hi all
i am currently building the tnt convertus dac.
it can be found at tnt website
i finished wiring up the 3 psu and tested them.
then i hooked up the receiver and dac circuit. the dac power supply's FET (IRF830) went very hot. i immediately switched it off.
do TDA1543 implementations of the DAC portion typically have pins 5, 6, 7 and 8 all in continuity with each other? this is what i get when i tested with a multi-meter.
any help would be great.
thanks.
i am currently building the tnt convertus dac.
it can be found at tnt website
i finished wiring up the 3 psu and tested them.
then i hooked up the receiver and dac circuit. the dac power supply's FET (IRF830) went very hot. i immediately switched it off.
do TDA1543 implementations of the DAC portion typically have pins 5, 6, 7 and 8 all in continuity with each other? this is what i get when i tested with a multi-meter.
any help would be great.
thanks.
just an update.
i am still troubleshooting my dac circuit, but it seems like there are some connection caused by the solder joint between tracks of the board.
currently pins 5,6,7 and 8 do not have continuity between each other.
on some pins the multimeter will short and then show an open circuit. (could be due to caps connected to that pin)
i still have to find out where the continuity on pin 4 to 6 is. pin 4 is analog ground of the dac and pin 6 is the audio left output.
i am still troubleshooting my dac circuit, but it seems like there are some connection caused by the solder joint between tracks of the board.
currently pins 5,6,7 and 8 do not have continuity between each other.
on some pins the multimeter will short and then show an open circuit. (could be due to caps connected to that pin)
i still have to find out where the continuity on pin 4 to 6 is. pin 4 is analog ground of the dac and pin 6 is the audio left output.
you could go to Doede Duama's web site and order a printed circuit board for 20.00 U.S. Doede makes available all of the required parts....I powered mine from a 12 volt gel cell (for the DAC Tower that Draws almost half an amp) and 3 sets of Ni Cad batteries (for the reciever analog and digital supply and the clock) for a total of 4 supplies.
Sounds unbelievably good...and follows the TNT webb site ideas pretty closely.
just look up dddac 1543
Sounds unbelievably good...and follows the TNT webb site ideas pretty closely.
just look up dddac 1543
hi audionut
thanks for the advice.
i will order one from him if i fail to implement my p2p dac circuit.
right now everything seems ok, but when powered on without the dac chips so that i could measure voltage, i get abt the same voltage reading on pin 6 (audio left out) as on pin 5 (V+). while on pin 8 (audio right out), i get about 10 times less that value.
i've checked my wirings on pins 6 and 8 and could not spot any difference. will re-check when i am not so tired.
thanks for the advice.
i will order one from him if i fail to implement my p2p dac circuit.
right now everything seems ok, but when powered on without the dac chips so that i could measure voltage, i get abt the same voltage reading on pin 6 (audio left out) as on pin 5 (V+). while on pin 8 (audio right out), i get about 10 times less that value.
i've checked my wirings on pins 6 and 8 and could not spot any difference. will re-check when i am not so tired.
Hi Garbage,
the two exits should bedefinitely at the same level, if I remember correctly 0V, without the DAC chips...
There must be something still wrong somewhere, if you get such a difference...
Good Luck, and please let meknow your impressions.
Kind regards
giorgio@tnt-audio.com
the two exits should bedefinitely at the same level, if I remember correctly 0V, without the DAC chips...
There must be something still wrong somewhere, if you get such a difference...
Good Luck, and please let meknow your impressions.
Kind regards
giorgio@tnt-audio.com
hi giorgio
thanks for your reply.
i did manage to get the dac working at last, but only on one channel.
in the course of troubleshooting, i removed 2 of the 4 dacs from the parallel configuration to make it easier to spot the problem.
i managed to have it running with 2 dac instead. the sound is not good. there seem to be echos what a track is played. when one of the dac is removed, everything sounds fine.
it seems that paralleling the dac with wires soldered point to point is not ideal (there are many different lengths). maybe this caused the signal to reach the outputs (pin 6/8) at a slight delay, thereby causing the echo.
also, the noise level is not low. i just came back from a diy gathering. there were several non oversampling dacs in a shootout. there were 2 dacs that uses nimh batteries, one with a tube buffer, and the fourth, i'm not too sure of the configuration. all had their good points. i am also impressed by the compactness and neat soldering of the components.
i am in the midst of soldering a new board with just one dac for testing. this board uses most of the parts mentioned in the dac schematic on tnt, except the low pass filter using 680pf caps and the 680ohm resistor. i also removed the 1uH choke that is in series at right and left output. i have also taken care in making the board neat. hope this will bring down the noise level somewhat.
will keep you informed of the progress.
thanks for your reply.
i did manage to get the dac working at last, but only on one channel.
in the course of troubleshooting, i removed 2 of the 4 dacs from the parallel configuration to make it easier to spot the problem.
