Hello,
My present cable has BNC so i will put bnc on the mainboard. You have any idea if the new dac board suitable for the Tent shunt will also require a new motherboard. I might start with one board with shunts and then when a new board get available go for four with shunts. But almost sure i will go for the big output transformer. Ther one with some gain but i think that one requires more dac boards.
After summer holidays i will have a meeting with Supersurfer to compare my R-core 300va supply with probably a 400mH as choke input input common mode and a smaller 160mH as regular or also common mode with his power supply.
He did make an extra rc network for a lower tension needed at the board. What is the current involved there( also depending on the shunts?)
Sincere greetings, edward
My present cable has BNC so i will put bnc on the mainboard. You have any idea if the new dac board suitable for the Tent shunt will also require a new motherboard. I might start with one board with shunts and then when a new board get available go for four with shunts. But almost sure i will go for the big output transformer. Ther one with some gain but i think that one requires more dac boards.
After summer holidays i will have a meeting with Supersurfer to compare my R-core 300va supply with probably a 400mH as choke input input common mode and a smaller 160mH as regular or also common mode with his power supply.
He did make an extra rc network for a lower tension needed at the board. What is the current involved there( also depending on the shunts?)
Sincere greetings, edward
Just to keep expectations on a realistic level... there won't be a board for the shunts this year. probably next year. But when it comes, it will be fully compatible, electrically AND mechanically with the old DACs !
Hi Edward,
I have not measured yet, but I am using 30mA 3.3v shunts and in total 8 shunts will yield around 250mA for the digital stage.
Regards,
I have not measured yet, but I am using 30mA 3.3v shunts and in total 8 shunts will yield around 250mA for the digital stage.
Regards,
Hello,
I think i will probably gop for one dac board with shunts and when the new board arrive next year i might go for 4 new boards with shunts but i also want the big output transformer. But i think they need 4 boards for lower impedance output.
Anyway 250ma will be a bih choke but dont need much inductance because there is already two in front. Just like a kind of extra decoupling.
In the past i did meet people who did tell me it is better to use the connection at the choke as start to the next choke and not go from the cap to the choke. I never try but they did.
Sincere greetings, edward
The R core choke 2*20mH 2.5 A that i did buy did get even more cheaper 20.03 euro for 2 kilogrammes of metal. Not bad
I think i will probably gop for one dac board with shunts and when the new board arrive next year i might go for 4 new boards with shunts but i also want the big output transformer. But i think they need 4 boards for lower impedance output.
Anyway 250ma will be a bih choke but dont need much inductance because there is already two in front. Just like a kind of extra decoupling.
In the past i did meet people who did tell me it is better to use the connection at the choke as start to the next choke and not go from the cap to the choke. I never try but they did.
Sincere greetings, edward
The R core choke 2*20mH 2.5 A that i did buy did get even more cheaper 20.03 euro for 2 kilogrammes of metal. Not bad
Self de filtrage 50Hz - 2X20mH - 2.5A - Inductances
Hello,
As you can see from france. Mister Chanh from Perth is probably gonna order them too.
They have about 28 in stock if i remember correctly. When i did order one they were a few euro more but they look nice. I fid check for him two transformers 300va and 2 chokes would be around 45 euro for postage to australia.
Sincere greetings, edward
Hello,
As you can see from france. Mister Chanh from Perth is probably gonna order them too.
They have about 28 in stock if i remember correctly. When i did order one they were a few euro more but they look nice. I fid check for him two transformers 300va and 2 chokes would be around 45 euro for postage to australia.
Sincere greetings, edward
Hi Doede,
Does it mean, the new/revise board has build-in Shunt regs? Or simply has the flexibility to install third party's shunt regs?
Regards,
Chanh
@nige2000:
I currently use Rubycon ZLH 270 uF for the Vcom capacitors and this works very well, however, since they in my current PCB layout are placed below the PCB it's not that easy to replace them in a way that allows for A/B listening ... (I will be using Rubycon ZLs in my final version). I've also tried Nichicon e-le capacitors in this place (820 uF Solid Polymer capacitor, ultra-low ESR) but maybe because of these capacitors' high leakage current (~1 mA) or because I used 4VDC types 🙂-( what I had) it didn't work out electrically (to my memory it was not the same current output in both channels).
