Boys... Todd Johnson offered himself to make another schematic
Including the last modifications made:
Inclusion of a 10 ohms resistance in the second VAS emitter, 10 ohms is fine, sadly have to cut the copper trace to install the resistance in series with the emitter, it can be soldered below the board.
Increase of the first VAS emitter resistance from 100 ohms to 200 ohms.
Removal of that 470pf capacitor, the one was installed from second VAS colector to ground.
Removal of the 18pf feedback capacitor, the one is in the second differential, in the feedback line, in parallel with the 12K resistance.
Reduction of rail resistances.... we had 150 and 220 ohms... now install a resistance from 22 ohms to 39 ohms (27 or 33 can be used naturally)... same value to both rails... we where having too much voltage drop during peaks of consumption..this was producing assymetrical clipping.
The Miller capacitor was increased to 100pf..... was 82pf...you can substitute or solder 18pf, 20 pf, 22pf or 27pf below the board, in parallel with the 82pf already installed.
The current i like to use is 33 miliamperes..because this results in 545 milivolts from base to emitter in the output transistors....measurement prefered by me is 3.3 volts after fuse removal (over 100 ohms rail series protective resistances)...but of course 4.7 is fine too.... and some guys have tried higher value.... 6.9 was used and i knew someone adjusted to 10 volts (100 miliamperes.
Well, this adjustment is very good to be made while listening...very low levels...also you gonna have results in the normal listening.... i think that increasing too much you gonna loose some low level high frequency details...but this is personnal...up to you...enjoy this amplifier.
It is the best wide world amplifier in my opinnion...i have not listened better.
Here you have an image...this one specially offered (the make up, the modifications made and allocated, by Rudi, our German Division)...the 10 ohms is not appearing...well...it is to be installed bellow the board.
I will ask you, please, not to assemble my amplifier if you have spent too much money in other brands...or if you have something you love in your home...made by you or bougth....you gonna hate the ones you have after listen this one...so..better to be living in the illusion the one you have is good..it is not!..compared to this one..guaranteed that the ones you have will loose!
I have a solution..build this one and never compare..never make an A to B comparison..this way you will be rid of troubles, or frustrations...and will let your previous, former, amplifier untouched..you can even make your own mind to believe the former is better (heheheheheheh..do not compare)
This amplifier was conceived by Douglas Self...also there are ideas from Hugh Dean..... divinities from the Audio Skies!.... i gave them a good hand, putting these things together and tunning a little bit...but i think i am not more than a working slave.... the idea came from them..i have worked.
regards,
Carlos
Including the last modifications made:
Inclusion of a 10 ohms resistance in the second VAS emitter, 10 ohms is fine, sadly have to cut the copper trace to install the resistance in series with the emitter, it can be soldered below the board.
Increase of the first VAS emitter resistance from 100 ohms to 200 ohms.
Removal of that 470pf capacitor, the one was installed from second VAS colector to ground.
Removal of the 18pf feedback capacitor, the one is in the second differential, in the feedback line, in parallel with the 12K resistance.
Reduction of rail resistances.... we had 150 and 220 ohms... now install a resistance from 22 ohms to 39 ohms (27 or 33 can be used naturally)... same value to both rails... we where having too much voltage drop during peaks of consumption..this was producing assymetrical clipping.
The Miller capacitor was increased to 100pf..... was 82pf...you can substitute or solder 18pf, 20 pf, 22pf or 27pf below the board, in parallel with the 82pf already installed.
The current i like to use is 33 miliamperes..because this results in 545 milivolts from base to emitter in the output transistors....measurement prefered by me is 3.3 volts after fuse removal (over 100 ohms rail series protective resistances)...but of course 4.7 is fine too.... and some guys have tried higher value.... 6.9 was used and i knew someone adjusted to 10 volts (100 miliamperes.
Well, this adjustment is very good to be made while listening...very low levels...also you gonna have results in the normal listening.... i think that increasing too much you gonna loose some low level high frequency details...but this is personnal...up to you...enjoy this amplifier.
It is the best wide world amplifier in my opinnion...i have not listened better.
Here you have an image...this one specially offered (the make up, the modifications made and allocated, by Rudi, our German Division)...the 10 ohms is not appearing...well...it is to be installed bellow the board.
I will ask you, please, not to assemble my amplifier if you have spent too much money in other brands...or if you have something you love in your home...made by you or bougth....you gonna hate the ones you have after listen this one...so..better to be living in the illusion the one you have is good..it is not!..compared to this one..guaranteed that the ones you have will loose!
