Super V/i converted (LL1684 )

[TioFrancotirador]

Sorry if this has already been discussed, but what are those caps for? To eliminate any slight dc imbalance on the outputs of 9018? Are the transformers intolerant of even microamps of current?

See this article:
A 24 Bit DAC, the Full Glass Audio Article

I think it must the have something with frequency response.

I tried once this stage without the cap and the sound was awful (very distorted).

DC elimination is done by transformer.

With Teramoto Finemet transformer you do not have any capacitors.

 

[kmajjo]

See this article:
A 24 Bit DAC, the Full Glass Audio Article

I think it must the have something with frequency response.

I tried once this stage without the cap and the sound was awful (very distorted).

DC elimination is done by transformer.

With Teramoto Finemet transformer you do not have any capacitors.

Hello ,
There are two schools , one from Guang Hao's solution with virtual ground and one with real ground below :

Br
Jacky

 

[TioFrancotirador]

Hello ,
There are two schools , one from Guang Hao's solution with virtual ground and one with real ground below :

Br
Jacky

Well in the solution you presented DAC works in current mode. I/V is done by transformer resistance and it requires a lot of gain afterwords, that is why there is tube stage. After tube stage you will need some high quality caps anyway or transformer again to remove DC.

Instead of this one I would rather go with some kind of tube unbalancer with gain like here:
Balanced to unbalanced

People reporting it works great.

 

[analog_sa]

Well in the solution you presented DAC works in current mode. I/V is done by transformer resistance.

No, no, no. Winding resistance has nothing at all to do with i/v: it is a factor only at dc. The i/v resistance is the transformed value of the resistor loading the secondaries. Unload the secondaries and voila, the dac works in voltage mode.

 

[TioFrancotirador]

No, no, no. Winding resistance has nothing at all to do with i/v: it works only at dc. The i/v resistance is the transformed value of the resistor loading the secondaries. Unload the secondaries and voila, the dac works in voltage mode.

So you mean removing this 200R resistor on secondaries would make sabre work in voltage mode?

 

[quanghao]

[QUOTE=kmajjo;!

better you use it!

thanks

 

[analog_sa]

So you mean removing this 200R resistor on secondaries would make sabre work in voltage mode?

Absolutely.

 

[analog_sa]

better you use it!

thanks

Don't know what this means. The shown circuit illustrates an option to convert BAL>SE and get amplification at the same time. Looks plenty fine to me.

I am genuinely curious what is the purpose of the caps in the original circuit, as they have obviously been added for some reason.

 

[TioFrancotirador]

Absolutely.

Have you done it like that? Does it work?

 

[TioFrancotirador]

Isn't it better to just use unity gain tube based unbalancer like this one e.g.:
BCF PCB and Kit

No need for expensive transformer in such case.

 

[analog_sa]

Have you done it like that? Does it work?

I have not, but i guarantee it works.

 

[TioFrancotirador]

I have not, but i guarantee it works.

To expensive to be guinea pig.

 

[analog_sa]

Sorry, assumed you already have some transformers.

 

[TioFrancotirador]

Sorry, assumed you already have some transformers.

I do have LL1684 and PCB for them, but they did not work well without the caps.
It would be great if anyone would present how to wire es9038pro with LL1684 in a way were:
- sabre works in voltage mode (no additional gain needed)
- there are no caps
- there are no tubes
- SE or balanced output
So transformer simply eliminates DC offset. Same is in Teramoto Finement transformer. Only load resistor in case of SE output.

 

[analog_sa]

By saying "without" do you mean short-circuiting the caps or not installing them?

 

[TioFrancotirador]

By saying "without" do you mean short-circuiting the caps or not installing them?

Good question. From what I remember I think I just removed caps.

 

[analog_sa]

This probably explains the strange sound then.

 

[TioFrancotirador]

This probably explains the strange sound then.

So literally you suggest elimination of this 2,2-22uf cap and 10k resistor and shorting it to ground (9,10 pinout to GND in case of LL1684), right?

 

[analog_sa]

From what i gather the caps are there in order to preserve the 1.65v bias at the 9018 outputs. Active i/v or v/v stages face the same dilemma. How important is this i frankly have no idea. Connecting a low resistance transformer to ground will obviously change this potential. Would it impede the 9018 performance? I don't know. It is certainly safe to try as many have already found out. Is the sound better or worse? Dunno.

But yes, shorting the caps and resistor will allow you to conduct a very easy experiment. At least it will negate any effect the caps may have on sound.

 

[TioFrancotirador]

From what i gather the caps are there in order to preserve the 1.65v bias at the 9018 outputs. Active i/v or v/v stages face the same dilemma. How important is this i frankly have no idea. Connecting a low resistance transformer to ground will obviously change this potential. Would it impede the 9018 performance? I don't know. It is certainly safe to try as many have already found out. Is the sound better or worse? Dunno.

But yes, shorting the caps and resistor will allow you to conduct a very easy experiment. At least it will negate any effect the caps may have on sound.

In one of my DACs I have Super V/I LL1684 connected to akm4490 since I like its sound better than es9018 in voltage mode.

So, I shorted 10uf cap and 10k in this stage and ... it works and it sounds great,great,great!!!

Akm4490 is full differential voltage mode output DAC with dc offset, which is same as sabre in voltage mode, so Super V/I LL1684 without cap and resistor should also work for es90x8 in voltage mode.

Thanks!