This might be a good intro for you: https://doc.lagout.org/electronics/Electronics for Dummies (2005).pdf
That's a very useful tip, cheers. I happen to have a cheap EMI board from ebay, it was 1.87ukp, it's a ferrite coil with an MKP cap either side, so basically what you describe. At that price, I can add more of them where needed, haven't wired the first one up yet.
Power Supply Filtering Board 3A EMI Filter for DAC Amplifier Module Sensor Sound 656007996824 | eBay
I just hooked up my creation for the first time, it's far from finished, still lots more work to do, but I am delighted to report that it works and not only does it work, it sounds really pretty good, probably as good as the 24/96 DAC in my Yamaha DSP-E800. The sound is a little different, less bass, and the output is low so I need to crank the volume up a lot higher, but I can hear no distortion, no hiss, nothing undesirable at all, apart from a constant hum which you can only detect when there is no music playing or there is a very quiet section, should be able to fix that though, it could be because I have connected the ground of the power supply yet.
All I've done is hook the output directly to the RCAs on the rear, so there is nothing aside from a pair of Rubycon 100uF electrolytics between the DAC chip's output and the RCAs. I still need to build the circuitry for the LP filter that will connect the DAC to the output buffer, so there is no analogue stage at all, other than those DC blocking Rubycons, so I am sure there is much improvement to come.
The PSU isn't even complete either, all I've done is connect the transformer's 9v outputs to the LM317/LM337 board and then connect the output of that to the DAC board. I need to check the voltage coming out of the regulator board and tweak it to be the 5v the DAC requires, it's probably a bit high at the moment. Then I need to finish the smoothing cap board off and fit that between regulator and DAC, which should lead to further improvement in the sound.
Then there's the EMI filter board to be connected between the inlet and the transformer and the grounding wires to be sorted out, then I need to figure out how to power the output buffer, at first I'll try running it off the 15v single rail output of the current transformer, with a second LM317/337 board and set of coupling caps. However, the buffer has connections for a dual rail 15V supply, so I may end up adding a second transformer so I can give it a dual rail supply.
I'm very pleased the thing actually works and sounds so good in this rough and ready state, I can't wait to get more of the jobs to be done complete and hear how it changes the sound, I reckon I can eek quite a bit more quality out of it.
I'll take some photos in the morning, it's too dark now, sadly.
Thanks for all the advice, it is very much appreciated, and appears to be paying off as I'm actually making some progress.
It's very satisfying when a plan comes together.
I hope my dual TDA1541 balanced NOS DAC using IanCanada's I2S to simultaneous converter works & sounds as good as I am expecting.
I have just to finish the psu, using Dexa low noise regulators.
I use transformers with a gain of 6 for the output to a Quad 405-2, connected between the 47R I/V resistors. (they also act as LP filter and as the DACs are operating out of phase, much of the digital noise and rubbish cancels out in them as they are bifilar wound)
My source is an old Philips 1541 CD player with a new clock pcb and the I2S & master clock signals connected to the dac via a 1m Cat5e cable.
That sounds like a very interesting project you have there, I'd particularly like to see details of your output transformer setup.
Once I've finished this DAC project, I'll do it again but with a better DAC board and go the whole hog with toroidal transformers, BHC electrolytics, Russian PIOs etc. But I have a lot to learn first....
I don't know if I've ever heard the TDA1541, of course I know it's reputation. 90% of my listening today is FLAC files, mostly 24/96, so I'm not sure an old red book compatible DAC chip would work for me.
I've done a load more work on my DAC today, but sadly I stood on my SD card reader so no photos until a new one arrives. Yes, I'm a clumsy git!
Once I've finished this DAC project, I'll do it again but with a better DAC board and go the whole hog with toroidal transformers, BHC electrolytics, Russian PIOs etc. But I have a lot to learn first....
I don't know if I've ever heard the TDA1541, of course I know it's reputation. 90% of my listening today is FLAC files, mostly 24/96, so I'm not sure an old red book compatible DAC chip would work for me.
I've done a load more work on my DAC today, but sadly I stood on my SD card reader so no photos until a new one arrives. Yes, I'm a clumsy git!
The transformers are 9545 (superceded by 1465) from Sowter.
DAC I/V CONVERSION OUTPUT TRANSFORMERS
These are designed for current output dacs but they do also sell them for voltage output dacs.
I use them because I have tried to avoid active lp filters although some will say they add their own colour the sound.
I was looking at the Sowter website the other day actually, the prices of those transformers is a bit too rich for me, but i hope you enjoy them, they certainly have a high reputation for quality.
I don't suppose there is a cheaper option? They are just a form of isolation transformer aren't they?
I just bought a pair of NOS toroidals with dual 18v output for 7.50ukp each, made by Talema, I'm picking up parts for my eventual better DAC as I come across them cheap.
I don't suppose there is a cheaper option? They are just a form of isolation transformer aren't they?
