Dear Phong...i do not know exaclty..but maybe your mains voltage is dropping too much
This way your supply voltage (and power) reduces.... this way the mains noise may appear.
About this effect, as beeing a defect..really i had not that experience with the Dx Amplifier..first time i listen that.
But it is good to know, in special if you discover the reason why.... will be a very good information to all of us.
Plug a AC voltimeter, an analogic one, and you may see voltage variations from your mains..let it there while listening and observe if this happens (the mains noise) when you have low mains voltage.
Other possibility is failure into the bias circuit because of cold solder joint...for instance, if you have the 2K2 resistance (or 2K) disconnected because bad solder, the current consumed goes very high..goes to the limtis you supply can give... check your solders.
Cold solder joints sometimes we perceive shaking the circuit board..sometimes not!..the better idea is to solder all the circuit once again to see all solder joints brigth...if they pops... bubbles going out from the solder joints..then there's the trouble you HAD.
regards,
Carlos
This way your supply voltage (and power) reduces.... this way the mains noise may appear.
About this effect, as beeing a defect..really i had not that experience with the Dx Amplifier..first time i listen that.
But it is good to know, in special if you discover the reason why.... will be a very good information to all of us.
Plug a AC voltimeter, an analogic one, and you may see voltage variations from your mains..let it there while listening and observe if this happens (the mains noise) when you have low mains voltage.
Other possibility is failure into the bias circuit because of cold solder joint...for instance, if you have the 2K2 resistance (or 2K) disconnected because bad solder, the current consumed goes very high..goes to the limtis you supply can give... check your solders.
Cold solder joints sometimes we perceive shaking the circuit board..sometimes not!..the better idea is to solder all the circuit once again to see all solder joints brigth...if they pops... bubbles going out from the solder joints..then there's the trouble you HAD.
regards,
Carlos
Thank you for the informations my friend!
Not trouble that I am slightly offtopic? (Is disappearing so, as if this would be a some kind of illness at me.)
I know that the broadcasting is not a strange thing for you.
Look, what I found: (Finally this is do-it-yourself.)
BA1404 - HI-FI Stereo FM Transmitter 88 - 108 MHz
BA1404 IC is cca. 2 dollar at us.
http://www.hqelektronik.hu/datasheet/1/168.pdf
What is your opinion?
With many thanks:
Gyuri
Not trouble that I am slightly offtopic? (Is disappearing so, as if this would be a some kind of illness at me.)
I know that the broadcasting is not a strange thing for you.
Look, what I found: (Finally this is do-it-yourself.)
BA1404 - HI-FI Stereo FM Transmitter 88 - 108 MHz
BA1404 IC is cca. 2 dollar at us.
http://www.hqelektronik.hu/datasheet/1/168.pdf
What is your opinion?
With many thanks:
Gyuri
Build and enjoy a Dx amplifier...i ensure you will never regret about that.
Have a good moments provided you by the Dx Corporation (exists only in my dreams)
regards,
Carlos
Have a good moments provided you by the Dx Corporation (exists only in my dreams)
regards,
Carlos
An externally hosted image should be here but it was not working when we last tested it.
Listen the Dx amplifier, this time three amplifiers inside same case, the Dx TriAmp
playing and recording was made using Panasonic electret condenser microphone cartridge WM-61.
There are some noises, vibrations, bad room acoustics, hum from microphone cable, but even this way you gonna feel the "spirit" of the triple amplification.
regards,
Carlos
YouTube - Dx amplifier, triple amp playing, mic. audio rec.
playing and recording was made using Panasonic electret condenser microphone cartridge WM-61.
There are some noises, vibrations, bad room acoustics, hum from microphone cable, but even this way you gonna feel the "spirit" of the triple amplification.
regards,
Carlos
YouTube - Dx amplifier, triple amp playing, mic. audio rec.
Attachments
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This one was made customized to Taj and Soundbuster
Both of them have the needed transformers for 70 volts symetrical.
Was tested and it is working fine and stable, sounding great and pumping more than 300 watts at 4 ohms.
Also i have tested using 80 volts and had 185 watts rms into 8 ohms.
Good waveshapes into the scope, very flat and distortion is reasonable.
Square wave is fine till 25 kilohertz.
Sinus started to be a triangle above 50 kilohertz.
Built and TESTED!.... guaranteed... also is a Dx amplifier with small modifications.
The drivers i have used the 2SC4793 and 2SA1837.... to the VAS i have used
2SC4793, the output was 4315 and 4215.
regards,
Carlos
Both of them have the needed transformers for 70 volts symetrical.
Was tested and it is working fine and stable, sounding great and pumping more than 300 watts at 4 ohms.
Also i have tested using 80 volts and had 185 watts rms into 8 ohms.
Good waveshapes into the scope, very flat and distortion is reasonable.
Square wave is fine till 25 kilohertz.
Sinus started to be a triangle above 50 kilohertz.
Built and TESTED!.... guaranteed... also is a Dx amplifier with small modifications.