About SMD caps in this place besides the Solid polymer types I'd personally hesitate to use other SMD capacitor types (due to distortion/sound) but they probably could be used from an electrical point of view.
Cheers,
Jesper
I currently use Rubycon ZLH 270 uF for the Vcom capacitors and this works very well, however, since they in my current PCB layout are placed below the PCB it's not that easy to replace them in a way that allows for A/B listening ... (I will be using Rubycon ZLs in my final version). I've also tried Nichicon e-le capacitors in this place (820 uF Solid Polymer capacitor, ultra-low ESR) but maybe because of these capacitors' high leakage current (~1 mA) or because I used 4VDC types 🙂-( what I had) it didn't work out electrically (to my memory it was not the same current output in both channels).
About SMD caps in this place besides the Solid polymer types I'd personally hesitate to use other SMD capacitor types (due to distortion/sound) but they probably could be used from an electrical point of view.
Cheers,
Jesper
Well I'm happy to report 2 big breakthroughs here today! 🙂
First is I switched my new power supply back to choke input, only this time I wired in the first choke correctly in series as per the datasheet, then the second choke I wired in common mode rejection mode with the v+ through one winding and the gnd through the other. I currently have 2 x 2,200uf Panasonic FM after each choke and a 57R bleeder after the first choke. With a 2 x 12v transformer, I get 12.3v into the first choke and 11.24v after the second choke. I had already bridged R2/R4 and L3/L3 on the dac board, but I had to also reduce R1/R3 down to 6ohm instead of 10ohm to give me 10.3v at the 8v regs. Well, wow! I really like how that sounds. Very lucid and up front with good body and great detail. Very nice indeed.
But the background interference noise was still really bugging me, so after trying going around the house turning almost every single other electrical thing off and still having the noise, I go back to the start again. To cut a long story short, that horrible noise was almost entirely caused by the ethernet cable into the raspberry pi transmitting noise into the dac over the I2S cables... I had ruled out the sound coming from the pi fairly early on by unplugging the power from it and noticing no difference, but I hadn't thought to pull the ethernet cableand recently I haven't been running with the I2S isolator 🙄 The ethernet connection in both places I've been testing the DAC is plugged into a powerline adapter attached to the mains. So I still think the noise comes from horrible dirty mains, but it's being transmitted direct into the dac via the ethernet cable 🙄 Well, that's an easy problem to fix, so I've swapped back to using wifi and wow! The noise has almost entirely dropped off. It's now 5-10% of what it was before and the details are really shining through now. Very happy indeed 😀 With this new power supply and the shunt regs sat so close to the DAC chip where I have them mounted now, it's certainly the best I've ever heard it.
Happy days. loving the music 😎 thanks again to Doede for providing the difficult bits to make this all happen and to you guys here for the inspiration and guidance 🙂
Sorry that I only read about your noise problems after the fix because I read recently about the ethernet noise here...
Tracking down noise sources on a Raspberry Pi | Crazy Audio
May be of interest to you. They suggest using wireless, but also suggest trying an unshielded patch cable if you are not using wireless.
actually I am still considering both options.... this will allow for further individualizing of the dac
for those in europe probably
Hello ,
Today did get my double coil r core choke. 2 times 20mH so for choke input you will need a big bleeder and/or some shunts. If you use it common mode it will act like a 40mH choke for calculating the necessary current to make it work as a choke input. To be sure you could put two of them in series.
I will probably go for the ll2733 and a ll1694 from lundahl.
This 20mH is rated for 2.5 A could be nice for a power amp too i guess
Sincere greetings, edward
Hello ,
Today did get my double coil r core choke. 2 times 20mH so for choke input you will need a big bleeder and/or some shunts. If you use it common mode it will act like a 40mH choke for calculating the necessary current to make it work as a choke input. To be sure you could put two of them in series.
I will probably go for the ll2733 and a ll1694 from lundahl.
This 20mH is rated for 2.5 A could be nice for a power amp too i guess
Sincere greetings, edward
Attachments
I made a discovery today about how I have wired the output from my DDDAC which I wanted to share.
For a long time now, I have wired direct from NEG to my RCA outer and from POS to the RCA inner. No caps, no transformers. I know a few people are running like this and reporting that it sounds very nice and an improvement over using POS with a cap and COMMON. I found this too.
