[looser101]

Quote:

Originally Posted by udo /img/forum/go_quote.gif The grey cable has LEFT + , - and ground & RIGHT + , - and ground. What type of output has the CS DAC chip? Voltage or current?

CS4398 is balanced voltage output.

-R-

 

[fran]

Hi All,

I just got a 2.5C from eddie. I got the amp upgrade - and there was a loose circuit board in the box as well. I take it he installs the upgraded amp and then the one I've got "extra" is the original normal one? It has 4 voltage regs along the back of the board, 2 BB0PA2604AP op-amp and theres number GQ643E at the top right hand corner of the board.

Fran

 

[adhoc]

Quote:

Originally Posted by fran /img/forum/go_quote.gif Hi All, I just got a 2.5C from eddie. I got the amp upgrade - and there was a loose circuit board in the box as well. I take it he installs the upgraded amp and then the one I've got "extra" is the original normal one? It has 4 voltage regs along the back of the board, 2 BB0PA2604AP op-amp and theres number GQ643E at the top right hand corner of the board. Fran

Yep, that's it.

Enjoy your ZL! It's a neat DAC IMO.

 

[Ori]

Quote:

Originally Posted by adhoc /img/forum/go_quote.gif Mine's a 2.0, CS4398. It's quite a different beast now that I've replaced the rectifiers, caps, jacks and added toroids..

How about some pics and a quick report on the "new" sound?!

 

[eVITAERC]

With the CS4398 DAC chip, is there any advantage to using a full-fangled output stage at all? Since the chip's is voltage out, wouldn't a simple buffer work well as well? The only advantage to additional circuitry I could see is a ~20kHz LP filter in the output path (even that is questionable given the recent revival of NOS DACs with no such filters). Otherwise wouldn't say a simple diamond buffer module work equally well?

 

[Ori]

Quote:

Originally Posted by eVITAERC /img/forum/go_quote.gif With the CS4398 DAC chip, is there any advantage to using a full-fangled output stage at all? Since the chip's is voltage out, wouldn't a simple buffer work well as well? The only advantage to additional circuitry I could see is a ~20kHz LP filter in the output path

RF noise is a major concern for most analog amplifiers I've heard

so the LP filter is sometimes essential.
The next issue would be dynamics. The output impedance specs can be deceiving, since they are calculated on the basis of a feedback circuit. To my ears high-levels of feedback have a negative effect on transient response and sometimes it masks high harmonics, which are responsible for a good portion of the soundstage realism. This may be very much a matter of taste, so the best thing you can do is try it both ways. I did (with an AD1852) and I felt there was some "slowdown" with the unbuffered output, even when driving minimal load. Unbuffered outputs may sound better than some output circuits, depending on what else you have the patience to try...

It's basically the old debate of passive vs. active and i doubt you'll get any concensus if you survey a large group.

 

[dj3500]

Hi everyone. I'm planning on getting a Zhaolu D2.5 from Eddie Wu with the discrete amp upgrade. Now, there are two versions - the AD1852 and CS4398 chips, the latter costing $66 more. I listen mostly to electronic stuff through Senn HD555 (planning to upgrade to HD595, HD650 or some beyers in the future). Which will create a better synergy with my musical tastes and phones, and is the upgrade worth getting for the price, especially given that the C version also replaces the opamps in stock headamp, which I won't use anyways? Thanks for feedback in advance.

And one more thing, how does bypassing the dc caps mod contribute to the sound quality?

 

[Nick63]

I have the Zhaolu D2. Can the opa637's be used for all 3 opamps on the board?

 

[Sean H]

Quote:

Originally Posted by Nick63 /img/forum/go_quote.gif I have the Zhaolu D2. Can the opa637's be used for all 3 opamps on the board? Nick

Not directly. The opamps in the Zhaolu are dual channel opamps where your 637 is a single channel opamp. What you would need to do is use two 637's mounted on a Brown Dog single to dual opamp adapter. Here's a pic:

You could solder the 637's directly or you would need to solder on DIP sockets. So if you wanted to fill up all three opamp positions then you would need six 637's, again using two on an adapter to make a dual opamp. That's a bit spendy. I tried a pair of 627's on an adpater and used it in the center opamp position and I have to tell you I did not like it. I mean it sounded ok but not the greatest. I know the 627 and 637 are excellent opamps and are among my favorites but for some reason used in this way in a Zhaolu I think they are not being optimally powered or something because it didn't sound as excellent as a I know a 627 can. Give it a shot though if you want. I like the OPA2107's in a Zhaolu better myself.

 

[Nick63]

That is great info. I think I will have to try the opa2107's then. Thanks for the explanation. The picture of the dual adapter made it clear. Would you use the OPA2107's for all three?

Quote:

Originally Posted by Sean H /img/forum/go_quote.gif Not directly. The opamps in the Zhaolu are dual channel opamps where your 637 is a single channel opamp. What you would need to do is use two 637's mounted on a Brown Dog single to dual opamp adapter. Here's a pic: You could solder the 637's directly or you would need to solder on DIP sockets. So if you wanted to fill up all three opamp positions then you would need six 637's, again using two on an adapter to make a dual opamp. That's a bit spendy. I tried a pair of 627's on an adpater and used it in the center opamp position and I have to tell you I did not like it. I mean it sounded ok but not the greatest. I know the 627 and 637 are excellent opamps and are among my favorites but for some reason used in this way in a Zhaolu I think they are not being optimally powered or something because it didn't sound as excellent as a I know a 627 can. Give it a shot though if you want. I like the OPA2107's in a Zhaolu better myself.

 

[Sean H]

Quote:

Originally Posted by Nick63 /img/forum/go_quote.gif That is great info. I think I will have to try the opa2107's then. Thanks for the explanation. The picture of the dual adapter made it clear. Would you use the OPA2107's for all three?

It just takes some experimentation. Three 2107's in a D2 sounds great. The 2107's sound very much like a 627 so they have the classic burr brown sound which leans a bit to the warmer and bassy side of things with a airy but smooth high end. I have found that mixing these with a brighter opamp yields good results too, kind of a balance thing. Kind of an experimental thing really.

 

[Nick63]

Quote:

Originally Posted by Sean H /img/forum/go_quote.gif I have found that mixing these with a brighter opamp yields good results too, kind of a balance thing. Kind of an experimental thing really.

What are 2 or 3 good brighter opamp to try mixed with with two opa2107's? I can't loose since most of these opamps are cheap.

 

[udo]

My Zapfilter is shipping today!

Could somebody please post some hires pics of the D2.5C DAC board, near the CS DAC chip and the connector to the analog board?

 

[adhoc]

Quote:

Originally Posted by Ori /img/forum/go_quote.gif How about some pics and a quick report on the "new" sound?!

Hey there Ori - just saw your post(!)

Give me a few days to reflow every solder joint on the board and then I'll supply some pics. Or if you're patient, give me a month or so to get my new case in and properly drill it.

 

[daggerlee]

Quote:

Originally Posted by udo /img/forum/go_quote.gif My Zapfilter is shipping today! Could somebody please post some hires pics of the D2.5C DAC board, near the CS DAC chip and the connector to the analog board?

Did you order from partsconnexion? If so I gotta call em and see if they have my order ready!