Oscons tend to be DC leaky especially the polymer based variety so I'd be cautious using them for coupling, work nice decoupling digital IC's or XO's though.
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Oscons tend to be DC leaky especially the polymer based variety so I'd be cautious using them for coupling, work nice decoupling digital IC's or XO's though.
How much worse are they than any standard wet electrolyte electrolytic? I mean they all leak to a certain extent though we should be talking micro Amperes in reality.
Do you happen to know how much worse the solid electrolytics (SEP) are by chance? 10%? 100%? Sorry, i gots to know :eyebrows:
Cheers in advance Leo :)
Agreed, Leo, I also prefer the grey Rubycon CE types, which are still in circuit.Quote:
Originally Posted by leo
Those are next on the list Ali :)Quote:
Originally Posted by Ali Tait
Hopefully by then curiosity will stop getting the better of me!
Tried to source some of these, bloomin hard to find!Quote:
Originally Posted by MartinT
Are they not being made any more?
I remember there was a group buy from the States to get them for upgrading the opamp board...but that was a while ago.
Aye,at least they are cheap,I've got the SCR's in now,which cost more than the dac!
Hey Mark,Quote:
Originally Posted by Reid Malenfant
your comment about the voltage got me thinking...
As there didn't seem to be any concensus about voltages (as opposed to uf) for the caps for this application, and believe me I checked(!), I guess I tried a variety of values as they were just a few pence to buy.
Your comment though about 50v giving better performance due to lower losses...does this apply across the board with all opamps in this case or just the Sanyo solid electrolyte ones you spoke of?
Always keen to learn about this stuff! :)...:scratch:
Going by the different choices of cap made here, I guess like most hifi stuff it comes down to the individuals ears!
Is there a general concensus though about "best voltage" for caps for the passive output mod for the dac?
ta.
DP
Hi Gaz, it applies to all electrolytics & to a certain extent non electrolytic capacitors ;) The higher the voltage rating of the capacitor the less losses you'll get, less DC leakage current & you'll find that 99% of the time that capacitor ESR (equivalent series resistance) is lower as well.
In a way it's pretty obvious, a capacitor that is designed to have a maximum of say 25V accross it is manufactured to have a leakage current within certain limits. If you substituted one of lets say 4 times the voltage rating but kept the maximum voltage accross it at 25V or less then you'll get much less current leakage as that cap should have been designed to leak about the same as the 25V cap but at 100V ;)
Give it 25V & the leakage current should be 1/4 of the 25V cap...
I'd like to point out that all capacitors should be "formed" or in the case of an older cap, "reformed". This involves something as simple as a regulated power supply set at the maximum voltage of the capacitor & a high value resistor or current regulation to gradually charge the capacitor up before you ever use it. Obviously discharge through another resistor before fitting it into a circuit :doh:
Doing this should give you maximum capacitor performance by reducing leakage currents :)
Easily the best I've tried,but then I'm enjoying the Audio Note coppers in the AN dac too.
The leakage was enough in one case it set off an amplifiers DC protection on the output.Quote:
Originally Posted by Reid Malenfant
I've repaired quite a few item belonging to friends mostly what they'd modded themselves , Sanyo Oscons they fitted caused majority of problems ranging from DC leakage when used as coupling caps or used in the FB to high frequency instability when used on the output of LM317 based regulation caused by the low ESR.
Oscons are good caps but after previous experience I feel care is needed if using them, they can in some cases cause the inexperienced tweakers headaches :)
Cheers Leo, a pretty comprehensive answer ;)
A good bit of thought obviously needs to be put into if it's wise to use them then under certain circumstances :eyebrows:
too rich for my blood! :)
Greetings All
I have read this mod. with using caps only and removing the OP board.
I have a 7250 which has 826 installed. I have a pair of REL caps from my Atma-Sphere MP3 pre amp. I have a pair of .10uf and .47uf 400V. Can I use either of these caps as coupling caps in my 7250.
Thanks
Bryan
Depends on the input impedance of you preamp/amp.Do you know what the value is?
