bootstrap cap
Bruno,
The bootstrap cap sees only low voltage right? Possibility an Oscon would work very well here. See any problems with going to something with this low of ESR? I know, not a trivial question as peak currents could be much higher.
Roger
Bruno,
The bootstrap cap sees only low voltage right? Possibility an Oscon would work very well here. See any problems with going to something with this low of ESR? I know, not a trivial question as peak currents could be much higher.
Roger
Re: bootstrap cap
There is nothing against oscon here. 220u/16V should do nicely. This part of the circuit is not extremely picky about esr, in neither direction.sx881663 said:
Julien,
Which one is the low voltage decoupling caps?
And when you remove the C23, c24, do you just short them after the removal?
Which one is the low voltage decoupling caps?
And when you remove the C23, c24, do you just short them after the removal?
ackcheng said:
I've attached a photo showing the low voltage decoupling caps in my module. I don't have it in view to give you the capacitor numbers in the PCB.
The input caps were replaced with a small piece of wire. But you can just shorten them if you don't wish to remove them.
Hope that helps.
Attachments
Julien,
Two Questions:
1. What are the values for the 2 low voltage decoupling caps?
2. Did you replace the main board supply caps with 470uf or 680uf Panasonic FC caps?
Thanks
Two Questions:
1. What are the values for the 2 low voltage decoupling caps?
2. Did you replace the main board supply caps with 470uf or 680uf Panasonic FC caps?
Thanks
Stevenacnj said:
I used Panasonic FC 22uF/50V. I'm not 100% sure about the value, the value I used is the same as the original caps.
The supply caps I used in the modules were also Panasonic FC 680uF/100V.
The sonic improvements from doing these simple mods (including the input caps bypass) are astonishing. Yesterday night I listened to parts of Brahm's German Requiem, and later to Bomtempo's Requiem, and the rendition of the voices and strings was breathtaking. Of course, the rest of the system contributes to the sonic presentation, but the amp has a lot to do with it.
I've been also playing with ferrites both at the input and output of the modules. My conclusions so far are: Absolutely no ferrites at the output (speaker cables). The sound becomes "thin" and "brittle", it looses body. At the input the results are not so obvious. I think I prefer without ferrites. But I still have to do more listening tests to be absolutely certain about my choice.
ackcheng said:
I was never able to really appreciate Black Gates. Eventually I get tired of them, and yes I've let them burn in for more than 300 hours...
I'd suggest any good quality industrial cap. Look for the specs: impedance and ripple current. You want the lowest possible impedance and the highest ripple current. And remember, the maximum diameter of the main supply caps shouldn't be much larger than 18mm.
You can download Panasonic FC specs and use that as a reference when comparing caps.
Thanks for the info! I think I will try BG 10uF in parallel using the super-E configuration for the low voltage decoupling caps and see!
bypass caps.
I have posted a crude drawing of approximately what the circuit is you are dealing with. I traced all this out but can’t find my notes so it is a best guess based on memory. Only the + circuit is shown and the - is a mirror image of it with all polarities reversed.
Looks to be the perfect spot for an Oscon or similar cap with very low ESR. I would even consider adding a .1uf surface mount on the bottom directly across the leads.
Roger
I have posted a crude drawing of approximately what the circuit is you are dealing with. I traced all this out but can’t find my notes so it is a best guess based on memory. Only the + circuit is shown and the - is a mirror image of it with all polarities reversed.
Looks to be the perfect spot for an Oscon or similar cap with very low ESR. I would even consider adding a .1uf surface mount on the bottom directly across the leads.
Roger
Attachments
sx881663
You previouosly posted this:
"About the .68uf output caps, stacked film caps are not very good unless they have a lot of bias voltage on them to hold them solidly together. You actually get a smearing effect due to mechanical motion storing and releasing energy. This is why they are ok for power supply bypass but not very good for signal coupling. A properly wound cylindrical cap is far superior in this regard. This phenomenon also directly relates to microphonics. A quick and dirty test will reveal much. Charge up a cap to a known voltage then put a DVM across it, squeeze it and watch the voltage change. This is a measure of its microphonic properties. As expended energy this can even be audible. I have heard cheap Zobel caps sing like a bird while doing a frequency sweep.
What I did on my modules was to mount .68UF Auricaps with as short of leads as possible right on the back of the fast on speaker terminals. This did result in a higher level of the 500 KHz but it was a very pure sine wave and poses no interference problems. I think the extra pc trace length used contributes as much as the cap leads. I will experiment more on this later. Results are what count and they sound wonderful!"
Could you be more specific about this mod?
1. Did you remove & jumper out the .68uf electrolytic output caps?
2. Are there 2 of these output caps?
3. Where exactly did you mount the .68uf Auricap.
Anything else about this mod please let us know.
