@phase,
Across what are you suggesting the X2 caps? 240 VAC mains or stepped down 9-12 VAC?
@eljoAntonyn,
Buy KEMET R474N31005001K Film Capacitor, 0.1 �F, X2, R47 X2 Series, 440 V, PP (Polypropylene) in India India – Tanotis
Across what are you suggesting the X2 caps? 240 VAC mains or stepped down 9-12 VAC?
@eljoAntonyn,
Buy KEMET R474N31005001K Film Capacitor, 0.1 �F, X2, R47 X2 Series, 440 V, PP (Polypropylene) in India India – Tanotis
They also keep a lot of stuff in stock. The cost on the site is inclusive of duties and tax.
Forget the snubber across the diodes for now unless you have a scope to determine the correct value of R & C for the snubber.
Better still, implement a snubber across the secondary of the transformer [100nF cap + 1k pot in series]. Keep adjusting the value of the pot and check if you hear a difference.
And implement what Phase suggested of caps across power pins of the op-amp and the X2 cap across VAC.
And try the op-amp's I suggested especially the NE5534AP.
Let us know how it goes.
Forget the snubber across the diodes for now unless you have a scope to determine the correct value of R & C for the snubber.
Better still, implement a snubber across the secondary of the transformer [100nF cap + 1k pot in series]. Keep adjusting the value of the pot and check if you hear a difference.
And implement what Phase suggested of caps across power pins of the op-amp and the X2 cap across VAC.
And try the op-amp's I suggested especially the NE5534AP.
Let us know how it goes.
Do you have an oscilloscope to check for ringing? If you look at the Quasimodo jig for selecting snubber component values, doing it right can be involved.
A lot depends on the transformer. Only using a capacitor and no snubber resistor can at least be expected to lower the frequency of ringing, which might be an improvement. What make ringing stop is resistance which dissipates energy into heat.
If no scope, no distortion analyzer, no other power supplies that can substituted for test that are know to be good, etc., the only way to be pretty sure you aren't going to have audible transformer ringing problems would be use really good rectifiers. Not cheap though, agreed on that. Neither are scopes, distortion analyzers, etc. Life can be complicated, choices have to be made, maybe more chances taken that would be nice.
Still, and we keep coming back to this, it is a low cost dac. If you do end up with expensive rectifiers consider keeping them for the next dac when this dac's time is up. If you keep the rectifiers you have now, then that may be okay too. Maybe the next dac down the road can be better in multiple ways.
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@Mark4
I do not have an oscilloscope and I'm not good with electronics design. SO, designing a snubber circuit would be a herculean task for me. I'm a Mechanical Design Engineer. I can design a good case and get it lasercut, thats the only thing my professional knowledge empowers me to do for this low cost DAC.
Yes, I plan on keeping the soft recovery rectifier for other projects along with the AD811 opamps. Review: Wolfson WM8740 USB DAC from China - Music Server Tips
This link points to a review of the said board. Also check the comments at the bottom. Most of the buyers seems to like it. According to the comments, the NE5534 sounds the best albeit being a bit 'thin'. One of the commenters found the OPA134 to be 'musical' and better suited to his tastes.
Musical means mid prominent sound, right ? SO, for this, the ideal combination is NE5534 2 nos or the OPA134 2 nos or the OPA2134.
@Keith
Oh, didn't know they keep some in stock ! Thanks for the headsup. I'll get the NE5534 for sure.
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Would the 0.33uF cap work or I need an exact 0.1uF cap ?
Also, the 100uF cap mentioned is polypropelene, right ?
I do not have an oscilloscope and I'm not good with electronics design. SO, designing a snubber circuit would be a herculean task for me. I'm a Mechanical Design Engineer. I can design a good case and get it lasercut, thats the only thing my professional knowledge empowers me to do for this low cost DAC.
Yes, I plan on keeping the soft recovery rectifier for other projects along with the AD811 opamps. Review: Wolfson WM8740 USB DAC from China - Music Server Tips
This link points to a review of the said board. Also check the comments at the bottom. Most of the buyers seems to like it. According to the comments, the NE5534 sounds the best albeit being a bit 'thin'. One of the commenters found the OPA134 to be 'musical' and better suited to his tastes.
Musical means mid prominent sound, right ? SO, for this, the ideal combination is NE5534 2 nos or the OPA134 2 nos or the OPA2134.
@Keith
Oh, didn't know they keep some in stock ! Thanks for the headsup. I'll get the NE5534 for sure.
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Would the 0.33uF cap work or I need an exact 0.1uF cap ?
Also, the 100uF cap mentioned is polypropelene, right ?
Ah! Then, maybe you should design a nice [inexpensive!] case for this DAC after all your mods are done. I have the same DAC and it deserves a nice case - so when you design and build one for your DAC, build 2, I'll buy one off you!
@KEITH
Cool ! Why not ! But, its not gonna be cheap though. Can't compete with the Chinese ! If you read the article I posted, a guy mentioned a case (Aluminium) specific to this DAC board. I'm guessing around 22USD, shipped ! So, what do you think ?
Anyway, what mods have you done to the DAC board ? Can you detail them here ?
Cool ! Why not ! But, its not gonna be cheap though. Can't compete with the Chinese ! If you read the article I posted, a guy mentioned a case (Aluminium) specific to this DAC board. I'm guessing around 22USD, shipped ! So, what do you think ?
Anyway, what mods have you done to the DAC board ? Can you detail them here ?
It's my backup DAC so apart from changing the op-amp, none! But, based on the effectiveness of your mods, maybe I'll implement some that are detailed here - so I'm piggybacking on your experiences!
@Keith
Read the review of our DAC from the link I posted. Then read the comments !
