Attention...the gain resistor must be tweaked in an obsessive way
Inject 1Khz tone and check the output with a scope to be sure that with the same signal level the power output will be the same power.
Do not saturate your ears.... avoid sound reflections in the room....use 1 watt one meter distant (speaker)
Sit in a safe way.... or you gonna fell down from the chair.... so big gonna be the surprise after you check your evaluation referenced to the real amplifier that were playing.
You gonna be, at least, deeply surprised..... the work to build and adjust the stuff will worth as will show you something you would not believe if i try to tell you.
I use T-line speaker as standard...a 20 watt driver, 6 ohms, high compliance unit, captured from a Philips Nederland Micro System...it is soft, easy to move and go to the end of excursion with 4 volts.....so...8 volts RMS is perfect to it...no crossover installed....just a nice Brazilian silk dome tweeter feeded through a 2.2uF capacitor helping it with high frequencies...unit goes to 40 hertz without clear losses....peak may be 50 hertz....i can listen 25 hertz but not less than that...my ears have losses above 14000 hertz because i am 65 years old.... signature line has a video in portuguese language that show you the speaker, at least the picture you gonna understand.
regards,
Carlos
Inject 1Khz tone and check the output with a scope to be sure that with the same signal level the power output will be the same power.
Do not saturate your ears.... avoid sound reflections in the room....use 1 watt one meter distant (speaker)
Sit in a safe way.... or you gonna fell down from the chair.... so big gonna be the surprise after you check your evaluation referenced to the real amplifier that were playing.
You gonna be, at least, deeply surprised..... the work to build and adjust the stuff will worth as will show you something you would not believe if i try to tell you.
I use T-line speaker as standard...a 20 watt driver, 6 ohms, high compliance unit, captured from a Philips Nederland Micro System...it is soft, easy to move and go to the end of excursion with 4 volts.....so...8 volts RMS is perfect to it...no crossover installed....just a nice Brazilian silk dome tweeter feeded through a 2.2uF capacitor helping it with high frequencies...unit goes to 40 hertz without clear losses....peak may be 50 hertz....i can listen 25 hertz but not less than that...my ears have losses above 14000 hertz because i am 65 years old.... signature line has a video in portuguese language that show you the speaker, at least the picture you gonna understand.
regards,
Carlos
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I finally got all my parts to build a Dx power supply unit with a 250VA 25v toroidal transformer. The Dx PSU went together pretty nicely with four Nichicon 4700uF caps, and I since I did not have any 1mm magnet wire to make the choke, I used some extra Coilcraft flat wire 10uH inductors from my class D amps. The PSU puts out +/-37 volts and ripple was measured at 6mV with no load - pretty good I think.
Applying 37 volt rails finally allowed me to see voltage across the 0.33ohm emitter resistors. I set it for 100mA quiescent current and adjusted offset to about 1mV and it is stable.
Playing music on it now - real nice. I think I did not have enough bias before so it sounds real clean now.
Schematic of PSU:
An externally hosted image should be here but it was not working when we last tested it.
So it seems all my problems were from result of not using a high enough voltage power supply.
Thank you Carlos for a great sounding amp and clean power supply.
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I just realized that I am probably running a high bias current of 100mA. Besides added heat output, is there any issue sound quality wise from running at 100mA vs the circa recommended 10mA? Would there be less distortion with a higher bias current?
I have been listening to it for a day now at 100mA and think that this amp sounds great - excellent clarity, super bass dynamics.
I have been listening to it for a day now at 100mA and think that this amp sounds great - excellent clarity, super bass dynamics.
You mean another set of 4700uF separated by same RL? I do indeed have more (samples that I will probably not use for class D as they are so big).
So it's not bad to operate at higher bias is you can afford the heat?
Btw, I plugged in my old LM3886 (a stock board with built in dual 10,000uF caps and Burr Brown OPA2604 op amp front end) which I used to think sounded pretty nice) and there is no comparison - the Dx just kills it sound quality wise. The weight of the bass is just not there compared to the Dx. The highs are about the same possibly better with 3886. Maybe it will be relegated to a mid/tweeter amp for my active 3 way system?
So it's not bad to operate at higher bias is you can afford the heat?