The drivers i have used the 2SC4793 and 2SA1837.... to the VAS i have used
2SC4793, the output was 4315 and 4215.
regards,
Carlos
Attachments
Taj and Soundbuster custom schematic, Dx Amplifier to operate from 60 to 85 volts
Of course, i knew they have the transformers needed..they do not have to assemble, this is up to them, but, as they are lovely friends, i have built and tested to see if everything would gonna be all rigth.
Passed!...aproved!....Guaranteed!
Enjoy Dx amplifier, lovely friendly amplifier for your enjoyment!
Here you have a recording made using Microphone, a Panasonic electret condenser cartridge, WM-61 model:
YouTube - Dx amplifier, Taj and soundbuster unit.mpg
regards,
Carlos
Of course, i knew they have the transformers needed..they do not have to assemble, this is up to them, but, as they are lovely friends, i have built and tested to see if everything would gonna be all rigth.
Passed!...aproved!....Guaranteed!
Enjoy Dx amplifier, lovely friendly amplifier for your enjoyment!
Here you have a recording made using Microphone, a Panasonic electret condenser cartridge, WM-61 model:
YouTube - Dx amplifier, Taj and soundbuster unit.mpg
regards,
Carlos
No pcb for this amplifier, basically it is the Dx amplifier with more output
transistors, so the Dx Amplifier board will fit to place the first output pair, the other must be done using home made board or point ot point wiring.
Some values may change, but is a matter of substitute those ones, to cut a trace to include the extra diode (positive rail), or not to include the one, also the ouput emitter is a matter to cut a trace under the board and the output coils is placed hidden under the board too.
A real Do it youself, nothing as kit form to this project, because it is a variation of the old and good Dx amplifier that you have into Greg pages.
http://users.tpg.com.au/users/gerskine/dxamp/
You do not talk too much dear Black, if i decide to behave the same (alike old telegraphy, not wasting too much words because costs) will be confused, a deaf and a mute conversation.
regards,
Carlos
transistors, so the Dx Amplifier board will fit to place the first output pair, the other must be done using home made board or point ot point wiring.
Some values may change, but is a matter of substitute those ones, to cut a trace to include the extra diode (positive rail), or not to include the one, also the ouput emitter is a matter to cut a trace under the board and the output coils is placed hidden under the board too.
A real Do it youself, nothing as kit form to this project, because it is a variation of the old and good Dx amplifier that you have into Greg pages.
http://users.tpg.com.au/users/gerskine/dxamp/
You do not talk too much dear Black, if i decide to behave the same (alike old telegraphy, not wasting too much words because costs) will be confused, a deaf and a mute conversation.
regards,
Carlos
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...was in China for more than 2 years. But I am back home again.
And now? Working to hard, gaining weight... and if I find time, then I am designing on my new class D.
Just a few days ago I published one functional block of that project - the speaker relay with MosFets. But I am obviously the one & only nerd here, who wants to substitute the mechanical relays.
And now? Working to hard, gaining weight... and if I find time, then I am designing on my new class D.
Just a few days ago I published one functional block of that project - the speaker relay with MosFets. But I am obviously the one & only nerd here, who wants to substitute the mechanical relays.
People, here in Brasil, are buiding the Dx amplifier
YouTube - DX Amplifier Standard
This one built a long time ago, i have not published because the audio recorded quality is not fine...but i change my mind....well, depending the recording quality, the master quality, or the speaker quality, all amplifiers can reproduce a not so good sound too..of course they can.
regards,
Carlos
YouTube - DX Amplifier Standard
This one built a long time ago, i have not published because the audio recorded quality is not fine...but i change my mind....well, depending the recording quality, the master quality, or the speaker quality, all amplifiers can reproduce a not so good sound too..of course they can.
regards,
Carlos
Dx amplifier, to the next year of 2010 will be a green amplifier
It is not not only a good sounding amplifier, not only reliable and guaranteed,
It also saves energy...iddle power consumption is 2.4 watts with the meter lamp off.
regards,
Carlos
.................................................................................................................
DIY Dx enclosure, made using MDF cutted in rectangular pieces and glues one over the other, in layers, was used nails and white glue (school glue, student latex glue), have receive sealant to make the mdf waterproof, and them painted using a mix of plaster, latex wall paint (ink) and colour pigments... the paint material looks alike tooth paste, high density material, and them while painting and waiting the material to dry, use a brush, hit with a brush to produce that finishment you see...looks organic, this way you may keep small errors, misalignment, hidden to the eyes..brigh finishment shows all imperfections.
It is not not only a good sounding amplifier, not only reliable and guaranteed,
It also saves energy...iddle power consumption is 2.4 watts with the meter lamp off.
regards,
Carlos
.................................................................................................................
DIY Dx enclosure, made using MDF cutted in rectangular pieces and glues one over the other, in layers, was used nails and white glue (school glue, student latex glue), have receive sealant to make the mdf waterproof, and them painted using a mix of plaster, latex wall paint (ink) and colour pigments... the paint material looks alike tooth paste, high density material, and them while painting and waiting the material to dry, use a brush, hit with a brush to produce that finishment you see...looks organic, this way you may keep small errors, misalignment, hidden to the eyes..brigh finishment shows all imperfections.
Attachments
Last edited:
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