[bluesky]

Hi Everyone

I am in the process of building some Aksa products and considering adding some small bypass caps on the electros on the underside of the PCB's as well as alternatives for the original MKT/P's.

I know, Ginger, an EE who really does know his stuff, recommends bypass caps on every electro, this is good enough for me!

There are a squillion opinions on caps out there on the internet, I take these with a grain of salt (well, maybe a whole bushel of salt) and I wait to see a good consensus of opinions before making any buying decisions on parts.

With that out of the way, my thinking is to try out some Wimas or Vishay MKT1822's as a cost effective and practical way of adding a small improvement to the electros or to "upgrade" the original small value caps that are supplied with the kit.

Has anyone tried this and also any impressions of the sonics of the various caps.  I know that some have used Platinums but this is way outside my budget, although a couple of premium Obbligatos might be possible and their smaller physical size could suit this application better to mitigate against hum pickup.

Any suggestions would be much appreciated, even it is to not bother and waste my money chasing rainbows.

Bluesky

[AKSA]

Ian,

Try the 1837 Vishays, but they are expensive;  RS Components sell 'em in Brissy.

They will have greatest effect on the sound of the LF55 on C4, (to immediate left of P2), and C7 (the bootstrap cap).

The rail caps will have almost zero effect, unfortunately.

Cheers,

Hugh

[Occam]

I also use the MKP1837, a .022uf as a bypass of C1?, the input Evox/Rifa MKT .47uf. These are both 5mm lead spacing caps and I simply solder the MKP on the mainside and tag solder the larger .47uf on the underside to a couple of mm left on the MKP1837 leads. It makes for a compact simple mod.

FWIW,
Paul

[bluesky]

Hugh, Paul

I suspected there would not be a great deal of improvemnt to be had by this idea.  I also thought if this idea was so great how come it hadn't become part of Aksa folk lore?

The MKT1822's can be had for under a dollar in some places and at that price you could try them out without having too much anxiety about wasting a lot of money.  I have found that bypass caps have been quite effective in a couple of upgrades I've done for friends which resulted in quite audible, and positive, sonics.

I also know that Hugh tries just about any combination of caps in voicing his amps and if there was any great benefit he'd be onto it.  If I do end up trying this out I will certainly post my impressions of the results.

Cheers

Bluesky             

[kyrill]

Hi Paul

Did you had time to listen to the teflon Russion 0.22uF (big metal housed) capacitors?

[Occam]

Hi Paul

Did you had time to listen to the teflon Russion 0.22uF (big metal housed) capacitors?

Now I'm embarrassed (hence the delay in responding).
No, I've not implemented the lovely teflon caps you so graciously, and generously sent me. Much to my family's shame, I've become a purveyor of power cords and conditioners, and other things mystical.
As my system is used for evaluation of the minute changes of these upstream changes, at this point, I cannot have a system that endures an awkward and painful adolescence, even if it ultimately blossoms into a self actualized adult.

Regards,
Paul

[SamL]

Hi,
Question about cap. I replace the 2000nF ceramic (I think) cap on my TDA1541a DAC opamp I/V board with silver mica with good results - improve clarity. I am wondering if polystyrene will outperform the silva mica or should I continue replacing the rest with silva mica?

[AKSA]

Sam,

My take on this:  If the signal is ultrasonic, cleaning up artefacts in filters for example, then silver mica is tops because the HF behaviour is so good.

BUT, it's very bulky.

For audio only, polystyrene is the best choice because dielectric absorption is very, very low, reducing time smear distortion (memory effect).

Hugh

[bluesky]

Hi Sam

There is a thread on Audiocircle regarding the MKT1822's and in this it was stated that Walt Jung et al determined that the pecking order of caps was teflon, then polystyrene and then there's the rest.  I can't recall where silver mica is on this list but it is pretty high up.

One of the reasons for this thread is that I have developed some advanced scrounging skills and can sometimes get free stuff from friends who are retired technicians as well as sources like Ebay and surplus suppliers.  It was with this in mind that I sought any advice/opinions about the worth of bypass caps or changing the original MKT/P's with parts that may provide some improved sonics.  However, I also did not want to be "chasing rainbows" by putting in parts that would not make a scrap of difference.

