[Realrift]

Quote:

Originally Posted by Bill Allen /img/forum/go_quote.gif Rift, Welcome to the forum. The 3.3uf Mundorf Silver Caps will sound very good by themselves, forget the bypass caps for now and focus on rewiring the analog output stage. I also have a late 2008 Valab like yours and Pat's and today I will do the "analog output" rewire mod and install Jupiter 5uf coupling caps. I will take pictures so you can see how this is done. Stay tuned.

That sounds great Bill, I will be watching keenly

I will try the Mundorf by themselves. I was worried about sticking to 4.7uF or more, but as Pat is saying here he didn't loose any bass in going to the 1uF so hopefully 3.3uF will be fine.

Thank you to all the modders here for your great work and inspiration.

Cheers,
Rift.

 

[Jogi]

Rift,

you really don't have to worry about the µF thing, 1µF is plenty in 98% of all cases.
Currently I have 0,8, and no difference to 4,7. When your preamp or poweramp has a very low impedance at the input, say under 10Kohms, there might be a slight loss in deepest frequencies, maybe is goes down to 12 HZ instead of 3

But I never met a preamp like this...
A different thing is a transformer volume control (TVC), there I would stay with 2,2 at least.
But as I have one, I can tell that even there 1µF is enough.
I think this is of some importance as those caps are pretty expensive, especially the bigger values.

Yesterday I had a nice surprise: I looked at a small adjustable power supply with 1,4 A standing around, unemployed.
So why not give it a try? Quickly soldered a cable to banana plugs fitting in the supply, desoldered one of the 3 PS caps from the Valab board, soldering the 2 cables from the power supply to the + and - holes of the desoldered cap on the board, done.
Now the transformer on the Valab board is unemployed, and as a side effect there is no noise, hum and heat from it.

So then I adjusted voltage first to 10 Volts, switched the whole thing on.

So far this is the biggest improvement of all mods I did so far.

The caps and resistor mods are working more on a tonal level, bringing more clarity , tone and colours, but this is different.
Its a bit like going from a V4 to V8 engine, much better bass, space, and an overall relaxation and authority in the whole frequency range. The high frequencies are better as well, less harsh.
I can imagine that the stock trannie is kind of too small, considering the current consumption of those 8 dac chips.
Sounds really analogue right now, and the power supply costs a whopping 40$ here in Germany.
Before spending big $$$ on caps, I would recommend this before. Its easy, quickly done, and at least in my setup results are stunning.

And maybe Valab is coming with an external supply soon, who knows...

 

[Realrift]

Quote:

Originally Posted by Jogi /img/forum/go_quote.gif Rift, you really don't have to worry about the µF thing, 1µF is plenty in 98% of all cases. Currently I have 0,8, and no difference to 4,7. When your preamp or poweramp has a very low impedance at the input, say under 10Kohms, there might be a slight loss in deepest frequencies, maybe is goes down to 12 HZ instead of 3 But I never met a preamp like this... A different thing is a transformer volume control (TVC), there I would stay with 2,2 at least. But as I have one, I can tell that even there 1µF is enough. I think this is of some importance as those caps are pretty expensive, especially the bigger values. Yesterday I had a nice surprise: I looked at a small adjustable power supply with 1,4 A standing around, unemployed. So why not give it a try? Quickly soldered a cable to banana plugs fitting in the supply, desoldered one of the 3 PS caps from the Valab board, soldering the 2 cables from the power supply to the + and - holes of the desoldered cap on the board, done. Now the transformer on the Valab board is unemployed, and as a side effect there is no noise, hum and heat from it. So then I adjusted voltage first to 10 Volts, switched the whole thing on. So far this is the biggest improvement of all mods I did so far. The caps and resistor mods are working more on a tonal level, bringing more clarity , tone and colours, but this is different. Its a bit like going from a V4 to V8 engine, much better bass, space, and an overall relaxation and authority in the whole frequency range. The high frequencies are better as well, less harsh. I can imagine that the stock trannie is kind of too small, considering the current consumption of those 8 dac chips. Sounds really analogue right now, and the power supply costs a whopping 40$ here in Germany. Before spending big $$$ on caps, I would recommend this before. Its easy, quickly done, and at least in my setup results are stunning. And maybe Valab is coming with an external supply soon, who knows...

Hi Guys,

I have ditched the 1.5uf and smaller 0.1 and 0.01uf bypassing caps for now and just running the 3.3uF.

