I started my new Tube DAC

[Algar_emi]

P2P Technic

Thank Peter. I agree with you. Bye...

 

[Nicwix]

I started my new hi quality DAC using this very good desing: http://members.brabant.chello.nl/~m.heijligers/DAChtml/dactop.htm ...

Hi Algar

Just got mine up and running (20 months after getting the boards) .. sound pretty smooth, but it is still early days and I don't have a decent output stage.

Guido has been most helpful.

How are things going with your DAC.

Regards, Nic

 

[Algar_emi]

progress

I'm working very hard at work, days>12hrs, ouf... So my DAC is resting alone. I'm using this time to do some burning on it using music in a loop... I'm also listening to the 6N1P tube and OPA627 opamp line stages to compare sounds...

Bye.

 

[Nicwix]

Algar

I am building a high quality discrete stage (aka Gilmore headphone amp), so will see how that goes.

I would be interested in some comparative measurements on your digital board:

1. My PLL sound output has about 80mV p-p of sawtooth (at 705kHz). On this is superimposed about 40mV of audio freq. noise. Occasionally (randomly there are much slower swings - same sort of magnitude). What does your PPL sound look like???

2. On the various supply pins, I see 10 to 20mV of high freq. noise - yours???

Thanks
Nic

 

[Nicwix]

FYI, Guido kindly provided the following info by email:

Question 1. The PLL output has about 80mV p-p of sawtooth (at 705kHz). On this is superimposed about 40mV of audio freq. noise. Occasionally (randomly) there are much slower swings - same sort of magnitude. Is that normal???"

Guido: "The sawtooth stems from the phase comperator, it runs at 11.2896MHz divided by 16". The other noise is the variation of the incoming clock, hence stems from the jitter that your drive is producing."

"Did you actually listen to this signal ? It is fun, especially when
you do all kinds of things with your CDP, like switch it off, pause, switch off the display etc"

Me: "Strikes me the PPL sound is a really good way of evaluating the quality of different transports or the effect of any changes that are made (eg PSU upgrades).

Question 2. On the various supply pins, I see 10 to 20mV of high freq. noise - normal???

Guido: "This is about the lowest you can get, as many of the digital circuits switch RF currents throughout"

Me: OK, so it is working to specificationl!!!

Guido: "What is your impression on the sound ?"

Me: Good, very smooth, but I am waiting until I have built a decent output stage before I draw any conclusions (I have not built the tube output).

Thanks for your info Guido.

Cheers, Nic.

 

[Nicwix]

DAC Output Stage

Me: "I am building a high quality discrete stage, so will see how that goes.

Guido asked: "Curious for your ideas on these stages"

I am building the following:

 

[Algar_emi]

Tube Line Stage upgrade and 6N1P

According to Guido and some other users the best sound for the Tube Line stage was using the 6N1P tube instead of the 6922.

However the transfo that I ordered had a filament secondary that cannot supply enough voltage at 1A to drive correctly the LM317 regulator. The transfo can drive 1A but the voltage drop so much that the LM317 output was only 5.4V instead of 6.3V.

Then the 6N1P tube was working but not at its optimal state. I found the tube stage sound had some kind of coloration to it. I prefer my op-amp line stage.

I ordered a small Hammond transfo, a split bobin desing (low leakage, no need for a static shield) and low profile, model 164H10, 10Vct 2A.

I installed it tonight. Now I can drive the 6N1P filament at 1A, 6.26V with ease.

WOW, The sound is now just incredible and beats the op-amp line stage hand flat. No more coloration and just like Guido said, the timing of the music is just right. The music is good and alive. With the opamp it is good but the rythm is gone.

Thanks Guido for such a nice DAC.

 

[Guido Tent]

Re: Tube Line Stage upgrade and 6N1P

According to Guido and some other users the best sound for the Tube Line stage was using the 6N1P tube instead of the 6922.

However the transfo that I ordered had a filament secondary that cannot supply enough voltage at 1A to drive correctly the LM317 regulator. The transfo can drive 1A but the voltage drop so much that the LM317 output was only 5.4V instead of 6.3V.

Then the 6N1P tube was working but not at its optimal state. I found the tube stage sound had some kind of coloration to it. I prefer my op-amp line stage.

I ordered a small Hammond transfo, a split bobin desing (low leakage, no need for a static shield) and low profile, model 164H10, 10Vct 2A.

I installed it tonight. Now I can drive the 6N1P filament at 1A, 6.26V with ease.

WOW, The sound is now just incredible and beats the op-amp line stage hand flat. No more coloration and just like Guido said, the timing of the music is just right. The music is good and alive. With the opamp it is good but the rythm is gone.

Thanks Guido for such a nice DAC.

Hi Algar,

What you found is something that not everyone realises, but sound of a tube highly depends on the (correct) heater voltage

I am happy to see you are enjoying the design, we enjoyed sharing it

regards

 

[Algar_emi]

Back of the Line Stage PCB

As requested from some of the other user, a picture of the back of my Tube line stage, done point-to-point.

 

[fdegrove]

Hi,

The transfo can drive 1A but the voltage drop so much that the LM317 output was only 5.4V instead of 6.3V.

Hmmm...that's way to low as Guido points out.

You can't possibly reach optimum performance at this heater voltage.

We'll be around if you need guidance on this.

 

[pedro]

thanks for the picture

Algar,
Thanks a lot for the picture!
Are you going to show some pictures of your case design?

Pedro.

 

[agent.5]

The project looks really good. Just wondering what gauge wire do you use for the P2P?

 

[Algar_emi]

Wire I used

I used AWG 18, Teflon coated wire. It is a multistrain OFC cooper, silver tinned.

Bye...

 

[tmd1]

Congratulations on completing this project.
I was wondering if you can give an idea of the costs to build it to date? I was just looking for a ballpark so I can see how long it will be before I can afford to try it
Thanks, Neil.

 

[Algar_emi]

DAC Cost

Here my latest parts list with all the prices in US dollards.
Total cost around 1000$.

Bye...

 

[tmd1]

Thanks a lot Algar.

 

[cclough]

I'm looking to build this beautiful piece myself, and took the liberty to go over Algar's price list.

Some of the parts he had in stock, or got locally, so I went through Digi-key and found a lot of part numbers.

I've attached it to this message, and would appreciate anyone else interested to help source the parts I've not found.

The different vendors are listed and color coated - the prices aren't correct as they're still Canadian.

I'm looking for a WIMA distributor also.

Cheers,
-Chris

 

[pedro]

my tuba dac finished

Finally, I finished Guido's team "tube dac".
Thanks to Guido Tent and, specially, to algar_emi, who help me more than a lot.
The results are fantastic:
The combination of this Tube DAC with my modified Marantz 6000 (which include, among others, Guido's XO clock, fmax clock' supply and some suggestions by Rickpt) make my equipment to play in other league (first division).
Amazing on reproducing details, tones, and space.
I have compared this combination with a Cary 300 (with valves output stage) and some others players from some friends (including a Quad, a new Rottel and a modified Meridian. Only the updated Meridian is something similar about fidelity.
Higly recommended.
Again, Thanks a lot to algar_emi.
As you can see in this and some others threads, he finished his tube dac months ago. Now he's getting ready what I suppose is going to be an extraordinary case's desing for his tube dac.

 

[pedro]

another picture

here's another picture

 

[pedro]

an another more

In this take and the one before, there's a vol pot at the back of the case which will be use whether a kind of passive pre-amp or just an attenuator between the digital section and the tube output section. I haven't decided yet.