Some answers....
I think you misunderstand. There are 2 options here. First option. The current source. Replace the BF245A with 2SK170. It is much better long term. With a warm dac adjust for zero at the input of the AD844. That just gets rid of the large DC offset from the dac. That is all the current source is for. If you want to go beyond that the AD844 has nulling pins. You would have to look at the datasheet. The value for the AD844 nulling circuit is 20K Ohms. The datasheet incorrectly calls out 20 Ohms as I recall. If you are using the pin 6 and want to direct couple without the series capacitor you can consider adding the nulling circuit. Otherwise it isn't necessary as Joe mentioned that offset isn't troublesome. My builds with the AD844 all measured -1.2 to -1.3 mV at pin 6. With the input current source sitting at zero. I used the Aya II schematic as a starting point. I am willing to advise you. Just tell me where you want to ultimately go.
Hi Torchwood....
...thanks a lot man for your help.Yes I misunderstud this two options.Becouse I have now already build al parts together I think I will just replace the BF245A with the 2SK170 and let the 500ohm trimmer in place and than make the offset for zero volts.I will look up into datasheet of AD844 to understand how to make the null offset.For now Im using the output capacitor so there will be no problem with dc on the output.I just look into the thread to see the option with BUF3 buffer conected to the TZ pin like you have done.Like I have say before I would try my tube buffer in this position if this is posibile just to check what would be the sound in this option to the internal buffer of AD844.
...thanks a lot man for your help.Yes I misunderstud this two options.Becouse I have now already build al parts together I think I will just replace the BF245A with the 2SK170 and let the 500ohm trimmer in place and than make the offset for zero volts.I will look up into datasheet of AD844 to understand how to make the null offset.For now Im using the output capacitor so there will be no problem with dc on the output.I just look into the thread to see the option with BUF3 buffer conected to the TZ pin like you have done.Like I have say before I would try my tube buffer in this position if this is posibile just to check what would be the sound in this option to the internal buffer of AD844.
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Yes. You got it. The 2SK170 just replaces the BF245A. The 500 Ohm trimmer is OK. If your tube buffer is really high impedance say a Megohm or more it should be OK. The BUF03 is nice in that it is a super light load so doesn't effect the "gain" resistor on pin 5. I use a nulling circuit on the BUF03 and that keeps the output at 1 mV or less. I am using transformer based filters these days so it is nice to keep the DC off the transformer.Hi Torchwood....
...thanks a lot man for your help.Yes I misunderstud this two options.Becouse I have now already build al parts together I think I will just replace the BF245A with the 2SK170 and let the 500ohm trimmer in place and than make the offset for zero volts.I will look up into datasheet of AD844 to understand how to make the null offset.For now Im using the output capacitor so there will be no problem with dc on the output.I just look into the thread to see the option with BUF3 buffer conected to the TZ pin like you have done.Like I have say before I would try my tube buffer in this position if this is posibile just to check what would be the sound in this option to the internal buffer of AD844.
Hi Dave.......
...thanks for answer.One another question.If I will stack another one AD844 on the existing one,it is corect that I must conect pins 2,3,4,5 and 7 and leave the pin 6 of the second AD844 disconected???So Im only using the output on the pin 6 from the first AD844??And when I stack another one on the second AD844(so now I have three together) I conect the same way like the second AD844 and let the pin 6 disconected to??I just ask this to go for shure ewerything will be corectly conected.Another question is ,must I change the resistor and capacitor on pin 5 when I stack the AD844 or can I leave the 1,5Kohm and 1nF cap in place??Im dealing for the first time with TDA1541A so I know I have many question.So thaks guys for all your help.I appreciate this!!
...thanks for answer.One another question.If I will stack another one AD844 on the existing one,it is corect that I must conect pins 2,3,4,5 and 7 and leave the pin 6 of the second AD844 disconected???So Im only using the output on the pin 6 from the first AD844??And when I stack another one on the second AD844(so now I have three together) I conect the same way like the second AD844 and let the pin 6 disconected to??I just ask this to go for shure ewerything will be corectly conected.Another question is ,must I change the resistor and capacitor on pin 5 when I stack the AD844 or can I leave the 1,5Kohm and 1nF cap in place??Im dealing for the first time with TDA1541A so I know I have many question.So thaks guys for all your help.I appreciate this!!
AD844 questions....
