These transistors 2SC4793 and complementary are great
Maybe in the past i have pointed MJE15030 or any transistor from this series MJE15XXX as being good to be used with 35 volts supplies....but this was my mistake...an error....if is said i was wrong....further testings show me this transistor works better with higher voltages... starting to be good with 63 volts and tollerable at 55 volts....for sure no good at 35 volts supplies.
Observe datasheet and you gonna see it was made for higher voltage operation.
These last days i have confirmed because the lack of BD139/BD140 (wonderfull transistors to be used with 35 volts) these MJEXXXX are no good for sonics..they operate out from the linearity...you perceive this in the sound reproduction..... yes...it plays....some guys may even not perceive..but majority of guys replacing from BD139 and BD140 by MJE15030/MJE15031 will perceive immediately.
I could not see the reason why people get confused referenced by a post made in the past..... we evolute guys...we learn...if i said that..then erase and listen, if you want, what i am saying today...because i realised this today... after a long time...because comparison... when you replace then you compare...you have recent sound memory to compare.
I am saying MJE15030/MJE15031 pair .... also MJE15028/MJE15029 pair..... also MJE15032/MJE15033 pair ..... also MJE15034/MJE15035 pair are no good to operate while using 35 volts supplies...they play sound... but not that good as they can play while powered with higher voltage
I am just informing folks what i have perceived these last days..... what i have learned these last days.
regards,
Carlos
Maybe in the past i have pointed MJE15030 or any transistor from this series MJE15XXX as being good to be used with 35 volts supplies....but this was my mistake...an error....if is said i was wrong....further testings show me this transistor works better with higher voltages... starting to be good with 63 volts and tollerable at 55 volts....for sure no good at 35 volts supplies.
Observe datasheet and you gonna see it was made for higher voltage operation.
These last days i have confirmed because the lack of BD139/BD140 (wonderfull transistors to be used with 35 volts) these MJEXXXX are no good for sonics..they operate out from the linearity...you perceive this in the sound reproduction..... yes...it plays....some guys may even not perceive..but majority of guys replacing from BD139 and BD140 by MJE15030/MJE15031 will perceive immediately.
I could not see the reason why people get confused referenced by a post made in the past..... we evolute guys...we learn...if i said that..then erase and listen, if you want, what i am saying today...because i realised this today... after a long time...because comparison... when you replace then you compare...you have recent sound memory to compare.
I am saying MJE15030/MJE15031 pair .... also MJE15028/MJE15029 pair..... also MJE15032/MJE15033 pair ..... also MJE15034/MJE15035 pair are no good to operate while using 35 volts supplies...they play sound... but not that good as they can play while powered with higher voltage
I am just informing folks what i have perceived these last days..... what i have learned these last days.
regards,
Carlos
Last edited:
Observe something interesting....
BD139 can operate at maximum of 80 volts.... half of that is 40 volts (aprox. 35 volts)
MJE15028 is a 120V transistor .... half of that is 60 volts
MJE15030 is a 150V transistor .... half of that is 75 volts
MJE15032 is a 250V transistor .... half of that is 125 volts
MJE15034 is a 350V transistor .... half of that is 175 volts
And i found that MJE15030 operates fine with 64 volts...say... sounds fine..this make sense.
In the past, down the sixties, manufacturers used to publish a much more detailed specifications and you could see the perfect voltage to operate the transistor, it was usually nearby half of maximum VCEO....now a days they do not do that anymore....maybe the expect us to realise this.
Any transistor that can face your supply voltage, respecting NPN or PNP polarity, respecting the current you gonna operate, respecting the power you will operate and some basic specifications, will work, will sound...there are zilions of possible replacement to each transistor you think and imagine.... but some of them works better, these may be the ones people say "sounds better"..when transistors does not sound better or worse.... what may happen is linearity...operational conditions where the semiconductor does the job better related Linearity.
