Power supply
I see from the link above that there is a CRC power supply with a 3.3 ohm 3 watt resistor as one option.
But the intro notes say use a 10,000 uF capacitor for each rail.
It seems to me that there are 2 options for the transformer secondaries-
#1 is 25-0-25 400 VA with just capacitive filtering, and
#2 is 30-0-30 400 VA with CRC? (R = 3.3)
Is this right and which is preferred?
That said I can get the Avel transformers.
30-0-30 500 VA
25-0-25 330 VA a lot cheaper
will the 330 VA be sufficient for 2 channels?
I see from the link above that there is a CRC power supply with a 3.3 ohm 3 watt resistor as one option.
But the intro notes say use a 10,000 uF capacitor for each rail.
It seems to me that there are 2 options for the transformer secondaries-
#1 is 25-0-25 400 VA with just capacitive filtering, and
#2 is 30-0-30 400 VA with CRC? (R = 3.3)
Is this right and which is preferred?
That said I can get the Avel transformers.
30-0-30 500 VA
25-0-25 330 VA a lot cheaper
will the 330 VA be sufficient for 2 channels?
Yep...there are so much details to worry about that we can fail
....we are humans... a good idea is not to change something was hardly tested and result reliable.
Good and clever decision Igreen.
The amplifier, despite the low power (35 to 50 watts into 8 ohms depending the supply) or 70 to 90 watts into 4 ohms, also depends on the supply voltage and power) it has enormous punch that will turn you deeply impressed and satisfied.
regards,
Carlos
....we are humans... a good idea is not to change something was hardly tested and result reliable.
Good and clever decision Igreen.
The amplifier, despite the low power (35 to 50 watts into 8 ohms depending the supply) or 70 to 90 watts into 4 ohms, also depends on the supply voltage and power) it has enormous punch that will turn you deeply impressed and satisfied.
regards,
Carlos
Hola Carlinhos 🙂
We all wish you improving health
Wise words, but you know we are DIYers 😀 wish means we are always prone to try tweaks and mods which *probably* could improve our musical experience...ahemmm, I was reluctant to tell this to you because I can-t preview you reaction
...
My own DAC guru, ECdesigns created this *charge transfer* power supply for his low power circuits but I tried also on my little Class A amp, the ZCA for Zero Component Amp, with good effect so recently, I modded also my DX HRII powers supplies (without gyrator part)>
http://picasaweb.google.com/lh/photo/rOgiSl8IVgPdqOcKLPkbNA?feat=directlink
http://picasaweb.google.com/lh/photo/if0Yt3ku1R4vGDMHNErStA?feat=directlink
So the amp circuit is stock
but the PS is modded to *disconnect* mains/rectifier born noise from storage caps This increased capacitance from 13300 per rail to 26300. The gain in transparency, and low level detail is not attributable to increased capacitance only 😉
My caps are nothing especial, Pana THSA or lower...
Your amps are GREAT! 😎
Obrigado.
Mauricio
We all wish you improving health
Wise words, but you know we are DIYers 😀 wish means we are always prone to try tweaks and mods which *probably* could improve our musical experience...ahemmm, I was reluctant to tell this to you because I can-t preview you reaction
...My own DAC guru, ECdesigns created this *charge transfer* power supply for his low power circuits but I tried also on my little Class A amp, the ZCA for Zero Component Amp, with good effect so recently, I modded also my DX HRII powers supplies (without gyrator part)>
http://picasaweb.google.com/lh/photo/rOgiSl8IVgPdqOcKLPkbNA?feat=directlink
http://picasaweb.google.com/lh/photo/if0Yt3ku1R4vGDMHNErStA?feat=directlink
So the amp circuit is stock
but the PS is modded to *disconnect* mains/rectifier born noise from storage caps This increased capacitance from 13300 per rail to 26300. The gain in transparency, and low level detail is not attributable to increased capacitance only 😉 My caps are nothing especial, Pana THSA or lower...
Your amps are GREAT! 😎
Obrigado.
Mauricio
hehehhe.... no problems dear Max.
Well.... 27 plus 27 volts AC will work fine...also 25 plus 25 volts AC will work...but do not use 30 plus 30 as you will be into the limits.
You can..but you will not be SO safe using 30 plus 30 volts.