Jogi,

That is very interesting with the power supply. I have an old power supply that was being used with an ART DI/O dac. It is a variable 9-24V and 3amp one. I would like to try using this with the dac if possible. It also has a switch for AC or DC mode. (I am guessing DC mode for the dac?)

Any chance you could post some pics of your mod

Cheers,
Rift.

 

[Bill Allen]

I played around with my late 2008 Valab Dac today and had some pretty interesting results myself. Without a doubt this board demands getting the A/C power supply off the board. (I'm sure this will also be a big benefit for the 2009 board too as Jogi descibes).

There are several issues with the layout of the 2008 board and placement of the I/V resistors. No matter where I tried grounding the RCA jacks I got a low level hum. Later I am going to try and move the I/V resistors where they belong at the Lt/Rt outputs of the Dac chips like on the 2009 board. Stay tuned.

Even with the small ground hum, adding the 5uf Jupiter Caps sounded fantastic as always. Big bold musical sound stage. I tried some 1.0uf Jupiter Cap and without a doubt this is lighter hitting brighter lit sound stage. Also nice but not my cup of tea.

Understand that it may appear that Jogi and my finding are at odds with each other but really they are not. Its a matter of semantics. Just remember once you go modding your Dac everything matters. There are no blanket statements that ever hold true. You have to try it for yourself.

 

[gfontes]

I will try the Mundorf by themselves. I was worried about sticking to 4.7uF or more, but as Pat is saying here he didn't loose any bass in going to the 1uF so hopefully 3.3uF will be fine.


I have been using 3.3uf V-Caps bypassed by .22uf Sonicap Platinum w/out any loss of bass. They are still breaking in but they sound fantastic! I also have some Blackgate FK's on order for the power supply and regulator cap (not gonna touch the chipset caps, my soldering skills are not up to the task) and hope to get them in during the coming week. I think I'm gonna order some of the Texas Components I/V resistors too and be done w/it.

I have to say that this is the best digital sound I've had in my system. My DIY history has mainly been making speakers cables and interconnects, so this is pretty new to me. This thread is fantastic, thanks to all for the great info and insight.

 

[dubai2000]

Did the same thing like Jogi - well he put me up to it

- and like him I am utterly thrilled with this mod. Perhaps he should have mentioned that our external PS are modded as well: better electrolyte caps (in my case a combination of Slitfoil and Elna Silmic) and Schottky diodes - which are beneficial in the DAC anyway. I admit I already found this little (modded) Valab quite outstanding before, but this puts it clearly into yet another (read: higher) league.

To connect the external PS was simple: I had already removed the three electrolytes between tranny and chassis (LED side) and connected one Slitfoil in their place (remember the three are parallel). So all I need was connecting the negative wire to the neg. output of the PS and the positive to the positive (easy to find - just look at the polarity of the installed electrolytes).

BTW: Of coure you don't need 'usual' connection to your mains anymore - all the power the DAC gets from the external PS through the place where one of the former electrolytes was.

 

[Realrift]

Hi All,

Gfontes- Glad to hear you are also running 3.3uF caps and liking it.

I just did the external PS mod too after being guided through it by Jogi. Still burning in the caps but I agree with the improvement. The sound is smoother, relaxed and more analogue-like.

Currently just have wires running out the top of the case. I would like to eventually make a DC input jack like bill has done.

I may also have a peek inside my external PS as it is a cheapie from ebay and see what can be upgraded.

Cheers,
Rift.

 

[dubai2000]

If the original transformer was one bottleneck, I discovered a second one (at least in my setup): the 0.1µF smt cap on the bottom side of the reclocking board. I admit that from the first I was tempted to swap this, but IMO parts of this digital gear are quite sensitive to soldering, so I was reluctant. But today I though what the heck - just go for it

Anyway, first I replaced the original cap with a film cap of the same value-yes, it sounded different (more open) but the highs were a bit sharp. So out came one of my favourite PIOs (3.6µF) and - YES - that not only removed a bottleneck, it als increased to naturalness of tone (especially noticeable on Coltrane's 'A Love Supreme' where is sax can get onto one's ears -but no more

): again more music and less gear

.