I hope to be visiting a chap soon who recently retired from running a small one man electronics repair shop and he has generously offered to give me a bag of parts to use in my audio projects.  This chap actually wants to clear out some of his "electronics junk" to please she who must be obeyed, how lucky am I!  

I am also fortunate this week to be living in the more northern parts of Australia, positively chilly compared to Melbourne, where they are in for a week of extreme temperatures, poor Hugh will be sweating this period out.

Bluesky

        

[SamL]

The cap is connected between pin 2 & 6 of the opamp. From my limited skill, It looks like the signal path. The mod was not intentional, the cap was replace as one of the stock cap was wrong value and silva mica is the only thing I have. The high do open up with better clarity specially in cymbal, I think I'll leave silva mica there. But for the other opamp AD797, I might replace it with polystyrene cap. I think that will go well with it. Oh yes, this I/V uses 4 x single opamp... I hope this not making some of you cringe.
Well, you are lucky Bluesky be able to get free/cheap parts. Not so lucky for me here in NZ
On the bypassing cap side, do you or anyone think there any good to bypassing the 14 x 0.1uF on the TDA1541a DAC?
http://www.audiocircle.com/index.php?action=gallery;area=browse;album=109&pos=3

[bluesky]

Hi Sam

I am not the person to ask about such things as they are beyond my (very) limited skill levels!

However, you may wish to have a look at Lukasz Fikus' website which has heaps of information and links about this DAC as per this link:

http://www.lampizator.eu/LAMPIZATOR/TDA1541%20corner/TDA1541.html

Hugh has made a suggestion regarding a possible parts upgrade but I get the feeling that there is not an awful lot to be gained by throwing a lot of bypass caps into the mix.  If you are chasing parts on a budget you can keep an eye on the Vintage Electronics section of Ebay where you can often find parts at bargain prices.  I think it suits both sellers and buyers, the sellers can clear out some old parts and get a few dollars for them and the buyer can pick up some decent parts for a good price.  It is also worthwhile to seek out people such my retired tech friends, they have built up a lifetime of skills and knowledge and appreciate it when they find someone who genuinely values their knowledge.  In these modern times a lot of technician type people have a very narrow focus in a specialist area whereas "in the olden days" they had to solve any problem that came into the workshop.

Hope this helps,

Bluesky
 

[VYnuhl.Addict]

The cap is connected between pin 2 & 6 of the opamp. From my limited skill, It looks like the signal path. The mod was not intentional, the cap was replace as one of the stock cap was wrong value and silva mica is the only thing I have. The high do open up with better clarity specially in cymbal, I think I'll leave silva mica there. But for the other opamp AD797, I might replace it with polystyrene cap. I think that will go well with it. Oh yes, this I/V uses 4 x single opamp... I hope this not making some of you cringe.
Well, you are lucky Bluesky be able to get free/cheap parts. Not so lucky for me here in NZ
On the bypassing cap side, do you or anyone think there any good to bypassing the 14 x 0.1uF on the TDA1541a DAC?
http://www.audiocircle.com/index.php?action=gallery;area=browse;album=109&pos=3

Hi Sam,

   The cap that your writing of is wired from opamp output to its inverting input, this is a phase lead cap and this allows it to drive capacitive loads by limiting its bandwidth at very high frequencies. Silver Mica is very superior in this role, and as Hugh has stated superior  in Dac filters too, along with polystyrene. For the TDA1541 or any DAC, if its the digital power supply I would not recommend anything other than Multilayer Ceramics for the small values 0.1uf, I have always found these to be the best choice for Digital supply bypassing. The analog section is where you dont want ceramics, so replacing with a good film cap of your choice will be sonically beneficial..


Regards
Colin

[SamL]

Thanks Bluesky for the link and tips. Mine is Thomas's DAC, which DiyHiFiSupply base theirs on. There lot of info & ideas in Lukasz site and this will keep me busy for sometime
Thanks Colin & Hugh for the valuable info. I read a lot about polystyrene but never know silva mica can be good in signal path. Looks like my ear is telling the truth.