Well..so long time i cannot remember all detail and all words were said and all lines were written long time ago.
10 thousand microfarads each rail is fine.
330 VA transformer will work fine too.
Be happy my dear...enjoy your construction and the music you gonna play.
regards,
Carlos
.......................................................................................................
Max
Will visit your links and will read once again your text...reaction is a smile to see you around..you are welcome dear Maxlorenz...about your ideas, well, they are mine too...i am a tweaker..but we cannot ask that to all folks..we never know if they can do that or if they will mess the amplifier..how we can evaluate?.... how to be sure?...more safe is to ask them to obbey rules made during testing and construction, safety measurements... and after sucessfull construction, then the guy is encouraged to go deep into tweakings..but first to assemble and to put it to operate into the standards.
Carlos
Well.... 27 plus 27 volts AC will work fine...also 25 plus 25 volts AC will work...but do not use 30 plus 30 as you will be into the limits.
You can..but you will not be SO safe using 30 plus 30 volts.
Well..so long time i cannot remember all detail and all words were said and all lines were written long time ago.
10 thousand microfarads each rail is fine.
330 VA transformer will work fine too.
Be happy my dear...enjoy your construction and the music you gonna play.
regards,
Carlos
.......................................................................................................
Max
Will visit your links and will read once again your text...reaction is a smile to see you around..you are welcome dear Maxlorenz...about your ideas, well, they are mine too...i am a tweaker..but we cannot ask that to all folks..we never know if they can do that or if they will mess the amplifier..how we can evaluate?.... how to be sure?...more safe is to ask them to obbey rules made during testing and construction, safety measurements... and after sucessfull construction, then the guy is encouraged to go deep into tweakings..but first to assemble and to put it to operate into the standards.
Carlos
Wind tunnel system to cool heatsinks may be helpfull to you
Those are made of wooden plates...plywood or MDF (or other material you have available in your country) painted using varnish not to smell or to collect air fungus (môfus).
2 computer supply fan will blow air througth the tunnel..heatsinks are fixed using screws... 8 heatsinks and power transistors mounted into the 'windows" you can see... circuit board is mounted down using screws too.
This may produce a 600 continuous watts heatsink...using 8 old computer heatsinks from the junk and 2 fans...one pumping air and the other sucking air.
Fan may be noisy while working..so...you can reduce speed and noise using LM7808 voltage regulators... so... using 8 volts the fan will blow a good ammount of air and will not produce too much noise.
The air intake and exit must be in the front and back panel holes, no obstructed to avoid air flow resistance.
Sorry the image is in portuguese..but image talks by itself and not really needed to read what is written around.
The fan will increase mechanical resistance to the case when you apply force into the orange arrow direction...fan is attached into the triangle blocks or wood you see into the entrance and box exit.
600 watts of audio power, and continuous, can be used... 30 centimeters long wind tunnel..length will increase with the fan blower thickness.
Carlos
Those are made of wooden plates...plywood or MDF (or other material you have available in your country) painted using varnish not to smell or to collect air fungus (môfus).
2 computer supply fan will blow air througth the tunnel..heatsinks are fixed using screws... 8 heatsinks and power transistors mounted into the 'windows" you can see... circuit board is mounted down using screws too.
This may produce a 600 continuous watts heatsink...using 8 old computer heatsinks from the junk and 2 fans...one pumping air and the other sucking air.
Fan may be noisy while working..so...you can reduce speed and noise using LM7808 voltage regulators... so... using 8 volts the fan will blow a good ammount of air and will not produce too much noise.
The air intake and exit must be in the front and back panel holes, no obstructed to avoid air flow resistance.
Sorry the image is in portuguese..but image talks by itself and not really needed to read what is written around.
The fan will increase mechanical resistance to the case when you apply force into the orange arrow direction...fan is attached into the triangle blocks or wood you see into the entrance and box exit.
600 watts of audio power, and continuous, can be used... 30 centimeters long wind tunnel..length will increase with the fan blower thickness.
Carlos
An externally hosted image should be here but it was not working when we last tested it.
Hi DESTROYER X,
About "my" mod to PS, I will soon test it with the scope but I do not expect nothing strange.
I also have to test it with different sources because my present one is a little thin so the midrange, the beautiful sonics, as you say, are not as blooming as before...