I have a solution..build this one and never compare..never make an A to B comparison..this way you will be rid of troubles, or frustrations...and will let your previous, former, amplifier untouched..you can even make your own mind to believe the former is better (heheheheheheh..do not compare)
This amplifier was conceived by Douglas Self...also there are ideas from Hugh Dean..... divinities from the Audio Skies!.... i gave them a good hand, putting these things together and tunning a little bit...but i think i am not more than a working slave.... the idea came from them..i have worked.
regards,
Carlos
Attachments
Updated schematic and component layout. Version 1.5 attached. I'll update the other layouts and the BOM later, when I get a chance, and submit them to Greg (the DX Amp website) after they are all finished.
..Todd
..Todd
Very good Taj....... just great!....... excellent....also good to submit to Greg.
I will open a new thread about the Dx Blame ST soon...this one is big and confused....had many troubles.
regards,
Carlos
I will open a new thread about the Dx Blame ST soon...this one is big and confused....had many troubles.
regards,
Carlos
Nice board Sound..... pretty picture, beautifull construction
thank you very much.
regards,
Carlos
thank you very much.
regards,
Carlos
I will assemble another Dx Blame ST..this one will use BD139 (wahab will dislike)
because the supply drop to 40 volts (not a good transformer) when loaded...so, in the reality, to maximum power swing....we gonna have plus and minus 40 volts minus the losses we usually have in the output.....so...the output swing will be around 70 volts peak to peak.
BD139 is made to 100 volts...but this does not mean that if you connect 101 volts it will explode..there are safety room...of course...the same you have in electrolitic condensers too.
Latter will open a Spartan thread to the Dx Blame ST....only schematic and some pictures, the adjustment and link to Greg site... easy to people...have not to read the big thread..... people does not like to read big threads.
Board is made using nail lacquer , because the chemical product i will use to etching attack the permanent pen traces and dissolves (dilute) the lines...i will use Hydrogen Peroxide combined with Acid...board will be glued into the heatsink...so, construction will be made in the copper side.
The thread will be "Dx Blame ST - builder's thread"
regards,
Carlos
because the supply drop to 40 volts (not a good transformer) when loaded...so, in the reality, to maximum power swing....we gonna have plus and minus 40 volts minus the losses we usually have in the output.....so...the output swing will be around 70 volts peak to peak.
BD139 is made to 100 volts...but this does not mean that if you connect 101 volts it will explode..there are safety room...of course...the same you have in electrolitic condensers too.
Latter will open a Spartan thread to the Dx Blame ST....only schematic and some pictures, the adjustment and link to Greg site... easy to people...have not to read the big thread..... people does not like to read big threads.
Board is made using nail lacquer , because the chemical product i will use to etching attack the permanent pen traces and dissolves (dilute) the lines...i will use Hydrogen Peroxide combined with Acid...board will be glued into the heatsink...so, construction will be made in the copper side.
The thread will be "Dx Blame ST - builder's thread"
regards,
Carlos
Attachments
What i dislike is people who have a wrong opinion about my opinions..
I already told you that i still use this trannies to this day.
You complain about Eva being rude, but at the same time you spread
false things about me....
Hope it was only a joke...
I already told you that i still use this trannies to this day.
You complain about Eva being rude, but at the same time you spread
false things about me....
Hope it was only a joke...
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Take a good look at post 10 dear Wahab
http://www.diyaudio.com/forums/soli...ss-i-am-trying-new-amplifier.html#post2018797
Sadly, from time to time appear someone we dislike.....because of that, forum management gave us a resource to be used...when we dislike, we install the guy into the ignore list, this way we do not need to read what they post (exception is when others quote and repeat their text).
You can use this resource to the ones you do not appreciate very much....i have three i do not appreciate....it is not too much, our forum has more than 200 thousand folks i think.
Also, if you want, i can give you links to more two comments you have made about BD139...maybe not because you dislike...maybe you like them.
regards,
Carlos
http://www.diyaudio.com/forums/soli...ss-i-am-trying-new-amplifier.html#post2018797
Sadly, from time to time appear someone we dislike.....because of that, forum management gave us a resource to be used...when we dislike, we install the guy into the ignore list, this way we do not need to read what they post (exception is when others quote and repeat their text).
You can use this resource to the ones you do not appreciate very much....i have three i do not appreciate....it is not too much, our forum has more than 200 thousand folks i think.
Also, if you want, i can give you links to more two comments you have made about BD139...maybe not because you dislike...maybe you like them.
regards,
Carlos
Attachments
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All rigth..you have asked me to stop.... and i will do it gladly
I can understand you.... not nice when people misunderstand our words, or intentions... i have experienced that too... several times....this happens.
I also do not like when people enter forum, new comers, novice in the forum, new guys...people that do not read the thread entirelly and go posting opinions, some of them not asked...people that try to redesign your amplifier when it is already made, have schematic, pictures, prototype, board layout and these things.
Also, it is not good when people do not read our profile, people do not know our age, our experience, if we are skilled or not..what we did in this life.... and not knowing, people enter the thread to teach us basic mathematics or obvious things.... absolutelly out of purpose comments.