Hi BryanP,
Ali is correct about checking the input impedance of your amplifier, but it is most likely that those capacitance values are too small and would end up filter out a noticeable amount of bass.
Andrew
The 0.47uF should be fine for a preamp with a 50k input impedance.
Agreed Clive,I'm using 0.47uF with my WAD Pre 2,which has an input impedance of 100k.
Greetings All
I installed the REL-Caps .47uf 400 volt. The improvement to the sound is wounderful. I am a believer!!
Much more open and detailed bass.
Works great into my PS Audio PCA-2 pre-amp
Thanks for the info.
HI,
As I got carried away with success and good SQ with MLC5/6 mod I also wanted to try passive output mod as it seems quite simple and I had some spare caps.
Anyway, it was not that simple as after doing this fiddly job only one channel was working (right) and I also did not like the sound as much as with opamps hence I wanted to return to normal opamp mode.
After de soldering the caps and bridging the RCA sockets, there is not sound anymore coming either from fixed, variable and headphone outputs.What could be the problem?
Thanks
Which implementation of the passive mod did you carry out? There are several versions that do the same job. A couple of pictures might be most helpful.
Can anyone tell me what this mod does to the standard 7510 with PCM 1716 chip?
http://i73.photobucket.com/albums/i2...510wiremod.jpg
Try it and see :eyebrows:.
I thought I had an updated picture that showed the soldering away from the DAC chip pins. It's best not to solder the wire directly to the DAC pin. If I can't find my other picture, Use a multi meter to trace a better spot from the wire on pin 15 of the PCM1716.
I did the mod from the post 1 of this thread.Quote:
Originally Posted by StanleyB
Shall I send photos too?
Regards
I can't see any reason why the sound should be dead if you reversed the mod. Was the DAC unplugged from the mains when you were working on it?
Hi,Quote:
Originally Posted by StanleyB
Yes, I also can not see the reason for DAC not working after reversing the mod.
DAC was definitely unplugged from the mains when working with it.
The DAC lights come on, and work fine, as well as tiny popping noises when switching inputs (when volume is at max).
Are ALL the pins on the daughter board/audioboard inserted into all the socket holes?
TBH it would have been easier for you to try inserting the caps into the dacs onboard sockets (post 117) http://theartofsound.net/forum/showt...t=6910&page=12 when trying the passive mod, I'd then do the cutting sockets etc if you wanted to keep this mod permanent
What are the daughter/audioboard pins? Is the daughter board one where the opamps are placed?Quote:
Originally Posted by leo
I just realised that would be definitely easier if I have read post 117 earlier and tried passive mode that way.
With passive mod from post 117, do you need to cut RCA connectors?
But the main problem remains, there is no sound:scratch: coming out of Beresford :(
Only the blue lights and popping noise when switching the inputs (at max volume only).
Could it be that main DAC chip can not stand the hot temperatures from soldering iron (it wasn't touched by iron, it was in close proximity).
Any help, please?
The audioboard is the credit card sized pcb containing the op-amps etc seen in this first pic http://theartofsound.net/forum/showthread.php?t=3058 , its plugged into a multi pin plug/socket. Its just an idea to be sure its plugged in properly elliminating the possibility its been knocked loose when you was trying the mods.Quote:
Originally Posted by RoboCopper
If you did the passive mod correctly the dac should work so we'll need to see some detailed pics to help us diagnose your problem, it could be a number of things causing it.
Are you sure you didn't short any of the signal tracks out when doing the mod ?
I checked the audioboard with opamps and it seems to be correctly fitted. Pictures will follow tomorrow at the daylight for better quality :)Quote:
Originally Posted by leo
I think I did not short any of the signal tracks.
If I short two signal track where I was soldering, there wouldn't be no sound coming through, would it?
But at the highest volume I can hear slight popping noise when switching inputs, especially from USB to coax1.
Is the chip DAC to blame? I guess that signal goes from digital inputs to DAC chip, thank via those cables to other front bigger board, than to opamp audio board, than back to front bigger board and back to rear board and then to RCA outputs?
I just checked by touching the connectors where I have soldered the capacitors for the mod from the post 1 of this thread and when touching with small screwdriver the speakers are producing the crackling sound, meaning that there is some signal coming from that point, also when touching the opamps board, same sound is coming out.
