Jean-Paul,
Have given the transformer issue some thought. You can probably skip or make your series-resistors a lot smaller. This will make the transformer work and hopefully sound better.
The precaution with 2k a side is probably when connecting from the outputs to ground due to DC-offset.
Your transformer is built for working with a source impedance of 600ohms.
If we assume the DAC having 30-50ohm Zout a side you should then add 270ohm a side making a total of ca 600ohm.
If we also assume your transformers having an inductance of 100H they will together with the series resistors and the DCR present an AC-load of ca 4kohm at 5Hz to the DAC. Above that the overreduced secondary loading(10k should be fine) will be what loads the DAC.
Jensens application shows how to trim the diff offset to zero with the help of two 15k resistors and a 10k pot with its wiper to ground.
Have given the transformer issue some thought. You can probably skip or make your series-resistors a lot smaller. This will make the transformer work and hopefully sound better.
The precaution with 2k a side is probably when connecting from the outputs to ground due to DC-offset.
Your transformer is built for working with a source impedance of 600ohms.
If we assume the DAC having 30-50ohm Zout a side you should then add 270ohm a side making a total of ca 600ohm.
If we also assume your transformers having an inductance of 100H they will together with the series resistors and the DCR present an AC-load of ca 4kohm at 5Hz to the DAC. Above that the overreduced secondary loading(10k should be fine) will be what loads the DAC.
Jensens application shows how to trim the diff offset to zero with the help of two 15k resistors and a 10k pot with its wiper to ground.
I'm having some problems with the LCBPS and Ballsie. I'm using one single transformer for both LCDPS and LCBPS, it's a 2x 12v 2x 12VA. At first I accidently connected both inputs on the LCBPS with from the same secondary. R2 and R3 ran very hot. I fixed it and connected one from each which resulted in normal temperature also the output V was just over 16V.
I had both LCDPS and LCBPS connected at the same time and voltage outputs were correct, however when I connected all the modules R2 and R3 on the LCBPS started running hot again while the leds lit up as they should.
Do I need two separate transformers or is there something else that might be wrong?
I had both LCDPS and LCBPS connected at the same time and voltage outputs were correct, however when I connected all the modules R2 and R3 on the LCBPS started running hot again while the leds lit up as they should.
Do I need two separate transformers or is there something else that might be wrong?
jonatan_w said:
You need two separate transformers for this.You will short the ground if you share transformers.
John, the simple answer is you should use one secondary per PS output.
That said. It is possible to use a single transformer, but it requires that you make both supplies of the LCDPS share the same secondary as the positive supply on the LCBPS. Still it would be better to just add a transformer.
:EDIT: MrMajestic has the right idea. 🙂 :/EDIT:
Cheers!
Russ
That said. It is possible to use a single transformer, but it requires that you make both supplies of the LCDPS share the same secondary as the positive supply on the LCBPS. Still it would be better to just add a transformer.
:EDIT: MrMajestic has the right idea. 🙂 :/EDIT:
Cheers!
Russ
Is it possible for me to use a center-tapped transformer to power the LCBPS? Found a cheap one: http://www.electrokit.se/images/41000407.jpg
As I understand it the LCBPS joins the ground circuit wise anyway so using a center tapped should work. Also this one I might be able to fit into my current casing 🙂
As I understand it the LCBPS joins the ground circuit wise anyway so using a center tapped should work. Also this one I might be able to fit into my current casing 🙂
jonatan_w said:
It is possible, but you would not be able to use the bridges as they are.
You would need a single bridge(could be off board). then just connect the center tap to GND.
Cheers!
Russ
Bought a second transformer with dual secondaries instead. However I seem to have some "crackling" noise in one channel. The sound quality is superb but its sort of like a random taps or something, I used the OPUS without the Ballsie before without this noise so I'm guessing its the ballsie that is the problem, however I can't really figure out what to do as a solution. I changed the cables going from the DAC boards to the ballsie to better ones without it doing anything, I've tried to adjust the output of the LCBPS from +-17.2 to +-19.5 V. But so far my attempts have been in vain.
Any thoughts about what could be the problem?
Any thoughts about what could be the problem?
Well, 19.5V is way too high. The opamps are rated to 17V. Try 12-15V.
Hopefully the opamps are not dead yet.
Hopefully the opamps are not dead yet.
I can't seem to be able to lower the output on the negative to anything less than 17.3 and the positive to 16, then the put hits max and clicks.
jonatan_w said:
Get new ones... Unlikely that they are still in working order, and should they be their reliability will be questionable.
