[spore]

This thread was created to share MF V-dac modifications, be it upgrading the supplied default stock power supply or changing of capacitors and op amp.

The V-dac by itself is pretty good out of the box. However, with a little bit of modifications, the v-dac can be greatly improved.

I wont go into details of how good the v-dac sounds after modification as what sounds good to me may not be the same for others. But one thing for sure, there is great potential in v-dac which can be unleashed.

The cost of the modifications excluding the power supply is only about 10-15% of the cost of v-dac. Components cost such as capacitors and op amp are not that expensive.

I have stopped further modifications as I am pleased with the improvements. My modification list as below is just a guide which I have tried out and I welcome everyone interested to contribute. I wont be posting much here as I will be spending more of my time listening now on

Power supply:
1. Changed default supplied stock wall wart power supply to Meanwell medical power adapter P/N: MES30A-3P1J. Fitted an 2.1mm adaptor bought separately to connect to V-dac.

V-Dac:
1. C3 and C4 replaced with same kind of capacitor
2. C25 replaced
3. C45, C22, C61, C41 replaced with same kind of capacitor
4.C58, C50, C27,C29,C36,C32,C38, C30, C18 and C37 replaced with same kind of capacitor
5. C43, C46 replaced with same kind of capacitor
6. C5, C34, C44, C21, C53 and C39 replaced with same kind of capacitor
7. C14 replaced with 47uF capacitor
8. Dual NE5532 opamp changed to LME49860 at location IC7
9. Quad MC33079 opamp changed to LME49740 at location IC5

For C14, I have tried various values at 1uf, 10uF, 47uf and 100uf. 47uf and 1uf sounds better than 10uf and 100uF. Next I tried various sizes of 1uF and 47uf and finally stick with 47uf (blue) which sounds best to me.

 

[spore]

The following modifications are by Dutchamp:

Also replaced most c`s round IC7 replaced IC7 for a OP270FZ took about 4 days to run in
Changed All with styroflex
C47-C147
C51-C151
C55-C155
C60-C160
Changed all for MKP 2,2uF (no elco for exit to the preamp)
C3-C4

 

[Dutchamps]

Quote:

Changed all for MKP 2,2uF (no elco for exit to the preamp) C3-C4

Changed it to 4,7uF MKP
dont use elko`s realy, dont

That was the most big change i had heared from all the components listed.
Now my opamps are gona do a 2nd change
I replace them with Burson dual opamp who are made of 1% components
DALE resistors etc
External powersupply is in the state of beginning to make :d

 

[josep]

Well done Spore, thanks for taking the time to open this one!

 

[Dutchamps]

Some photos

Note the big caps on the output now replaced with the 4,7uF c`s

The compenents

My teac vrds 10 SE to my modified V-Dac on KT88 pushpull amps

 

[spore]

Josep, you welcome. This thread started due to your tips on v-dac modifications. I guess that there was an interest in modding v-dac and its great to see other modders work and to exchange ideas.

Dutchamp, nice work and modding you got there. Those are huge output dc caps you have there. How has the sound changed by replacing to a bigger capacitor but having a lower capacitance? Any particular reason why you chose 2.2uF?

I may try to change dc output caps to further optimize the v-dac sound as I believe that they may have a great impact/influence on the sound being in the output path.

Do post your works on the Burson Dual Opamp and power supply. Looking forward to seeing them and how to built one!

 

[Dutchamps]

Quote:

Originally Posted by spore /img/forum/go_quote.gif Dutchamp, nice work and modding you got there. Those are huge output dc caps you have there. How has the sound changed by replacing to a bigger capacitor but having a lower capacitance? Any particular reason why you chose 2.2uF?

Well if you know a little about impedance my input from the pre-amp is high in ohms, if you connect this babe to a 1kOhm input you need around 47uF
And i compute about 3,9uF to about meg ohms so that works oke without base missings.
Course if your too low you get less base signals.
And the most important isue is i changed an bi-pol. elco to a Mkp cap.
The DA factor is much lower with mkp then with electrolite kind of caps
Elco in the factor 5-20% transient loss, Mkp however can reach in 0,0001%
So the Mkp is more capable to let all audio goto your pre-amp.


Quote:

I may try to change dc output caps to further optimize the v-dac sound as I believe that they may have a great impact/influence on the sound being in the output path.

Dont forget to change those other ones too near IC 5 the 5532DD or NE5532
You can change out the NE5532 for a OP270FZ without any other change else, of course those near by standing Caps(listed above)
A ne5532 costs 2 Euro, a OP270FZ ceramic boby costs 20 euro.
Dont be afraid to get shocked, the OP270FZ isnt played and burned in.
Let it take a full 48h to get the opamp open and clear.

Quote:

Do post your works on the Burson Dual Opamp and power supply. Looking forward to seeing them and how to built one!

