[philodox]

Quote:

Originally Posted by cotdt /img/forum/go_quote.gif balanced have 4 times the output of single-ended, so with most headphones you no longer need an amp. an amp would only degrade the sound quality if that is the case.

Are you sure the balanced outputs from the zapfilter are giving you enough voltage swing? I've heard the balanced outputs of other DAC's [Lavry DA10 and DAC1], and while it is passible... it will never replace having a nice balanced amp.

 

[philodox]

Quote:

Originally Posted by snowball_rx-7 /img/forum/go_quote.gif i have been looking for a 4 channel pot for my balanced rig, were did you find one for 20? im not up for paying the 350 DACT wants.

That would be a 4 channel stepped attenuator and not a pot. If you want a cheaper and most likely better stepper, I would contact Mikhail of Singlepower audio as he is producing steppers under the SP name and I believe he still owns Goldpoint.

 

[Epicurean]

Quote:

Originally Posted by philodox /img/forum/go_quote.gif Are you sure the balanced outputs from the zapfilter are giving you enough voltage swing? I've heard the balanced outputs of other DAC's [Lavry DA10 and DAC1], and while it is passible... it will never replace having a nice balanced amp.

At least with the CS board the Zapfilter output voltage is more than enough for HD650s(I once tried only -6dB with a very quiet song and that was louder than loud!), which means it will also be enough for most other headphones except maybe K340s and of course K1000s. However, the Zapfilter does not drive headphones that well by its own IMHO and a buffer makes a very audible difference.

 

[cotdt]

interesting, i never knew that mikhail owned goldpoint. if i were to get a stepped attenuator, goldpoint is the one to get.

as long as the headphones are over 75ohms, and don't require too much power, the zapfilter can drive them well. with my 60ohm K701s (which satisfies neither category), the zapfilter still sounds very good but I notice a little dynamics compression. Epicurian's buffer should solve that.

 

[philodox]

Quote:

Originally Posted by cotdt /img/forum/go_quote.gif interesting, i never knew that mikhail owned goldpoint. if i were to get a stepped attenuator, goldpoint is the one to get.

The goldpoint steppers are nice, but the singlepower branded ones are even nicer... works of art.

 

[daggerlee]

Quote:

Originally Posted by SonicDawg /img/forum/go_quote.gif GREAT!! I just wired my K340s directly to the zapfilter output via BAL, boy, not a whit of hum1!!!! and it sounds VERY GOOD!!! The default volume is definitely very loud, and I have not even time yet to compare to SE output via my Darkvoice. Overall, does this mean that the problem IS in the resistors then?

Are your RCA jacks isolated from the chassis??

 

[SonicDawg]

Quote:

Originally Posted by daggerlee /img/forum/go_quote.gif Are your RCA jacks isolated from the chassis??

Good idea... The RCA jacks are actually directly screwed onto the case without any layer of isolation

Might try that out soon...

 

[schuang]

Just got my Zhaolu 2.5A and has been playing with it for few days now. I think the manufacture is populating the wrong value of 6 WIMA caps (4700pf around OPA and 2200pf form inputs to ground) on mine and therefore the LPF frequency is rolling off around -3dB @20KHz (no problem for low freq, though). I have traced out the LPF circuitry and run simulation for it. The correct value should be 47pf around OPA and 470pf between inputs to ground, just as it has indicated on the PCB. With right caps value, the frequency response are pretty good: -3dB @1Hz & 79KHz. I have not tried the mod yet but the simulation shows me on the right direction. No wonder it sounds dull.

Sean

 

[ast]

got my LM4562 "free" samples from National Semiconductors yesterday and swapped out the 2604s from Headphone output stage. I am shocked by how bad they sounds! --- the sizzling treble is unbearable, I can no longer use my Shure E500 at all, only HD650 seems and deal with the terrible highs. The bass is, although a little "controlled", but much lighter than 2604.

I am gonna switch back to the factory 2604 tomorrow.


$10 down the drain

 

[Epicurean]

Quote:

Originally Posted by ast /img/forum/go_quote.gif got my LM4562 "free" samples from National Semiconductors yesterday and swapped out the 2604s from Headphone output stage. I am shocked by how bad they sounds! --- the sizzling treble is unbearable, I can no longer use my Shure E500 at all, only HD650 seems and deal with the terrible highs. The bass is, although a little "controlled", but much lighter than 2604. I am gonna switch back to the factory 2604 tomorrow. $10 down the drain

Hold on just a second! Why are you putting them in the headphone section? They should work great in the dac analog section and actually makes the highs a lot smoother compared to the opa2604. I'm sure others can confirm this. The headphone module was probably designed specifically for the opa2604 which is a fet input. The LM4562 is a bipolar input opamp and is faster which means it could be oscillating. In any case the sound you describe is the exact opposite of what it should sound like.

 

[looser101]

Quote:

Originally Posted by ast /img/forum/go_quote.gif got my LM4562 "free" samples from National Semiconductors yesterday and swapped out the 2604s from Headphone output stage. I am shocked by how bad they sounds! --- the sizzling treble is unbearable, I can no longer use my Shure E500 at all, only HD650 seems and deal with the terrible highs. The bass is, although a little "controlled", but much lighter than 2604. I am gonna switch back to the factory 2604 tomorrow. $10 down the drain

Give them some time to burn-in.

 

[El Condor]

So a quick question for somebody who's not completely familiar with this stuff (me, plus I don't have the Zhaolu specs). I understand the difference between the Phone in/Phone out and line out but is it possible to plug say 4 Ohm speakers right in the line out? From what I understand, I simply wouldn't be able to use discrete amp functionalities (increasing/decreasing volume). Is this correct? Could I actually plug speakers there (I wouldn't want to damage my equipment by trying and frying something).

 

[daggerlee]

Quote:

Originally Posted by SonicDawg /img/forum/go_quote.gif Good idea... The RCA jacks are actually directly screwed onto the case without any layer of isolation Might try that out soon...

The Zhaolu case is grounded so the hum you get is probably from a ground loop. Isolate your jacks ASAP and the problem should disappear.

 

[SonicDawg]

Quote:

Originally Posted by daggerlee /img/forum/go_quote.gif The Zhaolu case is grounded so the hum you get is probably from a ground loop. Isolate your jacks ASAP and the problem should disappear.

Unfortunately the problem is still there after I removed them from the case...

We will see how the 56ohm resistors work

 

[SonicDawg]

Quote:

Originally Posted by ast /img/forum/go_quote.gif got my LM4562 "free" samples from National Semiconductors yesterday and swapped out the 2604s from Headphone output stage. I am shocked by how bad they sounds! --- the sizzling treble is unbearable, I can no longer use my Shure E500 at all, only HD650 seems and deal with the terrible highs. The bass is, although a little "controlled", but much lighter than 2604. I am gonna switch back to the factory 2604 tomorrow. $10 down the drain

Hmmm... to me the LM4562 beats the DY2000/2604 by quite a margin. The bass quality improved quite a lot in my setup, though I must admit that the highs get a bit clearer, but it shouldn't be too glaring.