This is actualy part of my question. What is the real difference. What are the benefits of two trafos with two diodes over one trafo and full wave bridge?
Is a morning and more power to dig fo an answer :-D
Rectifier - Wikipedia, the free encyclopedia
Full Wave Rectifier and Bridge Rectifier Theory
http://www.diyaudio.com/forums/parts/49327-full-wave-vs-full-wave-bridge-rectifier-4.html
After reading these and some more, there was no clear statement of superiority of one over other. Only difference found was more voltage loss in full wave bridge as there are two more diodes.
Can anyone please let us understand where is the advantage of two diodes full wave rectifier in this particular application (DAC)?
I can do both options in my psu, just want to be aware of what and why I'm actually doing.
Thank in advance
I'm curious myself! It's individual to each Transformer, but this Cheapmodo circuit means you just join a 9v battery, this circuit and a scope to your transformer secondary, dial in the values you need, then swap out for individual components and join the secondaries back to your equipment. Sounds easy enough, time will tell.....
Interesting on the common mode vs serial.. I don't have enough voltage headroom with my 12v tx to run the second choke in series, but I could easily bridge between the dirty star and clean star in my circuit to bypass the choke in the gnd line for a comparison test.
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Difference in voltage is about 0.5V, between the two options, depending on diode spec. Try for your selve, see what you like best. I like two diodes better.
I thought I'd tried this in the past and got a bigger difference. But when I made the swap from common to series last week, the voltage at the dac didn't change...
G600@
I removed the cap between the rectifiers and the first choke. Volt at output is now only 11vdc, but no problem at all. My first impression is that the sound is better than with the cap in place. It seems that you are right.
Need to get a bleeder with som more ohm to hit the 12v target. Or is it ok as it is with 11v ? Dddac perform great with 11v, but maybe even better with 12v ?
Thanks Doede! Works perfectly!
Thanks stijn001, yes the difference in mine is 0.4V on the first 2min and then stabilised on 0.25 -0.3V, really not much. I'm in phase of ordering mainboard and dac boards now therefore I can't listen to the difference, but after the lecture that dwjame has posted I'm getting more clear idea of the process of creation
and importance of small details that at first glance seem not important at all.Now my entire universal PSU for DAC and HTPC in one is up and running, case for it ordered. Next step is DAC itself with stepped attenuator.
I'm considering encapsulation of my chokes with epoxied resin to lower, if not eliminate these vibration. I read somewhere that this process has has some negative influence on the current, kind a slows it down (due to pressure from dried and shrinked resin).
I actually ordered the main trafo encapsulated. But it is big and appreciated by many. So I risked and got one. In fact I can hear trafos from my amp, but this one is 100% silent and no vibes.
I know it might be a different story with small transformers like these Lundahl chokes. Do you guys have had some experience with encapsulated transformers vs not encapsulated? Do you maybe have any advice in that matter please? Is it worth doing at all?
11v should be fine. I have just under 11v now. If you're using TentLabs shunt regs, Guido told me they need 2v headroom, so as long as you have 10v at the 8v reg input, all is well
As I understand, using a correctly sized snubber across the transformer secondaries can help reduce ringing and emi from the transformer. That's my plan anyway..
11v should be fine. I have just under 11v now. If you're using TentLabs shunt regs, Guido told me they need 2v headroom, so as long as you have 10v at the 8v reg input, all is well
Thx James. I do not have the Tent labs, but everything seems to work out fine with only 11v.
Today i will give the WaveIo a choke psu. Have two Hammond chokes laying around, and with some Mundorf AgLytic 3300caps and a bleeder I hope to be able to put together 5v. Anybody know how many % +/- 5v, is safe for WaveIo? I know it's always safer to be a bit lower, but I want the best possible performance.