i managed to have it running with 2 dac instead. the sound is not good. there seem to be echos what a track is played. when one of the dac is removed, everything sounds fine.
it seems that paralleling the dac with wires soldered point to point is not ideal (there are many different lengths). maybe this caused the signal to reach the outputs (pin 6/8) at a slight delay, thereby causing the echo.
also, the noise level is not low. i just came back from a diy gathering. there were several non oversampling dacs in a shootout. there were 2 dacs that uses nimh batteries, one with a tube buffer, and the fourth, i'm not too sure of the configuration. all had their good points. i am also impressed by the compactness and neat soldering of the components.
i am in the midst of soldering a new board with just one dac for testing. this board uses most of the parts mentioned in the dac schematic on tnt, except the low pass filter using 680pf caps and the 680ohm resistor. i also removed the 1uH choke that is in series at right and left output. i have also taken care in making the board neat. hope this will bring down the noise level somewhat.
will keep you informed of the progress.
updates to the dac section.
there is a regular hi-frequency buzz on the speakers when using the dac.
also, the output stage is not able to drive my passive preamp even when the voltage is raised to 8V for the dac. there was no difference from 5V to 8V, volume did not increase.
any ideas on what might be wrong?
my current L and R pins are as follows:
pin ---3.3R--- 0.47uF solen --- RCA out
| |
+10uF brandless poly+
original config as suggested by tnt-convertus dac:
pin -+-----+--1mH inductor---3.3R--+---+--0.47uF+--- RCA out
| | | | |
| | | +-10uF--+
680pF 680R 1nF
| | |
G G G
lines did not come out correct....
hope you guys can decipher it.
there is a regular hi-frequency buzz on the speakers when using the dac.
also, the output stage is not able to drive my passive preamp even when the voltage is raised to 8V for the dac. there was no difference from 5V to 8V, volume did not increase.
any ideas on what might be wrong?
my current L and R pins are as follows:
pin ---3.3R--- 0.47uF solen --- RCA out
| |
+10uF brandless poly+
original config as suggested by tnt-convertus dac:
pin -+-----+--1mH inductor---3.3R--+---+--0.47uF+--- RCA out
| | | | |
| | | +-10uF--+
680pF 680R 1nF
| | |
G G G
lines did not come out correct....
hope you guys can decipher it.
From my experinece you will need a real preamp, and can´t drive a volume pot direct with the TDA1543. I would not use to much voltage, try 5V. I´m not sure many devices is parallel necessarily are better than only one. I got noise like you describe in connection with wrong values of resistor from Iout to GND and Vref to GND. Good results( with one chip) i got with something like 100 or 200R at Vref and 1100R for Iout. But i also was told this values are terribly wrong....
hi Bernhard and till
thanks for the input.
i have added 680R for pin 6 and 8 to Ground. now i don't need to turn the volume of my passive-pre too much, but max is still required to real loud listening levels.
seems like the buzzing noise would be the resistor values at Vref and between pins 6/8 to ground. after adding the 680R for those pins, the buzzing is not as noticeable except at loud volumes.
i'll build a nonoz dac portion of the circuit to compare with my current one. will do that at a later date. will keep you guys posted as well.
cheers.
thanks for the input.
i have added 680R for pin 6 and 8 to Ground. now i don't need to turn the volume of my passive-pre too much, but max is still required to real loud listening levels.
seems like the buzzing noise would be the resistor values at Vref and between pins 6/8 to ground. after adding the 680R for those pins, the buzzing is not as noticeable except at loud volumes.
i'll build a nonoz dac portion of the circuit to compare with my current one. will do that at a later date. will keep you guys posted as well.
cheers.
Hi Garbage,
the buzzing sound is puzzling me a little.... I have never had any serious problem of that kind.
I would not suggest using the Convertus for driving low impedance passive pre-amps, but it should work provided the input is 47K or more.
If you are sure everything is now ok with respect to the original convertus design, you should even unfortunately take into account the possibility that one or more of your 1543 have got burned up by during previous tests with connection problems. The fact that they were in parallel does not grants that they have all broken down in the same way, by the way: once I had to substitute one single DAC chip in the Convertus, and never understood why....
Hi Andrea,
thank you for your welcome.
Sorry for not answering to your previous message on another thread, I just run over it months later than the thread was abandoned. I am from Milan too, I think we could find a way to meet... you have my e.mail.
Kind regards to everyone
Giorgio
the buzzing sound is puzzling me a little.... I have never had any serious problem of that kind.
I would not suggest using the Convertus for driving low impedance passive pre-amps, but it should work provided the input is 47K or more.
If you are sure everything is now ok with respect to the original convertus design, you should even unfortunately take into account the possibility that one or more of your 1543 have got burned up by during previous tests with connection problems. The fact that they were in parallel does not grants that they have all broken down in the same way, by the way: once I had to substitute one single DAC chip in the Convertus, and never understood why....
