First test at the analog side , distortion figure is not bad but could be improved I think , I found that part of the signal ( -35 dBV ) is floowing back to the + 5 v supply througt the 2 ma biaising circuit
this graph shows secondaries in parallel , in series I have 1.3 v rms , distortion is about the same
.
this graph shows secondaries in parallel , in series I have 1.3 v rms , distortion is about the same
.
Last edited:
I let the all thing break-in , especially for the dem caps , their leakage goes down to nearly few nano amps after few hours
I put an 1N 4148 in the + 5v line to the biaising circuit , with an -2 dBV gain in output noise
the sound of this DAC is pretty impressive , there is no lack of anything from bottom to top , very detailed , warm and clear , no harshness
line level output is enought for my F6 and my B&W DM7
well one of the best DAC I ever heard
next step , put the all thing in a nice box
.
I put an 1N 4148 in the + 5v line to the biaising circuit , with an -2 dBV gain in output noise
the sound of this DAC is pretty impressive , there is no lack of anything from bottom to top , very detailed , warm and clear , no harshness
line level output is enought for my F6 and my B&W DM7
well one of the best DAC I ever heard
next step , put the all thing in a nice box
.
Fact is , there is no fs noise ( up to 100 Khz ) , I am supprised to for an NOS DAC without filtering
the setup is as follow , I/V resistor 75 ohm , the primary of the sowters is 3.5 ohms , and I do not have resistor in the secondaries , dc offset almost 0 mv
If i put an resistor in the secondaries ( serie or paralell ) I do have fs noise at -70 dBV
sometimes things are not as expected !!
.
the setup is as follow , I/V resistor 75 ohm , the primary of the sowters is 3.5 ohms , and I do not have resistor in the secondaries , dc offset almost 0 mv
If i put an resistor in the secondaries ( serie or paralell ) I do have fs noise at -70 dBV
sometimes things are not as expected !!
.
Last edited:
Still searching for the sweet spot , by changing the I/V resistor , with 33 ohm it gives this :
I have to go series with the secondaries because the voltage drop by a factor of two , but the distortion figures are good for such setup
strangely , for me at least , the overal resistance I/V + primary does not change that much , 3.25 ohm to 3.08 ohm
.
I have to go series with the secondaries because the voltage drop by a factor of two , but the distortion figures are good for such setup
strangely , for me at least , the overal resistance I/V + primary does not change that much , 3.25 ohm to 3.08 ohm
.
After some listening it appears some more details and tones details , it is subtile but so it is , it seems that the sweet spot is there , between 75 and 33 ohm as I/V resistor with these trafos in that setup
referencing at the title of this thread , I now understand better what it means
.
referencing at the title of this thread , I now understand better what it means
.
Are the blue caps dc blockers for the trafos, if so that will greatly affect the sound as well.
Type of resistor used for I/V greatly affects sound too. Looks like you've designed the boards
for smd which will limit the choices of passive components to test. My own findings for I/V
resistors Rhopoints, AB Carbon & Shinkoh. Shinkoh provided the best sound in my set up.
Cheers
Type of resistor used for I/V greatly affects sound too. Looks like you've designed the boards
for smd which will limit the choices of passive components to test. My own findings for I/V
resistors Rhopoints, AB Carbon & Shinkoh. Shinkoh provided the best sound in my set up.
Cheers
there are no blue caps , these are jumpers for trafos secondaries selection , I have a DC biaising circuit for nulling the DC at the output
yes most of the components are smd , not the dem caps even if I soldered them like it to avoid holes in the inner ground planes
it seems that more than the type of resistor is the output voltage before the trafos that matter the most , but once I found the right value of them I will try some different type too
.
yes most of the components are smd , not the dem caps even if I soldered them like it to avoid holes in the inner ground planes
it seems that more than the type of resistor is the output voltage before the trafos that matter the most , but once I found the right value of them I will try some different type too
.
My bad couldn't make out that blue thingy.
I don't do smd coz old fart can't see small stuff lol. More important is good stuff for audio are generally through hole varieties.
I use a line output trafo too on my Aya but it's a bigger as it can handle 60ma of current. As we tweak & experiment, one will discover strange things like for example caps, I've always found 50v version of the same value over the 16 or 25v types to sound much better.
Cheers
I don't do smd coz old fart can't see small stuff lol. More important is good stuff for audio are generally through hole varieties.