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The two diode full wave rectifier used with split tranny ac supply should sonically the same as the 4 diode full wave bridge on a level playing field basis ie no diodes to earth i.e provided the bridge is fully floating i.e not taken to ground on one side. Two diode is easier to implement. With CLCLC etc you should be ok on one transformer
Just finished choke input psu for the WaveIo usb. I measured 4.8v and connected the dac to my system and everything seems fine. BUT,,,,,Foobar didn't find WaveIo ??? After some thinking I decided to put a small cap after the rectifiers to get closer to 5vdc, and got very close ( 4.997vdc ).
Started Foobar again, and there WaveIo showed up. So you can't go much under 5vdc on the WaveIo before it dissappear from the PC.
Started Foobar again, and there WaveIo showed up. So you can't go much under 5vdc on the WaveIo before it dissappear from the PC.
random thoughts
Hello,
So we believe him when he says that 2 diodes are better than 4 But he also states that differences between diodes are just minimal.
I guess we just have to try ourselves. lol
BUT i will be using a lundahl choke. I will use the ll2733 in common mode and choke input and i expect a big effect.
The writer of this webpage suggest mounting the diodes close to the first cap so we also should put them close to the choke input if we decide to go for that solution. I think in general it is good to keep the secondary windings of the power transformer close to the first filter. The orientation of the lundahl chokes towards the R core power transformer can be determined by using a voltmeter. I did use an anode choke made by lundahl which has the same structure as a power supply choke but a big number of Henries so more sensitive. I did find the paper with the results but the drawings are not clear to me so i have to do it again. Largest voltage measured was 0.133 volt lowest voltage was 0.006 volts.
Because the current drawn by a multiple dac board and some shunts can be high i think positioning the chokes in the right way could make a difference.
Lundahl people did tell me the biggest issue will be the influence of the power transformer on the output transformer.
Sincere greetings, edward
Hello,
So we believe him when he says that 2 diodes are better than 4 But he also states that differences between diodes are just minimal.
I guess we just have to try ourselves. lol
BUT i will be using a lundahl choke. I will use the ll2733 in common mode and choke input and i expect a big effect.
The writer of this webpage suggest mounting the diodes close to the first cap so we also should put them close to the choke input if we decide to go for that solution. I think in general it is good to keep the secondary windings of the power transformer close to the first filter. The orientation of the lundahl chokes towards the R core power transformer can be determined by using a voltmeter. I did use an anode choke made by lundahl which has the same structure as a power supply choke but a big number of Henries so more sensitive. I did find the paper with the results but the drawings are not clear to me so i have to do it again. Largest voltage measured was 0.133 volt lowest voltage was 0.006 volts.
Because the current drawn by a multiple dac board and some shunts can be high i think positioning the chokes in the right way could make a difference.
Lundahl people did tell me the biggest issue will be the influence of the power transformer on the output transformer.
Sincere greetings, edward
Thanks dwjames! yes I found that this will in fact help a lot with emi. But still there can be some vibrations and magnetic fields emitted from the transformer, I believe there are no big vibrations from Lundahls, but electro magnetic field is there. After rethinking the case I think that making some screening shield boxes should do it.
Do you think that can help in case of Lundahls?
Do you have some reference links to how to count snubber values?
Thanks boldname and eduard! Yes I do experiments and I will test it on fully built system when ready to be sure i'm taking right decision with my ears
. I actually have my power trafo fully encapsulated with good anti magnetic inox shield. Should that make positioning of Lundahls easier? As you see, I'm planning to screen also Lundahls. This should (in my opinion) minimize mutual interferences, shouldn't? I'll do positioning of diodes physically as close as possible. Apart from three 2200uF caps before the first choke, should I place also one small to reduce noise from Shottkys? Or is ok with only these three?http://www.divshare.com/download/26815495-1db
An externally hosted image should be here but it was not working when we last tested it.
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Hello,
I think if you look at most commercial design with a seperate power supply they will have the power supply with the rectifier the first cap ( sometimes a choke) in one chassis and the last cap close to the circuit in the other chassis.
