[ROBSCIX]

Quote:

Originally Posted by stoutblock /img/forum/go_quote.gif bump, any input on the THS4032?

They are quite good actually. One of those opamps meant for others task that audio guys have adopted. These need to be put on adapters to be used on these cards.
Funny, I just built two with power caps to use in another circuit and they sound great.

 

[sokolov91]

Quote:

Originally Posted by germanium /img/forum/go_quote.gif What other audio equipment is your computer connected to. In my case I had an ungrounded preamp between the grounded speakers & the grounded computer thus creating a gound loop. When I removed the ground from the speakers the ground loop was broken & the hum along with any noise which admitedly in my case was already extremely low went away completely. It was already so lowthough that I had to turn my preamp which is very high gain up to 3/4 volume to hear it. It was probably more than 18db gain at that point. The noise now can not even be heard at full gain now. Not even any noise from the video card at all which I was hearing very subtly before.

RCA out to a LD mk V. That is it. There was no noise downstairs on my Mccormack ALD-1 pre amp that I was aware of, which is high gain.

the noise with the LD MV5 is present, even when the volume knob on the amp is turned all the way down... And when there is not music playing too and fluctuates with the load of the graphics card.

No noise when used with the headphone jack.

 

[ROBSCIX]

Quote:

Originally Posted by Shizdan /img/forum/go_quote.gif Why are people who use the headphone out saying that the buffer Op amp changes the sound? I was under the impression that the Buffer Op Amp only changed the RCA's? Or are they using an external amp connected to the Essence STX through RCA?

Just must be a bit of confusion.
This type of layout is common for some DAC's. This DAC is a current output part so it needs a converter section.

There are two dual channel opamps (JRC2114D) as it is a differential input currenct to voltage section (I/V) Followed by a single ended buffer the LM4562NA or the headphone amplifier depending on how you have the card set.

When using the line out:

(I/V)JRC2114D\
_____________Single ended buffer (LM4562NA)
(I/V)JRC2114D/

When you switch to headphone mode the circuit is re-routed to this:

(I/V)JRC2114D\
_____________Headphone Amplifier chip (TPA6120A2)
(I/V)JRC2114D/

Hope that helps.

 

[Shizdan]

Thank explains alot now. Thanks for the nice diagram!

 

[ROBSCIX]

Quote:

Originally Posted by Shizdan /img/forum/go_quote.gif Thank explains alot now. Thanks for the nice diagram!

That is basically how it is laid out and operates. Like a triangle, the two I/V at the bottom both feeding into either the buffer or the headphone amp.

 

[happosai]

Someone already tried the Burson discrete OpAmps ... "worth buying?

Burson OpAmps

 

[ROBSCIX]

Yes a few people have tried the Burson unit and the Audio-GD units.

 

[stoutblock]

Quote:

Originally Posted by ROBSCIX /img/forum/go_quote.gif They are quite good actually. One of those opamps meant for others task that audio guys have adopted. These need to be put on adapters to be used on these cards. Funny, I just built two with power caps to use in another circuit and they sound great.

Thanks, yes I am aware they need an adapter. I guess they have a sound simlar to the OPA chips but possibly even better?

 

[ROBSCIX]

Quote:

Originally Posted by stoutblock /img/forum/go_quote.gif Thanks, yes I am aware they need an adapter. I guess they have a sound simlar to the OPA chips but possibley even better?

They are very fast opamps, meant for communication work IIRC. Many like them very much for audio work but they can be unstable in some circuits.

 

[germanium]

Quote:

Originally Posted by sokolov91 /img/forum/go_quote.gif RCA out to a LD mk V. That is it. There was no noise downstairs on my Mccormack ALD-1 pre amp that I was aware of, which is high gain. the noise with the LD MV5 is present, even when the volume knob on the amp is turned all the way down... And when there is not music playing too and fluctuates with the load of the graphics card. No noise when used with the headphone jack.

Looking at the Little Dot Mk5 I do suspect a gound loop as the problem. The Maccormack would not present that problem in & of itself looking at the power cord arrangement. You need a ground loop isolator.

 

[jalyst]

Quote:

Originally Posted by happosai /img/forum/go_quote.gif Someone already tried the Burson discrete OpAmps ... "worth buying? Burson OpAmps

crikey looks like a tight fit!

 

[ROBSCIX]

Yes but they also come with extension cables to move them to a better position. Some don't like that idea though.

 

[8-bit thief]

I just replaced the stock LM4562 buffer with the OPA2228, the most noticeable change is the treble has been tuned down quite a bit, the vocals also sound a tiny bit further back, the bass has increased very small amount but it's only noticeable on certain songs, all of this characteristics are welcome considering the bass is lean, vocals are upfront and the treble is emphasized on my AD900's.

On the downside I did notice a loss in clarity (which I attribute to the treble being toned down) and while the bass has increased by a tiny amount it is less defined and more flabby/uncontrolled sounding, the pros far outweigh the cons however.

In conclusion OPA2228 + AD900's = win

Can't wait to swap the other 2 sockets.

 

[ROBSCIX]

Careful, don't wash out the sound.... The 2227 like the 2228 are known to be bassy, so if you put that in the buffer it will roll off much of the high end produced by the I/V section. If you put bassy opamps in the I/V you can get a totally washed out sound siganture. Sometimes people use a similar procedure to purposly roll-of some of the high end if they have bright cans or speakers.

 

[8-bit thief]

Quote:

Originally Posted by ROBSCIX /img/forum/go_quote.gif Careful, don't wash out the sound.... The 2227 like the 2228 are known to be bassy, so if you put that in the buffer it will roll off much of the high end produced by the I/V section. If you put bassy opamps in the I/V you can get a totally washed out sound siganture. Sometimes people use a similar procedure to purposly roll-of some of the high end if they have bright cans or speakers.

Yeah I did notice a slight loss in details, I edited my post noting that, I'm planning on switching the JRCs to OPA2107, If I lose any more detail I might just put the stock LM4562 back, but from what I've read the 2107s are one of the more brighter and more detailed sounding burr browns so I think I should be OK.