[mrdon]

I would agree with everyone here. The two most cost effective tweaks are located in the power supply and in the output stage.

The power supply mod is fairly straight forward. Find the section on the pcb where the power supply 'lytics are located and write down all their values. Maintain (or increase) voltage but increase capacitance by 20% except for the big can cap - double it. You can use Black Gates (mucho $) or Panasonic FC's (inexpensive). Also, find your diodes and replace them with over spec'ed
Shottky diodes. Next or close to your diodes are the X "safety" caps. They should stay the same size, unless you're going to try the Auricap tweak. In that case, replace each X cap with a .47uF/600V Auricap. All of this improves power recovery and cleans up grunge. Better dynamics is the first thing you will usually notice, as well as a deeper and possibly tighter bass.

The second best place to make changes is in the analog path, after the DAC chips. Better caps here can help a lot, and can change the sound significantly, especially in the top end clarity, extension and transparency. You can also roll in some higher quality opamps (remember to check voltages) and exchange the very last 'lytics in the path with film caps (like Auricaps). At this point in the path, you may also exchange the stock resistors for higher grade ones like Riken carbon films.

Please note...you do this at your own risk and at the risk of potentially harming yourself and your equipment. That's the risk involved but the risk IMHO is worth it to the ears God gave us.

 

[Teerawit]

Quote:

Originally Posted by mrdon The second best place to make changes is in the analog path, after the DAC chips. Better caps here can help a lot, and can change the sound significantly, especially in the top end clarity, extension and transparency. You can also roll in some higher quality opamps (remember to check voltages) and exchange the very last 'lytics in the path with film caps (like Auricaps). At this point in the path, you may also exchange the stock resistors for higher grade ones like Riken carbon films.

Alternatively you can check the output voltage in the analog stage before the opamps...if they are high enough you may be able to bypass the opamp itself and send the signal through some boutique film caps straight to the RCA output instead.

 

[rickcr42]

where have I heard this before ?

Hmmmmm..........

post #7 maybe ?

 

[Teerawit]

Quote:

Originally Posted by rickcr42 where have I heard this before ? Hmmmmm.......... post #7 maybe ?

oh yeah...woops

 

[mrdon]

Quote:

Originally Posted by Teerawit oh yeah...woops

There is name for this technique, correct? It's called the Swenson Mod.

 

[rickcr42]

FYI

the technique has been around as long as the Delta-sigma DAC which already includes an output stage so allows use without another active stage

 

[nikongod]

Quote:

Originally Posted by Xakepa What do you mean by "tiny film cap"? Polyprop or polyester caps are not tiny, and even the largest ones hardy go above 2-3uF. So to have the same capacitance/cut-off freq I'll need 3-4 of those large fellas.

manufacturers OFTEN use a electrolytic between teh dac and onboard amp simply to save money. they typpically select the cheapest cap or they simply use a cap that they have to use elsewhere too (often following the "cheapest by both part quality, and buying larger quantities" school of thought)

in the case of the cap between a dac, and an opamp (or similar output stage) the input impedance of the opamp is in teh meg-ohms. you dont need but barely 0.1uf to get a very low cutoff frequency in this case... if you need more, and are limited to space like when moding a prtable player, then compromises need to be made. chances are very good that a 0.1uf mildly cheap film cap will sound wayyy better than any electrolytic you replace with it in this application. in the case of a home-based cd player there is almost always room for larger case-size caps, go wild.

 

[Xakepa]

Quote:

Originally Posted by nikongod manufacturers OFTEN use a electrolytic between teh dac and onboard amp simply to save money. they typpically select the cheapest cap or they simply use a cap that they have to use elsewhere too (often following the "cheapest by both part quality, and buying larger quantities" school of thought) in the case of the cap between a dac, and an opamp (or similar output stage) the input impedance of the opamp is in teh meg-ohms. you dont need but barely 0.1uf to get a very low cutoff frequency in this case... if you need more, and are limited to space like when moding a prtable player, then compromises need to be made. chances are very good that a 0.1uf mildly cheap film cap will sound wayyy better than any electrolytic you replace with it in this application. in the case of a home-based cd player there is almost always room for larger case-size caps, go wild.

That's true, but it doesn't (seem to) work for me. I don't know what I have after the DAC on my SC, I only know that there are 10uF coupling electrolytics. Supposedly there's nothing else, they feed the signal into the 10K Panasonic pot of my PIMETA, so the current from the decoupling caps "sees" 10K to the ground and following C>1/2*Pi*R I need 8-10uF to avoid roll-off...

 

[rickcr42]

Maybe I missed something here but if that is the case why not just use a 10uF film or PIO cap in place of the electolytic ?

 

[Garbz]

Quote:

Originally Posted by rickcr42 FYI the technique has been around as long as the Delta-sigma DAC which already includes an output stage so allows use without another active stage

In which case post an answer in my thread about a passive I/V stage for my dac

This is exactly the type of thing i'm looking for.

 

[00940]

Quote:

Originally Posted by Garbz In which case post an answer in my thread about a passive I/V stage for my dac This is exactly the type of thing i'm looking for.

Rick is speaking of DAC's with integrated I/V and voltage out. Your DAC is current out, you need a more elaborated system.

For your application, look here : http://www.diyaudio.com/forums/showt...&threadid=8434

 

[rickcr42]

Correct.

There are a couple of hybrids floating around but most Sigma-Delta DACs are fully "in the box" complete devices with not just the anti-aliasing filters but a cmos opamp buffer section following the filter section,and that is part of the problem as well as the reason you can AC couple directly to the output jacks.

Why this is problematic is no amount of wishing will allow you to bypass this section so this CMOS buffer is in the signal path 100% of the time no matter what you follow the DAC chip with and being there effects the sonics all the time.Anyone experiment with a CMOS OpAmp ?
Even the best of them are lacking in the sonics department so it comes down to making the best of a forced on us bad situation and that means taking advantage of the only "plus" and coup[ling through a cap to the output jacks without further degrading the sonics by adding in more stages.


Quote:

In which case post an answer in my thread about a passive I/V stage for my dac

you should know where I am at on that one by now.Passive resistor IV

Not the livliest dynamics but still the best method my ears know when the final listening comes into play.The trick is to find the sweet spot where you do not stress the DAC chip IV output (yes it can clip

) then make up the rest of the gain with either a transformer,a gain stage or a combination of the two (me

)

BTW-some DAC chips have a DC offset,some not.Very important when chossing either a trasnformer (some HATE DC !) or trying to nail down the resistor

 

[gaplessophile]

So do film capacitors, like polypropylene, always sound better than electrolytics? Are electrolytics only used because they're small and cheap? What are a good sort/brand of electrolytics, for situations where a film cap won't fit? Or alternatively, what are a good, small sort/brand of film cap for when size is an issue? For my application, I'd need about 4.7uF.

 

[00940]

The best electrolytics are almost as good as the basic polyprop. Common brands are Elna Cerafine and BlackGate.

For reasonably sized mkp, wima maybe.

 

[mrdon]

Quote:

Originally Posted by gaplessophile Or alternatively, what are a good, small sort/brand of film cap for when size is an issue? For my application, I'd need about 4.7uF.

I recommend the Illinois MWR Film Capacitor. IMHO, these are the "best buy" of film caps. They are available in 4.7uf in both 100V and 250V versions and can be purchased from Allied.