Thanks
You previouosly posted this:
"About the .68uf output caps, stacked film caps are not very good unless they have a lot of bias voltage on them to hold them solidly together. You actually get a smearing effect due to mechanical motion storing and releasing energy. This is why they are ok for power supply bypass but not very good for signal coupling. A properly wound cylindrical cap is far superior in this regard. This phenomenon also directly relates to microphonics. A quick and dirty test will reveal much. Charge up a cap to a known voltage then put a DVM across it, squeeze it and watch the voltage change. This is a measure of its microphonic properties. As expended energy this can even be audible. I have heard cheap Zobel caps sing like a bird while doing a frequency sweep.
What I did on my modules was to mount .68UF Auricaps with as short of leads as possible right on the back of the fast on speaker terminals. This did result in a higher level of the 500 KHz but it was a very pure sine wave and poses no interference problems. I think the extra pc trace length used contributes as much as the cap leads. I will experiment more on this later. Results are what count and they sound wonderful!"
Could you be more specific about this mod?
1. Did you remove & jumper out the .68uf electrolytic output caps?
2. Are there 2 of these output caps?
3. Where exactly did you mount the .68uf Auricap.
Anything else about this mod please let us know.
Thanks
Stevenacnj said:
Stevenacnj,
There is only one .68uf per module and it is stacked film not electrolytic. This cap is a very critical part of the output filter.
What I did was to remove the existing cap and replace it with an equivalent Auricap. This was their .68uf @ 450v unit. Outside foil lead (Black) connects to ground and the red lead connects to the output. Leads must be trimmed as short as possible. I attached it on the back of the circuit board where the fast on speaker connection terminals come through. I did this for mechanical strength.
Wish I could report on before and after sonically but the set up I had with this first unit was too hard to take apart for these kinds of tests. The next units will be a lot more user friendly due to a more open chassis. I will use this new amp as a test “mule” and plan to do a lot of tests. It shouldn’t be too long as I just received new 400 modules today.
Roger
sx881663 said:
Roger,
Did you notice a sonic improvement by upgrading the output filter cap to an Auricap?
I'm thinking about using a Sonicap in that location. I'm also thinking about upgrading my Panasonic bypass caps in the PS to Auricaps or Sonicaps...
Could you tell me what's your source of OS-CON caps in the US?
Thanks.
Questions
I could find no os-con source in a brief search but here is a possible source.
http://www.diyaudio.com/forums/showthread/t-58424.html
No, as stated, I did not do a direct a/b comparison. The unit I had to build was simply too difficult to work on to do this. I went by past experience on this. The more demanding the application the more the Auricap’s will shine! I have proven this over and over, sometimes replacing expensive after market units. There are some out there that sound great but are not neutral. I prefer my caps to not edit the sound. I have no experience with Sonicaps, first I have heard of them. I would have no objection to them if they are cylindrical and metalized polypropylene. This cap type is superior except for dielectric absorbsion. Teflon is superior in that regard but can have other problems that can limit its usefulness. This type of cap not only has superior test performance but is sonically more nearly neutral as well.
Roger
I could find no os-con source in a brief search but here is a possible source.
http://www.diyaudio.com/forums/showthread/t-58424.html
No, as stated, I did not do a direct a/b comparison. The unit I had to build was simply too difficult to work on to do this. I went by past experience on this. The more demanding the application the more the Auricap’s will shine! I have proven this over and over, sometimes replacing expensive after market units. There are some out there that sound great but are not neutral. I prefer my caps to not edit the sound. I have no experience with Sonicaps, first I have heard of them. I would have no objection to them if they are cylindrical and metalized polypropylene. This cap type is superior except for dielectric absorbsion. Teflon is superior in that regard but can have other problems that can limit its usefulness. This type of cap not only has superior test performance but is sonically more nearly neutral as well.
Roger
Julien,
"I'm also thinking about upgrading my Panasonic bypass caps in the PS to Auricaps or Sonicaps..."
Just to clarify, are you referring to bypass caps in your main PS or bypass caps on the UCD module itself?
Sonic Craft makes excellent caps. I have used them manytimes. They also make teflon caps which are reasonably priced (for teflon) and sound wonderful.
"I'm also thinking about upgrading my Panasonic bypass caps in the PS to Auricaps or Sonicaps..."
Just to clarify, are you referring to bypass caps in your main PS or bypass caps on the UCD module itself?
Sonic Craft makes excellent caps. I have used them manytimes. They also make teflon caps which are reasonably priced (for teflon) and sound wonderful.
