[howlndog]

fellas,

i just wanted to say thanks to all for this great thread (and dac). i bought this dac a month or so ago and have been slowly upgrading (and learning)... hopefully a new case and a full-out output cap replacement will be next. here's some shots of my work-in-progress...

 

[meusickfrek]

Quote:

Originally Posted by Bill Allen /img/forum/go_quote.gif meusickfrek- There is no easy answer to this question; the simple answer is to simply bypass the stock cap with a .22uf of higher quality. Maybe even bypassing that with a .01 Russian Teflon like Pat did. I said it in the past and I will say it again; changing the I/V resistor and coupling caps is like adjusting bass and treble. This is not what you are actually doing but the net result sounds similar. This is very system dependent. For example I would not want to add a tube output supply to this Dac, here you would be missing the point completely. Simplicity is the path to accurate sound and that is what you want from "your source". Think of this like starting with pure clean water, there are plenty of ways to flavor the sound post the source if that is your bag. (And when I say flavor I not saying that in a derogatory way, I myself run a single stage tube preamp and SET monoblocks). The purity of your power supply, I/V resistors and coupling caps play a huge role in how "your system" will ultimately sound. You get what you pay for here; however the best caps on the planet will not help a poorly balanced system. Remember if you start modding the Valab Dac you are now the engineer. This is a "hard path" to start down, but ultimately it's a way of life that every audiophile needs experience for himself.

O.K. I'll start off simple--add a .22uf cap to stock coupling cap--and learn as I go. I heard obbligatos are good for highs so two premiums and here we go..

 

[PatOMalley]

Quote:

Originally Posted by meusickfrek /img/forum/go_quote.gif any thoughts on what would be the best combo, Obbligato ... snip ... PS I just bought a $50 soldering station and I've only soldered like twice in my life.....

Laying the bypass caps on top of the existing ones is an easy enough job. I would practice on old equipment to get the feel of soldering. but some crap components at Radio Shack, cut some off the old board, replaced with the radioashck stuff, etc


Like bill says, there is a deal of subjectivity and system dependency at play with this fooling around. I have taken a liking to cascading the bypass caps, meaning more than 2. Say, a 4.7uF, then a .1uF or .22uF, then a .01uF. Also using films for the 4.7, PIO, for the .1-.22, and teflon for the .01uF. My reasoning is that the different dielectrics perform within those ranges best. But that is only an opinion, maybe only a fantasy. But I like what it does and you can use it as a thumbnail for trying things out.

Hard to beat Jupiters at any rate and a big outboard case stuffed with them has got to be hard to beat ... in your system,, in your head, etc.

 

[krisno]

I have a question.

My system is PC-> USB -> Valab 2009 -> discrete solidstate amp -> AKG K 701. I tried also tube amps. My Valab 2009 is modded with obbligato 4.7uf instead of the russian tantalums which were there. The obbligato's one lead are solderd on the output where the tantalums were, and then the other lead is solderd directly on the RCA's. ...

1) Will it be even better to solder the 'input' leads on the obbligato's straight onto the iron-bead wires, so that I bypass that I/V resistor all together?

2) This is my main problem. Even when using todays discreete headphone amp or using a tube amp, whenever I use moderate to high volume(I don't really hear it on low volumes), the audio/sound is 'screeching'. Very bright, harsh stuff at the top end, which really kills the lush experience.

What the heck causes this? I have som ampohm paper in wax 0.22uf on order which I thought to bypass the obbligato's, but I guess that even though this might improve the topend it won't cure it. Is this jitter? Or what is it.... No matter what amp(atleast the good ones which lets everything through) has this problem. At high volume it pains your ears. I guess you call it 'shrills', or whatever.

Is this a fundamental problem of the NOS dac's? Or why does not anybody else have the problem?

K

 

[mrdon]

I have not listened to my VALAB for a week or so, as I have been fussing with my phono cartridge and trying to find a job!

Anyway, I fired it up today and I just want to reiterate how much I love this DAC!

I want to also reiterate how good the Elna Cerafine 200uf cap sounds. In comparison to what I remember the BG FK as kind of slow and tubby, the Cerafine is nice and tight, fast. I know I am committing DIY heresy by dethroning the mighty BG's and many here will strongly disagree with me, but to my ears the 220uf Cerafine sounds way better.

 

[Bill Allen]

Krisno,

First off let’s make sure your Valab Dac is fully broken-in, for me that means 24 hours a day for 30 days solid. (That's 720 hours if you want to do the math; I have found most people "seriously overestimate" the actual hours on their Dac ). I use an old CD player for this kind of duty, only adding some serious listening sessions after 400 hours.

By your choice of headphones and amplifiers I can see your tastes run high... like mine! I suspect your hi-end gear is simply revealing the weakness of your digital music files. (If you have access to a quality turntable you could easily narrow this down). However I'm afraid at this point you are simply hearing the sound of jitter in digital music. It creeps in everywhere and with you running basically a stock Valab Dac, well what can I say, you have Champagne Taste on a Beer Budget.

