[deuginthesky]

Quote:

Originally Posted by minivan /img/forum/go_quote.gif does any1 know where to get replacement for the 2 regulators on the top left of this picture? they are c5171 and a1930. what brand are they? what are the spec for their output? any other regulators i can used to substitute them? thanks

Only the transistor on the top right is a regulator, a 7805 series (+5V fixed).

 

[deuginthesky]

Quote:

Originally Posted by minivan /img/forum/go_quote.gif does any1 know where to get replacement for the 2 regulators on the top left of this picture? they are c5171 and a1930. what brand are they? what are the spec for their output? any other regulators i can used to substitute them? thanks

Only the transistor on the top right is a regulator, a 7805 series (+5V fixed).

 

[deuginthesky]

Quote:

Originally Posted by minivan /img/forum/go_quote.gif does any1 know where to get replacement for the 2 regulators on the top left of this picture? they are c5171 and a1930. what brand are they? what are the spec for their output? any other regulators i can used to substitute them? thanks

Only the transistor on the top right is a regulator, a 7805 series (+5V fixed).

 

[Artemus GF]

Quote:

Originally Posted by keyid /img/forum/go_quote.gif yea I had this prob also, rolling in the lm456 or something number fixed it. Also try using optical or get better coax cable.

I'am using LME49720 (improved LM4562) now.
Now I like they more as the OPA2107 i've used before the mod.

--------------------------------------
EDIT: my caps now have this:

At the moment I'am listening with -OPA2107 and not bypassed caps-, it IMHO better than -bypassed caps and LME49720- and way better than -bypassed caps and OPA2107-.
-bypassed caps and LME49720- is IMHO more clear but less detailed than -OPA2107 and not bypassed caps-

 

[BobMcN]

There have been recent posts over at DIYAudio.com on Zhaolu 2.5A mods. Here's a link to the thread. Look at the kevinkr posts starting on page 9 and 10:

diyAudio Forums - Zhaolu DAC - a good value DAC?

The mods primarily involve improving the ground plane on the power board, as well as bypassing the analogue stage relays.

I've done many of these on my 2.5C and can say it noticeably drops the noise floor while opening up and deepening the soundstage. Well worthwhile in my opinion, but a little more challenging than just swapping out op amps.

I also installed a pulse transformer on the RCA digital input (Mouser part # PE-65612, all of $3.87). This brought the RCA input much closer to the good sound I was getting from the TOSLINK connection. There is definitely a problem with the RCA digital input on this DAC, because it should easily eclipse the TOSLINK. The pulse transformer evens the score, and avoids the stridency and digital edge (jitter) that the TOSLINK connection has. I'm not sure much more can be done to the digital board though because it is all SMD's.

Enjoy,
Bob

 

[C37]

Quote:

Originally Posted by BobMcN /img/forum/go_quote.gif The mods primarily involve improving the ground plane on the power board, as well as bypassing the analogue stage relays. I've done many of these on my 2.5C and can say it noticeably drops the noise floor while opening up and deepening the soundstage. Well worthwhile in my opinion, but a little more challenging than just swapping out op amps. I also installed a pulse transformer on the RCA digital input (Mouser part # PE-65612, all of $3.87).

Hello Bob, could you post some pics of what you've done please? There are none ( or unusable ones ) in the diyAudio forum for these mods- And as reading text with no diagram or pics is open to confusion...One of the things that attracted me over here is how well documented everything is in this thread...thanks!

 

[C37]

Which trace do you suggest to cut on connector1?
the 4th from the left?

 

[C37]

and then to do this?

 

[C37]

well, I did the mod anyway. Always a relief to fire it up and no suspect smokes or bangs...taking out the cap, i noticed the board specifies a 35V one, while i only had at hand a 25v rubycon same voltage as the one under replacement. 25v is actually under-rated: 18V after rectification becomes 25,452 V, so the writing on the board is correct, it should be 35. This 25v cap will have a shortened life...i've also cleaned the central standoff contact to chassis ground with steel wool on the chassis: while it looked just spattered with a small amount of sprayed paint, it actually took quite a bit of scrapping before the metal became shiny...

The bass from the zapfilter is really in the different league now, and handclappings in live concert sound much more natural... Now if i could do domething to stop the stupid buzzing of the transformer...

 

[Ori]

Quote:

Originally Posted by C37 /img/forum/go_quote.gif Now if i could do something to stop the stupid buzzing of the transformer...

If it's the main tranny then check if it "rocks". In that case you can tighten the metal "clamps" by applying pressure with some tool.

 

[Ori]

Heck, I just wanted to be the first to post on page 200... This journey was a lot of fun!

 

[strangedaze39]

Quote:

Originally Posted by Ori /img/forum/go_quote.gif Heck, I just wanted to be the first to post on page 200... This journey was a lot of fun!

Aw beat me to it !!!

Hey Ori since your around, I actually had a question about the Oritek V4.

I bought an Oritek, did you already swap OPA chips or if not do you think it's worth giving some a whirl on the Oritek. I know some people feel that their Zhalou improved strongly from the switch.

Also I'm new to the Oritek/Zhalou world. Does anyone have a suggestion for chips. I'm running my Oritek to a pair of Grado SR-225's Mahogany Woody'd and soon my Sennhieser HD650.

Thanks for reading

 

[C37]

Quote:

Originally Posted by Ori /img/forum/go_quote.gif If it's the main tranny then check if it "rocks". In that case you can tighten the metal "clamps" by applying pressure with some tool.

I have done it time ago ( after you told me so, thanks for the tip) , and it helps- maybe i did not express myself well enough, it not a 50/60 hz hum, it's a higher freq. pitch noise like a metallic wiiiiiiiizzz - that kicks in 1 sec or so on powering up ( after a relay switches)-

A guy on a french forum had the same problem and he was advised to blu tack the tranny instead of nuts and bolts, which is what i've done this afternoon. The wizz is still there though...

Does the main tranformer has to be earthed? I know the zap is isolated with rubber washers, but the R core of the Zhaolu?

 

[Ori]

Quote:

Originally Posted by strangedaze39 /img/forum/go_quote.gif Aw beat me to it !!! Hey Ori since your around, I actually had a question about the Oritek V4. I bought an Oritek, did you already swap OPA chips or if not do you think it's worth giving some a whirl on the Oritek.

Gotta be fast on the trigger!

There are two opamp on the OMZ. One on the power supply board and I'm sure a lot of ink was spilled over that one... The other is on the analog board and it's strictly for reducing the DC offset.
In reality, there are no "ideal circuits". This opamp has a tiny impact on the extreme low bass but it's really not worth swapping. For each unit that goes out I verify the DC offset and listen to a variety of material including low bass. This brings me to the number two rule of audio realities, which is a little vague... Something to do with diminishing returns...

 

[Ori]

Quote:

Originally Posted by C37 /img/forum/go_quote.gif Does the main tranformer has to be earthed? I know the zap is isolated with rubber washers, but the R core of the Zhaolu?

The R-core itself is not grounded and I doubt it's generating a high pitch noise. Did you clamp all the wires together? They might vibrate in close proximity to the transformers. There is also the tiny inductor under the shield. Check it carefully, there is a "live" 110 (or 220) volts in that area!
The last magnetic item is the pulse transformer on the D2 near the coaxial jack. Not likely to be the problem but who knows...