[MikeW]

I thought alot of people replaced the Digital Decoupling caps in the old Valab.. the little blue polymer caps all over the digital board. I thought this was the same thing. Looks like i got bigger problems though with this ac all over the place. Wonder if I should try to replace the voltage reg.

Can anyone verify this is the right part?

http://www.mouser.com/ProductDetail/...lgGaGDB8fyY%3d

Quote:

Like Qusp mentioned a couple pages back you have to be careful about digital signal integrity when you go messing with the surface mount caps and resistors in the digital path. IMO most of these bits are best left to the experts as you can do more harm then good.

 

[Wood]

Quote:

Originally Posted by PatOMalley /img/forum/go_quote.gif Triple bypass? Ya think? I am not so sure removing them is the wrong thing to do. You usually bypass a poor cap with a better cap but in this case that is reversed. If you use a good capo then you do not need a bypass. Hmmm. Maybe bipolar is the way to go and remove the bypasses? Nichicon has 'em.

I will try it on my valab, use some wimas to experiment, once those smd are of there is no going back. dont see why it cant work though?

 

[rhodes54]

Quote:

Originally Posted by MikeW /img/forum/go_quote.gif Where can you buy Os-con's in the needed Capacitance, oh yeah that's another thing, I did keep all the Capacitance values the same as what I replaced, only 2 values. 10uf and 100uf.

I bought them at Farnell. The have both values on stock (Farnell Europe at least). Be sure to take the OSCON SP (Or SEPC if you can find them). They work best in a digital signalpad.
Since yesterday I started to notice that the sound becomes more transparent. This also happened when I did the Oscon job on the digital part of the Valab.

If you go for transparency do the "Oscon job", if you like brown and smooth, leave those Tantulum caps in

Cheers!

 

[PatOMalley]

Copped to the FRM mod [which is the ERM mod for me] and gained more control and focus but living with the thickness of the BlackGate. Crazy how that cap is so thick at startup. I see that Bill used a combined 20uF. Those BlackGates are 470 and have to be up to the job of power reserve with that depth and at 16v they cover the volt range.

Here is the output mess with that BlackGate standing guard on the left. I am tempted to do the simple output mod form the DAC to the cap using the existing resistors. They are just sitting asking me to just do it. Hard to resist.

 

[Bill Allen]

Pat- once again nice picture of how to wire the FRM mod ... or ERM in your case. Once you replace your DCPC (DAC Chip Power Caps) I would recommend you revert back to the Wima FRM, heck you might want to try it now and let us know how it changes the sound.

Yes from this same angle you will be able to clearly show the SSOM when your Z-I/V's show up. Ideally you should run separate ground wires from each RCA jack back to the SPG (single point ground). I see yours is bussed together but you do have it attached at the recommended SPG.

I don't think I could add another acronym. (IDTICAAA)

 

[marcelnl]

anyone here tried Allen Bradleys in the digital section? they do have a spot on pulse perormance......

 

[hifi2001]

Tried Tony's FRM (Film Reservoir Mod) Friday night and yes it did bring out the liveliness from the Chamelon, BUT, I later noticed I lost some bottom end from the DAC which mine system doesn't have tons of bass to begin with... so out FRM comes and my bottom end came back!
Then it occurred to me why not add more capacitance but using electrolytic caps? We all know that film caps are fast and electrolytic caps are relatively slower, but each have it own merits...
After some experimentation, I have now settled with Tony's FRM + 2 x 220uF Pana FM caps connected to 7.5 and GND as shown in the pic. I call it FRM++ (++ for the 2 220uF caps). I did go as high as 2200uF but found the sound a little booming.
Give it a try and report back what you think.

 

[marcelnl]

adding capacitance is not always a solution that works, you need speed too and for that film caps are good but not everywhere.
Lots of digital circuitry calls for caps that are no good for analog purposes and many chip producers dp provide sound advise in their spec sheets as to capacitance and type of cap.
Adding 10 *220 uF usually beats adding 1*2200 uf.

 

[PatOMalley]

Quote:

Originally Posted by marcelnl /img/forum/go_quote.gif adding capacitance is not always a solution that works, you need speed too and for that film caps are good but not everywhere. Lots of digital circuitry calls for caps that are no good for analog purposes and many chip producers dp provide sound advise in their spec sheets as to capacitance and type of cap. Adding 10 *220 uF usually beats adding 1*2200 uf.

The increased capacitance on the FRM mod worked for me, no bass loss. It does look like hifi2001 has his caps connected to only one DAC instead of to the incoming power 7.6v rail. So he is only reserving power onto that one chip?

 

[Bill Allen]

Norm- interesting results however I notice you don't have the 47uf FK Blackgates on the DAC chips. Do this then the FRM will do its job.

Understand everything we do to the DAC chip power supply will directly change the sound at the analog output as the stacked DAC chips are our onboard amplification. Balancing this equation is a tough nut to crack and the sky is the limit on how to do this. Look at what Rhodes did for his Valab and what he is proposing to do for his Chameleon power supply.

A friend installed some low ESR 47uf United Chemicon caps to his Valab DAC chips and it rolled off the highs. Here is a link to some other choices if you want to roll the dice and save some money.
Badcaps Forums - What capacitors should I buy?

For now the Blackgate FK caps with FRM are the proven concept but are pricey at $5.25 each.

 

[MikeW]

I put all the SMD Tant's back on the digital board and reclocker for now. Cleaned the whole thing up with 99% alcohol, looks better then new. Mostly did it for sanity sake, at least now I can focus in on the other mods and the way the effect sound without having to worry about if that one is "right" or not. I may experiment with those caps again in the future, maybe someone else can take a leap there, I don't want to buy expensive Oscon's for no good reason.