Hi audiorado, Yes. That is correct. You must float the pin 6 on the other AD844's. The bottom AD844 is the buffer stage you take the signal off of. What we are doing is paralleling the current mirror portion of the AD844's. So it is summing the current. This is good because the current mirror is operating without true global feedback. Pin 5 question.... Leave pin 5 resistor and capacitor in place. This is the "gain" resistor or termination load to set the output level. Pin 5 is TZ. A very special feature of the AD844. This is the reason this chip can sound so wonderful.Hi Dave.......
...thanks for answer.One another question.If I will stack another one AD844 on the existing one,it is corect that I must conect pins 2,3,4,5 and 7 and leave the pin 6 of the second AD844 disconected???So Im only using the output on the pin 6 from the first AD844??And when I stack another one on the second AD844(so now I have three together) I conect the same way like the second AD844 and let the pin 6 disconected to??I just ask this to go for shure ewerything will be corectly conected.Another question is ,must I change the resistor and capacitor on pin 5 when I stack the AD844 or can I leave the 1,5Kohm and 1nF cap in place??Im dealing for the first time with TDA1541A so I know I have many question.So thaks guys for all your help.I appreciate this!!
Hi Dave....
...thanks for answer.Ok now I have enough information to try stacking the AD844.In the meen time I will try to find a pair of BUF03 buffers to try out this option to and to see how this option will sound,but like I see now it will be dificult to find some buf03 buffers,do you Dave have maybe some option or do you know some store that sales this buffer from analog device?I have look on ebay and there are some sellers,but I dont know if this are original parts.And like you say the zero offset for buf03 must be done,so if I have this see corevtly in the data sheet of buf03, than I must use some 5 kohm trimmer on pin 1,5 and 7 to make the offset,its this corect??But for first now I will wait to get this four pieces of AD844 and stack this first,than i will try my tube buffer on tz pin that I have at home.Thanks Dave again for helping me to understand the story behind the TDA1541 and this output stage.Rado
...thanks for answer.Ok now I have enough information to try stacking the AD844.In the meen time I will try to find a pair of BUF03 buffers to try out this option to and to see how this option will sound,but like I see now it will be dificult to find some buf03 buffers,do you Dave have maybe some option or do you know some store that sales this buffer from analog device?I have look on ebay and there are some sellers,but I dont know if this are original parts.And like you say the zero offset for buf03 must be done,so if I have this see corevtly in the data sheet of buf03, than I must use some 5 kohm trimmer on pin 1,5 and 7 to make the offset,its this corect??But for first now I will wait to get this four pieces of AD844 and stack this first,than i will try my tube buffer on tz pin that I have at home.Thanks Dave again for helping me to understand the story behind the TDA1541 and this output stage.Rado
BUF03 source
I will have to look at the datasheet however what you mentioned on the offset adjust for the BUF03 sound correct. Dave
Send me a private message and I will give you an email address to get AD BUF03's. And you are very welcome for the help.Hi Dave....
...thanks for answer.Ok now I have enough information to try stacking the AD844.In the meen time I will try to find a pair of BUF03 buffers to try out this option to and to see how this option will sound,but like I see now it will be dificult to find some buf03 buffers,do you Dave have maybe some option or do you know some store that sales this buffer from analog device?I have look on ebay and there are some sellers,but I dont know if this are original parts.And like you say the zero offset for buf03 must be done,so if I have this see corevtly in the data sheet of buf03, than I must use some 5 kohm trimmer on pin 1,5 and 7 to make the offset,its this corect??But for first now I will wait to get this four pieces of AD844 and stack this first,than i will try my tube buffer on tz pin that I have at home.Thanks Dave again for helping me to understand the story behind the TDA1541 and this output stage.Rado
I will have to look at the datasheet however what you mentioned on the offset adjust for the BUF03 sound correct. DaveFew questions regarding the circuit in the first post
Excuse me if the answers are in this thread and I have not read all the posts.
I want to use tg\his circuit as Iv converter for the TDA 1543 chip,
!) What are the values i need to change?
2) What is the value of VR 1 ? What measurement do i get when i vary the value at VR1?
3 ) What is the optimum operating point?
thanks in advance
kp93300
Excuse me if the answers are in this thread and I have not read all the posts.
I want to use tg\his circuit as Iv converter for the TDA 1543 chip,
!) What are the values i need to change?
2) What is the value of VR 1 ? What measurement do i get when i vary the value at VR1?