Could something be wrong with input stage of the 7520? Static?
p.s. I also used can spray for blowing air in order to clean all possible shortcuts (e.g. under the DAC 1716 chip).
Here are some photos.
Can you provide a picture of the back of the fixed RCA socket? It is not clear whether you have soldered them back correctly.
So this takes power straight to the +5v IN. I suppose you could make a separate PS for it?Quote:
Originally Posted by StanleyB
Hi, I think they are, but here are more photos.Quote:
Originally Posted by StanleyB
Regards
I've finally decided to do my first ever mod! I hadn't realised I could do this without soldering anything, so ordered some Rubycon Bi-polar 47uF caps from Tirna, (4, just in case, I know what I'm like...) and then I can see what the fuss is all about by taking the op-amp board out. The only slight downside is losing the Headphones, but I only use them rarely anyway, and I can always get brave and do the other method if the headphone out on the Creek is awful...
Should be fun, can't wait to see how the mod sounds.
Are you sure the phono socket is making a good connection with the phono plug? One looks rather fried.Quote:
Originally Posted by RoboCopper
Alex - allow a full week for the capacitors to settle down. Rubycons are a good choice. You should hear a sizeable improvement over the op-amps provided your preamp/amp's inputs are high impedance.
Thanks Martin - I'll do what you do I think, and leave it running 24/7 with Sky - if they should make it here tomorrow that would be great as we are away for a few days. I'm actually also hoping the output will be a bit lower because the Phono board I've fitted is noticeably lower than the Caiman currently, so might even things up a bit and stop me waking the neighbours when I switch from the turntable! No idea what the impedance is on my Creek amp as it doesn't say in the manual, although all line-level inputs are said to be the same 415mv sensitivity.
I wish that was the problem, but there is no sound coming out on variable RCA outputs (and fixted) where I did not touch them at all.Quote:
Originally Posted by Clive
In fact there is popping sound coming out of fixed ouputs, but only when volume is at max volume and when switching the inputs.
Thanks for suggestion though.
It looks very much that the DAC chip might have succumbed to static electricity failure.
Although I did not touch the chip DAC with big soldering iron, static electricity could be to blame.Quote:
Originally Posted by StanleyB
But I thought of upgrading this chip anyway, hence if I find good technician with soldering skill this could cure my lovely 7520 (which is becoming a Caiman)
:)
Sorry, my mistake. The Caiman does not have any such modification. It is for the TC-7510 and details can be found in the TC-7510 mod thread.Quote:
Originally Posted by Puffin
Sorry Stan you have lost me:scratch:Quote:
Originally Posted by StanleyB
Mine is a 7510. So is a separate 5v supply to that pin reccommended? I assume the wire mod picks the +5v off the tant?
Rob.
This is the Caiman thread :eyebrows:. In order to comply with AoS rules, you should be posting the question in the appropriate thread. Otherwise some readers of the thread are likely to get confused and start to think that the mod is also related to the Caiman, which it is not.Quote:
Originally Posted by Puffin
Yes Stan, I completely forgot. Same question different thread. See you over there.
Rob.
Hello All,
Have any of us try the passive mod with 2 series bipolar capacitors per channel? I tried it and felt that the sound is better. Not sure if it is just me and suggest you try it and share your experiences.
This idea came about from an article I read about having 2 bipolar caps in series lowers the distortion by 5 to 10 times...wow. Try it to see if it works for you.
:band:
Hi all,
Just wondering whether anyone is considering using a Lundahl line output transformer instead of caps? E.g. http://www.lundahl.se/pdfs/datash/1585.pdf
If so, can anyone advise me whether the centre connection in PIN3B could be used as a ground?
Andrew
There is a 2.5V DC component on the output of the DAC chip. So without the cap you are going to short the DAC chip to ground.
Some time ago I designed a discrete stage. Leo built a copy of it on stripboard and he had good results with it. My version has the headphone section using an opamp for convenience, but the line out is discrete.
http://www.homehifi.co.uk/images/mods/discrete.jpg