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V-dac modifications - Page 5

post #61 of 196
First of all i respect your tourney to avoid the output caps.
Just jumper it
BUT the Tantalum caps are the most worse caps you ever could have chosen.
Even a bad electrolite is better.
Again the rest of your improvements are very good chosen but those Tantalum caps im 1000% sure of the weak preformance.

Im waiting on my psu and when its here, ill try to build it in the new casing.

Last year i made 4 mono tube amps, one pair a 6550 and one pairs of a KT88
Now the last ones are still for sale.
Not for users from USA canada or UK (115V)
Build one year back, ones used to burn in, new price 3000€
Now for 1500€ who is interested PM me
Pictures of the amps and building are here

My audioset:
2x mono tubeamps 6550 (6SN7 driver) homemade
Homemade lineamp and riaa (phono) with ecc83
Volume relector rotating switch from Elna with 144 pieces of 1% metalfilm resistors
Teac VRDS10se cd player (only use it as a cd drive) disk Clamping there is no better one (wadia uses it too)
Seas loudspeakers homemade (those will be replaced never ever i chose bass reflex anymore)

The speakers will be saw into pieces (exclude the drivers)
But need money for new ones so thats why i have to sell those nice sounding KT88

Who wants them ?
post #62 of 196

Tantalum caps

I don't understand the problem with a tantalum cap on the output of the power supply! It's just there to keep the supply from oscillating with the (relatively) long cable to the V-Dac, and to provide a little extra VHF bypassing. Show me a reputable article that shows how a tantalum cap in the power supply can somehow impact the sound of a device, and maybe I'll reconsider my choice, but for the time being, I stand by my design.
post #63 of 196

Tantalum caps

One other thing: what do you mean' "weak performance"? I have absolutely no problem with they way this thing sounds!
post #64 of 196
i cant show you articles but know this from my own and friends experiance.
If you are happy with it thats your choice hihi
Most important you need to be happy with the cap

Did you see my pics on the new casing?
post #65 of 196
Thread Starter 
I was at my local electronics store and happened to chance upon some caps near the counter. Their lead lengths are long and the 4.7uF are not expensive.

I was thinking of 4.7uF or 10uF but based on Dutchamps results, I decided to try 4.7uF. 4.7uF is smaller than 10uF and I guess they will fit 'better' with the vdac. I bought two of these and decided to try to mount them outside of the casing. The caps can fit nicely just outside the vdac casing as the dc coupling output caps are near the edge of the vdac.

In this case I do not need to spend additional money to buy another case to fit the vdac. Casing are more expensive and and I am trying to keep modification cost as low as possible.

Replacing the electrolytic capacitors to Polypropylene has a marked improvement to the sound. For my system, the music is more 3d, improved presence with better sound depth and width. Instruments and vocals are more 'natural-like', smooth and imaging is excellent. There is no drop in the bass. The bass is strong, well defined and detailed. As mentioned by Dutchamps, changing the dc output caps to Polypropylene has a marked improvement to the sound.

My music taste is more towards instruments and vocals. If you like heavy rock or heavy bass music, electrolytic caps may work much better for you.

In addition, I also changed some of the rectifier diodes to fast recovery ones. I am not sure how much improvements to the sound these make as I changed them together with the dc ouput caps.

I will like to try Burr Brown 627BP's but they are too expensive for me and there are mixed reviews on it. Imagine if buying 627BP's and finding that it is not right for me. Instead, I am spending that money to upgrade my speaker crossover caps instead.
post #66 of 196

Question for spore

Spore: just out of curiosity, how do things work with no output caps (just jumper them)? I see you are using the 49860 which should give you a minimal dc offset: depending on what you have connected to the V-DAC, you should be able to get away with no caps (unless you have a passive volume pot like me, whatever you are feeding already has some kind of DC blocking cap on the input, unless you've cut those out already). I admit that the 627BP's are probably overkill, but I've had good luck with them before, and I had them in stock.
Also, to everyone else that's still following this thread, I found this on EBay that looks very interesting for a roll your own DAC:
Hi-End USB DAC PCM2707 + PCM1798 out 12AT7 tube buffer - eBay (item 300302822268 end time Aug-20-09 20:13:02 PDT)
There are various versions of it and there's a nice power transformer for it available.
post #67 of 196
Thread Starter 
Sluggoaudio:I did not jumper the outout caps. i remembered measurring the dc offset after I switched to 49860. There was no difference in the dc offset levels from the original and they are pretty high.