[VYnuhl.Addict]

Hi Sam,


     Just read some of his site, I think downloading the datasheet for your chip will be most beneficial to you and study it well. There are some key areas that benefits can be gained although they may be subtle dependant on the quality of I/V and buffer stage in the analog domain. I would strongly recommend though sticking to the datasheet values in the digital section will keep it within its operation specs without deterorating performance potentially. Digital power rails will greatly cbenefit from 100nf, multilayer ceramics, these are much more stable than those cheap discs, aka as monolithic caps too. The cap across the oscillator 470pf shown in the datasheet seems to like a Silver mica here. all others you can experiment with quality films. The 100nf stacked with a 220nf could be a bit dubious, and hit and miss, there is great potential with the close values to cause problems at high frequencies on the digital rails that can inject more noise than it helps eliminate. As a general rule of thumb if you need to stack caps kee to a minimum of 1/10th the value, 100nf, stacked with a 1uf. I personally like to keep them farther apart to guarantee no issues, 100nf/4.7-10uf...If you have to duble up 2x100nf will be much better than 1oonf/220nf together, and I have found will sound better too.



Colin

[AKSA]

Thanks Colin,

That's marvellous advice! 

Cheers,

Hugh

[SamL]

Hi Bluesky, hope you don't mind my rude intrusion to you discussion tread. 

Hi Sam,
     Just read some of his site, I think downloading the datasheet for your chip will be most beneficial to you and study it well. There are some key areas that benefits can be gained although they may be subtle dependant on the quality of I/V and buffer stage in the analog domain. I would strongly recommend though sticking to the datasheet values in the digital section will keep it within its operation specs without deterorating performance potentially.

Great idea. Have download and reading it.

Digital power rails will greatly cbenefit from 100nf, multilayer ceramics, these are much more stable than those cheap discs, aka as monolithic caps too.

Well, checking my DAC circuit digram, there no 100nF cap on pin14 but at the same time I am not sure where it end. The pin connect to a 'delta' which I am not sure where/what it is..... my limited skill starting to show here. 

The cap across the oscillator 470pf shown in the datasheet seems to like a Silver mica here.

The current 470pF cap is a glass looking translucent yellow colour cap. Not sure what type of cap it is, can it be silva mica? I do have a 470pF silva mica on hand.

All others you can experiment with quality films. The 100nf stacked with a 220nf could be a bit dubious, and hit and miss, there is great potential with the close values to cause problems at high frequencies on the digital rails that can inject more noise than it helps eliminate. As a general rule of thumb if you need to stack caps kee to a minimum of 1/10th the value, 100nf, stacked with a 1uf. I personally like to keep them farther apart to guarantee no issues, 100nf/4.7-10uf...If you have to duble up 2x100nf will be much better than 1oonf/220nf together, and I have found will sound better too.
Colin

That is what I was thinking before knowing the Lukasz site. For the bypass, I will only use what I currently have. Will be a long time before I have extra $ to spend on mod.
Again, thanks for you insight skill/knowledge in this area.   

BTW, anyone here tried the surface mount cap?  I replace a set of the 10uF surface mount cap on the I/V board with same value Muse SE (non pola) and it is not as good as original. Music is a bit slower, less details and not as musical. Had it for 2 days and it is off. Spend 20min to solder two tiny SMD cap back, but its is worth it. Never though SMD cap to be any good.. or it is just me??? 

[bluesky]

Hi Sam

It was good to hear your feedback regarding the surface mount components.  I have found it is all too easy to be taken in by some opinions that we must throw a lot of money at exotic caps which cost huge sums of money to get good music. 

The real situation I have found over the last few years is that design is everything.  Adding such parts is very much the equivalent to seasoning in cooking, or perhaps, changing cables in your system.  Items such as bypass caps and diodes can add a bit more sparkle, speed and clarity but the component must be fundamentally right in it's design before adding any of these upgraded components.

I have also been thinking of late that I don't see much around on high end surface mount parts, probably because most DIY hobbyists find their tiny size daunting to work with compared to the usual discrete components.  I suggest that you become familiar with places on the net that sell parts like Ebay vintage and electronics section as well as surplus suppliers in the States such as Apex Jr and Electronics Goldmine etc where you can often find parts very cheaply indeed.  The polystyrene caps for instance can be sourced for a few cents each in some cases and shipping is also cheap when it's in an envelope!

Good luck with your DAC

Blesky