I am however concerned with this AC issue. It's definately coming from the DC30. I don't know where to start to fix it though. Is changing out the voltage reg for a brand new one of the same part recommended? I guess it can't hurt, it's only 99 cents.

I took that capacitor out of the DC30 as it did not seem to be doing anything afterall, I measured before and after and get the same readings. Before when I measured the DC30 with the cap in line, it was with no load, and no AC showed up, but as soon as there is a load it comes back.

I did measure my SPDIF source and it definitely puts out DC offset. Can you partially do the FIM? Ie, just hook the ground wire to the transformer and leave the primary the same? This way you get "Floating Ground" and a filtered primary.

Also, did I read it correctly when it was said earlier in the thread that the 0.01 K40Y is to low a value and should be .1UF instead?

Most of you have more experience with this then I do, I am still learning a lot, and I appreciate all your help.

Edit: i took out the Wima 20 uf's FRM, I don't know if it's unburned in caps, or synergy, but to me it sounds better without it. I lost quite abit of detail. The Silmic 2's are fairly warm already. perhaps to much of a good thing, I will try this with a higher UF electrolytic.

I also measured the DC voltage of all the caps on the Digital Input and Reclocker board, they range from 1.8v to 3.3v and 5v at the highest. So 6.3 v replacements should be fine.

 

[driguy]

Quote:

Originally Posted by PatOMalley /img/forum/go_quote.gif The increased capacitance on the FRM mod worked for me, no bass loss. It does look like hifi2001 has his caps connected to only one DAC instead of to the incoming power 7.6v rail. So he is only reserving power onto that one chip?

OK, once more I will tackle this. Already two people have done this differently than it is designed and magically it did not work for them. Yes Pat, those caps are in the wrong spot. Now they are trying to act as a current reservoir for all the DAC chips but the current trail is now much smaller and more convoluted than before. Please, if you do this mod, solder in the cap(s) at the jumpers going to the DAC chip board as previously described. Try to keep the positive lead (even some non polarized caps have a preferred lead) as short as possible. The negative lead is not nearly as critical. To re-iterate, this is no longer a filter cap, it is a current reservoir so different caps will give you different results than they might in a filtering situation. These are much closer to being part of the signal path much like the power supply of a tube amp. Yes, the BlackGates are nice and fast, hence they work well at the DAC chips and other spots but I have replaced them in spots like this with film caps of a much lower value which resulted in much better sound. Of course, YMMV.
Pat, if you can follow Bill's suggestion and try the Wima's I will be curious to see if this holds true in this particular instance. If space is a concern just wrap the cap with tape and lay it in there especially if you are just experimenting. Have fun with it.

Tony

 

[Wood]

Quote:

Originally Posted by marcelnl /img/forum/go_quote.gif anyone here tried Allen Bradleys in the digital section? they do have a spot on pulse perormance......

Yes I am using them at 180r 2w versions, but as IV. Very natural, balanced sound there, but clearer then normal carbon comp. So I Imagine they will work well in the digital by not leaving an impression.

 

[Wood]

driguy, the nice thing about Wimas, apart from the fact we can recycle the stock ones, is they are cheap. I will experiment with using Wimas as bypass caps in various places and report back. Just gotta wait for the shop to open. Point has been proven again that significant benifits can be gained, with a bit of applied intelligence as opposed to relying only, on piles of dosh (although must admit that can be handy sometimes as well). So simply, if it doesnt work pull it out again.
Thanks for opening up a new country to explore.

 

[PatOMalley]

Quote:

Originally Posted by driguy /img/forum/go_quote.gif OK, once more I will tackle this. Already two people have done this differently than it is designed and magically it did not work for them. Yes Pat, those caps are in the wrong spot. Now they are trying to act as a current reservoir for all the DAC chips but the current trail is now much smaller and more convoluted than before. Please, if you do this mod, solder in the cap(s) at the jumpers going to the DAC chip board as previously described. Try to keep the positive lead (even some non polarized caps have a preferred lead) as short as possible. The negative lead is not nearly as critical. To re-iterate, this is no longer a filter cap, it is a current reservoir so different caps will give you different results than they might in a filtering situation. These are much closer to being part of the signal path much like the power supply of a tube amp. Yes, the BlackGates are nice and fast, hence they work well at the DAC chips and other spots but I have replaced them in spots like this with film caps of a much lower value which resulted in much better sound. Of course, YMMV. Pat, if you can follow Bill's suggestion and try the Wima's I will be curious to see if this holds true in this particular instance. If space is a concern just wrap the cap with tape and lay it in there especially if you are just experimenting. Have fun with it. Tony

I chucked my Wima's after pulling them and I will shorten that leg after doing then SSOM mod. Just wanted to leave the cap in position to remove it easily. I will drip it flat to the board and connect the jumpers to the bottom of the DAC board at the caps pins - can't get no shorter than that. I can also bypass the BG with a .01 under the board and may do that, maybe.

For the individual DACs I think bi-polar may be my choice, or Fine Gold with leaving the bypasses in place. I will wait to hear back on someone who is removing the bypasses on what they get.

How fast does the cap have to be? /w 470 uF on reserve a draw won't deplete that cap and so the recovery for it is not as would be for a 20uF cap if another draw were to happen. The BG has enough reserve to do the job and is suited to power supply work, or that is what I am thinking.

There was a rule in play talked about some time back where you use diminishing percentages for the values as you go down the rail. So 10% of 470 is 47uF for the DACs and that matches that rule ... unless I misquote it.