enough of them and I too am fighting to get some more. They were an unexpected surprise to me.
Most people only look at voltage, current and power. On the spec sheet, they look like they are underpowered MJL types. I ordered a couple for testing just being curious, but was blown away by how good the hFE matches were.
I feel On Semi has a real winner with that part, if they would only continue manufacture. It's almost like they were hand selected die, same as their bigger brothers but with tight parameters. What On Semi did not do, was bring attention to these things.
Could be corporate accounting again.
-Chris
We should start a petition, "Bring us MJL0302/0281 !!!" ? 😀
Okay, typically they produce thousands, not a few dozens for DIYers. 🙁
At least, digikey has > 2000 of the MJWs in stock.
Mike
EDIT: Maybe if enough people enter a request for MJL0302A/0281A on this link: ?
http://dkc1.digikey.com/scripts/us/commcenter.cgi?action=newproduct
Okay, typically they produce thousands, not a few dozens for DIYers. 🙁
At least, digikey has > 2000 of the MJWs in stock.
Mike
EDIT: Maybe if enough people enter a request for MJL0302A/0281A on this link: ?
http://dkc1.digikey.com/scripts/us/commcenter.cgi?action=newproduct
At $3.29 CDN for one or 28.66 for 10, either type. Not a bad deal really. They have about 2,800 pairs of these on hand at the moment.
Better than getting stuck with fakes eh? Now if On Semi could only come up with a driver transistor to match. How about some cool diff pairs, fets even?
-Chris
Better than getting stuck with fakes eh? Now if On Semi could only come up with a driver transistor to match. How about some cool diff pairs, fets even?
-Chris
anatech said:
Yes, the price for these 0281s are okay... I made some calculations, with adequate heatsink (at least 0.9K/w per channel) these are ok with 36v into 4ohms.
Cool diff pairs ? I think their mpsa18 is already hard to beat... (except the 45v rating)
Their jfets and mosfets are not very interesting, but the mje1503x is not too bad, ft of 70 at 100ma. Inputcapacitance below 1nF, outputcapacitance below 100pF. But MJEs with the matching of the 0281/0302 would be nice...
BTW, Chris, did you measure some of the mje15030/31 ?
Mike
My last measurment (My sound card has to many noise I think):
An externally hosted image should be here but it was not working when we last tested it.