Hi
The LCBPS is working fine now, however the noise in one of the channels still remains, is it possible that something was damaged due to the high voltage?
The LCBPS is working fine now, however the noise in one of the channels still remains, is it possible that something was damaged due to the high voltage?
Very possible. Can you check the sound directly out of the Opus? Just tap +/GND from both channels, then -/GND from both channels. If that's okay, then the problem is in the Ballsie.
Its the same noise as with the ballsie. I've tried changing the cables from the SPDIF to the DACs but it didn't help. I've run the setup for quiet a while without the noise before I changed casing and added the ballsie. Listening more closely I can hear the noise in both channels however its stronger in one of the channels. The casing is pretty small so its a tight fit with transformers and parts. Any tips on things I can test to isolate the problem?
I would bet that it is interference caused by power or audio lines too close to the I2S lines. Can you post a pic of the layout? Of particular interest is the routing of the I2S lines between the receiver and the DAC.
WM8741 modes
Hi friends,
I've been delaying my first DAC project while I (do other work and) contemplate how much switching and tweaking I really want to undertake... The more I think about it, the less time/energy I seem to have! 😕 For simplicity, I was hoping to run opus board outputs directly into my balanced TXO amps.
I could use some opinions on these questions:
1. All other things equal, how much sonic difference can I expect between an Opus board running mono vs. an Opus board running stereo? Does resampling modify the difference? I have up to 8 channels to handle.
2. Have any of you implemented DSD on this chip and what are your observations? Is performance decent and what is the best configuration? I would prefer balanced outputs for 6 channels. [I have a Denon DVD 1930ci player available for mods, but haven't decided how much patience I should have for switching and controlling the operational modes. Time has really become a factor...]
Any and all comments will be most appreciated!
Frank in Minneapolis
Hi friends,
I've been delaying my first DAC project while I (do other work and) contemplate how much switching and tweaking I really want to undertake... The more I think about it, the less time/energy I seem to have! 😕 For simplicity, I was hoping to run opus board outputs directly into my balanced TXO amps.
I could use some opinions on these questions:
1. All other things equal, how much sonic difference can I expect between an Opus board running mono vs. an Opus board running stereo? Does resampling modify the difference? I have up to 8 channels to handle.
2. Have any of you implemented DSD on this chip and what are your observations? Is performance decent and what is the best configuration? I would prefer balanced outputs for 6 channels. [I have a Denon DVD 1930ci player available for mods, but haven't decided how much patience I should have for switching and controlling the operational modes. Time has really become a factor...]
Any and all comments will be most appreciated!
Frank in Minneapolis
Frank,
In my experience. While the difference between dual mono and stereo is audible and real, it is not significant. Its a matter of degrees.
The nice thing is you can start with one in stereo and try dual mono later if you choose.
Cheers!
Russ
In my experience. While the difference between dual mono and stereo is audible and real, it is not significant. Its a matter of degrees.
The nice thing is you can start with one in stereo and try dual mono later if you choose.
Cheers!
Russ
Hi, I've been following the twisted pear website for many months having a look at all the great little modules you have been developing.
I want to use computer as source with toslink spdif output. That way the dac is electrically isolated from the computer and toslink can be run very long so I can shut the computer away in another room if I want to. But what is the best way to reclock digital audio before feeding it to the dac? One option being spdif reclock like with Doede's DDDAC. Or maybe I2S reclock with the Metronome? How do they compare in terms of removing jitter?
Metronome has the added advantage of upsampling to 192 KHz (maybe the dac such as Opus or Buffalo perform better at 192 KHz?). But big disadvantage it cannot resample to 44.1 KHz. The twisted pear modular design is great... but adding up all the bits gets a wee bit expensive. So many options, so little time!
😀
I want to use computer as source with toslink spdif output. That way the dac is electrically isolated from the computer and toslink can be run very long so I can shut the computer away in another room if I want to. But what is the best way to reclock digital audio before feeding it to the dac? One option being spdif reclock like with Doede's DDDAC. Or maybe I2S reclock with the Metronome? How do they compare in terms of removing jitter?
Metronome has the added advantage of upsampling to 192 KHz (maybe the dac such as Opus or Buffalo perform better at 192 KHz?). But big disadvantage it cannot resample to 44.1 KHz. The twisted pear modular design is great... but adding up all the bits gets a wee bit expensive. So many options, so little time!
😀