X-DAC V3 - One more time ;o)

[Sol]

So with the imminent arrival of a pair of Burson's finest discrete opamps, I am preparing myself for a soldering session on the X-DAC V3.

Before I PM mike with a list of parts to assist with the modding session, I'm left wondering what should be on the list of things to do.

I've reveiwed both the hifiblogspot website linked from Burson's own website, and SandyK's "extreme" mods in this forum, looked back at Zanash's suggestions and think the following is in order.

Definates
=======

• Solder the Burson discrete's to the last pair of the group of Opamp locations. Bypassing with an appropiate cap.
  
• Repalce powersupply caps with something akin to the Panasonic FCs ... most mods on the web suggest stacking and bypassing the capacitors. So you end up with several sets stacked three high - though in a recent post Mike suggested a single large capacitor is often a better proposition in an amp - would this hold true for the X-DAC v3? Or should I go with the stacked approach?
  
• Replace Diodes with faster equivalents
  

I've already damped (with bitumen sheeting) the cases on all my x-components with a noticeable difference .. but this has brought a slight harshness in the upper frequencies in conjunction with some percieved mid and low range clarity. I assume the opamp rolling will bring back that sweetness.

Possibles
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I may also be tempted to try

• swopping out the board mounted RCA's, , and
  
• playing with hookup wire
  
• providing sheilding for the IC's
  
• adding damping for the IC's
  

I expect the main benefits to be in swopping out the Diodes, Caps and adding the Discrete Opamps. Is there anything else missing? Parts lists and board positions always helpful.

Does anyone have a diagram for creating a diode bridge? Please remember I'm a numpty when it comes to electronics, and while I'm getting OK with a soldering iron, I stand as much chance of learning to speak Ethiopian as grasping basic Electronics!

[Deleted]

Sol
The 2 diodes in the photo of the V3 feed the digital 5V and 3.3V regulators. The circular "blob" near them is the bridge rectifier that feeds the analogue section. You would need to mount 4 fast diodes like the UF4004 (or UF4007 etc) in it's place using a piece of veroboard or perfboard to mount them. It could be done without that, but the result would look messy,and it is best to keep their leads short to avoid HF switching radiation. Perhaps Mike knows of a suitable Schottky diode bridge rectifier (or other fast diode bridge that you could solder straight in.) To get some idea of what replacing the big 2,200uF electros would achieve,(while you are waiting for the Panasonics and diodes from Mike) you could get a couple of 100nF 63V polyester capacitors from your local electronics store and solder one across each of those existing 2,200uF capacitors under the PCB.
Replacing those other 2 diodes with UF4004 etc. may help a little , but the main one is the bridge rectifier. I presume you have pensioned off the "wallwart" and are using something like Mike designed ?
SandyK (Alex)

[Deleted]

Sol
Don't forget to replace those 2 little 100pf ceramic capacitors near the RCA jacks with either polystyrene or polypropylene 100pf capacitors.
SandyK

[Sol]

sandyk said:

Sol
The 2 diodes in the photo of the V3 feed the digital 5V and 3.3V regulators. The circular "blob" near them is the bridge rectifier that feeds the analogue section. You would need to mount 4 fast diodes like the UF4004 (or UF4007 etc) in it's place using a piece of veroboard or perfboard to mount them. It could be done without that, but the result would look messy,and it is best to keep their leads short to avoid HF switching radiation.

What I'm struggling with is how to arrange the four diodes! There's a positive and a negative terminal and two neutrals on the board - my limited electronics can help me find a diagram as shown:



I assume one lays out the diode bridge (using a schottky as an example) with each sliver marked side corresponding to the point in the diagram?

Perhaps Mike knows of a suitable Schottky diode bridge rectifier (or other fast diode bridge that you could solder straight in.)

That might make life easier .... but there's nothing like a sense of imminent danger to you check carefully!

To get some idea of what replacing the big 2,200uF electros would achieve,(while you are waiting for the Panasonics and diodes from Mike) you could get a couple of 100nF 63V polyester capacitors from your local electronics store and solder one across each of those existing 2,200uF capacitors under the PCB.

So is a bypass normally around 4 - 5% of the actual value of the main cap - or is that a matter of trial and error? (I might be a factor out here)

Replacing those other 2 diodes with UF4004 etc. may help a little , but the main one is the bridge rectifier. I presume you have pensioned off the "wallwart" and are using something like Mike designed ?
SandyK (Alex)

I have an X-PSU V3 - for two reasons: I got lucky on german ebay auction (German had bought a UK spec one and was selling it on!) and got it ridiculously cheaply; I wanted to keep the look and feel the same as I have a the DAC, CAN, and X-10 in the v3 variation.