3 ) What is the optimum operating point?
thanks in advance
kp93300
TDA1543
Dave
Hi, I know nothing about the TDA1543 economy DAC. If it is a current output DAC which I think it is. First step is to build the single AD844 stage. You will have to do some measuring. From that you can figure out if you need a current source to get rid of the DC offset. The Pedja AYA II DAC schematic is helpful as it shows the basic current offset nulling scheme. The TDA1541 /A chip has about 4 mA output. So you will want to check to see how much the 1543 puts out. To start with I'd probably start with the AYA II dac circuit driven by the 1543. Use the 1541 settings. See if you have enough adjustment range for nulling. Use a 2SK170 in place of the other JFET shown on the early version. It is a better part drift wise. If you just use a coupling cap at the output you could consider skipping the the offset circuit. PM me if you need the Pedja document. I can send it to you if you want to send me an email address. Sadly you will have to do some work to use with the 1543. I was given some TDA1541's so that is why I use that.
DaveTDA1543 with AD844 and 3.3V Vref, Help !
Hello,
I have made a quick setup :
Raspberry Pi (picoreplayer) USB -> Amanero
Amanero I2S -> 3K3 x3 -> pin 1,2,3 TDA1543
TDA1543 AOL pin 6 -> pin 2 AD844
TDA1543 Vref pin 7 -> NC
3V3 (TL431) -> pin 3 AD844
pin 5 AD844 -> R IV 330 Ohms to Ground
pin 6 AD844 -> 100K Ohms to Ground
pin 5 or 6 AD844 -> LM1875 NON Inverting input
I can play music with good sound, however, whatever the R IV value, I get HUGE distortion as soon has I move digital volume above 20% from the picoreplayer, don't understand why ???
TDA1543 PSU tried both 5V and 8V25 no change
AD844 PSU +/- 15V
LM1875 PSU +/- 20V
Any idea why I can't move digital volume up to 100 % ?
Hello,
I have made a quick setup :
Raspberry Pi (picoreplayer) USB -> Amanero
Amanero I2S -> 3K3 x3 -> pin 1,2,3 TDA1543
TDA1543 AOL pin 6 -> pin 2 AD844
TDA1543 Vref pin 7 -> NC
3V3 (TL431) -> pin 3 AD844
pin 5 AD844 -> R IV 330 Ohms to Ground
pin 6 AD844 -> 100K Ohms to Ground
pin 5 or 6 AD844 -> LM1875 NON Inverting input
I can play music with good sound, however, whatever the R IV value, I get HUGE distortion as soon has I move digital volume above 20% from the picoreplayer, don't understand why ???
TDA1543 PSU tried both 5V and 8V25 no change
AD844 PSU +/- 15V
LM1875 PSU +/- 20V
Any idea why I can't move digital volume up to 100 % ?
Hello,
I have made a quick setup :
Raspberry Pi (picoreplayer) USB -> Amanero
Amanero I2S -> 3K3 x3 -> pin 1,2,3 TDA1543
TDA1543 AOL pin 6 -> pin 2 AD844
TDA1543 Vref pin 7 -> NC
3V3 (TL431) -> pin 3 AD844
pin 5 AD844 -> R IV 330 Ohms to Ground
pin 6 AD844 -> 100K Ohms to Ground
pin 5 or 6 AD844 -> LM1875 NON Inverting input
I can play music with good sound, however, whatever the R IV value, I get HUGE distortion as soon has I move digital volume above 20% from the picoreplayer, don't understand why ???
TDA1543 PSU tried both 5V and 8V25 no change
AD844 PSU +/- 15V
LM1875 PSU +/- 20V
Any idea why I can't move digital volume up to 100 % ?
Could it be the picoplayer problem.? Try it on another PC.
The video market as far as I'm aware isn't affected by the 'no feedback' meme, so probably no.
I have a hypothesis that 'no feedback' isn't really to do with feedback at all, its to do with poor PSRR of opamps. Using the AD844 without the buffer means its not subject to the PSRR of the output stage and hence sounds cleaner.
Eldam you could try AD844 with feedback but with much cleaner power supplies - lots of paralleled X7R ceramics between pins4 and 7. I'm using it in such a way in my DAC and it sounds jolly clean.
Hello Abrax,
Thanks for your input.
I'm really amazed by what P Rogic made a long time ago now with the opa861 ! I'm listen to it with a TDA1541 with an AYA2 for less than one month and it sounds pretty good according to my ears !
My next experiment is about the AD1862. First with a "simple" discrete diamond for I/V board made by Painkiller member. But with 1 mA output from the chip, maybe some AD844 would be even better than BC550/560. What is puzzle me is than a smart people like P. Rogic swapped the ad844 for the 660 or 861 ! Could 2 or 3 AD844 à la George can change something here ?