I think using R core power transformer (s) and lundahl chokes and a bit of logic with chassis layout will give the best results.
If only 2 chassis is possible i would put the transformer, diodes, common mode choke ( choke input!) and the first cap close together in one chassis. The second choke and the final cap close to the circuit.
If you connect the choke in common mode you will have to connect the ground at the '' exit '' of the choke so if the last choke before the circuit is also connected in common mode the ground connection can be short and maybe it will give better filtering than a 60 centimeters cable from one chassis to the circuit??
Sincere greetings, Edward
lundahl positioning.
Hello,
Mounting the chokes in a vertical direction with the 4 mounting holes facing the power transformer will give the lowest interference with my R core power transformer. When using a toriodal transformer one might get less interference turning it around its axe.
Lundahl did tell me the coupling between chokes and power transformer usually isnt a problem. You could screen then with a steel ( not Stainless steel) cover but they dont think it is necessary.
Why dont you go for choke input ( maybe you will need another transformer lol) The information i did read so far usually says that R core is the way to go.
Sincere greetings, edward
Hello,
Mounting the chokes in a vertical direction with the 4 mounting holes facing the power transformer will give the lowest interference with my R core power transformer. When using a toriodal transformer one might get less interference turning it around its axe.
Lundahl did tell me the coupling between chokes and power transformer usually isnt a problem. You could screen then with a steel ( not Stainless steel) cover but they dont think it is necessary.
Why dont you go for choke input ( maybe you will need another transformer lol) The information i did read so far usually says that R core is the way to go.
Sincere greetings, edward
Which would be the best shop in Europe to order such a transformer?
Update
I guess I can answer this question
http://www.selectronic.fr/transformateur-r-core-300va-avec-etrier-5.html
http://www.shilchargroup.com/electronics-telecom/r-core.html?pg=pr&sid=rc
Update
I guess I can answer this question
http://www.selectronic.fr/transformateur-r-core-300va-avec-etrier-5.html
http://www.shilchargroup.com/electronics-telecom/r-core.html?pg=pr&sid=rc
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just an in between comment.... This post is mostly about tweaking the DAC and I heard some remarks like "will the dddac only sound good if you do all this significant tweaking?"
If I say it does, it might sound biased, so I was happy to receive this feedback from a very happy DIY who built the stock version and was obviously very content... Of course that does not mean tweaking cannot bring another notch of sound quality and for all fun....
Quote:
Doede,
I finished my single-board DAC and two PSUs today, with Cinemag output transformers. I plugged it in to my Sqeezebox, configured everything, and let it rip on my SET 300b rig (DIY).
Holy smokes, my mouth hit the floor three hours ago and has not returned to my face! I have been listening all afternoon, hearing stuff I never heard before. The things I notice over my (cheap) tube DAC I was using are much tighter bass, more detail, wide staging, and more presence. Coupled with a very non-fatiguing, natural sound. It is also dead quiet on 98db/speakers.
Thanks for putting such an excellent DAC in the hands of the DIY crowd!
Adam
Minneapolis, MN USA
If I say it does, it might sound biased, so I was happy to receive this feedback from a very happy DIY who built the stock version and was obviously very content... Of course that does not mean tweaking cannot bring another notch of sound quality and for all fun....
Quote:
Doede,
I finished my single-board DAC and two PSUs today, with Cinemag output transformers. I plugged it in to my Sqeezebox, configured everything, and let it rip on my SET 300b rig (DIY).
Holy smokes, my mouth hit the floor three hours ago and has not returned to my face! I have been listening all afternoon, hearing stuff I never heard before. The things I notice over my (cheap) tube DAC I was using are much tighter bass, more detail, wide staging, and more presence. Coupled with a very non-fatiguing, natural sound. It is also dead quiet on 98db/speakers.
Thanks for putting such an excellent DAC in the hands of the DIY crowd!
Adam
Minneapolis, MN USA