Thanks for the help.

[Deleted]

Sol
You are correct in that the "K" of the diode is marked usually with a silver (or white) band. Like in a valve, the other end that conducts when a positive potential is connected to it , is called the "Anode" The diagram you attached is the way to wire it up. The 40V 1A rated 1N5819 Schottky diode is another good and economical choice at this voltage. It also has a lower voltage drop than the UF4004 series etc. and will give a slightly higher DC output.
Either type will be O.K. for the X-DAC.Regarding the parallel capacitor, 1% of the original value is normally used, but up to 4 or 5% shouldn't make too much difference. Most electrolytic capacitors have a marked rise in impedance as you get towards 100KHZ. The idea is to compensate for this rise in impedance. Although low ESR electrolytic capacitors have a much lower impedance than conventional capacitors up to 100KHZ, they usually seem to make the treble sound "metallic", and are better suited to the digital parts of the circuit for bypassing digital artifacts.Why don't you get a couple of each of 100nF (0.1uF) 63V and 470nF
(0.47uF) 63V, and see which sounds best in your particular application ?
If you are getting your bits from Mike, why not let him send what he feels is most appropiate ?SandyK

[PinkFloyd]

So is a bypass normally around 4 - 5% of the actual value of the main cap - or is that a matter of trial and error? (I might be a factor out here)

With a 2200uF electrolytic I'd be inclined to parallel a 2.2uF, a 220nF and a 220pF onto it (if you've got the room) sometimes a combination of film caps sounds better than just one (then again this isn't always so) but if you have the room do give it a go ensuring the leads are kept as short as possible.

By the way I stock EVOX polypropylenes in 2.2uF, 220nF and 220pF

[Deleted]

Mike
Just as a matter of interest. I did an experiment with PSU filter caps about 12 months ago,
and the most natural sounding combination was a parallel lot of 2,200uF,1,000uF,470uF. 220uF, 100uF, 47uF ,22uf,10uF,1uF,100n. It may have sounded even better with more in-between values. The reason it worked so well appears to be that each individual capacitor has it's own broad resonance impedance dip The lot together must have caused an overall, lower,but smoother impedance, albeit with a small impedance ripple.
Have a look at the specs of a 470uF electro ,for instance, and you will see what I mean.
That JLH PSU add-on showed the impedance of a 470uF electro with respect to frequency (and phase)
SandyK

[Sol]

admin said:

With a 2200uF electrolytic I'd be inclined to parallel a 2.2uF, a 220nF and a 220pF onto it (if you've got the room) sometimes a combination of film caps sounds better than just one (then again this isn't always so) but if you have the room do give it a go ensuring the leads are kept as short as possible.

By the way I stock EVOX polypropylenes in 2.2uF, 220nF and 220pF

Do you have 2200uF in anything, or potentially 3 * 750 or 3* 1000 or some such? Would the panasonics work here?

Need to take stock and work up a parts list. I can see this being a bit of a bulk order? I'll catch you on IM eventually ;o)

[PinkFloyd]

sol said:

admin said:

With a 2200uF electrolytic I'd be inclined to parallel a 2.2uF, a 220nF and a 220pF onto it (if you've got the room) sometimes a combination of film caps sounds better than just one (then again this isn't always so) but if you have the room do give it a go ensuring the leads are kept as short as possible.

By the way I stock EVOX polypropylenes in 2.2uF, 220nF and 220pF

Do you have 2200uF in anything, or potentially 3 * 750 or 3* 1000 or some such? Would the panasonics work here?

Need to take stock and work up a parts list. I can see this being a bit of a bulk order? I'll catch you on IM eventually ;o)

I have everything to meet your requirements just ask and I'll deliver

[Sol]

admin said:

I have everything to meet your requirements just ask and I'll deliver

We are not worthy - we are not worthy!

loads of caps, some diodes, and a tall swedish blonde please

[PinkFloyd]

sol said:

admin said:

With a 2200uF electrolytic I'd be inclined to parallel a 2.2uF, a 220nF and a 220pF onto it (if you've got the room) sometimes a combination of film caps sounds better than just one (then again this isn't always so) but if you have the room do give it a go ensuring the leads are kept as short as possible.

By the way I stock EVOX polypropylenes in 2.2uF, 220nF and 220pF

Do you have 2200uF in anything, or potentially 3 * 750 or 3* 1000 or some such? Would the panasonics work here?