Adding a capacitance multiplier to the PS will make the voltage lower than 32VDC for sure. Will this make trouble to VAS?
I usually listen on moderate SPL...never stress the amp nor the speakers.
Anyway, I'm more than pleased with the amps, which are used on a daily basis, even if I have not increased the bias yet. 🙂
Cheers,
M
I love that movie!
About "my" mod to PS, I will soon test it with the scope but I do not expect nothing strange.
I also have to test it with different sources because my present one is a little thin so the midrange, the beautiful sonics, as you say, are not as blooming as before...
Adding a capacitance multiplier to the PS will make the voltage lower than 32VDC for sure. Will this make trouble to VAS?
I usually listen on moderate SPL...never stress the amp nor the speakers.
Anyway, I'm more than pleased with the amps, which are used on a daily basis, even if I have not increased the bias yet. 🙂
Cheers,
M
Yes... this movie is great.... and i love also movies made by
Steven Spielberg....all them are nice... Duel is the prefered one..with the big truck trying to smash the red Chevrolet Sedan....nice that movie.
In Brazil it is called " Encurralado ".... made in the seventies i think..one of the first movies made by Steven Spielberg.
32 Volts will not bother your VAS....be happy trying new things Max.
regards,
Carlos
Steven Spielberg....all them are nice... Duel is the prefered one..with the big truck trying to smash the red Chevrolet Sedan....nice that movie.
In Brazil it is called " Encurralado ".... made in the seventies i think..one of the first movies made by Steven Spielberg.
32 Volts will not bother your VAS....be happy trying new things Max.
regards,
Carlos
Attachments
Re: Power supply
OOoooops. Hey Carlos, turns out I already bought the 330VA transformer.....LAST YEAR when I bought the boards. I found it this weekend when I stated the build. I have been busy with work so forgot that I had a bunch of parts. Solder was melted and I have started. Those Nordic DX II boards have everything very very close together.
Are there any issues with those boards that I should be aware of?
lgreen said:
OOoooops. Hey Carlos, turns out I already bought the 330VA transformer.....LAST YEAR when I bought the boards. I found it this weekend when I stated the build. I have been busy with work so forgot that I had a bunch of parts. Solder was melted and I have started. Those Nordic DX II boards have everything very very close together.
Are there any issues with those boards that I should be aware of?
No, there's no problems with Nordic boards
be carefull with yourself, as we are humans and we use to twist transistors and assemble them wrong way.
Just check your work many times...and everything gonna be all rigth.
regards,
Carlos
be carefull with yourself, as we are humans and we use to twist transistors and assemble them wrong way.
Just check your work many times...and everything gonna be all rigth.
regards,
Carlos
One more Dx Amplifier playing in this big world
This one a HRII, he said is "a working boss".... that is sounding wonderfull.
Quoydoy has made it in the US... thank you Brian.
regards,
Carlos
This one a HRII, he said is "a working boss".... that is sounding wonderfull.
Quoydoy has made it in the US... thank you Brian.
regards,
Carlos
An externally hosted image should be here but it was not working when we last tested it.
She sure is working, boss! Last night I listened to Frank Zappa's Apostrophe and Prince's Purple Rain on CD. The Zappa won a recording engineering award when it was released. All I can say is, wow Carlos, thank you so much for sharing.
I use the light bulb connected to main. Very helpful. One bias wire was loose on the board, and when I wiggled the wire, the lamp lit up. An output inductor, soldered underneath the board came loose, power supply led's were blinking and the lamp lit up real bright.
One of the heatsinked drivers was loose, and wiggling it, the lamp lights up.
So these and other mistakes were fixed and it sounds great.
I biased 80, and 87 milliamps, offset voltage 3.1 and 4.0 mv.
I noticed when one board is powered, the light flashes on power up, and goes off, but when 2 boards are powered up it flashes and the light bulb filiment has a tiny bit of light. When listening at 1/2 volume, there's a slightly brighter steady glow.
Since the light bulb is a visual fuse, is this right, that there is a small amount of power going through?
best wishes,
Brian
I use the light bulb connected to main. Very helpful. One bias wire was loose on the board, and when I wiggled the wire, the lamp lit up. An output inductor, soldered underneath the board came loose, power supply led's were blinking and the lamp lit up real bright.