I'm checking out Kitsnspares but the shipping is very high even though the have almost all kind of electronics stuff with them. The AD811 I purchased yesterday for like Rs 300 is costing round 750 here with out considering taxes and shipping ! I still can't seem to trust tanotis.com !
Read the review of our DAC from the link I posted. Then read the comments !I'm checking out Kitsnspares but the shipping is very high even though the have almost all kind of electronics stuff with them. The AD811 I purchased yesterday for like Rs 300 is costing round 750 here with out considering taxes and shipping ! I still can't seem to trust tanotis.com !
Hi Guys !
I'm starting to receive the ordered parts. First to arrive are the AD811 opamps and the soft recovery diodes.
Gonna replace the Schottky diode on the board with the soft recovery diode but its gonna be very tight ! That big u4700F electrolytic cap need to be .....re-arranged, it seems.
I'm gonna keep the AD811 in the closet as I don't know if it would work with my DAC.
By the way, I just did a small calculation on money spent ordering these parts. I have now exceeded the amount I paid for the DAC board lol
I hate DIY
I'm starting to receive the ordered parts. First to arrive are the AD811 opamps and the soft recovery diodes.
Gonna replace the Schottky diode on the board with the soft recovery diode but its gonna be very tight ! That big u4700F electrolytic cap need to be .....re-arranged, it seems.
I'm gonna keep the AD811 in the closet as I don't know if it would work with my DAC.
By the way, I just did a small calculation on money spent ordering these parts. I have now exceeded the amount I paid for the DAC board lol
I hate DIY
SO, I soldered the rectifiers in with some difficulty as those were BIG ! Had to bend the leads of the second one to fit in the holes and yeah, lots of sandpaper action !
Then, I turned on the DAC and ......thankfully nothing happened like amp exploding, main elcb tripping, power supply caps bursting into flames etc.
BUT THE THE the sound...its like...I don't know how to describe it. I was playing the "The National Anthem - Live in France" of Radiohead and I could even hear the chickens in their pens right next to the concert venue!
The sound stage is pure 4D like I'm sitting inside the stage where the band was performing
What a change !!!
lol no
I could not hear any change at all. May be a bit better bass ?
Might be my mind playing tricks
Then, I turned on the DAC and ......thankfully nothing happened like amp exploding, main elcb tripping, power supply caps bursting into flames etc.
BUT THE THE the sound...its like...I don't know how to describe it. I was playing the "The National Anthem - Live in France" of Radiohead and I could even hear the chickens in their pens right next to the concert venue!
The sound stage is pure 4D like I'm sitting inside the stage where the band was performing
What a change !!!
lol no
I could not hear any change at all. May be a bit better bass ?
Might be my mind playing tricks
It just means that rectifiers probably weren't your biggest problem with sound quality. If you get your dac very clean then you very well might hear effects from transformer ringing and need to do something to fix it.
Or, you might go about doing things a little out of order by fixing things first that aren't really the biggest problems, simply because you find them doable now. People often do are things like swapping caps and opamps because that is what they know how to do, not because they know exactly what is causing all the limitations of sound quality.
Also, to some extent as a hobbyist you may have to experiment to learn and to find out what needs fixing the most. If you read about my journey modding ES9038Q2M dac boards you can see there has been a lot of work involved in trying many different things. It wasn't until rather recently that I found some transformer noise/ringing problems I had to do something about, but I didn't know when it was going to happen, or if I would ever need to. In that case it was the 3rd transformer I tried that worked best and solved the problem.
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@Markw4
There is some change in sound but I'm not 100% sure whether its the "expectation bias" or not.
Yes, there may be lots of stuff going with the DAC like fake components, badly designed circuits, wrong values of components used etc. Now, I need to find out. I'll start with the PCM2704 and the WM8740 datasheet.
Let me see if I can spot any error !
There is some change in sound but I'm not 100% sure whether its the "expectation bias" or not.
Yes, there may be lots of stuff going with the DAC like fake components, badly designed circuits, wrong values of components used etc. Now, I need to find out. I'll start with the PCM2704 and the WM8740 datasheet.
Let me see if I can spot any error !
Well, how do you think it sounds different? If a difference can be explained by Fletcher and Munsen, then very likely not real. Even less than .1dB volume difference can make something sound better or worse, although it may not be perceived as louder or softer exactly. So, I always recommend to adjust the volume control and listen for things that don't change with small volume level changes. The little details of cymbal sounds at different frequencies in a piece of well recorded music can be very revealing/enlightening.
Well, I used the same songs with the same volume (volume control is with my integrated amp) before and after.
Like I said its like bass hits a tiny bit harder ? I don't know !
I'll do a listening comparison vs my iPad (my amp have multiple inputs) after getting the AC filtering capacitor fitted to the transformer primary.
Like I said its like bass hits a tiny bit harder ? I don't know !
I'll do a listening comparison vs my iPad (my amp have multiple inputs) after getting the AC filtering capacitor fitted to the transformer primary.
Same songs are good, so long as they are well recorded and not too distorted themselves. Leaving the volume the same is not good, you need to adjust the volume while you listen to see what effect it has. Since it can easily change bass perception relative to other frequencies, it can be hard to be sure about bass changes. Helps to have a reference dac or sound source to compare with before and after the change. Is the bass different relative to the reference source (while adjusting the the volume of each one to see how it affects the sound) that you can A/B listen to now (and not having to rely on your memory of the bass from before)? The more accurate the reference source is, the more useful it probably is to have around to use kind of like a type of test instrument. I understand not everybody can do that, especially when working on a first project, just saying it can be helpful if you can manage to arrange for it.
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