But someone who was trying this solution (Hi Nige 🙂) mentioned that their sound from each channel sounded much nicer when only 1 RCA was plugged into their amp and with both plugged in, it lost some of the detail and sounded flat. I never noticed this because I never had only 1 channel at a time plugged in, always both.
The theory was that with this method, the NEGs will be joined and must share the music signal across the channels, so half of each channel's signal which reaches the speakers is made up of a MONO/mix of both channels.
So I made a test file:
click and tone test file mp3
The left track is a click track, right track is a sine wave tone.
With only 1 RCA plugged in at a time, the left channel just gets the tone, the right channel just gets the click. But with them both plugged in and therefore the neg connections bridged together at the preamp, each channel gets it's own signal, plus a quieter (I guess 1/4 volume?) copy of the other channel as well.
So it seems that unless you have an amp solution with totally separate channels where the signal GND is not joined, this will always be the case and there will always be a Mono/mixed element to each channel when wiring like this.
I have some Cinemags here now. I'll try them later and compare....
For a long time now, I have wired direct from NEG to my RCA outer and from POS to the RCA inner. No caps, no transformers. I know a few people are running like this and reporting that it sounds very nice and an improvement over using POS with a cap and COMMON. I found this too.
But someone who was trying this solution (Hi Nige 🙂) mentioned that their sound from each channel sounded much nicer when only 1 RCA was plugged into their amp and with both plugged in, it lost some of the detail and sounded flat. I never noticed this because I never had only 1 channel at a time plugged in, always both.
The theory was that with this method, the NEGs will be joined and must share the music signal across the channels, so half of each channel's signal which reaches the speakers is made up of a MONO/mix of both channels.
So I made a test file:
click and tone test file mp3
The left track is a click track, right track is a sine wave tone.
With only 1 RCA plugged in at a time, the left channel just gets the tone, the right channel just gets the click. But with them both plugged in and therefore the neg connections bridged together at the preamp, each channel gets it's own signal, plus a quieter (I guess 1/4 volume?) copy of the other channel as well.
So it seems that unless you have an amp solution with totally separate channels where the signal GND is not joined, this will always be the case and there will always be a Mono/mixed element to each channel when wiring like this.
I have some Cinemags here now. I'll try them later and compare....
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ya i think that is exactly the situation with this
didnt want to post about it here till someone could confirm/recreate what i was hearing
aka didn't wanna look like a moron if i was doing something wrong
think it leaves us with dual mono and/or separate gnds only
id also question how the amps and speakers handle the neg signal?
surely weren't designed to receive it?
thnx Jesper
interesting stuff
ordered a bit of a selection to try will report back
Hi nige2000,
... could be interesting to hear about your results, however, I hope to finish my DAC in just a week or so so I won't have time to get your results ...
Anyway, I did some measurements with my oscilloscope on the Vcom terminals and the noise level here was quite low compared with what was visible on the VCC terminals (~1000 uF low ESR filtering). As it is, my oscilloscope was unable to indicate any noise/signal on the Vcom pins (with ~ 330 uF low ESR filtering). Just FYI - my guess is that listening could be a way to find out whether there's anything to be gained in using good &/or larger size capacitors here.
Cheers from Denmark,
Jesper
... could be interesting to hear about your results, however, I hope to finish my DAC in just a week or so so I won't have time to get your results ...
Anyway, I did some measurements with my oscilloscope on the Vcom terminals and the noise level here was quite low compared with what was visible on the VCC terminals (~1000 uF low ESR filtering). As it is, my oscilloscope was unable to indicate any noise/signal on the Vcom pins (with ~ 330 uF low ESR filtering). Just FYI - my guess is that listening could be a way to find out whether there's anything to be gained in using good &/or larger size capacitors here.
Cheers from Denmark,
Jesper
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So I swapped for Cinemags at my output now. I had ordered them ages ago, but not fitted as I was happy with using pos and neg with no caps and intended to sell them.
For reference, I used 13.6k (2 x 6.8k)Ohm load resistors across the rca, which when combined with the 50kohm from my amp give approx the 10k load which puts the Cinemags in their sweet spot.
As always, just a trial fit. I need to tidy and shorten the wires.
Using the same test mp3 file I confirmed that I have proper separation of the left and right channels now and all is good there.