Unbeatable to 35 volts are BD139/BD140....just unbeatable.... i have never replaced a set of these transistors by others that resulted better...and i did it hundreds of times...usually these transistors finishes in my stock and my supplier (gifts from Joseph Siejack) never has these ones to supply me.... then, because not having them anymore (this is ciclic...repeat from time to time) i am forced to use others... without any advantage...even these 2SC and 2SA Hugh uses are not better...they are just not bad...they are also high voltage units that performs better while operating with higher voltages (55V or more....better to use 64 Volts with them)...reason why i have pointed these ones as replacement into my amplifiers that operates with higher voltages in the supply.
These 2SC and 2SA lovely plastic models Hugh uses are good..they have the correct gain we need, they do not need insulators because plastic, they can operate with higher voltage...and they are better than BD139/BD140 when you have high voltage applications...because under these voltages these BD139/140 pops out, burns, explode, melt, goes shorted!...they just cannot face these voltages..... this is what make them not good for higher voltages.
regards,
Carlos
BD139 can operate at maximum of 80 volts.... half of that is 40 volts (aprox. 35 volts)
MJE15028 is a 120V transistor .... half of that is 60 volts
MJE15030 is a 150V transistor .... half of that is 75 volts
MJE15032 is a 250V transistor .... half of that is 125 volts
MJE15034 is a 350V transistor .... half of that is 175 volts
And i found that MJE15030 operates fine with 64 volts...say... sounds fine..this make sense.
In the past, down the sixties, manufacturers used to publish a much more detailed specifications and you could see the perfect voltage to operate the transistor, it was usually nearby half of maximum VCEO....now a days they do not do that anymore....maybe the expect us to realise this.
Any transistor that can face your supply voltage, respecting NPN or PNP polarity, respecting the current you gonna operate, respecting the power you will operate and some basic specifications, will work, will sound...there are zilions of possible replacement to each transistor you think and imagine.... but some of them works better, these may be the ones people say "sounds better"..when transistors does not sound better or worse.... what may happen is linearity...operational conditions where the semiconductor does the job better related Linearity.
Unbeatable to 35 volts are BD139/BD140....just unbeatable.... i have never replaced a set of these transistors by others that resulted better...and i did it hundreds of times...usually these transistors finishes in my stock and my supplier (gifts from Joseph Siejack) never has these ones to supply me.... then, because not having them anymore (this is ciclic...repeat from time to time) i am forced to use others... without any advantage...even these 2SC and 2SA Hugh uses are not better...they are just not bad...they are also high voltage units that performs better while operating with higher voltages (55V or more....better to use 64 Volts with them)...reason why i have pointed these ones as replacement into my amplifiers that operates with higher voltages in the supply.
These 2SC and 2SA lovely plastic models Hugh uses are good..they have the correct gain we need, they do not need insulators because plastic, they can operate with higher voltage...and they are better than BD139/BD140 when you have high voltage applications...because under these voltages these BD139/140 pops out, burns, explode, melt, goes shorted!...they just cannot face these voltages..... this is what make them not good for higher voltages.
regards,
Carlos
Last edited:
I think you will find that the ONsemi drivers need much more current to get them into a "good" operating range. I don't think it is a lack of Vce that is causing any problems.
Similarly it is current that gets the bd139/140 into their "good" range of operation. These much smaller devices do not need as much current as the big ONsemi devices.
Similarly it is current that gets the bd139/140 into their "good" range of operation. These much smaller devices do not need as much current as the big ONsemi devices.
D
Deleted member 148505
D
Deleted member 148505
Hi
For those who had built this amp, what value is better for the bootstrap cap 220uf or 100uf?
Thanks
For those who had built this amp, what value is better for the bootstrap cap 220uf or 100uf?
Thanks
Jlester,
You have made an exceptionally good layout, nice track width and profiling, very neat!
Can I ask how you will connect the Vbe multiplier? That component is always tricky!!
Hats off!
C6 is phase lead. It means you achieve slightly better stability with a reduced value of lag compensation (so called Miller compensation cap) and it seems to control sibilance rather better with the sung or spoken consonant 's'.