One of the heatsinked drivers was loose, and wiggling it, the lamp lights up.
So these and other mistakes were fixed and it sounds great.
I biased 80, and 87 milliamps, offset voltage 3.1 and 4.0 mv.
I noticed when one board is powered, the light flashes on power up, and goes off, but when 2 boards are powered up it flashes and the light bulb filiment has a tiny bit of light. When listening at 1/2 volume, there's a slightly brighter steady glow.
Since the light bulb is a visual fuse, is this right, that there is a small amount of power going through?
best wishes,
Brian
yes the bulb tester will glow if sufficient current is passed through it.
As it starts to glow this is an indication that the filament is heating up. It means the resistance of the filament is now higher than when cold (positive temperature coefficient -PTC).
Yes, it's a sort of visual and electrical limiter (not fuse).
Once you have checked that all is working correctly, remove the tester and power the amplifier direct off the mains.
As it starts to glow this is an indication that the filament is heating up. It means the resistance of the filament is now higher than when cold (positive temperature coefficient -PTC).
Yes, it's a sort of visual and electrical limiter (not fuse).
Once you have checked that all is working correctly, remove the tester and power the amplifier direct off the mains.
Good Quoydoy... around 14 watts into stand by mode
may turn some lamps on... a very low brigth for sure..when operating it will modulate, and this is normal.... maximum volume will suck from the mains something around 200 watts.... the lamp will brigth but will reduce voltage to the amplifier supply..so..it will distort because lower voltage than needed.
In the reality the consumption is higher, as you have two transformers and the primary coil also behave as a load increasing the consumption a little.
Remove the protection lamp and you may be confident to increase your power... your heatsinks are not so big..but may be enougth for full power during a couple of minutes.
To operate full power and continuously, using 4 ohms, you gonna need a heatsink with 4 times your heatsink's area....perceive that your heatsinks are warm even without audio entering..because it one of them are dissipating around 6.3 watts without any audio beeing amplifiers..only heat from iddle stand by current.... this warmth shows the heatsink is "feeling" 6.3 watts as something enougth to increase the surface temperature...means the heatsink is small.... enougth big heatsinks does not show warm temperatures when the amplifier is into stand by mode....i hope you have your tiny ones cool (maybe depending your environment temperature)
Be happy, and thank you very much by the preference and confidence into Dx Corporation Amplifiers
The Corporation exists in my mind and heart.
And the ones have assembled belong to the staff.
regards,
Carlos
may turn some lamps on... a very low brigth for sure..when operating it will modulate, and this is normal.... maximum volume will suck from the mains something around 200 watts.... the lamp will brigth but will reduce voltage to the amplifier supply..so..it will distort because lower voltage than needed.
In the reality the consumption is higher, as you have two transformers and the primary coil also behave as a load increasing the consumption a little.
Remove the protection lamp and you may be confident to increase your power... your heatsinks are not so big..but may be enougth for full power during a couple of minutes.
To operate full power and continuously, using 4 ohms, you gonna need a heatsink with 4 times your heatsink's area....perceive that your heatsinks are warm even without audio entering..because it one of them are dissipating around 6.3 watts without any audio beeing amplifiers..only heat from iddle stand by current.... this warmth shows the heatsink is "feeling" 6.3 watts as something enougth to increase the surface temperature...means the heatsink is small.... enougth big heatsinks does not show warm temperatures when the amplifier is into stand by mode....i hope you have your tiny ones cool (maybe depending your environment temperature)
Be happy, and thank you very much by the preference and confidence into Dx Corporation Amplifiers
The Corporation exists in my mind and heart.
And the ones have assembled belong to the staff.
regards,
Carlos
Pics?
Thanks for the pictures Carlos. Do you (or anyone else) have better (close up) pics of the assembled boards? I tried to put everything in the right way and seeing the pics may help identify problems.
On my boards everything fit, the only problems were that a through hole was missing for one of the two variable resistors (inline hole in middle missing but staggered hole was there.). The zener diode holes were not big enough so I had to widen with a file.
The heat sinks from a few posts above look a little small? Or is this ok? How hot does it get?
I just have to build the power supply and order the capacitors.
DX Corp is not shy about using capacitors.