Btw, I plugged in my old LM3886 (a stock board with built in dual 10,000uF caps and Burr Brown OPA2604 op amp front end) which I used to think sounded pretty nice) and there is no comparison - the Dx just kills it sound quality wise. The weight of the bass is just not there compared to the Dx. The highs are about the same possibly better with 3886. Maybe it will be relegated to a mid/tweeter amp for my active 3 way system?
Higher bias is normally better if you can afford the heat yeah. If you have those inductors sitting idle then definitely press them into service with another LC stage on the output.
The highs of the 3886 suck in my experience without serious attention to decoupling (many ceramics or low ESR caps across the supplies) and even then I prefer to use a step-down trafo to lighten the load on the amp.
The highs of the 3886 suck in my experience without serious attention to decoupling (many ceramics or low ESR caps across the supplies) and even then I prefer to use a step-down trafo to lighten the load on the amp.
The 3886 obviously can be made to be quite nice with proper attention to detail as seen in numerous examples of reference quality chip amps in the Chip Amp forum. I don't have mod86 or MyRefAmp etc to compare with. I wonder of discret class AB amps will generally have better bass authority. I think their ability to provide a large current has to be better than a chip amp if using big fat OPS transistors.
Xrk, where did you get your Dx amplifier boards? Did you get them already populated?
I thought Carlos wasn't offering any more boards.
These ones are pirates pcboards, non authorized copies
I will not provide follow up related those ones....people should search for their provider of pcboards.
I am doing something in Brazil, exclusive to Brazil, inexpensive circuits to Brazil.
https://www.youtube.com/watch?v=4op9tT6R-ac
Yes, you can use 14 volts Zener
regards,
Carlos
I will not provide follow up related those ones....people should search for their provider of pcboards.
I am doing something in Brazil, exclusive to Brazil, inexpensive circuits to Brazil.
https://www.youtube.com/watch?v=4op9tT6R-ac
Yes, you can use 14 volts Zener
regards,
Carlos
DestroyerX,
I think in many ways folks copying your board is quite a testament to how excellent they are. Imitation is the highest form of flattery. I know you did not authorize them but note that when designs are placed in the open public domain, there is not much one can do but to *expect* that people will copy them if they are good. I would say that having access to very cost effective PCB's, albeit unauthorized, has been very good for many people who do not have the means to make their own PCB's and the reach and popularity of your amp will increase by 100x vs requiring someone to make their own PCB. You have been a generous and tireless contributor and I hope you are not offended. It's been a great way for me to experience the Dx, which otherwise would not have been possible. The design is still yours and even the seller admits it - so no loss of credit in any case. Thank you for what you have done for DIY amps.
Regards,
X
I think in many ways folks copying your board is quite a testament to how excellent they are. Imitation is the highest form of flattery. I know you did not authorize them but note that when designs are placed in the open public domain, there is not much one can do but to *expect* that people will copy them if they are good. I would say that having access to very cost effective PCB's, albeit unauthorized, has been very good for many people who do not have the means to make their own PCB's and the reach and popularity of your amp will increase by 100x vs requiring someone to make their own PCB. You have been a generous and tireless contributor and I hope you are not offended. It's been a great way for me to experience the Dx, which otherwise would not have been possible. The design is still yours and even the seller admits it - so no loss of credit in any case. Thank you for what you have done for DIY amps.
Regards,
X
Thank you XRK971 by your kind words
I understand that people will search for pcboards as they want to experience the unit....and as i am not providing, it is fair for them to search wherever they are available.
I just cannot help people that made piracy, say, the one provide pcboards.... if i start to help i will be stimulating not fair and legal procedure... supporting their customer i will be helping them to do something not legal.
As a consequence i dennie to do that.... this should be the pcboard provider's job to support their customers...at the end, it is fair as they earn money selling pcboards
But i am ready to help anyone that produces pcboard by themselves in the greatest diy spirit.
Try to imagine you work hard and overhaul a beautifull old Mustang automobile...then someone copy all your flames, colour and style...will you feel yourself flattered?
Once in my life i learn something important by a forum guy that put himself "on hiatus"... he felt people had the desire to banish him....but people have not banished him..... he felt that "on the air", as a sensitive guy he decide to banish himself.... and then he posted an image "on hiatus" in the place of his picture and decide not to post anything more as a protest of something that have not happened....no effective banishment happened...but he perceived a "conspiracy" evaluating moderators action related him... he understant "against" him.