BTW, bootstrap cap need not exceed 100uF. Higher makes no difference to the bass at all.
Cheers,
Hugh
You have made an exceptionally good layout, nice track width and profiling, very neat!
Can I ask how you will connect the Vbe multiplier? That component is always tricky!!
Hats off!
C6 is phase lead. It means you achieve slightly better stability with a reduced value of lag compensation (so called Miller compensation cap) and it seems to control sibilance rather better with the sung or spoken consonant 's'.
BTW, bootstrap cap need not exceed 100uF. Higher makes no difference to the bass at all.
Cheers,
Hugh
Last edited:
Hi Hugh ,
In the conceptual schematic, c6 is connected between the base of T2 and collector of vbe multiplier T4. But I noticed that on post#507, your suggestion was to connect it between the base of T2 and the collector of Q3(which is also the emitter of T4).
Which one is better, and kindly comment on the difference in effect the two positions have on the overall sound. Thanks.
On jlester's PCB I think the vbe is mounted just like Greg's (and I think the commercial AKSA)
In the conceptual schematic, c6 is connected between the base of T2 and collector of vbe multiplier T4. But I noticed that on post#507, your suggestion was to connect it between the base of T2 and the collector of Q3(which is also the emitter of T4).
Which one is better, and kindly comment on the difference in effect the two positions have on the overall sound. Thanks.
On jlester's PCB I think the vbe is mounted just like Greg's (and I think the commercial AKSA)
Hi can you give me pcb layout and dateil parts list with speaker protection circuit bacause i think ther is no speaker protection on circuit
This amplifier does not have protection for the speaker, nor for the amplifier built in.
Look elsewhere if that is what you need.
Look elsewhere if that is what you need.
If you read the early pages of the thread and check the original AKSA 55 on which this is based, you can see there never has been any speaker protection and for specific performance reasons. Unless Greg has the time to prepare them, there is no BOM but a PDF of the PCBs is attached to #35
Of course, you are free to adapt this pattern with relays or anything if you wish.
hi sanbadgujar,
You will find more details here:
B-AKSA 55
Note: Off-board zobel and speaker protection.
You've been so quiet ultimately.
This is a vídeo from an audio meeting.
https://www.youtube.com/watch?v=0Qu8oXqmFYk
This is a vídeo from an audio meeting.
https://www.youtube.com/watch?v=0Qu8oXqmFYk
Hi farjon,
Can you let us know a few details. I can't make much out from the video.
regards
Well, the audio track has been muted. Copyrights...
A friend of mine opened an audio room where we can meet, exchange ideas and listen music and equipments.
I'm the black t-shirt guy. In this video my Baby-Aksa (the board at center) was playing through DIY loudspeakers that we called here "The Baubos".
These loudspeakers and the mini books was my friend's DIY creations.
There is also a DIY valve preamp at right. Others are Brystol power amplifier, a Atom PC enclosed in wood and a sort of DACs.
Other videos can be found here: https://www.youtube.com/watch?v=wNE9YYJNF-w&list=PLJXPE81Kbc8zAKTXqY8FGAQwHTy2-Nl4X
Rgds.
A friend of mine opened an audio room where we can meet, exchange ideas and listen music and equipments.
I'm the black t-shirt guy. In this video my Baby-Aksa (the board at center) was playing through DIY loudspeakers that we called here "The Baubos".
These loudspeakers and the mini books was my friend's DIY creations.
There is also a DIY valve preamp at right. Others are Brystol power amplifier, a Atom PC enclosed in wood and a sort of DACs.
Other videos can be found here: https://www.youtube.com/watch?v=wNE9YYJNF-w&list=PLJXPE81Kbc8zAKTXqY8FGAQwHTy2-Nl4X
Rgds.
Hi farjon,
Any chance you could post some close up pictures of the amp.
Was the amp well received?
regards
Any chance you could post some close up pictures of the amp.
Was the amp well received?
regards