SX881663
"To get back on track I am going to be replacing the 470uf caps on my modules with much larger ones. I will be using regulated supplies so am opting for 63 volt units that will be at 59-60 volts. These are about the lowest ESR units I could find (around 7 millohm). Do you think there will be a problem with ringing? If so would an RC snubber suffice, thinking of something like .22uf and .2 ohm?"
Which make and value did you use to replace the 470uf caps?
Thanks
"To get back on track I am going to be replacing the 470uf caps on my modules with much larger ones. I will be using regulated supplies so am opting for 63 volt units that will be at 59-60 volts. These are about the lowest ESR units I could find (around 7 millohm). Do you think there will be a problem with ringing? If so would an RC snubber suffice, thinking of something like .22uf and .2 ohm?"
Which make and value did you use to replace the 470uf caps?
Thanks
Re: Questions
Thanks for the link, Roger.
I like Auricaps myself. I've been using them for a long time now on almost everything, but I want to try the Sonicaps at the UcD400 output this time and see (hear) what they do to the sound.
Yes, the Teflon ones are the Sonicaps. I've never tried them, but I just ordered a 0.68uF pair for the output filter cap in both my modules .
I was referring to the bypass caps in my power supply, not the ones in the module's PCB (surface mounted).
I'm doing the upgrades slowly, so I can assess what part contributes to what.
Right now, my system is sounding so good that I don't want to rush changing the sound...
sx881663 said:
Thanks for the link, Roger.
I like Auricaps myself. I've been using them for a long time now on almost everything, but I want to try the Sonicaps at the UcD400 output this time and see (hear) what they do to the sound.
Stevenacnj said:
Yes, the Teflon ones are the Sonicaps. I've never tried them, but I just ordered a 0.68uF pair for the output filter cap in both my modules .
I was referring to the bypass caps in my power supply, not the ones in the module's PCB (surface mounted).
I'm doing the upgrades slowly, so I can assess what part contributes to what.
Right now, my system is sounding so good that I don't want to rush changing the sound...
Sonicap
Julien,
Teflon is a wonderful material for an insulator. It is so good that a static charge on it can last about forever. The problem with it is it is soft and don’t have a great deal of physical strength. This means that caps made with it can't be wound as tight and will have some mechanical give to them. The military versions get around this problem with metal jackets to shield and protect them. Unfortunately this totally screws up their sonics. I haven’t tested any commercial versions myself but would suspect things like a high level of microphonics as well as value change with applied voltage.
A cap is nothing more than 2 conductive surfaces separated by an insulator. Its value is directly related to the separation of these conductive plates. Any motion of the plates will change the value of the cap. With a fixed amount of charge on it this means the voltage must change as well. This is how capacitive sensors and microphones work.
The point is Teflon may not be that good of choice for this particular application where there is no DC and a lot of AC across the cap. The full audio output is across it as well as a bit of the switching frequency. Teflon really shines in tube applications where they have a large fixed voltage across them and may be exposed to high temperatures. This bias voltage creates a great deal of electrostatic force helping to keep the cap rigid and less microphonic. Extremely low leakage and long life make them the best choice here.
I know lots of words that don’t apply here but I would think useful knowledge to help make informed decisions for the proper application of these wonderful and expensive parts. If you do use them and can do an a/b comparison with a metalized poly type this would be useful information. Maybe all my worry is unfounded and these parts are even better than I think. Let us know.
Roger
Julien,
Teflon is a wonderful material for an insulator. It is so good that a static charge on it can last about forever. The problem with it is it is soft and don’t have a great deal of physical strength. This means that caps made with it can't be wound as tight and will have some mechanical give to them. The military versions get around this problem with metal jackets to shield and protect them. Unfortunately this totally screws up their sonics. I haven’t tested any commercial versions myself but would suspect things like a high level of microphonics as well as value change with applied voltage.
A cap is nothing more than 2 conductive surfaces separated by an insulator. Its value is directly related to the separation of these conductive plates. Any motion of the plates will change the value of the cap. With a fixed amount of charge on it this means the voltage must change as well. This is how capacitive sensors and microphones work.
The point is Teflon may not be that good of choice for this particular application where there is no DC and a lot of AC across the cap. The full audio output is across it as well as a bit of the switching frequency. Teflon really shines in tube applications where they have a large fixed voltage across them and may be exposed to high temperatures. This bias voltage creates a great deal of electrostatic force helping to keep the cap rigid and less microphonic. Extremely low leakage and long life make them the best choice here.
I know lots of words that don’t apply here but I would think useful knowledge to help make informed decisions for the proper application of these wonderful and expensive parts. If you do use them and can do an a/b comparison with a metalized poly type this would be useful information. Maybe all my worry is unfounded and these parts are even better than I think. Let us know.
Roger
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