I was just wondering if such video oap could be improved by any newer one here ! I even don't know if the 861 beats the 660, and why a 844 could be even better with this special à la George conf !
But sure if I try I will use your tip, small case X7R caps between pins 4&7 or stay on the opa 861... not sure a discrete can be better... or surely complex to do !
Thanks for your input.
I'm really amazed by what P Rogic made a long time ago now with the opa861 ! I'm listen to it with a TDA1541 with an AYA2 for less than one month and it sounds pretty good according to my ears !
My next experiment is about the AD1862. First with a "simple" discrete diamond for I/V board made by Painkiller member. But with 1 mA output from the chip, maybe some AD844 would be even better than BC550/560. What is puzzle me is than a smart people like P. Rogic swapped the ad844 for the 660 or 861 ! Could 2 or 3 AD844 à la George can change something here ?
I was just wondering if such video oap could be improved by any newer one here ! I even don't know if the 861 beats the 660, and why a 844 could be even better with this special à la George conf !
But sure if I try I will use your tip, small case X7R caps between pins 4&7 or stay on the opa 861... not sure a discrete can be better... or surely complex to do !
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My reasons for it.
1: Stacking the 844's lowers the input impedance (<25ohms), which multibit dacs love.
2: And also helps with any potential current saturation, that a single may have.
3: Also it has the TZ output which gives a you scope to use your own fet input high input impedance >100kohm, low output impedance buffer, such as I used with the BUF03.
4: And it's 8 pin dip, I can't see let alone solder and experiment with smd.
5: And it sounds stunning, though getting harder to source and expensive, maybe that's why they use the others.
Cheers George
1: Stacking the 844's lowers the input impedance (<25ohms), which multibit dacs love.
2: And also helps with any potential current saturation, that a single may have.
3: Also it has the TZ output which gives a you scope to use your own fet input high input impedance >100kohm, low output impedance buffer, such as I used with the BUF03.
4: And it's 8 pin dip, I can't see let alone solder and experiment with smd.
5: And it sounds stunning, though getting harder to source and expensive, maybe that's why they use the others.
Cheers George
Picoreplayer is not the problem !
Hello kp93300 ,
I use the exact same player with great success on different DAC including I2s->4 TDA1543 (muse) with passive I/V.
My suspiscion is that there might be different kind of TDA1543.
The one I used in the above mentioned setup are TDA1543A that I suspect to be kind of fake.
According to that post, there may be some differrent TDA1543 with "true" I2S and other format that need shift register
http://www.diyaudio.com/forums/digital-source/10838-tda1543a.html
Post #18
What do the experts think ?
Hello kp93300 ,
I use the exact same player with great success on different DAC including I2s->4 TDA1543 (muse) with passive I/V.
My suspiscion is that there might be different kind of TDA1543.
The one I used in the above mentioned setup are TDA1543A that I suspect to be kind of fake.
According to that post, there may be some differrent TDA1543 with "true" I2S and other format that need shift register
http://www.diyaudio.com/forums/digital-source/10838-tda1543a.html
Post #18
What do the experts think ?
Some ideas....
Well it doesn't conform to any of my setups. However if you are using a real TDA1543.... Just a couple of hints. If you are using pin 5 as an output pin on the AD844 you should float pin 6 (no connection). Your TL431 on pin 3 AD844.... Are you trying to get rid of a DC offset from the DAC? A 2SK170 set up as a current source might be better. I have used them with great results. It is puzzling.Hello,
I have made a quick setup :
Raspberry Pi (picoreplayer) USB -> Amanero
Amanero I2S -> 3K3 x3 -> pin 1,2,3 TDA1543
TDA1543 AOL pin 6 -> pin 2 AD844
TDA1543 Vref pin 7 -> NC
3V3 (TL431) -> pin 3 AD844
pin 5 AD844 -> R IV 330 Ohms to Ground
pin 6 AD844 -> 100K Ohms to Ground
pin 5 or 6 AD844 -> LM1875 NON Inverting input
I can play music with good sound, however, whatever the R IV value, I get HUGE distortion as soon has I move digital volume above 20% from the picoreplayer, don't understand why ???
TDA1543 PSU tried both 5V and 8V25 no change
AD844 PSU +/- 15V
LM1875 PSU +/- 20V
Any idea why I can't move digital volume up to 100 % ?