With advice from kind forummers Joseph and Dutchamps, I did not try to jumper the output caps as I am afraid that it may damage the speakers. I am running the vdac output to my pre amp Bryston BP25 to my power amp Proceed AMP2 and to my speakers B&W DM602S1.

I am not sure if there is any dc blocking cap on the input of the pre-amp or power amp but I am not willing to take the risk and frying my speakers in the process. I do envy you having managed to reduce the dc offset level to such low levels.

I had spent too much in relative to the cost of the vdac while trial and error during modification and thus heistant to spend more. I am very happy with the sound of the vdac and how it gels together with my system now and do not want to risk changing it.

Now it's time for me to sit back and enjoy the music. I hope our experience will help to cut short others journey.
post #68 of 196
I read somewhere that the Pico is much better than the V-DAC for around the same price.. is this true? Or are they similar on performance?
post #69 of 196
I am planning on going through the mod route with my V-DAC. before buying the soldering station (yes, I am a newbie in modding) I would like ask couple of questions:

1) Have anyone of you found The Suggested Caps and OPAs(tm) for this box?
- ie. what would be the easy route not having to test every single chip there is on the market

2) before building PSU of my own, is it more reasonable to buy external regulated PSU?
- Is it even possible for a newbie to build PSU for this? I read some comments about V- rails and stuff which I have no clue about

3) is there a possibility to add coax inputs and implement a selector between them?
- like coax1, coax2, coax3, opt, usb
- I really hate the idea of V-DAC deciding which input it should use

I am also planning on mounting this in a new case since the V-DAC input/output placement is as stupid as it gets IMO
post #70 of 196
I know this is an enthusiast electronics thread, but I'd be incapable of making a replacement power supply for my V-DAC. Can someone suggest a commercial replacement power supply available in Australia? What improvements in sound have people found with a different power supply?
post #71 of 196
Thread Starter 
jlaakso, You can get the caps and opamps from RS components online or eeven ebay online. I bought some of the caps from ebay with opamps from RS components and some from my local electronics shop.

Different people have different taste and unfortunately you will still have to try out to see what you like.

For building of PSU and adding different inputs, I do not have experiences with it and cannot comment.

Goopie, In the other MF thread, someone did mention that he bought a power supply from one of the shops in Australia. You may want to search the thread.
post #72 of 196
for Goopie

(Page 4 this topic)
Sluggoaudio made this one and the company who sell them to export to australia maybe.

The have dealers in Austrialia
Velleman nv
post #73 of 196
You guys are freakin hilarious. Why don't you listen to some music and quit tinkering with this thing. It sounds great. The more time you tinker, the less time you have to actually LISTEN to MUSIC.

It's kind of like a violinist who just sits around and tinkers around with the violin instead of actually playing it. One day he's trying different strings. The next he's modifying his chin rest or just lookin at it like an idiot. Before he knows it, he's lost his enjoyment for playing the instrument. Worse yet, he's forgotten how to play the damn thing! LOL!

If you don't enjoy the thing, why on earth did you buy it. You should have bought a dac that you're satisfied with day one. Put down the soldering guns, caps, transistors, whatever and pick up a cd...put it in the cd player....listen and enjoy music.
post #74 of 196
I had to post again to make it 667. The 666 was freakin me out. Much better.
post #75 of 196
This topic goes about the modifing of the V dac not about comments about what we should not do to the device.
Have you ever modified one? You have only heared the original one?
This is a topic about changes for the V-Dac what do you espect?
So you only post here to get your 667th message?

The only highend audio i can read in your lines is the V-Dac so how can you judge the sound quality of the v-dac?
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