Well, at that time i have become angry with him and i said to that swedish guy:
- What a hell Swedish man!...they have not banned you !... why you behave in a such way?... this is crazy...almost stupid
He answered me and i have learned deeply:
- Uncle Charlie, you are not a swedish man, you are not inside my pants, you are not feeling what i am feeling.
regards,
Carlos
I understand that people will search for pcboards as they want to experience the unit....and as i am not providing, it is fair for them to search wherever they are available.
I just cannot help people that made piracy, say, the one provide pcboards.... if i start to help i will be stimulating not fair and legal procedure... supporting their customer i will be helping them to do something not legal.
As a consequence i dennie to do that.... this should be the pcboard provider's job to support their customers...at the end, it is fair as they earn money selling pcboards
But i am ready to help anyone that produces pcboard by themselves in the greatest diy spirit.
Try to imagine you work hard and overhaul a beautifull old Mustang automobile...then someone copy all your flames, colour and style...will you feel yourself flattered?
Once in my life i learn something important by a forum guy that put himself "on hiatus"... he felt people had the desire to banish him....but people have not banished him..... he felt that "on the air", as a sensitive guy he decide to banish himself.... and then he posted an image "on hiatus" in the place of his picture and decide not to post anything more as a protest of something that have not happened....no effective banishment happened...but he perceived a "conspiracy" evaluating moderators action related him... he understant "against" him.
Well, at that time i have become angry with him and i said to that swedish guy:
- What a hell Swedish man!...they have not banned you !... why you behave in a such way?... this is crazy...almost stupid
He answered me and i have learned deeply:
- Uncle Charlie, you are not a swedish man, you are not inside my pants, you are not feeling what i am feeling.
regards,
Carlos
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I just got blank copper clad PCB's and saw your video of how to use nail polish, hair bleach, and concrete whitener to etch my own PCB's. I think I will try the laser printer iron on method first (with nail polish as touch up) to make some more Dx power supply boards. Then move on to a more advance Dx amp. Maybe the Mk2? Anyhow, slowly getting there with home made approach.
I have also made PCB's using the mouse click method (uploading Gerber files to a shop in Singapore and robots there produce qnty 10 5cm square boards for $10 - takes 3 weeks though) which produces an absolute professional quality board but is not for the impatient.
I have also made PCB's using the mouse click method (uploading Gerber files to a shop in Singapore and robots there produce qnty 10 5cm square boards for $10 - takes 3 weeks though) which produces an absolute professional quality board but is not for the impatient.
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Dx Class, that comes from Dx Amplifier, modified and with
Full range input
Mids + Treble input
Treble - input
Subwoofer switch
100 watts 4 ohms
pcboard 53 X 93 milimeters size
Selling like bananas in an Italian street market.
Beeing sold in Brazil and also Portugal,
https://www.youtube.com/watch?v=rjQzW7fDGJY
regards,
Carlos
Full range input
Mids + Treble input
Treble - input
Subwoofer switch
100 watts 4 ohms
pcboard 53 X 93 milimeters size
Selling like bananas in an Italian street market.
Beeing sold in Brazil and also Portugal,
https://www.youtube.com/watch?v=rjQzW7fDGJY
regards,
Carlos
Member
Joined 2009
Paid Member
Member
Joined 2009
Paid Member
Here are the test point measurements you requested. This is with inputs shorted and no load of course.
Thanks!
I see you have the dummy resistor in the unused leg of the LTP. This was first investigated by member SandK many years ago. The idea was to equalize dc operating voltage at LTP collectors to equalize the affect of Early Voltage. I remain sceptical.
And still no AC bypass cap across the Vbe ? What secrets are you employing here Carlos ?
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And still no AC bypass cap across the Vbe ? What secrets are you employing here Carlos ?
If you have there a cap it will short @HF killing the idle bias, resulting in full crossover distortion.
Look i have one here but its only 220p
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A secret told is not a secret anymore
I have realised people would copy Dx Amplifier to be sold.... reason why it was made to be a little bit better than average power amplifiers, but not tuned into the maximum of it's habilities..... Dx Amplifier is working 80 percent of it's maximum performance...this way i would be one step ahead of pirates.
And happened.... thousands produced all over the world, in many countries...but all them 80 percent.