I use a line output trafo too on my Aya but it's a bigger as it can handle 60ma of current. As we tweak & experiment, one will discover strange things like for example caps, I've always found 50v version of the same value over the 16 or 25v types to sound much better.
Cheers
Not really no
Perhaps decades ago but not anymore. But has it's flaws, as trough hole, though i like it's benefits more. With technology getting cheaper by the day, you can buy really usable microscopes for even the tiniest of smd caps and resistors. Though there is no need to go lower than 0805 for diy. Main issue i see with people is the lack of will or "cojones" to try it 😁Yes perhaps your right as well. Me old n frm old school guess I feel more comfortable doing it the old way. Also I'm a compulsive tweaker & experimenter, I will try different stuff at one location to see if there's an improvement or not. Case in point I/V resistors, I tried like 9 types before I settled on Shinkoh & that wasn't the end, read that 2 watts Shinkoh sounded best so it started with 1/2, 1 n finally 2 watt version. Lol
Has anyone build this I/V stage, looks interesting : https://www.mvaudiolabs.com/digital/tda1541-iv-stage-options/
Hi all,
I tried to design a PCB board for twin TDA1541A, figuring out it's easier to deal with grounds on one board then connect grounds of two separate boards.
I'm not sure if my strategy is right:
a) I have six independent powersupplies, providing +-5,-15V to both chips idependently
b) I connected respective grounds on all three planes where I have them, leaving all the vias around pins 5 and attenuators around the chips. I hope the loops that this creates are harmless? Any comments much appreciated
Here are the tracks [Apologies for poor quality, could not find how to export JPG from the CircuitMaker]:
1) DGND, the brown pour, Layer 2. Small dots are vias
2) GND of -15V (the cyan pour on the bottom), layer #3:
3) AGND, bottom layer (#4), blue pour. I tried to connect the grounds, keeping the returns of DEM caps separated:
I tried to design a PCB board for twin TDA1541A, figuring out it's easier to deal with grounds on one board then connect grounds of two separate boards.
I'm not sure if my strategy is right:
a) I have six independent powersupplies, providing +-5,-15V to both chips idependently
b) I connected respective grounds on all three planes where I have them, leaving all the vias around pins 5 and attenuators around the chips. I hope the loops that this creates are harmless? Any comments much appreciated
Here are the tracks [Apologies for poor quality, could not find how to export JPG from the CircuitMaker]:
1) DGND, the brown pour, Layer 2. Small dots are vias
2) GND of -15V (the cyan pour on the bottom), layer #3:
3) AGND, bottom layer (#4), blue pour. I tried to connect the grounds, keeping the returns of DEM caps separated:
Congratulations @fabrice63 ! I also plan to use coupling transformers, I have very good Jensen 1:8 SUT's. I'm planning to get rid of the 2mAdc bias by going differential but perhaps a biasing circuit returned to +5V is enough. Care to share your circuit? I presume it's something more than just a resistor?
Also, what regulators are you using? I was thinking of Tentlabs shunts
Also, what regulators are you using? I was thinking of Tentlabs shunts
If I were to use coupling transformers, what values and type am I looking for? There's so many out there from UTC, Triad, Altec. Plus there's https://cinemag.biz/ and https://ivxformers.com/ ivx has tested a set with the TDA1541 per his diyaudio post
@phixphi , regulators are from LDOVR LT 3045 modules , no need of shunt stuff here , I am on Lipo battery power
tha analog output are simple I/V resistors at the primary and before the biaising circuit , I have no filtering with no FS noise up to the Mhz region
the schematics are given by John all along this thread , I2S to simultaneous at 2.5 v and Dem 50 Hz , dem cap return to the input of the -15 v reg with NO other connexions
the impedance of all the digital traces and vias are 50 ohms , the analogs are 75 ohms
for best measurement and listening result , keep the TDA output in the 50 mv region
take a very good care of your stackup and impedance , it's the key for best results
.
tha analog output are simple I/V resistors at the primary and before the biaising circuit , I have no filtering with no FS noise up to the Mhz region
the schematics are given by John all along this thread , I2S to simultaneous at 2.5 v and Dem 50 Hz , dem cap return to the input of the -15 v reg with NO other connexions
the impedance of all the digital traces and vias are 50 ohms , the analogs are 75 ohms
for best measurement and listening result , keep the TDA output in the 50 mv region
take a very good care of your stackup and impedance , it's the key for best results
.