There are several things alike..there are some folks that are demanding and want you to obbey them, to follow their instructions, agreeing or not...people that do not listen you, do not read your posts, do not follow your threads, do not have build any amplifier from you...but want you to listen them and to follow their instructions without discuss.... if you do not do what they have suggested.... then, some folks goes against you, and start to be criticising you.... you know ....alike telling you... it is alike people that say directly:
- "you have not made what i have said, ... then i will not more support you and will push you down."
Things from life ... people searching for their position, their level, their degree in their life..some folks are too much proud and not too much intelligent, as they do not believe others have a brain too...small social troubles...we can survive facing these things.
Despite these things..forum is lovely, have an enormous ammount of lovely people, friendly people.... guys that are ready to respect you... people that has some care to know you first, in advance to post things...to know what you are doing, what you have done....your profession.... well... some care to adjust the conversation level to your level, not to go making foolishes alike someone trying to teach Einstein to add 2 plus 2.
regards,
Carlos
I can understand you.... not nice when people misunderstand our words, or intentions... i have experienced that too... several times....this happens.
I also do not like when people enter forum, new comers, novice in the forum, new guys...people that do not read the thread entirelly and go posting opinions, some of them not asked...people that try to redesign your amplifier when it is already made, have schematic, pictures, prototype, board layout and these things.
Also, it is not good when people do not read our profile, people do not know our age, our experience, if we are skilled or not..what we did in this life.... and not knowing, people enter the thread to teach us basic mathematics or obvious things.... absolutelly out of purpose comments.
There are several things alike..there are some folks that are demanding and want you to obbey them, to follow their instructions, agreeing or not...people that do not listen you, do not read your posts, do not follow your threads, do not have build any amplifier from you...but want you to listen them and to follow their instructions without discuss.... if you do not do what they have suggested.... then, some folks goes against you, and start to be criticising you.... you know ....alike telling you... it is alike people that say directly:
- "you have not made what i have said, ... then i will not more support you and will push you down."
Things from life ... people searching for their position, their level, their degree in their life..some folks are too much proud and not too much intelligent, as they do not believe others have a brain too...small social troubles...we can survive facing these things.
Despite these things..forum is lovely, have an enormous ammount of lovely people, friendly people.... guys that are ready to respect you... people that has some care to know you first, in advance to post things...to know what you are doing, what you have done....your profession.... well... some care to adjust the conversation level to your level, not to go making foolishes alike someone trying to teach Einstein to add 2 plus 2.
regards,
Carlos
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Good exemple , this post....here the first line :
"BD139/140 are not the good devices to drive powers bjts at this level.."
Can you see the subtility?...
They are good enough if used for currents less than 100mA.
With higher currents, they will work, undoubtly, but the perfs
of the amp will collapse, particularly with a 4 ohm load , and
the basses won t be as energic as with higher current devices
like 2SA1837/2SC4793 pair...
That said, i agree that very good drivers are much more expensive
and difficult to source than those Beetle car like trannies..
These 2SC4792 and 2SA1837 are much better.... heheheh..made for television sets
They have low capacitance...i would love to have them here...sadly i have a single pair.
regards,
Carlos
They have low capacitance...i would love to have them here...sadly i have a single pair.
regards,
Carlos
Well, in that case, keep them preciously in a safe-deposit box
the time you find a second pair.
One never knows...
I am already listening the Dx Blame ST - 55 Volts - less than 100W at 7 ohms
Because the supply voltage drop..also the condensers are not enougth.
It is using BD139 and BD140, in the VAS position and also as drivers... because the supply voltage drop is keeping the maximum VCE swing below the maximum voltage these transistors can face.
Also, BD139 and BD140 has not obligation to explode if you increase one volt above the limits..they have no zener inside!..... they have some room..some headroom.
I am uploading a series of videos to youtube (18 videos), showing you VBEs into all transistors, currents, maximum voltage, of set, bias adjustment, frequency sweeps observed in the scope...this will take the entire day...the videos are big in data size.
Construction of audio amplifiers produces a lot of hard work, it is not something good for lazy folks..we work a lot!
Showing you, the picture, the total resistance measured in the VBE multiplier..resistance from base to emitter..the correct one to this voltage, to result in less than 50 miliamperes stand by current to each rail.
regards,
Carlos
Because the supply voltage drop..also the condensers are not enougth.
It is using BD139 and BD140, in the VAS position and also as drivers... because the supply voltage drop is keeping the maximum VCE swing below the maximum voltage these transistors can face.
Also, BD139 and BD140 has not obligation to explode if you increase one volt above the limits..they have no zener inside!..... they have some room..some headroom.