Hi Andrea,
thank you for your welcome.
Sorry for not answering to your previous message on another thread, I just run over it months later than the thread was abandoned. I am from Milan too, I think we could find a way to meet... you have my e.mail.
Kind regards to everyone
Giorgio
One more note: the Convertus prototype is completely wired, so the different length of connection is not a cause for sensible misalignment of DACs or echoes.
In any case, the shortest path the better. In the prototype, all DAC chips and related components are packed in a line in less then 6cm... and wiring that has been a nice sort of nightmare that I would not like too much to repeat...
Giorgio
In any case, the shortest path the better. In the prototype, all DAC chips and related components are packed in a line in less then 6cm... and wiring that has been a nice sort of nightmare that I would not like too much to repeat...
Giorgio
hi giorgio
thanks for your comments. (always good to hear from the maker of tnt-convertus dac)
i have added the 680R to ground on pins 6/8. volume is more managable now. the buzzing also is less severe.
currently i have only the 680R, the 3.3R and the output caps. on pins 6/8.
i wonder if adding the 680pF caps will help reduce the buzzing... will try that later this week.
after i scrapped my 4 paralleled dac board, i also do not wish to attempt it the 3rd time. it is really tedious to wire up.
i am still keeping the PSUs and the receiver sections. so this point onwards, i am going to try out different configurations of the dac design.
cheers.
thanks for your comments. (always good to hear from the maker of tnt-convertus dac)
i have added the 680R to ground on pins 6/8. volume is more managable now. the buzzing also is less severe.
currently i have only the 680R, the 3.3R and the output caps. on pins 6/8.
i wonder if adding the 680pF caps will help reduce the buzzing... will try that later this week.
after i scrapped my 4 paralleled dac board, i also do not wish to attempt it the 3rd time. it is really tedious to wire up.
i am still keeping the PSUs and the receiver sections. so this point onwards, i am going to try out different configurations of the dac design.
cheers.
hi till
pin 7 is 330R to ground.
with pins 6/8 using a 680R to ground.
i realised that this config is for 4 dacs. i'll stack up the dacs for a quick try when i get home tonight.
will report my listenings later.
pins 6/8 also has a 3K3 in series after the 680R, but before the caps.
any idea what purpose the 3K3 serves?
cheers
pin 7 is 330R to ground.
with pins 6/8 using a 680R to ground.
i realised that this config is for 4 dacs. i'll stack up the dacs for a quick try when i get home tonight.
will report my listenings later.
pins 6/8 also has a 3K3 in series after the 680R, but before the caps.
any idea what purpose the 3K3 serves?
cheers
The value Till asked is quite important, as it sets the bias current (and it definitely sets the DC level on pins 6-8 together with the resistors attached to that pins.. what is that DC level on your DACs?).
It seems to me that your bias setting might be making the output of the TDAs hit their limit.
Remember that this DAC is a current out type, so output current has to be set properly to have it work right.
Cheers
Andrea
It seems to me that your bias setting might be making the output of the TDAs hit their limit.
Remember that this DAC is a current out type, so output current has to be set properly to have it work right.
Cheers
Andrea
The "right " value for The R at pin 7 and the values at pin 6 & 8 are related from my experience.
I would use 1100R or so at 6&8 and put a trimmer at pin7. Now adjust for best setting. If you want take the trimmer out, measure it, and put in a fixed resistor now. I did and got for the 1100R a value must be below 400R at Vref, else THD increases. But i was told at this board this value must be wrong and my TDA may be damaged. I got this with 3 different TDA1543 i tested.
For the 3k3 no idea, filter together with cap? output protection aginst to small load?
I would use 1100R or so at 6&8 and put a trimmer at pin7. Now adjust for best setting. If you want take the trimmer out, measure it, and put in a fixed resistor now. I did and got for the 1100R a value must be below 400R at Vref, else THD increases. But i was told at this board this value must be wrong and my TDA may be damaged. I got this with 3 different TDA1543 i tested.
For the 3k3 no idea, filter together with cap? output protection aginst to small load?
i read some where in diyaudio that Doede's values for one dac to start experimenting with is 1.35k Vref and 2.2k Rload at 8.5V.
so for 4 dacs it should be 330R(1.35k/4) Vref and 680R(2.2k/4) Rload.
anthony, the link for the site is
dddac
btw, after i stacked 4 dacs with 330R Vref and 680R Rload, it sounds much better and the buzzing is very slight. cannot really hear the buzz unless u stick your ear next to the tweeter.
so for 4 dacs it should be 330R(1.35k/4) Vref and 680R(2.2k/4) Rload.
anthony, the link for the site is
dddac
btw, after i stacked 4 dacs with 330R Vref and 680R Rload, it sounds much better and the buzzing is very slight. cannot really hear the buzz unless u stick your ear next to the tweeter.
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