OLD THREAD DAC End by Andrea Ciuffoli

[adamus]

*with LED bias* its more natural than the dacmagic, the depth of the soundstage is greater and it makes the dacmagic sound a bit false (mids / highs too forward).

The dacmagic is brighter, so detail is more in your face, but its all there with the dacend, and i prefer the natural quality.

For me, without the led bias i found the bass to loose. IT was too warm and cuddly and a little confused in complex bass passages.

I have had a play with a css, and am unsure so far as to whether i like it or not. It tightens the bass further, but you do loose some of that lovely valve sound (for the scientists you probably read that as 'valve distortion'). Its more clinical and detailed, but not sure if i like it or not yet. The CSS also needs a lot of heatsinking, its dropping a lot of volts!

[tassosk]

Originally Posted by adamus

*with LED bias* its more natural than the dacmagic, the depth of the soundstage is greater and it makes the dacmagic sound a bit false (mids / highs too forward).

The dacmagic is brighter, so detail is more in your face, but its all there with the dacend, and i prefer the natural quality.

For me, without the led bias i found the bass to loose. IT was too warm and cuddly and a little confused in complex bass passages.

I have had a play with a css, and am unsure so far as to whether i like it or not. It tightens the bass further, but you do loose some of that lovely valve sound (for the scientists you probably read that as 'valve distortion'). Its more clinical and detailed, but not sure if i like it or not yet. The CSS also needs a lot of heatsinking, its dropping a lot of volts!

Thanks for the feedback.
Appart the output stage mods, we also have to consider the Salas suggestion regarding the bypass of the 431, if anyone has the knowledge to apply it correctly.

[adamus]

not sure, its probably not something i will be trying. on the scope there is more noise after the tl431's, so i can see why salas is suggesting it

[apelizzo]

Originally Posted by CustomHT

So where to now??

Are you gonna try and upgrade this dac or I/V tube stage to improve its performance?

First I'm gonna cross the two DACs. New DAC with old tube stage, and old DAC with new tube stage. This way I can identify where is the major issue.

Adamus, if you can help me with your experience: my friends told me that the new DAC comparing to other two already has less bass. If I apply your mod am I going to loose more bass?

Tell me if you need to know all the parts in the circuit. Sometime oscon are responsible of bass.

Do you use the passive filter before I/V?

[apelizzo]

Originally Posted by adamus

do the led bias mod, it makes a very good impact.

cathode bypass caps to my ears sound a little confused and muddy.

Replace the anode resistors with a CSS or gyrator (the later i have not tried). 7.5ma is a little too low on the 5687's, 12ma + is a good idea to be linear.

Good point Adamus, I feel the distortion is also a little high.

[adamus]

Originally Posted by apelizzo

First I'm gonna cross the two DACs. New DAC with old tube stage, and old DAC with new tube stage. This way I can identify where is the major issue.

Adamus, if you can help me with your experience: my friends told me that the new DAC comparing to other two already has less bass. If I apply your mod am I going to loose more bass?

Tell me if you need to know all the parts in the circuit. Sometime oscon are responsible of bass.

Do you use the passive filter before I/V?

Passive filter installed (bourns 120uf)

you wont loose bass, it will be more controlled and the low mids will be better resolved, i found it 'wooly' messy if you like pre mod.

Everything is was slightly better resolved for me. i find a lto of people describe wooly bass + low mid as warmth, so you will loose a little 'warmth'.

[apelizzo]

Tube stage with 5670 or russian 6N23P designed and used in my old DAC considered having better sound. Gain to be adjusted.
Also added shunt tube regulator on +/-85V

[quanghao]

Originally Posted by apelizzo

Tube stage with 5670 or russian 6N23P I designed and used in my old DAC considered having better sound. Gain to be adjusted.
Also added shunt tube regulator on +/-85V

My old DAC? what chip do you use???

[apelizzo]

Originally Posted by quanghao

My old DAC? what chip do you use???

Exactly the same setup. It's the DAC End with transformer but instead of expensive transformers I've done a tube stage.

[Pocoyo]

Tamura ???