Sound-wise, my stereo imaging and particularly the width of the sound stage is greatly improved. Not surprising really when you consider the effect of partially merging the channels like I was....
Anyway, I seem to be saying this a lot lately, but I'm really happy, it's the best I've ever heard it sound. Excellent 🙂
For reference, I used 13.6k (2 x 6.8k)Ohm load resistors across the rca, which when combined with the 50kohm from my amp give approx the 10k load which puts the Cinemags in their sweet spot.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
As always, just a trial fit. I need to tidy and shorten the wires.
Using the same test mp3 file I confirmed that I have proper separation of the left and right channels now and all is good there.
Sound-wise, my stereo imaging and particularly the width of the sound stage is greatly improved. Not surprising really when you consider the effect of partially merging the channels like I was....
Anyway, I seem to be saying this a lot lately, but I'm really happy, it's the best I've ever heard it sound. Excellent 🙂
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Hello James,
When you begin reducing wire length. You could also go for another type of transformer. I did allready order this one.
Transformateur R-CORE à fixation sur châssis 300VA - 2 x 15V - R-CORE pour châssis
Right now it is out of stock but they have 120va models too that will cost about 40euro. If you need 12 volts ac you can also go for 2 times 6 in series. There is promotion it is about 66 euros for a 300va type,
Sincere greetings, edward
When you begin reducing wire length. You could also go for another type of transformer. I did allready order this one.
Transformateur R-CORE à fixation sur châssis 300VA - 2 x 15V - R-CORE pour châssis
Right now it is out of stock but they have 120va models too that will cost about 40euro. If you need 12 volts ac you can also go for 2 times 6 in series. There is promotion it is about 66 euros for a 300va type,
Sincere greetings, edward
Hi James,
Your inputs and so others are invaluable! Without them will potentially be a costly exercise for many of us. I personally found these posts are very educational which often mitigate many pitfalls.
Again, thank you and please keep them coming!
My 47 Shunts order is finally placed. However, I requested to have 8.3V shunts instead of 8V because I recalled some here previously posted that they found at 8.6V yields the best SQ. I also followed up with DDDAC website where this was also concur at 8.5V. So I choose 8.3V to be on the safe side.
I might not go up to 11-DAC boards with Shunts so if anyone in Australia is needing a set of four(2x3.3 and 2x8.3) let me know? I might have 3 sets spare if am happy with the current 8-Decks and shunt regs.
I did a preliminary unregulated ps, but failed in correctly wired up the Schottky rectifiers. If any one here can come to the rescue with photos are appreciated. Apparently I failed despited I followed the symbol illustration of full wave rectifiers on the net, Wikipedia... LoLz!
Best,
Chanh
Your inputs and so others are invaluable! Without them will potentially be a costly exercise for many of us. I personally found these posts are very educational which often mitigate many pitfalls.
Again, thank you and please keep them coming!
My 47 Shunts order is finally placed. However, I requested to have 8.3V shunts instead of 8V because I recalled some here previously posted that they found at 8.6V yields the best SQ. I also followed up with DDDAC website where this was also concur at 8.5V. So I choose 8.3V to be on the safe side.
I might not go up to 11-DAC boards with Shunts so if anyone in Australia is needing a set of four(2x3.3 and 2x8.3) let me know? I might have 3 sets spare if am happy with the current 8-Decks and shunt regs.
I did a preliminary unregulated ps, but failed in correctly wired up the Schottky rectifiers. If any one here can come to the rescue with photos are appreciated. Apparently I failed despited I followed the symbol illustration of full wave rectifiers on the net, Wikipedia... LoLz!
Best,
Chanh
I finally able to get the 11 decks up and running. So far I heard the sound more refined again. I dare not imagining once these were fitted with Tentlabs Shunt regs!?!? Happy days are coming. Will keep you guys posted.
My priorities are to get the unregulated chokes input ps up and running, BBB with Cape i2s direct to DAC and following the Shunts regs mod, finally get all in a nice housing with LCD display.
Here are few quick snap-shots from my phone camera;
My priorities are to get the unregulated chokes input ps up and running, BBB with Cape i2s direct to DAC and following the Shunts regs mod, finally get all in a nice housing with LCD display.
Here are few quick snap-shots from my phone camera;