There are lots of things you can do to your Valab Dac to help with the jitter mitigation. All those mods and more can be found in the previous 25 pages of this forum. However I spoke with you via PM about a complete jitter solution and there I suspect you will find your final solution. Tough love but you know what you have to do.

 

[krisno]

Dear Bill.

Thanks for extensive reply. So you are saying the 'sharp' sound is actually not directly jitter which is created via the connection but rather 'jitter' and sharp edges in the soundtrack/movie in the first place...

Yes, I know what we discussed, but that solution is $1300 .... though US is going down the drain and with it the dollar, so maybe in local currency it will come down a bit.

Also, if I am running $1300 + Valab + mods... you are around $1500 + alot of cables.... Would it not be better to just get the Ayre 9P USB dac which has this asyncronus transfer and no jitter? .......


Let me tell you about champagne. I just went to a friends house and listened to:
Merdiain 8500DSP speakers (full digital speakers with seperate integrated amplifiers on each element. The speaker has 7 elements) + centerspeaker in same series + Meridian 7200 rear speakers..... It is the most amazing digital system I have ever heard in my life. The front 8500 speakers though are $60 000 alone or something...

But you really recommend to get the jitter lowerd, will that package fix this problem?

K

P.S. You did not answer, can I safly bypass that I/V resistor alltogether by soldering obbligato input lead onto the ferrite bead's ... ?? Is that safe and improve quality??

 

[PatOMalley]

-- Budget improvement on cheapo power cable:

I read some posts on this and thought to give it a try. You add a 1" copper pipe coupler found in the plumbing section of your local hardware store. You add this to the IEC and it will shield against ambient noise.

The power cable I used is shielded but not at the connector, which is the trick here, and I added a ferrite to seal the deal.

Well, it made no difference when I tried it on the coax input or the outputs but on the power cable maybe a better rendition of low level detail. Lowers a small bit of grunge. It's not a big thing but I don't want to take it off now either.

I noticed the change mostly on vocals. Something about the voice stepped out a bit more.

 

[r8833]

Quote:

Originally Posted by krisno /img/forum/go_quote.gif P.S. You did not answer, can I safly bypass that I/V resistor alltogether by soldering obbligato input lead onto the ferrite bead's ... ?? Is that safe and improve quality??

You cannot bypass I/V resistor. If you follow the traces from the ferrite beads they lead to I/V resistor

rich

 

[krisno]

R8833 .. my friend... Wouldn't it be bypassed then by running the input through the obbligato's BEFORE it goes through the I/V resistor? Or is the I/V running ni parallel operation? If it is I don't see how changing it will make much difference anyways..

Rich, is ampohm + obbligato still your favorite ? May I ask what your source is?

Do you have the 'edge'/'sharpness' problem as I have described above?

K

 

[r8833]

ok why don't you try it and let us know what happens

I personally wouldn't bypass the I/V resistors. the ampohm can be sourced from the tubestore.com

 

[awkwardbydesign]

A thought. I sent back some AN tantalum resistors, as Bill pointed out they are "slightly" magnetic, and replaced them with 1W Shinkohs. The ferrite beads are also magnetic, but I will be bypassing them anyway.
Has anyone noticed, and does it matter, that all the PCB and socket mounting screws are also magnetic? I have stainless and nylon screws, so I am replacing them all.
Any opinions on this?

 

[krisno]

r8833 .

you suprise me... You have bypassed the IV resistor yourself ! Remember the pictures you showed me from your dac. You had solderd the obbligato input lead directly onto the ferrite beads. That as far as I understood = bypassing the IV resistor.

K

 

[PatOMalley]

Here is a youtube showing the how/why of implementing the copper coupler:
YouTube - Marantz Reference Legendary system

 

[r8833]

Quote:

Originally Posted by krisno /img/forum/go_quote.gif r8833 . you suprise me... You have bypassed the IV resistor yourself ! Remember the pictures you showed me from your dac. You had solderd the obbligato input lead directly onto the ferrite beads. That as far as I understood = bypassing the IV resistor. K

please take dac apart and follow the traces on i/v and ferrite beads. you will then understand what I did. The beads come after I/V resistor and the resistors are there for a reason. if you like to experiment without i/v resistors please feel free to do so... just make sure you don't have any expensive speakers or head phones hooked up

Quote:

Originally Posted by Bill Allen /img/forum/go_quote.gif Gentlemen, Lets put the coffee cup down then go back and re-read this entire thread........its only 11 pages log ..... "so far". The answers to almost every recent question has previously been posted. Come on guys, lets do "a little" research before asking anymore simple questions. The last thing we all need, is another 89 page Valab Dac thread full of fluff! (No response is required just a friendly reminder)