There are things supressed that are errors, and something supressed are golden solutions...there are things that should be supressed and they are in the circuit...and things that should be installed that are not in the circuit.
I still have intentions to produce the 100 percent unit..but will be done with my own industry...now a days, in Brazil, an industry will be successful if produce hand cuffs, coffins or non governmental organizations to deviate money from the state.... i will have to move outside my country to do what i want to do.... the real Dx Corporation, a Global audio enterprise.
In Brazil, dear Bigun, we have a trick to cross a river with a lot of cows.... there are many rivers, no way to build zillion bridges.....sometimes cows have to cross swiming or walking... then what is made?
We select an old cow... a sick cow... and then people produce a small cut into the animal to start some bleeding and we put it to cross the river... all Piranha fishes will go there and will transform this cow in a pile of bones in a matter of 5 minutes....bones will be entirelly and totally clean of flesh... while this is happening the herd of cows crosses with total safety.
The same was done with Dx Amplifier....it can produce better sound, more dinamics, wider bandwidth, less uncontrolled bass, less distortion and less third harmonic...as i said...it is 80 percent.... cows have crossed the river.
WWII used the same trick.... show intentions to cross the channel in one point and crossed in other point... dummy tanks, fake trucks were in fake harbors
My picture posted was taken this month...old man is very old now..but i still keep some bright deep in the eyes as i love girls deeply and i still hunt them badly, now a days aided by Viagra.
Jopseph Siejack says i am a "dirty old man"....he is right and precise.
Only one person in this world know the secret about Dx Amplifier full featured....she is my mom.... and she is not speaking anymore.... she died.
Chinese pirates may be laughing at uncle charlie..... maybe i am laughing more and loudly.... but sad at same time as i was forced to offer a 80% performer to the community because of them
"Boi de Piranha"..... Piranha's bull
regards,
Carlos
I have realised people would copy Dx Amplifier to be sold.... reason why it was made to be a little bit better than average power amplifiers, but not tuned into the maximum of it's habilities..... Dx Amplifier is working 80 percent of it's maximum performance...this way i would be one step ahead of pirates.
And happened.... thousands produced all over the world, in many countries...but all them 80 percent.
There are things supressed that are errors, and something supressed are golden solutions...there are things that should be supressed and they are in the circuit...and things that should be installed that are not in the circuit.
I still have intentions to produce the 100 percent unit..but will be done with my own industry...now a days, in Brazil, an industry will be successful if produce hand cuffs, coffins or non governmental organizations to deviate money from the state.... i will have to move outside my country to do what i want to do.... the real Dx Corporation, a Global audio enterprise.
In Brazil, dear Bigun, we have a trick to cross a river with a lot of cows.... there are many rivers, no way to build zillion bridges.....sometimes cows have to cross swiming or walking... then what is made?
We select an old cow... a sick cow... and then people produce a small cut into the animal to start some bleeding and we put it to cross the river... all Piranha fishes will go there and will transform this cow in a pile of bones in a matter of 5 minutes....bones will be entirelly and totally clean of flesh... while this is happening the herd of cows crosses with total safety.
The same was done with Dx Amplifier....it can produce better sound, more dinamics, wider bandwidth, less uncontrolled bass, less distortion and less third harmonic...as i said...it is 80 percent.... cows have crossed the river.
WWII used the same trick.... show intentions to cross the channel in one point and crossed in other point... dummy tanks, fake trucks were in fake harbors
My picture posted was taken this month...old man is very old now..but i still keep some bright deep in the eyes as i love girls deeply and i still hunt them badly, now a days aided by Viagra.
Jopseph Siejack says i am a "dirty old man"....he is right and precise.
Only one person in this world know the secret about Dx Amplifier full featured....she is my mom.... and she is not speaking anymore.... she died.
Chinese pirates may be laughing at uncle charlie..... maybe i am laughing more and loudly.... but sad at same time as i was forced to offer a 80% performer to the community because of them
"Boi de Piranha"..... Piranha's bull
regards,
Carlos
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..but i still keep some bright deep in the eyes as i love girls deeply and i still hunt them badly, now a days aided by Viagra.
Jopseph Siejack says i am a "dirty old man"....he is right and precise.
bahhahah dont stop love girls
love girls and live forever. why limited life, isn't it ? bahahah, you killed her for the secret ?
bhahahah, regards !
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