I started my new Tube DAC

[Algar_emi]

I started my new hi quality DAC using this very good desing:

http://members.brabant.chello.nl/~m.heijligers/DAChtml/dactop.htm

I got all the parts and just completed the Low Voltage Power Supply.

 

[wazzup]

That looks really good!

I was looking into that DAC myself too. I wonder how it sounds, keep the info about your project comming!

Good luck! (by looking at your board I think you won`t let the outcome depent on luck )

 

[Algar_emi]

I will keep you posted

I would be great to share with someone else on this project. But don't expect to fast a result. I'm doing this part time with the familly, 3 boys, ouf...

I will start to assemble the main DAC PCB that I got from Guido Tent (Great guy). You can buy from him with confidence. I also bought two XO low jitter clock modules for my two CD Players. I didn't have the time to install them either...

Bye.

SB

 

[Algar_emi]

DAC PCB almost finished

Here the DAC Main PCB amost finished. You can see the Jensen caps stacked together. I had to use 0.01 and 0.022 uf caps in parallel to get the needed 0.033uf cap. I needed to install the two 4.7uf MKT4 (big blue caps installed up side down) in a peculiar way. They were bigger than the one used for the desing of the pcb, probably 160V instead of the 250V that I got.

I hope that the Jensen are worth the money that I spent. They are really expensive...

 

[Algar_emi]

HV Tube output amp

Here the High Voltage Tube Amplifier PCB almost completed. The power supply choke will be connected externally using the molex connector. The big orange connector will connect the input 120V and the custom HV and filament transfo. Check the big Jensen Cap, copper foil and silver leads. I'm also using Riken, all copper, resistors in the signal path. Circuit is using Svotek 6922 tube dual triode and 6X4 Rectifier Tube.

Bye.

 

[Algar_emi]

Here the Tube output completed

Here my new tube voltage gain stage for my new DIY DAC. It is using a HV 6X4 Tube rectifier and a double triode Svotek 6922. The 6922 is using DC filement voltage using schottky rectifer and LM317T regulator. The HV is filtered using a CLC filter with two 47uF cap. an a Hammond 9H, 40ma choke.

And I just forgot. I'm also using in the signal path all copper Riken resistors and the very good Jensen copper foil and silver lead.

I will listen to this beauty soon...

Comments are welcome. Any suggestion on my tube choice will also be appreciated.

Don't be too hard on me, it is my first tube circuit. Better late than never.


Since the DAC is not completed, here a few measurements to test everything:

Bandwidth (0.767V, 1Khz reference): 20Hz-300Khz in 50 Kohms

Voltage Gain (in 50Kohms)
0.5Vin = 22.5
31.6mVin (Vout=0dB) = 24.2

Distorsion (in 50Kohms, Vout 0.767V)
100Hz: 0.5%
1Khz: 1.2%
10Khz: 1.4%
20Khz: 1.5%

Are these values of distorsion typical or an other tube brand can give me better values?

 

[Algar_emi]

And the DAC PCB back view

Here you can see that most resistors are SMD and are mounted under this nice 4 layers PCB.

 

[Algar_emi]

Here where I took the measurments

Here where I took the measurments. You can see my custom HV tranfo made by Victoria Magnetics. Incredible service, good communication and good guys. Call them for any custom needs.

Thanks again...

 

[Guido Tent]

Re: Here the Tube output completed

Distorsion (in 50Kohms, Vout 0.767V)
100Hz: 0.5%
1Khz: 1.2%
10Khz: 1.4%
20Khz: 1.5%

Are these values of distorsion typical or an other tube brand can give me better values? [/B]

Hi there

neat work !

Distortion looks higher than normal, we meaured -51 dB at 1 kHz

http://members.chello.nl/~m.heijligers/DAChtml/Measurements.htm

(scroll down)

which equals about 0,3%

which tube (brand) did you use ?

How does the residue of distortion look like ? (I hope you can monitor that) Is it harmonics or maybe 50 / 100 Hz ?