 

[mrdon]

Quote:

Originally Posted by PatOMalley /img/forum/go_quote.gif Just got around to making my order for two Cinemag CMOB-2S transformers. We'll see what they do. Might try them between my phono pre and line pre. They are inexpensive at $22.10 each + $8 shipping. breadboard and RCAs should get me into a <$100 prove the concept arena. 'bout time, huh?

Pat,

Any news on those Cinemags?

 

[PatOMalley]

They are slow.
I paid for them.
They should be shipping now.
They are more geared for industry oreders and are slow ... But steady w individual buyers.

Eta on arrival maybe next week.

 

[mrdon]

I am playing catch up on this thread and it appears that the group is definitely leaning towards using large film caps like the ones pictured above. There are certainly benefits to using these boutique caps irregardless of the fact that they don't fit inside the wee VALAB case. I for one have had tremendous results with nice film caps in many of my projects, so I do understand the reasons behind this mod.

However, playing the Devil's Advocate, in regards to the VALAB, please be advised that by performing this output cap mod using large film caps one is potentially "opening" the DAC up to all kinds of stray EMI and RFI from other components in your rack (leaving the lid off) and inside the VALAB itself and therefore potentially degrading the sound quality. This is the main reason why (to Bill Allen's chagrin

) that I am sticking with my BG-N's - small, inconspicuous, encased in metal case and therefore able to deflect any EMI and RFI nasties lurking inside my VALAB. Plus for $2.50 a piece they sound good enough for this DIY'r on a budget.

This is just my two cents, realizing I am in the minority and will be potentially flamed, but to quote Martin Luther, "Here I stand."

 

[PatOMalley]

I was able to fit two 1uF Obbligatos inside the chassis.
Good to go.

 

[krisno]

Can anybody help me.

I am running Jupiter 1.0 uf, were input lead is connected via 0.5mm silver wire to the INPUT side of the I/V resistor, and the output lead is connected via 0.5mm silver wire directly to RCA. Everything else is STOCK Valab 2009!

1) Is it dangerous in bypassing the I/V resistor as I am doing now? Will replacing the I/V resistor with higher quality + soldering output cap input lead on the output side of the I/V instead of the input, be a better sounding solution(and safer)??

2) Replacing the stock psu caps(3x rubicon) with blackgate, is it much difference? Also replacing the 10uf NEC dacchip cap with blackgates... just a bit difference or alot?

3) The 1.ppm USB clock which comes with the Valab can it be directly replaced with a Tent XO 12.000mhz clock instead? I presume the tent XO is a lower jitter clock even though it says 1ppm on the valab. Can I just 'lift out' the old clock and replace it with a better one??

(main problem for the USB solution on the valab might be that it runs on USB power). I really can't afford an empirical audio system now...

I really hope to get answer on these 3 questions. Remember, long questions don't demand long answers !! ...

thanks!

Kris

 

[Pars]

Quote:

Originally Posted by krisno /img/forum/go_quote.gif Can anybody help me. I am running Jupiter 1.0 uf, were input lead is connected via 0.5mm silver wire to the INPUT side of the I/V resistor, and the output lead is connected via 0.5mm silver wire directly to RCA. Everything else is STOCK Valab 2009! 1) Is it dangerous in bypassing the I/V resistor as I am doing now? Will replacing the I/V resistor with higher quality + soldering output cap input lead on the output side of the I/V instead of the input, be a better sounding solution(and safer)??

The I/V resistor should go from I-out of the DAC chip to ground. There should be no way to bypass it.
Quote:

Originally Posted by krisno /img/forum/go_quote.gif 3) The 1.ppm USB clock which comes with the Valab can it be directly replaced with a Tent XO 12.000mhz clock instead? I presume the tent XO is a lower jitter clock even though it says 1ppm on the valab. Can I just 'lift out' the old clock and replace it with a better one??

Not sure about this, though if the Tent is the same frequency, then yes, it should work. PPM is a meaningless spec when it comes to jitter. PPM refers to the long term stability and how closely to the rated frequency it performs. Jitter is the short term stability (i.e., phase noise).

 

[krisno]

Oh... so then I have not bypassed it.

But to get the best sound, from were should I extract the signal(by that I mean, where should I solderd the INPUT lead on my jupiters)? On the last of the two ferrite bead links? Or on the input side of the I/V resistor as I have done now....

Is the valab clock 'loose' on a socket, just to remove and insert the tent XO? Anyone tried??

Can anyone answer if the valab 1ppm clock is powered by USB or via its own psu?