Thanks for the pictures Carlos. Do you (or anyone else) have better (close up) pics of the assembled boards? I tried to put everything in the right way and seeing the pics may help identify problems.
On my boards everything fit, the only problems were that a through hole was missing for one of the two variable resistors (inline hole in middle missing but staggered hole was there.). The zener diode holes were not big enough so I had to widen with a file.
The heat sinks from a few posts above look a little small? Or is this ok? How hot does it get?
I just have to build the power supply and order the capacitors.
DX Corp is not shy about using capacitors.
Sorry... picture not good, board not clean
But was hard to find.... this amplifier was studied long time ago..since those early days i have changed my computer twice and had hard drive damaged with a lot of images lost.
This is all i have.
regards,
Carlos
But was hard to find.... this amplifier was studied long time ago..since those early days i have changed my computer twice and had hard drive damaged with a lot of images lost.
This is all i have.
regards,
Carlos
An externally hosted image should be here but it was not working when we last tested it.
Big condensers are not needed into the pcboard
we need big condensers into the power supply.... into the audio amplifier board, 220uf units will make the work....of course, if you want, you can use bigger ones..but will waste money only.... advantage may exist if you decide to use thin and long wires from the supply to the amplifier pcboard..... using 10 inches wire or less than that, no need to decouple there using big condensers.
Why there are marks into the board saying 220 to 4700uf/50V?
Politically correct decision only!.... because forum folks pressure on me...some of them had the belief they need enormous condensers connected very close to the output transistor colectors...so.... because they have readed Doctor Self book.... because of those ones that have readed or had the belief connected to that condensers sizing, we left that option to big condensers into the board, and near the power output colectors....in the reality, more normal is to see 470uf or 1000uf beeing used there and working very well in thousands and thousands of amplifier designs.
Also people wanted to have separated supplies...you know, supplies hidden behind shelves, using their own cases, with long wires travelling from the supply case to the amplifier case.... under such condition big condensers are needed into the power amplifier board.
Also others wants to distribute capacitance between supply and board...in the place to use 10000uf each rail into the supply board, they decided to use 4700uf into the supply and 4700uf into the audio amplifier board.
BUT...into the input side, do not use bigger condensers there..because the surge of current during power on may destroy the rail series regulators (BD139 and BD140).
When we do amplifiers for our own use we are free to put things in order to make ourselves happy..but when we do for our communitty, we have to satisfy a lot of guys, and there are many kind of preferences and fashion things that belongs to season.
regards,
Carlos
we need big condensers into the power supply.... into the audio amplifier board, 220uf units will make the work....of course, if you want, you can use bigger ones..but will waste money only.... advantage may exist if you decide to use thin and long wires from the supply to the amplifier pcboard..... using 10 inches wire or less than that, no need to decouple there using big condensers.
Why there are marks into the board saying 220 to 4700uf/50V?
Politically correct decision only!.... because forum folks pressure on me...some of them had the belief they need enormous condensers connected very close to the output transistor colectors...so.... because they have readed Doctor Self book.... because of those ones that have readed or had the belief connected to that condensers sizing, we left that option to big condensers into the board, and near the power output colectors....in the reality, more normal is to see 470uf or 1000uf beeing used there and working very well in thousands and thousands of amplifier designs.
Also people wanted to have separated supplies...you know, supplies hidden behind shelves, using their own cases, with long wires travelling from the supply case to the amplifier case.... under such condition big condensers are needed into the power amplifier board.
Also others wants to distribute capacitance between supply and board...in the place to use 10000uf each rail into the supply board, they decided to use 4700uf into the supply and 4700uf into the audio amplifier board.
BUT...into the input side, do not use bigger condensers there..because the surge of current during power on may destroy the rail series regulators (BD139 and BD140).
When we do amplifiers for our own use we are free to put things in order to make ourselves happy..but when we do for our communitty, we have to satisfy a lot of guys, and there are many kind of preferences and fashion things that belongs to season.
regards,
Carlos
Thank you
Thank you, those pictures are very good for my purposes.
If your capacitor comment was to me, I was referring to the multitude of small teeny tiny capacitors. Those are the ones i'm trying to order now.
Thank you, those pictures are very good for my purposes.
If your capacitor comment was to me, I was referring to the multitude of small teeny tiny capacitors. Those are the ones i'm trying to order now.
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