Guido

 

[Guido Tent]

Re: DAC PCB almost finished

Here the DAC Main PCB amost finished. You can see the Jensen caps stacked together. I had to use 0.01 and 0.022 uf caps in parallel to get the needed 0.033uf cap. I needed to install the two 4.7uf MKT4 (big blue caps installed up side down) in a peculiar way. They were bigger than the one used for the desing of the pcb, probably 160V instead of the 250V that I got.

Hi all

I now have limitted stock on the original 4.7 uF caps intended for the PLL loop filter. These will fit the PCB, I admit, these are quite hard to get.

 

[Algar_emi]

Distorsion

Hi Guido. I change tube and now I got the same value as you, about 0.3%. No I cannot differenciate the harmonics. I'm using a HP 334 Distorsion analyser. Yes, I agree, some line freq. harmonics may well be present and contribute to the total harmonic content.

My tube is a Svotek 6922. Any better tube for the job?

 

[Algar_emi]

Prototype almost ready

Here a picture of the complete prototype almost ready to listen to. I'm missing a 74HC393 IC.

 

[Algar_emi]

The completed DAC is working

I did it. I connected everything and it works immediatly. Thanks Guido and all your team.

My setup:
Amp: My DIY Aleph30
Preamp: Simaudio i-5, preamp section only
Speaker: Axiom 3Ti mini monitors
CD: Copland 277
I connected the DAC to cd input and the normal audio output of the Copland to A1 on the preamp. So I was able to switch rapidly between both to compare

The first listening impressions:
First of all, the DAC sound as good as the audio output of my Copland. Then after listening to the DAC I realized that the DAC sounds more relaxed, the highs were smoother, the bass naybe more firm. In general the DAC sounds more easy than the Copland. On the original Copland sound, the high were slightly aggresives compare to the DAC.

I like the way the DAC sound verymuch and it is a first impression. The DAC big Jensen All copper caps are not yet broke in.

I let everything running for break in using the Stereophile Test CD1 burning track 20. I will comment again in a few days to see if the sound improved.

Sound very promessing

 

[Algar_emi]

More listening

Incredible. I just bought the 30th anniversary version of Pink Floyd Dark Side of the Moon, I know, I know but I'm forty so...

It is the first time that I realize that the heart beat at the beginning is really from a drum. I hear it clearly. Stereo image and micro details are incredibles. The sound is so soft. No more CD agressive sound.

I have to go back to it. Bye...

SB

 

[fdegrove]

CONGRATS.

Hi,

My tube is a Svotek 6922. Any better tube for the job?

How deep are your pockets?

1/ E288CC/8223?
2/ E188CC/7308
3/ Cca...almost unobtainable
4/ E88CC/6922 European top brand
5/ Handpicked ECC88s: TFK,Philips and licensees,etc.
6/Sovteks 6922s are good though, leave them in for a few weeks to burn in and I doubt you'd want to spend megabucks on others.
7/USSR 6N1P provided the heater windings are up to it.

L'embarras du choix,

 

[Algar_emi]

Better tube

I may try the Svetlana 6N1P. I want to test my transfo tonight to check the current supply of the filament. I requested 6.3V, 0.7A min. so I should be OK.

Thanks for the suggestions.

SB

 

[Algar_emi]

I got enough current, I got the 6N1P

I got plenty of current from my tranfo. I can supply up to 1.2A so I can easily supply the 650ma needed bu the 6N1P filament. I place an other for the tubes tomorrow...

 

[Algar_emi]

So good you need a good Amp

My Dac sound so good that I started to play with the rest of the system to get the best of it. I'm using my trusty Aleph30 and just experimented with new speaker cable. SO the result at:

http://www.diyaudio.com/forums/showthread.php?s=&postid=167325#post167325

 

[Magnetmaz]

I tend to like this CAT5 cable recipie better.

http://www.venhaus1.com/diycatfivecables.html


It uses Belden teflon CAT5 cable, and has gotten many good reviews. I personally like the look of the outer jacket stripped off too. SOOO much more work involved though. Something like 5 hours to braid all the individual pairs.

-Maz

 

[fdegrove]

VENHAUS.

Hi,

I tend to like this CAT5 cable recipie better.

Cheap and cheerful and fine sounding stuff too.

Cheers,