I am uploading a series of videos to youtube (18 videos), showing you VBEs into all transistors, currents, maximum voltage, of set, bias adjustment, frequency sweeps observed in the scope...this will take the entire day...the videos are big in data size.
Construction of audio amplifiers produces a lot of hard work, it is not something good for lazy folks..we work a lot!
Showing you, the picture, the total resistance measured in the VBE multiplier..resistance from base to emitter..the correct one to this voltage, to result in less than 50 miliamperes stand by current to each rail.
regards,
Carlos
Attachments
The ONLY modification done was the installation of one more output pair
Because my supply drop, these two pairs are fine...you may need more, if you have huge (good) supply.
No modifications..the same Dx Blame ST schematic...the condensers insulating voltage, of course, increased to face 55 Volts (stand by voltage...with consumption it drops a lot)
regards,
Carlos
Because my supply drop, these two pairs are fine...you may need more, if you have huge (good) supply.
No modifications..the same Dx Blame ST schematic...the condensers insulating voltage, of course, increased to face 55 Volts (stand by voltage...with consumption it drops a lot)
regards,
Carlos
Attachments
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BD139 and BD140 are 80V transistors. They are known to whitstand up to 100V, but going further is just not sensible.
+/-55V is up to 110V and rail sag is not instantaneous, it takes some time to happen, particularly when playing music. So the transistors will be subject to 110V for brief periods of time (midrange and trebble transients) no matter how much the rails are sagging with bass. They can fail.
+/-55V is up to 110V and rail sag is not instantaneous, it takes some time to happen, particularly when playing music. So the transistors will be subject to 110V for brief periods of time (midrange and trebble transients) no matter how much the rails are sagging with bass. They can fail.
Transistors are matched...the small ones are 320 of gain
BD139 and BD140 are 167 and 175 of gain.
The power transistor are 98 and 105 (NPN and PNP).
I am uploading video to youtube, 5 already uploaded, total is 18 videos (small ones)... soon i will provide you all 18 links.
If you decide to build a more powerfull version, do not forget to increase output pairs, also to increase condenser insulating voltage...the small transistors you can use 2N5401 and 2N5551, to the drivers use 2SC4793 and 2SA1837, for first VAS 2N5551 and for second VAS the 2SC4793...well..you can use the ones you want, respecting the voltage..transistors must face 120 volts (if your supply has not too much voltage drop)
regards,
Carlos
BD139 and BD140 are 167 and 175 of gain.
The power transistor are 98 and 105 (NPN and PNP).
I am uploading video to youtube, 5 already uploaded, total is 18 videos (small ones)... soon i will provide you all 18 links.
If you decide to build a more powerfull version, do not forget to increase output pairs, also to increase condenser insulating voltage...the small transistors you can use 2N5401 and 2N5551, to the drivers use 2SC4793 and 2SA1837, for first VAS 2N5551 and for second VAS the 2SC4793...well..you can use the ones you want, respecting the voltage..transistors must face 120 volts (if your supply has not too much voltage drop)
regards,
Carlos
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Multimeter gain measurements...low voltage naturally.
These chinese digital multimeters provides a gain measurement socket.....
VBE measurements...videos will show that too:
The output 540 milivolts
Drivers are 548 milivolts
Second VAS is 544 milivolts
First VAS transistor is 570 milivolts
First differential, first stage is 560 milivolts
Second differential, the feedback one is 570 milivolts
Stand by current is 44 miliamperes each rail..of set around 8 milivolts, supply voltage (without load) is 55V.... supply voltage loaded with 6 amperes...3 amperes each rail, then voltage drops to 40 plus 40 volts (reason why BD139/140 survive)
regards,
Carlos
These chinese digital multimeters provides a gain measurement socket.....
VBE measurements...videos will show that too:
The output 540 milivolts
Drivers are 548 milivolts
Second VAS is 544 milivolts
First VAS transistor is 570 milivolts
First differential, first stage is 560 milivolts
Second differential, the feedback one is 570 milivolts
Stand by current is 44 miliamperes each rail..of set around 8 milivolts, supply voltage (without load) is 55V.... supply voltage loaded with 6 amperes...3 amperes each rail, then voltage drops to 40 plus 40 volts (reason why BD139/140 survive)
regards,
Carlos
Currents.... using 55 volts supplies.
All currents are from colector to emitter:
Input CCS current is 3.277 mV
Each differential transistor 1.624 mV
Fist Vas 3.481 mV
Second VAS 9.262 mV
Drivers 4.47 mV
Output... each pair.... 10 miliamperes
regards,
Carlos
All currents are from colector to emitter:
Input CCS current is 3.277 mV
Each differential transistor 1.624 mV
Fist Vas 3.481 mV
Second VAS 9.262 mV
Drivers 4.47 mV
Output... each pair.... 10 miliamperes
regards,
Carlos
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