I have Panasonic FC 35V 2200uF, Panasonic FM 35V 1000uF, Panasonic FM 35V 1200uF, A few ELNA Silmic 50V 1000uF, some Panasonic FC 63V 1000uF some lovely Rubycon 220uF 100V non polars and some super long lasting Samwha VA (130C rated) 50V 1000uF...... hundreds of them in stock.

[Sol]

It's been a few days now .. the modules have settled down, and my ears have grown used to the sound. I still very much like what I'm hearing.

Simplest way to describe them ... more natural, detailed but nice warmth coming through, and musical. There's a balance to the frquencies across the range .. no one frequency stands out, nothing is imposing over the rest of the sound.

Most noticeable on the detail side of the house is that coming through at the top and bottom frequencies. Middle frequencies feel no betetr or worse on this front. The old opamps were obviously muddying the sound here, and with the new resolution I'm hearing detail that was lost even to my headphone rig. Especially so with the sweeter top end - cymbol splashes sounding rather spectacular - cymbol tings as though the drumemr were in the room. At the lower end, bass guitar sounds awesome, natural, and integrates with the music rather than being in the way of it.

Image is everything they say, perhaps not important to everyone, but I've been wondering where this 3D image people often refer to has been hiding in my system. Width has never been my issue (fnar fnar), but front to back has always proved elusive. The modules have unlocked that element finally, and I've been enjoiying an entirely new aspect to recorded sounds that until now have been missing.

So far there are no minuses .. my initial impessions of the lack speed is unfounded. It's just that I suspect the old opamps would tend to emphasise the leading edge of a sound, and so fast sudden hits would stand out. That speed is still there, but in a more balanced presentation.

One other benefit, not initially noticed was with low volume detail. In the old set up, as the volume dropped so did the detail and the size of the sound stage. Now, even on lower levels the sound stage stays wide, and detail remains constant. Obviously at the very low levels some is lost, but I find my normal listening volumes have dropped, whereas before I'd subconsciously reach for the "volume up" button to find an optimum sound. There's a much bigger spread of acceptable volume levels now.

Of course, stepping away from often useless audiophile comparison to the "foot-tap-o-nometer" - regardless of nuances, they just sound plain better to my jigging foot!

I'm looking forward to fitting a recommended bypass capacitor to the pins, and additonal x-dac v3 mods will include replacement caps and diodes. The parts order is in with Mike at the moment. Will be interesting to see how thing might improve some more. Perhpa swith betetr components I'll find some additonal gloss on the current presentation - we'll see!

[PinkFloyd]

Perhaps with better components I'll find some additonal gloss on the current presentation - we'll see!

One thing you don't want to do is over egg your pudding Sol. Sounds like you have found a nice balance to the sound and that can be tipped off balance oh so easily if you throw parts into the circuit willy nilly / holus bolus.

For sure fit better quality caps etc. but do them one by one and monitor the situation to ascertain the sound is going in the direction you want it to. It's easy to tell if swapping out one capacitor has made an improvement but not so easy when you swap out 30 in one go.

Sometimes more is less in the audio world and more often less can be more. You've reached a stage now where you're happy with the sound..... proceed slowly from now on in and evaluate after each part is installed..... many times I have gone the full monty only to find the sound has changed for the worse.... patience and actually evaluating "each" singular component's worth in the circuit is the way to go.... that's what true tweaking is all about, knowing what part sounds good where and when to stop..... it's all too easy to over egg that pudding

Sounds like you're at a good point of reference at the moment and can always go back there...... this is the secret..... small steps and document each stage of the journey.... don't go all out full frontal in one go cause you'll end up confuddled and none the wiser as to what is exactly contributing what to the sonics......

One component at a time sweet jesus....................

[PinkFloyd]

BTW, your parts order is deliberately on hold and I think I'll feed you certain parts at my leisure to make sure you do take the time to appreciate and evaluate each single component as they are fed to you...... I think you've got the wherewithall to become a seriously accomplished tweaker (one who understands / can articulate change) but best to go the one step at a time (sweet Jesus) route

[Deleted]

VERY SOUND ADVICE!
And don't forget to reverse the previous change if you aren't completely convinced that it sounds better. Listen for a couple of days, then decide. You can always retry the change again. It often helps to have another pair of trusted ears, someone who is quite familiar with the sound of your gear.
SandyK

[PinkFloyd]

mrarroyo said:

sol said:

...., and a tall swedish blonde please

What about a short Midget?



As "valid" as a tall Blond and possibly more interesting under extreme interview conditions........I'm sure I'd get a better level of conversation discussing the Sennheiser veil with the midget than I would from the blonde tart ;D

Team "we are the world we are the midgets" (feed the world etc.)