Today i bought the 3 connectors for pcb board, now i wait for my Burson opamp
Plan is
A Powersupply by a transformer, a bigger one

like 2 amps at 12V=
B the burson opamp goes on a extended pcb board with the selected caps, opamp, resistors (change them to carbon ones instead of those metalfilm ones) the caps listed
All placing it into a box.
C print from the dac will be inside it too. ( making a good metal plate for chelter off HF)

Spore do you have more planning into changes?
Wish i had a schematic of a dac build with tubes the 6922 or E88CC
Behind the DSD1792 dac of the V-dac
Then im far off from those opamps at all

 

[pifski]

Hello,
I look for replacement for MC33079. Here is my choices:
1. LME49740
2. AD - OP467
3. AD OP470/1
4. TI/BB OPA2107 on BrownDog adapters

Who will sound best ?

 

[elrod-tom]

Quote:

Originally Posted by spore /img/forum/go_quote.gif Power supply: 1. Changed default supplied stock wall wart power supply to Meanwell medical power adapter P/N: MES30A-3P1J. Fitted an 2.1mm adaptor bought separately to connect to V-dac.

Anyone have any suggestions for a replacement power supply that will work for us folks stateside?

 

[mrarroyo]

Quote:

Originally Posted by elrod-tom /img/forum/go_quote.gif Anyone have any suggestions for a replacement power supply that will work for us folks stateside?

PM sent.

 

[spore]

Dutchamps, I have changed the dc output caps C3 and C4 to 100uF Bipolar Nichicon Muse capacitor. In addition, I replaced the caps at C22 and C52 to Bipolar Nichicon Muse capacitor because I have some spares left for experiment.

Impressions after changes above is that imaging improves and tonality is more 'accurate'. Bass becomes punchier and transients improves. Overall sound is very balanced with no specific emphasize to any portion such as mid range, bass etc. Music is not harsh.

I am a newbie in modding and I always trial and error by swapping capacitor. Different capacitors have different sound characteristics. Its only through hearing and then can you decide if you like it or not.

Below are my updated list of modifications and which I think improves on the original v-dac sound in all areas (imaging, bass, clarity, tonality etc). Note: Mileage will vary

Modification Lists:
C25 : Nichicon Muse 1000uF (H0112)
C5,C53,C21,C44,C34: SE 100uF (S.E.66)
C14: Nichicon Muse 47uF (H9945) [Original 10uF]
C22, C52, C3, C4: Nichicon Muse Bipolar 100UF (A0204) [C3,C4 Original 47uF]
C43, C46: ELNA 1uF (0418)
C45, C61: ELNA Starget 100uF (0622)
C18, C58, C12, C16, C20, C18, C30, C37, C36, C29, C27, C28, C32, C38: ELNA Starget 10uF (0749)
IC5:LME49740NA [MC33079 Original]
IC7: LME49860NA [NE5332 Original]

pifski, I have only tried LME49740 and i think the combination of LME49860 + LME49740 is great. However, other combination may be good also. Hope those who have tried other combination speak up and share their experiences.

Bear in mind that changing the quad op amp alone without other changes may emphasize certain portion of the music such as width, depth, mid-bass, treble etc and this make the whole sound not 'coherent' and 'balanced'. It may sound worse initially. Other changes such as capacitor upgrades etc are necessary to tweak the sound to one that you like and 'balance' it out.

For me, I think all the modifications above are important and each modification plays a part. Although I do not have a original v-dac to compare, I think the modded vdac (from memory) sounds much better than the original in all area. There are more details, better tonality, Better imaging, tight and punchy bass.

For other capacitor near IC 5, I am not sure what will be a good replacement. However, I like the modded vdac sound and think I will keep this configuration without further changes unless others has interesting ideas with good results to report back.

 

[Dutchamps]

if you use caps in the path of signal MUST be mkp caps.
Powersupply is a good elco good enough.
More en better preformance is to change those 7805 7812 regulators.
They are very unplesent hearing

Asked some prices of the burson discrete opamps, they are expensive
Evaqulent of the 5532 will be about 45 euro p/p
the replacement for the mc33079P is build up out of 2 opamps
So to change them that will be 135 Euro, on a 225 euro v-dac hmmm need to think this over.

 

[josep]

Dutchamps,

If you plan to get rid of the small original box, or want to 'get serious', first thing to do is change the PS: remember you are still using the -V analog rail created by the two DC-DC switching converters, and this is FAR worse for sound than 78xx regulators and so on. A completely redone PS with +-12 (or 15)V and +5V rails is the way to go.

Unless you want to keep it 'logical', and inside the original box. Then you are almost done, Spore too but you have to try some non-elco caps on output as Dutchamps suggest

. And as he said, unless you are using a passive or strange preamp, you can be done with not much uF so that they get inside.

Miguel, nice to see you around here

Regards
Josep (aka Azazel)

 

[mrarroyo]

Hi Josep, good to see you here too!

 

[Dutchamps]

josep
I know what you mean about the power supply.
Wish i had a schematic then it should be less difficult to get things fixed.
Making mistakes can results in compleet disaster.
But powersupply from the adaptor from the original will be replaced and all components will be in a new case.
So the original case isnt being used again
building will follow first need to get all my components first.
In and outputs allready bought so i can extend it to the new case