I just bought a pair of NOS toroidals with dual 18v output for 7.50ukp each, made by Talema, I'm picking up parts for my eventual better DAC as I come across them cheap.
You can buy cheaper, but still pretty good quality Chinese transformers (sans the mu metal cans). But still not as cheap as some incredibly good opamps. And like anything else, transformers have a sound. If you like the sound, fine.
Also, you still need an amplifier after the transformer. Some amplifiers are a lot like big opamps inside. Or, some amplifiers use tubes and can even have input, interstage and output transfomers, if you *really* like the sound of transformers. Lots of choices and different ways to spend money.
Maybe good to decide if you like accuracy more or distortion more first. If you want to hear what is on a record the way it was heard in the mastering room, you should probably go for accuracy.
Also, you still need an amplifier after the transformer. Some amplifiers are a lot like big opamps inside. Or, some amplifiers use tubes and can even have input, interstage and output transfomers, if you *really* like the sound of transformers. Lots of choices and different ways to spend money.
Maybe good to decide if you like accuracy more or distortion more first. If you want to hear what is on a record the way it was heard in the mastering room, you should probably go for accuracy.
I don't know whether I will like the sound of transformers or not until I hear them.
Today I added an EMI filter, a bank of smoothing capacitors and some grounding wiring and to my surprise, the damn thing doesn't work anymore, I just get a loud buzzing and no music at all.
So tomorrow I'll have to troubleshoot it and figure out what's wrong.
Today I added an EMI filter, a bank of smoothing capacitors and some grounding wiring and to my surprise, the damn thing doesn't work anymore, I just get a loud buzzing and no music at all.
So tomorrow I'll have to troubleshoot it and figure out what's wrong.
You were fortunate that none of them exploded. Electrolytics do not like reversed polarity, they act like a short circuit, heat up and burst or worse.
If you want really cheap you can DIY your transformers using ferrite core sets (PQ26 works nicely for DAC output trafos) and magnet wire. That's what I do, but you substitute time and effort for money.
Thanks for the capacitor safety tip, luckily the polarity issue was how I'd connecting the output of the cap bank to the DAC board, so the caps should be fine.
That's interesting about the DIY transformers, I happen to have some enamelled wire left over from rewinding an old motor some years ago, so I might have to obtain a couple of ferrite cores and give it a try. I don't suppose you have posted in more detail about making these things before so I can study it?
That's interesting about the DIY transformers, I happen to have some enamelled wire left over from rewinding an old motor some years ago, so I might have to obtain a couple of ferrite cores and give it a try. I don't suppose you have posted in more detail about making these things before so I can study it?
As it happens I have posted in a fair amount of detail on this - Designing a classD amp input transformer - step by step guide
Now here's an interesting little problem. I connected this EMI filter board before the transformer:
Power Supply Filtering Board 3A EMI Filter for DAC Amplifier Module Sensor Sound 656007996824 | eBay
and all I get is a loud humming, the moment the device is plugged into the mains, which continues when the unit is switched on. Removing the EMI board from the circuit and the humming goes away.
I'm puzzled as to what's going on.
Power Supply Filtering Board 3A EMI Filter for DAC Amplifier Module Sensor Sound 656007996824 | eBay
and all I get is a loud humming, the moment the device is plugged into the mains, which continues when the unit is switched on. Removing the EMI board from the circuit and the humming goes away.
I'm puzzled as to what's going on.
So, you have the Live, Neutral, and Earth terminals on the filter board connected to your wall socket how? On the load side there is no Earth, so how do you have those terminals connected?
Can you measure resistance on the filter board from the input Live terminal to the output Live terminal? How about for the Neutral terminals?
Can you measure resistance on the filter board from the input Live terminal to the output Live terminal? How about for the Neutral terminals?
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I'll take a photo tomorrow, to show how it is connected and make some measurements as you suggest. I'm about to hit the sack, it's 2.35am here and I have the thing partially dismantled due to testing the various connections with my meter to find another problem I think I have traced to the on-off switch.
You need to connect the earth from your chassis to the E terminal on the pcb.
I am surprised there is no earth continuity from in to out.
The Earth connection is of course a safety ground. If the filter board were used inside one's chassis, then Earth would be connected to the chassis where the power cord comes in. It would also be connected to the filter input side very nearby. The output from the filter would then be connected to the power transformer primary. Something like that.
If on the other hand connecting Earth to chassis ground suddenly fixed whatever problem there currently is with nothing powering up then that would be of serious concern. Obviously, Earth should never be used to carry input power current. Just saying, to double check we are all fully in agreement on how it should work.
If on the other hand connecting Earth to chassis ground suddenly fixed whatever problem there currently is with nothing powering up then that would be of serious concern. Obviously, Earth should never be used to carry input power current. Just saying, to double check we are all fully in agreement on how it should work.
Yes that's what I was getting at and what he needs to confirm.
Otherwise it sound like a ground loop to the external gear (amp?).
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